// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
/*
 * hcd_intr.c - DesignWare HS OTG Controller host-mode interrupt handling
 *
 * 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 interrupt handlers 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"

/*
 * If we get this many NAKs on a split transaction we'll slow down
 * retransmission.  A 1 here means delay after the first NAK.
 */
#define DWC2_NAKS_BEFORE_DELAY          3

/* This function is for debug only */
static void dwc2_track_missed_sofs(struct dwc2_hsotg *hsotg)
{
        u16 curr_frame_number = hsotg->frame_number;
        u16 expected = dwc2_frame_num_inc(hsotg->last_frame_num, 1);

        if (expected != curr_frame_number)
                dwc2_sch_vdbg(hsotg, "MISSED SOF %04x != %04x\n",
                              expected, curr_frame_number);

#ifdef CONFIG_USB_DWC2_TRACK_MISSED_SOFS
        if (hsotg->frame_num_idx < FRAME_NUM_ARRAY_SIZE) {
                if (expected != curr_frame_number) {
                        hsotg->frame_num_array[hsotg->frame_num_idx] =
                                        curr_frame_number;
                        hsotg->last_frame_num_array[hsotg->frame_num_idx] =
                                        hsotg->last_frame_num;
                        hsotg->frame_num_idx++;
                }
        } else if (!hsotg->dumped_frame_num_array) {
                int i;

                dev_info(hsotg->dev, "Frame     Last Frame\n");
                dev_info(hsotg->dev, "-----     ----------\n");
                for (i = 0; i < FRAME_NUM_ARRAY_SIZE; i++) {
                        dev_info(hsotg->dev, "0x%04x    0x%04x\n",
                                 hsotg->frame_num_array[i],
                                 hsotg->last_frame_num_array[i]);
                }
                hsotg->dumped_frame_num_array = 1;
        }
#endif
        hsotg->last_frame_num = curr_frame_number;
}

static void dwc2_hc_handle_tt_clear(struct dwc2_hsotg *hsotg,
                                    struct dwc2_host_chan *chan,
                                    struct dwc2_qtd *qtd)
{
        struct usb_device *root_hub = dwc2_hsotg_to_hcd(hsotg)->self.root_hub;
        struct urb *usb_urb;

        if (!chan->qh)
                return;

        if (chan->qh->dev_speed == USB_SPEED_HIGH)
                return;

        if (!qtd->urb)
                return;

        usb_urb = qtd->urb->priv;
        if (!usb_urb || !usb_urb->dev || !usb_urb->dev->tt)
                return;

        /*
         * The root hub doesn't really have a TT, but Linux thinks it
         * does because how could you have a "high speed hub" that
         * directly talks directly to low speed devices without a TT?
         * It's all lies.  Lies, I tell you.
         */
        if (usb_urb->dev->tt->hub == root_hub)
                return;

        if (qtd->urb->status != -EPIPE && qtd->urb->status != -EREMOTEIO) {
                chan->qh->tt_buffer_dirty = 1;
                if (usb_hub_clear_tt_buffer(usb_urb))
                        /* Clear failed; let's hope things work anyway */
                        chan->qh->tt_buffer_dirty = 0;
        }
}

/*
 * Handles the start-of-frame interrupt in host mode. Non-periodic
 * transactions may be queued to the DWC_otg controller for the current
 * (micro)frame. Periodic transactions may be queued to the controller
 * for the next (micro)frame.
 */
static void dwc2_sof_intr(struct dwc2_hsotg *hsotg)
{
        struct list_head *qh_entry;
        struct dwc2_qh *qh;
        enum dwc2_transaction_type tr_type;

        /* Clear interrupt */
        dwc2_writel(hsotg, GINTSTS_SOF, GINTSTS);

#ifdef DEBUG_SOF
        dev_vdbg(hsotg->dev, "--Start of Frame Interrupt--\n");
#endif

        hsotg->frame_number = dwc2_hcd_get_frame_number(hsotg);

        dwc2_track_missed_sofs(hsotg);

        /* Determine whether any periodic QHs should be executed */
        qh_entry = hsotg->periodic_sched_inactive.next;
        while (qh_entry != &hsotg->periodic_sched_inactive) {
                qh = list_entry(qh_entry, struct dwc2_qh, qh_list_entry);
                qh_entry = qh_entry->next;
                if (dwc2_frame_num_le(qh->next_active_frame,
                                      hsotg->frame_number)) {
                        dwc2_sch_vdbg(hsotg, "QH=%p ready fn=%04x, nxt=%04x\n",
                                      qh, hsotg->frame_number,
                                      qh->next_active_frame);

                        /*
                         * Move QH to the ready list to be executed next
                         * (micro)frame
                         */
                        list_move_tail(&qh->qh_list_entry,
                                       &hsotg->periodic_sched_ready);
                }
        }
        tr_type = dwc2_hcd_select_transactions(hsotg);
        if (tr_type != DWC2_TRANSACTION_NONE)
                dwc2_hcd_queue_transactions(hsotg, tr_type);
}

/*
 * Handles the Rx FIFO Level Interrupt, which indicates that there is
 * at least one packet in the Rx FIFO. The packets are moved from the FIFO to
 * memory if the DWC_otg controller is operating in Slave mode.
 */
static void dwc2_rx_fifo_level_intr(struct dwc2_hsotg *hsotg)
{
        u32 grxsts, chnum, bcnt, dpid, pktsts;
        struct dwc2_host_chan *chan;

        if (dbg_perio())
                dev_vdbg(hsotg->dev, "--RxFIFO Level Interrupt--\n");

        grxsts = dwc2_readl(hsotg, GRXSTSP);
        chnum = (grxsts & GRXSTS_HCHNUM_MASK) >> GRXSTS_HCHNUM_SHIFT;
        chan = hsotg->hc_ptr_array[chnum];
        if (!chan) {
                dev_err(hsotg->dev, "Unable to get corresponding channel\n");
                return;
        }

        bcnt = (grxsts & GRXSTS_BYTECNT_MASK) >> GRXSTS_BYTECNT_SHIFT;
        dpid = (grxsts & GRXSTS_DPID_MASK) >> GRXSTS_DPID_SHIFT;
        pktsts = (grxsts & GRXSTS_PKTSTS_MASK) >> GRXSTS_PKTSTS_SHIFT;

        /* Packet Status */
        if (dbg_perio()) {
                dev_vdbg(hsotg->dev, "    Ch num = %d\n", chnum);
                dev_vdbg(hsotg->dev, "    Count = %d\n", bcnt);
                dev_vdbg(hsotg->dev, "    DPID = %d, chan.dpid = %d\n", dpid,
                         chan->data_pid_start);
                dev_vdbg(hsotg->dev, "    PStatus = %d\n", pktsts);
        }

        switch (pktsts) {
        case GRXSTS_PKTSTS_HCHIN:
                /* Read the data into the host buffer */
                if (bcnt > 0) {
                        dwc2_read_packet(hsotg, chan->xfer_buf, bcnt);

                        /* Update the HC fields for the next packet received */
                        chan->xfer_count += bcnt;
                        chan->xfer_buf += bcnt;
                }
                break;
        case GRXSTS_PKTSTS_HCHIN_XFER_COMP:
        case GRXSTS_PKTSTS_DATATOGGLEERR:
        case GRXSTS_PKTSTS_HCHHALTED:
                /* Handled in interrupt, just ignore data */
                break;
        default:
                dev_err(hsotg->dev,
                        "RxFIFO Level Interrupt: Unknown status %d\n", pktsts);
                break;
        }
}

/*
 * This interrupt occurs when the non-periodic Tx FIFO is half-empty. More
 * data packets may be written to the FIFO for OUT transfers. More requests
 * may be written to the non-periodic request queue for IN transfers. This
 * interrupt is enabled only in Slave mode.
 */
static void dwc2_np_tx_fifo_empty_intr(struct dwc2_hsotg *hsotg)
{
        dev_vdbg(hsotg->dev, "--Non-Periodic TxFIFO Empty Interrupt--\n");
        dwc2_hcd_queue_transactions(hsotg, DWC2_TRANSACTION_NON_PERIODIC);
}

/*
 * This interrupt occurs when the periodic Tx FIFO is half-empty. More data
 * packets may be written to the FIFO for OUT transfers. More requests may be
 * written to the periodic request queue for IN transfers. This interrupt is
 * enabled only in Slave mode.
 */
static void dwc2_perio_tx_fifo_empty_intr(struct dwc2_hsotg *hsotg)
{
        if (dbg_perio())
                dev_vdbg(hsotg->dev, "--Periodic TxFIFO Empty Interrupt--\n");
        dwc2_hcd_queue_transactions(hsotg, DWC2_TRANSACTION_PERIODIC);
}

static void dwc2_hprt0_enable(struct dwc2_hsotg *hsotg, u32 hprt0,
                              u32 *hprt0_modify)
{
        struct dwc2_core_params *params = &hsotg->params;
        int do_reset = 0;
        u32 usbcfg;
        u32 prtspd;
        u32 hcfg;
        u32 fslspclksel;
        u32 hfir;

        dev_vdbg(hsotg->dev, "%s(%p)\n", __func__, hsotg);

        /* Every time when port enables calculate HFIR.FrInterval */
        hfir = dwc2_readl(hsotg, HFIR);
        hfir &= ~HFIR_FRINT_MASK;
        hfir |= dwc2_calc_frame_interval(hsotg) << HFIR_FRINT_SHIFT &
                HFIR_FRINT_MASK;
        dwc2_writel(hsotg, hfir, HFIR);

        /* Check if we need to adjust the PHY clock speed for low power */
        if (!params->host_support_fs_ls_low_power) {
                /* Port has been enabled, set the reset change flag */
                hsotg->flags.b.port_reset_change = 1;
                return;
        }

        usbcfg = dwc2_readl(hsotg, GUSBCFG);
        prtspd = (hprt0 & HPRT0_SPD_MASK) >> HPRT0_SPD_SHIFT;

        if (prtspd == HPRT0_SPD_LOW_SPEED || prtspd == HPRT0_SPD_FULL_SPEED) {
                /* Low power */
                if (!(usbcfg & GUSBCFG_PHY_LP_CLK_SEL)) {
                        /* Set PHY low power clock select for FS/LS devices */
                        usbcfg |= GUSBCFG_PHY_LP_CLK_SEL;
                        dwc2_writel(hsotg, usbcfg, GUSBCFG);
                        do_reset = 1;
                }

                hcfg = dwc2_readl(hsotg, HCFG);
                fslspclksel = (hcfg & HCFG_FSLSPCLKSEL_MASK) >>
                              HCFG_FSLSPCLKSEL_SHIFT;

                if (prtspd == HPRT0_SPD_LOW_SPEED &&
                    params->host_ls_low_power_phy_clk) {
                        /* 6 MHZ */
                        dev_vdbg(hsotg->dev,
                                 "FS_PHY programming HCFG to 6 MHz\n");
                        if (fslspclksel != HCFG_FSLSPCLKSEL_6_MHZ) {
                                fslspclksel = HCFG_FSLSPCLKSEL_6_MHZ;
                                hcfg &= ~HCFG_FSLSPCLKSEL_MASK;
                                hcfg |= fslspclksel << HCFG_FSLSPCLKSEL_SHIFT;
                                dwc2_writel(hsotg, hcfg, HCFG);
                                do_reset = 1;
                        }
                } else {
                        /* 48 MHZ */
                        dev_vdbg(hsotg->dev,
                                 "FS_PHY programming HCFG to 48 MHz\n");
                        if (fslspclksel != HCFG_FSLSPCLKSEL_48_MHZ) {
                                fslspclksel = HCFG_FSLSPCLKSEL_48_MHZ;
                                hcfg &= ~HCFG_FSLSPCLKSEL_MASK;
                                hcfg |= fslspclksel << HCFG_FSLSPCLKSEL_SHIFT;
                                dwc2_writel(hsotg, hcfg, HCFG);
                                do_reset = 1;
                        }
                }
        } else {
                /* Not low power */
                if (usbcfg & GUSBCFG_PHY_LP_CLK_SEL) {
                        usbcfg &= ~GUSBCFG_PHY_LP_CLK_SEL;
                        dwc2_writel(hsotg, usbcfg, GUSBCFG);
                        do_reset = 1;
                }
        }

        if (do_reset) {
                *hprt0_modify |= HPRT0_RST;
                dwc2_writel(hsotg, *hprt0_modify, HPRT0);
                queue_delayed_work(hsotg->wq_otg, &hsotg->reset_work,
                                   msecs_to_jiffies(60));
        } else {
                /* Port has been enabled, set the reset change flag */
                hsotg->flags.b.port_reset_change = 1;
        }
}

/*
 * There are multiple conditions that can cause a port interrupt. This function
 * determines which interrupt conditions have occurred and handles them
 * appropriately.
 */
static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
{
        u32 hprt0;
        u32 hprt0_modify;

        dev_vdbg(hsotg->dev, "--Port Interrupt--\n");

        hprt0 = dwc2_readl(hsotg, HPRT0);
        hprt0_modify = hprt0;

        /*
         * Clear appropriate bits in HPRT0 to clear the interrupt bit in
         * GINTSTS
         */
        hprt0_modify &= ~(HPRT0_ENA | HPRT0_CONNDET | HPRT0_ENACHG |
                          HPRT0_OVRCURRCHG);

        /*
         * Port Connect Detected
         * Set flag and clear if detected
         */
        if (hprt0 & HPRT0_CONNDET) {
                dwc2_writel(hsotg, hprt0_modify | HPRT0_CONNDET, HPRT0);

                dev_vdbg(hsotg->dev,
                         "--Port Interrupt HPRT0=0x%08x Port Connect Detected--\n",
                         hprt0);
                dwc2_hcd_connect(hsotg);

                /*
                 * The Hub driver asserts a reset when it sees port connect
                 * status change flag
                 */
        }

        /*
         * Port Enable Changed
         * Clear if detected - Set internal flag if disabled
         */
        if (hprt0 & HPRT0_ENACHG) {
                dwc2_writel(hsotg, hprt0_modify | HPRT0_ENACHG, HPRT0);
                dev_vdbg(hsotg->dev,
                         "  --Port Interrupt HPRT0=0x%08x Port Enable Changed (now %d)--\n",
                         hprt0, !!(hprt0 & HPRT0_ENA));
                if (hprt0 & HPRT0_ENA) {
                        hsotg->new_connection = true;
                        dwc2_hprt0_enable(hsotg, hprt0, &hprt0_modify);
                } else {
                        hsotg->flags.b.port_enable_change = 1;
                        if (hsotg->params.dma_desc_fs_enable) {
                                u32 hcfg;

                                hsotg->params.dma_desc_enable = false;
                                hsotg->new_connection = false;
                                hcfg = dwc2_readl(hsotg, HCFG);
                                hcfg &= ~HCFG_DESCDMA;
                                dwc2_writel(hsotg, hcfg, HCFG);
                        }
                }
        }

        /* Overcurrent Change Interrupt */
        if (hprt0 & HPRT0_OVRCURRCHG) {
                dwc2_writel(hsotg, hprt0_modify | HPRT0_OVRCURRCHG,
                            HPRT0);
                dev_vdbg(hsotg->dev,
                         "  --Port Interrupt HPRT0=0x%08x Port Overcurrent Changed--\n",
                         hprt0);
                hsotg->flags.b.port_over_current_change = 1;
        }
}

/*
 * Gets the actual length of a transfer after the transfer halts. halt_status
 * holds the reason for the halt.
 *
 * For IN transfers where halt_status is DWC2_HC_XFER_COMPLETE, *short_read
 * is set to 1 upon return if less than the requested number of bytes were
 * transferred. short_read may also be NULL on entry, in which case it remains
 * unchanged.
 */
static u32 dwc2_get_actual_xfer_length(struct dwc2_hsotg *hsotg,
                                       struct dwc2_host_chan *chan, int chnum,
                                       struct dwc2_qtd *qtd,
                                       enum dwc2_halt_status halt_status,
                                       int *short_read)
{
        u32 hctsiz, count, length;

        hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));

        if (halt_status == DWC2_HC_XFER_COMPLETE) {
                if (chan->ep_is_in) {
                        count = (hctsiz & TSIZ_XFERSIZE_MASK) >>
                                TSIZ_XFERSIZE_SHIFT;
                        length = chan->xfer_len - count;
                        if (short_read)
                                *short_read = (count != 0);
                } else if (chan->qh->do_split) {
                        length = qtd->ssplit_out_xfer_count;
                } else {
                        length = chan->xfer_len;
                }
        } else {
                /*
                 * Must use the hctsiz.pktcnt field to determine how much data
                 * has been transferred. This field reflects the number of
                 * packets that have been transferred via the USB. This is
                 * always an integral number of packets if the transfer was
                 * halted before its normal completion. (Can't use the
                 * hctsiz.xfersize field because that reflects the number of
                 * bytes transferred via the AHB, not the USB).
                 */
                count = (hctsiz & TSIZ_PKTCNT_MASK) >> TSIZ_PKTCNT_SHIFT;
                length = (chan->start_pkt_count - count) * chan->max_packet;
        }

        return length;
}

/**
 * dwc2_update_urb_state() - Updates the state of the URB after a Transfer
 * Complete interrupt on the host channel. Updates the actual_length field
 * of the URB based on the number of bytes transferred via the host channel.
 * Sets the URB status if the data transfer is finished.
 *
 * @hsotg: Programming view of the DWC_otg controller
 * @chan: Programming view of host channel
 * @chnum: Channel number
 * @urb: Processing URB
 * @qtd: Queue transfer descriptor
 *
 * Return: 1 if the data transfer specified by the URB is completely finished,
 * 0 otherwise
 */
static int dwc2_update_urb_state(struct dwc2_hsotg *hsotg,
                                 struct dwc2_host_chan *chan, int chnum,
                                 struct dwc2_hcd_urb *urb,
                                 struct dwc2_qtd *qtd)
{
        u32 hctsiz;
        int xfer_done = 0;
        int short_read = 0;
        int xfer_length = dwc2_get_actual_xfer_length(hsotg, chan, chnum, qtd,
                                                      DWC2_HC_XFER_COMPLETE,
                                                      &short_read);

        if (urb->actual_length + xfer_length > urb->length) {
                dev_dbg(hsotg->dev, "%s(): trimming xfer length\n", __func__);
                xfer_length = urb->length - urb->actual_length;
        }

        dev_vdbg(hsotg->dev, "urb->actual_length=%d xfer_length=%d\n",
                 urb->actual_length, xfer_length);
        urb->actual_length += xfer_length;

        if (xfer_length && chan->ep_type == USB_ENDPOINT_XFER_BULK &&
            (urb->flags & URB_SEND_ZERO_PACKET) &&
            urb->actual_length >= urb->length &&
            !(urb->length % chan->max_packet)) {
                xfer_done = 0;
        } else if (short_read || urb->actual_length >= urb->length) {
                xfer_done = 1;
                urb->status = 0;
        }

        hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));
        dev_vdbg(hsotg->dev, "DWC_otg: %s: %s, channel %d\n",
                 __func__, (chan->ep_is_in ? "IN" : "OUT"), chnum);
        dev_vdbg(hsotg->dev, "  chan->xfer_len %d\n", chan->xfer_len);
        dev_vdbg(hsotg->dev, "  hctsiz.xfersize %d\n",
                 (hctsiz & TSIZ_XFERSIZE_MASK) >> TSIZ_XFERSIZE_SHIFT);
        dev_vdbg(hsotg->dev, "  urb->transfer_buffer_length %d\n", urb->length);
        dev_vdbg(hsotg->dev, "  urb->actual_length %d\n", urb->actual_length);
        dev_vdbg(hsotg->dev, "  short_read %d, xfer_done %d\n", short_read,
                 xfer_done);

        return xfer_done;
}

/*
 * Save the starting data toggle for the next transfer. The data toggle is
 * saved in the QH for non-control transfers and it's saved in the QTD for
 * control transfers.
 */
void dwc2_hcd_save_data_toggle(struct dwc2_hsotg *hsotg,
                               struct dwc2_host_chan *chan, int chnum,
                               struct dwc2_qtd *qtd)
{
        u32 hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));
        u32 pid = (hctsiz & TSIZ_SC_MC_PID_MASK) >> TSIZ_SC_MC_PID_SHIFT;

        if (chan->ep_type != USB_ENDPOINT_XFER_CONTROL) {
                if (WARN(!chan || !chan->qh,
                         "chan->qh must be specified for non-control eps\n"))
                        return;

                if (pid == TSIZ_SC_MC_PID_DATA0)
                        chan->qh->data_toggle = DWC2_HC_PID_DATA0;
                else
                        chan->qh->data_toggle = DWC2_HC_PID_DATA1;
        } else {
                if (WARN(!qtd,
                         "qtd must be specified for control eps\n"))
                        return;

                if (pid == TSIZ_SC_MC_PID_DATA0)
                        qtd->data_toggle = DWC2_HC_PID_DATA0;
                else
                        qtd->data_toggle = DWC2_HC_PID_DATA1;
        }
}

/**
 * dwc2_update_isoc_urb_state() - Updates the state of an Isochronous URB when
 * the transfer is stopped for any reason. The fields of the current entry in
 * the frame descriptor array are set based on the transfer state and the input
 * halt_status. Completes the Isochronous URB if all the URB frames have been
 * completed.
 *
 * @hsotg: Programming view of the DWC_otg controller
 * @chan: Programming view of host channel
 * @chnum: Channel number
 * @halt_status: Reason for halting a host channel
 * @qtd: Queue transfer descriptor
 *
 * Return: DWC2_HC_XFER_COMPLETE if there are more frames remaining to be
 * transferred in the URB. Otherwise return DWC2_HC_XFER_URB_COMPLETE.
 */
static enum dwc2_halt_status dwc2_update_isoc_urb_state(
                struct dwc2_hsotg *hsotg, struct dwc2_host_chan *chan,
                int chnum, struct dwc2_qtd *qtd,
                enum dwc2_halt_status halt_status)
{
        struct dwc2_hcd_iso_packet_desc *frame_desc;
        struct dwc2_hcd_urb *urb = qtd->urb;

        if (!urb)
                return DWC2_HC_XFER_NO_HALT_STATUS;

        frame_desc = &urb->iso_descs[qtd->isoc_frame_index];

        switch (halt_status) {
        case DWC2_HC_XFER_COMPLETE:
                frame_desc->status = 0;
                frame_desc->actual_length = dwc2_get_actual_xfer_length(hsotg,
                                        chan, chnum, qtd, halt_status, NULL);
                break;
        case DWC2_HC_XFER_FRAME_OVERRUN:
                urb->error_count++;
                if (chan->ep_is_in)
                        frame_desc->status = -ENOSR;
                else
                        frame_desc->status = -ECOMM;
                frame_desc->actual_length = 0;
                break;
        case DWC2_HC_XFER_BABBLE_ERR:
                urb->error_count++;
                frame_desc->status = -EOVERFLOW;
                /* Don't need to update actual_length in this case */
                break;
        case DWC2_HC_XFER_XACT_ERR:
                urb->error_count++;
                frame_desc->status = -EPROTO;
                frame_desc->actual_length = dwc2_get_actual_xfer_length(hsotg,
                                        chan, chnum, qtd, halt_status, NULL);

                /* Skip whole frame */
                if (chan->qh->do_split &&
                    chan->ep_type == USB_ENDPOINT_XFER_ISOC && chan->ep_is_in &&
                    hsotg->params.host_dma) {
                        qtd->complete_split = 0;
                        qtd->isoc_split_offset = 0;
                }

                break;
        default:
                dev_err(hsotg->dev, "Unhandled halt_status (%d)\n",
                        halt_status);
                break;
        }

        if (++qtd->isoc_frame_index == urb->packet_count) {
                /*
                 * urb->status is not used for isoc transfers. The individual
                 * frame_desc statuses are used instead.
                 */
                dwc2_host_complete(hsotg, qtd, 0);
                halt_status = DWC2_HC_XFER_URB_COMPLETE;
        } else {
                halt_status = DWC2_HC_XFER_COMPLETE;
        }

        return halt_status;
}

/*
 * Frees the first QTD in the QH's list if free_qtd is 1. For non-periodic
 * QHs, removes the QH from the active non-periodic schedule. If any QTDs are
 * still linked to the QH, the QH is added to the end of the inactive
 * non-periodic schedule. For periodic QHs, removes the QH from the periodic
 * schedule if no more QTDs are linked to the QH.
 */
static void dwc2_deactivate_qh(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
                               int free_qtd)
{
        int continue_split = 0;
        struct dwc2_qtd *qtd;

        if (dbg_qh(qh))
                dev_vdbg(hsotg->dev, "  %s(%p,%p,%d)\n", __func__,
                         hsotg, qh, free_qtd);

        if (list_empty(&qh->qtd_list)) {
                dev_dbg(hsotg->dev, "## QTD list empty ##\n");
                goto no_qtd;
        }

        qtd = list_first_entry(&qh->qtd_list, struct dwc2_qtd, qtd_list_entry);

        if (qtd->complete_split)
                continue_split = 1;
        else if (qtd->isoc_split_pos == DWC2_HCSPLT_XACTPOS_MID ||
                 qtd->isoc_split_pos == DWC2_HCSPLT_XACTPOS_END)
                continue_split = 1;

        if (free_qtd) {
                dwc2_hcd_qtd_unlink_and_free(hsotg, qtd, qh);
                continue_split = 0;
        }

no_qtd:
        qh->channel = NULL;
        dwc2_hcd_qh_deactivate(hsotg, qh, continue_split);
}

/**
 * dwc2_release_channel() - Releases a host channel for use by other transfers
 *
 * @hsotg:       The HCD state structure
 * @chan:        The host channel to release
 * @qtd:         The QTD associated with the host channel. This QTD may be
 *               freed if the transfer is complete or an error has occurred.
 * @halt_status: Reason the channel is being released. This status
 *               determines the actions taken by this function.
 *
 * Also attempts to select and queue more transactions since at least one host
 * channel is available.
 */
static void dwc2_release_channel(struct dwc2_hsotg *hsotg,
                                 struct dwc2_host_chan *chan,
                                 struct dwc2_qtd *qtd,
                                 enum dwc2_halt_status halt_status)
{
        enum dwc2_transaction_type tr_type;
        u32 haintmsk;
        int free_qtd = 0;

        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev, "  %s: channel %d, halt_status %d\n",
                         __func__, chan->hc_num, halt_status);

        switch (halt_status) {
        case DWC2_HC_XFER_URB_COMPLETE:
                free_qtd = 1;
                break;
        case DWC2_HC_XFER_AHB_ERR:
        case DWC2_HC_XFER_STALL:
        case DWC2_HC_XFER_BABBLE_ERR:
                free_qtd = 1;
                break;
        case DWC2_HC_XFER_XACT_ERR:
                if (qtd && qtd->error_count >= 3) {
                        dev_vdbg(hsotg->dev,
                                 "  Complete URB with transaction error\n");
                        free_qtd = 1;
                        dwc2_host_complete(hsotg, qtd, -EPROTO);
                }
                break;
        case DWC2_HC_XFER_URB_DEQUEUE:
                /*
                 * The QTD has already been removed and the QH has been
                 * deactivated. Don't want to do anything except release the
                 * host channel and try to queue more transfers.
                 */
                goto cleanup;
        case DWC2_HC_XFER_PERIODIC_INCOMPLETE:
                dev_vdbg(hsotg->dev, "  Complete URB with I/O error\n");
                free_qtd = 1;
                dwc2_host_complete(hsotg, qtd, -EIO);
                break;
        case DWC2_HC_XFER_NO_HALT_STATUS:
        default:
                break;
        }

        dwc2_deactivate_qh(hsotg, chan->qh, free_qtd);

cleanup:
        /*
         * Release the host channel for use by other transfers. The cleanup
         * function clears the channel interrupt enables and conditions, so
         * there's no need to clear the Channel Halted interrupt separately.
         */
        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);

        if (hsotg->params.uframe_sched) {
                hsotg->available_host_channels++;
        } else {
                switch (chan->ep_type) {
                case USB_ENDPOINT_XFER_CONTROL:
                case USB_ENDPOINT_XFER_BULK:
                        hsotg->non_periodic_channels--;
                        break;
                default:
                        /*
                         * Don't release reservations for periodic channels
                         * here. That's done when a periodic transfer is
                         * descheduled (i.e. when the QH is removed from the
                         * periodic schedule).
                         */
                        break;
                }
        }

        haintmsk = dwc2_readl(hsotg, HAINTMSK);
        haintmsk &= ~(1 << chan->hc_num);
        dwc2_writel(hsotg, haintmsk, HAINTMSK);

        /* Try to queue more transfers now that there's a free channel */
        tr_type = dwc2_hcd_select_transactions(hsotg);
        if (tr_type != DWC2_TRANSACTION_NONE)
                dwc2_hcd_queue_transactions(hsotg, tr_type);
}

/*
 * Halts a host channel. If the channel cannot be halted immediately because
 * the request queue is full, this function ensures that the FIFO empty
 * interrupt for the appropriate queue is enabled so that the halt request can
 * be queued when there is space in the request queue.
 *
 * This function may also be called in DMA mode. In that case, the channel is
 * simply released since the core always halts the channel automatically in
 * DMA mode.
 */
static void dwc2_halt_channel(struct dwc2_hsotg *hsotg,
                              struct dwc2_host_chan *chan, struct dwc2_qtd *qtd,
                              enum dwc2_halt_status halt_status)
{
        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev, "%s()\n", __func__);

        if (hsotg->params.host_dma) {
                if (dbg_hc(chan))
                        dev_vdbg(hsotg->dev, "DMA enabled\n");
                dwc2_release_channel(hsotg, chan, qtd, halt_status);
                return;
        }

        /* Slave mode processing */
        dwc2_hc_halt(hsotg, chan, halt_status);

        if (chan->halt_on_queue) {
                u32 gintmsk;

                dev_vdbg(hsotg->dev, "Halt on queue\n");
                if (chan->ep_type == USB_ENDPOINT_XFER_CONTROL ||
                    chan->ep_type == USB_ENDPOINT_XFER_BULK) {
                        dev_vdbg(hsotg->dev, "control/bulk\n");
                        /*
                         * Make sure the Non-periodic Tx FIFO empty interrupt
                         * is enabled so that the non-periodic schedule will
                         * be processed
                         */
                        gintmsk = dwc2_readl(hsotg, GINTMSK);
                        gintmsk |= GINTSTS_NPTXFEMP;
                        dwc2_writel(hsotg, gintmsk, GINTMSK);
                } else {
                        dev_vdbg(hsotg->dev, "isoc/intr\n");
                        /*
                         * Move the QH from the periodic queued schedule to
                         * the periodic assigned schedule. This allows the
                         * halt to be queued when the periodic schedule is
                         * processed.
                         */
                        list_move_tail(&chan->qh->qh_list_entry,
                                       &hsotg->periodic_sched_assigned);

                        /*
                         * Make sure the Periodic Tx FIFO Empty interrupt is
                         * enabled so that the periodic schedule will be
                         * processed
                         */
                        gintmsk = dwc2_readl(hsotg, GINTMSK);
                        gintmsk |= GINTSTS_PTXFEMP;
                        dwc2_writel(hsotg, gintmsk, GINTMSK);
                }
        }
}

/*
 * Performs common cleanup for non-periodic transfers after a Transfer
 * Complete interrupt. This function should be called after any endpoint type
 * specific handling is finished to release the host channel.
 */
static void dwc2_complete_non_periodic_xfer(struct dwc2_hsotg *hsotg,
                                            struct dwc2_host_chan *chan,
                                            int chnum, struct dwc2_qtd *qtd,
                                            enum dwc2_halt_status halt_status)
{
        dev_vdbg(hsotg->dev, "%s()\n", __func__);

        qtd->error_count = 0;

        if (chan->hcint & HCINTMSK_NYET) {
                /*
                 * Got a NYET on the last transaction of the transfer. This
                 * means that the endpoint should be in the PING state at the
                 * beginning of the next transfer.
                 */
                dev_vdbg(hsotg->dev, "got NYET\n");
                chan->qh->ping_state = 1;
        }

        /*
         * Always halt and release the host channel to make it available for
         * more transfers. There may still be more phases for a control
         * transfer or more data packets for a bulk transfer at this point,
         * but the host channel is still halted. A channel will be reassigned
         * to the transfer when the non-periodic schedule is processed after
         * the channel is released. This allows transactions to be queued
         * properly via dwc2_hcd_queue_transactions, which also enables the
         * Tx FIFO Empty interrupt if necessary.
         */
        if (chan->ep_is_in) {
                /*
                 * IN transfers in Slave mode require an explicit disable to
                 * halt the channel. (In DMA mode, this call simply releases
                 * the channel.)
                 */
                dwc2_halt_channel(hsotg, chan, qtd, halt_status);
        } else {
                /*
                 * The channel is automatically disabled by the core for OUT
                 * transfers in Slave mode
                 */
                dwc2_release_channel(hsotg, chan, qtd, halt_status);
        }
}

/*
 * Performs common cleanup for periodic transfers after a Transfer Complete
 * interrupt. This function should be called after any endpoint type specific
 * handling is finished to release the host channel.
 */
static void dwc2_complete_periodic_xfer(struct dwc2_hsotg *hsotg,
                                        struct dwc2_host_chan *chan, int chnum,
                                        struct dwc2_qtd *qtd,
                                        enum dwc2_halt_status halt_status)
{
        u32 hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));

        qtd->error_count = 0;

        if (!chan->ep_is_in || (hctsiz & TSIZ_PKTCNT_MASK) == 0)
                /* Core halts channel in these cases */
                dwc2_release_channel(hsotg, chan, qtd, halt_status);
        else
                /* Flush any outstanding requests from the Tx queue */
                dwc2_halt_channel(hsotg, chan, qtd, halt_status);
}

static int dwc2_xfercomp_isoc_split_in(struct dwc2_hsotg *hsotg,
                                       struct dwc2_host_chan *chan, int chnum,
                                       struct dwc2_qtd *qtd)
{
        struct dwc2_hcd_iso_packet_desc *frame_desc;
        u32 len;
        u32 hctsiz;
        u32 pid;

        if (!qtd->urb)
                return 0;

        frame_desc = &qtd->urb->iso_descs[qtd->isoc_frame_index];
        len = dwc2_get_actual_xfer_length(hsotg, chan, chnum, qtd,
                                          DWC2_HC_XFER_COMPLETE, NULL);
        if (!len && !qtd->isoc_split_offset) {
                qtd->complete_split = 0;
                return 0;
        }

        frame_desc->actual_length += len;

        if (chan->align_buf) {
                dev_vdbg(hsotg->dev, "non-aligned buffer\n");
                dma_unmap_single(hsotg->dev, chan->qh->dw_align_buf_dma,
                                 DWC2_KMEM_UNALIGNED_BUF_SIZE, DMA_FROM_DEVICE);
                memcpy(qtd->urb->buf + (chan->xfer_dma - qtd->urb->dma),
                       chan->qh->dw_align_buf, len);
        }

        qtd->isoc_split_offset += len;

        hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));
        pid = (hctsiz & TSIZ_SC_MC_PID_MASK) >> TSIZ_SC_MC_PID_SHIFT;

        if (frame_desc->actual_length >= frame_desc->length || pid == 0) {
                frame_desc->status = 0;
                qtd->isoc_frame_index++;
                qtd->complete_split = 0;
                qtd->isoc_split_offset = 0;
        }

        if (qtd->isoc_frame_index == qtd->urb->packet_count) {
                dwc2_host_complete(hsotg, qtd, 0);
                dwc2_release_channel(hsotg, chan, qtd,
                                     DWC2_HC_XFER_URB_COMPLETE);
        } else {
                dwc2_release_channel(hsotg, chan, qtd,
                                     DWC2_HC_XFER_NO_HALT_STATUS);
        }

        return 1;       /* Indicates that channel released */
}

/*
 * Handles a host channel Transfer Complete interrupt. This handler may be
 * called in either DMA mode or Slave mode.
 */
static void dwc2_hc_xfercomp_intr(struct dwc2_hsotg *hsotg,
                                  struct dwc2_host_chan *chan, int chnum,
                                  struct dwc2_qtd *qtd)
{
        struct dwc2_hcd_urb *urb = qtd->urb;
        enum dwc2_halt_status halt_status = DWC2_HC_XFER_COMPLETE;
        int pipe_type;
        int urb_xfer_done;

        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev,
                         "--Host Channel %d Interrupt: Transfer Complete--\n",
                         chnum);

        if (!urb)
                goto handle_xfercomp_done;

        pipe_type = dwc2_hcd_get_pipe_type(&urb->pipe_info);

        if (hsotg->params.dma_desc_enable) {
                dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum, halt_status);
                if (pipe_type == USB_ENDPOINT_XFER_ISOC)
                        /* Do not disable the interrupt, just clear it */
                        return;
                goto handle_xfercomp_done;
        }

        /* Handle xfer complete on CSPLIT */
        if (chan->qh->do_split) {
                if (chan->ep_type == USB_ENDPOINT_XFER_ISOC && chan->ep_is_in &&
                    hsotg->params.host_dma) {
                        if (qtd->complete_split &&
                            dwc2_xfercomp_isoc_split_in(hsotg, chan, chnum,
                                                        qtd))
                                goto handle_xfercomp_done;
                } else {
                        qtd->complete_split = 0;
                }
        }

        /* Update the QTD and URB states */
        switch (pipe_type) {
        case 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");
                        halt_status = DWC2_HC_XFER_COMPLETE;
                        break;
                case DWC2_CONTROL_DATA:
                        urb_xfer_done = dwc2_update_urb_state(hsotg, chan,
                                                              chnum, urb, qtd);
                        if (urb_xfer_done) {
                                qtd->control_phase = DWC2_CONTROL_STATUS;
                                dev_vdbg(hsotg->dev,
                                         "  Control data transfer done\n");
                        } else {
                                dwc2_hcd_save_data_toggle(hsotg, chan, chnum,
                                                          qtd);
                        }
                        halt_status = DWC2_HC_XFER_COMPLETE;
                        break;
                case DWC2_CONTROL_STATUS:
                        dev_vdbg(hsotg->dev, "  Control transfer complete\n");
                        if (urb->status == -EINPROGRESS)
                                urb->status = 0;
                        dwc2_host_complete(hsotg, qtd, urb->status);
                        halt_status = DWC2_HC_XFER_URB_COMPLETE;
                        break;
                }

                dwc2_complete_non_periodic_xfer(hsotg, chan, chnum, qtd,
                                                halt_status);
                break;
        case USB_ENDPOINT_XFER_BULK:
                dev_vdbg(hsotg->dev, "  Bulk transfer complete\n");
                urb_xfer_done = dwc2_update_urb_state(hsotg, chan, chnum, urb,
                                                      qtd);
                if (urb_xfer_done) {
                        dwc2_host_complete(hsotg, qtd, urb->status);
                        halt_status = DWC2_HC_XFER_URB_COMPLETE;
                } else {
                        halt_status = DWC2_HC_XFER_COMPLETE;
                }

                dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);
                dwc2_complete_non_periodic_xfer(hsotg, chan, chnum, qtd,
                                                halt_status);
                break;
        case USB_ENDPOINT_XFER_INT:
                dev_vdbg(hsotg->dev, "  Interrupt transfer complete\n");
                urb_xfer_done = dwc2_update_urb_state(hsotg, chan, chnum, urb,
                                                      qtd);

                /*
                 * Interrupt URB is done on the first transfer complete
                 * interrupt
                 */
                if (urb_xfer_done) {
                        dwc2_host_complete(hsotg, qtd, urb->status);
                        halt_status = DWC2_HC_XFER_URB_COMPLETE;
                } else {
                        halt_status = DWC2_HC_XFER_COMPLETE;
                }

                dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);
                dwc2_complete_periodic_xfer(hsotg, chan, chnum, qtd,
                                            halt_status);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                if (dbg_perio())
                        dev_vdbg(hsotg->dev, "  Isochronous transfer complete\n");
                if (qtd->isoc_split_pos == DWC2_HCSPLT_XACTPOS_ALL)
                        halt_status = dwc2_update_isoc_urb_state(hsotg, chan,
                                                        chnum, qtd,
                                                        DWC2_HC_XFER_COMPLETE);
                dwc2_complete_periodic_xfer(hsotg, chan, chnum, qtd,
                                            halt_status);
                break;
        }

handle_xfercomp_done:
        disable_hc_int(hsotg, chnum, HCINTMSK_XFERCOMPL);
}

/*
 * Handles a host channel STALL interrupt. This handler may be called in
 * either DMA mode or Slave mode.
 */
static void dwc2_hc_stall_intr(struct dwc2_hsotg *hsotg,
                               struct dwc2_host_chan *chan, int chnum,
                               struct dwc2_qtd *qtd)
{
        struct dwc2_hcd_urb *urb = qtd->urb;
        int pipe_type;

        dev_dbg(hsotg->dev, "--Host Channel %d Interrupt: STALL Received--\n",
                chnum);

        if (hsotg->params.dma_desc_enable) {
                dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum,
                                            DWC2_HC_XFER_STALL);
                goto handle_stall_done;
        }

        if (!urb)
                goto handle_stall_halt;

        pipe_type = dwc2_hcd_get_pipe_type(&urb->pipe_info);

        if (pipe_type == USB_ENDPOINT_XFER_CONTROL)
                dwc2_host_complete(hsotg, qtd, -EPIPE);

        if (pipe_type == USB_ENDPOINT_XFER_BULK ||
            pipe_type == USB_ENDPOINT_XFER_INT) {
                dwc2_host_complete(hsotg, qtd, -EPIPE);
                /*
                 * USB protocol requires resetting the data toggle for bulk
                 * and interrupt endpoints when a CLEAR_FEATURE(ENDPOINT_HALT)
                 * setup command is issued to the endpoint. Anticipate the
                 * CLEAR_FEATURE command since a STALL has occurred and reset
                 * the data toggle now.
                 */
                chan->qh->data_toggle = 0;
        }

handle_stall_halt:
        dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_STALL);

handle_stall_done:
        disable_hc_int(hsotg, chnum, HCINTMSK_STALL);
}

/*
 * Updates the state of the URB when a transfer has been stopped due to an
 * abnormal condition before the transfer completes. Modifies the
 * actual_length field of the URB to reflect the number of bytes that have
 * actually been transferred via the host channel.
 */
static void dwc2_update_urb_state_abn(struct dwc2_hsotg *hsotg,
                                      struct dwc2_host_chan *chan, int chnum,
                                      struct dwc2_hcd_urb *urb,
                                      struct dwc2_qtd *qtd,
                                      enum dwc2_halt_status halt_status)
{
        u32 xfer_length = dwc2_get_actual_xfer_length(hsotg, chan, chnum,
                                                      qtd, halt_status, NULL);
        u32 hctsiz;

        if (urb->actual_length + xfer_length > urb->length) {
                dev_warn(hsotg->dev, "%s(): trimming xfer length\n", __func__);
                xfer_length = urb->length - urb->actual_length;
        }

        urb->actual_length += xfer_length;

        hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));
        dev_vdbg(hsotg->dev, "DWC_otg: %s: %s, channel %d\n",
                 __func__, (chan->ep_is_in ? "IN" : "OUT"), chnum);
        dev_vdbg(hsotg->dev, "  chan->start_pkt_count %d\n",
                 chan->start_pkt_count);
        dev_vdbg(hsotg->dev, "  hctsiz.pktcnt %d\n",
                 (hctsiz & TSIZ_PKTCNT_MASK) >> TSIZ_PKTCNT_SHIFT);
        dev_vdbg(hsotg->dev, "  chan->max_packet %d\n", chan->max_packet);
        dev_vdbg(hsotg->dev, "  bytes_transferred %d\n",
                 xfer_length);
        dev_vdbg(hsotg->dev, "  urb->actual_length %d\n",
                 urb->actual_length);
        dev_vdbg(hsotg->dev, "  urb->transfer_buffer_length %d\n",
                 urb->length);
}

/*
 * Handles a host channel NAK interrupt. This handler may be called in either
 * DMA mode or Slave mode.
 */
static void dwc2_hc_nak_intr(struct dwc2_hsotg *hsotg,
                             struct dwc2_host_chan *chan, int chnum,
                             struct dwc2_qtd *qtd)
{
        if (!qtd) {
                dev_dbg(hsotg->dev, "%s: qtd is NULL\n", __func__);
                return;
        }

        if (!qtd->urb) {
                dev_dbg(hsotg->dev, "%s: qtd->urb is NULL\n", __func__);
                return;
        }

        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev, "--Host Channel %d Interrupt: NAK Received--\n",
                         chnum);

        /*
         * Handle NAK for IN/OUT SSPLIT/CSPLIT transfers, bulk, control, and
         * interrupt. Re-start the SSPLIT transfer.
         *
         * Normally for non-periodic transfers we'll retry right away, but to
         * avoid interrupt storms we'll wait before retrying if we've got
         * several NAKs. If we didn't do this we'd retry directly from the
         * interrupt handler and could end up quickly getting another
         * interrupt (another NAK), which we'd retry. Note that we do not
         * delay retries for IN parts of control requests, as those are expected
         * to complete fairly quickly, and if we delay them we risk confusing
         * the device and cause it issue STALL.
         *
         * Note that in DMA mode software only gets involved to re-send NAKed
         * transfers for split transactions, so we only need to apply this
         * delaying logic when handling splits. In non-DMA mode presumably we
         * might want a similar delay if someone can demonstrate this problem
         * affects that code path too.
         */
        if (chan->do_split) {
                if (chan->complete_split)
                        qtd->error_count = 0;
                qtd->complete_split = 0;
                qtd->num_naks++;
                qtd->qh->want_wait = qtd->num_naks >= DWC2_NAKS_BEFORE_DELAY &&
                                !(chan->ep_type == USB_ENDPOINT_XFER_CONTROL &&
                                  chan->ep_is_in);
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NAK);
                goto handle_nak_done;
        }

        switch (dwc2_hcd_get_pipe_type(&qtd->urb->pipe_info)) {
        case USB_ENDPOINT_XFER_CONTROL:
        case USB_ENDPOINT_XFER_BULK:
                if (hsotg->params.host_dma && chan->ep_is_in) {
                        /*
                         * NAK interrupts are enabled on bulk/control IN
                         * transfers in DMA mode for the sole purpose of
                         * resetting the error count after a transaction error
                         * occurs. The core will continue transferring data.
                         */
                        qtd->error_count = 0;
                        break;
                }

                /*
                 * NAK interrupts normally occur during OUT transfers in DMA
                 * or Slave mode. For IN transfers, more requests will be
                 * queued as request queue space is available.
                 */
                qtd->error_count = 0;

                if (!chan->qh->ping_state) {
                        dwc2_update_urb_state_abn(hsotg, chan, chnum, qtd->urb,
                                                  qtd, DWC2_HC_XFER_NAK);
                        dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);

                        if (chan->speed == USB_SPEED_HIGH)
                                chan->qh->ping_state = 1;
                }

                /*
                 * Halt the channel so the transfer can be re-started from
                 * the appropriate point or the PING protocol will
                 * start/continue
                 */
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NAK);
                break;
        case USB_ENDPOINT_XFER_INT:
                qtd->error_count = 0;
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NAK);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                /* Should never get called for isochronous transfers */
                dev_err(hsotg->dev, "NACK interrupt for ISOC transfer\n");
                break;
        }

handle_nak_done:
        disable_hc_int(hsotg, chnum, HCINTMSK_NAK);
}

/*
 * Handles a host channel ACK interrupt. This interrupt is enabled when
 * performing the PING protocol in Slave mode, when errors occur during
 * either Slave mode or DMA mode, and during Start Split transactions.
 */
static void dwc2_hc_ack_intr(struct dwc2_hsotg *hsotg,
                             struct dwc2_host_chan *chan, int chnum,
                             struct dwc2_qtd *qtd)
{
        struct dwc2_hcd_iso_packet_desc *frame_desc;

        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev, "--Host Channel %d Interrupt: ACK Received--\n",
                         chnum);

        if (chan->do_split) {
                /* Handle ACK on SSPLIT. ACK should not occur in CSPLIT. */
                if (!chan->ep_is_in &&
                    chan->data_pid_start != DWC2_HC_PID_SETUP)
                        qtd->ssplit_out_xfer_count = chan->xfer_len;

                if (chan->ep_type != USB_ENDPOINT_XFER_ISOC || chan->ep_is_in) {
                        qtd->complete_split = 1;
                        dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_ACK);
                } else {
                        /* ISOC OUT */
                        switch (chan->xact_pos) {
                        case DWC2_HCSPLT_XACTPOS_ALL:
                                break;
                        case DWC2_HCSPLT_XACTPOS_END:
                                qtd->isoc_split_pos = DWC2_HCSPLT_XACTPOS_ALL;
                                qtd->isoc_split_offset = 0;
                                break;
                        case DWC2_HCSPLT_XACTPOS_BEGIN:
                        case DWC2_HCSPLT_XACTPOS_MID:
                                /*
                                 * For BEGIN or MID, calculate the length for
                                 * the next microframe to determine the correct
                                 * SSPLIT token, either MID or END
                                 */
                                frame_desc = &qtd->urb->iso_descs[
                                                qtd->isoc_frame_index];
                                qtd->isoc_split_offset += 188;

                                if (frame_desc->length - qtd->isoc_split_offset
                                                        <= 188)
                                        qtd->isoc_split_pos =
                                                        DWC2_HCSPLT_XACTPOS_END;
                                else
                                        qtd->isoc_split_pos =
                                                        DWC2_HCSPLT_XACTPOS_MID;
                                break;
                        }
                }
        } else {
                qtd->error_count = 0;

                if (chan->qh->ping_state) {
                        chan->qh->ping_state = 0;
                        /*
                         * Halt the channel so the transfer can be re-started
                         * from the appropriate point. This only happens in
                         * Slave mode. In DMA mode, the ping_state is cleared
                         * when the transfer is started because the core
                         * automatically executes the PING, then the transfer.
                         */
                        dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_ACK);
                }
        }

        /*
         * If the ACK occurred when _not_ in the PING state, let the channel
         * continue transferring data after clearing the error count
         */
        disable_hc_int(hsotg, chnum, HCINTMSK_ACK);
}

/*
 * Handles a host channel NYET interrupt. This interrupt should only occur on
 * Bulk and Control OUT endpoints and for complete split transactions. If a
 * NYET occurs at the same time as a Transfer Complete interrupt, it is
 * handled in the xfercomp interrupt handler, not here. This handler may be
 * called in either DMA mode or Slave mode.
 */
static void dwc2_hc_nyet_intr(struct dwc2_hsotg *hsotg,
                              struct dwc2_host_chan *chan, int chnum,
                              struct dwc2_qtd *qtd)
{
        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev, "--Host Channel %d Interrupt: NYET Received--\n",
                         chnum);

        /*
         * NYET on CSPLIT
         * re-do the CSPLIT immediately on non-periodic
         */
        if (chan->do_split && chan->complete_split) {
                if (chan->ep_is_in && chan->ep_type == USB_ENDPOINT_XFER_ISOC &&
                    hsotg->params.host_dma) {
                        qtd->complete_split = 0;
                        qtd->isoc_split_offset = 0;
                        qtd->isoc_frame_index++;
                        if (qtd->urb &&
                            qtd->isoc_frame_index == qtd->urb->packet_count) {
                                dwc2_host_complete(hsotg, qtd, 0);
                                dwc2_release_channel(hsotg, chan, qtd,
                                                     DWC2_HC_XFER_URB_COMPLETE);
                        } else {
                                dwc2_release_channel(hsotg, chan, qtd,
                                                DWC2_HC_XFER_NO_HALT_STATUS);
                        }
                        goto handle_nyet_done;
                }

                if (chan->ep_type == USB_ENDPOINT_XFER_INT ||
                    chan->ep_type == USB_ENDPOINT_XFER_ISOC) {
                        struct dwc2_qh *qh = chan->qh;
                        bool past_end;

                        if (!hsotg->params.uframe_sched) {
                                int frnum = dwc2_hcd_get_frame_number(hsotg);

                                /* Don't have num_hs_transfers; simple logic */
                                past_end = dwc2_full_frame_num(frnum) !=
                                     dwc2_full_frame_num(qh->next_active_frame);
                        } else {
                                int end_frnum;

                                /*
                                 * Figure out the end frame based on
                                 * schedule.
                                 *
                                 * We don't want to go on trying again
                                 * and again forever. Let's stop when
                                 * we've done all the transfers that
                                 * were scheduled.
                                 *
                                 * We're going to be comparing
                                 * start_active_frame and
                                 * next_active_frame, both of which
                                 * are 1 before the time the packet
                                 * goes on the wire, so that cancels
                                 * out. Basically if had 1 transfer
                                 * and we saw 1 NYET then we're done.
                                 * We're getting a NYET here so if
                                 * next >= (start + num_transfers)
                                 * we're done. The complexity is that
                                 * for all but ISOC_OUT we skip one
                                 * slot.
                                 */
                                end_frnum = dwc2_frame_num_inc(
                                        qh->start_active_frame,
                                        qh->num_hs_transfers);

                                if (qh->ep_type != USB_ENDPOINT_XFER_ISOC ||
                                    qh->ep_is_in)
                                        end_frnum =
                                               dwc2_frame_num_inc(end_frnum, 1);

                                past_end = dwc2_frame_num_le(
                                        end_frnum, qh->next_active_frame);
                        }

                        if (past_end) {
                                /* Treat this as a transaction error. */
#if 0
                                /*
                                 * Todo: Fix system performance so this can
                                 * be treated as an error. Right now complete
                                 * splits cannot be scheduled precisely enough
                                 * due to other system activity, so this error
                                 * occurs regularly in Slave mode.
                                 */
                                qtd->error_count++;
#endif
                                qtd->complete_split = 0;
                                dwc2_halt_channel(hsotg, chan, qtd,
                                                  DWC2_HC_XFER_XACT_ERR);
                                /* Todo: add support for isoc release */
                                goto handle_nyet_done;
                        }
                }

                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NYET);
                goto handle_nyet_done;
        }

        chan->qh->ping_state = 1;
        qtd->error_count = 0;

        dwc2_update_urb_state_abn(hsotg, chan, chnum, qtd->urb, qtd,
                                  DWC2_HC_XFER_NYET);
        dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);

        /*
         * Halt the channel and re-start the transfer so the PING protocol
         * will start
         */
        dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_NYET);

handle_nyet_done:
        disable_hc_int(hsotg, chnum, HCINTMSK_NYET);
}

/*
 * Handles a host channel babble interrupt. This handler may be called in
 * either DMA mode or Slave mode.
 */
static void dwc2_hc_babble_intr(struct dwc2_hsotg *hsotg,
                                struct dwc2_host_chan *chan, int chnum,
                                struct dwc2_qtd *qtd)
{
        dev_dbg(hsotg->dev, "--Host Channel %d Interrupt: Babble Error--\n",
                chnum);

        dwc2_hc_handle_tt_clear(hsotg, chan, qtd);

        if (hsotg->params.dma_desc_enable) {
                dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum,
                                            DWC2_HC_XFER_BABBLE_ERR);
                goto disable_int;
        }

        if (chan->ep_type != USB_ENDPOINT_XFER_ISOC) {
                dwc2_host_complete(hsotg, qtd, -EOVERFLOW);
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_BABBLE_ERR);
        } else {
                enum dwc2_halt_status halt_status;

                halt_status = dwc2_update_isoc_urb_state(hsotg, chan, chnum,
                                                qtd, DWC2_HC_XFER_BABBLE_ERR);
                dwc2_halt_channel(hsotg, chan, qtd, halt_status);
        }

disable_int:
        disable_hc_int(hsotg, chnum, HCINTMSK_BBLERR);
}

/*
 * Handles a host channel AHB error interrupt. This handler is only called in
 * DMA mode.
 */
static void dwc2_hc_ahberr_intr(struct dwc2_hsotg *hsotg,
                                struct dwc2_host_chan *chan, int chnum,
                                struct dwc2_qtd *qtd)
{
        struct dwc2_hcd_urb *urb = qtd->urb;
        char *pipetype, *speed;
        u32 hcchar;
        u32 hcsplt;
        u32 hctsiz;
        u32 hc_dma;

        dev_dbg(hsotg->dev, "--Host Channel %d Interrupt: AHB Error--\n",
                chnum);

        if (!urb)
                goto handle_ahberr_halt;

        dwc2_hc_handle_tt_clear(hsotg, chan, qtd);

        hcchar = dwc2_readl(hsotg, HCCHAR(chnum));
        hcsplt = dwc2_readl(hsotg, HCSPLT(chnum));
        hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));
        hc_dma = dwc2_readl(hsotg, HCDMA(chnum));

        dev_err(hsotg->dev, "AHB ERROR, Channel %d\n", chnum);
        dev_err(hsotg->dev, "  hcchar 0x%08x, hcsplt 0x%08x\n", hcchar, hcsplt);
        dev_err(hsotg->dev, "  hctsiz 0x%08x, hc_dma 0x%08x\n", hctsiz, hc_dma);
        dev_err(hsotg->dev, "  Device address: %d\n",
                dwc2_hcd_get_dev_addr(&urb->pipe_info));
        dev_err(hsotg->dev, "  Endpoint: %d, %s\n",
                dwc2_hcd_get_ep_num(&urb->pipe_info),
                dwc2_hcd_is_pipe_in(&urb->pipe_info) ? "IN" : "OUT");

        switch (dwc2_hcd_get_pipe_type(&urb->pipe_info)) {
        case USB_ENDPOINT_XFER_CONTROL:
                pipetype = "CONTROL";
                break;
        case USB_ENDPOINT_XFER_BULK:
                pipetype = "BULK";
                break;
        case USB_ENDPOINT_XFER_INT:
                pipetype = "INTERRUPT";
                break;
        case USB_ENDPOINT_XFER_ISOC:
                pipetype = "ISOCHRONOUS";
                break;
        default:
                pipetype = "UNKNOWN";
                break;
        }

        dev_err(hsotg->dev, "  Endpoint type: %s\n", pipetype);

        switch (chan->speed) {
        case USB_SPEED_HIGH:
                speed = "HIGH";
                break;
        case USB_SPEED_FULL:
                speed = "FULL";
                break;
        case USB_SPEED_LOW:
                speed = "LOW";
                break;
        default:
                speed = "UNKNOWN";
                break;
        }

        dev_err(hsotg->dev, "  Speed: %s\n", speed);

        dev_err(hsotg->dev, "  Max packet size: %d (mult %d)\n",
                dwc2_hcd_get_maxp(&urb->pipe_info),
                dwc2_hcd_get_maxp_mult(&urb->pipe_info));
        dev_err(hsotg->dev, "  Data buffer length: %d\n", urb->length);
        dev_err(hsotg->dev, "  Transfer buffer: %p, Transfer DMA: %08lx\n",
                urb->buf, (unsigned long)urb->dma);
        dev_err(hsotg->dev, "  Setup buffer: %p, Setup DMA: %08lx\n",
                urb->setup_packet, (unsigned long)urb->setup_dma);
        dev_err(hsotg->dev, "  Interval: %d\n", urb->interval);

        /* Core halts the channel for Descriptor DMA mode */
        if (hsotg->params.dma_desc_enable) {
                dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum,
                                            DWC2_HC_XFER_AHB_ERR);
                goto handle_ahberr_done;
        }

        dwc2_host_complete(hsotg, qtd, -EIO);

handle_ahberr_halt:
        /*
         * Force a channel halt. Don't call dwc2_halt_channel because that won't
         * write to the HCCHARn register in DMA mode to force the halt.
         */
        dwc2_hc_halt(hsotg, chan, DWC2_HC_XFER_AHB_ERR);

handle_ahberr_done:
        disable_hc_int(hsotg, chnum, HCINTMSK_AHBERR);
}

/*
 * Handles a host channel transaction error interrupt. This handler may be
 * called in either DMA mode or Slave mode.
 */
static void dwc2_hc_xacterr_intr(struct dwc2_hsotg *hsotg,
                                 struct dwc2_host_chan *chan, int chnum,
                                 struct dwc2_qtd *qtd)
{
        dev_dbg(hsotg->dev,
                "--Host Channel %d Interrupt: Transaction Error--\n", chnum);

        dwc2_hc_handle_tt_clear(hsotg, chan, qtd);

        if (hsotg->params.dma_desc_enable) {
                dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum,
                                            DWC2_HC_XFER_XACT_ERR);
                goto handle_xacterr_done;
        }

        switch (dwc2_hcd_get_pipe_type(&qtd->urb->pipe_info)) {
        case USB_ENDPOINT_XFER_CONTROL:
        case USB_ENDPOINT_XFER_BULK:
                qtd->error_count++;
                if (!chan->qh->ping_state) {
                        dwc2_update_urb_state_abn(hsotg, chan, chnum, qtd->urb,
                                                  qtd, DWC2_HC_XFER_XACT_ERR);
                        dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);
                        if (!chan->ep_is_in && chan->speed == USB_SPEED_HIGH)
                                chan->qh->ping_state = 1;
                }

                /*
                 * Halt the channel so the transfer can be re-started from
                 * the appropriate point or the PING protocol will start
                 */
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_XACT_ERR);
                break;
        case USB_ENDPOINT_XFER_INT:
                qtd->error_count++;
                if (chan->do_split && chan->complete_split)
                        qtd->complete_split = 0;
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_XACT_ERR);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                {
                        enum dwc2_halt_status halt_status;

                        halt_status = dwc2_update_isoc_urb_state(hsotg, chan,
                                         chnum, qtd, DWC2_HC_XFER_XACT_ERR);
                        dwc2_halt_channel(hsotg, chan, qtd, halt_status);
                }
                break;
        }

handle_xacterr_done:
        disable_hc_int(hsotg, chnum, HCINTMSK_XACTERR);
}

/*
 * Handles a host channel frame overrun interrupt. This handler may be called
 * in either DMA mode or Slave mode.
 */
static void dwc2_hc_frmovrun_intr(struct dwc2_hsotg *hsotg,
                                  struct dwc2_host_chan *chan, int chnum,
                                  struct dwc2_qtd *qtd)
{
        enum dwc2_halt_status halt_status;

        if (dbg_hc(chan))
                dev_dbg(hsotg->dev, "--Host Channel %d Interrupt: Frame Overrun--\n",
                        chnum);

        dwc2_hc_handle_tt_clear(hsotg, chan, qtd);

        switch (dwc2_hcd_get_pipe_type(&qtd->urb->pipe_info)) {
        case USB_ENDPOINT_XFER_CONTROL:
        case USB_ENDPOINT_XFER_BULK:
                break;
        case USB_ENDPOINT_XFER_INT:
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_FRAME_OVERRUN);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                halt_status = dwc2_update_isoc_urb_state(hsotg, chan, chnum,
                                        qtd, DWC2_HC_XFER_FRAME_OVERRUN);
                dwc2_halt_channel(hsotg, chan, qtd, halt_status);
                break;
        }

        disable_hc_int(hsotg, chnum, HCINTMSK_FRMOVRUN);
}

/*
 * Handles a host channel data toggle error interrupt. This handler may be
 * called in either DMA mode or Slave mode.
 */
static void dwc2_hc_datatglerr_intr(struct dwc2_hsotg *hsotg,
                                    struct dwc2_host_chan *chan, int chnum,
                                    struct dwc2_qtd *qtd)
{
        dev_dbg(hsotg->dev,
                "--Host Channel %d Interrupt: Data Toggle Error--\n", chnum);

        if (chan->ep_is_in)
                qtd->error_count = 0;
        else
                dev_err(hsotg->dev,
                        "Data Toggle Error on OUT transfer, channel %d\n",
                        chnum);

        dwc2_hc_handle_tt_clear(hsotg, chan, qtd);
        disable_hc_int(hsotg, chnum, HCINTMSK_DATATGLERR);
}

/*
 * For debug only. It checks that a valid halt status is set and that
 * HCCHARn.chdis is clear. If there's a problem, corrective action is
 * taken and a warning is issued.
 *
 * Return: true if halt status is ok, false otherwise
 */
static bool dwc2_halt_status_ok(struct dwc2_hsotg *hsotg,
                                struct dwc2_host_chan *chan, int chnum,
                                struct dwc2_qtd *qtd)
{
#ifdef DEBUG
        u32 hcchar;
        u32 hctsiz;
        u32 hcintmsk;
        u32 hcsplt;

        if (chan->halt_status == DWC2_HC_XFER_NO_HALT_STATUS) {
                /*
                 * This code is here only as a check. This condition should
                 * never happen. Ignore the halt if it does occur.
                 */
                hcchar = dwc2_readl(hsotg, HCCHAR(chnum));
                hctsiz = dwc2_readl(hsotg, HCTSIZ(chnum));
                hcintmsk = dwc2_readl(hsotg, HCINTMSK(chnum));
                hcsplt = dwc2_readl(hsotg, HCSPLT(chnum));
                dev_dbg(hsotg->dev,
                        "%s: chan->halt_status DWC2_HC_XFER_NO_HALT_STATUS,\n",
                         __func__);
                dev_dbg(hsotg->dev,
                        "channel %d, hcchar 0x%08x, hctsiz 0x%08x,\n",
                        chnum, hcchar, hctsiz);
                dev_dbg(hsotg->dev,
                        "hcint 0x%08x, hcintmsk 0x%08x, hcsplt 0x%08x,\n",
                        chan->hcint, hcintmsk, hcsplt);
                if (qtd)
                        dev_dbg(hsotg->dev, "qtd->complete_split %d\n",
                                qtd->complete_split);
                dev_warn(hsotg->dev,
                         "%s: no halt status, channel %d, ignoring interrupt\n",
                         __func__, chnum);
                return false;
        }

        /*
         * This code is here only as a check. hcchar.chdis should never be set
         * when the halt interrupt occurs. Halt the channel again if it does
         * occur.
         */
        hcchar = dwc2_readl(hsotg, HCCHAR(chnum));
        if (hcchar & HCCHAR_CHDIS) {
                dev_warn(hsotg->dev,
                         "%s: hcchar.chdis set unexpectedly, hcchar 0x%08x, trying to halt again\n",
                         __func__, hcchar);
                chan->halt_pending = 0;
                dwc2_halt_channel(hsotg, chan, qtd, chan->halt_status);
                return false;
        }
#endif

        return true;
}

/*
 * Handles a host Channel Halted interrupt in DMA mode. This handler
 * determines the reason the channel halted and proceeds accordingly.
 */
static void dwc2_hc_chhltd_intr_dma(struct dwc2_hsotg *hsotg,
                                    struct dwc2_host_chan *chan, int chnum,
                                    struct dwc2_qtd *qtd)
{
        u32 hcintmsk;
        int out_nak_enh = 0;

        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev,
                         "--Host Channel %d Interrupt: DMA Channel Halted--\n",
                         chnum);

        /*
         * For core with OUT NAK enhancement, the flow for high-speed
         * CONTROL/BULK OUT is handled a little differently
         */
        if (hsotg->hw_params.snpsid >= DWC2_CORE_REV_2_71a) {
                if (chan->speed == USB_SPEED_HIGH && !chan->ep_is_in &&
                    (chan->ep_type == USB_ENDPOINT_XFER_CONTROL ||
                     chan->ep_type == USB_ENDPOINT_XFER_BULK)) {
                        out_nak_enh = 1;
                }
        }

        if (chan->halt_status == DWC2_HC_XFER_URB_DEQUEUE ||
            (chan->halt_status == DWC2_HC_XFER_AHB_ERR &&
             !hsotg->params.dma_desc_enable)) {
                if (hsotg->params.dma_desc_enable)
                        dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum,
                                                    chan->halt_status);
                else
                        /*
                         * Just release the channel. A dequeue can happen on a
                         * transfer timeout. In the case of an AHB Error, the
                         * channel was forced to halt because there's no way to
                         * gracefully recover.
                         */
                        dwc2_release_channel(hsotg, chan, qtd,
                                             chan->halt_status);
                return;
        }

        hcintmsk = dwc2_readl(hsotg, HCINTMSK(chnum));

        if (chan->hcint & HCINTMSK_XFERCOMPL) {
                /*
                 * Todo: This is here because of a possible hardware bug. Spec
                 * says that on SPLIT-ISOC OUT transfers in DMA mode that a HALT
                 * interrupt w/ACK bit set should occur, but I only see the
                 * XFERCOMP bit, even with it masked out. This is a workaround
                 * for that behavior. Should fix this when hardware is fixed.
                 */
                if (chan->ep_type == USB_ENDPOINT_XFER_ISOC && !chan->ep_is_in)
                        dwc2_hc_ack_intr(hsotg, chan, chnum, qtd);
                dwc2_hc_xfercomp_intr(hsotg, chan, chnum, qtd);
        } else if (chan->hcint & HCINTMSK_STALL) {
                dwc2_hc_stall_intr(hsotg, chan, chnum, qtd);
        } else if ((chan->hcint & HCINTMSK_XACTERR) &&
                   !hsotg->params.dma_desc_enable) {
                if (out_nak_enh) {
                        if (chan->hcint &
                            (HCINTMSK_NYET | HCINTMSK_NAK | HCINTMSK_ACK)) {
                                dev_vdbg(hsotg->dev,
                                         "XactErr with NYET/NAK/ACK\n");
                                qtd->error_count = 0;
                        } else {
                                dev_vdbg(hsotg->dev,
                                         "XactErr without NYET/NAK/ACK\n");
                        }
                }

                /*
                 * Must handle xacterr before nak or ack. Could get a xacterr
                 * at the same time as either of these on a BULK/CONTROL OUT
                 * that started with a PING. The xacterr takes precedence.
                 */
                dwc2_hc_xacterr_intr(hsotg, chan, chnum, qtd);
        } else if ((chan->hcint & HCINTMSK_XCS_XACT) &&
                   hsotg->params.dma_desc_enable) {
                dwc2_hc_xacterr_intr(hsotg, chan, chnum, qtd);
        } else if ((chan->hcint & HCINTMSK_AHBERR) &&
                   hsotg->params.dma_desc_enable) {
                dwc2_hc_ahberr_intr(hsotg, chan, chnum, qtd);
        } else if (chan->hcint & HCINTMSK_BBLERR) {
                dwc2_hc_babble_intr(hsotg, chan, chnum, qtd);
        } else if (chan->hcint & HCINTMSK_FRMOVRUN) {
                dwc2_hc_frmovrun_intr(hsotg, chan, chnum, qtd);
        } else if (!out_nak_enh) {
                if (chan->hcint & HCINTMSK_NYET) {
                        /*
                         * Must handle nyet before nak or ack. Could get a nyet
                         * at the same time as either of those on a BULK/CONTROL
                         * OUT that started with a PING. The nyet takes
                         * precedence.
                         */
                        dwc2_hc_nyet_intr(hsotg, chan, chnum, qtd);
                } else if ((chan->hcint & HCINTMSK_NAK) &&
                           !(hcintmsk & HCINTMSK_NAK)) {
                        /*
                         * If nak is not masked, it's because a non-split IN
                         * transfer is in an error state. In that case, the nak
                         * is handled by the nak interrupt handler, not here.
                         * Handle nak here for BULK/CONTROL OUT transfers, which
                         * halt on a NAK to allow rewinding the buffer pointer.
                         */
                        dwc2_hc_nak_intr(hsotg, chan, chnum, qtd);
                } else if ((chan->hcint & HCINTMSK_ACK) &&
                           !(hcintmsk & HCINTMSK_ACK)) {
                        /*
                         * If ack is not masked, it's because a non-split IN
                         * transfer is in an error state. In that case, the ack
                         * is handled by the ack interrupt handler, not here.
                         * Handle ack here for split transfers. Start splits
                         * halt on ACK.
                         */
                        dwc2_hc_ack_intr(hsotg, chan, chnum, qtd);
                } else {
                        if (chan->ep_type == USB_ENDPOINT_XFER_INT ||
                            chan->ep_type == USB_ENDPOINT_XFER_ISOC) {
                                /*
                                 * A periodic transfer halted with no other
                                 * channel interrupts set. Assume it was halted
                                 * by the core because it could not be completed
                                 * in its scheduled (micro)frame.
                                 */
                                dev_dbg(hsotg->dev,
                                        "%s: Halt channel %d (assume incomplete periodic transfer)\n",
                                        __func__, chnum);
                                dwc2_halt_channel(hsotg, chan, qtd,
                                        DWC2_HC_XFER_PERIODIC_INCOMPLETE);
                        } else {
                                dev_err(hsotg->dev,
                                        "%s: Channel %d - ChHltd set, but reason is unknown\n",
                                        __func__, chnum);
                                dev_err(hsotg->dev,
                                        "hcint 0x%08x, intsts 0x%08x\n",
                                        chan->hcint,
                                        dwc2_readl(hsotg, GINTSTS));
                                goto error;
                        }
                }
        } else {
                dev_info(hsotg->dev,
                         "NYET/NAK/ACK/other in non-error case, 0x%08x\n",
                         chan->hcint);
error:
                /* Failthrough: use 3-strikes rule */
                qtd->error_count++;
                dwc2_update_urb_state_abn(hsotg, chan, chnum, qtd->urb,
                                          qtd, DWC2_HC_XFER_XACT_ERR);
                /*
                 * We can get here after a completed transaction
                 * (urb->actual_length >= urb->length) which was not reported
                 * as completed. If that is the case, and we do not abort
                 * the transfer, a transfer of size 0 will be enqueued
                 * subsequently. If urb->actual_length is not DMA-aligned,
                 * the buffer will then point to an unaligned address, and
                 * the resulting behavior is undefined. Bail out in that
                 * situation.
                 */
                if (qtd->urb->actual_length >= qtd->urb->length)
                        qtd->error_count = 3;
                dwc2_hcd_save_data_toggle(hsotg, chan, chnum, qtd);
                dwc2_halt_channel(hsotg, chan, qtd, DWC2_HC_XFER_XACT_ERR);
        }
}

/*
 * Handles a host channel Channel Halted interrupt
 *
 * In slave mode, this handler is called only when the driver specifically

 * requests a halt. This occurs during handling other host channel interrupts
 * (e.g. nak, xacterr, stall, nyet, etc.).
 *
 * In DMA mode, this is the interrupt that occurs when the core has finished
 * processing a transfer on a channel. Other host channel interrupts (except
 * ahberr) are disabled in DMA mode.
 */
static void dwc2_hc_chhltd_intr(struct dwc2_hsotg *hsotg,
                                struct dwc2_host_chan *chan, int chnum,
                                struct dwc2_qtd *qtd)
{
        if (dbg_hc(chan))
                dev_vdbg(hsotg->dev, "--Host Channel %d Interrupt: Channel Halted--\n",
                         chnum);

        if (hsotg->params.host_dma) {
                dwc2_hc_chhltd_intr_dma(hsotg, chan, chnum, qtd);
        } else {
                if (!dwc2_halt_status_ok(hsotg, chan, chnum, qtd))
                        return;
                dwc2_release_channel(hsotg, chan, qtd, chan->halt_status);
        }
}

/*
 * Check if the given qtd is still the top of the list (and thus valid).
 *
 * If dwc2_hcd_qtd_unlink_and_free() has been called since we grabbed
 * the qtd from the top of the list, this will return false (otherwise true).
 */
static bool dwc2_check_qtd_still_ok(struct dwc2_qtd *qtd, struct dwc2_qh *qh)
{
        struct dwc2_qtd *cur_head;

        if (!qh)
                return false;

        cur_head = list_first_entry(&qh->qtd_list, struct dwc2_qtd,
                                    qtd_list_entry);
        return (cur_head == qtd);
}

/* Handles interrupt for a specific Host Channel */
static void dwc2_hc_n_intr(struct dwc2_hsotg *hsotg, int chnum)
{
        struct dwc2_qtd *qtd;
        struct dwc2_host_chan *chan;
        u32 hcint, hcintmsk;

        chan = hsotg->hc_ptr_array[chnum];

        hcint = dwc2_readl(hsotg, HCINT(chnum));
        hcintmsk = dwc2_readl(hsotg, HCINTMSK(chnum));
        if (!chan) {
                dev_err(hsotg->dev, "## hc_ptr_array for channel is NULL ##\n");
                dwc2_writel(hsotg, hcint, HCINT(chnum));
                return;
        }

        if (dbg_hc(chan)) {
                dev_vdbg(hsotg->dev, "--Host Channel Interrupt--, Channel %d\n",
                         chnum);
                dev_vdbg(hsotg->dev,
                         "  hcint 0x%08x, hcintmsk 0x%08x, hcint&hcintmsk 0x%08x\n",
                         hcint, hcintmsk, hcint & hcintmsk);
        }

        dwc2_writel(hsotg, hcint, HCINT(chnum));

        /*
         * If we got an interrupt after someone called
         * dwc2_hcd_endpoint_disable() we don't want to crash below
         */
        if (!chan->qh) {
                dev_warn(hsotg->dev, "Interrupt on disabled channel\n");
                return;
        }

        chan->hcint = hcint;
        hcint &= hcintmsk;

        /*
         * If the channel was halted due to a dequeue, the qtd list might
         * be empty or at least the first entry will not be the active qtd.
         * In this case, take a shortcut and just release the channel.
         */
        if (chan->halt_status == DWC2_HC_XFER_URB_DEQUEUE) {
                /*
                 * If the channel was halted, this should be the only
                 * interrupt unmasked
                 */
                WARN_ON(hcint != HCINTMSK_CHHLTD);
                if (hsotg->params.dma_desc_enable)
                        dwc2_hcd_complete_xfer_ddma(hsotg, chan, chnum,
                                                    chan->halt_status);
                else
                        dwc2_release_channel(hsotg, chan, NULL,
                                             chan->halt_status);
                return;
        }

        if (list_empty(&chan->qh->qtd_list)) {
                /*
                 * TODO: Will this ever happen with the
                 * DWC2_HC_XFER_URB_DEQUEUE handling above?
                 */
                dev_dbg(hsotg->dev, "## no QTD queued for channel %d ##\n",
                        chnum);
                dev_dbg(hsotg->dev,
                        "  hcint 0x%08x, hcintmsk 0x%08x, hcint&hcintmsk 0x%08x\n",
                        chan->hcint, hcintmsk, hcint);
                chan->halt_status = DWC2_HC_XFER_NO_HALT_STATUS;
                disable_hc_int(hsotg, chnum, HCINTMSK_CHHLTD);
                chan->hcint = 0;
                return;
        }

        qtd = list_first_entry(&chan->qh->qtd_list, struct dwc2_qtd,
                               qtd_list_entry);

        if (!hsotg->params.host_dma) {
                if ((hcint & HCINTMSK_CHHLTD) && hcint != HCINTMSK_CHHLTD)
                        hcint &= ~HCINTMSK_CHHLTD;
        }

        if (hcint & HCINTMSK_XFERCOMPL) {
                dwc2_hc_xfercomp_intr(hsotg, chan, chnum, qtd);
                /*
                 * If NYET occurred at same time as Xfer Complete, the NYET is
                 * handled by the Xfer Complete interrupt handler. Don't want
                 * to call the NYET interrupt handler in this case.
                 */
                hcint &= ~HCINTMSK_NYET;
        }

        if (hcint & HCINTMSK_CHHLTD) {
                dwc2_hc_chhltd_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_AHBERR) {
                dwc2_hc_ahberr_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_STALL) {
                dwc2_hc_stall_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_NAK) {
                dwc2_hc_nak_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_ACK) {
                dwc2_hc_ack_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_NYET) {
                dwc2_hc_nyet_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_XACTERR) {
                dwc2_hc_xacterr_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_BBLERR) {
                dwc2_hc_babble_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_FRMOVRUN) {
                dwc2_hc_frmovrun_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }
        if (hcint & HCINTMSK_DATATGLERR) {
                dwc2_hc_datatglerr_intr(hsotg, chan, chnum, qtd);
                if (!dwc2_check_qtd_still_ok(qtd, chan->qh))
                        goto exit;
        }

exit:
        chan->hcint = 0;
}

/*
 * This interrupt indicates that one or more host channels has a pending
 * interrupt. There are multiple conditions that can cause each host channel
 * interrupt. This function determines which conditions have occurred for each
 * host channel interrupt and handles them appropriately.
 */
static void dwc2_hc_intr(struct dwc2_hsotg *hsotg)
{
        u32 haint;
        int i;
        struct dwc2_host_chan *chan, *chan_tmp;

        haint = dwc2_readl(hsotg, HAINT);
        if (dbg_perio()) {
                dev_vdbg(hsotg->dev, "%s()\n", __func__);

                dev_vdbg(hsotg->dev, "HAINT=%08x\n", haint);
        }

        /*
         * According to USB 2.0 spec section 11.18.8, a host must
         * issue complete-split transactions in a microframe for a
         * set of full-/low-speed endpoints in the same relative
         * order as the start-splits were issued in a microframe for.
         */
        list_for_each_entry_safe(chan, chan_tmp, &hsotg->split_order,
                                 split_order_list_entry) {
                int hc_num = chan->hc_num;

                if (haint & (1 << hc_num)) {
                        dwc2_hc_n_intr(hsotg, hc_num);
                        haint &= ~(1 << hc_num);
                }
        }

        for (i = 0; i < hsotg->params.host_channels; i++) {
                if (haint & (1 << i))
                        dwc2_hc_n_intr(hsotg, i);
        }
}

/* This function handles interrupts for the HCD */
irqreturn_t dwc2_handle_hcd_intr(struct dwc2_hsotg *hsotg)
{
        u32 gintsts, dbg_gintsts;
        irqreturn_t retval = IRQ_NONE;

        if (!dwc2_is_controller_alive(hsotg)) {
                dev_warn(hsotg->dev, "Controller is dead\n");
                return retval;
        }

        spin_lock(&hsotg->lock);

        /* Check if HOST Mode */
        if (dwc2_is_host_mode(hsotg)) {
                gintsts = dwc2_read_core_intr(hsotg);
                if (!gintsts) {
                        spin_unlock(&hsotg->lock);
                        return retval;
                }

                retval = IRQ_HANDLED;

                dbg_gintsts = gintsts;
#ifndef DEBUG_SOF
                dbg_gintsts &= ~GINTSTS_SOF;
#endif
                if (!dbg_perio())
                        dbg_gintsts &= ~(GINTSTS_HCHINT | GINTSTS_RXFLVL |
                                         GINTSTS_PTXFEMP);

                /* Only print if there are any non-suppressed interrupts left */
                if (dbg_gintsts)
                        dev_vdbg(hsotg->dev,
                                 "DWC OTG HCD Interrupt Detected gintsts&gintmsk=0x%08x\n",
                                 gintsts);

                if (gintsts & GINTSTS_SOF)
                        dwc2_sof_intr(hsotg);
                if (gintsts & GINTSTS_RXFLVL)
                        dwc2_rx_fifo_level_intr(hsotg);
                if (gintsts & GINTSTS_NPTXFEMP)
                        dwc2_np_tx_fifo_empty_intr(hsotg);
                if (gintsts & GINTSTS_PRTINT)
                        dwc2_port_intr(hsotg);
                if (gintsts & GINTSTS_HCHINT)
                        dwc2_hc_intr(hsotg);
                if (gintsts & GINTSTS_PTXFEMP)
                        dwc2_perio_tx_fifo_empty_intr(hsotg);

                if (dbg_gintsts) {
                        dev_vdbg(hsotg->dev,
                                 "DWC OTG HCD Finished Servicing Interrupts\n");
                        dev_vdbg(hsotg->dev,
                                 "DWC OTG HCD gintsts=0x%08x gintmsk=0x%08x\n",
                                 dwc2_readl(hsotg, GINTSTS),
                                 dwc2_readl(hsotg, GINTMSK));
                }
        }

        spin_unlock(&hsotg->lock);

        return retval;
}