power: reset: corrections for simple syscon reboot driver

[linux-2.6/btrfs-unstable.git] / drivers / usb / dwc2 / hcd_ddma.c

/*
 * 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 (!hsotg) {
                pr_err("hsotg = %p\n", hsotg);
                return;
        }

        if (!qh->channel) {
                dev_err(hsotg->dev, "qh->channel = %p\n", qh->channel);
                return;
        }

        if (!hsotg->frame_list) {
                dev_err(hsotg->dev, "hsotg->frame_list = %p\n",
                        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)) {
                if (hsotg->core_params->uframe_sched > 0)
                        hsotg->available_host_channels++;
                else
                        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->core_params->uframe_sched > 0 ||
             !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 - (chan->max_packet - 1))
                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;

        if (!qtd->urb)
                return -EINVAL;

        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_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, 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) {
                        if (qtd->urb) {
                                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, 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_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__);

        if (!urb)
                return -EINVAL;

        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, qtd, 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)) {
                                qtd = NULL;
                                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);
        }
}