Merge omap-drivers

[linux-2.6-omap-h63xx.git] / drivers / usb / musb / musb_host.c

/******************************************************************
 * Copyright 2005 Mentor Graphics Corporation
 * Copyright (C) 2005-2006 by Texas Instruments
 * Copyright (C) 2006 by Nokia Corporation
 *
 * This file is part of the Inventra Controller Driver for Linux.
 *
 * The Inventra Controller Driver for Linux is free software; you
 * can redistribute it and/or modify it under the terms of the GNU
 * General Public License version 2 as published by the Free Software
 * Foundation.
 *
 * The Inventra Controller Driver for Linux is distributed in
 * the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
 * License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with The Inventra Controller Driver for Linux ; if not,
 * write to the Free Software Foundation, Inc., 59 Temple Place,
 * Suite 330, Boston, MA  02111-1307  USA
 *
 * ANY DOWNLOAD, USE, REPRODUCTION, MODIFICATION OR DISTRIBUTION
 * OF THIS DRIVER INDICATES YOUR COMPLETE AND UNCONDITIONAL ACCEPTANCE
 * OF THOSE TERMS.THIS DRIVER IS PROVIDED "AS IS" AND MENTOR GRAPHICS
 * MAKES NO WARRANTIES, EXPRESS OR IMPLIED, RELATED TO THIS DRIVER.
 * MENTOR GRAPHICS SPECIFICALLY DISCLAIMS ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY; FITNESS FOR A PARTICULAR PURPOSE AND
 * NON-INFRINGEMENT.  MENTOR GRAPHICS DOES NOT PROVIDE SUPPORT
 * SERVICES OR UPDATES FOR THIS DRIVER, EVEN IF YOU ARE A MENTOR
 * GRAPHICS SUPPORT CUSTOMER.
 ******************************************************************/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/list.h>

#include "musbdefs.h"
#include "musb_host.h"


/* MUSB HOST status 22-mar-2006
 *
 * - There's still lots of partial code duplication for fault paths, so
 *   they aren't handled as consistently as they need to be.
 *
 * - PIO mostly behaved when last tested.
 *     + including ep0, with all usbtest cases 9, 10
 *     + usbtest 14 (ep0out) doesn't seem to run at all
 *     + double buffered OUT/TX endpoints saw stalls(!) with certain usbtest
 *       configurations, but otherwise double buffering passes basic tests.
 *     + for 2.6.N, for N > ~10, needs API changes for hcd framework.
 *
 * - DMA (CPPI) ... partially behaves, not currently recommended
 *     + about 1/15 the speed of typical EHCI implementations (PCI)
 *     + RX, all too often reqpkt seems to misbehave after tx
 *     + TX, no known issues (other than evident silicon issue)
 *
 * - DMA (Mentor/OMAP) ...has at least toggle update problems
 *
 * - Still no traffic scheduling code to make NAKing for bulk or control
 *   transfers unable to starve other requests; or to make efficient use
 *   of hardware with periodic transfers.  (Note that network drivers
 *   commonly post bulk reads that stay pending for a long time; these
 *   would make very visible trouble.)
 *
 * - Not tested with HNP, but some SRP paths seem to behave.
 *
 * NOTE 24-August:
 *
 * - Bulk traffic finally uses both sides of hardware ep1, freeing up an
 *   extra endpoint for periodic use enabling hub + keybd + mouse.  That
 *   mostly works, except that with "usbnet" it's easy to trigger cases
 *   with "ping" where RX loses.  (a) ping to davinci, even "ping -f",
 *   fine; but (b) ping _from_ davinci, even "ping -c 1", ICMP RX loses
 *   although ARP RX wins.  (That test was done with a full speed link.)
 */


/*
 * NOTE on endpoint usage:
 *
 * CONTROL transfers all go through ep0.  BULK ones go through dedicated IN
 * and OUT endpoints ... hardware is dedicated for those "async" queue(s).
 *
 * (Yes, bulk _could_ use more of the endpoints than that, and would even
 * benefit from it ... one remote device may easily be NAKing while others
 * need to perform transfers in that same direction.  The same thing could
 * be done in software though, assuming dma cooperates.)
 *
 * INTERUPPT and ISOCHRONOUS transfers are scheduled to the other endpoints.
 * So far that scheduling is both dumb and optimistic:  the endpoint will be
 * "claimed" until its software queue is no longer refilled.  No multiplexing
 * of transfers between endpoints, or anything clever.
 */


/*************************** Forwards ***************************/

static void musb_ep_program(struct musb *pThis, u8 bEnd,
                        struct urb *pUrb, unsigned int nOut,
                        u8 * pBuffer, u32 dwLength);

/*
 * Start transmit. Caller is responsible for locking shared resources.
 * pThis must be locked.
 */
static inline void musb_h_tx_start(struct musb_hw_ep *ep)
{
        u16     txcsr;

        /* NOTE: no locks here; caller should lock and select EP */
        if (ep->bLocalEnd) {
                txcsr = musb_readw(ep->regs, MGC_O_HDRC_TXCSR);
                txcsr |= MGC_M_TXCSR_TXPKTRDY | MGC_M_TXCSR_H_WZC_BITS;
                musb_writew(ep->regs, MGC_O_HDRC_TXCSR, txcsr);
        } else {
                txcsr = MGC_M_CSR0_H_SETUPPKT | MGC_M_CSR0_TXPKTRDY;
                musb_writew(ep->regs, MGC_O_HDRC_CSR0, txcsr);
        }

}

static inline void cppi_host_txdma_start(struct musb_hw_ep *ep)
{
        u16     txcsr;

        /* NOTE: no locks here; caller should lock and select EP */
        txcsr = musb_readw(ep->regs, MGC_O_HDRC_TXCSR);
        txcsr |= MGC_M_TXCSR_DMAENAB | MGC_M_TXCSR_H_WZC_BITS;
        musb_writew(ep->regs, MGC_O_HDRC_TXCSR, txcsr);
}

/*
 * Start the URB at the front of an endpoint's queue
 * end must be claimed from the caller.
 *
 * Context: controller locked, irqs blocked
 */
static void
musb_start_urb(struct musb *musb, int is_in, struct musb_qh *qh)
{
        u16                     wFrame;
        u32                     dwLength;
        void                    *pBuffer;
        void __iomem            *pBase =  musb->pRegs;
        struct urb              *urb = next_urb(qh);
        struct musb_hw_ep       *pEnd = qh->hw_ep;
        unsigned                nPipe = urb->pipe;
        u8                      bAddress = usb_pipedevice(nPipe);
        int                     bEnd = pEnd->bLocalEnd;

        /* initialize software qh state */
        qh->offset = 0;
        qh->segsize = 0;

        /* gather right source of data */
        switch (qh->type) {
        case USB_ENDPOINT_XFER_CONTROL:
                /* control transfers always start with SETUP */
                is_in = 0;
                pEnd->out_qh = qh;
                musb->bEnd0Stage = MGC_END0_START;
                pBuffer = urb->setup_packet;
                dwLength = 8;
                break;
        case USB_ENDPOINT_XFER_ISOC:
                qh->iso_idx = 0;
                qh->frame = 0;
                pBuffer = urb->transfer_buffer + urb->iso_frame_desc[0].offset;
                dwLength = urb->iso_frame_desc[0].length;
                break;
        default:                /* bulk, interrupt */
                pBuffer = urb->transfer_buffer;
                dwLength = urb->transfer_buffer_length;
        }

        DBG(4, "qh %p urb %p dev%d ep%d%s%s, hw_ep %d, %p/%d\n",
                        qh, urb, bAddress, qh->epnum,
                        is_in ? "in" : "out",
                        ({char *s; switch (qh->type) {
                        case USB_ENDPOINT_XFER_CONTROL: s = ""; break;
                        case USB_ENDPOINT_XFER_BULK:    s = "-bulk"; break;
                        case USB_ENDPOINT_XFER_ISOC:    s = "-iso"; break;
                        default:                        s = "-intr"; break;
                        }; s;}),
                        bEnd, pBuffer, dwLength);

        /* Configure endpoint */
        if (is_in || pEnd->bIsSharedFifo)
                pEnd->in_qh = qh;
        else
                pEnd->out_qh = qh;
        musb_ep_program(musb, bEnd, urb, !is_in, pBuffer, dwLength);

        /* transmit may have more work: start it when it is time */
        if (is_in)
                return;

        /* determine if the time is right for a periodic transfer */
        switch (qh->type) {
        case USB_ENDPOINT_XFER_ISOC:
        case USB_ENDPOINT_XFER_INT:
                DBG(3, "check whether there's still time for periodic Tx\n");
                qh->iso_idx = 0;
                wFrame = musb_readw(pBase, MGC_O_HDRC_FRAME);
                /* FIXME this doesn't implement that scheduling policy ...
                 * or handle framecounter wrapping
                 */
                if ((urb->transfer_flags & URB_ISO_ASAP)
                                || (wFrame >= urb->start_frame)) {
                        /* REVISIT the SOF irq handler shouldn't duplicate
                         * this code; and we don't init urb->start_frame...
                         */
                        qh->frame = 0;
                        goto start;
                } else {
                        qh->frame = urb->start_frame;
                        /* enable SOF interrupt so we can count down */
DBG(1,"SOF for %d\n", bEnd);
#if 1 // ifndef CONFIG_ARCH_DAVINCI
                        musb_writeb(pBase, MGC_O_HDRC_INTRUSBE, 0xff);
#endif
                }
                break;
        default:
start:
                DBG(4, "Start TX%d %s\n", bEnd,
                        pEnd->tx_channel ? "dma" : "pio");

                if (!pEnd->tx_channel)
                        musb_h_tx_start(pEnd);
                else if (is_cppi_enabled())
                        cppi_host_txdma_start(pEnd);
        }
}

/* caller owns controller lock, irqs are blocked */
static void
__musb_giveback(struct musb *musb, struct urb *urb, int status)
__releases(musb->Lock)
__acquires(musb->Lock)
{
        if ((urb->transfer_flags & URB_SHORT_NOT_OK)
                        && (urb->actual_length < urb->transfer_buffer_length)
                        && status == 0
                        && usb_pipein(urb->pipe))
                status = -EREMOTEIO;

        spin_lock(&urb->lock);
        urb->hcpriv = NULL;
        if (urb->status == -EINPROGRESS)
                urb->status = status;
        spin_unlock(&urb->lock);

        DBG(({ int level; switch (urb->status) {
                                case 0:
                                        level = 4;
                                        break;
                                /* common/boring faults */
                                case -EREMOTEIO:
                                case -ESHUTDOWN:
                                case -ECONNRESET:
                                case -EPIPE:
                                        level = 3;
                                        break;
                                default:
                                        level = 2;
                                        break;
                                }; level; }),
                        "complete %p (%d), dev%d ep%d%s, %d/%d\n",
                        urb, urb->status,
                        usb_pipedevice(urb->pipe),
                        usb_pipeendpoint(urb->pipe),
                        usb_pipein(urb->pipe) ? "in" : "out",
                        urb->actual_length, urb->transfer_buffer_length
                        );

        spin_unlock(&musb->Lock);
        usb_hcd_giveback_urb(musb_to_hcd(musb), urb);
        spin_lock(&musb->Lock);
}

/* for bulk/interrupt endpoints only */
static inline void musb_save_toggle(struct musb_hw_ep *ep, int is_in, struct urb *urb)
{
        struct usb_device       *udev = urb->dev;
        u16                     csr;
        void __iomem            *epio = ep->regs;
        struct musb_qh          *qh;

        /* FIXME:  the current Mentor DMA code seems to have
         * problems getting toggle correct.
         */

        if (is_in || ep->bIsSharedFifo)
                qh = ep->in_qh;
        else
                qh = ep->out_qh;

        if (!is_in) {
                csr = musb_readw(epio, MGC_O_HDRC_TXCSR);
                usb_settoggle(udev, qh->epnum, 1,
                        (csr & MGC_M_TXCSR_H_DATATOGGLE)
                                ? 1 : 0);
        } else {
                csr = musb_readw(epio, MGC_O_HDRC_RXCSR);
                usb_settoggle(udev, qh->epnum, 0,
                        (csr & MGC_M_RXCSR_H_DATATOGGLE)
                                ? 1 : 0);
        }
}

/* caller owns controller lock, irqs are blocked */
static struct musb_qh *
musb_giveback(struct musb_qh *qh, struct urb *urb, int status)
{
        int                     is_in;
        struct musb_hw_ep       *ep = qh->hw_ep;
        struct musb             *musb = ep->musb;
        int                     ready = qh->is_ready;

        if (ep->bIsSharedFifo)
                is_in = 1;
        else
                is_in = usb_pipein(urb->pipe);

        /* save toggle eagerly, for paranoia */
        switch (qh->type) {
        case USB_ENDPOINT_XFER_BULK:
        case USB_ENDPOINT_XFER_INT:
                musb_save_toggle(ep, is_in, urb);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                if (status == 0 && urb->error_count)
                        status = -EXDEV;
                break;
        }

        qh->is_ready = 0;
        __musb_giveback(musb, urb, status);
        qh->is_ready = ready;

        /* reclaim resources (and bandwidth) ASAP; deschedule it, and
         * invalidate qh as soon as list_empty(&hep->urb_list)
         */
        if (list_empty(&qh->hep->urb_list)) {
                struct list_head        *head;

                if (is_in)
                        ep->rx_reinit = 1;
                else
                        ep->tx_reinit = 1;

                /* clobber old pointers to this qh */
                if (is_in || ep->bIsSharedFifo)
                        ep->in_qh = NULL;
                else
                        ep->out_qh = NULL;
                qh->hep->hcpriv = NULL;

                switch (qh->type) {

                case USB_ENDPOINT_XFER_ISOC:
                case USB_ENDPOINT_XFER_INT:
                        /* this is where periodic bandwidth should be
                         * de-allocated if it's tracked and allocated;
                         * and where we'd update the schedule tree...
                         */
                        musb->periodic[ep->bLocalEnd] = NULL;
                        kfree(qh);
                        qh = NULL;
                        break;

                case USB_ENDPOINT_XFER_CONTROL:
                case USB_ENDPOINT_XFER_BULK:
                        /* fifo policy for these lists, except that NAKing
                         * should rotate a qh to the end (for fairness).
                         */
                        head = qh->ring.prev;
                        list_del(&qh->ring);
                        kfree(qh);
                        qh = first_qh(head);
                        break;
                }
        }
        return qh;
}

/*
 * Advance this hardware endpoint's queue, completing the specified urb and
 * advancing to either the next urb queued to that qh, or else invalidating
 * that qh and advancing to the next qh scheduled after the current one.
 *
 * Context: caller owns controller lock, irqs are blocked
 */
static void
musb_advance_schedule(struct musb *pThis, struct urb *urb,
                struct musb_hw_ep *pEnd, int is_in)
{
        struct musb_qh  *qh;

        if (is_in || pEnd->bIsSharedFifo)
                qh = pEnd->in_qh;
        else
                qh = pEnd->out_qh;
        qh = musb_giveback(qh, urb, 0);

#ifdef CONFIG_USB_INVENTRA_DMA
        /* REVISIT udelay reportedly works around issues in unmodified
         * Mentor RTL before v1.5, where it doesn't disable the pull-up
         * resisters in high speed mode.  That causes signal reflection
         * and errors because inter packet IDLE time vanishes.
         *
         * Yes, this delay makes DMA-OUT a bit slower than PIO.  But
         * without it, some devices are unusable.  But there seem to be
         * other issues too, at least on DaVinci; the delay improves
         * some full speed cases, and being DMA-coupled is strange...
         */
        if (is_dma_capable() && !is_in && pEnd->tx_channel)
                udelay(15);     /* 10 usec ~= 1x 512byte packet */
#endif

        if (qh && qh->is_ready && !list_empty(&qh->hep->urb_list)) {
                DBG(4, "... next ep%d %cX urb %p\n",
                                pEnd->bLocalEnd, is_in ? 'R' : 'T',
                                next_urb(qh));
                musb_start_urb(pThis, is_in, qh);
        }
}

static inline u16 musb_h_flush_rxfifo(struct musb_hw_ep *hw_ep, u16 csr)
{
        /* we don't want fifo to fill itself again;
         * ignore dma (various models),
         * leave toggle alone (may not have been saved yet)
         */
        csr |= MGC_M_RXCSR_FLUSHFIFO | MGC_M_RXCSR_RXPKTRDY;
        csr &= ~( MGC_M_RXCSR_H_REQPKT
                | MGC_M_RXCSR_H_AUTOREQ
                | MGC_M_RXCSR_AUTOCLEAR
                );

        /* write 2x to allow double buffering */
        musb_writew(hw_ep->regs, MGC_O_HDRC_RXCSR, csr);
        musb_writew(hw_ep->regs, MGC_O_HDRC_RXCSR, csr);

        /* flush writebuffer */
        return musb_readw(hw_ep->regs, MGC_O_HDRC_RXCSR);
}

/*
 * PIO RX for a packet (or part of it).
 */
static u8 musb_host_packet_rx(struct musb *pThis, struct urb *pUrb,
                u8 bEnd, u8 bIsochError)
{
        u16 wRxCount;
        u8 *pBuffer;
        u16 wCsr;
        u8 bDone = FALSE;
        u32                     length;
        int                     do_flush = 0;
        struct musb_hw_ep       *pEnd = pThis->aLocalEnd + bEnd;
        void __iomem            *epio = pEnd->regs;
        struct musb_qh          *qh = pEnd->in_qh;
        int                     nPipe = pUrb->pipe;
        void                    *buffer = pUrb->transfer_buffer;

        // MGC_SelectEnd(pBase, bEnd);
        wRxCount = musb_readw(epio, MGC_O_HDRC_RXCOUNT);

        /* unload FIFO */
        if (usb_pipeisoc(nPipe)) {
                int                                     status = 0;
                struct usb_iso_packet_descriptor        *d;

                if (bIsochError) {
                        status = -EILSEQ;
                        pUrb->error_count++;
                }

                d = pUrb->iso_frame_desc + qh->iso_idx;
                pBuffer = buffer + d->offset;
                length = d->length;
                if (wRxCount > length) {
                        if (status == 0) {
                                status = -EOVERFLOW;
                                pUrb->error_count++;
                        }
                        DBG(2, "** OVERFLOW %d into %d\n", wRxCount, length);
                        do_flush = 1;
                } else
                        length = wRxCount;
                pUrb->actual_length += length;
                d->actual_length = length;

                d->status = status;

                /* see if we are done */
                bDone = (++qh->iso_idx >= pUrb->number_of_packets);
        } else {
                /* non-isoch */
                pBuffer = buffer + qh->offset;
                length = pUrb->transfer_buffer_length - qh->offset;
                if (wRxCount > length) {
                        if (pUrb->status == -EINPROGRESS)
                                pUrb->status = -EOVERFLOW;
                        DBG(2, "** OVERFLOW %d into %d\n", wRxCount, length);
                        do_flush = 1;
                } else
                        length = wRxCount;
                pUrb->actual_length += length;
                qh->offset += length;

                /* see if we are done */
                bDone = (pUrb->actual_length == pUrb->transfer_buffer_length)
                        || (wRxCount < qh->maxpacket)
                        || (pUrb->status != -EINPROGRESS);
                if (bDone
                                && (pUrb->status == -EINPROGRESS)
                                && (pUrb->transfer_flags & URB_SHORT_NOT_OK)
                                && (pUrb->actual_length
                                        < pUrb->transfer_buffer_length))
                        pUrb->status = -EREMOTEIO;
        }

        musb_read_fifo(pEnd, length, pBuffer);

        wCsr = musb_readw(epio, MGC_O_HDRC_RXCSR);
        wCsr |= MGC_M_RXCSR_H_WZC_BITS;
        if (unlikely(do_flush))
                musb_h_flush_rxfifo(pEnd, wCsr);
        else {
                /* REVISIT this assumes AUTOCLEAR is never set */
                wCsr &= ~(MGC_M_RXCSR_RXPKTRDY | MGC_M_RXCSR_H_REQPKT);
                if (!bDone)
                        wCsr |= MGC_M_RXCSR_H_REQPKT;
                musb_writew(epio, MGC_O_HDRC_RXCSR, wCsr);
        }

        return bDone;
}

/* we don't always need to reinit a given side of an endpoint...
 * when we do, use tx/rx reinit routine and then construct a new CSR
 * to address data toggle, NYET, and DMA or PIO.
 *
 * it's possible that driver bugs (especially for DMA) or aborting a
 * transfer might have left the endpoint busier than it should be.
 * the busy/not-empty tests are basically paranoia.
 */
static void
musb_rx_reinit(struct musb *musb, struct musb_qh *qh, struct musb_hw_ep *ep)
{
        u16     csr;

        /* NOTE:  we know the "rx" fifo reinit never triggers for ep0.
         * That always uses tx_reinit since ep0 repurposes TX register
         * offsets; the initial SETUP packet is also a kind of OUT.
         */

        /* if programmed for Tx, put it in RX mode */
        if (ep->bIsSharedFifo) {
                csr = musb_readw(ep->regs, MGC_O_HDRC_TXCSR);
                if (csr & MGC_M_TXCSR_MODE) {
                        if (csr & MGC_M_TXCSR_FIFONOTEMPTY) {
                                /* this shouldn't happen; irq?? */
                                ERR("shared fifo not empty?\n");
                                musb_writew(ep->regs, MGC_O_HDRC_TXCSR,
                                                MGC_M_TXCSR_FLUSHFIFO);
                                musb_writew(ep->regs, MGC_O_HDRC_TXCSR,
                                                MGC_M_TXCSR_FRCDATATOG);
                        }
                }
                /* clear mode (and everything else) to enable Rx */
                musb_writew(ep->regs, MGC_O_HDRC_TXCSR, 0);

        /* scrub all previous state, clearing toggle */
        } else {
                csr = musb_readw(ep->regs, MGC_O_HDRC_RXCSR);
                if (csr & MGC_M_RXCSR_RXPKTRDY)
                        WARN("rx%d, packet/%d ready?\n", ep->bLocalEnd,
                                musb_readw(ep->regs, MGC_O_HDRC_RXCOUNT));

                musb_h_flush_rxfifo(ep, MGC_M_RXCSR_CLRDATATOG);
        }

        /* target addr and (for multipoint) hub addr/port */
        if (musb->bIsMultipoint) {
                musb_writeb(ep->target_regs, MGC_O_HDRC_RXFUNCADDR,
                        qh->addr_reg);
                musb_writeb(ep->target_regs, MGC_O_HDRC_RXHUBADDR,
                        qh->h_addr_reg);
                musb_writeb(ep->target_regs, MGC_O_HDRC_RXHUBPORT,
                        qh->h_port_reg);
        } else
                musb_writeb(musb->pRegs, MGC_O_HDRC_FADDR, qh->addr_reg);

        /* protocol/endpoint, interval/NAKlimit, i/o size */
        musb_writeb(ep->regs, MGC_O_HDRC_RXTYPE, qh->type_reg);
        musb_writeb(ep->regs, MGC_O_HDRC_RXINTERVAL, qh->intv_reg);
        /* NOTE: bulk combining rewrites high bits of maxpacket */
        musb_writew(ep->regs, MGC_O_HDRC_RXMAXP, qh->maxpacket);

        ep->rx_reinit = 0;
}


/*
 * Program an HDRC endpoint as per the given URB
 * Context: irqs blocked, controller lock held
 */
static void musb_ep_program(struct musb *pThis, u8 bEnd,
                        struct urb *pUrb, unsigned int is_out,
                        u8 * pBuffer, u32 dwLength)
{
        struct dma_controller   *pDmaController;
        struct dma_channel      *pDmaChannel;
        u8                      bDmaOk;
        void __iomem            *pBase = pThis->pRegs;
        struct musb_hw_ep       *pEnd = pThis->aLocalEnd + bEnd;
        void __iomem            *epio = pEnd->regs;
        struct musb_qh          *qh;
        u16                     wPacketSize;

        if (!is_out || pEnd->bIsSharedFifo)
                qh = pEnd->in_qh;
        else
                qh = pEnd->out_qh;

        wPacketSize = qh->maxpacket;

        DBG(3, "%s hw%d urb %p spd%d dev%d ep%d%s "
                                "h_addr%02x h_port%02x bytes %d\n",
                        is_out ? "-->" : "<--",
                        bEnd, pUrb, pUrb->dev->speed,
                        qh->addr_reg, qh->epnum, is_out ? "out" : "in",
                        qh->h_addr_reg, qh->h_port_reg,
                        dwLength);

        MGC_SelectEnd(pBase, bEnd);

        /* candidate for DMA? */
        pDmaController = pThis->pDmaController;
        if (is_dma_capable() && bEnd && pDmaController) {
                pDmaChannel = is_out ? pEnd->tx_channel : pEnd->rx_channel;
                if (!pDmaChannel) {
                        pDmaChannel = pDmaController->channel_alloc(
                                        pDmaController, pEnd, is_out);
                        if (is_out)
                                pEnd->tx_channel = pDmaChannel;
                        else
                                pEnd->rx_channel = pDmaChannel;
                }
        } else
                pDmaChannel = NULL;

        /* make sure we clear DMAEnab, autoSet bits from previous run */

        /* OUT/transmit/EP0 or IN/receive? */
        if (is_out) {
                u16     wCsr;
                u16     wIntrTxE;
                u16     wLoadCount;

                wCsr = musb_readw(epio, MGC_O_HDRC_TXCSR);

                /* disable interrupt in case we flush */
                wIntrTxE = musb_readw(pBase, MGC_O_HDRC_INTRTXE);
                musb_writew(pBase, MGC_O_HDRC_INTRTXE, wIntrTxE & ~(1 << bEnd));

                /* general endpoint setup */
                if (bEnd) {
                        u16     csr = wCsr;

                        /* ASSERT:  TXCSR_DMAENAB was already cleared */

                        /* flush all old state, set default */
                        if (csr & MGC_M_TXCSR_FIFONOTEMPTY)
                                csr |= MGC_M_TXCSR_FLUSHFIFO;
                        csr &= ~(MGC_M_TXCSR_H_NAKTIMEOUT
                                        | MGC_M_TXCSR_DMAMODE
                                        | MGC_M_TXCSR_FRCDATATOG
                                        | MGC_M_TXCSR_H_RXSTALL
                                        | MGC_M_TXCSR_H_ERROR
                                        | MGC_M_TXCSR_FIFONOTEMPTY
                                        | MGC_M_TXCSR_TXPKTRDY
                                        );
                        csr |= MGC_M_TXCSR_MODE;

                        if (usb_gettoggle(pUrb->dev,
                                        qh->epnum, 1))
                                csr |= MGC_M_TXCSR_H_WR_DATATOGGLE
                                        | MGC_M_TXCSR_H_DATATOGGLE;
                        else
                                csr |= MGC_M_TXCSR_CLRDATATOG;

                        /* twice in case of double packet buffering */
                        musb_writew(epio, MGC_O_HDRC_TXCSR, csr);
                        /* REVISIT may need to clear FLUSHFIFO ... */
                        musb_writew(epio, MGC_O_HDRC_TXCSR, csr);
                        wCsr = musb_readw(epio, MGC_O_HDRC_TXCSR);
                } else {
                        /* endpoint 0: just flush */
                        musb_writew(epio, MGC_O_HDRC_CSR0,
                                wCsr | MGC_M_CSR0_FLUSHFIFO);
                        musb_writew(epio, MGC_O_HDRC_CSR0,
                                wCsr | MGC_M_CSR0_FLUSHFIFO);
                }

                /* target addr and (for multipoint) hub addr/port */
                if (pThis->bIsMultipoint) {
                        musb_writeb(pBase,
                                MGC_BUSCTL_OFFSET(bEnd, MGC_O_HDRC_TXFUNCADDR),
                                qh->addr_reg);
                        musb_writeb(pBase,
                                MGC_BUSCTL_OFFSET(bEnd, MGC_O_HDRC_TXHUBADDR),
                                qh->h_addr_reg);
                        musb_writeb(pBase,
                                MGC_BUSCTL_OFFSET(bEnd, MGC_O_HDRC_TXHUBPORT),
                                qh->h_port_reg);
/* FIXME if !bEnd, do the same for RX ... */
                } else
                        musb_writeb(pBase, MGC_O_HDRC_FADDR, qh->addr_reg);

                /* protocol/endpoint/interval/NAKlimit */
                if (bEnd) {
                        musb_writeb(epio, MGC_O_HDRC_TXTYPE, qh->type_reg);
                        if (can_bulk_split(pThis, qh->type))
                                musb_writew(epio, MGC_O_HDRC_TXMAXP,
                                        wPacketSize
                                        | ((pEnd->wMaxPacketSizeTx /
                                                wPacketSize) - 1) << 11);
                        else
                                musb_writew(epio, MGC_O_HDRC_TXMAXP,
                                        wPacketSize);
                        musb_writeb(epio, MGC_O_HDRC_TXINTERVAL, qh->intv_reg);
                } else {
                        musb_writeb(epio, MGC_O_HDRC_NAKLIMIT0, qh->intv_reg);
                        if (pThis->bIsMultipoint)
                                musb_writeb(epio, MGC_O_HDRC_TYPE0,
                                                qh->type_reg);
                }

                if (can_bulk_split(pThis, qh->type))
                        wLoadCount = min((u32) pEnd->wMaxPacketSizeTx,
                                                dwLength);
                else
                        wLoadCount = min((u32) wPacketSize, dwLength);

#ifdef CONFIG_USB_INVENTRA_DMA
                if (pDmaChannel) {

                        /* clear previous state */
                        wCsr = musb_readw(epio, MGC_O_HDRC_TXCSR);
                        wCsr &= ~(MGC_M_TXCSR_AUTOSET
                                | MGC_M_TXCSR_DMAMODE
                                | MGC_M_TXCSR_DMAENAB);
                        wCsr |= MGC_M_TXCSR_MODE;
                        musb_writew(epio, MGC_O_HDRC_TXCSR,
                                wCsr | MGC_M_TXCSR_MODE);

                        qh->segsize = min(dwLength, pDmaChannel->dwMaxLength);

                        if (qh->segsize <= wPacketSize)
                                pDmaChannel->bDesiredMode = 0;
                        else
                                pDmaChannel->bDesiredMode = 1;


                        if (pDmaChannel->bDesiredMode == 0) {
                                wCsr &= ~(MGC_M_TXCSR_AUTOSET
                                        | MGC_M_TXCSR_DMAMODE);
                                wCsr |= (MGC_M_TXCSR_DMAENAB);
                                        // against programming guide
                        } else
                                wCsr |= (MGC_M_TXCSR_AUTOSET
                                        | MGC_M_TXCSR_DMAENAB
                                        | MGC_M_TXCSR_DMAMODE);

                        musb_writew(epio, MGC_O_HDRC_TXCSR, wCsr);

                        bDmaOk = pDmaController->channel_program(
                                        pDmaChannel, wPacketSize,
                                        pDmaChannel->bDesiredMode,
                                        pUrb->transfer_dma,
                                        qh->segsize);
                        if (bDmaOk) {
                                wLoadCount = 0;
                        } else {
                                pDmaController->channel_release(pDmaChannel);
                                if (is_out)
                                        pEnd->tx_channel = NULL;
                                else
                                        pEnd->rx_channel = NULL;
                                pDmaChannel = NULL;
                        }
                }
#endif

                /* candidate for DMA */
                if (is_cppi_enabled() && pDmaChannel) {

                        /* program endpoint CSRs first, then setup DMA.
                         * assume CPPI setup succeeds.
                         * defer enabling dma.
                         */
                        wCsr = musb_readw(epio, MGC_O_HDRC_TXCSR);
                        wCsr &= ~(MGC_M_TXCSR_AUTOSET
                                        | MGC_M_TXCSR_DMAMODE
                                        | MGC_M_TXCSR_DMAENAB);
                        wCsr |= MGC_M_TXCSR_MODE;
                        musb_writew(epio, MGC_O_HDRC_TXCSR,
                                wCsr | MGC_M_TXCSR_MODE);

                        pDmaChannel->dwActualLength = 0L;
                        qh->segsize = dwLength;

                        /* TX uses "rndis" mode automatically, but needs help
                         * to identify the zero-length-final-packet case.
                         */
                        bDmaOk = pDmaController->channel_program(
                                        pDmaChannel, wPacketSize,
                                        (pUrb->transfer_flags
                                                        & URB_ZERO_PACKET)
                                                == URB_ZERO_PACKET,
                                        pUrb->transfer_dma,
                                        qh->segsize);
                        if (bDmaOk) {
                                wLoadCount = 0;
                        } else {
                                pDmaController->channel_release(pDmaChannel);
                                pDmaChannel = pEnd->tx_channel = NULL;

                                /* REVISIT there's an error path here that
                                 * needs handling:  can't do dma, but
                                 * there's no pio buffer address...
                                 */
                        }
                }

                if (wLoadCount) {
                        /* ASSERT:  TXCSR_DMAENAB was already cleared */

                        /* PIO to load FIFO */
                        qh->segsize = wLoadCount;
                        musb_write_fifo(pEnd, wLoadCount, pBuffer);
                        wCsr = musb_readw(epio, MGC_O_HDRC_TXCSR);
                        wCsr &= ~(MGC_M_TXCSR_DMAENAB
                                | MGC_M_TXCSR_DMAMODE
                                | MGC_M_TXCSR_AUTOSET);
                        /* write CSR */
                        wCsr |= MGC_M_TXCSR_MODE;

                        if (bEnd)
                                musb_writew(epio, MGC_O_HDRC_TXCSR, wCsr);
                }

                /* re-enable interrupt */
                musb_writew(pBase, MGC_O_HDRC_INTRTXE, wIntrTxE);

        /* IN/receive */
        } else {
                u16     csr;

                if (pEnd->rx_reinit) {
                        musb_rx_reinit(pThis, qh, pEnd);

                        /* init new state: toggle and NYET, maybe DMA later */
                        if (usb_gettoggle(pUrb->dev, qh->epnum, 0))
                                csr = MGC_M_RXCSR_H_WR_DATATOGGLE
                                        | MGC_M_RXCSR_H_DATATOGGLE;
                        else
                                csr = 0;
                        if (qh->type == USB_ENDPOINT_XFER_INT)
                                csr |= MGC_M_RXCSR_DISNYET;

                } else {
                        csr = musb_readw(pEnd->regs, MGC_O_HDRC_RXCSR);

                        if (csr & (MGC_M_RXCSR_RXPKTRDY
                                        | MGC_M_RXCSR_DMAENAB
                                        | MGC_M_RXCSR_H_REQPKT))
                                ERR("broken !rx_reinit, ep%d csr %04x\n",
                                                pEnd->bLocalEnd, csr);

                        /* scrub any stale state, leaving toggle alone */
                        csr &= MGC_M_RXCSR_DISNYET;
                }

                /* kick things off */

                if (is_cppi_enabled()) {
                        /* candidate for DMA */
                        if (pDmaChannel) {
                                pDmaChannel->dwActualLength = 0L;
                                qh->segsize = dwLength;

                                /* AUTOREQ is in a DMA register */
                                musb_writew(pEnd->regs, MGC_O_HDRC_RXCSR, csr);
                                csr = musb_readw(pEnd->regs,
                                                MGC_O_HDRC_RXCSR);

                                /* unless caller treats short rx transfers as
                                 * errors, we dare not queue multiple transfers.
                                 */
                                bDmaOk = pDmaController->channel_program(
                                                pDmaChannel, wPacketSize,
                                                !(pUrb->transfer_flags
                                                        & URB_SHORT_NOT_OK),
                                                pUrb->transfer_dma,
                                                qh->segsize);
                                if (!bDmaOk) {
                                        pDmaController->channel_release(
                                                        pDmaChannel);
                                        pDmaChannel = pEnd->rx_channel = NULL;
                                } else
                                        csr |= MGC_M_RXCSR_DMAENAB;
                        }
                }

                csr |= MGC_M_RXCSR_H_REQPKT;
                DBG(7, "RXCSR%d := %04x\n", bEnd, csr);
                musb_writew(pEnd->regs, MGC_O_HDRC_RXCSR, csr);
                csr = musb_readw(pEnd->regs, MGC_O_HDRC_RXCSR);
        }
}


/*
 * Service the default endpoint (ep0) as host.
 * Return TRUE until it's time to start the status stage.
 */
static int musb_h_ep0_continue(struct musb *pThis,
                                u16 wCount, struct urb *pUrb)
{
        int                      bMore = FALSE;
        u8 *pFifoDest = NULL;
        u16 wFifoCount = 0;
        struct musb_hw_ep       *pEnd = pThis->control_ep;
        struct musb_qh          *qh = pEnd->in_qh;
        struct usb_ctrlrequest  *pRequest;

        switch (pThis->bEnd0Stage) {
        case MGC_END0_IN:
                pFifoDest = pUrb->transfer_buffer + pUrb->actual_length;
                wFifoCount = min(wCount, ((u16) (pUrb->transfer_buffer_length
                                        - pUrb->actual_length)));
                if (wFifoCount < wCount)
                        pUrb->status = -EOVERFLOW;

                musb_read_fifo(pEnd, wFifoCount, pFifoDest);

                pUrb->actual_length += wFifoCount;
                if (wCount < qh->maxpacket) {
                        /* always terminate on short read; it's
                         * rarely reported as an error.
                         */
                } else if (pUrb->actual_length <
                                pUrb->transfer_buffer_length)
                        bMore = TRUE;
                break;
        case MGC_END0_START:
                pRequest = (struct usb_ctrlrequest *) pUrb->setup_packet;

                if (!pRequest->wLength) {
                        DBG(4, "start no-DATA\n");
                        break;
                } else if (pRequest->bRequestType & USB_DIR_IN) {
                        DBG(4, "start IN-DATA\n");
                        pThis->bEnd0Stage = MGC_END0_IN;
                        bMore = TRUE;
                        break;
                } else {
                        DBG(4, "start OUT-DATA\n");
                        pThis->bEnd0Stage = MGC_END0_OUT;
                        bMore = TRUE;
                }
                /* FALLTHROUGH */
        case MGC_END0_OUT:
                wFifoCount = min(qh->maxpacket, ((u16)
                                (pUrb->transfer_buffer_length
                                - pUrb->actual_length)));

                if (wFifoCount) {
                        pFifoDest = (u8 *) (pUrb->transfer_buffer
                                        + pUrb->actual_length);
                        DBG(3, "Sending %d bytes to %p\n",
                                        wFifoCount, pFifoDest);
                        musb_write_fifo(pEnd, wFifoCount, pFifoDest);

                        pUrb->actual_length += wFifoCount;
                        bMore = TRUE;
                }
                break;
        default:
                ERR("bogus ep0 stage %d\n", pThis->bEnd0Stage);
                break;
        }

        return bMore;
}

/*
 * Handle default endpoint interrupt as host. Only called in IRQ time
 * from the LinuxIsr() interrupt service routine.
 *
 * called with controller irqlocked
 */
irqreturn_t musb_h_ep0_irq(struct musb *pThis)
{
        struct urb              *pUrb;
        u16                     wCsrVal, wCount;
        int                     status = 0;
        void __iomem            *pBase = pThis->pRegs;
        struct musb_hw_ep       *pEnd = pThis->control_ep;
        void __iomem            *epio = pEnd->regs;
        struct musb_qh          *qh = pEnd->in_qh;
        u8                      bComplete = FALSE;
        irqreturn_t             retval = IRQ_NONE;

        /* ep0 only has one queue, "in" */
        pUrb = next_urb(qh);

        MGC_SelectEnd(pBase, 0);
        wCsrVal = musb_readw(epio, MGC_O_HDRC_CSR0);
        wCount = (wCsrVal & MGC_M_CSR0_RXPKTRDY)
                        ? musb_readb(epio, MGC_O_HDRC_COUNT0)
                        : 0;

        DBG(4, "<== csr0 %04x, qh %p, count %d, urb %p, stage %d\n",
                wCsrVal, qh, wCount, pUrb, pThis->bEnd0Stage);

        /* if we just did status stage, we are done */
        if (MGC_END0_STATUS == pThis->bEnd0Stage) {
                retval = IRQ_HANDLED;
                bComplete = TRUE;
        }

        /* prepare status */
        if (wCsrVal & MGC_M_CSR0_H_RXSTALL) {
                DBG(6, "STALLING ENDPOINT\n");
                status = -EPIPE;

        } else if (wCsrVal & MGC_M_CSR0_H_ERROR) {
                DBG(2, "no response, csr0 %04x\n", wCsrVal);
                status = -EPROTO;

        } else if (wCsrVal & MGC_M_CSR0_H_NAKTIMEOUT) {
                DBG(2, "control NAK timeout\n");

                /* NOTE:  this code path would be a good place to PAUSE a
                 * control transfer, if another one is queued, so that
                 * ep0 is more likely to stay busy.
                 *
                 * if (qh->ring.next != &musb->control), then
                 * we have a candidate... NAKing is *NOT* an error
                 */
                musb_writew(epio, MGC_O_HDRC_CSR0, 0);
                retval = IRQ_HANDLED;
        }

        if (status) {
                DBG(6, "aborting\n");
                retval = IRQ_HANDLED;
                if (pUrb)
                        pUrb->status = status;
                bComplete = TRUE;

                /* use the proper sequence to abort the transfer */
                if (wCsrVal & MGC_M_CSR0_H_REQPKT) {
                        wCsrVal &= ~MGC_M_CSR0_H_REQPKT;
                        musb_writew(epio, MGC_O_HDRC_CSR0, wCsrVal);
                        wCsrVal &= ~MGC_M_CSR0_H_NAKTIMEOUT;
                        musb_writew(epio, MGC_O_HDRC_CSR0, wCsrVal);
                } else {
                        wCsrVal |= MGC_M_CSR0_FLUSHFIFO;
                        musb_writew(epio, MGC_O_HDRC_CSR0, wCsrVal);
                        musb_writew(epio, MGC_O_HDRC_CSR0, wCsrVal);
                        wCsrVal &= ~MGC_M_CSR0_H_NAKTIMEOUT;
                        musb_writew(epio, MGC_O_HDRC_CSR0, wCsrVal);
                }

                musb_writeb(epio, MGC_O_HDRC_NAKLIMIT0, 0);

                /* clear it */
                musb_writew(epio, MGC_O_HDRC_CSR0, 0);
        }

        if (unlikely(!pUrb)) {
                /* stop endpoint since we have no place for its data, this
                 * SHOULD NEVER HAPPEN! */
                ERR("no URB for end 0\n");

                musb_writew(epio, MGC_O_HDRC_CSR0, MGC_M_CSR0_FLUSHFIFO);
                musb_writew(epio, MGC_O_HDRC_CSR0, MGC_M_CSR0_FLUSHFIFO);
                musb_writew(epio, MGC_O_HDRC_CSR0, 0);

                goto done;
        }

        if (!bComplete) {
                /* call common logic and prepare response */
                if (musb_h_ep0_continue(pThis, wCount, pUrb)) {
                        /* more packets required */
                        wCsrVal = (MGC_END0_IN == pThis->bEnd0Stage)
                                ?  MGC_M_CSR0_H_REQPKT : MGC_M_CSR0_TXPKTRDY;
                } else {
                        /* data transfer complete; perform status phase */
                        if (usb_pipeout(pUrb->pipe)
                                        || !pUrb->transfer_buffer_length)
                                wCsrVal = MGC_M_CSR0_H_STATUSPKT
                                        | MGC_M_CSR0_H_REQPKT;
                        else
                                wCsrVal = MGC_M_CSR0_H_STATUSPKT
                                        | MGC_M_CSR0_TXPKTRDY;

                        /* flag status stage */
                        pThis->bEnd0Stage = MGC_END0_STATUS;

                        DBG(5, "ep0 STATUS, csr %04x\n", wCsrVal);

                }
                musb_writew(epio, MGC_O_HDRC_CSR0, wCsrVal);
                retval = IRQ_HANDLED;
        } else
                pThis->bEnd0Stage = MGC_END0_IDLE;

        /* call completion handler if done */
        if (bComplete)
                musb_advance_schedule(pThis, pUrb, pEnd, 1);
done:
        return retval;
}


#ifdef CONFIG_USB_INVENTRA_DMA

/* Host side TX (OUT) using Mentor DMA works as follows:
        submit_urb ->
                - if queue was empty, Program Endpoint
                - ... which starts DMA to fifo in mode 1 or 0

        DMA Isr (transfer complete) -> TxAvail()
                - Stop DMA (~DmaEnab)   (<--- Alert ... currently happens
                                        only in musb_cleanup_urb)
                - TxPktRdy has to be set in mode 0 or for
                        short packets in mode 1.
*/

#endif

/* Service a Tx-Available or dma completion irq for the endpoint */
void musb_host_tx(struct musb *pThis, u8 bEnd)
{
        int                     nPipe;
        u8                      bDone = FALSE;
        u16                     wTxCsrVal;
        size_t                  wLength = 0;
        u8                      *pBuffer = NULL;
        struct urb              *pUrb;
        struct musb_hw_ep       *pEnd = pThis->aLocalEnd + bEnd;
        void __iomem            *epio = pEnd->regs;
        struct musb_qh          *qh = pEnd->out_qh;
        u32                     status = 0;
        void __iomem            *pBase = pThis->pRegs;
        struct dma_channel      *dma;

        pUrb = next_urb(qh);

        MGC_SelectEnd(pBase, bEnd);
        wTxCsrVal = musb_readw(epio, MGC_O_HDRC_TXCSR);

        /* with CPPI, DMA sometimes triggers "extra" irqs */
        if (!pUrb) {
                DBG(4, "extra TX%d ready, csr %04x\n", bEnd, wTxCsrVal);
                goto finish;
        }

        nPipe = pUrb->pipe;
        dma = is_dma_capable() ? pEnd->tx_channel : NULL;
        DBG(4, "OUT/TX%d end, csr %04x%s\n", bEnd, wTxCsrVal,
                        dma ? ", dma" : "");

        /* check for errors */
        if (wTxCsrVal & MGC_M_TXCSR_H_RXSTALL) {
                /* dma was disabled, fifo flushed */
                DBG(3, "TX end %d stall\n", bEnd);

                /* stall; record URB status */
                status = -EPIPE;

        } else if (wTxCsrVal & MGC_M_TXCSR_H_ERROR) {
                /* (NON-ISO) dma was disabled, fifo flushed */
                DBG(3, "TX 3strikes on ep=%d\n", bEnd);

                status = -ETIMEDOUT;

        } else if (wTxCsrVal & MGC_M_TXCSR_H_NAKTIMEOUT) {
                DBG(6, "TX end=%d device not responding\n", bEnd);

                /* NOTE:  this code path would be a good place to PAUSE a
                 * transfer, if there's some other (nonperiodic) tx urb
                 * that could use this fifo.  (dma complicates it...)
                 *
                 * if (bulk && qh->ring.next != &musb->out_bulk), then
                 * we have a candidate... NAKing is *NOT* an error
                 */
                MGC_SelectEnd(pBase, bEnd);
                musb_writew(epio, MGC_O_HDRC_CSR0,
                                MGC_M_TXCSR_H_WZC_BITS
                                | MGC_M_TXCSR_TXPKTRDY);
                goto finish;
        }

        if (status) {
                if (dma_channel_status(dma) == MGC_DMA_STATUS_BUSY) {
                        dma->bStatus = MGC_DMA_STATUS_CORE_ABORT;
                        (void) pThis->pDmaController->channel_abort(dma);
                }

                /* do the proper sequence to abort the transfer in the
                 * usb core; the dma engine should already be stopped.
                 */
// SCRUB (TX)
                if (wTxCsrVal & MGC_M_TXCSR_FIFONOTEMPTY)
                        wTxCsrVal |= MGC_M_TXCSR_FLUSHFIFO;
                wTxCsrVal &= ~(MGC_M_TXCSR_FIFONOTEMPTY
                                | MGC_M_TXCSR_AUTOSET
                                | MGC_M_TXCSR_DMAENAB
                                | MGC_M_TXCSR_H_ERROR
                                | MGC_M_TXCSR_H_RXSTALL
                                | MGC_M_TXCSR_H_NAKTIMEOUT
                                );

                MGC_SelectEnd(pBase, bEnd);
                musb_writew(epio, MGC_O_HDRC_TXCSR, wTxCsrVal);
                /* REVISIT may need to clear FLUSHFIFO ... */
                musb_writew(epio, MGC_O_HDRC_TXCSR, wTxCsrVal);
                musb_writeb(epio, MGC_O_HDRC_TXINTERVAL, 0);

                bDone = TRUE;
        }

        /* second cppi case */
        if (dma_channel_status(dma) == MGC_DMA_STATUS_BUSY) {
                DBG(4, "extra TX%d ready, csr %04x\n", bEnd, wTxCsrVal);
                goto finish;

        }

        /* REVISIT this looks wrong... */
        if (!status || dma || usb_pipeisoc(nPipe)) {

#ifdef CONFIG_USB_INVENTRA_DMA
                /* mode 0 or last short packet)
                 * REVISIT how about ZLP?
                 */
                if ((dma->bDesiredMode == 0)
                                || (dma->dwActualLength
                                        & (qh->maxpacket - 1))) {
                        /* Send out the packet first ... */
                        MGC_SelectEnd(pBase, bEnd);
                        musb_writew(epio, MGC_O_HDRC_TXCSR,
                                        MGC_M_TXCSR_TXPKTRDY);
                }
#endif
                if (dma)
                        wLength = dma->dwActualLength;
                else
                        wLength = qh->segsize;
                qh->offset += wLength;

                if (usb_pipeisoc(nPipe)) {
                        struct usb_iso_packet_descriptor        *d;

                        d = pUrb->iso_frame_desc + qh->iso_idx;
                        d->actual_length = qh->segsize;
                        if (++qh->iso_idx >= pUrb->number_of_packets) {
                                bDone = TRUE;
                        } else if (!dma) {
                                d++;
                                pBuffer = pUrb->transfer_buffer + d->offset;
                                wLength = d->length;
                        }
                } else if (dma) {
                        bDone = TRUE;
                } else {
                        /* see if we need to send more data, or ZLP */
                        if (qh->segsize < qh->maxpacket)
                                bDone = TRUE;
                        else if (qh->offset == pUrb->transfer_buffer_length
                                        && !(pUrb-> transfer_flags
                                                        & URB_ZERO_PACKET))
                                bDone = TRUE;
                        if (!bDone) {
                                pBuffer = pUrb->transfer_buffer
                                                + qh->offset;
                                wLength = pUrb->transfer_buffer_length
                                                - qh->offset;
                        }
                }
        }

        /* urb->status != -EINPROGRESS means request has been faulted,
         * so we must abort this transfer after cleanup
         */
        if (pUrb->status != -EINPROGRESS) {
                bDone = TRUE;
                if (status == 0)
                        status = pUrb->status;
        }

        if (bDone) {
                /* set status */
                pUrb->status = status;
                pUrb->actual_length = qh->offset;
                musb_advance_schedule(pThis, pUrb, pEnd, USB_DIR_OUT);

        } else if (!(wTxCsrVal & MGC_M_TXCSR_DMAENAB)) {
                // WARN_ON(!pBuffer);

                /* REVISIT:  some docs say that when pEnd->tx_double_buffered,
                 * (and presumably, fifo is not half-full) we should write TWO
                 * packets before updating TXCSR ... other docs disagree ...
                 */
                /* PIO:  start next packet in this URB */
                wLength = min(qh->maxpacket, (u16) wLength);
                musb_write_fifo(pEnd, wLength, pBuffer);
                qh->segsize = wLength;

                MGC_SelectEnd(pBase, bEnd);
                musb_writew(epio, MGC_O_HDRC_TXCSR,
                                MGC_M_TXCSR_H_WZC_BITS | MGC_M_TXCSR_TXPKTRDY);
        } else
                DBG(1, "not complete, but dma enabled?\n");

finish:
        return;
}


#ifdef CONFIG_USB_INVENTRA_DMA

/* Host side RX (IN) using Mentor DMA works as follows:
        submit_urb ->
                - if queue was empty, ProgramEndpoint
                - first IN token is sent out (by setting ReqPkt)
        LinuxIsr -> RxReady()
        /\      => first packet is received
        |       - Set in mode 0 (DmaEnab, ~ReqPkt)
        |               -> DMA Isr (transfer complete) -> RxReady()
        |                   - Ack receive (~RxPktRdy), turn off DMA (~DmaEnab)
        |                   - if urb not complete, send next IN token (ReqPkt)
        |                          |            else complete urb.
        |                          |
        ---------------------------
 *
 * Nuances of mode 1:
 *      For short packets, no ack (+RxPktRdy) is sent automatically
 *      (even if AutoClear is ON)
 *      For full packets, ack (~RxPktRdy) and next IN token (+ReqPkt) is sent
 *      automatically => major problem, as collecting the next packet becomes
 *      difficult. Hence mode 1 is not used.
 *
 * REVISIT
 *      All we care about at this driver level is that
 *       (a) all URBs terminate with REQPKT cleared and fifo(s) empty;
 *       (b) termination conditions are: short RX, or buffer full;
 *       (c) fault modes include
 *           - iff URB_SHORT_NOT_OK, short RX status is -EREMOTEIO.
 *             (and that endpoint's dma queue stops immediately)
 *           - overflow (full, PLUS more bytes in the terminal packet)
 *
 *      So for example, usb-storage sets URB_SHORT_NOT_OK, and would
 *      thus be a great candidate for using mode 1 ... for all but the
 *      last packet of one URB's transfer.
 */

#endif

/*
 * Service an RX interrupt for the given IN endpoint; docs cover bulk, iso,
 * and high-bandwidth IN transfer cases.
 */
void musb_host_rx(struct musb *pThis, u8 bEnd)
{
        struct urb              *pUrb;
        struct musb_hw_ep       *pEnd = pThis->aLocalEnd + bEnd;
        void __iomem            *epio = pEnd->regs;
        struct musb_qh          *qh = pEnd->in_qh;
        size_t                  xfer_len;
        void __iomem            *pBase = pThis->pRegs;
        int                     nPipe;
        u16                     wRxCsrVal, wVal;
        u8                      bIsochError = FALSE;
        u8                      bDone = FALSE;
        u32                     status;
        struct dma_channel      *dma;

        MGC_SelectEnd(pBase, bEnd);

        pUrb = next_urb(qh);
        dma = is_dma_capable() ? pEnd->rx_channel : NULL;
        status = 0;
        xfer_len = 0;

        wVal = wRxCsrVal = musb_readw(epio, MGC_O_HDRC_RXCSR);

        if (unlikely(!pUrb)) {
                /* REVISIT -- THIS SHOULD NEVER HAPPEN ... but, at least
                 * usbtest #11 (unlinks) triggers it regularly, sometimes
                 * with fifo full.  (Only with DMA??)
                 */
                DBG(3, "BOGUS RX%d ready, csr %04x, count %d\n", bEnd, wVal,
                        musb_readw(epio, MGC_O_HDRC_RXCOUNT));
                musb_h_flush_rxfifo(pEnd, MGC_M_RXCSR_CLRDATATOG);
                return;
        }

        nPipe = pUrb->pipe;

        DBG(5, "<== hw %d rxcsr %04x, urb actual %d (+dma %zd)\n",
                bEnd, wRxCsrVal, pUrb->actual_length,
                dma ? dma->dwActualLength : 0);

        /* check for errors, concurrent stall & unlink is not really
         * handled yet! */
        if (wRxCsrVal & MGC_M_RXCSR_H_RXSTALL) {
                DBG(3, "RX end %d STALL\n", bEnd);

                /* stall; record URB status */
                status = -EPIPE;

        } else if (wRxCsrVal & MGC_M_RXCSR_H_ERROR) {
                DBG(3, "end %d RX proto error\n", bEnd);

                status = -EPROTO;
                musb_writeb(epio, MGC_O_HDRC_RXINTERVAL, 0);

        } else if (wRxCsrVal & MGC_M_RXCSR_DATAERROR) {

                if (USB_ENDPOINT_XFER_ISOC != qh->type) {
                        /* NOTE this code path would be a good place to PAUSE a
                         * transfer, if there's some other (nonperiodic) rx urb
                         * that could use this fifo.  (dma complicates it...)
                         *
                         * if (bulk && qh->ring.next != &musb->in_bulk), then
                         * we have a candidate... NAKing is *NOT* an error
                         */
                        DBG(6, "RX end %d NAK timeout\n", bEnd);
                        MGC_SelectEnd(pBase, bEnd);
                        musb_writew(epio, MGC_O_HDRC_RXCSR,
                                        MGC_M_RXCSR_H_WZC_BITS
                                        | MGC_M_RXCSR_H_REQPKT);

                        goto finish;
                } else {
                        DBG(4, "RX end %d ISO data error\n", bEnd);
                        /* packet error reported later */
                        bIsochError = TRUE;
                }
        }

        /* faults abort the transfer */
        if (status) {
                /* clean up dma and collect transfer count */
                if (dma_channel_status(dma) == MGC_DMA_STATUS_BUSY) {
                        dma->bStatus = MGC_DMA_STATUS_CORE_ABORT;
                        (void) pThis->pDmaController->channel_abort(dma);
                        xfer_len = dma->dwActualLength;
                }
                musb_h_flush_rxfifo(pEnd, 0);
                musb_writeb(epio, MGC_O_HDRC_RXINTERVAL, 0);
                bDone = TRUE;
                goto finish;
        }

        if (unlikely(dma_channel_status(dma) == MGC_DMA_STATUS_BUSY)) {
                /* SHOULD NEVER HAPPEN ... but at least DaVinci has done it */
                ERR("RX%d dma busy, csr %04x\n", bEnd, wRxCsrVal);
                goto finish;
        }

        /* thorough shutdown for now ... given more precise fault handling
         * and better queueing support, we might keep a DMA pipeline going
         * while processing this irq for earlier completions.
         */

        /* FIXME this is _way_ too much in-line logic for Mentor DMA */

#ifndef CONFIG_USB_INVENTRA_DMA
        if (wRxCsrVal & MGC_M_RXCSR_H_REQPKT)  {
                /* REVISIT this happened for a while on some short reads...
                 * the cleanup still needs investigation... looks bad...
                 * and also duplicates dma cleanup code above ... plus,
                 * shouldn't this be the "half full" double buffer case?
                 */
                if (dma_channel_status(dma) == MGC_DMA_STATUS_BUSY) {
                        dma->bStatus = MGC_DMA_STATUS_CORE_ABORT;
                        (void) pThis->pDmaController->channel_abort(dma);
                        xfer_len = dma->dwActualLength;
                        bDone = TRUE;
                }

                DBG(2, "RXCSR%d %04x, reqpkt, len %zd%s\n", bEnd, wRxCsrVal,
                                xfer_len, dma ? ", dma" : "");
                wRxCsrVal &= ~MGC_M_RXCSR_H_REQPKT;

                MGC_SelectEnd(pBase, bEnd);
                musb_writew(epio, MGC_O_HDRC_RXCSR,
                                MGC_M_RXCSR_H_WZC_BITS | wRxCsrVal);
        }
#endif
        if (dma && (wRxCsrVal & MGC_M_RXCSR_DMAENAB)) {
                xfer_len = dma->dwActualLength;

                wVal &= ~(MGC_M_RXCSR_DMAENAB
                        | MGC_M_RXCSR_H_AUTOREQ
                        | MGC_M_RXCSR_AUTOCLEAR
                        | MGC_M_RXCSR_RXPKTRDY);
                musb_writew(pEnd->regs, MGC_O_HDRC_RXCSR, wVal);

#ifdef CONFIG_USB_INVENTRA_DMA
                pUrb->actual_length += xfer_len;
                qh->offset += xfer_len;

                /* bDone if pUrb buffer is full or short packet is recd */
                bDone = (pUrb->actual_length >= pUrb->transfer_buffer_length)
                        || (dma->dwActualLength & (qh->maxpacket - 1));

                /* send IN token for next packet, without AUTOREQ */
                if (!bDone) {
                        wVal |= MGC_M_RXCSR_H_REQPKT;
                        musb_writew(epio, MGC_O_HDRC_RXCSR,
                                MGC_M_RXCSR_H_WZC_BITS | wVal);
                }

                DBG(4, "ep %d dma %s, rxcsr %04x, rxcount %d\n", bEnd,
                        bDone ? "off" : "reset",
                        musb_readw(epio, MGC_O_HDRC_RXCSR),
                        musb_readw(epio, MGC_O_HDRC_RXCOUNT));
#else
                bDone = TRUE;
#endif
        } else if (pUrb->status == -EINPROGRESS) {
                /* if no errors, be sure a packet is ready for unloading */
                if (unlikely(!(wRxCsrVal & MGC_M_RXCSR_RXPKTRDY))) {
                        status = -EPROTO;
                        ERR("Rx interrupt with no errors or packet!\n");

                        // FIXME this is another "SHOULD NEVER HAPPEN"

// SCRUB (RX)
                        /* do the proper sequence to abort the transfer */
                        MGC_SelectEnd(pBase, bEnd);
                        wVal &= ~MGC_M_RXCSR_H_REQPKT;
                        musb_writew(epio, MGC_O_HDRC_RXCSR, wVal);
                        goto finish;
                }

                /* we are expecting IN packets */
#ifdef CONFIG_USB_INVENTRA_DMA
                if (dma) {
                        struct dma_controller   *c;
                        u16                     wRxCount;
                        int                     status;

                        wRxCount = musb_readw(epio, MGC_O_HDRC_RXCOUNT);

                        DBG(2, "RX%d count %d, buffer 0x%x len %d/%d\n",
                                        bEnd, wRxCount,
                                        pUrb->transfer_dma
                                                + pUrb->actual_length,
                                        qh->offset,
                                        pUrb->transfer_buffer_length);

                        c = pThis->pDmaController;

                        dma->bDesiredMode = 0;
#ifdef USE_MODE1
                        /* because of the issue below, mode 1 will
                         * only rarely behave with correct semantics.
                         */
                        if ((pUrb->transfer_flags &
                                                URB_SHORT_NOT_OK)
                                && (pUrb->transfer_buffer_length -
                                                pUrb->actual_length)
                                        > qh->maxpacket)
                                dma->bDesiredMode = 1;
#endif

/* Disadvantage of using mode 1:
 *      It's basically usable only for mass storage class; essentially all
 *      other protocols also terminate transfers on short packets.
 *
 * Details:
 *      An extra IN token is sent at the end of the transfer (due to AUTOREQ)
 *      If you try to use mode 1 for (transfer_buffer_length - 512), and try
 *      to use the extra IN token to grab the last packet using mode 0, then
 *      the problem is that you cannot be sure when the device will send the
 *      last packet and RxPktRdy set. Sometimes the packet is recd too soon
 *      such that it gets lost when RxCSR is re-set at the end of the mode 1
 *      transfer, while sometimes it is recd just a little late so that if you
 *      try to configure for mode 0 soon after the mode 1 transfer is
 *      completed, you will find rxcount 0. Okay, so you might think why not
 *      wait for an interrupt when the pkt is recd. Well, you won't get any!
 */

                        wVal = musb_readw(epio, MGC_O_HDRC_RXCSR);
                        wVal &= ~MGC_M_RXCSR_H_REQPKT;

                        if (dma->bDesiredMode == 0)
                                wVal &= ~MGC_M_RXCSR_H_AUTOREQ;
                        else
                                wVal |= MGC_M_RXCSR_H_AUTOREQ;
                        wVal |= MGC_M_RXCSR_AUTOCLEAR | MGC_M_RXCSR_DMAENAB;

                        musb_writew(epio, MGC_O_HDRC_RXCSR,
                                MGC_M_RXCSR_H_WZC_BITS | wVal);

                        /* REVISIT if when actual_length != 0,
                         * transfer_buffer_length needs to be
                         * adjusted first...
                         */
                        status = c->channel_program(
                                dma, qh->maxpacket,
                                dma->bDesiredMode,
                                pUrb->transfer_dma
                                        + pUrb->actual_length,
                                (dma->bDesiredMode == 0)
                                        ? wRxCount
                                        : pUrb->transfer_buffer_length);

                        if (!status) {
                                c->channel_release(dma);
                                dma = pEnd->rx_channel = NULL;
                                /* REVISIT reset CSR */
                        }
                }
#endif  /* Mentor DMA */

                if (!dma) {
                        bDone = musb_host_packet_rx(pThis, pUrb,
                                        bEnd, bIsochError);
                        DBG(6, "read %spacket\n", bDone ? "last " : "");
                }
        }

finish:
        pUrb->actual_length += xfer_len;
        qh->offset += xfer_len;
        if (bDone) {
                if (pUrb->status == -EINPROGRESS)
                        pUrb->status = status;
                musb_advance_schedule(pThis, pUrb, pEnd, USB_DIR_IN);
        }
}

/* schedule nodes correspond to peripheral endpoints, like an OHCI QH.
 * the software schedule associates multiple such nodes with a given
 * host side hardware endpoint + direction; scheduling may activate
 * that hardware endpoint.
 */
static int musb_schedule(
        struct musb             *musb,
        struct musb_qh          *qh,
        int                     is_in)
{
        int                     idle;
        int                     wBestDiff;
        int                     nBestEnd, nEnd;
        struct musb_hw_ep       *hw_ep = NULL;
        struct list_head        *head = NULL;

        /* use fixed hardware for control and bulk */
        switch (qh->type) {
        case USB_ENDPOINT_XFER_CONTROL:
                head = &musb->control;
                hw_ep = musb->control_ep;
                break;
        case USB_ENDPOINT_XFER_BULK:
                hw_ep = musb->bulk_ep;
                if (is_in)
                        head = &musb->in_bulk;
                else
                        head = &musb->out_bulk;
                break;
        }
        if (head) {
                idle = list_empty(head);
                list_add_tail(&qh->ring, head);
                goto success;
        }

        /* else, periodic transfers get muxed to other endpoints */

        /* FIXME this doesn't consider direction, so it can only
         * work for one half of the endpoint hardware, and assumes
         * the previous cases handled all non-shared endpoints...
         */

        /* we know this qh hasn't been scheduled, so all we need to do
         * is choose which hardware endpoint to put it on ...
         *
         * REVISIT what we really want here is a regular schedule tree
         * like e.g. OHCI uses, but for now musb->periodic is just an
         * array of the _single_ logical endpoint associated with a
         * given physical one (identity mapping logical->physical).
         *
         * that simplistic approach makes TT scheduling a lot simpler;
         * there is none, and thus none of its complexity...
         */
        wBestDiff = 4096;
        nBestEnd = -1;

        for (nEnd = 1; nEnd < musb->bEndCount; nEnd++) {
                int     diff;

                if (musb->periodic[nEnd])
                        continue;
                hw_ep = &musb->aLocalEnd[nEnd];
                if (hw_ep == musb->bulk_ep)
                        continue;

                if (is_in)
                        diff = hw_ep->wMaxPacketSizeRx - qh->maxpacket;
                else
                        diff = hw_ep->wMaxPacketSizeTx - qh->maxpacket;

                if (diff > 0 && wBestDiff > diff) {
                        wBestDiff = diff;
                        nBestEnd = nEnd;
                }
        }
        if (nBestEnd < 0)
                return -ENOSPC;

        idle = 1;
        hw_ep = musb->aLocalEnd + nBestEnd;
        musb->periodic[nBestEnd] = qh;
        DBG(4, "qh %p periodic slot %d\n", qh, nBestEnd);
success:
        qh->hw_ep = hw_ep;
        qh->hep->hcpriv = qh;
        if (idle)
                musb_start_urb(musb, is_in, qh);
        return 0;
}

static int musb_urb_enqueue(
        struct usb_hcd                  *hcd,
        struct usb_host_endpoint        *hep,
        struct urb                      *urb,
        gfp_t                           mem_flags)
{
        unsigned long                   flags;
        struct musb                     *musb = hcd_to_musb(hcd);
        struct musb_qh                  *qh = hep->hcpriv;
        struct usb_endpoint_descriptor  *epd = &hep->desc;
        int                             status;
        unsigned                        type_reg;
        unsigned                        interval;

        /* host role must be active */
        if (!is_host_active(musb) || !musb->is_active)
                return -ENODEV;

        /* DMA mapping was already done, if needed, and this urb is on
         * hep->urb_list ... so there's little to do unless hep wasn't
         * yet scheduled onto a live qh.
         *
         * REVISIT best to keep hep->hcpriv valid until the endpoint gets
         * disabled, testing for empty qh->ring and avoiding qh setup costs
         * except for the first urb queued after a config change.
         */
        if (qh) {
                urb->hcpriv = qh;
                return 0;
        }

        /* Allocate and initialize qh, minimizing the work done each time
         * hw_ep gets reprogrammed, or with irqs blocked.  Then schedule it.
         *
         * REVISIT consider a dedicated qh kmem_cache, so it's harder
         * for bugs in other kernel code to break this driver...
         */
        qh = kzalloc(sizeof *qh, mem_flags);
        if (!qh)
                return -ENOMEM;

        qh->hep = hep;
        qh->dev = urb->dev;
        INIT_LIST_HEAD(&qh->ring);
        qh->is_ready = 1;

        qh->maxpacket = le16_to_cpu(epd->wMaxPacketSize);

        /* no high bandwidth support yet */
        if (qh->maxpacket & ~0x7ff) {
                status = -EMSGSIZE;
                goto done;
        }

        qh->epnum = epd->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
        qh->type = epd->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;

        /* NOTE: urb->dev->devnum is wrong during SET_ADDRESS */
        qh->addr_reg = (u8) usb_pipedevice(urb->pipe);

        /* precompute rxtype/txtype/type0 register */
        type_reg = (qh->type << 4) | qh->epnum;
        switch (urb->dev->speed) {
        case USB_SPEED_LOW:
                type_reg |= 0xc0;
                break;
        case USB_SPEED_FULL:
                type_reg |= 0x80;
                break;
        default:
                type_reg |= 0x40;
        }
        qh->type_reg = type_reg;

        /* precompute rxinterval/txinterval register */
        interval = min((u8)16, epd->bInterval); /* log encoding */
        switch (qh->type) {
        case USB_ENDPOINT_XFER_INT:
                /* fullspeed uses linear encoding */
                if (USB_SPEED_FULL == urb->dev->speed) {
                        interval = epd->bInterval;
                        if (!interval)
                                interval = 1;
                }
                /* FALLTHROUGH */
        case USB_ENDPOINT_XFER_ISOC:
                /* iso always uses log encoding */
                break;
        default:
                /* REVISIT we actually want to use NAK limits, hinting to the
                 * transfer scheduling logic to try some other qh, e.g. try
                 * for 2 msec first:
                 *
                 * interval = (USB_SPEED_HIGH == pUrb->dev->speed) ? 16 : 2;
                 *
                 * The downside of disabling this is that transfer scheduling
                 * gets VERY unfair for nonperiodic transfers; a misbehaving
                 * peripheral could make that hurt.  Or for reads, one that's
                 * perfectly normal:  network and other drivers keep reads
                 * posted at all times, having one pending for a week should
                 * be perfectly safe.
                 *
                 * The upside of disabling it is avoidng transfer scheduling
                 * code to put this aside for while.
                 */
                interval = 0;
        }
        qh->intv_reg = interval;

        /* precompute addressing for external hub/tt ports */
        if (musb->bIsMultipoint) {
                struct usb_device       *parent = urb->dev->parent;

                if (parent != hcd->self.root_hub) {
                        qh->h_addr_reg = (u8) parent->devnum;

                        /* set up tt info if needed */
                        if (urb->dev->tt) {
                                qh->h_port_reg = (u8) urb->dev->ttport;
                                qh->h_addr_reg |= 0x80;
                        }
                }
        }

        /* invariant: hep->hcpriv is null OR the qh that's already scheduled.
         * until we get real dma queues (with an entry for each urb/buffer),
         * we only have work to do in the former case.
         */
        spin_lock_irqsave(&musb->Lock, flags);
        if (hep->hcpriv) {
                /* some concurrent activity submitted another urb to hep...
                 * odd, rare, error prone, but legal.
                 */
                kfree(qh);
                status = 0;
        } else
                status = musb_schedule(musb, qh,
                                epd->bEndpointAddress & USB_ENDPOINT_DIR_MASK);

        if (status == 0) {
                urb->hcpriv = qh;
                /* FIXME set urb->start_frame for iso/intr, it's tested in
                 * musb_start_urb(), but otherwise only konicawc cares ...
                 */
        }
        spin_unlock_irqrestore(&musb->Lock, flags);

done:
        if (status != 0)
                kfree(qh);
        return status;
}


/*
 * abort a transfer that's at the head of a hardware queue.
 * called with controller locked, irqs blocked
 * that hardware queue advances to the next transfer, unless prevented
 */
static int musb_cleanup_urb(struct urb *urb, struct musb_qh *qh, int is_in)
{
        struct musb_hw_ep       *ep = qh->hw_ep;
        void __iomem            *epio = ep->regs;
        unsigned                hw_end = ep->bLocalEnd;
        void __iomem            *regs = ep->musb->pRegs;
        u16                     csr;
        int                     status = 0;

        MGC_SelectEnd(regs, hw_end);

        if (is_dma_capable()) {
                struct dma_channel      *dma;

                dma = is_in ? ep->rx_channel : ep->tx_channel;
                if (dma) {
                        status = ep->musb->pDmaController->channel_abort(dma);
                        DBG(status ? 1 : 3,
                                "abort %cX%d DMA for urb %p --> %d\n",
                                is_in ? 'R' : 'T', ep->bLocalEnd,
                                urb, status);
                        urb->actual_length += dma->dwActualLength;
                }
        }

        /* turn off DMA requests, discard state, stop polling ... */
        if (is_in) {
                /* giveback saves bulk toggle */
                csr = musb_h_flush_rxfifo(ep, 0);

                /* REVISIT we still get an irq; should likely clear the
                 * endpoint's irq status here to avoid bogus irqs.
                 * clearing that status is platform-specific...
                 */
        } else {
// SCRUB (TX)
                csr = musb_readw(epio, MGC_O_HDRC_TXCSR);
                if (csr & MGC_M_TXCSR_FIFONOTEMPTY)
                        csr |= MGC_M_TXCSR_FLUSHFIFO;
                csr &= ~( MGC_M_TXCSR_AUTOSET
                        | MGC_M_TXCSR_DMAENAB
                        | MGC_M_TXCSR_H_RXSTALL
                        | MGC_M_TXCSR_H_NAKTIMEOUT
                        | MGC_M_TXCSR_H_ERROR
                        | MGC_M_TXCSR_FIFONOTEMPTY
                        );
                musb_writew(epio, MGC_O_HDRC_TXCSR, csr);
                /* REVISIT may need to clear FLUSHFIFO ... */
                musb_writew(epio, MGC_O_HDRC_TXCSR, csr);
                /* flush cpu writebuffer */
                csr = musb_readw(epio, MGC_O_HDRC_TXCSR);
        }
        if (status == 0)
                musb_advance_schedule(ep->musb, urb, ep, is_in);
        return status;
}

static int musb_urb_dequeue(struct usb_hcd *hcd, struct urb *urb)
{
        struct musb             *musb = hcd_to_musb(hcd);
        struct musb_qh          *qh;
        struct list_head        *sched;
        struct urb              *tmp;
        unsigned long           flags;
        int                     status = -ENOENT;

        DBG(4, "urb=%p, dev%d ep%d%s\n", urb,
                        usb_pipedevice(urb->pipe),
                        usb_pipeendpoint(urb->pipe),
                        usb_pipein(urb->pipe) ? "in" : "out");

        spin_lock_irqsave(&musb->Lock, flags);

        /* make sure the urb is still queued and not completed */
        spin_lock(&urb->lock);
        qh = urb->hcpriv;
        if (qh) {
                struct usb_host_endpoint        *hep;

                hep = qh->hep;
                list_for_each_entry(tmp, &hep->urb_list, urb_list) {
                        if (urb == tmp) {
                                status = 0;
                                break;
                        }
                }
        }
        spin_unlock(&urb->lock);
        if (status)
                goto done;

        /* Any URB not actively programmed into endpoint hardware can be
         * immediately given back.  Such an URB must be at the head of its
         * endpoint queue, unless someday we get real DMA queues.  And even
         * then, it might not be known to the hardware...
         *
         * Otherwise abort current transfer, pending dma, etc.; urb->status
         * has already been updated.  This is a synchronous abort; it'd be
         * OK to hold off until after some IRQ, though.
         */
        if (!qh->is_ready || urb->urb_list.prev != &qh->hep->urb_list)
                status = -EINPROGRESS;
        else {
                switch (qh->type) {
                case USB_ENDPOINT_XFER_CONTROL:
                        sched = &musb->control;
                        break;
                case USB_ENDPOINT_XFER_BULK:
                        if (usb_pipein(urb->pipe))
                                sched = &musb->in_bulk;
                        else
                                sched = &musb->out_bulk;
                        break;
                default:
                        /* REVISIT when we get a schedule tree, periodic
                         * transfers won't always be at the head of a
                         * singleton queue...
                         */
                        sched = NULL;
                        break;
                }
        }

        /* NOTE:  qh is invalid unless !list_empty(&hep->urb_list) */
        if (status < 0 || (sched && qh != first_qh(sched))) {
                int     ready = qh->is_ready;

                status = 0;
                qh->is_ready = 0;
                __musb_giveback(musb, urb, 0);
                qh->is_ready = ready;
        } else
                status = musb_cleanup_urb(urb, qh, urb->pipe & USB_DIR_IN);
done:
        spin_unlock_irqrestore(&musb->Lock, flags);
        return status;
}

/* disable an endpoint */
static void
musb_h_disable(struct usb_hcd *hcd, struct usb_host_endpoint *hep)
{
        u8                      epnum = hep->desc.bEndpointAddress;
        unsigned long           flags;
        struct musb             *musb = hcd_to_musb(hcd);
        u8                      is_in = epnum & USB_DIR_IN;
        struct musb_qh          *qh = hep->hcpriv;
        struct urb              *urb, *tmp;
        struct list_head        *sched;

        if (!qh)
                return;

        spin_lock_irqsave(&musb->Lock, flags);

        switch (qh->type) {
        case USB_ENDPOINT_XFER_CONTROL:
                sched = &musb->control;
                break;
        case USB_ENDPOINT_XFER_BULK:
                if (is_in)
                        sched = &musb->in_bulk;
                else
                        sched = &musb->out_bulk;
                break;
        default:
                /* REVISIT when we get a schedule tree, periodic transfers
                 * won't always be at the head of a singleton queue...
                 */
                sched = NULL;
                break;
        }

        /* NOTE:  qh is invalid unless !list_empty(&hep->urb_list) */

        /* kick first urb off the hardware, if needed */
        qh->is_ready = 0;
        if (!sched || qh == first_qh(sched)) {
                urb = next_urb(qh);

                /* make software (then hardware) stop ASAP */
                spin_lock(&urb->lock);
                if (urb->status == -EINPROGRESS)
                        urb->status = -ESHUTDOWN;
                spin_unlock(&urb->lock);

                /* cleanup */
                musb_cleanup_urb(urb, qh, urb->pipe & USB_DIR_IN);
        } else
                urb = NULL;

        /* then just nuke all the others */
        list_for_each_entry_safe_from(urb, tmp, &hep->urb_list, urb_list)
                musb_giveback(qh, urb, -ESHUTDOWN);

        spin_unlock_irqrestore(&musb->Lock, flags);
}

static int musb_h_get_frame_number(struct usb_hcd *hcd)
{
        struct musb     *musb = hcd_to_musb(hcd);

        return musb_readw(musb->pRegs, MGC_O_HDRC_FRAME);
}

static int musb_h_start(struct usb_hcd *hcd)
{
        struct musb     *musb = hcd_to_musb(hcd);

        /* NOTE: musb_start() is called when the hub driver turns
         * on port power, or when (OTG) peripheral starts.
         */
        hcd->state = HC_STATE_RUNNING;
        musb->port1_status = 0;
        return 0;
}

static void musb_h_stop(struct usb_hcd *hcd)
{
        musb_stop(hcd_to_musb(hcd));
        hcd->state = HC_STATE_HALT;
}

static int musb_bus_suspend(struct usb_hcd *hcd)
{
        struct musb     *musb = hcd_to_musb(hcd);

        if (is_host_active(musb) && musb->is_active)
                return -EBUSY;
        else
                return 0;
}

static int musb_bus_resume(struct usb_hcd *hcd)
{
        /* resuming child port does the work */
        return 0;
}

const struct hc_driver musb_hc_driver = {
        .description            = "musb-hcd",
        .product_desc           = "MUSB HDRC host driver",
        .hcd_priv_size          = sizeof (struct musb),
        .flags                  = HCD_USB2 | HCD_MEMORY,

        /* not using irq handler or reset hooks from usbcore, since
         * those must be shared with peripheral code for OTG configs
         */

        .start                  = musb_h_start,
        .stop                   = musb_h_stop,

        .get_frame_number       = musb_h_get_frame_number,

        .urb_enqueue            = musb_urb_enqueue,
        .urb_dequeue            = musb_urb_dequeue,
        .endpoint_disable       = musb_h_disable,

        .hub_status_data        = musb_hub_status_data,
        .hub_control            = musb_hub_control,
        .bus_suspend            = musb_bus_suspend,
        .bus_resume             = musb_bus_resume,
//      .start_port_reset       = NULL,
//      .hub_irq_enable         = NULL,
};