staging: HCD descriptor DMA support for the DWC2 driver

This file contains code to support the HCD descriptor DMA mode of
the controller

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dwc2/hcd_ddma.c

@@ -0,0 +1,1196 @@
+/*
+ * hcd_ddma.c - DesignWare HS OTG Controller descriptor DMA routines
+ *
+ * Copyright (C) 2004-2013 Synopsys, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the above-listed copyright holders may not be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * ALTERNATIVELY, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") as published by the Free Software
+ * Foundation; either version 2 of the License, or (at your option) any
+ * later version.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * This file contains the Descriptor DMA implementation for Host mode
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include <linux/usb/hcd.h>
+#include <linux/usb/ch11.h>
+
+#include "core.h"
+#include "hcd.h"
+
+static u16 dwc2_frame_list_idx(u16 frame)
+{
+	return frame & (FRLISTEN_64_SIZE - 1);
+}
+
+static u16 dwc2_desclist_idx_inc(u16 idx, u16 inc, u8 speed)
+{
+	return (idx + inc) &
+		((speed == USB_SPEED_HIGH ? MAX_DMA_DESC_NUM_HS_ISOC :
+		  MAX_DMA_DESC_NUM_GENERIC) - 1);
+}
+
+static u16 dwc2_desclist_idx_dec(u16 idx, u16 inc, u8 speed)
+{
+	return (idx - inc) &
+		((speed == USB_SPEED_HIGH ? MAX_DMA_DESC_NUM_HS_ISOC :
+		  MAX_DMA_DESC_NUM_GENERIC) - 1);
+}
+
+static u16 dwc2_max_desc_num(struct dwc2_qh *qh)
+{
+	return (qh->ep_type == USB_ENDPOINT_XFER_ISOC &&
+		qh->dev_speed == USB_SPEED_HIGH) ?
+		MAX_DMA_DESC_NUM_HS_ISOC : MAX_DMA_DESC_NUM_GENERIC;
+}
+
+static u16 dwc2_frame_incr_val(struct dwc2_qh *qh)
+{
+	return qh->dev_speed == USB_SPEED_HIGH ?
+	       (qh->interval + 8 - 1) / 8 : qh->interval;
+}
+
+static int dwc2_desc_list_alloc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
+				gfp_t flags)
+{
+	qh->desc_list = dma_alloc_coherent(hsotg->dev,
+				sizeof(struct dwc2_hcd_dma_desc) *
+				dwc2_max_desc_num(qh), &qh->desc_list_dma,
+				flags);
+
+	if (!qh->desc_list)
+		return -ENOMEM;
+
+	memset(qh->desc_list, 0,
+	       sizeof(struct dwc2_hcd_dma_desc) * dwc2_max_desc_num(qh));
+
+	qh->n_bytes = kzalloc(sizeof(u32) * dwc2_max_desc_num(qh), flags);
+	if (!qh->n_bytes) {
+		dma_free_coherent(hsotg->dev, sizeof(struct dwc2_hcd_dma_desc)
+				  * dwc2_max_desc_num(qh), qh->desc_list,
+				  qh->desc_list_dma);
+		qh->desc_list = NULL;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void dwc2_desc_list_free(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
+{
+	if (qh->desc_list) {
+		dma_free_coherent(hsotg->dev, sizeof(struct dwc2_hcd_dma_desc)
+				  * dwc2_max_desc_num(qh), qh->desc_list,
+				  qh->desc_list_dma);
+		qh->desc_list = NULL;
+	}
+
+	kfree(qh->n_bytes);
+	qh->n_bytes = NULL;
+}
+
+static int dwc2_frame_list_alloc(struct dwc2_hsotg *hsotg, gfp_t mem_flags)
+{
+	if (hsotg->frame_list)
+		return 0;
+
+	hsotg->frame_list = dma_alloc_coherent(hsotg->dev,
+					       4 * FRLISTEN_64_SIZE,
+					       &hsotg->frame_list_dma,
+					       mem_flags);
+	if (!hsotg->frame_list)
+		return -ENOMEM;
+
+	memset(hsotg->frame_list, 0, 4 * FRLISTEN_64_SIZE);
+	return 0;
+}
+
+static void dwc2_frame_list_free(struct dwc2_hsotg *hsotg)
+{
+	u32 *frame_list;
+	dma_addr_t frame_list_dma;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hsotg->lock, flags);
+
+	if (!hsotg->frame_list) {
+		spin_unlock_irqrestore(&hsotg->lock, flags);
+		return;
+	}
+
+	frame_list = hsotg->frame_list;
+	frame_list_dma = hsotg->frame_list_dma;
+	hsotg->frame_list = NULL;
+
+	spin_unlock_irqrestore(&hsotg->lock, flags);
+
+	dma_free_coherent(hsotg->dev, 4 * FRLISTEN_64_SIZE, frame_list,
+			  frame_list_dma);
+}
+
+static void dwc2_per_sched_enable(struct dwc2_hsotg *hsotg, u32 fr_list_en)
+{
+	u32 hcfg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hsotg->lock, flags);
+
+	hcfg = readl(hsotg->regs + HCFG);
+	if (hcfg & HCFG_PERSCHEDENA) {
+		/* already enabled */
+		spin_unlock_irqrestore(&hsotg->lock, flags);
+		return;
+	}
+
+	writel(hsotg->frame_list_dma, hsotg->regs + HFLBADDR);
+
+	hcfg &= ~HCFG_FRLISTEN_MASK;
+	hcfg |= fr_list_en | HCFG_PERSCHEDENA;
+	dev_vdbg(hsotg->dev, "Enabling Periodic schedule\n");
+	writel(hcfg, hsotg->regs + HCFG);
+
+	spin_unlock_irqrestore(&hsotg->lock, flags);
+}
+
+static void dwc2_per_sched_disable(struct dwc2_hsotg *hsotg)
+{
+	u32 hcfg;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hsotg->lock, flags);
+
+	hcfg = readl(hsotg->regs + HCFG);
+	if (!(hcfg & HCFG_PERSCHEDENA)) {
+		/* already disabled */
+		spin_unlock_irqrestore(&hsotg->lock, flags);
+		return;
+	}
+
+	hcfg &= ~HCFG_PERSCHEDENA;
+	dev_vdbg(hsotg->dev, "Disabling Periodic schedule\n");
+	writel(hcfg, hsotg->regs + HCFG);
+
+	spin_unlock_irqrestore(&hsotg->lock, flags);
+}
+
+/*
+ * Activates/Deactivates FrameList entries for the channel based on endpoint
+ * servicing period
+ */
+static void dwc2_update_frame_list(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
+				   int enable)
+{
+	struct dwc2_host_chan *chan;
+	u16 i, j, inc;
+
+	if (!qh->channel) {
+		dev_err(hsotg->dev, "qh->channel = %p", qh->channel);
+		return;
+	}
+
+	if (!hsotg) {
+		dev_err(hsotg->dev, "------hsotg = %p", hsotg);
+		return;
+	}
+
+	if (!hsotg->frame_list) {
+		dev_err(hsotg->dev, "-------hsotg->frame_list = %p",
+			hsotg->frame_list);
+		return;
+	}
+
+	chan = qh->channel;
+	inc = dwc2_frame_incr_val(qh);
+	if (qh->ep_type == USB_ENDPOINT_XFER_ISOC)
+		i = dwc2_frame_list_idx(qh->sched_frame);
+	else
+		i = 0;
+
+	j = i;
+	do {
+		if (enable)
+			hsotg->frame_list[j] |= 1 << chan->hc_num;
+		else
+			hsotg->frame_list[j] &= ~(1 << chan->hc_num);
+		j = (j + inc) & (FRLISTEN_64_SIZE - 1);
+	} while (j != i);
+
+	if (!enable)
+		return;
+
+	chan->schinfo = 0;
+	if (chan->speed == USB_SPEED_HIGH && qh->interval) {
+		j = 1;
+		/* TODO - check this */
+		inc = (8 + qh->interval - 1) / qh->interval;
+		for (i = 0; i < inc; i++) {
+			chan->schinfo |= j;
+			j = j << qh->interval;
+		}
+	} else {
+		chan->schinfo = 0xff;
+	}
+}
+
+static void dwc2_release_channel_ddma(struct dwc2_hsotg *hsotg,
+				      struct dwc2_qh *qh)
+{
+	struct dwc2_host_chan *chan = qh->channel;
+
+	if (dwc2_qh_is_non_per(qh))
+		hsotg->non_periodic_channels--;
+	else
+		dwc2_update_frame_list(hsotg, qh, 0);
+
+	/*
+	 * The condition is added to prevent double cleanup try in case of
+	 * device disconnect. See channel cleanup in dwc2_hcd_disconnect().
+	 */
+	if (chan->qh) {
+		if (!list_empty(&chan->hc_list_entry))
+			list_del(&chan->hc_list_entry);
+		dwc2_hc_cleanup(hsotg, chan);
+		list_add_tail(&chan->hc_list_entry, &hsotg->free_hc_list);
+		chan->qh = NULL;
+	}
+
+	qh->channel = NULL;
+	qh->ntd = 0;
+
+	if (qh->desc_list)
+		memset(qh->desc_list, 0, sizeof(struct dwc2_hcd_dma_desc) *
+		       dwc2_max_desc_num(qh));
+}
+
+/**
+ * dwc2_hcd_qh_init_ddma() - Initializes a QH structure's Descriptor DMA
+ * related members
+ *
+ * @hsotg: The HCD state structure for the DWC OTG controller
+ * @qh:    The QH to init
+ *
+ * Return: 0 if successful, negative error code otherwise
+ *
+ * Allocates memory for the descriptor list. For the first periodic QH,
+ * allocates memory for the FrameList and enables periodic scheduling.
+ */
+int dwc2_hcd_qh_init_ddma(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
+			  gfp_t mem_flags)
+{
+	int retval;
+
+	if (qh->do_split) {
+		dev_err(hsotg->dev,
+			"SPLIT Transfers are not supported in Descriptor DMA mode.\n");
+		retval = -EINVAL;
+		goto err0;
+	}
+
+	retval = dwc2_desc_list_alloc(hsotg, qh, mem_flags);
+	if (retval)
+		goto err0;
+
+	if (qh->ep_type == USB_ENDPOINT_XFER_ISOC ||
+	    qh->ep_type == USB_ENDPOINT_XFER_INT) {
+		if (!hsotg->frame_list) {
+			retval = dwc2_frame_list_alloc(hsotg, mem_flags);
+			if (retval)
+				goto err1;
+			/* Enable periodic schedule on first periodic QH */
+			dwc2_per_sched_enable(hsotg, HCFG_FRLISTEN_64);
+		}
+	}
+
+	qh->ntd = 0;
+	return 0;
+
+err1:
+	dwc2_desc_list_free(hsotg, qh);
+err0:
+	return retval;
+}
+
+/**
+ * dwc2_hcd_qh_free_ddma() - Frees a QH structure's Descriptor DMA related
+ * members
+ *
+ * @hsotg: The HCD state structure for the DWC OTG controller
+ * @qh:    The QH to free
+ *
+ * Frees descriptor list memory associated with the QH. If QH is periodic and
+ * the last, frees FrameList memory and disables periodic scheduling.
+ */
+void dwc2_hcd_qh_free_ddma(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
+{
+	dwc2_desc_list_free(hsotg, qh);
+
+	/*
+	 * Channel still assigned due to some reasons.
+	 * Seen on Isoc URB dequeue. Channel halted but no subsequent
+	 * ChHalted interrupt to release the channel. Afterwards
+	 * when it comes here from endpoint disable routine
+	 * channel remains assigned.
+	 */
+	if (qh->channel)
+		dwc2_release_channel_ddma(hsotg, qh);
+
+	if ((qh->ep_type == USB_ENDPOINT_XFER_ISOC ||
+	     qh->ep_type == USB_ENDPOINT_XFER_INT) &&
+	    !hsotg->periodic_channels && hsotg->frame_list) {
+		dwc2_per_sched_disable(hsotg);
+		dwc2_frame_list_free(hsotg);
+	}
+}
+
+static u8 dwc2_frame_to_desc_idx(struct dwc2_qh *qh, u16 frame_idx)
+{
+	if (qh->dev_speed == USB_SPEED_HIGH)
+		/* Descriptor set (8 descriptors) index which is 8-aligned */
+		return (frame_idx & ((MAX_DMA_DESC_NUM_HS_ISOC / 8) - 1)) * 8;
+	else
+		return frame_idx & (MAX_DMA_DESC_NUM_GENERIC - 1);
+}
+
+/*
+ * Determine starting frame for Isochronous transfer.
+ * Few frames skipped to prevent race condition with HC.
+ */
+static u16 dwc2_calc_starting_frame(struct dwc2_hsotg *hsotg,
+				    struct dwc2_qh *qh, u16 *skip_frames)
+{
+	u16 frame;
+
+	hsotg->frame_number = dwc2_hcd_get_frame_number(hsotg);
+
+	/* sched_frame is always frame number (not uFrame) both in FS and HS! */
+
+	/*
+	 * skip_frames is used to limit activated descriptors number
+	 * to avoid the situation when HC services the last activated
+	 * descriptor firstly.
+	 * Example for FS:
+	 * Current frame is 1, scheduled frame is 3. Since HC always fetches
+	 * the descriptor corresponding to curr_frame+1, the descriptor
+	 * corresponding to frame 2 will be fetched. If the number of
+	 * descriptors is max=64 (or greather) the list will be fully programmed
+	 * with Active descriptors and it is possible case (rare) that the
+	 * latest descriptor(considering rollback) corresponding to frame 2 will
+	 * be serviced first. HS case is more probable because, in fact, up to
+	 * 11 uframes (16 in the code) may be skipped.
+	 */
+	if (qh->dev_speed == USB_SPEED_HIGH) {
+		/*
+		 * Consider uframe counter also, to start xfer asap. If half of
+		 * the frame elapsed skip 2 frames otherwise just 1 frame.
+		 * Starting descriptor index must be 8-aligned, so if the
+		 * current frame is near to complete the next one is skipped as
+		 * well.
+		 */
+		if (dwc2_micro_frame_num(hsotg->frame_number) >= 5) {
+			*skip_frames = 2 * 8;
+			frame = dwc2_frame_num_inc(hsotg->frame_number,
+						   *skip_frames);
+		} else {
+			*skip_frames = 1 * 8;
+			frame = dwc2_frame_num_inc(hsotg->frame_number,
+						   *skip_frames);
+		}
+
+		frame = dwc2_full_frame_num(frame);
+	} else {
+		/*
+		 * Two frames are skipped for FS - the current and the next.
+		 * But for descriptor programming, 1 frame (descriptor) is
+		 * enough, see example above.
+		 */
+		*skip_frames = 1;
+		frame = dwc2_frame_num_inc(hsotg->frame_number, 2);
+	}
+
+	return frame;
+}
+
+/*
+ * Calculate initial descriptor index for isochronous transfer based on
+ * scheduled frame
+ */
+static u16 dwc2_recalc_initial_desc_idx(struct dwc2_hsotg *hsotg,
+					struct dwc2_qh *qh)
+{
+	u16 frame, fr_idx, fr_idx_tmp, skip_frames;
+
+	/*
+	 * With current ISOC processing algorithm the channel is being released
+	 * when no more QTDs in the list (qh->ntd == 0). Thus this function is
+	 * called only when qh->ntd == 0 and qh->channel == 0.
+	 *
+	 * So qh->channel != NULL branch is not used and just not removed from
+	 * the source file. It is required for another possible approach which
+	 * is, do not disable and release the channel when ISOC session
+	 * completed, just move QH to inactive schedule until new QTD arrives.
+	 * On new QTD, the QH moved back to 'ready' schedule, starting frame and
+	 * therefore starting desc_index are recalculated. In this case channel
+	 * is released only on ep_disable.
+	 */
+
+	/*
+	 * Calculate starting descriptor index. For INTERRUPT endpoint it is
+	 * always 0.
+	 */
+	if (qh->channel) {
+		frame = dwc2_calc_starting_frame(hsotg, qh, &skip_frames);
+		/*
+		 * Calculate initial descriptor index based on FrameList current
+		 * bitmap and servicing period
+		 */
+		fr_idx_tmp = dwc2_frame_list_idx(frame);
+		fr_idx = (FRLISTEN_64_SIZE +
+			  dwc2_frame_list_idx(qh->sched_frame) - fr_idx_tmp)
+			 % dwc2_frame_incr_val(qh);
+		fr_idx = (fr_idx + fr_idx_tmp) % FRLISTEN_64_SIZE;
+	} else {
+		qh->sched_frame = dwc2_calc_starting_frame(hsotg, qh,
+							   &skip_frames);
+		fr_idx = dwc2_frame_list_idx(qh->sched_frame);
+	}
+
+	qh->td_first = qh->td_last = dwc2_frame_to_desc_idx(qh, fr_idx);
+
+	return skip_frames;
+}
+
+#define ISOC_URB_GIVEBACK_ASAP
+
+#define MAX_ISOC_XFER_SIZE_FS	1023
+#define MAX_ISOC_XFER_SIZE_HS	3072
+#define DESCNUM_THRESHOLD	4
+
+static void dwc2_fill_host_isoc_dma_desc(struct dwc2_hsotg *hsotg,
+					 struct dwc2_qtd *qtd,
+					 struct dwc2_qh *qh, u32 max_xfer_size,
+					 u16 idx)
+{
+	struct dwc2_hcd_dma_desc *dma_desc = &qh->desc_list[idx];
+	struct dwc2_hcd_iso_packet_desc *frame_desc;
+
+	memset(dma_desc, 0, sizeof(*dma_desc));
+	frame_desc = &qtd->urb->iso_descs[qtd->isoc_frame_index_last];
+
+	if (frame_desc->length > max_xfer_size)
+		qh->n_bytes[idx] = max_xfer_size;
+	else
+		qh->n_bytes[idx] = frame_desc->length;
+
+	dma_desc->buf = (u32)(qtd->urb->dma + frame_desc->offset);
+	dma_desc->status = qh->n_bytes[idx] << HOST_DMA_ISOC_NBYTES_SHIFT &
+			   HOST_DMA_ISOC_NBYTES_MASK;
+
+#ifdef ISOC_URB_GIVEBACK_ASAP
+	/* Set IOC for each descriptor corresponding to last frame of URB */
+	if (qtd->isoc_frame_index_last == qtd->urb->packet_count)
+		dma_desc->status |= HOST_DMA_IOC;
+#endif
+
+	qh->ntd++;
+	qtd->isoc_frame_index_last++;
+}
+
+static void dwc2_init_isoc_dma_desc(struct dwc2_hsotg *hsotg,
+				    struct dwc2_qh *qh, u16 skip_frames)
+{
+	struct dwc2_qtd *qtd;
+	u32 max_xfer_size;
+	u16 idx, inc, n_desc, ntd_max = 0;
+
+	idx = qh->td_last;
+	inc = qh->interval;
+	n_desc = 0;
+
+	if (qh->interval) {
+		ntd_max = (dwc2_max_desc_num(qh) + qh->interval - 1) /
+				qh->interval;
+		if (skip_frames && !qh->channel)
+			ntd_max -= skip_frames / qh->interval;
+	}
+
+	max_xfer_size = qh->dev_speed == USB_SPEED_HIGH ?
+			MAX_ISOC_XFER_SIZE_HS : MAX_ISOC_XFER_SIZE_FS;
+
+	list_for_each_entry(qtd, &qh->qtd_list, qtd_list_entry) {
+		while (qh->ntd < ntd_max && qtd->isoc_frame_index_last <
+						qtd->urb->packet_count) {
+			if (n_desc > 1)
+				qh->desc_list[n_desc - 1].status |= HOST_DMA_A;
+			dwc2_fill_host_isoc_dma_desc(hsotg, qtd, qh,
+						     max_xfer_size, idx);
+			idx = dwc2_desclist_idx_inc(idx, inc, qh->dev_speed);
+			n_desc++;
+		}
+		qtd->in_process = 1;
+	}
+
+	qh->td_last = idx;
+
+#ifdef ISOC_URB_GIVEBACK_ASAP
+	/* Set IOC for last descriptor if descriptor list is full */
+	if (qh->ntd == ntd_max) {
+		idx = dwc2_desclist_idx_dec(qh->td_last, inc, qh->dev_speed);
+		qh->desc_list[idx].status |= HOST_DMA_IOC;
+	}
+#else
+	/*
+	 * Set IOC bit only for one descriptor. Always try to be ahead of HW
+	 * processing, i.e. on IOC generation driver activates next descriptor
+	 * but core continues to process descriptors following the one with IOC
+	 * set.
+	 */
+
+	if (n_desc > DESCNUM_THRESHOLD)
+		/*
+		 * Move IOC "up". Required even if there is only one QTD
+		 * in the list, because QTDs might continue to be queued,
+		 * but during the activation it was only one queued.
+		 * Actually more than one QTD might be in the list if this
+		 * function called from XferCompletion - QTDs was queued during
+		 * HW processing of the previous descriptor chunk.
+		 */
+		idx = dwc2_desclist_idx_dec(idx, inc * ((qh->ntd + 1) / 2),
+					    qh->dev_speed);
+	else
+		/*
+		 * Set the IOC for the latest descriptor if either number of
+		 * descriptors is not greater than threshold or no more new
+		 * descriptors activated
+		 */
+		idx = dwc2_desclist_idx_dec(qh->td_last, inc, qh->dev_speed);
+
+	qh->desc_list[idx].status |= HOST_DMA_IOC;
+#endif
+
+	if (n_desc) {
+		qh->desc_list[n_desc - 1].status |= HOST_DMA_A;
+		if (n_desc > 1)
+			qh->desc_list[0].status |= HOST_DMA_A;
+	}
+}
+
+static void dwc2_fill_host_dma_desc(struct dwc2_hsotg *hsotg,
+				    struct dwc2_host_chan *chan,
+				    struct dwc2_qtd *qtd, struct dwc2_qh *qh,
+				    int n_desc)
+{
+	struct dwc2_hcd_dma_desc *dma_desc = &qh->desc_list[n_desc];
+	int len = chan->xfer_len;
+
+	if (len > MAX_DMA_DESC_SIZE)
+		len = MAX_DMA_DESC_SIZE - chan->max_packet + 1;
+
+	if (chan->ep_is_in) {
+		int num_packets;
+
+		if (len > 0 && chan->max_packet)
+			num_packets = (len + chan->max_packet - 1)
+					/ chan->max_packet;
+		else
+			/* Need 1 packet for transfer length of 0 */
+			num_packets = 1;
+
+		/* Always program an integral # of packets for IN transfers */
+		len = num_packets * chan->max_packet;
+	}
+
+	dma_desc->status = len << HOST_DMA_NBYTES_SHIFT & HOST_DMA_NBYTES_MASK;
+	qh->n_bytes[n_desc] = len;
+
+	if (qh->ep_type == USB_ENDPOINT_XFER_CONTROL &&
+	    qtd->control_phase == DWC2_CONTROL_SETUP)
+		dma_desc->status |= HOST_DMA_SUP;
+
+	dma_desc->buf = (u32)chan->xfer_dma;
+
+	/*
+	 * Last (or only) descriptor of IN transfer with actual size less
+	 * than MaxPacket
+	 */
+	if (len > chan->xfer_len) {
+		chan->xfer_len = 0;
+	} else {
+		chan->xfer_dma += len;
+		chan->xfer_len -= len;
+	}
+}
+
+static void dwc2_init_non_isoc_dma_desc(struct dwc2_hsotg *hsotg,
+					struct dwc2_qh *qh)
+{
+	struct dwc2_qtd *qtd;
+	struct dwc2_host_chan *chan = qh->channel;
+	int n_desc = 0;
+
+	dev_vdbg(hsotg->dev, "%s(): qh=%p dma=%08lx len=%d\n", __func__, qh,
+		 (unsigned long)chan->xfer_dma, chan->xfer_len);
+
+	/*
+	 * Start with chan->xfer_dma initialized in assign_and_init_hc(), then
+	 * if SG transfer consists of multiple URBs, this pointer is re-assigned
+	 * to the buffer of the currently processed QTD. For non-SG request
+	 * there is always one QTD active.
+	 */
+
+	list_for_each_entry(qtd, &qh->qtd_list, qtd_list_entry) {
+		dev_vdbg(hsotg->dev, "qtd=%p\n", qtd);
+
+		if (n_desc) {
+			/* SG request - more than 1 QTD */
+			chan->xfer_dma = qtd->urb->dma +
+					qtd->urb->actual_length;
+			chan->xfer_len = qtd->urb->length -
+					qtd->urb->actual_length;
+			dev_vdbg(hsotg->dev, "buf=%08lx len=%d\n",
+				 (unsigned long)chan->xfer_dma, chan->xfer_len);
+		}
+
+		qtd->n_desc = 0;
+		do {
+			if (n_desc > 1) {
+				qh->desc_list[n_desc - 1].status |= HOST_DMA_A;
+				dev_vdbg(hsotg->dev,
+					 "set A bit in desc %d (%p)\n",
+					 n_desc - 1,
+					 &qh->desc_list[n_desc - 1]);
+			}
+			dwc2_fill_host_dma_desc(hsotg, chan, qtd, qh, n_desc);
+			dev_vdbg(hsotg->dev,
+				 "desc %d (%p) buf=%08x status=%08x\n",
+				 n_desc, &qh->desc_list[n_desc],
+				 qh->desc_list[n_desc].buf,
+				 qh->desc_list[n_desc].status);
+			qtd->n_desc++;
+			n_desc++;
+		} while (chan->xfer_len > 0 &&
+			 n_desc != MAX_DMA_DESC_NUM_GENERIC);
+
+		dev_vdbg(hsotg->dev, "n_desc=%d\n", n_desc);
+		qtd->in_process = 1;
+		if (qh->ep_type == USB_ENDPOINT_XFER_CONTROL)
+			break;
+		if (n_desc == MAX_DMA_DESC_NUM_GENERIC)
+			break;
+	}
+
+	if (n_desc) {
+		qh->desc_list[n_desc - 1].status |=
+				HOST_DMA_IOC | HOST_DMA_EOL | HOST_DMA_A;
+		dev_vdbg(hsotg->dev, "set IOC/EOL/A bits in desc %d (%p)\n",
+			 n_desc - 1, &qh->desc_list[n_desc - 1]);
+		if (n_desc > 1) {
+			qh->desc_list[0].status |= HOST_DMA_A;
+			dev_vdbg(hsotg->dev, "set A bit in desc 0 (%p)\n",
+				 &qh->desc_list[0]);
+		}
+		chan->ntd = n_desc;
+	}
+}
+
+/**
+ * dwc2_hcd_start_xfer_ddma() - Starts a transfer in Descriptor DMA mode
+ *
+ * @hsotg: The HCD state structure for the DWC OTG controller
+ * @qh:    The QH to init
+ *
+ * Return: 0 if successful, negative error code otherwise
+ *
+ * For Control and Bulk endpoints, initializes descriptor list and starts the
+ * transfer. For Interrupt and Isochronous endpoints, initializes descriptor
+ * list then updates FrameList, marking appropriate entries as active.
+ *
+ * For Isochronous endpoints the starting descriptor index is calculated based
+ * on the scheduled frame, but only on the first transfer descriptor within a
+ * session. Then the transfer is started via enabling the channel.
+ *
+ * For Isochronous endpoints the channel is not halted on XferComplete
+ * interrupt so remains assigned to the endpoint(QH) until session is done.
+ */
+void dwc2_hcd_start_xfer_ddma(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
+{
+	/* Channel is already assigned */
+	struct dwc2_host_chan *chan = qh->channel;
+	u16 skip_frames = 0;
+
+	switch (chan->ep_type) {
+	case USB_ENDPOINT_XFER_CONTROL:
+	case USB_ENDPOINT_XFER_BULK:
+		dwc2_init_non_isoc_dma_desc(hsotg, qh);
+		dwc2_hc_start_transfer_ddma(hsotg, chan);
+		break;
+	case USB_ENDPOINT_XFER_INT:
+		dwc2_init_non_isoc_dma_desc(hsotg, qh);
+		dwc2_update_frame_list(hsotg, qh, 1);
+		dwc2_hc_start_transfer_ddma(hsotg, chan);
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		if (!qh->ntd)
+			skip_frames = dwc2_recalc_initial_desc_idx(hsotg, qh);
+		dwc2_init_isoc_dma_desc(hsotg, qh, skip_frames);
+
+		if (!chan->xfer_started) {
+			dwc2_update_frame_list(hsotg, qh, 1);
+
+			/*
+			 * Always set to max, instead of actual size. Otherwise
+			 * ntd will be changed with channel being enabled. Not
+			 * recommended.
+			 */
+			chan->ntd = dwc2_max_desc_num(qh);
+
+			/* Enable channel only once for ISOC */
+			dwc2_hc_start_transfer_ddma(hsotg, chan);
+		}
+
+		break;
+	default:
+		break;
+	}
+}
+
+#define DWC2_CMPL_DONE		1
+#define DWC2_CMPL_STOP		2
+
+static int dwc2_cmpl_host_isoc_dma_desc(struct dwc2_hsotg *hsotg,
+					struct dwc2_host_chan *chan,
+					struct dwc2_qtd *qtd,
+					struct dwc2_qh *qh, u16 idx)
+{
+	struct dwc2_hcd_dma_desc *dma_desc = &qh->desc_list[idx];
+	struct dwc2_hcd_iso_packet_desc *frame_desc;
+	u16 remain = 0;
+	int rc = 0;
+
+	frame_desc = &qtd->urb->iso_descs[qtd->isoc_frame_index_last];
+	dma_desc->buf = (u32)(qtd->urb->dma + frame_desc->offset);
+	if (chan->ep_is_in)
+		remain = dma_desc->status >> HOST_DMA_ISOC_NBYTES_SHIFT &
+			HOST_DMA_ISOC_NBYTES_MASK >> HOST_DMA_ISOC_NBYTES_SHIFT;
+
+	if ((dma_desc->status & HOST_DMA_STS_MASK) == HOST_DMA_STS_PKTERR) {
+		/*
+		 * XactError, or unable to complete all the transactions
+		 * in the scheduled micro-frame/frame, both indicated by
+		 * HOST_DMA_STS_PKTERR
+		 */
+		qtd->urb->error_count++;
+		frame_desc->actual_length = qh->n_bytes[idx] - remain;
+		frame_desc->status = -EPROTO;
+	} else {
+		/* Success */
+		frame_desc->actual_length = qh->n_bytes[idx] - remain;
+		frame_desc->status = 0;
+	}
+
+	if (++qtd->isoc_frame_index == qtd->urb->packet_count) {
+		/*
+		 * urb->status is not used for isoc transfers here. The
+		 * individual frame_desc status are used instead.
+		 */
+		dwc2_host_complete(hsotg, qtd->urb->priv, qtd->urb, 0);
+		dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
+
+		/*
+		 * This check is necessary because urb_dequeue can be called
+		 * from urb complete callback (sound driver for example). All
+		 * pending URBs are dequeued there, so no need for further
+		 * processing.
+		 */
+		if (chan->halt_status == DWC2_HC_XFER_URB_DEQUEUE)
+			return -1;
+		rc = DWC2_CMPL_DONE;
+	}
+
+	qh->ntd--;
+
+	/* Stop if IOC requested descriptor reached */
+	if (dma_desc->status & HOST_DMA_IOC)
+		rc = DWC2_CMPL_STOP;
+
+	return rc;
+}
+
+static void dwc2_complete_isoc_xfer_ddma(struct dwc2_hsotg *hsotg,
+					 struct dwc2_host_chan *chan,
+					 enum dwc2_halt_status halt_status)
+{
+	struct dwc2_hcd_iso_packet_desc *frame_desc;
+	struct dwc2_qtd *qtd, *qtd_tmp;
+	struct dwc2_qh *qh;
+	u16 idx;
+	int rc;
+
+	qh = chan->qh;
+	idx = qh->td_first;
+
+	if (chan->halt_status == DWC2_HC_XFER_URB_DEQUEUE) {
+		list_for_each_entry(qtd, &qh->qtd_list, qtd_list_entry)
+			qtd->in_process = 0;
+		return;
+	}
+
+	if (halt_status == DWC2_HC_XFER_AHB_ERR ||
+	    halt_status == DWC2_HC_XFER_BABBLE_ERR) {
+		/*
+		 * Channel is halted in these error cases, considered as serious
+		 * issues.
+		 * Complete all URBs marking all frames as failed, irrespective
+		 * whether some of the descriptors (frames) succeeded or not.
+		 * Pass error code to completion routine as well, to update
+		 * urb->status, some of class drivers might use it to stop
+		 * queing transfer requests.
+		 */
+		int err = halt_status == DWC2_HC_XFER_AHB_ERR ?
+			  -EIO : -EOVERFLOW;
+
+		list_for_each_entry_safe(qtd, qtd_tmp, &qh->qtd_list,
+					 qtd_list_entry) {
+			for (idx = 0; idx < qtd->urb->packet_count; idx++) {
+				frame_desc = &qtd->urb->iso_descs[idx];
+				frame_desc->status = err;
+			}
+
+			dwc2_host_complete(hsotg, qtd->urb->priv, qtd->urb,
+					   err);
+			dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
+		}
+
+		return;
+	}
+
+	list_for_each_entry_safe(qtd, qtd_tmp, &qh->qtd_list, qtd_list_entry) {
+		if (!qtd->in_process)
+			break;
+		do {
+			rc = dwc2_cmpl_host_isoc_dma_desc(hsotg, chan, qtd, qh,
+							  idx);
+			if (rc < 0)
+				return;
+			idx = dwc2_desclist_idx_inc(idx, qh->interval,
+						    chan->speed);
+			if (rc == DWC2_CMPL_STOP)
+				goto stop_scan;
+			if (rc == DWC2_CMPL_DONE)
+				break;
+		} while (idx != qh->td_first);
+	}
+
+stop_scan:
+	qh->td_first = idx;
+}
+
+static int dwc2_update_non_isoc_urb_state_ddma(struct dwc2_hsotg *hsotg,
+					struct dwc2_host_chan *chan,
+					struct dwc2_qtd *qtd,
+					struct dwc2_hcd_dma_desc *dma_desc,
+					enum dwc2_halt_status halt_status,
+					u32 n_bytes, int *xfer_done)
+{
+	struct dwc2_hcd_urb *urb = qtd->urb;
+	u16 remain = 0;
+
+	if (chan->ep_is_in)
+		remain = dma_desc->status >> HOST_DMA_NBYTES_SHIFT &
+			 HOST_DMA_NBYTES_MASK >> HOST_DMA_NBYTES_SHIFT;
+
+	dev_vdbg(hsotg->dev, "remain=%d dwc2_urb=%p\n", remain, urb);
+
+	if (halt_status == DWC2_HC_XFER_AHB_ERR) {
+		dev_err(hsotg->dev, "EIO\n");
+		urb->status = -EIO;
+		return 1;
+	}
+
+	if ((dma_desc->status & HOST_DMA_STS_MASK) == HOST_DMA_STS_PKTERR) {
+		switch (halt_status) {
+		case DWC2_HC_XFER_STALL:
+			dev_vdbg(hsotg->dev, "Stall\n");
+			urb->status = -EPIPE;
+			break;
+		case DWC2_HC_XFER_BABBLE_ERR:
+			dev_err(hsotg->dev, "Babble\n");
+			urb->status = -EOVERFLOW;
+			break;
+		case DWC2_HC_XFER_XACT_ERR:
+			dev_err(hsotg->dev, "XactErr\n");
+			urb->status = -EPROTO;
+			break;
+		default:
+			dev_err(hsotg->dev,
+				"%s: Unhandled descriptor error status (%d)\n",
+				__func__, halt_status);
+			break;
+		}
+		return 1;
+	}
+
+	if (dma_desc->status & HOST_DMA_A) {
+		dev_vdbg(hsotg->dev,
+			 "Active descriptor encountered on channel %d\n",
+			 chan->hc_num);
+		return 0;
+	}
+
+	if (chan->ep_type == USB_ENDPOINT_XFER_CONTROL) {
+		if (qtd->control_phase == DWC2_CONTROL_DATA) {
+			urb->actual_length += n_bytes - remain;
+			if (remain || urb->actual_length >= urb->length) {
+				/*
+				 * For Control Data stage do not set urb->status
+				 * to 0, to prevent URB callback. Set it when
+				 * Status phase is done. See below.
+				 */
+				*xfer_done = 1;
+			}
+		} else if (qtd->control_phase == DWC2_CONTROL_STATUS) {
+			urb->status = 0;
+			*xfer_done = 1;
+		}
+		/* No handling for SETUP stage */
+	} else {
+		/* BULK and INTR */
+		urb->actual_length += n_bytes - remain;
+		dev_vdbg(hsotg->dev, "length=%d actual=%d\n", urb->length,
+			 urb->actual_length);
+		if (remain || urb->actual_length >= urb->length) {
+			urb->status = 0;
+			*xfer_done = 1;
+		}
+	}
+
+	return 0;
+}
+
+static int dwc2_process_non_isoc_desc(struct dwc2_hsotg *hsotg,
+				      struct dwc2_host_chan *chan,
+				      int chnum, struct dwc2_qtd *qtd,
+				      int desc_num,
+				      enum dwc2_halt_status halt_status,
+				      int *xfer_done)
+{
+	struct dwc2_qh *qh = chan->qh;
+	struct dwc2_hcd_urb *urb = qtd->urb;
+	struct dwc2_hcd_dma_desc *dma_desc;
+	u32 n_bytes;
+	int failed;
+
+	dev_vdbg(hsotg->dev, "%s()\n", __func__);
+
+	dma_desc = &qh->desc_list[desc_num];
+	n_bytes = qh->n_bytes[desc_num];
+	dev_vdbg(hsotg->dev,
+		 "qtd=%p dwc2_urb=%p desc_num=%d desc=%p n_bytes=%d\n",
+		 qtd, urb, desc_num, dma_desc, n_bytes);
+	failed = dwc2_update_non_isoc_urb_state_ddma(hsotg, chan, qtd, dma_desc,
+						     halt_status, n_bytes,
+						     xfer_done);
+	if (failed || (*xfer_done && urb->status != -EINPROGRESS)) {
+		dwc2_host_complete(hsotg, urb->priv, urb, urb->status);
+		dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
+		dev_vdbg(hsotg->dev, "failed=%1x xfer_done=%1x status=%08x\n",
+			 failed, *xfer_done, urb->status);
+		return failed;
+	}
+
+	if (qh->ep_type == USB_ENDPOINT_XFER_CONTROL) {
+		switch (qtd->control_phase) {
+		case DWC2_CONTROL_SETUP:
+			if (urb->length > 0)
+				qtd->control_phase = DWC2_CONTROL_DATA;
+			else
+				qtd->control_phase = DWC2_CONTROL_STATUS;
+			dev_vdbg(hsotg->dev,
+				 "  Control setup transaction done\n");
+			break;
+		case DWC2_CONTROL_DATA:
+			if (*xfer_done) {
+				qtd->control_phase = DWC2_CONTROL_STATUS;
+				dev_vdbg(hsotg->dev,
+					 "  Control data transfer done\n");
+			} else if (desc_num + 1 == qtd->n_desc) {
+				/*
+				 * Last descriptor for Control data stage which
+				 * is not completed yet
+				 */
+				dwc2_hcd_save_data_toggle(hsotg, chan, chnum,
+							  qtd);
+			}
+			break;
+		default:
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static void dwc2_complete_non_isoc_xfer_ddma(struct dwc2_hsotg *hsotg,
+					     struct dwc2_host_chan *chan,
+					     int chnum,
+					     enum dwc2_halt_status halt_status)
+{
+	struct list_head *qtd_item, *qtd_tmp;
+	struct dwc2_qh *qh = chan->qh;
+	struct dwc2_qtd *qtd = NULL;
+	int xfer_done;
+	int desc_num = 0;
+
+	if (chan->halt_status == DWC2_HC_XFER_URB_DEQUEUE) {
+		list_for_each_entry(qtd, &qh->qtd_list, qtd_list_entry)
+			qtd->in_process = 0;
+		return;
+	}
+
+	list_for_each_safe(qtd_item, qtd_tmp, &qh->qtd_list) {
+		int i;
+
+		qtd = list_entry(qtd_item, struct dwc2_qtd, qtd_list_entry);
+		xfer_done = 0;
+
+		for (i = 0; i < qtd->n_desc; i++) {
+			if (dwc2_process_non_isoc_desc(hsotg, chan, chnum, qtd,
+						       desc_num, halt_status,
+						       &xfer_done))
+				break;
+			desc_num++;
+		}
+	}
+
+	if (qh->ep_type != USB_ENDPOINT_XFER_CONTROL) {
+		/*
+		 * Resetting the data toggle for bulk and interrupt endpoints
+		 * in case of stall. See handle_hc_stall_intr().
+		 */
+		if (halt_status == DWC2_HC_XFER_STALL)
+			qh->data_toggle = DWC2_HC_PID_DATA0;
+		else if (qtd)
+			dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);
+	}
+
+	if (halt_status == DWC2_HC_XFER_COMPLETE) {
+		if (chan->hcint & HCINTMSK_NYET) {
+			/*
+			 * Got a NYET on the last transaction of the transfer.
+			 * It means that the endpoint should be in the PING
+			 * state at the beginning of the next transfer.
+			 */
+			qh->ping_state = 1;
+		}
+	}
+}
+
+/**
+ * dwc2_hcd_complete_xfer_ddma() - Scans the descriptor list, updates URB's
+ * status and calls completion routine for the URB if it's done. Called from
+ * interrupt handlers.
+ *
+ * @hsotg:       The HCD state structure for the DWC OTG controller
+ * @chan:        Host channel the transfer is completed on
+ * @chnum:       Index of Host channel registers
+ * @halt_status: Reason the channel is being halted or just XferComplete
+ *               for isochronous transfers
+ *
+ * Releases the channel to be used by other transfers.
+ * In case of Isochronous endpoint the channel is not halted until the end of
+ * the session, i.e. QTD list is empty.
+ * If periodic channel released the FrameList is updated accordingly.
+ * Calls transaction selection routines to activate pending transfers.
+ */
+void dwc2_hcd_complete_xfer_ddma(struct dwc2_hsotg *hsotg,
+				 struct dwc2_host_chan *chan, int chnum,
+				 enum dwc2_halt_status halt_status)
+{
+	struct dwc2_qh *qh = chan->qh;
+	int continue_isoc_xfer = 0;
+	enum dwc2_transaction_type tr_type;
+
+	if (chan->ep_type == USB_ENDPOINT_XFER_ISOC) {
+		dwc2_complete_isoc_xfer_ddma(hsotg, chan, halt_status);
+
+		/* Release the channel if halted or session completed */
+		if (halt_status != DWC2_HC_XFER_COMPLETE ||
+		    list_empty(&qh->qtd_list)) {
+			/* Halt the channel if session completed */
+			if (halt_status == DWC2_HC_XFER_COMPLETE)
+				dwc2_hc_halt(hsotg, chan, halt_status);
+			dwc2_release_channel_ddma(hsotg, qh);
+			dwc2_hcd_qh_unlink(hsotg, qh);
+		} else {
+			/* Keep in assigned schedule to continue transfer */
+			list_move(&qh->qh_list_entry,
+				  &hsotg->periodic_sched_assigned);
+			continue_isoc_xfer = 1;
+		}
+		/*
+		 * Todo: Consider the case when period exceeds FrameList size.
+		 * Frame Rollover interrupt should be used.
+		 */
+	} else {
+		/*
+		 * Scan descriptor list to complete the URB(s), then release
+		 * the channel
+		 */
+		dwc2_complete_non_isoc_xfer_ddma(hsotg, chan, chnum,
+						 halt_status);
+		dwc2_release_channel_ddma(hsotg, qh);
+		dwc2_hcd_qh_unlink(hsotg, qh);
+
+		if (!list_empty(&qh->qtd_list)) {
+			/*
+			 * Add back to inactive non-periodic schedule on normal
+			 * completion
+			 */
+			dwc2_hcd_qh_add(hsotg, qh);
+		}
+	}
+
+	tr_type = dwc2_hcd_select_transactions(hsotg);
+	if (tr_type != DWC2_TRANSACTION_NONE || continue_isoc_xfer) {
+		if (continue_isoc_xfer) {
+			if (tr_type == DWC2_TRANSACTION_NONE)
+				tr_type = DWC2_TRANSACTION_PERIODIC;
+			else if (tr_type == DWC2_TRANSACTION_NON_PERIODIC)
+				tr_type = DWC2_TRANSACTION_ALL;
+		}
+		dwc2_hcd_queue_transactions(hsotg, tr_type);
+	}
+}