linux-vybrid_public/drivers/usb/host/xhci.c

/*
 * xHCI host controller driver
 *
 * Copyright (C) 2008 Intel Corp.
 *
 * Author: Sarah Sharp
 * Some code borrowed from the Linux EHCI driver.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/pci.h>
#include <linux/irq.h>
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>

#include "xhci.h"

#define DRIVER_AUTHOR "Sarah Sharp"
#define DRIVER_DESC "'eXtensible' Host Controller (xHC) Driver"

/* Some 0.95 hardware can't handle the chain bit on a Link TRB being cleared */
static int link_quirk;
module_param(link_quirk, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(link_quirk, "Don't clear the chain bit on a link TRB");

/* TODO: copied from ehci-hcd.c - can this be refactored? */
/*
 * handshake - spin reading hc until handshake completes or fails
 * @ptr: address of hc register to be read
 * @mask: bits to look at in result of read
 * @done: value of those bits when handshake succeeds
 * @usec: timeout in microseconds
 *
 * Returns negative errno, or zero on success
 *
 * Success happens when the "mask" bits have the specified value (hardware
 * handshake done).  There are two failure modes:  "usec" have passed (major
 * hardware flakeout), or the register reads as all-ones (hardware removed).
 */
static int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
		      u32 mask, u32 done, int usec)
{
	u32	result;

	do {
		result = xhci_readl(xhci, ptr);
		if (result == ~(u32)0)		/* card removed */
			return -ENODEV;
		result &= mask;
		if (result == done)
			return 0;
		udelay(1);
		usec--;
	} while (usec > 0);
	return -ETIMEDOUT;
}

/*
 * Disable interrupts and begin the xHCI halting process.
 */
void xhci_quiesce(struct xhci_hcd *xhci)
{
	u32 halted;
	u32 cmd;
	u32 mask;

	mask = ~(XHCI_IRQS);
	halted = xhci_readl(xhci, &xhci->op_regs->status) & STS_HALT;
	if (!halted)
		mask &= ~CMD_RUN;

	cmd = xhci_readl(xhci, &xhci->op_regs->command);
	cmd &= mask;
	xhci_writel(xhci, cmd, &xhci->op_regs->command);
}

/*
 * Force HC into halt state.
 *
 * Disable any IRQs and clear the run/stop bit.
 * HC will complete any current and actively pipelined transactions, and
 * should halt within 16 ms of the run/stop bit being cleared.
 * Read HC Halted bit in the status register to see when the HC is finished.
 */
int xhci_halt(struct xhci_hcd *xhci)
{
	int ret;
	xhci_dbg(xhci, "// Halt the HC\n");
	xhci_quiesce(xhci);

	ret = handshake(xhci, &xhci->op_regs->status,
			STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
	if (!ret)
		xhci->xhc_state |= XHCI_STATE_HALTED;
	return ret;
}

/*
 * Set the run bit and wait for the host to be running.
 */
static int xhci_start(struct xhci_hcd *xhci)
{
	u32 temp;
	int ret;

	temp = xhci_readl(xhci, &xhci->op_regs->command);
	temp |= (CMD_RUN);
	xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n",
			temp);
	xhci_writel(xhci, temp, &xhci->op_regs->command);

	/*
	 * Wait for the HCHalted Status bit to be 0 to indicate the host is
	 * running.
	 */
	ret = handshake(xhci, &xhci->op_regs->status,
			STS_HALT, 0, XHCI_MAX_HALT_USEC);
	if (ret == -ETIMEDOUT)
		xhci_err(xhci, "Host took too long to start, "
				"waited %u microseconds.\n",
				XHCI_MAX_HALT_USEC);
	if (!ret)
		xhci->xhc_state &= ~XHCI_STATE_HALTED;
	return ret;
}

/*
 * Reset a halted HC.
 *
 * This resets pipelines, timers, counters, state machines, etc.
 * Transactions will be terminated immediately, and operational registers
 * will be set to their defaults.
 */
int xhci_reset(struct xhci_hcd *xhci)
{
	u32 command;
	u32 state;
	int ret;

	state = xhci_readl(xhci, &xhci->op_regs->status);
	if ((state & STS_HALT) == 0) {
		xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
		return 0;
	}

	xhci_dbg(xhci, "// Reset the HC\n");
	command = xhci_readl(xhci, &xhci->op_regs->command);
	command |= CMD_RESET;
	xhci_writel(xhci, command, &xhci->op_regs->command);

	ret = handshake(xhci, &xhci->op_regs->command,
			CMD_RESET, 0, 250 * 1000);
	if (ret)
		return ret;

	xhci_dbg(xhci, "Wait for controller to be ready for doorbell rings\n");
	/*
	 * xHCI cannot write to any doorbells or operational registers other
	 * than status until the "Controller Not Ready" flag is cleared.
	 */
	return handshake(xhci, &xhci->op_regs->status, STS_CNR, 0, 250 * 1000);
}

/*
 * Free IRQs
 * free all IRQs request
 */
static void xhci_free_irq(struct xhci_hcd *xhci)
{
	int i;
	struct pci_dev *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

	/* return if using legacy interrupt */
	if (xhci_to_hcd(xhci)->irq >= 0)
		return;

	if (xhci->msix_entries) {
		for (i = 0; i < xhci->msix_count; i++)
			if (xhci->msix_entries[i].vector)
				free_irq(xhci->msix_entries[i].vector,
						xhci_to_hcd(xhci));
	} else if (pdev->irq >= 0)
		free_irq(pdev->irq, xhci_to_hcd(xhci));

	return;
}

/*
 * Set up MSI
 */
static int xhci_setup_msi(struct xhci_hcd *xhci)
{
	int ret;
	struct pci_dev  *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

	ret = pci_enable_msi(pdev);
	if (ret) {
		xhci_err(xhci, "failed to allocate MSI entry\n");
		return ret;
	}

	ret = request_irq(pdev->irq, (irq_handler_t)xhci_msi_irq,
				0, "xhci_hcd", xhci_to_hcd(xhci));
	if (ret) {
		xhci_err(xhci, "disable MSI interrupt\n");
		pci_disable_msi(pdev);
	}

	return ret;
}

/*
 * Set up MSI-X
 */
static int xhci_setup_msix(struct xhci_hcd *xhci)
{
	int i, ret = 0;
	struct usb_hcd *hcd = xhci_to_hcd(xhci);
	struct pci_dev *pdev = to_pci_dev(hcd->self.controller);

	/*
	 * calculate number of msi-x vectors supported.
	 * - HCS_MAX_INTRS: the max number of interrupts the host can handle,
	 *   with max number of interrupters based on the xhci HCSPARAMS1.
	 * - num_online_cpus: maximum msi-x vectors per CPUs core.
	 *   Add additional 1 vector to ensure always available interrupt.
	 */
	xhci->msix_count = min(num_online_cpus() + 1,
				HCS_MAX_INTRS(xhci->hcs_params1));

	xhci->msix_entries =
		kmalloc((sizeof(struct msix_entry))*xhci->msix_count,
				GFP_KERNEL);
	if (!xhci->msix_entries) {
		xhci_err(xhci, "Failed to allocate MSI-X entries\n");
		return -ENOMEM;
	}

	for (i = 0; i < xhci->msix_count; i++) {
		xhci->msix_entries[i].entry = i;
		xhci->msix_entries[i].vector = 0;
	}

	ret = pci_enable_msix(pdev, xhci->msix_entries, xhci->msix_count);
	if (ret) {
		xhci_err(xhci, "Failed to enable MSI-X\n");
		goto free_entries;
	}

	for (i = 0; i < xhci->msix_count; i++) {
		ret = request_irq(xhci->msix_entries[i].vector,
				(irq_handler_t)xhci_msi_irq,
				0, "xhci_hcd", xhci_to_hcd(xhci));
		if (ret)
			goto disable_msix;
	}

	hcd->msix_enabled = 1;
	return ret;

disable_msix:
	xhci_err(xhci, "disable MSI-X interrupt\n");
	xhci_free_irq(xhci);
	pci_disable_msix(pdev);
free_entries:
	kfree(xhci->msix_entries);
	xhci->msix_entries = NULL;
	return ret;
}

/* Free any IRQs and disable MSI-X */
static void xhci_cleanup_msix(struct xhci_hcd *xhci)
{
	struct usb_hcd *hcd = xhci_to_hcd(xhci);
	struct pci_dev *pdev = to_pci_dev(hcd->self.controller);

	xhci_free_irq(xhci);

	if (xhci->msix_entries) {
		pci_disable_msix(pdev);
		kfree(xhci->msix_entries);
		xhci->msix_entries = NULL;
	} else {
		pci_disable_msi(pdev);
	}

	hcd->msix_enabled = 0;
	return;
}

/*
 * Initialize memory for HCD and xHC (one-time init).
 *
 * Program the PAGESIZE register, initialize the device context array, create
 * device contexts (?), set up a command ring segment (or two?), create event
 * ring (one for now).
 */
int xhci_init(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	int retval = 0;

	xhci_dbg(xhci, "xhci_init\n");
	spin_lock_init(&xhci->lock);
	if (link_quirk) {
		xhci_dbg(xhci, "QUIRK: Not clearing Link TRB chain bits.\n");
		xhci->quirks |= XHCI_LINK_TRB_QUIRK;
	} else {
		xhci_dbg(xhci, "xHCI doesn't need link TRB QUIRK\n");
	}
	retval = xhci_mem_init(xhci, GFP_KERNEL);
	xhci_dbg(xhci, "Finished xhci_init\n");

	return retval;
}

/*-------------------------------------------------------------------------*/


#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
static void xhci_event_ring_work(unsigned long arg)
{
	unsigned long flags;
	int temp;
	u64 temp_64;
	struct xhci_hcd *xhci = (struct xhci_hcd *) arg;
	int i, j;

	xhci_dbg(xhci, "Poll event ring: %lu\n", jiffies);

	spin_lock_irqsave(&xhci->lock, flags);
	temp = xhci_readl(xhci, &xhci->op_regs->status);
	xhci_dbg(xhci, "op reg status = 0x%x\n", temp);
	if (temp == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING)) {
		xhci_dbg(xhci, "HW died, polling stopped.\n");
		spin_unlock_irqrestore(&xhci->lock, flags);
		return;
	}

	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
	xhci_dbg(xhci, "ir_set 0 pending = 0x%x\n", temp);
	xhci_dbg(xhci, "HC error bitmask = 0x%x\n", xhci->error_bitmask);
	xhci->error_bitmask = 0;
	xhci_dbg(xhci, "Event ring:\n");
	xhci_debug_segment(xhci, xhci->event_ring->deq_seg);
	xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
	temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
	temp_64 &= ~ERST_PTR_MASK;
	xhci_dbg(xhci, "ERST deq = 64'h%0lx\n", (long unsigned int) temp_64);
	xhci_dbg(xhci, "Command ring:\n");
	xhci_debug_segment(xhci, xhci->cmd_ring->deq_seg);
	xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
	xhci_dbg_cmd_ptrs(xhci);
	for (i = 0; i < MAX_HC_SLOTS; ++i) {
		if (!xhci->devs[i])
			continue;
		for (j = 0; j < 31; ++j) {
			xhci_dbg_ep_rings(xhci, i, j, &xhci->devs[i]->eps[j]);
		}
	}
	spin_unlock_irqrestore(&xhci->lock, flags);

	if (!xhci->zombie)
		mod_timer(&xhci->event_ring_timer, jiffies + POLL_TIMEOUT * HZ);
	else
		xhci_dbg(xhci, "Quit polling the event ring.\n");
}
#endif

static int xhci_run_finished(struct xhci_hcd *xhci)
{
	if (xhci_start(xhci)) {
		xhci_halt(xhci);
		return -ENODEV;
	}
	xhci->shared_hcd->state = HC_STATE_RUNNING;

	if (xhci->quirks & XHCI_NEC_HOST)
		xhci_ring_cmd_db(xhci);

	xhci_dbg(xhci, "Finished xhci_run for USB3 roothub\n");
	return 0;
}

/*
 * Start the HC after it was halted.
 *
 * This function is called by the USB core when the HC driver is added.
 * Its opposite is xhci_stop().
 *
 * xhci_init() must be called once before this function can be called.
 * Reset the HC, enable device slot contexts, program DCBAAP, and
 * set command ring pointer and event ring pointer.
 *
 * Setup MSI-X vectors and enable interrupts.
 */
int xhci_run(struct usb_hcd *hcd)
{
	u32 temp;
	u64 temp_64;
	u32 ret;
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	struct pci_dev  *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

	/* Start the xHCI host controller running only after the USB 2.0 roothub
	 * is setup.
	 */

	hcd->uses_new_polling = 1;
	if (!usb_hcd_is_primary_hcd(hcd))
		return xhci_run_finished(xhci);

	xhci_dbg(xhci, "xhci_run\n");
	/* unregister the legacy interrupt */
	if (hcd->irq)
		free_irq(hcd->irq, hcd);
	hcd->irq = -1;

	ret = xhci_setup_msix(xhci);
	if (ret)
		/* fall back to msi*/
		ret = xhci_setup_msi(xhci);

	if (ret) {
		/* fall back to legacy interrupt*/
		ret = request_irq(pdev->irq, &usb_hcd_irq, IRQF_SHARED,
					hcd->irq_descr, hcd);
		if (ret) {
			xhci_err(xhci, "request interrupt %d failed\n",
					pdev->irq);
			return ret;
		}
		hcd->irq = pdev->irq;
	}

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
	init_timer(&xhci->event_ring_timer);
	xhci->event_ring_timer.data = (unsigned long) xhci;
	xhci->event_ring_timer.function = xhci_event_ring_work;
	/* Poll the event ring */
	xhci->event_ring_timer.expires = jiffies + POLL_TIMEOUT * HZ;
	xhci->zombie = 0;
	xhci_dbg(xhci, "Setting event ring polling timer\n");
	add_timer(&xhci->event_ring_timer);
#endif

	xhci_dbg(xhci, "Command ring memory map follows:\n");
	xhci_debug_ring(xhci, xhci->cmd_ring);
	xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
	xhci_dbg_cmd_ptrs(xhci);

	xhci_dbg(xhci, "ERST memory map follows:\n");
	xhci_dbg_erst(xhci, &xhci->erst);
	xhci_dbg(xhci, "Event ring:\n");
	xhci_debug_ring(xhci, xhci->event_ring);
	xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
	temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
	temp_64 &= ~ERST_PTR_MASK;
	xhci_dbg(xhci, "ERST deq = 64'h%0lx\n", (long unsigned int) temp_64);

	xhci_dbg(xhci, "// Set the interrupt modulation register\n");
	temp = xhci_readl(xhci, &xhci->ir_set->irq_control);
	temp &= ~ER_IRQ_INTERVAL_MASK;
	temp |= (u32) 160;
	xhci_writel(xhci, temp, &xhci->ir_set->irq_control);

	/* Set the HCD state before we enable the irqs */
	temp = xhci_readl(xhci, &xhci->op_regs->command);
	temp |= (CMD_EIE);
	xhci_dbg(xhci, "// Enable interrupts, cmd = 0x%x.\n",
			temp);
	xhci_writel(xhci, temp, &xhci->op_regs->command);

	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
	xhci_dbg(xhci, "// Enabling event ring interrupter %p by writing 0x%x to irq_pending\n",
			xhci->ir_set, (unsigned int) ER_IRQ_ENABLE(temp));
	xhci_writel(xhci, ER_IRQ_ENABLE(temp),
			&xhci->ir_set->irq_pending);
	xhci_print_ir_set(xhci, 0);

	if (xhci->quirks & XHCI_NEC_HOST)
		xhci_queue_vendor_command(xhci, 0, 0, 0,
				TRB_TYPE(TRB_NEC_GET_FW));

	xhci_dbg(xhci, "Finished xhci_run for USB2 roothub\n");
	return 0;
}

static void xhci_only_stop_hcd(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);

	spin_lock_irq(&xhci->lock);
	xhci_halt(xhci);

	/* The shared_hcd is going to be deallocated shortly (the USB core only
	 * calls this function when allocation fails in usb_add_hcd(), or
	 * usb_remove_hcd() is called).  So we need to unset xHCI's pointer.
	 */
	xhci->shared_hcd = NULL;
	spin_unlock_irq(&xhci->lock);
}

/*
 * Stop xHCI driver.
 *
 * This function is called by the USB core when the HC driver is removed.
 * Its opposite is xhci_run().
 *
 * Disable device contexts, disable IRQs, and quiesce the HC.
 * Reset the HC, finish any completed transactions, and cleanup memory.
 */
void xhci_stop(struct usb_hcd *hcd)
{
	u32 temp;
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);

	if (!usb_hcd_is_primary_hcd(hcd)) {
		xhci_only_stop_hcd(xhci->shared_hcd);
		return;
	}

	spin_lock_irq(&xhci->lock);
	/* Make sure the xHC is halted for a USB3 roothub
	 * (xhci_stop() could be called as part of failed init).
	 */
	xhci_halt(xhci);
	xhci_reset(xhci);
	spin_unlock_irq(&xhci->lock);

	xhci_cleanup_msix(xhci);

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
	/* Tell the event ring poll function not to reschedule */
	xhci->zombie = 1;
	del_timer_sync(&xhci->event_ring_timer);
#endif

	if (xhci->quirks & XHCI_AMD_PLL_FIX)
		usb_amd_dev_put();

	xhci_dbg(xhci, "// Disabling event ring interrupts\n");
	temp = xhci_readl(xhci, &xhci->op_regs->status);
	xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
	temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
	xhci_writel(xhci, ER_IRQ_DISABLE(temp),
			&xhci->ir_set->irq_pending);
	xhci_print_ir_set(xhci, 0);

	xhci_dbg(xhci, "cleaning up memory\n");
	xhci_mem_cleanup(xhci);
	xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
		    xhci_readl(xhci, &xhci->op_regs->status));
}

/*
 * Shutdown HC (not bus-specific)
 *
 * This is called when the machine is rebooting or halting.  We assume that the
 * machine will be powered off, and the HC's internal state will be reset.
 * Don't bother to free memory.
 *
 * This will only ever be called with the main usb_hcd (the USB3 roothub).
 */
void xhci_shutdown(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);

	spin_lock_irq(&xhci->lock);
	xhci_halt(xhci);
	spin_unlock_irq(&xhci->lock);

	xhci_cleanup_msix(xhci);

	xhci_dbg(xhci, "xhci_shutdown completed - status = %x\n",
		    xhci_readl(xhci, &xhci->op_regs->status));
}

#ifdef CONFIG_PM
static void xhci_save_registers(struct xhci_hcd *xhci)
{
	xhci->s3.command = xhci_readl(xhci, &xhci->op_regs->command);
	xhci->s3.dev_nt = xhci_readl(xhci, &xhci->op_regs->dev_notification);
	xhci->s3.dcbaa_ptr = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
	xhci->s3.config_reg = xhci_readl(xhci, &xhci->op_regs->config_reg);
	xhci->s3.irq_pending = xhci_readl(xhci, &xhci->ir_set->irq_pending);
	xhci->s3.irq_control = xhci_readl(xhci, &xhci->ir_set->irq_control);
	xhci->s3.erst_size = xhci_readl(xhci, &xhci->ir_set->erst_size);
	xhci->s3.erst_base = xhci_read_64(xhci, &xhci->ir_set->erst_base);
	xhci->s3.erst_dequeue = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
}

static void xhci_restore_registers(struct xhci_hcd *xhci)
{
	xhci_writel(xhci, xhci->s3.command, &xhci->op_regs->command);
	xhci_writel(xhci, xhci->s3.dev_nt, &xhci->op_regs->dev_notification);
	xhci_write_64(xhci, xhci->s3.dcbaa_ptr, &xhci->op_regs->dcbaa_ptr);
	xhci_writel(xhci, xhci->s3.config_reg, &xhci->op_regs->config_reg);
	xhci_writel(xhci, xhci->s3.irq_pending, &xhci->ir_set->irq_pending);
	xhci_writel(xhci, xhci->s3.irq_control, &xhci->ir_set->irq_control);
	xhci_writel(xhci, xhci->s3.erst_size, &xhci->ir_set->erst_size);
	xhci_write_64(xhci, xhci->s3.erst_base, &xhci->ir_set->erst_base);
}

static void xhci_set_cmd_ring_deq(struct xhci_hcd *xhci)
{
	u64	val_64;

	/* step 2: initialize command ring buffer */
	val_64 = xhci_read_64(xhci, &xhci->op_regs->cmd_ring);
	val_64 = (val_64 & (u64) CMD_RING_RSVD_BITS) |
		(xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
				      xhci->cmd_ring->dequeue) &
		 (u64) ~CMD_RING_RSVD_BITS) |
		xhci->cmd_ring->cycle_state;
	xhci_dbg(xhci, "// Setting command ring address to 0x%llx\n",
			(long unsigned long) val_64);
	xhci_write_64(xhci, val_64, &xhci->op_regs->cmd_ring);
}

/*
 * The whole command ring must be cleared to zero when we suspend the host.
 *
 * The host doesn't save the command ring pointer in the suspend well, so we
 * need to re-program it on resume.  Unfortunately, the pointer must be 64-byte
 * aligned, because of the reserved bits in the command ring dequeue pointer
 * register.  Therefore, we can't just set the dequeue pointer back in the
 * middle of the ring (TRBs are 16-byte aligned).
 */
static void xhci_clear_command_ring(struct xhci_hcd *xhci)
{
	struct xhci_ring *ring;
	struct xhci_segment *seg;

	ring = xhci->cmd_ring;
	seg = ring->deq_seg;
	do {
		memset(seg->trbs, 0, SEGMENT_SIZE);
		seg = seg->next;
	} while (seg != ring->deq_seg);

	/* Reset the software enqueue and dequeue pointers */
	ring->deq_seg = ring->first_seg;
	ring->dequeue = ring->first_seg->trbs;
	ring->enq_seg = ring->deq_seg;
	ring->enqueue = ring->dequeue;

	/*
	 * Ring is now zeroed, so the HW should look for change of ownership
	 * when the cycle bit is set to 1.
	 */
	ring->cycle_state = 1;

	/*
	 * Reset the hardware dequeue pointer.
	 * Yes, this will need to be re-written after resume, but we're paranoid
	 * and want to make sure the hardware doesn't access bogus memory
	 * because, say, the BIOS or an SMI started the host without changing
	 * the command ring pointers.
	 */
	xhci_set_cmd_ring_deq(xhci);
}

/*
 * Stop HC (not bus-specific)
 *
 * This is called when the machine transition into S3/S4 mode.
 *
 */
int xhci_suspend(struct xhci_hcd *xhci)
{
	int			rc = 0;
	struct usb_hcd		*hcd = xhci_to_hcd(xhci);
	u32			command;
	int			i;

	spin_lock_irq(&xhci->lock);
	clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
	clear_bit(HCD_FLAG_HW_ACCESSIBLE, &xhci->shared_hcd->flags);
	/* step 1: stop endpoint */
	/* skipped assuming that port suspend has done */

	/* step 2: clear Run/Stop bit */
	command = xhci_readl(xhci, &xhci->op_regs->command);
	command &= ~CMD_RUN;
	xhci_writel(xhci, command, &xhci->op_regs->command);
	if (handshake(xhci, &xhci->op_regs->status,
		      STS_HALT, STS_HALT, 100*100)) {
		xhci_warn(xhci, "WARN: xHC CMD_RUN timeout\n");
		spin_unlock_irq(&xhci->lock);
		return -ETIMEDOUT;
	}
	xhci_clear_command_ring(xhci);

	/* step 3: save registers */
	xhci_save_registers(xhci);

	/* step 4: set CSS flag */
	command = xhci_readl(xhci, &xhci->op_regs->command);
	command |= CMD_CSS;
	xhci_writel(xhci, command, &xhci->op_regs->command);
	if (handshake(xhci, &xhci->op_regs->status, STS_SAVE, 0, 10*100)) {
		xhci_warn(xhci, "WARN: xHC CMD_CSS timeout\n");
		spin_unlock_irq(&xhci->lock);
		return -ETIMEDOUT;
	}
	spin_unlock_irq(&xhci->lock);

	/* step 5: remove core well power */
	/* synchronize irq when using MSI-X */
	if (xhci->msix_entries) {
		for (i = 0; i < xhci->msix_count; i++)
			synchronize_irq(xhci->msix_entries[i].vector);
	}

	return rc;
}

/*
 * start xHC (not bus-specific)
 *
 * This is called when the machine transition from S3/S4 mode.
 *
 */
int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
{
	u32			command, temp = 0;
	struct usb_hcd		*hcd = xhci_to_hcd(xhci);
	struct usb_hcd		*secondary_hcd;
	int			retval;

	/* Wait a bit if either of the roothubs need to settle from the
	 * transition into bus suspend.
	 */
	if (time_before(jiffies, xhci->bus_state[0].next_statechange) ||
			time_before(jiffies,
				xhci->bus_state[1].next_statechange))
		msleep(100);

	spin_lock_irq(&xhci->lock);

	if (!hibernated) {
		/* step 1: restore register */
		xhci_restore_registers(xhci);
		/* step 2: initialize command ring buffer */
		xhci_set_cmd_ring_deq(xhci);
		/* step 3: restore state and start state*/
		/* step 3: set CRS flag */
		command = xhci_readl(xhci, &xhci->op_regs->command);
		command |= CMD_CRS;
		xhci_writel(xhci, command, &xhci->op_regs->command);
		if (handshake(xhci, &xhci->op_regs->status,
			      STS_RESTORE, 0, 10*100)) {
			xhci_dbg(xhci, "WARN: xHC CMD_CSS timeout\n");
			spin_unlock_irq(&xhci->lock);
			return -ETIMEDOUT;
		}
		temp = xhci_readl(xhci, &xhci->op_regs->status);
	}

	/* If restore operation fails, re-initialize the HC during resume */
	if ((temp & STS_SRE) || hibernated) {
		/* Let the USB core know _both_ roothubs lost power. */
		usb_root_hub_lost_power(xhci->main_hcd->self.root_hub);
		usb_root_hub_lost_power(xhci->shared_hcd->self.root_hub);

		xhci_dbg(xhci, "Stop HCD\n");
		xhci_halt(xhci);
		xhci_reset(xhci);
		spin_unlock_irq(&xhci->lock);
		xhci_cleanup_msix(xhci);

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
		/* Tell the event ring poll function not to reschedule */
		xhci->zombie = 1;
		del_timer_sync(&xhci->event_ring_timer);
#endif

		xhci_dbg(xhci, "// Disabling event ring interrupts\n");
		temp = xhci_readl(xhci, &xhci->op_regs->status);
		xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
		temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
		xhci_writel(xhci, ER_IRQ_DISABLE(temp),
				&xhci->ir_set->irq_pending);
		xhci_print_ir_set(xhci, 0);

		xhci_dbg(xhci, "cleaning up memory\n");
		xhci_mem_cleanup(xhci);
		xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
			    xhci_readl(xhci, &xhci->op_regs->status));

		/* USB core calls the PCI reinit and start functions twice:
		 * first with the primary HCD, and then with the secondary HCD.
		 * If we don't do the same, the host will never be started.
		 */
		if (!usb_hcd_is_primary_hcd(hcd))
			secondary_hcd = hcd;
		else
			secondary_hcd = xhci->shared_hcd;

		xhci_dbg(xhci, "Initialize the xhci_hcd\n");
		retval = xhci_init(hcd->primary_hcd);
		if (retval)
			return retval;
		xhci_dbg(xhci, "Start the primary HCD\n");
		retval = xhci_run(hcd->primary_hcd);
		if (retval)
			goto failed_restart;

		xhci_dbg(xhci, "Start the secondary HCD\n");
		retval = xhci_run(secondary_hcd);
		if (!retval) {
			set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
			set_bit(HCD_FLAG_HW_ACCESSIBLE,
					&xhci->shared_hcd->flags);
		}
failed_restart:
		hcd->state = HC_STATE_SUSPENDED;
		xhci->shared_hcd->state = HC_STATE_SUSPENDED;
		return retval;
	}

	/* step 4: set Run/Stop bit */
	command = xhci_readl(xhci, &xhci->op_regs->command);
	command |= CMD_RUN;
	xhci_writel(xhci, command, &xhci->op_regs->command);
	handshake(xhci, &xhci->op_regs->status, STS_HALT,
		  0, 250 * 1000);

	/* step 5: walk topology and initialize portsc,
	 * portpmsc and portli
	 */
	/* this is done in bus_resume */

	/* step 6: restart each of the previously
	 * Running endpoints by ringing their doorbells
	 */

	set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
	set_bit(HCD_FLAG_HW_ACCESSIBLE, &xhci->shared_hcd->flags);

	spin_unlock_irq(&xhci->lock);
	return 0;
}
#endif	/* CONFIG_PM */

/*-------------------------------------------------------------------------*/

/**
 * xhci_get_endpoint_index - Used for passing endpoint bitmasks between the core and
 * HCDs.  Find the index for an endpoint given its descriptor.  Use the return
 * value to right shift 1 for the bitmask.
 *
 * Index  = (epnum * 2) + direction - 1,
 * where direction = 0 for OUT, 1 for IN.
 * For control endpoints, the IN index is used (OUT index is unused), so
 * index = (epnum * 2) + direction - 1 = (epnum * 2) + 1 - 1 = (epnum * 2)
 */
unsigned int xhci_get_endpoint_index(struct usb_endpoint_descriptor *desc)
{
	unsigned int index;
	if (usb_endpoint_xfer_control(desc))
		index = (unsigned int) (usb_endpoint_num(desc)*2);
	else
		index = (unsigned int) (usb_endpoint_num(desc)*2) +
			(usb_endpoint_dir_in(desc) ? 1 : 0) - 1;
	return index;
}

/* Find the flag for this endpoint (for use in the control context).  Use the
 * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
 * bit 1, etc.
 */
unsigned int xhci_get_endpoint_flag(struct usb_endpoint_descriptor *desc)
{
	return 1 << (xhci_get_endpoint_index(desc) + 1);
}

/* Find the flag for this endpoint (for use in the control context).  Use the
 * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
 * bit 1, etc.
 */
unsigned int xhci_get_endpoint_flag_from_index(unsigned int ep_index)
{
	return 1 << (ep_index + 1);
}

/* Compute the last valid endpoint context index.  Basically, this is the
 * endpoint index plus one.  For slot contexts with more than valid endpoint,
 * we find the most significant bit set in the added contexts flags.
 * e.g. ep 1 IN (with epnum 0x81) => added_ctxs = 0b1000
 * fls(0b1000) = 4, but the endpoint context index is 3, so subtract one.
 */
unsigned int xhci_last_valid_endpoint(u32 added_ctxs)
{
	return fls(added_ctxs) - 1;
}

/* Returns 1 if the arguments are OK;
 * returns 0 this is a root hub; returns -EINVAL for NULL pointers.
 */
static int xhci_check_args(struct usb_hcd *hcd, struct usb_device *udev,
		struct usb_host_endpoint *ep, int check_ep, bool check_virt_dev,
		const char *func) {
	struct xhci_hcd	*xhci;
	struct xhci_virt_device	*virt_dev;

	if (!hcd || (check_ep && !ep) || !udev) {
		printk(KERN_DEBUG "xHCI %s called with invalid args\n",
				func);
		return -EINVAL;
	}
	if (!udev->parent) {
		printk(KERN_DEBUG "xHCI %s called for root hub\n",
				func);
		return 0;
	}

	if (check_virt_dev) {
		xhci = hcd_to_xhci(hcd);
		if (!udev->slot_id || !xhci->devs
			|| !xhci->devs[udev->slot_id]) {
			printk(KERN_DEBUG "xHCI %s called with unaddressed "
						"device\n", func);
			return -EINVAL;
		}

		virt_dev = xhci->devs[udev->slot_id];
		if (virt_dev->udev != udev) {
			printk(KERN_DEBUG "xHCI %s called with udev and "
					  "virt_dev does not match\n", func);
			return -EINVAL;
		}
	}

	return 1;
}

static int xhci_configure_endpoint(struct xhci_hcd *xhci,
		struct usb_device *udev, struct xhci_command *command,
		bool ctx_change, bool must_succeed);

/*
 * Full speed devices may have a max packet size greater than 8 bytes, but the
 * USB core doesn't know that until it reads the first 8 bytes of the
 * descriptor.  If the usb_device's max packet size changes after that point,
 * we need to issue an evaluate context command and wait on it.
 */
static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
		unsigned int ep_index, struct urb *urb)
{
	struct xhci_container_ctx *in_ctx;
	struct xhci_container_ctx *out_ctx;
	struct xhci_input_control_ctx *ctrl_ctx;
	struct xhci_ep_ctx *ep_ctx;
	int max_packet_size;
	int hw_max_packet_size;
	int ret = 0;

	out_ctx = xhci->devs[slot_id]->out_ctx;
	ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
	hw_max_packet_size = MAX_PACKET_DECODED(le32_to_cpu(ep_ctx->ep_info2));
	max_packet_size = le16_to_cpu(urb->dev->ep0.desc.wMaxPacketSize);
	if (hw_max_packet_size != max_packet_size) {
		xhci_dbg(xhci, "Max Packet Size for ep 0 changed.\n");
		xhci_dbg(xhci, "Max packet size in usb_device = %d\n",
				max_packet_size);
		xhci_dbg(xhci, "Max packet size in xHCI HW = %d\n",
				hw_max_packet_size);
		xhci_dbg(xhci, "Issuing evaluate context command.\n");

		/* Set up the modified control endpoint 0 */
		xhci_endpoint_copy(xhci, xhci->devs[slot_id]->in_ctx,
				xhci->devs[slot_id]->out_ctx, ep_index);
		in_ctx = xhci->devs[slot_id]->in_ctx;
		ep_ctx = xhci_get_ep_ctx(xhci, in_ctx, ep_index);
		ep_ctx->ep_info2 &= cpu_to_le32(~MAX_PACKET_MASK);
		ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet_size));

		/* Set up the input context flags for the command */
		/* FIXME: This won't work if a non-default control endpoint
		 * changes max packet sizes.
		 */
		ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
		ctrl_ctx->add_flags = cpu_to_le32(EP0_FLAG);
		ctrl_ctx->drop_flags = 0;

		xhci_dbg(xhci, "Slot %d input context\n", slot_id);
		xhci_dbg_ctx(xhci, in_ctx, ep_index);
		xhci_dbg(xhci, "Slot %d output context\n", slot_id);
		xhci_dbg_ctx(xhci, out_ctx, ep_index);

		ret = xhci_configure_endpoint(xhci, urb->dev, NULL,
				true, false);

		/* Clean up the input context for later use by bandwidth
		 * functions.
		 */
		ctrl_ctx->add_flags = cpu_to_le32(SLOT_FLAG);
	}
	return ret;
}

/*
 * non-error returns are a promise to giveback() the urb later
 * we drop ownership so next owner (or urb unlink) can get it
 */
int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	unsigned long flags;
	int ret = 0;
	unsigned int slot_id, ep_index;
	struct urb_priv	*urb_priv;
	int size, i;

	if (!urb || xhci_check_args(hcd, urb->dev, urb->ep,
					true, true, __func__) <= 0)
		return -EINVAL;

	slot_id = urb->dev->slot_id;
	ep_index = xhci_get_endpoint_index(&urb->ep->desc);

	if (!HCD_HW_ACCESSIBLE(hcd)) {
		if (!in_interrupt())
			xhci_dbg(xhci, "urb submitted during PCI suspend\n");
		ret = -ESHUTDOWN;
		goto exit;
	}

	if (usb_endpoint_xfer_isoc(&urb->ep->desc))
		size = urb->number_of_packets;
	else
		size = 1;

	urb_priv = kzalloc(sizeof(struct urb_priv) +
				  size * sizeof(struct xhci_td *), mem_flags);
	if (!urb_priv)
		return -ENOMEM;

	for (i = 0; i < size; i++) {
		urb_priv->td[i] = kzalloc(sizeof(struct xhci_td), mem_flags);
		if (!urb_priv->td[i]) {
			urb_priv->length = i;
			xhci_urb_free_priv(xhci, urb_priv);
			return -ENOMEM;
		}
	}

	urb_priv->length = size;
	urb_priv->td_cnt = 0;
	urb->hcpriv = urb_priv;

	if (usb_endpoint_xfer_control(&urb->ep->desc)) {
		/* Check to see if the max packet size for the default control
		 * endpoint changed during FS device enumeration
		 */
		if (urb->dev->speed == USB_SPEED_FULL) {
			ret = xhci_check_maxpacket(xhci, slot_id,
					ep_index, urb);
			if (ret < 0)
				return ret;
		}

		/* We have a spinlock and interrupts disabled, so we must pass
		 * atomic context to this function, which may allocate memory.
		 */
		spin_lock_irqsave(&xhci->lock, flags);
		if (xhci->xhc_state & XHCI_STATE_DYING)
			goto dying;
		ret = xhci_queue_ctrl_tx(xhci, GFP_ATOMIC, urb,
				slot_id, ep_index);
		spin_unlock_irqrestore(&xhci->lock, flags);
	} else if (usb_endpoint_xfer_bulk(&urb->ep->desc)) {
		spin_lock_irqsave(&xhci->lock, flags);
		if (xhci->xhc_state & XHCI_STATE_DYING)
			goto dying;
		if (xhci->devs[slot_id]->eps[ep_index].ep_state &
				EP_GETTING_STREAMS) {
			xhci_warn(xhci, "WARN: Can't enqueue URB while bulk ep "
					"is transitioning to using streams.\n");
			ret = -EINVAL;
		} else if (xhci->devs[slot_id]->eps[ep_index].ep_state &
				EP_GETTING_NO_STREAMS) {
			xhci_warn(xhci, "WARN: Can't enqueue URB while bulk ep "
					"is transitioning to "
					"not having streams.\n");
			ret = -EINVAL;
		} else {
			ret = xhci_queue_bulk_tx(xhci, GFP_ATOMIC, urb,
					slot_id, ep_index);
		}
		spin_unlock_irqrestore(&xhci->lock, flags);
	} else if (usb_endpoint_xfer_int(&urb->ep->desc)) {
		spin_lock_irqsave(&xhci->lock, flags);
		if (xhci->xhc_state & XHCI_STATE_DYING)
			goto dying;
		ret = xhci_queue_intr_tx(xhci, GFP_ATOMIC, urb,
				slot_id, ep_index);
		spin_unlock_irqrestore(&xhci->lock, flags);
	} else {
		spin_lock_irqsave(&xhci->lock, flags);
		if (xhci->xhc_state & XHCI_STATE_DYING)
			goto dying;
		ret = xhci_queue_isoc_tx_prepare(xhci, GFP_ATOMIC, urb,
				slot_id, ep_index);
		spin_unlock_irqrestore(&xhci->lock, flags);
	}
exit:
	return ret;
dying:
	xhci_urb_free_priv(xhci, urb_priv);
	urb->hcpriv = NULL;
	xhci_dbg(xhci, "Ep 0x%x: URB %p submitted for "
			"non-responsive xHCI host.\n",
			urb->ep->desc.bEndpointAddress, urb);
	spin_unlock_irqrestore(&xhci->lock, flags);
	return -ESHUTDOWN;
}

/* Get the right ring for the given URB.
 * If the endpoint supports streams, boundary check the URB's stream ID.
 * If the endpoint doesn't support streams, return the singular endpoint ring.
 */
static struct xhci_ring *xhci_urb_to_transfer_ring(struct xhci_hcd *xhci,
		struct urb *urb)
{
	unsigned int slot_id;
	unsigned int ep_index;
	unsigned int stream_id;
	struct xhci_virt_ep *ep;

	slot_id = urb->dev->slot_id;
	ep_index = xhci_get_endpoint_index(&urb->ep->desc);
	stream_id = urb->stream_id;
	ep = &xhci->devs[slot_id]->eps[ep_index];
	/* Common case: no streams */
	if (!(ep->ep_state & EP_HAS_STREAMS))
		return ep->ring;

	if (stream_id == 0) {
		xhci_warn(xhci,
				"WARN: Slot ID %u, ep index %u has streams, "
				"but URB has no stream ID.\n",
				slot_id, ep_index);
		return NULL;
	}

	if (stream_id < ep->stream_info->num_streams)
		return ep->stream_info->stream_rings[stream_id];

	xhci_warn(xhci,
			"WARN: Slot ID %u, ep index %u has "
			"stream IDs 1 to %u allocated, "
			"but stream ID %u is requested.\n",
			slot_id, ep_index,
			ep->stream_info->num_streams - 1,
			stream_id);
	return NULL;
}

/*
 * Remove the URB's TD from the endpoint ring.  This may cause the HC to stop
 * USB transfers, potentially stopping in the middle of a TRB buffer.  The HC
 * should pick up where it left off in the TD, unless a Set Transfer Ring
 * Dequeue Pointer is issued.
 *
 * The TRBs that make up the buffers for the canceled URB will be "removed" from
 * the ring.  Since the ring is a contiguous structure, they can't be physically
 * removed.  Instead, there are two options:
 *
 *  1) If the HC is in the middle of processing the URB to be canceled, we
 *     simply move the ring's dequeue pointer past those TRBs using the Set
 *     Transfer Ring Dequeue Pointer command.  This will be the common case,
 *     when drivers timeout on the last submitted URB and attempt to cancel.
 *
 *  2) If the HC is in the middle of a different TD, we turn the TRBs into a
 *     series of 1-TRB transfer no-op TDs.  (No-ops shouldn't be chained.)  The
 *     HC will need to invalidate the any TRBs it has cached after the stop
 *     endpoint command, as noted in the xHCI 0.95 errata.
 *
 *  3) The TD may have completed by the time the Stop Endpoint Command
 *     completes, so software needs to handle that case too.
 *
 * This function should protect against the TD enqueueing code ringing the
 * doorbell while this code is waiting for a Stop Endpoint command to complete.
 * It also needs to account for multiple cancellations on happening at the same
 * time for the same endpoint.
 *
 * Note that this function can be called in any context, or so says
 * usb_hcd_unlink_urb()
 */
int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
{
	unsigned long flags;
	int ret, i;
	u32 temp;
	struct xhci_hcd *xhci;
	struct urb_priv	*urb_priv;
	struct xhci_td *td;
	unsigned int ep_index;
	struct xhci_ring *ep_ring;
	struct xhci_virt_ep *ep;

	xhci = hcd_to_xhci(hcd);
	spin_lock_irqsave(&xhci->lock, flags);
	/* Make sure the URB hasn't completed or been unlinked already */
	ret = usb_hcd_check_unlink_urb(hcd, urb, status);
	if (ret || !urb->hcpriv)
		goto done;
	temp = xhci_readl(xhci, &xhci->op_regs->status);
	if (temp == 0xffffffff || (xhci->xhc_state & XHCI_STATE_HALTED)) {
		xhci_dbg(xhci, "HW died, freeing TD.\n");
		urb_priv = urb->hcpriv;

		usb_hcd_unlink_urb_from_ep(hcd, urb);
		spin_unlock_irqrestore(&xhci->lock, flags);
		usb_hcd_giveback_urb(hcd, urb, -ESHUTDOWN);
		xhci_urb_free_priv(xhci, urb_priv);
		return ret;
	}
	if (xhci->xhc_state & XHCI_STATE_DYING) {
		xhci_dbg(xhci, "Ep 0x%x: URB %p to be canceled on "
				"non-responsive xHCI host.\n",
				urb->ep->desc.bEndpointAddress, urb);
		/* Let the stop endpoint command watchdog timer (which set this
		 * state) finish cleaning up the endpoint TD lists.  We must
		 * have caught it in the middle of dropping a lock and giving
		 * back an URB.
		 */
		goto done;
	}

	xhci_dbg(xhci, "Cancel URB %p\n", urb);
	xhci_dbg(xhci, "Event ring:\n");
	xhci_debug_ring(xhci, xhci->event_ring);
	ep_index = xhci_get_endpoint_index(&urb->ep->desc);
	ep = &xhci->devs[urb->dev->slot_id]->eps[ep_index];
	ep_ring = xhci_urb_to_transfer_ring(xhci, urb);
	if (!ep_ring) {
		ret = -EINVAL;
		goto done;
	}

	xhci_dbg(xhci, "Endpoint ring:\n");
	xhci_debug_ring(xhci, ep_ring);

	urb_priv = urb->hcpriv;

	for (i = urb_priv->td_cnt; i < urb_priv->length; i++) {
		td = urb_priv->td[i];
		list_add_tail(&td->cancelled_td_list, &ep->cancelled_td_list);
	}

	/* Queue a stop endpoint command, but only if this is
	 * the first cancellation to be handled.
	 */
	if (!(ep->ep_state & EP_HALT_PENDING)) {
		ep->ep_state |= EP_HALT_PENDING;
		ep->stop_cmds_pending++;
		ep->stop_cmd_timer.expires = jiffies +
			XHCI_STOP_EP_CMD_TIMEOUT * HZ;
		add_timer(&ep->stop_cmd_timer);
		xhci_queue_stop_endpoint(xhci, urb->dev->slot_id, ep_index, 0);
		xhci_ring_cmd_db(xhci);
	}
done:
	spin_unlock_irqrestore(&xhci->lock, flags);
	return ret;
}

/* Drop an endpoint from a new bandwidth configuration for this device.
 * Only one call to this function is allowed per endpoint before
 * check_bandwidth() or reset_bandwidth() must be called.
 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
 * add the endpoint to the schedule with possibly new parameters denoted by a
 * different endpoint descriptor in usb_host_endpoint.
 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
 * not allowed.
 *
 * The USB core will not allow URBs to be queued to an endpoint that is being
 * disabled, so there's no need for mutual exclusion to protect
 * the xhci->devs[slot_id] structure.
 */
int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
		struct usb_host_endpoint *ep)
{
	struct xhci_hcd *xhci;
	struct xhci_container_ctx *in_ctx, *out_ctx;
	struct xhci_input_control_ctx *ctrl_ctx;
	struct xhci_slot_ctx *slot_ctx;
	unsigned int last_ctx;
	unsigned int ep_index;
	struct xhci_ep_ctx *ep_ctx;
	u32 drop_flag;
	u32 new_add_flags, new_drop_flags, new_slot_info;
	int ret;

	ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
	if (ret <= 0)
		return ret;
	xhci = hcd_to_xhci(hcd);
	if (xhci->xhc_state & XHCI_STATE_DYING)
		return -ENODEV;

	xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
	drop_flag = xhci_get_endpoint_flag(&ep->desc);
	if (drop_flag == SLOT_FLAG || drop_flag == EP0_FLAG) {
		xhci_dbg(xhci, "xHCI %s - can't drop slot or ep 0 %#x\n",
				__func__, drop_flag);
		return 0;
	}

	in_ctx = xhci->devs[udev->slot_id]->in_ctx;
	out_ctx = xhci->devs[udev->slot_id]->out_ctx;
	ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
	ep_index = xhci_get_endpoint_index(&ep->desc);
	ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
	/* If the HC already knows the endpoint is disabled,
	 * or the HCD has noted it is disabled, ignore this request
	 */
	if ((le32_to_cpu(ep_ctx->ep_info) & EP_STATE_MASK) ==
	    EP_STATE_DISABLED ||
	    le32_to_cpu(ctrl_ctx->drop_flags) &
	    xhci_get_endpoint_flag(&ep->desc)) {
		xhci_warn(xhci, "xHCI %s called with disabled ep %p\n",
				__func__, ep);
		return 0;
	}

	ctrl_ctx->drop_flags |= cpu_to_le32(drop_flag);
	new_drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);

	ctrl_ctx->add_flags &= cpu_to_le32(~drop_flag);
	new_add_flags = le32_to_cpu(ctrl_ctx->add_flags);

	last_ctx = xhci_last_valid_endpoint(le32_to_cpu(ctrl_ctx->add_flags));
	slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
	/* Update the last valid endpoint context, if we deleted the last one */
	if ((le32_to_cpu(slot_ctx->dev_info) & LAST_CTX_MASK) >
	    LAST_CTX(last_ctx)) {
		slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
		slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(last_ctx));
	}
	new_slot_info = le32_to_cpu(slot_ctx->dev_info);

	xhci_endpoint_zero(xhci, xhci->devs[udev->slot_id], ep);

	xhci_dbg(xhci, "drop ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
			(unsigned int) ep->desc.bEndpointAddress,
			udev->slot_id,
			(unsigned int) new_drop_flags,
			(unsigned int) new_add_flags,
			(unsigned int) new_slot_info);
	return 0;
}

/* Add an endpoint to a new possible bandwidth configuration for this device.
 * Only one call to this function is allowed per endpoint before
 * check_bandwidth() or reset_bandwidth() must be called.
 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
 * add the endpoint to the schedule with possibly new parameters denoted by a
 * different endpoint descriptor in usb_host_endpoint.
 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
 * not allowed.
 *
 * The USB core will not allow URBs to be queued to an endpoint until the
 * configuration or alt setting is installed in the device, so there's no need
 * for mutual exclusion to protect the xhci->devs[slot_id] structure.
 */
int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
		struct usb_host_endpoint *ep)
{
	struct xhci_hcd *xhci;
	struct xhci_container_ctx *in_ctx, *out_ctx;
	unsigned int ep_index;
	struct xhci_ep_ctx *ep_ctx;
	struct xhci_slot_ctx *slot_ctx;
	struct xhci_input_control_ctx *ctrl_ctx;
	u32 added_ctxs;
	unsigned int last_ctx;
	u32 new_add_flags, new_drop_flags, new_slot_info;
	int ret = 0;

	ret = xhci_check_args(hcd, udev, ep, 1, true, __func__);
	if (ret <= 0) {
		/* So we won't queue a reset ep command for a root hub */
		ep->hcpriv = NULL;
		return ret;
	}
	xhci = hcd_to_xhci(hcd);
	if (xhci->xhc_state & XHCI_STATE_DYING)
		return -ENODEV;

	added_ctxs = xhci_get_endpoint_flag(&ep->desc);
	last_ctx = xhci_last_valid_endpoint(added_ctxs);
	if (added_ctxs == SLOT_FLAG || added_ctxs == EP0_FLAG) {
		/* FIXME when we have to issue an evaluate endpoint command to
		 * deal with ep0 max packet size changing once we get the
		 * descriptors
		 */
		xhci_dbg(xhci, "xHCI %s - can't add slot or ep 0 %#x\n",
				__func__, added_ctxs);
		return 0;
	}

	in_ctx = xhci->devs[udev->slot_id]->in_ctx;
	out_ctx = xhci->devs[udev->slot_id]->out_ctx;
	ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
	ep_index = xhci_get_endpoint_index(&ep->desc);
	ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
	/* If the HCD has already noted the endpoint is enabled,
	 * ignore this request.
	 */
	if (le32_to_cpu(ctrl_ctx->add_flags) &
	    xhci_get_endpoint_flag(&ep->desc)) {
		xhci_warn(xhci, "xHCI %s called with enabled ep %p\n",
				__func__, ep);
		return 0;
	}

	/*
	 * Configuration and alternate setting changes must be done in
	 * process context, not interrupt context (or so documenation
	 * for usb_set_interface() and usb_set_configuration() claim).
	 */
	if (xhci_endpoint_init(xhci, xhci->devs[udev->slot_id],
				udev, ep, GFP_NOIO) < 0) {
		dev_dbg(&udev->dev, "%s - could not initialize ep %#x\n",
				__func__, ep->desc.bEndpointAddress);
		return -ENOMEM;
	}

	ctrl_ctx->add_flags |= cpu_to_le32(added_ctxs);
	new_add_flags = le32_to_cpu(ctrl_ctx->add_flags);

	/* If xhci_endpoint_disable() was called for this endpoint, but the
	 * xHC hasn't been notified yet through the check_bandwidth() call,
	 * this re-adds a new state for the endpoint from the new endpoint
	 * descriptors.  We must drop and re-add this endpoint, so we leave the
	 * drop flags alone.
	 */
	new_drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);

	slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
	/* Update the last valid endpoint context, if we just added one past */
	if ((le32_to_cpu(slot_ctx->dev_info) & LAST_CTX_MASK) <
	    LAST_CTX(last_ctx)) {
		slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
		slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(last_ctx));
	}
	new_slot_info = le32_to_cpu(slot_ctx->dev_info);

	/* Store the usb_device pointer for later use */
	ep->hcpriv = udev;

	xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
			(unsigned int) ep->desc.bEndpointAddress,
			udev->slot_id,
			(unsigned int) new_drop_flags,
			(unsigned int) new_add_flags,
			(unsigned int) new_slot_info);
	return 0;
}

static void xhci_zero_in_ctx(struct xhci_hcd *xhci, struct xhci_virt_device *virt_dev)
{
	struct xhci_input_control_ctx *ctrl_ctx;
	struct xhci_ep_ctx *ep_ctx;
	struct xhci_slot_ctx *slot_ctx;
	int i;

	/* When a device's add flag and drop flag are zero, any subsequent
	 * configure endpoint command will leave that endpoint's state
	 * untouched.  Make sure we don't leave any old state in the input
	 * endpoint contexts.
	 */
	ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
	ctrl_ctx->drop_flags = 0;
	ctrl_ctx->add_flags = 0;
	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
	slot_ctx->dev_info &= cpu_to_le32(~LAST_CTX_MASK);
	/* Endpoint 0 is always valid */
	slot_ctx->dev_info |= cpu_to_le32(LAST_CTX(1));
	for (i = 1; i < 31; ++i) {
		ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->in_ctx, i);
		ep_ctx->ep_info = 0;
		ep_ctx->ep_info2 = 0;
		ep_ctx->deq = 0;
		ep_ctx->tx_info = 0;
	}
}

static int xhci_configure_endpoint_result(struct xhci_hcd *xhci,
		struct usb_device *udev, u32 *cmd_status)
{
	int ret;

	switch (*cmd_status) {
	case COMP_ENOMEM:
		dev_warn(&udev->dev, "Not enough host controller resources "
				"for new device state.\n");
		ret = -ENOMEM;
		/* FIXME: can we allocate more resources for the HC? */
		break;
	case COMP_BW_ERR:
		dev_warn(&udev->dev, "Not enough bandwidth "
				"for new device state.\n");
		ret = -ENOSPC;
		/* FIXME: can we go back to the old state? */
		break;
	case COMP_TRB_ERR:
		/* the HCD set up something wrong */
		dev_warn(&udev->dev, "ERROR: Endpoint drop flag = 0, "
				"add flag = 1, "
				"and endpoint is not disabled.\n");
		ret = -EINVAL;
		break;
	case COMP_SUCCESS:
		dev_dbg(&udev->dev, "Successful Endpoint Configure command\n");
		ret = 0;
		break;
	default:
		xhci_err(xhci, "ERROR: unexpected command completion "
				"code 0x%x.\n", *cmd_status);
		ret = -EINVAL;
		break;
	}
	return ret;
}

static int xhci_evaluate_context_result(struct xhci_hcd *xhci,
		struct usb_device *udev, u32 *cmd_status)
{
	int ret;
	struct xhci_virt_device *virt_dev = xhci->devs[udev->slot_id];

	switch (*cmd_status) {
	case COMP_EINVAL:
		dev_warn(&udev->dev, "WARN: xHCI driver setup invalid evaluate "
				"context command.\n");
		ret = -EINVAL;
		break;
	case COMP_EBADSLT:
		dev_warn(&udev->dev, "WARN: slot not enabled for"
				"evaluate context command.\n");
	case COMP_CTX_STATE:
		dev_warn(&udev->dev, "WARN: invalid context state for "
				"evaluate context command.\n");
		xhci_dbg_ctx(xhci, virt_dev->out_ctx, 1);
		ret = -EINVAL;
		break;
	case COMP_MEL_ERR:
		/* Max Exit Latency too large error */
		dev_warn(&udev->dev, "WARN: Max Exit Latency too large\n");
		ret = -EINVAL;
		break;
	case COMP_SUCCESS:
		dev_dbg(&udev->dev, "Successful evaluate context command\n");
		ret = 0;
		break;
	default:
		xhci_err(xhci, "ERROR: unexpected command completion "
				"code 0x%x.\n", *cmd_status);
		ret = -EINVAL;
		break;
	}
	return ret;
}

static u32 xhci_count_num_new_endpoints(struct xhci_hcd *xhci,
		struct xhci_container_ctx *in_ctx)
{
	struct xhci_input_control_ctx *ctrl_ctx;
	u32 valid_add_flags;
	u32 valid_drop_flags;

	ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
	/* Ignore the slot flag (bit 0), and the default control endpoint flag
	 * (bit 1).  The default control endpoint is added during the Address
	 * Device command and is never removed until the slot is disabled.
	 */
	valid_add_flags = ctrl_ctx->add_flags >> 2;
	valid_drop_flags = ctrl_ctx->drop_flags >> 2;

	/* Use hweight32 to count the number of ones in the add flags, or
	 * number of endpoints added.  Don't count endpoints that are changed
	 * (both added and dropped).
	 */
	return hweight32(valid_add_flags) -
		hweight32(valid_add_flags & valid_drop_flags);
}

static unsigned int xhci_count_num_dropped_endpoints(struct xhci_hcd *xhci,
		struct xhci_container_ctx *in_ctx)
{
	struct xhci_input_control_ctx *ctrl_ctx;
	u32 valid_add_flags;
	u32 valid_drop_flags;

	ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
	valid_add_flags = ctrl_ctx->add_flags >> 2;
	valid_drop_flags = ctrl_ctx->drop_flags >> 2;

	return hweight32(valid_drop_flags) -
		hweight32(valid_add_flags & valid_drop_flags);
}

/*
 * We need to reserve the new number of endpoints before the configure endpoint
 * command completes.  We can't subtract the dropped endpoints from the number
 * of active endpoints until the command completes because we can oversubscribe
 * the host in this case:
 *
 *  - the first configure endpoint command drops more endpoints than it adds
 *  - a second configure endpoint command that adds more endpoints is queued
 *  - the first configure endpoint command fails, so the config is unchanged
 *  - the second command may succeed, even though there isn't enough resources
 *
 * Must be called with xhci->lock held.
 */
static int xhci_reserve_host_resources(struct xhci_hcd *xhci,
		struct xhci_container_ctx *in_ctx)
{
	u32 added_eps;

	added_eps = xhci_count_num_new_endpoints(xhci, in_ctx);
	if (xhci->num_active_eps + added_eps > xhci->limit_active_eps) {
		xhci_dbg(xhci, "Not enough ep ctxs: "
				"%u active, need to add %u, limit is %u.\n",
				xhci->num_active_eps, added_eps,
				xhci->limit_active_eps);
		return -ENOMEM;
	}
	xhci->num_active_eps += added_eps;
	xhci_dbg(xhci, "Adding %u ep ctxs, %u now active.\n", added_eps,
			xhci->num_active_eps);
	return 0;
}

/*
 * The configure endpoint was failed by the xHC for some other reason, so we
 * need to revert the resources that failed configuration would have used.
 *
 * Must be called with xhci->lock held.
 */
static void xhci_free_host_resources(struct xhci_hcd *xhci,
		struct xhci_container_ctx *in_ctx)
{
	u32 num_failed_eps;

	num_failed_eps = xhci_count_num_new_endpoints(xhci, in_ctx);
	xhci->num_active_eps -= num_failed_eps;
	xhci_dbg(xhci, "Removing %u failed ep ctxs, %u now active.\n",
			num_failed_eps,
			xhci->num_active_eps);
}

/*
 * Now that the command has completed, clean up the active endpoint count by
 * subtracting out the endpoints that were dropped (but not changed).
 *
 * Must be called with xhci->lock held.
 */
static void xhci_finish_resource_reservation(struct xhci_hcd *xhci,
		struct xhci_container_ctx *in_ctx)
{
	u32 num_dropped_eps;

	num_dropped_eps = xhci_count_num_dropped_endpoints(xhci, in_ctx);
	xhci->num_active_eps -= num_dropped_eps;
	if (num_dropped_eps)
		xhci_dbg(xhci, "Removing %u dropped ep ctxs, %u now active.\n",
				num_dropped_eps,
				xhci->num_active_eps);
}

/* Issue a configure endpoint command or evaluate context command
 * and wait for it to finish.
 */
static int xhci_configure_endpoint(struct xhci_hcd *xhci,
		struct usb_device *udev,
		struct xhci_command *command,
		bool ctx_change, bool must_succeed)
{
	int ret;
	int timeleft;
	unsigned long flags;
	struct xhci_container_ctx *in_ctx;
	struct completion *cmd_completion;
	u32 *cmd_status;
	struct xhci_virt_device *virt_dev;

	spin_lock_irqsave(&xhci->lock, flags);
	virt_dev = xhci->devs[udev->slot_id];
	if (command) {
		in_ctx = command->in_ctx;
		if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK) &&
				xhci_reserve_host_resources(xhci, in_ctx)) {
			spin_unlock_irqrestore(&xhci->lock, flags);
			xhci_warn(xhci, "Not enough host resources, "
					"active endpoint contexts = %u\n",
					xhci->num_active_eps);
			return -ENOMEM;
		}

		cmd_completion = command->completion;
		cmd_status = &command->status;
		command->command_trb = xhci->cmd_ring->enqueue;

		/* Enqueue pointer can be left pointing to the link TRB,
		 * we must handle that
		 */
		if ((le32_to_cpu(command->command_trb->link.control)
		     & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK))
			command->command_trb =
				xhci->cmd_ring->enq_seg->next->trbs;

		list_add_tail(&command->cmd_list, &virt_dev->cmd_list);
	} else {
		in_ctx = virt_dev->in_ctx;
		if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK) &&
				xhci_reserve_host_resources(xhci, in_ctx)) {
			spin_unlock_irqrestore(&xhci->lock, flags);
			xhci_warn(xhci, "Not enough host resources, "
					"active endpoint contexts = %u\n",
					xhci->num_active_eps);
			return -ENOMEM;
		}
		cmd_completion = &virt_dev->cmd_completion;
		cmd_status = &virt_dev->cmd_status;
	}
	init_completion(cmd_completion);

	if (!ctx_change)
		ret = xhci_queue_configure_endpoint(xhci, in_ctx->dma,
				udev->slot_id, must_succeed);
	else
		ret = xhci_queue_evaluate_context(xhci, in_ctx->dma,
				udev->slot_id);
	if (ret < 0) {
		if (command)
			list_del(&command->cmd_list);
		if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK))
			xhci_free_host_resources(xhci, in_ctx);
		spin_unlock_irqrestore(&xhci->lock, flags);
		xhci_dbg(xhci, "FIXME allocate a new ring segment\n");
		return -ENOMEM;
	}
	xhci_ring_cmd_db(xhci);
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* Wait for the configure endpoint command to complete */
	timeleft = wait_for_completion_interruptible_timeout(
			cmd_completion,
			USB_CTRL_SET_TIMEOUT);
	if (timeleft <= 0) {
		xhci_warn(xhci, "%s while waiting for %s command\n",
				timeleft == 0 ? "Timeout" : "Signal",
				ctx_change == 0 ?
					"configure endpoint" :
					"evaluate context");
		/* FIXME cancel the configure endpoint command */
		return -ETIME;
	}

	if (!ctx_change)
		ret = xhci_configure_endpoint_result(xhci, udev, cmd_status);
	else
		ret = xhci_evaluate_context_result(xhci, udev, cmd_status);

	if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
		spin_lock_irqsave(&xhci->lock, flags);
		/* If the command failed, remove the reserved resources.
		 * Otherwise, clean up the estimate to include dropped eps.
		 */
		if (ret)
			xhci_free_host_resources(xhci, in_ctx);
		else
			xhci_finish_resource_reservation(xhci, in_ctx);
		spin_unlock_irqrestore(&xhci->lock, flags);
	}
	return ret;
}

/* Called after one or more calls to xhci_add_endpoint() or
 * xhci_drop_endpoint().  If this call fails, the USB core is expected
 * to call xhci_reset_bandwidth().
 *
 * Since we are in the middle of changing either configuration or
 * installing a new alt setting, the USB core won't allow URBs to be
 * enqueued for any endpoint on the old config or interface.  Nothing
 * else should be touching the xhci->devs[slot_id] structure, so we
 * don't need to take the xhci->lock for manipulating that.
 */
int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
	int i;
	int ret = 0;
	struct xhci_hcd *xhci;
	struct xhci_virt_device	*virt_dev;
	struct xhci_input_control_ctx *ctrl_ctx;
	struct xhci_slot_ctx *slot_ctx;

	ret = xhci_check_args(hcd, udev, NULL, 0, true, __func__);
	if (ret <= 0)
		return ret;
	xhci = hcd_to_xhci(hcd);
	if (xhci->xhc_state & XHCI_STATE_DYING)
		return -ENODEV;

	xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
	virt_dev = xhci->devs[udev->slot_id];

	/* See section 4.6.6 - A0 = 1; A1 = D0 = D1 = 0 */
	ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
	ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
	ctrl_ctx->add_flags &= cpu_to_le32(~EP0_FLAG);
	ctrl_ctx->drop_flags &= cpu_to_le32(~(SLOT_FLAG | EP0_FLAG));
	xhci_dbg(xhci, "New Input Control Context:\n");
	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
	xhci_dbg_ctx(xhci, virt_dev->in_ctx,
		     LAST_CTX_TO_EP_NUM(le32_to_cpu(slot_ctx->dev_info)));

	ret = xhci_configure_endpoint(xhci, udev, NULL,
			false, false);
	if (ret) {
		/* Callee should call reset_bandwidth() */
		return ret;
	}

	xhci_dbg(xhci, "Output context after successful config ep cmd:\n");
	xhci_dbg_ctx(xhci, virt_dev->out_ctx,
		     LAST_CTX_TO_EP_NUM(le32_to_cpu(slot_ctx->dev_info)));

	/* Free any rings that were dropped, but not changed. */
	for (i = 1; i < 31; ++i) {
		if ((le32_to_cpu(ctrl_ctx->drop_flags) & (1 << (i + 1))) &&
		    !(le32_to_cpu(ctrl_ctx->add_flags) & (1 << (i + 1))))
			xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
	}
	xhci_zero_in_ctx(xhci, virt_dev);
	/*
	 * Install any rings for completely new endpoints or changed endpoints,
	 * and free or cache any old rings from changed endpoints.
	 */
	for (i = 1; i < 31; ++i) {
		if (!virt_dev->eps[i].new_ring)
			continue;
		/* Only cache or free the old ring if it exists.
		 * It may not if this is the first add of an endpoint.
		 */
		if (virt_dev->eps[i].ring) {
			xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
		}
		virt_dev->eps[i].ring = virt_dev->eps[i].new_ring;
		virt_dev->eps[i].new_ring = NULL;
	}

	return ret;
}

void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
	struct xhci_hcd *xhci;
	struct xhci_virt_device	*virt_dev;
	int i, ret;

	ret = xhci_check_args(hcd, udev, NULL, 0, true, __func__);
	if (ret <= 0)
		return;
	xhci = hcd_to_xhci(hcd);

	xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
	virt_dev = xhci->devs[udev->slot_id];
	/* Free any rings allocated for added endpoints */
	for (i = 0; i < 31; ++i) {
		if (virt_dev->eps[i].new_ring) {
			xhci_ring_free(xhci, virt_dev->eps[i].new_ring);
			virt_dev->eps[i].new_ring = NULL;
		}
	}
	xhci_zero_in_ctx(xhci, virt_dev);
}

static void xhci_setup_input_ctx_for_config_ep(struct xhci_hcd *xhci,
		struct xhci_container_ctx *in_ctx,
		struct xhci_container_ctx *out_ctx,
		u32 add_flags, u32 drop_flags)
{
	struct xhci_input_control_ctx *ctrl_ctx;
	ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
	ctrl_ctx->add_flags = cpu_to_le32(add_flags);
	ctrl_ctx->drop_flags = cpu_to_le32(drop_flags);
	xhci_slot_copy(xhci, in_ctx, out_ctx);
	ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);

	xhci_dbg(xhci, "Input Context:\n");
	xhci_dbg_ctx(xhci, in_ctx, xhci_last_valid_endpoint(add_flags));
}

static void xhci_setup_input_ctx_for_quirk(struct xhci_hcd *xhci,
		unsigned int slot_id, unsigned int ep_index,
		struct xhci_dequeue_state *deq_state)
{
	struct xhci_container_ctx *in_ctx;
	struct xhci_ep_ctx *ep_ctx;
	u32 added_ctxs;
	dma_addr_t addr;

	xhci_endpoint_copy(xhci, xhci->devs[slot_id]->in_ctx,
			xhci->devs[slot_id]->out_ctx, ep_index);
	in_ctx = xhci->devs[slot_id]->in_ctx;
	ep_ctx = xhci_get_ep_ctx(xhci, in_ctx, ep_index);
	addr = xhci_trb_virt_to_dma(deq_state->new_deq_seg,
			deq_state->new_deq_ptr);
	if (addr == 0) {
		xhci_warn(xhci, "WARN Cannot submit config ep after "
				"reset ep command\n");
		xhci_warn(xhci, "WARN deq seg = %p, deq ptr = %p\n",
				deq_state->new_deq_seg,
				deq_state->new_deq_ptr);
		return;
	}
	ep_ctx->deq = cpu_to_le64(addr | deq_state->new_cycle_state);

	added_ctxs = xhci_get_endpoint_flag_from_index(ep_index);
	xhci_setup_input_ctx_for_config_ep(xhci, xhci->devs[slot_id]->in_ctx,
			xhci->devs[slot_id]->out_ctx, added_ctxs, added_ctxs);
}

void xhci_cleanup_stalled_ring(struct xhci_hcd *xhci,
		struct usb_device *udev, unsigned int ep_index)
{
	struct xhci_dequeue_state deq_state;
	struct xhci_virt_ep *ep;

	xhci_dbg(xhci, "Cleaning up stalled endpoint ring\n");
	ep = &xhci->devs[udev->slot_id]->eps[ep_index];
	/* We need to move the HW's dequeue pointer past this TD,
	 * or it will attempt to resend it on the next doorbell ring.
	 */
	xhci_find_new_dequeue_state(xhci, udev->slot_id,
			ep_index, ep->stopped_stream, ep->stopped_td,
			&deq_state);

	/* HW with the reset endpoint quirk will use the saved dequeue state to
	 * issue a configure endpoint command later.
	 */
	if (!(xhci->quirks & XHCI_RESET_EP_QUIRK)) {
		xhci_dbg(xhci, "Queueing new dequeue state\n");
		xhci_queue_new_dequeue_state(xhci, udev->slot_id,
				ep_index, ep->stopped_stream, &deq_state);
	} else {
		/* Better hope no one uses the input context between now and the
		 * reset endpoint completion!
		 * XXX: No idea how this hardware will react when stream rings
		 * are enabled.
		 */
		xhci_dbg(xhci, "Setting up input context for "
				"configure endpoint command\n");
		xhci_setup_input_ctx_for_quirk(xhci, udev->slot_id,
				ep_index, &deq_state);
	}
}

/* Deal with stalled endpoints.  The core should have sent the control message
 * to clear the halt condition.  However, we need to make the xHCI hardware
 * reset its sequence number, since a device will expect a sequence number of
 * zero after the halt condition is cleared.
 * Context: in_interrupt
 */
void xhci_endpoint_reset(struct usb_hcd *hcd,
		struct usb_host_endpoint *ep)
{
	struct xhci_hcd *xhci;
	struct usb_device *udev;
	unsigned int ep_index;
	unsigned long flags;
	int ret;
	struct xhci_virt_ep *virt_ep;

	xhci = hcd_to_xhci(hcd);
	udev = (struct usb_device *) ep->hcpriv;
	/* Called with a root hub endpoint (or an endpoint that wasn't added
	 * with xhci_add_endpoint()
	 */
	if (!ep->hcpriv)
		return;
	ep_index = xhci_get_endpoint_index(&ep->desc);
	virt_ep = &xhci->devs[udev->slot_id]->eps[ep_index];
	if (!virt_ep->stopped_td) {
		xhci_dbg(xhci, "Endpoint 0x%x not halted, refusing to reset.\n",
				ep->desc.bEndpointAddress);
		return;
	}
	if (usb_endpoint_xfer_control(&ep->desc)) {
		xhci_dbg(xhci, "Control endpoint stall already handled.\n");
		return;
	}

	xhci_dbg(xhci, "Queueing reset endpoint command\n");
	spin_lock_irqsave(&xhci->lock, flags);
	ret = xhci_queue_reset_ep(xhci, udev->slot_id, ep_index);
	/*
	 * Can't change the ring dequeue pointer until it's transitioned to the
	 * stopped state, which is only upon a successful reset endpoint
	 * command.  Better hope that last command worked!
	 */
	if (!ret) {
		xhci_cleanup_stalled_ring(xhci, udev, ep_index);
		kfree(virt_ep->stopped_td);
		xhci_ring_cmd_db(xhci);
	}
	virt_ep->stopped_td = NULL;
	virt_ep->stopped_trb = NULL;
	virt_ep->stopped_stream = 0;
	spin_unlock_irqrestore(&xhci->lock, flags);

	if (ret)
		xhci_warn(xhci, "FIXME allocate a new ring segment\n");
}

static int xhci_check_streams_endpoint(struct xhci_hcd *xhci,
		struct usb_device *udev, struct usb_host_endpoint *ep,
		unsigned int slot_id)
{
	int ret;
	unsigned int ep_index;
	unsigned int ep_state;

	if (!ep)
		return -EINVAL;
	ret = xhci_check_args(xhci_to_hcd(xhci), udev, ep, 1, true, __func__);
	if (ret <= 0)
		return -EINVAL;
	if (ep->ss_ep_comp.bmAttributes == 0) {
		xhci_warn(xhci, "WARN: SuperSpeed Endpoint Companion"
				" descriptor for ep 0x%x does not support streams\n",
				ep->desc.bEndpointAddress);
		return -EINVAL;
	}

	ep_index = xhci_get_endpoint_index(&ep->desc);
	ep_state = xhci->devs[slot_id]->eps[ep_index].ep_state;
	if (ep_state & EP_HAS_STREAMS ||
			ep_state & EP_GETTING_STREAMS) {
		xhci_warn(xhci, "WARN: SuperSpeed bulk endpoint 0x%x "
				"already has streams set up.\n",
				ep->desc.bEndpointAddress);
		xhci_warn(xhci, "Send email to xHCI maintainer and ask for "
				"dynamic stream context array reallocation.\n");
		return -EINVAL;
	}
	if (!list_empty(&xhci->devs[slot_id]->eps[ep_index].ring->td_list)) {
		xhci_warn(xhci, "Cannot setup streams for SuperSpeed bulk "
				"endpoint 0x%x; URBs are pending.\n",
				ep->desc.bEndpointAddress);
		return -EINVAL;
	}
	return 0;
}

static void xhci_calculate_streams_entries(struct xhci_hcd *xhci,
		unsigned int *num_streams, unsigned int *num_stream_ctxs)
{
	unsigned int max_streams;

	/* The stream context array size must be a power of two */
	*num_stream_ctxs = roundup_pow_of_two(*num_streams);
	/*
	 * Find out how many primary stream array entries the host controller
	 * supports.  Later we may use secondary stream arrays (similar to 2nd
	 * level page entries), but that's an optional feature for xHCI host
	 * controllers. xHCs must support at least 4 stream IDs.
	 */
	max_streams = HCC_MAX_PSA(xhci->hcc_params);
	if (*num_stream_ctxs > max_streams) {
		xhci_dbg(xhci, "xHCI HW only supports %u stream ctx entries.\n",
				max_streams);
		*num_stream_ctxs = max_streams;
		*num_streams = max_streams;
	}
}

/* Returns an error code if one of the endpoint already has streams.
 * This does not change any data structures, it only checks and gathers
 * information.
 */
static int xhci_calculate_streams_and_bitmask(struct xhci_hcd *xhci,
		struct usb_device *udev,
		struct usb_host_endpoint **eps, unsigned int num_eps,
		unsigned int *num_streams, u32 *changed_ep_bitmask)
{
	unsigned int max_streams;
	unsigned int endpoint_flag;
	int i;
	int ret;

	for (i = 0; i < num_eps; i++) {
		ret = xhci_check_streams_endpoint(xhci, udev,
				eps[i], udev->slot_id);
		if (ret < 0)
			return ret;

		max_streams = USB_SS_MAX_STREAMS(
				eps[i]->ss_ep_comp.bmAttributes);
		if (max_streams < (*num_streams - 1)) {
			xhci_dbg(xhci, "Ep 0x%x only supports %u stream IDs.\n",
					eps[i]->desc.bEndpointAddress,
					max_streams);
			*num_streams = max_streams+1;
		}

		endpoint_flag = xhci_get_endpoint_flag(&eps[i]->desc);
		if (*changed_ep_bitmask & endpoint_flag)
			return -EINVAL;
		*changed_ep_bitmask |= endpoint_flag;
	}
	return 0;
}

static u32 xhci_calculate_no_streams_bitmask(struct xhci_hcd *xhci,
		struct usb_device *udev,
		struct usb_host_endpoint **eps, unsigned int num_eps)
{
	u32 changed_ep_bitmask = 0;
	unsigned int slot_id;
	unsigned int ep_index;
	unsigned int ep_state;
	int i;

	slot_id = udev->slot_id;
	if (!xhci->devs[slot_id])
		return 0;

	for (i = 0; i < num_eps; i++) {
		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		ep_state = xhci->devs[slot_id]->eps[ep_index].ep_state;
		/* Are streams already being freed for the endpoint? */
		if (ep_state & EP_GETTING_NO_STREAMS) {
			xhci_warn(xhci, "WARN Can't disable streams for "
					"endpoint 0x%x\n, "
					"streams are being disabled already.",
					eps[i]->desc.bEndpointAddress);
			return 0;
		}
		/* Are there actually any streams to free? */
		if (!(ep_state & EP_HAS_STREAMS) &&
				!(ep_state & EP_GETTING_STREAMS)) {
			xhci_warn(xhci, "WARN Can't disable streams for "
					"endpoint 0x%x\n, "
					"streams are already disabled!",
					eps[i]->desc.bEndpointAddress);
			xhci_warn(xhci, "WARN xhci_free_streams() called "
					"with non-streams endpoint\n");
			return 0;
		}
		changed_ep_bitmask |= xhci_get_endpoint_flag(&eps[i]->desc);
	}
	return changed_ep_bitmask;
}

/*
 * The USB device drivers use this function (though the HCD interface in USB
 * core) to prepare a set of bulk endpoints to use streams.  Streams are used to
 * coordinate mass storage command queueing across multiple endpoints (basically
 * a stream ID == a task ID).
 *
 * Setting up streams involves allocating the same size stream context array
 * for each endpoint and issuing a configure endpoint command for all endpoints.
 *
 * Don't allow the call to succeed if one endpoint only supports one stream
 * (which means it doesn't support streams at all).
 *
 * Drivers may get less stream IDs than they asked for, if the host controller
 * hardware or endpoints claim they can't support the number of requested
 * stream IDs.
 */
int xhci_alloc_streams(struct usb_hcd *hcd, struct usb_device *udev,
		struct usb_host_endpoint **eps, unsigned int num_eps,
		unsigned int num_streams, gfp_t mem_flags)
{
	int i, ret;
	struct xhci_hcd *xhci;
	struct xhci_virt_device *vdev;
	struct xhci_command *config_cmd;
	unsigned int ep_index;
	unsigned int num_stream_ctxs;
	unsigned long flags;
	u32 changed_ep_bitmask = 0;

	if (!eps)
		return -EINVAL;

	/* Add one to the number of streams requested to account for
	 * stream 0 that is reserved for xHCI usage.
	 */
	num_streams += 1;
	xhci = hcd_to_xhci(hcd);
	xhci_dbg(xhci, "Driver wants %u stream IDs (including stream 0).\n",
			num_streams);

	config_cmd = xhci_alloc_command(xhci, true, true, mem_flags);
	if (!config_cmd) {
		xhci_dbg(xhci, "Could not allocate xHCI command structure.\n");
		return -ENOMEM;
	}

	/* Check to make sure all endpoints are not already configured for
	 * streams.  While we're at it, find the maximum number of streams that
	 * all the endpoints will support and check for duplicate endpoints.
	 */
	spin_lock_irqsave(&xhci->lock, flags);
	ret = xhci_calculate_streams_and_bitmask(xhci, udev, eps,
			num_eps, &num_streams, &changed_ep_bitmask);
	if (ret < 0) {
		xhci_free_command(xhci, config_cmd);
		spin_unlock_irqrestore(&xhci->lock, flags);
		return ret;
	}
	if (num_streams <= 1) {
		xhci_warn(xhci, "WARN: endpoints can't handle "
				"more than one stream.\n");
		xhci_free_command(xhci, config_cmd);
		spin_unlock_irqrestore(&xhci->lock, flags);
		return -EINVAL;
	}
	vdev = xhci->devs[udev->slot_id];
	/* Mark each endpoint as being in transition, so
	 * xhci_urb_enqueue() will reject all URBs.
	 */
	for (i = 0; i < num_eps; i++) {
		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		vdev->eps[ep_index].ep_state |= EP_GETTING_STREAMS;
	}
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* Setup internal data structures and allocate HW data structures for
	 * streams (but don't install the HW structures in the input context
	 * until we're sure all memory allocation succeeded).
	 */
	xhci_calculate_streams_entries(xhci, &num_streams, &num_stream_ctxs);
	xhci_dbg(xhci, "Need %u stream ctx entries for %u stream IDs.\n",
			num_stream_ctxs, num_streams);

	for (i = 0; i < num_eps; i++) {
		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		vdev->eps[ep_index].stream_info = xhci_alloc_stream_info(xhci,
				num_stream_ctxs,
				num_streams, mem_flags);
		if (!vdev->eps[ep_index].stream_info)
			goto cleanup;
		/* Set maxPstreams in endpoint context and update deq ptr to
		 * point to stream context array. FIXME
		 */
	}

	/* Set up the input context for a configure endpoint command. */
	for (i = 0; i < num_eps; i++) {
		struct xhci_ep_ctx *ep_ctx;

		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		ep_ctx = xhci_get_ep_ctx(xhci, config_cmd->in_ctx, ep_index);

		xhci_endpoint_copy(xhci, config_cmd->in_ctx,
				vdev->out_ctx, ep_index);
		xhci_setup_streams_ep_input_ctx(xhci, ep_ctx,
				vdev->eps[ep_index].stream_info);
	}
	/* Tell the HW to drop its old copy of the endpoint context info
	 * and add the updated copy from the input context.
	 */
	xhci_setup_input_ctx_for_config_ep(xhci, config_cmd->in_ctx,
			vdev->out_ctx, changed_ep_bitmask, changed_ep_bitmask);

	/* Issue and wait for the configure endpoint command */
	ret = xhci_configure_endpoint(xhci, udev, config_cmd,
			false, false);

	/* xHC rejected the configure endpoint command for some reason, so we
	 * leave the old ring intact and free our internal streams data
	 * structure.
	 */
	if (ret < 0)
		goto cleanup;

	spin_lock_irqsave(&xhci->lock, flags);
	for (i = 0; i < num_eps; i++) {
		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		vdev->eps[ep_index].ep_state &= ~EP_GETTING_STREAMS;
		xhci_dbg(xhci, "Slot %u ep ctx %u now has streams.\n",
			 udev->slot_id, ep_index);
		vdev->eps[ep_index].ep_state |= EP_HAS_STREAMS;
	}
	xhci_free_command(xhci, config_cmd);
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* Subtract 1 for stream 0, which drivers can't use */
	return num_streams - 1;

cleanup:
	/* If it didn't work, free the streams! */
	for (i = 0; i < num_eps; i++) {
		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		xhci_free_stream_info(xhci, vdev->eps[ep_index].stream_info);
		vdev->eps[ep_index].stream_info = NULL;
		/* FIXME Unset maxPstreams in endpoint context and
		 * update deq ptr to point to normal string ring.
		 */
		vdev->eps[ep_index].ep_state &= ~EP_GETTING_STREAMS;
		vdev->eps[ep_index].ep_state &= ~EP_HAS_STREAMS;
		xhci_endpoint_zero(xhci, vdev, eps[i]);
	}
	xhci_free_command(xhci, config_cmd);
	return -ENOMEM;
}

/* Transition the endpoint from using streams to being a "normal" endpoint
 * without streams.
 *
 * Modify the endpoint context state, submit a configure endpoint command,
 * and free all endpoint rings for streams if that completes successfully.
 */
int xhci_free_streams(struct usb_hcd *hcd, struct usb_device *udev,
		struct usb_host_endpoint **eps, unsigned int num_eps,
		gfp_t mem_flags)
{
	int i, ret;
	struct xhci_hcd *xhci;
	struct xhci_virt_device *vdev;
	struct xhci_command *command;
	unsigned int ep_index;
	unsigned long flags;
	u32 changed_ep_bitmask;

	xhci = hcd_to_xhci(hcd);
	vdev = xhci->devs[udev->slot_id];

	/* Set up a configure endpoint command to remove the streams rings */
	spin_lock_irqsave(&xhci->lock, flags);
	changed_ep_bitmask = xhci_calculate_no_streams_bitmask(xhci,
			udev, eps, num_eps);
	if (changed_ep_bitmask == 0) {
		spin_unlock_irqrestore(&xhci->lock, flags);
		return -EINVAL;
	}

	/* Use the xhci_command structure from the first endpoint.  We may have
	 * allocated too many, but the driver may call xhci_free_streams() for
	 * each endpoint it grouped into one call to xhci_alloc_streams().
	 */
	ep_index = xhci_get_endpoint_index(&eps[0]->desc);
	command = vdev->eps[ep_index].stream_info->free_streams_command;
	for (i = 0; i < num_eps; i++) {
		struct xhci_ep_ctx *ep_ctx;

		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		ep_ctx = xhci_get_ep_ctx(xhci, command->in_ctx, ep_index);
		xhci->devs[udev->slot_id]->eps[ep_index].ep_state |=
			EP_GETTING_NO_STREAMS;

		xhci_endpoint_copy(xhci, command->in_ctx,
				vdev->out_ctx, ep_index);
		xhci_setup_no_streams_ep_input_ctx(xhci, ep_ctx,
				&vdev->eps[ep_index]);
	}
	xhci_setup_input_ctx_for_config_ep(xhci, command->in_ctx,
			vdev->out_ctx, changed_ep_bitmask, changed_ep_bitmask);
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* Issue and wait for the configure endpoint command,
	 * which must succeed.
	 */
	ret = xhci_configure_endpoint(xhci, udev, command,
			false, true);

	/* xHC rejected the configure endpoint command for some reason, so we
	 * leave the streams rings intact.
	 */
	if (ret < 0)
		return ret;

	spin_lock_irqsave(&xhci->lock, flags);
	for (i = 0; i < num_eps; i++) {
		ep_index = xhci_get_endpoint_index(&eps[i]->desc);
		xhci_free_stream_info(xhci, vdev->eps[ep_index].stream_info);
		vdev->eps[ep_index].stream_info = NULL;
		/* FIXME Unset maxPstreams in endpoint context and
		 * update deq ptr to point to normal string ring.
		 */
		vdev->eps[ep_index].ep_state &= ~EP_GETTING_NO_STREAMS;
		vdev->eps[ep_index].ep_state &= ~EP_HAS_STREAMS;
	}
	spin_unlock_irqrestore(&xhci->lock, flags);

	return 0;
}

/*
 * Deletes endpoint resources for endpoints that were active before a Reset
 * Device command, or a Disable Slot command.  The Reset Device command leaves
 * the control endpoint intact, whereas the Disable Slot command deletes it.
 *
 * Must be called with xhci->lock held.
 */
void xhci_free_device_endpoint_resources(struct xhci_hcd *xhci,
	struct xhci_virt_device *virt_dev, bool drop_control_ep)
{
	int i;
	unsigned int num_dropped_eps = 0;
	unsigned int drop_flags = 0;

	for (i = (drop_control_ep ? 0 : 1); i < 31; i++) {
		if (virt_dev->eps[i].ring) {
			drop_flags |= 1 << i;
			num_dropped_eps++;
		}
	}
	xhci->num_active_eps -= num_dropped_eps;
	if (num_dropped_eps)
		xhci_dbg(xhci, "Dropped %u ep ctxs, flags = 0x%x, "
				"%u now active.\n",
				num_dropped_eps, drop_flags,
				xhci->num_active_eps);
}

/*
 * This submits a Reset Device Command, which will set the device state to 0,
 * set the device address to 0, and disable all the endpoints except the default
 * control endpoint.  The USB core should come back and call
 * xhci_address_device(), and then re-set up the configuration.  If this is
 * called because of a usb_reset_and_verify_device(), then the old alternate
 * settings will be re-installed through the normal bandwidth allocation
 * functions.
 *
 * Wait for the Reset Device command to finish.  Remove all structures
 * associated with the endpoints that were disabled.  Clear the input device
 * structure?  Cache the rings?  Reset the control endpoint 0 max packet size?
 *
 * If the virt_dev to be reset does not exist or does not match the udev,
 * it means the device is lost, possibly due to the xHC restore error and
 * re-initialization during S3/S4. In this case, call xhci_alloc_dev() to
 * re-allocate the device.
 */
int xhci_discover_or_reset_device(struct usb_hcd *hcd, struct usb_device *udev)
{
	int ret, i;
	unsigned long flags;
	struct xhci_hcd *xhci;
	unsigned int slot_id;
	struct xhci_virt_device *virt_dev;
	struct xhci_command *reset_device_cmd;
	int timeleft;
	int last_freed_endpoint;

	ret = xhci_check_args(hcd, udev, NULL, 0, false, __func__);
	if (ret <= 0)
		return ret;
	xhci = hcd_to_xhci(hcd);
	slot_id = udev->slot_id;
	virt_dev = xhci->devs[slot_id];
	if (!virt_dev) {
		xhci_dbg(xhci, "The device to be reset with slot ID %u does "
				"not exist. Re-allocate the device\n", slot_id);
		ret = xhci_alloc_dev(hcd, udev);
		if (ret == 1)
			return 0;
		else
			return -EINVAL;
	}

	if (virt_dev->udev != udev) {
		/* If the virt_dev and the udev does not match, this virt_dev
		 * may belong to another udev.
		 * Re-allocate the device.
		 */
		xhci_dbg(xhci, "The device to be reset with slot ID %u does "
				"not match the udev. Re-allocate the device\n",
				slot_id);
		ret = xhci_alloc_dev(hcd, udev);
		if (ret == 1)
			return 0;
		else
			return -EINVAL;
	}

	xhci_dbg(xhci, "Resetting device with slot ID %u\n", slot_id);
	/* Allocate the command structure that holds the struct completion.
	 * Assume we're in process context, since the normal device reset
	 * process has to wait for the device anyway.  Storage devices are
	 * reset as part of error handling, so use GFP_NOIO instead of
	 * GFP_KERNEL.
	 */
	reset_device_cmd = xhci_alloc_command(xhci, false, true, GFP_NOIO);
	if (!reset_device_cmd) {
		xhci_dbg(xhci, "Couldn't allocate command structure.\n");
		return -ENOMEM;
	}

	/* Attempt to submit the Reset Device command to the command ring */
	spin_lock_irqsave(&xhci->lock, flags);
	reset_device_cmd->command_trb = xhci->cmd_ring->enqueue;

	/* Enqueue pointer can be left pointing to the link TRB,
	 * we must handle that
	 */
	if ((le32_to_cpu(reset_device_cmd->command_trb->link.control)
	     & TRB_TYPE_BITMASK) == TRB_TYPE(TRB_LINK))
		reset_device_cmd->command_trb =
			xhci->cmd_ring->enq_seg->next->trbs;

	list_add_tail(&reset_device_cmd->cmd_list, &virt_dev->cmd_list);
	ret = xhci_queue_reset_device(xhci, slot_id);
	if (ret) {
		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
		list_del(&reset_device_cmd->cmd_list);
		spin_unlock_irqrestore(&xhci->lock, flags);
		goto command_cleanup;
	}
	xhci_ring_cmd_db(xhci);
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* Wait for the Reset Device command to finish */
	timeleft = wait_for_completion_interruptible_timeout(
			reset_device_cmd->completion,
			USB_CTRL_SET_TIMEOUT);
	if (timeleft <= 0) {
		xhci_warn(xhci, "%s while waiting for reset device command\n",
				timeleft == 0 ? "Timeout" : "Signal");
		spin_lock_irqsave(&xhci->lock, flags);
		/* The timeout might have raced with the event ring handler, so
		 * only delete from the list if the item isn't poisoned.
		 */
		if (reset_device_cmd->cmd_list.next != LIST_POISON1)
			list_del(&reset_device_cmd->cmd_list);
		spin_unlock_irqrestore(&xhci->lock, flags);
		ret = -ETIME;
		goto command_cleanup;
	}

	/* The Reset Device command can't fail, according to the 0.95/0.96 spec,
	 * unless we tried to reset a slot ID that wasn't enabled,
	 * or the device wasn't in the addressed or configured state.
	 */
	ret = reset_device_cmd->status;
	switch (ret) {
	case COMP_EBADSLT: /* 0.95 completion code for bad slot ID */
	case COMP_CTX_STATE: /* 0.96 completion code for same thing */
		xhci_info(xhci, "Can't reset device (slot ID %u) in %s state\n",
				slot_id,
				xhci_get_slot_state(xhci, virt_dev->out_ctx));
		xhci_info(xhci, "Not freeing device rings.\n");
		/* Don't treat this as an error.  May change my mind later. */
		ret = 0;
		goto command_cleanup;
	case COMP_SUCCESS:
		xhci_dbg(xhci, "Successful reset device command.\n");
		break;
	default:
		if (xhci_is_vendor_info_code(xhci, ret))
			break;
		xhci_warn(xhci, "Unknown completion code %u for "
				"reset device command.\n", ret);
		ret = -EINVAL;
		goto command_cleanup;
	}

	/* Free up host controller endpoint resources */
	if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
		spin_lock_irqsave(&xhci->lock, flags);
		/* Don't delete the default control endpoint resources */
		xhci_free_device_endpoint_resources(xhci, virt_dev, false);
		spin_unlock_irqrestore(&xhci->lock, flags);
	}

	/* Everything but endpoint 0 is disabled, so free or cache the rings. */
	last_freed_endpoint = 1;
	for (i = 1; i < 31; ++i) {
		struct xhci_virt_ep *ep = &virt_dev->eps[i];

		if (ep->ep_state & EP_HAS_STREAMS) {
			xhci_free_stream_info(xhci, ep->stream_info);
			ep->stream_info = NULL;
			ep->ep_state &= ~EP_HAS_STREAMS;
		}

		if (ep->ring) {
			xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
			last_freed_endpoint = i;
		}
	}
	xhci_dbg(xhci, "Output context after successful reset device cmd:\n");
	xhci_dbg_ctx(xhci, virt_dev->out_ctx, last_freed_endpoint);
	ret = 0;

command_cleanup:
	xhci_free_command(xhci, reset_device_cmd);
	return ret;
}

/*
 * At this point, the struct usb_device is about to go away, the device has
 * disconnected, and all traffic has been stopped and the endpoints have been
 * disabled.  Free any HC data structures associated with that device.
 */
void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	struct xhci_virt_device *virt_dev;
	unsigned long flags;
	u32 state;
	int i, ret;

	ret = xhci_check_args(hcd, udev, NULL, 0, true, __func__);
	if (ret <= 0)
		return;

	virt_dev = xhci->devs[udev->slot_id];

	/* Stop any wayward timer functions (which may grab the lock) */
	for (i = 0; i < 31; ++i) {
		virt_dev->eps[i].ep_state &= ~EP_HALT_PENDING;
		del_timer_sync(&virt_dev->eps[i].stop_cmd_timer);
	}

	spin_lock_irqsave(&xhci->lock, flags);
	/* Don't disable the slot if the host controller is dead. */
	state = xhci_readl(xhci, &xhci->op_regs->status);
	if (state == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING)) {
		xhci_free_virt_device(xhci, udev->slot_id);
		spin_unlock_irqrestore(&xhci->lock, flags);
		return;
	}

	if (xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id)) {
		spin_unlock_irqrestore(&xhci->lock, flags);
		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
		return;
	}
	xhci_ring_cmd_db(xhci);
	spin_unlock_irqrestore(&xhci->lock, flags);
	/*
	 * Event command completion handler will free any data structures
	 * associated with the slot.  XXX Can free sleep?
	 */
}

/*
 * Checks if we have enough host controller resources for the default control
 * endpoint.
 *
 * Must be called with xhci->lock held.
 */
static int xhci_reserve_host_control_ep_resources(struct xhci_hcd *xhci)
{
	if (xhci->num_active_eps + 1 > xhci->limit_active_eps) {
		xhci_dbg(xhci, "Not enough ep ctxs: "
				"%u active, need to add 1, limit is %u.\n",
				xhci->num_active_eps, xhci->limit_active_eps);
		return -ENOMEM;
	}
	xhci->num_active_eps += 1;
	xhci_dbg(xhci, "Adding 1 ep ctx, %u now active.\n",
			xhci->num_active_eps);
	return 0;
}


/*
 * Returns 0 if the xHC ran out of device slots, the Enable Slot command
 * timed out, or allocating memory failed.  Returns 1 on success.
 */
int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	unsigned long flags;
	int timeleft;
	int ret;

	spin_lock_irqsave(&xhci->lock, flags);
	ret = xhci_queue_slot_control(xhci, TRB_ENABLE_SLOT, 0);
	if (ret) {
		spin_unlock_irqrestore(&xhci->lock, flags);
		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
		return 0;
	}
	xhci_ring_cmd_db(xhci);
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* XXX: how much time for xHC slot assignment? */
	timeleft = wait_for_completion_interruptible_timeout(&xhci->addr_dev,
			USB_CTRL_SET_TIMEOUT);
	if (timeleft <= 0) {
		xhci_warn(xhci, "%s while waiting for a slot\n",
				timeleft == 0 ? "Timeout" : "Signal");
		/* FIXME cancel the enable slot request */
		return 0;
	}

	if (!xhci->slot_id) {
		xhci_err(xhci, "Error while assigning device slot ID\n");
		return 0;
	}

	if ((xhci->quirks & XHCI_EP_LIMIT_QUIRK)) {
		spin_lock_irqsave(&xhci->lock, flags);
		ret = xhci_reserve_host_control_ep_resources(xhci);
		if (ret) {
			spin_unlock_irqrestore(&xhci->lock, flags);
			xhci_warn(xhci, "Not enough host resources, "
					"active endpoint contexts = %u\n",
					xhci->num_active_eps);
			goto disable_slot;
		}
		spin_unlock_irqrestore(&xhci->lock, flags);
	}
	/* Use GFP_NOIO, since this function can be called from
	 * xhci_discover_or_reset_device(), which may be called as part of
	 * mass storage driver error handling.
	 */
	if (!xhci_alloc_virt_device(xhci, xhci->slot_id, udev, GFP_NOIO)) {
		xhci_warn(xhci, "Could not allocate xHCI USB device data structures\n");
		goto disable_slot;
	}
	udev->slot_id = xhci->slot_id;
	/* Is this a LS or FS device under a HS hub? */
	/* Hub or peripherial? */
	return 1;

disable_slot:
	/* Disable slot, if we can do it without mem alloc */
	spin_lock_irqsave(&xhci->lock, flags);
	if (!xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id))
		xhci_ring_cmd_db(xhci);
	spin_unlock_irqrestore(&xhci->lock, flags);
	return 0;
}

/*
 * Issue an Address Device command (which will issue a SetAddress request to
 * the device).
 * We should be protected by the usb_address0_mutex in khubd's hub_port_init, so
 * we should only issue and wait on one address command at the same time.
 *
 * We add one to the device address issued by the hardware because the USB core
 * uses address 1 for the root hubs (even though they're not really devices).
 */
int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
{
	unsigned long flags;
	int timeleft;
	struct xhci_virt_device *virt_dev;
	int ret = 0;
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	struct xhci_slot_ctx *slot_ctx;
	struct xhci_input_control_ctx *ctrl_ctx;
	u64 temp_64;

	if (!udev->slot_id) {
		xhci_dbg(xhci, "Bad Slot ID %d\n", udev->slot_id);
		return -EINVAL;
	}

	virt_dev = xhci->devs[udev->slot_id];

	if (WARN_ON(!virt_dev)) {
		/*
		 * In plug/unplug torture test with an NEC controller,
		 * a zero-dereference was observed once due to virt_dev = 0.
		 * Print useful debug rather than crash if it is observed again!
		 */
		xhci_warn(xhci, "Virt dev invalid for slot_id 0x%x!\n",
			udev->slot_id);
		return -EINVAL;
	}

	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
	/*
	 * If this is the first Set Address since device plug-in or
	 * virt_device realloaction after a resume with an xHCI power loss,
	 * then set up the slot context.
	 */
	if (!slot_ctx->dev_info)
		xhci_setup_addressable_virt_dev(xhci, udev);
	/* Otherwise, update the control endpoint ring enqueue pointer. */
	else
		xhci_copy_ep0_dequeue_into_input_ctx(xhci, udev);
	xhci_dbg(xhci, "Slot ID %d Input Context:\n", udev->slot_id);
	xhci_dbg_ctx(xhci, virt_dev->in_ctx, 2);

	spin_lock_irqsave(&xhci->lock, flags);
	ret = xhci_queue_address_device(xhci, virt_dev->in_ctx->dma,
					udev->slot_id);
	if (ret) {
		spin_unlock_irqrestore(&xhci->lock, flags);
		xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
		return ret;
	}
	xhci_ring_cmd_db(xhci);
	spin_unlock_irqrestore(&xhci->lock, flags);

	/* ctrl tx can take up to 5 sec; XXX: need more time for xHC? */
	timeleft = wait_for_completion_interruptible_timeout(&xhci->addr_dev,
			USB_CTRL_SET_TIMEOUT);
	/* FIXME: From section 4.3.4: "Software shall be responsible for timing
	 * the SetAddress() "recovery interval" required by USB and aborting the
	 * command on a timeout.
	 */
	if (timeleft <= 0) {
		xhci_warn(xhci, "%s while waiting for a slot\n",
				timeleft == 0 ? "Timeout" : "Signal");
		/* FIXME cancel the address device command */
		return -ETIME;
	}

	switch (virt_dev->cmd_status) {
	case COMP_CTX_STATE:
	case COMP_EBADSLT:
		xhci_err(xhci, "Setup ERROR: address device command for slot %d.\n",
				udev->slot_id);
		ret = -EINVAL;
		break;
	case COMP_TX_ERR:
		dev_warn(&udev->dev, "Device not responding to set address.\n");
		ret = -EPROTO;
		break;
	case COMP_SUCCESS:
		xhci_dbg(xhci, "Successful Address Device command\n");
		break;
	default:
		xhci_err(xhci, "ERROR: unexpected command completion "
				"code 0x%x.\n", virt_dev->cmd_status);
		xhci_dbg(xhci, "Slot ID %d Output Context:\n", udev->slot_id);
		xhci_dbg_ctx(xhci, virt_dev->out_ctx, 2);
		ret = -EINVAL;
		break;
	}
	if (ret) {
		return ret;
	}
	temp_64 = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
	xhci_dbg(xhci, "Op regs DCBAA ptr = %#016llx\n", temp_64);
	xhci_dbg(xhci, "Slot ID %d dcbaa entry @%p = %#016llx\n",
		 udev->slot_id,
		 &xhci->dcbaa->dev_context_ptrs[udev->slot_id],
		 (unsigned long long)
		 le64_to_cpu(xhci->dcbaa->dev_context_ptrs[udev->slot_id]));
	xhci_dbg(xhci, "Output Context DMA address = %#08llx\n",
			(unsigned long long)virt_dev->out_ctx->dma);
	xhci_dbg(xhci, "Slot ID %d Input Context:\n", udev->slot_id);
	xhci_dbg_ctx(xhci, virt_dev->in_ctx, 2);
	xhci_dbg(xhci, "Slot ID %d Output Context:\n", udev->slot_id);
	xhci_dbg_ctx(xhci, virt_dev->out_ctx, 2);
	/*
	 * USB core uses address 1 for the roothubs, so we add one to the
	 * address given back to us by the HC.
	 */
	slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
	/* Use kernel assigned address for devices; store xHC assigned
	 * address locally. */
	virt_dev->address = (le32_to_cpu(slot_ctx->dev_state) & DEV_ADDR_MASK)
		+ 1;
	/* Zero the input context control for later use */
	ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
	ctrl_ctx->add_flags = 0;
	ctrl_ctx->drop_flags = 0;

	xhci_dbg(xhci, "Internal device address = %d\n", virt_dev->address);

	return 0;
}

/* Once a hub descriptor is fetched for a device, we need to update the xHC's
 * internal data structures for the device.
 */
int xhci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev,
			struct usb_tt *tt, gfp_t mem_flags)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	struct xhci_virt_device *vdev;
	struct xhci_command *config_cmd;
	struct xhci_input_control_ctx *ctrl_ctx;
	struct xhci_slot_ctx *slot_ctx;
	unsigned long flags;
	unsigned think_time;
	int ret;

	/* Ignore root hubs */
	if (!hdev->parent)
		return 0;

	vdev = xhci->devs[hdev->slot_id];
	if (!vdev) {
		xhci_warn(xhci, "Cannot update hub desc for unknown device.\n");
		return -EINVAL;
	}
	config_cmd = xhci_alloc_command(xhci, true, true, mem_flags);
	if (!config_cmd) {
		xhci_dbg(xhci, "Could not allocate xHCI command structure.\n");
		return -ENOMEM;
	}

	spin_lock_irqsave(&xhci->lock, flags);
	xhci_slot_copy(xhci, config_cmd->in_ctx, vdev->out_ctx);
	ctrl_ctx = xhci_get_input_control_ctx(xhci, config_cmd->in_ctx);
	ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
	slot_ctx = xhci_get_slot_ctx(xhci, config_cmd->in_ctx);
	slot_ctx->dev_info |= cpu_to_le32(DEV_HUB);
	if (tt->multi)
		slot_ctx->dev_info |= cpu_to_le32(DEV_MTT);
	if (xhci->hci_version > 0x95) {
		xhci_dbg(xhci, "xHCI version %x needs hub "
				"TT think time and number of ports\n",
				(unsigned int) xhci->hci_version);
		slot_ctx->dev_info2 |= cpu_to_le32(XHCI_MAX_PORTS(hdev->maxchild));
		/* Set TT think time - convert from ns to FS bit times.
		 * 0 = 8 FS bit times, 1 = 16 FS bit times,
		 * 2 = 24 FS bit times, 3 = 32 FS bit times.
		 *
		 * xHCI 1.0: this field shall be 0 if the device is not a
		 * High-spped hub.
		 */
		think_time = tt->think_time;
		if (think_time != 0)
			think_time = (think_time / 666) - 1;
		if (xhci->hci_version < 0x100 || hdev->speed == USB_SPEED_HIGH)
			slot_ctx->tt_info |=
				cpu_to_le32(TT_THINK_TIME(think_time));
	} else {
		xhci_dbg(xhci, "xHCI version %x doesn't need hub "
				"TT think time or number of ports\n",
				(unsigned int) xhci->hci_version);
	}
	slot_ctx->dev_state = 0;
	spin_unlock_irqrestore(&xhci->lock, flags);

	xhci_dbg(xhci, "Set up %s for hub device.\n",
			(xhci->hci_version > 0x95) ?
			"configure endpoint" : "evaluate context");
	xhci_dbg(xhci, "Slot %u Input Context:\n", hdev->slot_id);
	xhci_dbg_ctx(xhci, config_cmd->in_ctx, 0);

	/* Issue and wait for the configure endpoint or
	 * evaluate context command.
	 */
	if (xhci->hci_version > 0x95)
		ret = xhci_configure_endpoint(xhci, hdev, config_cmd,
				false, false);
	else
		ret = xhci_configure_endpoint(xhci, hdev, config_cmd,
				true, false);

	xhci_dbg(xhci, "Slot %u Output Context:\n", hdev->slot_id);
	xhci_dbg_ctx(xhci, vdev->out_ctx, 0);

	xhci_free_command(xhci, config_cmd);
	return ret;
}

int xhci_get_frame(struct usb_hcd *hcd)
{
	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
	/* EHCI mods by the periodic size.  Why? */
	return xhci_readl(xhci, &xhci->run_regs->microframe_index) >> 3;
}

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_LICENSE("GPL");

static int __init xhci_hcd_init(void)
{
#ifdef CONFIG_PCI
	int retval = 0;

	retval = xhci_register_pci();

	if (retval < 0) {
		printk(KERN_DEBUG "Problem registering PCI driver.");
		return retval;
	}
#endif
	/*
	 * Check the compiler generated sizes of structures that must be laid
	 * out in specific ways for hardware access.
	 */
	BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8);
	BUILD_BUG_ON(sizeof(struct xhci_slot_ctx) != 8*32/8);
	BUILD_BUG_ON(sizeof(struct xhci_ep_ctx) != 8*32/8);
	/* xhci_device_control has eight fields, and also
	 * embeds one xhci_slot_ctx and 31 xhci_ep_ctx
	 */
	BUILD_BUG_ON(sizeof(struct xhci_stream_ctx) != 4*32/8);
	BUILD_BUG_ON(sizeof(union xhci_trb) != 4*32/8);
	BUILD_BUG_ON(sizeof(struct xhci_erst_entry) != 4*32/8);
	BUILD_BUG_ON(sizeof(struct xhci_cap_regs) != 7*32/8);
	BUILD_BUG_ON(sizeof(struct xhci_intr_reg) != 8*32/8);
	/* xhci_run_regs has eight fields and embeds 128 xhci_intr_regs */
	BUILD_BUG_ON(sizeof(struct xhci_run_regs) != (8+8*128)*32/8);
	BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8);
	return 0;
}
module_init(xhci_hcd_init);

static void __exit xhci_hcd_cleanup(void)
{
#ifdef CONFIG_PCI
	xhci_unregister_pci();
#endif
}
module_exit(xhci_hcd_cleanup);