[PATCH] USB UHCI: Add root-hub suspend/resume support

This patch implements (finally!) separate suspend and resume routines
for the root hub and the controller in the UHCI driver.  It also
changes the sequence used to reset the controller during initial
probing, so as to preserve the existing state during a Resume-From-Disk.
(This new sequence is what should be used in the PCI Quirks code for
early USB handoffs, incidentally.)  Lastly it adds a notion of the
controller being "inaccessible" while in a PCI low-power state, when
normal I/O operations shouldn't be allowed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/uhci-hcd.c

@@ -109,28 +109,113 @@ static inline void restart_timer(struct uhci_hcd *uhci)
 #include "uhci-debug.c"
 #include "uhci-q.c"
 
+/*
+ * Make sure the controller is completely inactive, unable to
+ * generate interrupts or do DMA.
+ */
 static void reset_hc(struct uhci_hcd *uhci)
 {
-	unsigned long io_addr = uhci->io_addr;
+	/* Turn off PIRQ enable and SMI enable.  (This also turns off the
+	 * BIOS's USB Legacy Support.)  Turn off all the R/WC bits too.
+	 */
+	pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
+			USBLEGSUP_RWC);
 
-	/* Turn off PIRQ, SMI, and all interrupts.  This also turns off
-	 * the BIOS's USB Legacy Support.
+	/* Reset the HC - this will force us to get a
+	 * new notification of any already connected
+	 * ports due to the virtual disconnect that it
+	 * implies.
 	 */
-	pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP, 0);
-	outw(0, uhci->io_addr + USBINTR);
+	outw(USBCMD_HCRESET, uhci->io_addr + USBCMD);
+	mb();
+	udelay(5);
+	if (inw(uhci->io_addr + USBCMD) & USBCMD_HCRESET)
+		dev_warn(uhci_dev(uhci), "HCRESET not completed yet!\n");
 
-	/* Global reset for 50ms */
-	outw(USBCMD_GRESET, io_addr + USBCMD);
-	msleep(50);
-	outw(0, io_addr + USBCMD);
+	/* Just to be safe, disable interrupt requests and
+	 * make sure the controller is stopped.
+	 */
+	outw(0, uhci->io_addr + USBINTR);
+	outw(0, uhci->io_addr + USBCMD);
 
-	/* Another 10ms delay */
-	msleep(10);
 	uhci->resume_detect = 0;
-	uhci->is_stopped = UHCI_IS_STOPPED;
+	uhci->port_c_suspend = uhci->suspended_ports =
+			uhci->resuming_ports = 0;
 	uhci->rh_state = UHCI_RH_RESET;
+	uhci->is_stopped = UHCI_IS_STOPPED;
+	uhci_to_hcd(uhci)->state = HC_STATE_HALT;
 }
 
+/*
+ * Initialize a controller that was newly discovered or has just been
+ * resumed.  In either case we can't be sure of its previous state.
+ */
+static void check_and_reset_hc(struct uhci_hcd *uhci)
+{
+	u16 legsup;
+	unsigned int cmd, intr;
+
+	/*
+	 * When restarting a suspended controller, we expect all the
+	 * settings to be the same as we left them:
+	 *
+	 *	PIRQ and SMI disabled, no R/WC bits set in USBLEGSUP;
+	 *	Controller is stopped and configured with EGSM set;
+	 *	No interrupts enabled except possibly Resume Detect.
+	 *
+	 * If any of these conditions are violated we do a complete reset.
+	 */
+	pci_read_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP, &legsup);
+	if (legsup & ~USBLEGSUP_RO) {
+		dev_dbg(uhci_dev(uhci), "%s: legsup = 0x%04x\n",
+				__FUNCTION__, legsup);
+		goto reset_needed;
+	}
+
+	cmd = inw(uhci->io_addr + USBCMD);
+	if ((cmd & USBCMD_RS) || !(cmd & USBCMD_CF) || !(cmd & USBCMD_EGSM)) {
+		dev_dbg(uhci_dev(uhci), "%s: cmd = 0x%04x\n",
+				__FUNCTION__, cmd);
+		goto reset_needed;
+	}
+
+	intr = inw(uhci->io_addr + USBINTR);
+	if (intr & (~USBINTR_RESUME)) {
+		dev_dbg(uhci_dev(uhci), "%s: intr = 0x%04x\n",
+				__FUNCTION__, intr);
+		goto reset_needed;
+	}
+	return;
+
+reset_needed:
+	dev_dbg(uhci_dev(uhci), "Performing full reset\n");
+	reset_hc(uhci);
+}
+
+/*
+ * Store the basic register settings needed by the controller.
+ */
+static void configure_hc(struct uhci_hcd *uhci)
+{
+	/* Set the frame length to the default: 1 ms exactly */
+	outb(USBSOF_DEFAULT, uhci->io_addr + USBSOF);
+
+	/* Store the frame list base address */
+	outl(uhci->fl->dma_handle, uhci->io_addr + USBFLBASEADD);
+
+	/* Set the current frame number */
+	outw(uhci->frame_number, uhci->io_addr + USBFRNUM);
+
+	/* Mark controller as running before we enable interrupts */
+	uhci_to_hcd(uhci)->state = HC_STATE_RUNNING;
+	mb();
+
+	/* Enable PIRQ */
+	pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
+			USBLEGSUP_DEFAULT);
+}
+
+
 static int resume_detect_interrupts_are_broken(struct uhci_hcd *uhci)
 {
 	int port;
@@ -163,7 +248,7 @@ static int resume_detect_interrupts_are_broken(struct uhci_hcd *uhci)
 	return 0;
 }
 
-static void suspend_hc(struct uhci_hcd *uhci, enum uhci_rh_state new_state)
+static void suspend_rh(struct uhci_hcd *uhci, enum uhci_rh_state new_state)
 __releases(uhci->lock)
 __acquires(uhci->lock)
 {
@@ -189,6 +274,7 @@ __acquires(uhci->lock)
 			0 : USBINTR_RESUME);
 	outw(int_enable, uhci->io_addr + USBINTR);
 	outw(USBCMD_EGSM | USBCMD_CF, uhci->io_addr + USBCMD);
+	mb();
 	udelay(5);
 
 	/* If we're auto-stopping then no devices have been attached
@@ -215,7 +301,22 @@ __acquires(uhci->lock)
 	uhci_scan_schedule(uhci, NULL);
 }
 
-static void wakeup_hc(struct uhci_hcd *uhci)
+static void start_rh(struct uhci_hcd *uhci)
+{
+	uhci->rh_state = UHCI_RH_RUNNING;
+	uhci->is_stopped = 0;
+	smp_wmb();
+
+	/* Mark it configured and running with a 64-byte max packet.
+	 * All interrupts are enabled, even though RESUME won't do anything.
+	 */
+	outw(USBCMD_RS | USBCMD_CF | USBCMD_MAXP, uhci->io_addr + USBCMD);
+	outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC | USBINTR_SP,
+			uhci->io_addr + USBINTR);
+	mb();
+}
+
+static void wakeup_rh(struct uhci_hcd *uhci)
 __releases(uhci->lock)
 __acquires(uhci->lock)
 {
@@ -237,62 +338,13 @@ __acquires(uhci->lock)
 
 		/* End Global Resume and wait for EOP to be sent */
 		outw(USBCMD_CF, uhci->io_addr + USBCMD);
+		mb();
 		udelay(4);
 		if (inw(uhci->io_addr + USBCMD) & USBCMD_FGR)
 			dev_warn(uhci_dev(uhci), "FGR not stopped yet!\n");
 	}
 
-	uhci->rh_state = UHCI_RH_RUNNING;
-	uhci->is_stopped = 0;
-	smp_wmb();
-
-	/* Mark it configured and running with a 64-byte max packet.
-	 * All interrupts are enabled, even though RD won't do anything.
-	 */
-	outw(USBCMD_RS | USBCMD_CF | USBCMD_MAXP, uhci->io_addr + USBCMD);
-	outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC | USBINTR_SP,
-			uhci->io_addr + USBINTR);
-}
-
-static int start_hc(struct uhci_hcd *uhci)
-{
-	unsigned long io_addr = uhci->io_addr;
-	int timeout = 10;
-
-	/*
-	 * Reset the HC - this will force us to get a
-	 * new notification of any already connected
-	 * ports due to the virtual disconnect that it
-	 * implies.
-	 */
-	outw(USBCMD_HCRESET, io_addr + USBCMD);
-	while (inw(io_addr + USBCMD) & USBCMD_HCRESET) {
-		if (--timeout < 0) {
-			dev_err(uhci_dev(uhci), "USBCMD_HCRESET timed out!\n");
-			return -ETIMEDOUT;
-		}
-		msleep(1);
-	}
-
-	/* Mark controller as running before we enable interrupts */
-	uhci_to_hcd(uhci)->state = HC_STATE_RUNNING;
-
-	/* Turn on PIRQ and all interrupts */
-	pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
-			USBLEGSUP_DEFAULT);
-	outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC | USBINTR_SP,
-		io_addr + USBINTR);
-
-	/* Start at frame 0 */
-	outw(0, io_addr + USBFRNUM);
-	outl(uhci->fl->dma_handle, io_addr + USBFLBASEADD);
-
-	/* Run and mark it configured with a 64-byte max packet */
-	uhci->rh_state = UHCI_RH_RUNNING;
-	outw(USBCMD_RS | USBCMD_CF | USBCMD_MAXP, io_addr + USBCMD);
-	uhci->is_stopped = 0;
-
-	return 0;
+	start_rh(uhci);
 }
 
 static void rh_state_transitions(struct uhci_hcd *uhci)
@@ -311,13 +363,13 @@ static void rh_state_transitions(struct uhci_hcd *uhci)
 		if (any_ports_active(uhci))
 			uhci->rh_state = UHCI_RH_RUNNING;
 		else if (time_after_eq(jiffies, uhci->auto_stop_time))
-			suspend_hc(uhci, UHCI_RH_AUTO_STOPPED);
+			suspend_rh(uhci, UHCI_RH_AUTO_STOPPED);
 		break;
 
 	    case UHCI_RH_AUTO_STOPPED:
 		/* wakeup if requested by a device */
 		if (uhci->resume_detect)
-			wakeup_hc(uhci);
+			wakeup_rh(uhci);
 		break;
 
 	    default:
@@ -336,7 +388,7 @@ static void stall_callback(unsigned long _uhci)
 
 	/* Poll for and perform state transitions */
 	rh_state_transitions(uhci);
-	if (unlikely(uhci->suspended_ports))
+	if (uhci->suspended_ports && !uhci->hc_inaccessible)
 		uhci_check_ports(uhci);
 
 	restart_timer(uhci);
@@ -346,7 +398,6 @@ static void stall_callback(unsigned long _uhci)
 static irqreturn_t uhci_irq(struct usb_hcd *hcd, struct pt_regs *regs)
 {
 	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
-	unsigned long io_addr = uhci->io_addr;
 	unsigned short status;
 
 	/*
@@ -354,10 +405,10 @@ static irqreturn_t uhci_irq(struct usb_hcd *hcd, struct pt_regs *regs)
 	 * interrupt cause.  Contrary to the UHCI specification, the
 	 * "HC Halted" status bit is persistent: it is RO, not R/WC.
 	 */
-	status = inw(io_addr + USBSTS);
+	status = inw(uhci->io_addr + USBSTS);
 	if (!(status & ~USBSTS_HCH))	/* shared interrupt, not mine */
 		return IRQ_NONE;
-	outw(status, io_addr + USBSTS);		/* Clear it */
+	outw(status, uhci->io_addr + USBSTS);		/* Clear it */
 
 	if (status & ~(USBSTS_USBINT | USBSTS_ERROR | USBSTS_RD)) {
 		if (status & USBSTS_HSE)
@@ -440,10 +491,10 @@ static int uhci_reset(struct usb_hcd *hcd)
 
 	uhci->io_addr = (unsigned long) hcd->rsrc_start;
 
-	/* Kick BIOS off this hardware and reset, so we won't get
-	 * interrupts from any previous setup.
+	/* Kick BIOS off this hardware and reset if the controller
+	 * isn't already safely quiescent.
 	 */
-	reset_hc(uhci);
+	check_and_reset_hc(uhci);
 	return 0;
 }
 
@@ -634,11 +685,12 @@ static int uhci_start(struct usb_hcd *hcd)
 
 	/*
 	 * Some architectures require a full mb() to enforce completion of
-	 * the memory writes above before the I/O transfers in start_hc().
+	 * the memory writes above before the I/O transfers in configure_hc().
 	 */
 	mb();
-	if ((retval = start_hc(uhci)) != 0)
-		goto err_alloc_skelqh;
+
+	configure_hc(uhci);
+	start_rh(uhci);
 
 	restart_timer(uhci);
 
@@ -656,9 +708,8 @@ static int uhci_start(struct usb_hcd *hcd)
  * error exits:
  */
 err_start_root_hub:
-	reset_hc(uhci);
-
 	del_timer_sync(&uhci->stall_timer);
+	reset_hc(uhci);
 
 err_alloc_skelqh:
 	for (i = 0; i < UHCI_NUM_SKELQH; i++)
@@ -699,9 +750,9 @@ static void uhci_stop(struct usb_hcd *hcd)
 	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 
 	del_timer_sync(&uhci->stall_timer);
-	reset_hc(uhci);
 
 	spin_lock_irq(&uhci->lock);
+	reset_hc(uhci);
 	uhci_scan_schedule(uhci, NULL);
 	spin_unlock_irq(&uhci->lock);
 	
@@ -709,12 +760,47 @@ static void uhci_stop(struct usb_hcd *hcd)
 }
 
 #ifdef CONFIG_PM
+static int uhci_rh_suspend(struct usb_hcd *hcd)
+{
+	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+	spin_lock_irq(&uhci->lock);
+	suspend_rh(uhci, UHCI_RH_SUSPENDED);
+	spin_unlock_irq(&uhci->lock);
+	return 0;
+}
+
+static int uhci_rh_resume(struct usb_hcd *hcd)
+{
+	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
+
+	spin_lock_irq(&uhci->lock);
+	wakeup_rh(uhci);
+	spin_unlock_irq(&uhci->lock);
+	return 0;
+}
+
 static int uhci_suspend(struct usb_hcd *hcd, pm_message_t message)
 {
 	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 
+	dev_dbg(uhci_dev(uhci), "%s\n", __FUNCTION__);
+
 	spin_lock_irq(&uhci->lock);
-	suspend_hc(uhci, UHCI_RH_SUSPENDED);
+
+#ifndef CONFIG_USB_SUSPEND
+	/* Otherwise this would never happen */
+	suspend_rh(uhci, UHCI_RH_SUSPENDED);
+#endif
+
+	/* All PCI host controllers are required to disable IRQ generation
+	 * at the source, so we must turn off PIRQ.
+	 */
+	pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP, 0);
+	uhci->hc_inaccessible = 1;
+
+	/* FIXME: Enable non-PME# remote wakeup? */
+
 	spin_unlock_irq(&uhci->lock);
 	return 0;
 }
@@ -723,28 +809,28 @@ static int uhci_resume(struct usb_hcd *hcd)
 {
 	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 
+	dev_dbg(uhci_dev(uhci), "%s\n", __FUNCTION__);
+
 	spin_lock_irq(&uhci->lock);
-	if (uhci->rh_state == UHCI_RH_SUSPENDED) {
 
-		/*
-		 * Some systems don't maintain the UHCI register values
-		 * during a PM suspend/resume cycle, so reinitialize
-		 * the Frame Number, Framelist Base Address, Interrupt
-		 * Enable, and Legacy Support registers.
-		 */
-		pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
-				0);
-		outw(uhci->frame_number, uhci->io_addr + USBFRNUM);
-		outl(uhci->fl->dma_handle, uhci->io_addr + USBFLBASEADD);
-		outw(USBINTR_TIMEOUT | USBINTR_RESUME | USBINTR_IOC |
-				USBINTR_SP, uhci->io_addr + USBINTR);
-		pci_write_config_word(to_pci_dev(uhci_dev(uhci)), USBLEGSUP,
-				USBLEGSUP_DEFAULT);
-		wakeup_hc(uhci);
-	}
-	spin_unlock_irq(&uhci->lock);
+	/* FIXME: Disable non-PME# remote wakeup? */
+
+	uhci->hc_inaccessible = 0;
+
+	/* The BIOS may have changed the controller settings during a
+	 * system wakeup.  Check it and reconfigure to avoid problems.
+	 */
+	check_and_reset_hc(uhci);
+	configure_hc(uhci);
+
+#ifndef CONFIG_USB_SUSPEND
+	/* Otherwise this would never happen */
+	wakeup_rh(uhci);
+#endif
+	if (uhci->rh_state == UHCI_RH_RESET)
+		suspend_rh(uhci, UHCI_RH_SUSPENDED);
 
-	hcd->state = HC_STATE_RUNNING;
+	spin_unlock_irq(&uhci->lock);
 	return 0;
 }
 #endif
@@ -792,6 +878,8 @@ static const struct hc_driver uhci_driver = {
 #ifdef CONFIG_PM
 	.suspend =		uhci_suspend,
 	.resume =		uhci_resume,
+	.hub_suspend =		uhci_rh_suspend,
+	.hub_resume =		uhci_rh_resume,
 #endif
 	.stop =			uhci_stop,
 

drivers/usb/host/uhci-hcd.h

@@ -41,6 +41,7 @@
 #define USBFRNUM	6
 #define USBFLBASEADD	8
 #define USBSOF		12
+#define   USBSOF_DEFAULT	64	/* Frame length is exactly 1 ms */
 
 /* USB port status and control registers */
 #define USBPORTSC1	16
@@ -66,6 +67,8 @@
 /* Legacy support register */
 #define USBLEGSUP		0xc0
 #define   USBLEGSUP_DEFAULT	0x2000	/* only PIRQ enable set */
+#define   USBLEGSUP_RWC		0x8f00	/* the R/WC bits */
+#define   USBLEGSUP_RO		0x5040	/* R/O and reserved bits */
 
 #define UHCI_NULL_DATA_SIZE	0x7FF	/* for UHCI controller TD */
 
@@ -325,8 +328,9 @@ static inline int __interval_to_skel(int interval)
  */
 enum uhci_rh_state {
 	/* In the next 4 states the HC must be halted */
-	UHCI_RH_RESET,
+	UHCI_RH_RESET,			/* These two must come first */
 	UHCI_RH_SUSPENDED,
+
 	UHCI_RH_AUTO_STOPPED,
 	UHCI_RH_RESUMING,
 
@@ -334,7 +338,8 @@ enum uhci_rh_state {
 	 * can legally appear either way */
 	UHCI_RH_SUSPENDING,
 
-	/* In the next two states it's an error if the HC is halted */
+	/* In the next two states it's an error if the HC is halted.
+	 * These two must come last */
 	UHCI_RH_RUNNING,		/* The normal state */
 	UHCI_RH_RUNNING_NODEVS,		/* Running with no devices attached */
 };
@@ -376,6 +381,7 @@ struct uhci_hcd {
 	unsigned int scan_in_progress:1;	/* Schedule scan is running */
 	unsigned int need_rescan:1;		/* Redo the schedule scan */
 	unsigned int resume_detect:1;		/* Need a Global Resume */
+	unsigned int hc_inaccessible:1;		/* HC is suspended or dead */
 
 	/* Support for port suspend/resume/reset */
 	unsigned long port_c_suspend;		/* Bit-arrays of ports */

drivers/usb/host/uhci-hub.c

@@ -54,6 +54,9 @@ static int uhci_hub_status_data(struct usb_hcd *hcd, char *buf)
 	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 	int port;
 
+	if (uhci->hc_inaccessible)
+		return 0;
+
 	*buf = 0;
 	for (port = 0; port < uhci->rh_numports; ++port) {
 		if ((inw(uhci->io_addr + USBPORTSC1 + port * 2) & RWC_BITS) ||
@@ -150,6 +153,9 @@ static int uhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 	u16 wPortChange, wPortStatus;
 	unsigned long flags;
 
+	if (uhci->hc_inaccessible)
+		return -ETIMEDOUT;
+
 	spin_lock_irqsave(&uhci->lock, flags);
 	switch (typeReq) {