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at91_udc.c

/*
 * at91_udc -- driver for at91-series USB peripheral controller
 *
 * Copyright (C) 2004 by Thomas Rathbone
 * Copyright (C) 2005 by HP Labs
 * Copyright (C) 2005 by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA  02111-1307, USA.
 */

#undef      DEBUG
#undef      VERBOSE
#undef      PACKET_TRACE

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/clk.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

#include <asm/byteorder.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/system.h>
#include <asm/mach-types.h>

#include <asm/arch/gpio.h>
#include <asm/arch/board.h>
#include <asm/arch/cpu.h>
#include <asm/arch/at91sam9261_matrix.h>

#include "at91_udc.h"


/*
 * This controller is simple and PIO-only.  It's used in many AT91-series
 * full speed USB controllers, including the at91rm9200 (arm920T, with MMU),
 * at91sam926x (arm926ejs, with MMU), and several no-mmu versions.
 *
 * This driver expects the board has been wired with two GPIOs suppporting
 * a VBUS sensing IRQ, and a D+ pullup.  (They may be omitted, but the
 * testing hasn't covered such cases.)
 *
 * The pullup is most important (so it's integrated on sam926x parts).  It
 * provides software control over whether the host enumerates the device.
 *
 * The VBUS sensing helps during enumeration, and allows both USB clocks
 * (and the transceiver) to stay gated off until they're necessary, saving
 * power.  During USB suspend, the 48 MHz clock is gated off in hardware;
 * it may also be gated off by software during some Linux sleep states.
 */

#define     DRIVER_VERSION    "3 May 2006"

static const char driver_name [] = "at91_udc";
static const char ep0name[] = "ep0";


#define at91_udp_read(dev, reg) \
      __raw_readl((dev)->udp_baseaddr + (reg))
#define at91_udp_write(dev, reg, val) \
      __raw_writel((val), (dev)->udp_baseaddr + (reg))

/*-------------------------------------------------------------------------*/

#ifdef CONFIG_USB_GADGET_DEBUG_FILES

#include <linux/seq_file.h>

static const char debug_filename[] = "driver/udc";

#define FOURBITS "%s%s%s%s"
#define EIGHTBITS FOURBITS FOURBITS

static void proc_ep_show(struct seq_file *s, struct at91_ep *ep)
{
      static char       *types[] = {
            "control", "out-iso", "out-bulk", "out-int",
            "BOGUS",   "in-iso",  "in-bulk",  "in-int"};

      u32               csr;
      struct at91_request     *req;
      unsigned long     flags;

      local_irq_save(flags);

      csr = __raw_readl(ep->creg);

      /* NOTE:  not collecting per-endpoint irq statistics... */

      seq_printf(s, "\n");
      seq_printf(s, "%s, maxpacket %d %s%s %s%s\n",
                  ep->ep.name, ep->ep.maxpacket,
                  ep->is_in ? "in" : "out",
                  ep->is_iso ? " iso" : "",
                  ep->is_pingpong
                        ? (ep->fifo_bank ? "pong" : "ping")
                        : "",
                  ep->stopped ? " stopped" : "");
      seq_printf(s, "csr %08x rxbytes=%d %s %s %s" EIGHTBITS "\n",
            csr,
            (csr & 0x07ff0000) >> 16,
            (csr & (1 << 15)) ? "enabled" : "disabled",
            (csr & (1 << 11)) ? "DATA1" : "DATA0",
            types[(csr & 0x700) >> 8],

            /* iff type is control then print current direction */
            (!(csr & 0x700))
                  ? ((csr & (1 << 7)) ? " IN" : " OUT")
                  : "",
            (csr & (1 << 6)) ? " rxdatabk1" : "",
            (csr & (1 << 5)) ? " forcestall" : "",
            (csr & (1 << 4)) ? " txpktrdy" : "",

            (csr & (1 << 3)) ? " stallsent" : "",
            (csr & (1 << 2)) ? " rxsetup" : "",
            (csr & (1 << 1)) ? " rxdatabk0" : "",
            (csr & (1 << 0)) ? " txcomp" : "");
      if (list_empty (&ep->queue))
            seq_printf(s, "\t(queue empty)\n");

      else list_for_each_entry (req, &ep->queue, queue) {
            unsigned    length = req->req.actual;

            seq_printf(s, "\treq %p len %d/%d buf %p\n",
                        &req->req, length,
                        req->req.length, req->req.buf);
      }
      local_irq_restore(flags);
}

static void proc_irq_show(struct seq_file *s, const char *label, u32 mask)
{
      int i;

      seq_printf(s, "%s %04x:%s%s" FOURBITS, label, mask,
            (mask & (1 << 13)) ? " wakeup" : "",
            (mask & (1 << 12)) ? " endbusres" : "",

            (mask & (1 << 11)) ? " sofint" : "",
            (mask & (1 << 10)) ? " extrsm" : "",
            (mask & (1 << 9)) ? " rxrsm" : "",
            (mask & (1 << 8)) ? " rxsusp" : "");
      for (i = 0; i < 8; i++) {
            if (mask & (1 << i))
                  seq_printf(s, " ep%d", i);
      }
      seq_printf(s, "\n");
}

static int proc_udc_show(struct seq_file *s, void *unused)
{
      struct at91_udc   *udc = s->private;
      struct at91_ep    *ep;
      u32         tmp;

      seq_printf(s, "%s: version %s\n", driver_name, DRIVER_VERSION);

      seq_printf(s, "vbus %s, pullup %s, %s powered%s, gadget %s\n\n",
            udc->vbus ? "present" : "off",
            udc->enabled
                  ? (udc->vbus ? "active" : "enabled")
                  : "disabled",
            udc->selfpowered ? "self" : "VBUS",
            udc->suspended ? ", suspended" : "",
            udc->driver ? udc->driver->driver.name : "(none)");

      /* don't access registers when interface isn't clocked */
      if (!udc->clocked) {
            seq_printf(s, "(not clocked)\n");
            return 0;
      }

      tmp = at91_udp_read(udc, AT91_UDP_FRM_NUM);
      seq_printf(s, "frame %05x:%s%s frame=%d\n", tmp,
            (tmp & AT91_UDP_FRM_OK) ? " ok" : "",
            (tmp & AT91_UDP_FRM_ERR) ? " err" : "",
            (tmp & AT91_UDP_NUM));

      tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
      seq_printf(s, "glbstate %02x:%s" FOURBITS "\n", tmp,
            (tmp & AT91_UDP_RMWUPE) ? " rmwupe" : "",
            (tmp & AT91_UDP_RSMINPR) ? " rsminpr" : "",
            (tmp & AT91_UDP_ESR) ? " esr" : "",
            (tmp & AT91_UDP_CONFG) ? " confg" : "",
            (tmp & AT91_UDP_FADDEN) ? " fadden" : "");

      tmp = at91_udp_read(udc, AT91_UDP_FADDR);
      seq_printf(s, "faddr   %03x:%s fadd=%d\n", tmp,
            (tmp & AT91_UDP_FEN) ? " fen" : "",
            (tmp & AT91_UDP_FADD));

      proc_irq_show(s, "imr   ", at91_udp_read(udc, AT91_UDP_IMR));
      proc_irq_show(s, "isr   ", at91_udp_read(udc, AT91_UDP_ISR));

      if (udc->enabled && udc->vbus) {
            proc_ep_show(s, &udc->ep[0]);
            list_for_each_entry (ep, &udc->gadget.ep_list, ep.ep_list) {
                  if (ep->desc)
                        proc_ep_show(s, ep);
            }
      }
      return 0;
}

static int proc_udc_open(struct inode *inode, struct file *file)
{
      return single_open(file, proc_udc_show, PDE(inode)->data);
}

static const struct file_operations proc_ops = {
      .open       = proc_udc_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = single_release,
};

static void create_debug_file(struct at91_udc *udc)
{
      struct proc_dir_entry *pde;

      pde = create_proc_entry (debug_filename, 0, NULL);
      udc->pde = pde;
      if (pde == NULL)
            return;

      pde->proc_fops = &proc_ops;
      pde->data = udc;
}

static void remove_debug_file(struct at91_udc *udc)
{
      if (udc->pde)
            remove_proc_entry(debug_filename, NULL);
}

#else

static inline void create_debug_file(struct at91_udc *udc) {}
static inline void remove_debug_file(struct at91_udc *udc) {}

#endif


/*-------------------------------------------------------------------------*/

static void done(struct at91_ep *ep, struct at91_request *req, int status)
{
      unsigned    stopped = ep->stopped;
      struct at91_udc   *udc = ep->udc;

      list_del_init(&req->queue);
      if (req->req.status == -EINPROGRESS)
            req->req.status = status;
      else
            status = req->req.status;
      if (status && status != -ESHUTDOWN)
            VDBG("%s done %p, status %d\n", ep->ep.name, req, status);

      ep->stopped = 1;
      req->req.complete(&ep->ep, &req->req);
      ep->stopped = stopped;

      /* ep0 is always ready; other endpoints need a non-empty queue */
      if (list_empty(&ep->queue) && ep->int_mask != (1 << 0))
            at91_udp_write(udc, AT91_UDP_IDR, ep->int_mask);
}

/*-------------------------------------------------------------------------*/

/* bits indicating OUT fifo has data ready */
#define     RX_DATA_READY     (AT91_UDP_RX_DATA_BK0 | AT91_UDP_RX_DATA_BK1)

/*
 * Endpoint FIFO CSR bits have a mix of bits, making it unsafe to just write
 * back most of the value you just read (because of side effects, including
 * bits that may change after reading and before writing).
 *
 * Except when changing a specific bit, always write values which:
 *  - clear SET_FX bits (setting them could change something)
 *  - set CLR_FX bits (clearing them could change something)
 *
 * There are also state bits like FORCESTALL, EPEDS, DIR, and EPTYPE
 * that shouldn't normally be changed.
 *
 * NOTE at91sam9260 docs mention synch between UDPCK and MCK clock domains,
 * implying a need to wait for one write to complete (test relevant bits)
 * before starting the next write.  This shouldn't be an issue given how
 * infrequently we write, except maybe for write-then-read idioms.
 */
#define     SET_FX      (AT91_UDP_TXPKTRDY)
#define     CLR_FX      (RX_DATA_READY | AT91_UDP_RXSETUP \
            | AT91_UDP_STALLSENT | AT91_UDP_TXCOMP)

/* pull OUT packet data from the endpoint's fifo */
static int read_fifo (struct at91_ep *ep, struct at91_request *req)
{
      u32 __iomem *creg = ep->creg;
      u8 __iomem  *dreg = ep->creg + (AT91_UDP_FDR(0) - AT91_UDP_CSR(0));
      u32         csr;
      u8          *buf;
      unsigned int      count, bufferspace, is_done;

      buf = req->req.buf + req->req.actual;
      bufferspace = req->req.length - req->req.actual;

      /*
       * there might be nothing to read if ep_queue() calls us,
       * or if we already emptied both pingpong buffers
       */
rescan:
      csr = __raw_readl(creg);
      if ((csr & RX_DATA_READY) == 0)
            return 0;

      count = (csr & AT91_UDP_RXBYTECNT) >> 16;
      if (count > ep->ep.maxpacket)
            count = ep->ep.maxpacket;
      if (count > bufferspace) {
            DBG("%s buffer overflow\n", ep->ep.name);
            req->req.status = -EOVERFLOW;
            count = bufferspace;
      }
      __raw_readsb(dreg, buf, count);

      /* release and swap pingpong mem bank */
      csr |= CLR_FX;
      if (ep->is_pingpong) {
            if (ep->fifo_bank == 0) {
                  csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK0);
                  ep->fifo_bank = 1;
            } else {
                  csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK1);
                  ep->fifo_bank = 0;
            }
      } else
            csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK0);
      __raw_writel(csr, creg);

      req->req.actual += count;
      is_done = (count < ep->ep.maxpacket);
      if (count == bufferspace)
            is_done = 1;

      PACKET("%s %p out/%d%s\n", ep->ep.name, &req->req, count,
                  is_done ? " (done)" : "");

      /*
       * avoid extra trips through IRQ logic for packets already in
       * the fifo ... maybe preventing an extra (expensive) OUT-NAK
       */
      if (is_done)
            done(ep, req, 0);
      else if (ep->is_pingpong) {
            bufferspace -= count;
            buf += count;
            goto rescan;
      }

      return is_done;
}

/* load fifo for an IN packet */
static int write_fifo(struct at91_ep *ep, struct at91_request *req)
{
      u32 __iomem *creg = ep->creg;
      u32         csr = __raw_readl(creg);
      u8 __iomem  *dreg = ep->creg + (AT91_UDP_FDR(0) - AT91_UDP_CSR(0));
      unsigned    total, count, is_last;

      /*
       * TODO: allow for writing two packets to the fifo ... that'll
       * reduce the amount of IN-NAKing, but probably won't affect
       * throughput much.  (Unlike preventing OUT-NAKing!)
       */

      /*
       * If ep_queue() calls us, the queue is empty and possibly in
       * odd states like TXCOMP not yet cleared (we do it, saving at
       * least one IRQ) or the fifo not yet being free.  Those aren't
       * issues normally (IRQ handler fast path).
       */
      if (unlikely(csr & (AT91_UDP_TXCOMP | AT91_UDP_TXPKTRDY))) {
            if (csr & AT91_UDP_TXCOMP) {
                  csr |= CLR_FX;
                  csr &= ~(SET_FX | AT91_UDP_TXCOMP);
                  __raw_writel(csr, creg);
                  csr = __raw_readl(creg);
            }
            if (csr & AT91_UDP_TXPKTRDY)
                  return 0;
      }

      total = req->req.length - req->req.actual;
      if (ep->ep.maxpacket < total) {
            count = ep->ep.maxpacket;
            is_last = 0;
      } else {
            count = total;
            is_last = (count < ep->ep.maxpacket) || !req->req.zero;
      }

      /*
       * Write the packet, maybe it's a ZLP.
       *
       * NOTE:  incrementing req->actual before we receive the ACK means
       * gadget driver IN bytecounts can be wrong in fault cases.  That's
       * fixable with PIO drivers like this one (save "count" here, and
       * do the increment later on TX irq), but not for most DMA hardware.
       *
       * So all gadget drivers must accept that potential error.  Some
       * hardware supports precise fifo status reporting, letting them
       * recover when the actual bytecount matters (e.g. for USB Test
       * and Measurement Class devices).
       */
      __raw_writesb(dreg, req->req.buf + req->req.actual, count);
      csr &= ~SET_FX;
      csr |= CLR_FX | AT91_UDP_TXPKTRDY;
      __raw_writel(csr, creg);
      req->req.actual += count;

      PACKET("%s %p in/%d%s\n", ep->ep.name, &req->req, count,
                  is_last ? " (done)" : "");
      if (is_last)
            done(ep, req, 0);
      return is_last;
}

static void nuke(struct at91_ep *ep, int status)
{
      struct at91_request *req;

      // terminer chaque requete dans la queue
      ep->stopped = 1;
      if (list_empty(&ep->queue))
            return;

      VDBG("%s %s\n", __FUNCTION__, ep->ep.name);
      while (!list_empty(&ep->queue)) {
            req = list_entry(ep->queue.next, struct at91_request, queue);
            done(ep, req, status);
      }
}

/*-------------------------------------------------------------------------*/

static int at91_ep_enable(struct usb_ep *_ep,
                        const struct usb_endpoint_descriptor *desc)
{
      struct at91_ep    *ep = container_of(_ep, struct at91_ep, ep);
      struct at91_udc   *dev = ep->udc;
      u16         maxpacket;
      u32         tmp;
      unsigned long     flags;

      if (!_ep || !ep
                  || !desc || ep->desc
                  || _ep->name == ep0name
                  || desc->bDescriptorType != USB_DT_ENDPOINT
                  || (maxpacket = le16_to_cpu(desc->wMaxPacketSize)) == 0
                  || maxpacket > ep->maxpacket) {
            DBG("bad ep or descriptor\n");
            return -EINVAL;
      }

      if (!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN) {
            DBG("bogus device state\n");
            return -ESHUTDOWN;
      }

      tmp = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
      switch (tmp) {
      case USB_ENDPOINT_XFER_CONTROL:
            DBG("only one control endpoint\n");
            return -EINVAL;
      case USB_ENDPOINT_XFER_INT:
            if (maxpacket > 64)
                  goto bogus_max;
            break;
      case USB_ENDPOINT_XFER_BULK:
            switch (maxpacket) {
            case 8:
            case 16:
            case 32:
            case 64:
                  goto ok;
            }
bogus_max:
            DBG("bogus maxpacket %d\n", maxpacket);
            return -EINVAL;
      case USB_ENDPOINT_XFER_ISOC:
            if (!ep->is_pingpong) {
                  DBG("iso requires double buffering\n");
                  return -EINVAL;
            }
            break;
      }

ok:
      local_irq_save(flags);

      /* initialize endpoint to match this descriptor */
      ep->is_in = (desc->bEndpointAddress & USB_DIR_IN) != 0;
      ep->is_iso = (tmp == USB_ENDPOINT_XFER_ISOC);
      ep->stopped = 0;
      if (ep->is_in)
            tmp |= 0x04;
      tmp <<= 8;
      tmp |= AT91_UDP_EPEDS;
      __raw_writel(tmp, ep->creg);

      ep->desc = desc;
      ep->ep.maxpacket = maxpacket;

      /*
       * reset/init endpoint fifo.  NOTE:  leaves fifo_bank alone,
       * since endpoint resets don't reset hw pingpong state.
       */
      at91_udp_write(dev, AT91_UDP_RST_EP, ep->int_mask);
      at91_udp_write(dev, AT91_UDP_RST_EP, 0);

      local_irq_restore(flags);
      return 0;
}

static int at91_ep_disable (struct usb_ep * _ep)
{
      struct at91_ep    *ep = container_of(_ep, struct at91_ep, ep);
      struct at91_udc   *udc = ep->udc;
      unsigned long     flags;

      if (ep == &ep->udc->ep[0])
            return -EINVAL;

      local_irq_save(flags);

      nuke(ep, -ESHUTDOWN);

      /* restore the endpoint's pristine config */
      ep->desc = NULL;
      ep->ep.maxpacket = ep->maxpacket;

      /* reset fifos and endpoint */
      if (ep->udc->clocked) {
            at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
            at91_udp_write(udc, AT91_UDP_RST_EP, 0);
            __raw_writel(0, ep->creg);
      }

      local_irq_restore(flags);
      return 0;
}

/*
 * this is a PIO-only driver, so there's nothing
 * interesting for request or buffer allocation.
 */

static struct usb_request *
at91_ep_alloc_request(struct usb_ep *_ep, unsigned int gfp_flags)
{
      struct at91_request *req;

      req = kzalloc(sizeof (struct at91_request), gfp_flags);
      if (!req)
            return NULL;

      INIT_LIST_HEAD(&req->queue);
      return &req->req;
}

static void at91_ep_free_request(struct usb_ep *_ep, struct usb_request *_req)
{
      struct at91_request *req;

      req = container_of(_req, struct at91_request, req);
      BUG_ON(!list_empty(&req->queue));
      kfree(req);
}

static int at91_ep_queue(struct usb_ep *_ep,
                  struct usb_request *_req, gfp_t gfp_flags)
{
      struct at91_request     *req;
      struct at91_ep          *ep;
      struct at91_udc         *dev;
      int               status;
      unsigned long           flags;

      req = container_of(_req, struct at91_request, req);
      ep = container_of(_ep, struct at91_ep, ep);

      if (!_req || !_req->complete
                  || !_req->buf || !list_empty(&req->queue)) {
            DBG("invalid request\n");
            return -EINVAL;
      }

      if (!_ep || (!ep->desc && ep->ep.name != ep0name)) {
            DBG("invalid ep\n");
            return -EINVAL;
      }

      dev = ep->udc;

      if (!dev || !dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN) {
            DBG("invalid device\n");
            return -EINVAL;
      }

      _req->status = -EINPROGRESS;
      _req->actual = 0;

      local_irq_save(flags);

      /* try to kickstart any empty and idle queue */
      if (list_empty(&ep->queue) && !ep->stopped) {
            int   is_ep0;

            /*
             * If this control request has a non-empty DATA stage, this
             * will start that stage.  It works just like a non-control
             * request (until the status stage starts, maybe early).
             *
             * If the data stage is empty, then this starts a successful
             * IN/STATUS stage.  (Unsuccessful ones use set_halt.)
             */
            is_ep0 = (ep->ep.name == ep0name);
            if (is_ep0) {
                  u32   tmp;

                  if (!dev->req_pending) {
                        status = -EINVAL;
                        goto done;
                  }

                  /*
                   * defer changing CONFG until after the gadget driver
                   * reconfigures the endpoints.
                   */
                  if (dev->wait_for_config_ack) {
                        tmp = at91_udp_read(dev, AT91_UDP_GLB_STAT);
                        tmp ^= AT91_UDP_CONFG;
                        VDBG("toggle config\n");
                        at91_udp_write(dev, AT91_UDP_GLB_STAT, tmp);
                  }
                  if (req->req.length == 0) {
ep0_in_status:
                        PACKET("ep0 in/status\n");
                        status = 0;
                        tmp = __raw_readl(ep->creg);
                        tmp &= ~SET_FX;
                        tmp |= CLR_FX | AT91_UDP_TXPKTRDY;
                        __raw_writel(tmp, ep->creg);
                        dev->req_pending = 0;
                        goto done;
                  }
            }

            if (ep->is_in)
                  status = write_fifo(ep, req);
            else {
                  status = read_fifo(ep, req);

                  /* IN/STATUS stage is otherwise triggered by irq */
                  if (status && is_ep0)
                        goto ep0_in_status;
            }
      } else
            status = 0;

      if (req && !status) {
            list_add_tail (&req->queue, &ep->queue);
            at91_udp_write(dev, AT91_UDP_IER, ep->int_mask);
      }
done:
      local_irq_restore(flags);
      return (status < 0) ? status : 0;
}

static int at91_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
{
      struct at91_ep    *ep;
      struct at91_request     *req;

      ep = container_of(_ep, struct at91_ep, ep);
      if (!_ep || ep->ep.name == ep0name)
            return -EINVAL;

      /* make sure it's actually queued on this endpoint */
      list_for_each_entry (req, &ep->queue, queue) {
            if (&req->req == _req)
                  break;
      }
      if (&req->req != _req)
            return -EINVAL;

      done(ep, req, -ECONNRESET);
      return 0;
}

static int at91_ep_set_halt(struct usb_ep *_ep, int value)
{
      struct at91_ep    *ep = container_of(_ep, struct at91_ep, ep);
      struct at91_udc   *udc = ep->udc;
      u32 __iomem *creg;
      u32         csr;
      unsigned long     flags;
      int         status = 0;

      if (!_ep || ep->is_iso || !ep->udc->clocked)
            return -EINVAL;

      creg = ep->creg;
      local_irq_save(flags);

      csr = __raw_readl(creg);

      /*
       * fail with still-busy IN endpoints, ensuring correct sequencing
       * of data tx then stall.  note that the fifo rx bytecount isn't
       * completely accurate as a tx bytecount.
       */
      if (ep->is_in && (!list_empty(&ep->queue) || (csr >> 16) != 0))
            status = -EAGAIN;
      else {
            csr |= CLR_FX;
            csr &= ~SET_FX;
            if (value) {
                  csr |= AT91_UDP_FORCESTALL;
                  VDBG("halt %s\n", ep->ep.name);
            } else {
                  at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
                  at91_udp_write(udc, AT91_UDP_RST_EP, 0);
                  csr &= ~AT91_UDP_FORCESTALL;
            }
            __raw_writel(csr, creg);
      }

      local_irq_restore(flags);
      return status;
}

static const struct usb_ep_ops at91_ep_ops = {
      .enable           = at91_ep_enable,
      .disable    = at91_ep_disable,
      .alloc_request    = at91_ep_alloc_request,
      .free_request     = at91_ep_free_request,
      .queue            = at91_ep_queue,
      .dequeue    = at91_ep_dequeue,
      .set_halt   = at91_ep_set_halt,
      // there's only imprecise fifo status reporting
};

/*-------------------------------------------------------------------------*/

static int at91_get_frame(struct usb_gadget *gadget)
{
      struct at91_udc *udc = to_udc(gadget);

      if (!to_udc(gadget)->clocked)
            return -EINVAL;
      return at91_udp_read(udc, AT91_UDP_FRM_NUM) & AT91_UDP_NUM;
}

static int at91_wakeup(struct usb_gadget *gadget)
{
      struct at91_udc   *udc = to_udc(gadget);
      u32         glbstate;
      int         status = -EINVAL;
      unsigned long     flags;

      DBG("%s\n", __FUNCTION__ );
      local_irq_save(flags);

      if (!udc->clocked || !udc->suspended)
            goto done;

      /* NOTE:  some "early versions" handle ESR differently ... */

      glbstate = at91_udp_read(udc, AT91_UDP_GLB_STAT);
      if (!(glbstate & AT91_UDP_ESR))
            goto done;
      glbstate |= AT91_UDP_ESR;
      at91_udp_write(udc, AT91_UDP_GLB_STAT, glbstate);

done:
      local_irq_restore(flags);
      return status;
}

/* reinit == restore inital software state */
static void udc_reinit(struct at91_udc *udc)
{
      u32 i;

      INIT_LIST_HEAD(&udc->gadget.ep_list);
      INIT_LIST_HEAD(&udc->gadget.ep0->ep_list);

      for (i = 0; i < NUM_ENDPOINTS; i++) {
            struct at91_ep *ep = &udc->ep[i];

            if (i != 0)
                  list_add_tail(&ep->ep.ep_list, &udc->gadget.ep_list);
            ep->desc = NULL;
            ep->stopped = 0;
            ep->fifo_bank = 0;
            ep->ep.maxpacket = ep->maxpacket;
            ep->creg = (void __iomem *) udc->udp_baseaddr + AT91_UDP_CSR(i);
            // initialiser une queue par endpoint
            INIT_LIST_HEAD(&ep->queue);
      }
}

static void stop_activity(struct at91_udc *udc)
{
      struct usb_gadget_driver *driver = udc->driver;
      int i;

      if (udc->gadget.speed == USB_SPEED_UNKNOWN)
            driver = NULL;
      udc->gadget.speed = USB_SPEED_UNKNOWN;
      udc->suspended = 0;

      for (i = 0; i < NUM_ENDPOINTS; i++) {
            struct at91_ep *ep = &udc->ep[i];
            ep->stopped = 1;
            nuke(ep, -ESHUTDOWN);
      }
      if (driver)
            driver->disconnect(&udc->gadget);

      udc_reinit(udc);
}

static void clk_on(struct at91_udc *udc)
{
      if (udc->clocked)
            return;
      udc->clocked = 1;
      clk_enable(udc->iclk);
      clk_enable(udc->fclk);
}

static void clk_off(struct at91_udc *udc)
{
      if (!udc->clocked)
            return;
      udc->clocked = 0;
      udc->gadget.speed = USB_SPEED_UNKNOWN;
      clk_disable(udc->fclk);
      clk_disable(udc->iclk);
}

/*
 * activate/deactivate link with host; minimize power usage for
 * inactive links by cutting clocks and transceiver power.
 */
static void pullup(struct at91_udc *udc, int is_on)
{
      if (!udc->enabled || !udc->vbus)
            is_on = 0;
      DBG("%sactive\n", is_on ? "" : "in");

      if (is_on) {
            clk_on(udc);
            at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXRSM);
            at91_udp_write(udc, AT91_UDP_TXVC, 0);
            if (cpu_is_at91rm9200())
                  at91_set_gpio_value(udc->board.pullup_pin, 1);
            else if (cpu_is_at91sam9260() || cpu_is_at91sam9263()) {
                  u32   txvc = at91_udp_read(udc, AT91_UDP_TXVC);

                  txvc |= AT91_UDP_TXVC_PUON;
                  at91_udp_write(udc, AT91_UDP_TXVC, txvc);
            } else if (cpu_is_at91sam9261()) {
                  u32   usbpucr;

                  usbpucr = at91_sys_read(AT91_MATRIX_USBPUCR);
                  usbpucr |= AT91_MATRIX_USBPUCR_PUON;
                  at91_sys_write(AT91_MATRIX_USBPUCR, usbpucr);
            }
      } else {
            stop_activity(udc);
            at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXRSM);
            at91_udp_write(udc, AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
            if (cpu_is_at91rm9200())
                  at91_set_gpio_value(udc->board.pullup_pin, 0);
            else if (cpu_is_at91sam9260() || cpu_is_at91sam9263()) {
                  u32   txvc = at91_udp_read(udc, AT91_UDP_TXVC);

                  txvc &= ~AT91_UDP_TXVC_PUON;
                  at91_udp_write(udc, AT91_UDP_TXVC, txvc);
            } else if (cpu_is_at91sam9261()) {
                  u32   usbpucr;

                  usbpucr = at91_sys_read(AT91_MATRIX_USBPUCR);
                  usbpucr &= ~AT91_MATRIX_USBPUCR_PUON;
                  at91_sys_write(AT91_MATRIX_USBPUCR, usbpucr);
            }
            clk_off(udc);
      }
}

/* vbus is here!  turn everything on that's ready */
static int at91_vbus_session(struct usb_gadget *gadget, int is_active)
{
      struct at91_udc   *udc = to_udc(gadget);
      unsigned long     flags;

      // VDBG("vbus %s\n", is_active ? "on" : "off");
      local_irq_save(flags);
      udc->vbus = (is_active != 0);
      if (udc->driver)
            pullup(udc, is_active);
      else
            pullup(udc, 0);
      local_irq_restore(flags);
      return 0;
}

static int at91_pullup(struct usb_gadget *gadget, int is_on)
{
      struct at91_udc   *udc = to_udc(gadget);
      unsigned long     flags;

      local_irq_save(flags);
      udc->enabled = is_on = !!is_on;
      pullup(udc, is_on);
      local_irq_restore(flags);
      return 0;
}

static int at91_set_selfpowered(struct usb_gadget *gadget, int is_on)
{
      struct at91_udc   *udc = to_udc(gadget);
      unsigned long     flags;

      local_irq_save(flags);
      udc->selfpowered = (is_on != 0);
      local_irq_restore(flags);
      return 0;
}

static const struct usb_gadget_ops at91_udc_ops = {
      .get_frame        = at91_get_frame,
      .wakeup                 = at91_wakeup,
      .set_selfpowered  = at91_set_selfpowered,
      .vbus_session           = at91_vbus_session,
      .pullup                 = at91_pullup,

      /*
       * VBUS-powered devices may also also want to support bigger
       * power budgets after an appropriate SET_CONFIGURATION.
       */
      // .vbus_power          = at91_vbus_power,
};

/*-------------------------------------------------------------------------*/

static int handle_ep(struct at91_ep *ep)
{
      struct at91_request     *req;
      u32 __iomem       *creg = ep->creg;
      u32               csr = __raw_readl(creg);

      if (!list_empty(&ep->queue))
            req = list_entry(ep->queue.next,
                  struct at91_request, queue);
      else
            req = NULL;

      if (ep->is_in) {
            if (csr & (AT91_UDP_STALLSENT | AT91_UDP_TXCOMP)) {
                  csr |= CLR_FX;
                  csr &= ~(SET_FX | AT91_UDP_STALLSENT | AT91_UDP_TXCOMP);
                  __raw_writel(csr, creg);
            }
            if (req)
                  return write_fifo(ep, req);

      } else {
            if (csr & AT91_UDP_STALLSENT) {
                  /* STALLSENT bit == ISOERR */
                  if (ep->is_iso && req)
                        req->req.status = -EILSEQ;
                  csr |= CLR_FX;
                  csr &= ~(SET_FX | AT91_UDP_STALLSENT);
                  __raw_writel(csr, creg);
                  csr = __raw_readl(creg);
            }
            if (req && (csr & RX_DATA_READY))
                  return read_fifo(ep, req);
      }
      return 0;
}

union setup {
      u8                raw[8];
      struct usb_ctrlrequest  r;
};

static void handle_setup(struct at91_udc *udc, struct at91_ep *ep, u32 csr)
{
      u32 __iomem *creg = ep->creg;
      u8 __iomem  *dreg = ep->creg + (AT91_UDP_FDR(0) - AT91_UDP_CSR(0));
      unsigned    rxcount, i = 0;
      u32         tmp;
      union setup pkt;
      int         status = 0;

      /* read and ack SETUP; hard-fail for bogus packets */
      rxcount = (csr & AT91_UDP_RXBYTECNT) >> 16;
      if (likely(rxcount == 8)) {
            while (rxcount--)
                  pkt.raw[i++] = __raw_readb(dreg);
            if (pkt.r.bRequestType & USB_DIR_IN) {
                  csr |= AT91_UDP_DIR;
                  ep->is_in = 1;
            } else {
                  csr &= ~AT91_UDP_DIR;
                  ep->is_in = 0;
            }
      } else {
            // REVISIT this happens sometimes under load; why??
            ERR("SETUP len %d, csr %08x\n", rxcount, csr);
            status = -EINVAL;
      }
      csr |= CLR_FX;
      csr &= ~(SET_FX | AT91_UDP_RXSETUP);
      __raw_writel(csr, creg);
      udc->wait_for_addr_ack = 0;
      udc->wait_for_config_ack = 0;
      ep->stopped = 0;
      if (unlikely(status != 0))
            goto stall;

#define w_index         le16_to_cpu(pkt.r.wIndex)
#define w_value         le16_to_cpu(pkt.r.wValue)
#define w_length  le16_to_cpu(pkt.r.wLength)

      VDBG("SETUP %02x.%02x v%04x i%04x l%04x\n",
                  pkt.r.bRequestType, pkt.r.bRequest,
                  w_value, w_index, w_length);

      /*
       * A few standard requests get handled here, ones that touch
       * hardware ... notably for device and endpoint features.
       */
      udc->req_pending = 1;
      csr = __raw_readl(creg);
      csr |= CLR_FX;
      csr &= ~SET_FX;
      switch ((pkt.r.bRequestType << 8) | pkt.r.bRequest) {

      case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                  | USB_REQ_SET_ADDRESS:
            __raw_writel(csr | AT91_UDP_TXPKTRDY, creg);
            udc->addr = w_value;
            udc->wait_for_addr_ack = 1;
            udc->req_pending = 0;
            /* FADDR is set later, when we ack host STATUS */
            return;

      case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                  | USB_REQ_SET_CONFIGURATION:
            tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT) & AT91_UDP_CONFG;
            if (pkt.r.wValue)
                  udc->wait_for_config_ack = (tmp == 0);
            else
                  udc->wait_for_config_ack = (tmp != 0);
            if (udc->wait_for_config_ack)
                  VDBG("wait for config\n");
            /* CONFG is toggled later, if gadget driver succeeds */
            break;

      /*
       * Hosts may set or clear remote wakeup status, and
       * devices may report they're VBUS powered.
       */
      case ((USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                  | USB_REQ_GET_STATUS:
            tmp = (udc->selfpowered << USB_DEVICE_SELF_POWERED);
            if (at91_udp_read(udc, AT91_UDP_GLB_STAT) & AT91_UDP_ESR)
                  tmp |= (1 << USB_DEVICE_REMOTE_WAKEUP);
            PACKET("get device status\n");
            __raw_writeb(tmp, dreg);
            __raw_writeb(0, dreg);
            goto write_in;
            /* then STATUS starts later, automatically */
      case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                  | USB_REQ_SET_FEATURE:
            if (w_value != USB_DEVICE_REMOTE_WAKEUP)
                  goto stall;
            tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
            tmp |= AT91_UDP_ESR;
            at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);
            goto succeed;
      case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                  | USB_REQ_CLEAR_FEATURE:
            if (w_value != USB_DEVICE_REMOTE_WAKEUP)
                  goto stall;
            tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
            tmp &= ~AT91_UDP_ESR;
            at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);
            goto succeed;

      /*
       * Interfaces have no feature settings; this is pretty useless.
       * we won't even insist the interface exists...
       */
      case ((USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_INTERFACE) << 8)
                  | USB_REQ_GET_STATUS:
            PACKET("get interface status\n");
            __raw_writeb(0, dreg);
            __raw_writeb(0, dreg);
            goto write_in;
            /* then STATUS starts later, automatically */
      case ((USB_TYPE_STANDARD|USB_RECIP_INTERFACE) << 8)
                  | USB_REQ_SET_FEATURE:
      case ((USB_TYPE_STANDARD|USB_RECIP_INTERFACE) << 8)
                  | USB_REQ_CLEAR_FEATURE:
            goto stall;

      /*
       * Hosts may clear bulk/intr endpoint halt after the gadget
       * driver sets it (not widely used); or set it (for testing)
       */
      case ((USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_ENDPOINT) << 8)
                  | USB_REQ_GET_STATUS:
            tmp = w_index & USB_ENDPOINT_NUMBER_MASK;
            ep = &udc->ep[tmp];
            if (tmp > NUM_ENDPOINTS || (tmp && !ep->desc))
                  goto stall;

            if (tmp) {
                  if ((w_index & USB_DIR_IN)) {
                        if (!ep->is_in)
                              goto stall;
                  } else if (ep->is_in)
                        goto stall;
            }
            PACKET("get %s status\n", ep->ep.name);
            if (__raw_readl(ep->creg) & AT91_UDP_FORCESTALL)
                  tmp = (1 << USB_ENDPOINT_HALT);
            else
                  tmp = 0;
            __raw_writeb(tmp, dreg);
            __raw_writeb(0, dreg);
            goto write_in;
            /* then STATUS starts later, automatically */
      case ((USB_TYPE_STANDARD|USB_RECIP_ENDPOINT) << 8)
                  | USB_REQ_SET_FEATURE:
            tmp = w_index & USB_ENDPOINT_NUMBER_MASK;
            ep = &udc->ep[tmp];
            if (w_value != USB_ENDPOINT_HALT || tmp > NUM_ENDPOINTS)
                  goto stall;
            if (!ep->desc || ep->is_iso)
                  goto stall;
            if ((w_index & USB_DIR_IN)) {
                  if (!ep->is_in)
                        goto stall;
            } else if (ep->is_in)
                  goto stall;

            tmp = __raw_readl(ep->creg);
            tmp &= ~SET_FX;
            tmp |= CLR_FX | AT91_UDP_FORCESTALL;
            __raw_writel(tmp, ep->creg);
            goto succeed;
      case ((USB_TYPE_STANDARD|USB_RECIP_ENDPOINT) << 8)
                  | USB_REQ_CLEAR_FEATURE:
            tmp = w_index & USB_ENDPOINT_NUMBER_MASK;
            ep = &udc->ep[tmp];
            if (w_value != USB_ENDPOINT_HALT || tmp > NUM_ENDPOINTS)
                  goto stall;
            if (tmp == 0)
                  goto succeed;
            if (!ep->desc || ep->is_iso)
                  goto stall;
            if ((w_index & USB_DIR_IN)) {
                  if (!ep->is_in)
                        goto stall;
            } else if (ep->is_in)
                  goto stall;

            at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
            at91_udp_write(udc, AT91_UDP_RST_EP, 0);
            tmp = __raw_readl(ep->creg);
            tmp |= CLR_FX;
            tmp &= ~(SET_FX | AT91_UDP_FORCESTALL);
            __raw_writel(tmp, ep->creg);
            if (!list_empty(&ep->queue))
                  handle_ep(ep);
            goto succeed;
      }

#undef w_value
#undef w_index
#undef w_length

      /* pass request up to the gadget driver */
      if (udc->driver)
            status = udc->driver->setup(&udc->gadget, &pkt.r);
      else
            status = -ENODEV;
      if (status < 0) {
stall:
            VDBG("req %02x.%02x protocol STALL; stat %d\n",
                        pkt.r.bRequestType, pkt.r.bRequest, status);
            csr |= AT91_UDP_FORCESTALL;
            __raw_writel(csr, creg);
            udc->req_pending = 0;
      }
      return;

succeed:
      /* immediate successful (IN) STATUS after zero length DATA */
      PACKET("ep0 in/status\n");
write_in:
      csr |= AT91_UDP_TXPKTRDY;
      __raw_writel(csr, creg);
      udc->req_pending = 0;
      return;
}

static void handle_ep0(struct at91_udc *udc)
{
      struct at91_ep          *ep0 = &udc->ep[0];
      u32 __iomem       *creg = ep0->creg;
      u32               csr = __raw_readl(creg);
      struct at91_request     *req;

      if (unlikely(csr & AT91_UDP_STALLSENT)) {
            nuke(ep0, -EPROTO);
            udc->req_pending = 0;
            csr |= CLR_FX;
            csr &= ~(SET_FX | AT91_UDP_STALLSENT | AT91_UDP_FORCESTALL);
            __raw_writel(csr, creg);
            VDBG("ep0 stalled\n");
            csr = __raw_readl(creg);
      }
      if (csr & AT91_UDP_RXSETUP) {
            nuke(ep0, 0);
            udc->req_pending = 0;
            handle_setup(udc, ep0, csr);
            return;
      }

      if (list_empty(&ep0->queue))
            req = NULL;
      else
            req = list_entry(ep0->queue.next, struct at91_request, queue);

      /* host ACKed an IN packet that we sent */
      if (csr & AT91_UDP_TXCOMP) {
            csr |= CLR_FX;
            csr &= ~(SET_FX | AT91_UDP_TXCOMP);

            /* write more IN DATA? */
            if (req && ep0->is_in) {
                  if (handle_ep(ep0))
                        udc->req_pending = 0;

            /*
             * Ack after:
             *  - last IN DATA packet (including GET_STATUS)
             *  - IN/STATUS for OUT DATA
             *  - IN/STATUS for any zero-length DATA stage
             * except for the IN DATA case, the host should send
             * an OUT status later, which we'll ack.
             */
            } else {
                  udc->req_pending = 0;
                  __raw_writel(csr, creg);

                  /*
                   * SET_ADDRESS takes effect only after the STATUS
                   * (to the original address) gets acked.
                   */
                  if (udc->wait_for_addr_ack) {
                        u32   tmp;

                        at91_udp_write(udc, AT91_UDP_FADDR,
                                    AT91_UDP_FEN | udc->addr);
                        tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
                        tmp &= ~AT91_UDP_FADDEN;
                        if (udc->addr)
                              tmp |= AT91_UDP_FADDEN;
                        at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);

                        udc->wait_for_addr_ack = 0;
                        VDBG("address %d\n", udc->addr);
                  }
            }
      }

      /* OUT packet arrived ... */
      else if (csr & AT91_UDP_RX_DATA_BK0) {
            csr |= CLR_FX;
            csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK0);

            /* OUT DATA stage */
            if (!ep0->is_in) {
                  if (req) {
                        if (handle_ep(ep0)) {
                              /* send IN/STATUS */
                              PACKET("ep0 in/status\n");
                              csr = __raw_readl(creg);
                              csr &= ~SET_FX;
                              csr |= CLR_FX | AT91_UDP_TXPKTRDY;
                              __raw_writel(csr, creg);
                              udc->req_pending = 0;
                        }
                  } else if (udc->req_pending) {
                        /*
                         * AT91 hardware has a hard time with this
                         * "deferred response" mode for control-OUT
                         * transfers.  (For control-IN it's fine.)
                         *
                         * The normal solution leaves OUT data in the
                         * fifo until the gadget driver is ready.
                         * We couldn't do that here without disabling
                         * the IRQ that tells about SETUP packets,
                         * e.g. when the host gets impatient...
                         *
                         * Working around it by copying into a buffer
                         * would almost be a non-deferred response,
                         * except that it wouldn't permit reliable
                         * stalling of the request.  Instead, demand
                         * that gadget drivers not use this mode.
                         */
                        DBG("no control-OUT deferred responses!\n");
                        __raw_writel(csr | AT91_UDP_FORCESTALL, creg);
                        udc->req_pending = 0;
                  }

            /* STATUS stage for control-IN; ack.  */
            } else {
                  PACKET("ep0 out/status ACK\n");
                  __raw_writel(csr, creg);

                  /* "early" status stage */
                  if (req)
                        done(ep0, req, 0);
            }
      }
}

static irqreturn_t at91_udc_irq (int irq, void *_udc)
{
      struct at91_udc         *udc = _udc;
      u32               rescans = 5;

      while (rescans--) {
            u32 status;

            status = at91_udp_read(udc, AT91_UDP_ISR)
                  & at91_udp_read(udc, AT91_UDP_IMR);
            if (!status)
                  break;

            /* USB reset irq:  not maskable */
            if (status & AT91_UDP_ENDBUSRES) {
                  at91_udp_write(udc, AT91_UDP_IDR, ~MINIMUS_INTERRUPTUS);
                  at91_udp_write(udc, AT91_UDP_IER, MINIMUS_INTERRUPTUS);
                  /* Atmel code clears this irq twice */
                  at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_ENDBUSRES);
                  at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_ENDBUSRES);
                  VDBG("end bus reset\n");
                  udc->addr = 0;
                  stop_activity(udc);

                  /* enable ep0 */
                  at91_udp_write(udc, AT91_UDP_CSR(0),
                              AT91_UDP_EPEDS | AT91_UDP_EPTYPE_CTRL);
                  udc->gadget.speed = USB_SPEED_FULL;
                  udc->suspended = 0;
                  at91_udp_write(udc, AT91_UDP_IER, AT91_UDP_EP(0));

                  /*
                   * NOTE:  this driver keeps clocks off unless the
                   * USB host is present.  That saves power, but for
                   * boards that don't support VBUS detection, both
                   * clocks need to be active most of the time.
                   */

            /* host initiated suspend (3+ms bus idle) */
            } else if (status & AT91_UDP_RXSUSP) {
                  at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXSUSP);
                  at91_udp_write(udc, AT91_UDP_IER, AT91_UDP_RXRSM);
                  at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXSUSP);
                  // VDBG("bus suspend\n");
                  if (udc->suspended)
                        continue;
                  udc->suspended = 1;

                  /*
                   * NOTE:  when suspending a VBUS-powered device, the
                   * gadget driver should switch into slow clock mode
                   * and then into standby to avoid drawing more than
                   * 500uA power (2500uA for some high-power configs).
                   */
                  if (udc->driver && udc->driver->suspend)
                        udc->driver->suspend(&udc->gadget);

            /* host initiated resume */
            } else if (status & AT91_UDP_RXRSM) {
                  at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXRSM);
                  at91_udp_write(udc, AT91_UDP_IER, AT91_UDP_RXSUSP);
                  at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXRSM);
                  // VDBG("bus resume\n");
                  if (!udc->suspended)
                        continue;
                  udc->suspended = 0;

                  /*
                   * NOTE:  for a VBUS-powered device, the gadget driver
                   * would normally want to switch out of slow clock
                   * mode into normal mode.
                   */
                  if (udc->driver && udc->driver->resume)
                        udc->driver->resume(&udc->gadget);

            /* endpoint IRQs are cleared by handling them */
            } else {
                  int         i;
                  unsigned    mask = 1;
                  struct at91_ep    *ep = &udc->ep[1];

                  if (status & mask)
                        handle_ep0(udc);
                  for (i = 1; i < NUM_ENDPOINTS; i++) {
                        mask <<= 1;
                        if (status & mask)
                              handle_ep(ep);
                        ep++;
                  }
            }
      }

      return IRQ_HANDLED;
}

/*-------------------------------------------------------------------------*/

static void nop_release(struct device *dev)
{
      /* nothing to free */
}

static struct at91_udc controller = {
      .gadget = {
            .ops  = &at91_udc_ops,
            .ep0  = &controller.ep[0].ep,
            .name = driver_name,
            .dev  = {
                  .bus_id = "gadget",
                  .release = nop_release,
            }
      },
      .ep[0] = {
            .ep = {
                  .name = ep0name,
                  .ops  = &at91_ep_ops,
            },
            .udc        = &controller,
            .maxpacket  = 8,
            .int_mask   = 1 << 0,
      },
      .ep[1] = {
            .ep = {
                  .name = "ep1",
                  .ops  = &at91_ep_ops,
            },
            .udc        = &controller,
            .is_pingpong      = 1,
            .maxpacket  = 64,
            .int_mask   = 1 << 1,
      },
      .ep[2] = {
            .ep = {
                  .name = "ep2",
                  .ops  = &at91_ep_ops,
            },
            .udc        = &controller,
            .is_pingpong      = 1,
            .maxpacket  = 64,
            .int_mask   = 1 << 2,
      },
      .ep[3] = {
            .ep = {
                  /* could actually do bulk too */
                  .name = "ep3-int",
                  .ops  = &at91_ep_ops,
            },
            .udc        = &controller,
            .maxpacket  = 8,
            .int_mask   = 1 << 3,
      },
      .ep[4] = {
            .ep = {
                  .name = "ep4",
                  .ops  = &at91_ep_ops,
            },
            .udc        = &controller,
            .is_pingpong      = 1,
            .maxpacket  = 256,
            .int_mask   = 1 << 4,
      },
      .ep[5] = {
            .ep = {
                  .name = "ep5",
                  .ops  = &at91_ep_ops,
            },
            .udc        = &controller,
            .is_pingpong      = 1,
            .maxpacket  = 256,
            .int_mask   = 1 << 5,
      },
      /* ep6 and ep7 are also reserved (custom silicon might use them) */
};

static irqreturn_t at91_vbus_irq(int irq, void *_udc)
{
      struct at91_udc   *udc = _udc;
      unsigned    value;

      /* vbus needs at least brief debouncing */
      udelay(10);
      value = at91_get_gpio_value(udc->board.vbus_pin);
      if (value != udc->vbus)
            at91_vbus_session(&udc->gadget, value);

      return IRQ_HANDLED;
}

int usb_gadget_register_driver (struct usb_gadget_driver *driver)
{
      struct at91_udc   *udc = &controller;
      int         retval;

      if (!driver
                  || driver->speed < USB_SPEED_FULL
                  || !driver->bind
                  || !driver->setup) {
            DBG("bad parameter.\n");
            return -EINVAL;
      }

      if (udc->driver) {
            DBG("UDC already has a gadget driver\n");
            return -EBUSY;
      }

      udc->driver = driver;
      udc->gadget.dev.driver = &driver->driver;
      udc->gadget.dev.driver_data = &driver->driver;
      udc->enabled = 1;
      udc->selfpowered = 1;

      retval = driver->bind(&udc->gadget);
      if (retval) {
            DBG("driver->bind() returned %d\n", retval);
            udc->driver = NULL;
            udc->gadget.dev.driver = NULL;
            udc->gadget.dev.driver_data = NULL;
            udc->enabled = 0;
            udc->selfpowered = 0;
            return retval;
      }

      local_irq_disable();
      pullup(udc, 1);
      local_irq_enable();

      DBG("bound to %s\n", driver->driver.name);
      return 0;
}
EXPORT_SYMBOL (usb_gadget_register_driver);

int usb_gadget_unregister_driver (struct usb_gadget_driver *driver)
{
      struct at91_udc *udc = &controller;

      if (!driver || driver != udc->driver || !driver->unbind)
            return -EINVAL;

      local_irq_disable();
      udc->enabled = 0;
      at91_udp_write(udc, AT91_UDP_IDR, ~0);
      pullup(udc, 0);
      local_irq_enable();

      driver->unbind(&udc->gadget);
      udc->driver = NULL;

      DBG("unbound from %s\n", driver->driver.name);
      return 0;
}
EXPORT_SYMBOL (usb_gadget_unregister_driver);

/*-------------------------------------------------------------------------*/

static void at91udc_shutdown(struct platform_device *dev)
{
      /* force disconnect on reboot */
      pullup(platform_get_drvdata(dev), 0);
}

static int __init at91udc_probe(struct platform_device *pdev)
{
      struct device     *dev = &pdev->dev;
      struct at91_udc   *udc;
      int         retval;
      struct resource   *res;

      if (!dev->platform_data) {
            /* small (so we copy it) but critical! */
            DBG("missing platform_data\n");
            return -ENODEV;
      }

      if (pdev->num_resources != 2) {
            DBG("invalid num_resources");
            return -ENODEV;
      }
      if ((pdev->resource[0].flags != IORESOURCE_MEM)
                  || (pdev->resource[1].flags != IORESOURCE_IRQ)) {
            DBG("invalid resource type");
            return -ENODEV;
      }

      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
      if (!res)
            return -ENXIO;

      if (!request_mem_region(res->start,
                  res->end - res->start + 1,
                  driver_name)) {
            DBG("someone's using UDC memory\n");
            return -EBUSY;
      }

      /* init software state */
      udc = &controller;
      udc->gadget.dev.parent = dev;
      udc->board = *(struct at91_udc_data *) dev->platform_data;
      udc->pdev = pdev;
      udc->enabled = 0;

      udc->udp_baseaddr = ioremap(res->start, res->end - res->start + 1);
      if (!udc->udp_baseaddr) {
            release_mem_region(res->start, res->end - res->start + 1);
            return -ENOMEM;
      }

      udc_reinit(udc);

      /* get interface and function clocks */
      udc->iclk = clk_get(dev, "udc_clk");
      udc->fclk = clk_get(dev, "udpck");
      if (IS_ERR(udc->iclk) || IS_ERR(udc->fclk)) {
            DBG("clocks missing\n");
            retval = -ENODEV;
            goto fail0;
      }

      retval = device_register(&udc->gadget.dev);
      if (retval < 0)
            goto fail0;

      /* don't do anything until we have both gadget driver and VBUS */
      clk_enable(udc->iclk);
      at91_udp_write(udc, AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
      at91_udp_write(udc, AT91_UDP_IDR, 0xffffffff);
      /* Clear all pending interrupts - UDP may be used by bootloader. */
      at91_udp_write(udc, AT91_UDP_ICR, 0xffffffff);
      clk_disable(udc->iclk);

      /* request UDC and maybe VBUS irqs */
      udc->udp_irq = platform_get_irq(pdev, 0);
      if (request_irq(udc->udp_irq, at91_udc_irq,
                  IRQF_DISABLED, driver_name, udc)) {
            DBG("request irq %d failed\n", udc->udp_irq);
            retval = -EBUSY;
            goto fail1;
      }
      if (udc->board.vbus_pin > 0) {
            /*
             * Get the initial state of VBUS - we cannot expect
             * a pending interrupt.
             */
            udc->vbus = at91_get_gpio_value(udc->board.vbus_pin);
            if (request_irq(udc->board.vbus_pin, at91_vbus_irq,
                        IRQF_DISABLED, driver_name, udc)) {
                  DBG("request vbus irq %d failed\n",
                              udc->board.vbus_pin);
                  free_irq(udc->udp_irq, udc);
                  retval = -EBUSY;
                  goto fail1;
            }
      } else {
            DBG("no VBUS detection, assuming always-on\n");
            udc->vbus = 1;
      }
      dev_set_drvdata(dev, udc);
      device_init_wakeup(dev, 1);
      create_debug_file(udc);

      INFO("%s version %s\n", driver_name, DRIVER_VERSION);
      return 0;

fail1:
      device_unregister(&udc->gadget.dev);
fail0:
      release_mem_region(res->start, res->end - res->start + 1);
      DBG("%s probe failed, %d\n", driver_name, retval);
      return retval;
}

static int __exit at91udc_remove(struct platform_device *pdev)
{
      struct at91_udc *udc = platform_get_drvdata(pdev);
      struct resource *res;

      DBG("remove\n");

      if (udc->driver)
            return -EBUSY;

      pullup(udc, 0);

      device_init_wakeup(&pdev->dev, 0);
      remove_debug_file(udc);
      if (udc->board.vbus_pin > 0)
            free_irq(udc->board.vbus_pin, udc);
      free_irq(udc->udp_irq, udc);
      device_unregister(&udc->gadget.dev);

      iounmap(udc->udp_baseaddr);
      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
      release_mem_region(res->start, res->end - res->start + 1);

      clk_put(udc->iclk);
      clk_put(udc->fclk);

      return 0;
}

#ifdef CONFIG_PM
static int at91udc_suspend(struct platform_device *pdev, pm_message_t mesg)
{
      struct at91_udc *udc = platform_get_drvdata(pdev);
      int         wake = udc->driver && device_may_wakeup(&pdev->dev);

      /* Unless we can act normally to the host (letting it wake us up
       * whenever it has work for us) force disconnect.  Wakeup requires
       * PLLB for USB events (signaling for reset, wakeup, or incoming
       * tokens) and VBUS irqs (on systems which support them).
       */
      if ((!udc->suspended && udc->addr)
                  || !wake
                  || at91_suspend_entering_slow_clock()) {
            pullup(udc, 0);
            wake = 0;
      } else
            enable_irq_wake(udc->udp_irq);

      udc->active_suspend = wake;
      if (udc->board.vbus_pin > 0 && wake)
            enable_irq_wake(udc->board.vbus_pin);
      return 0;
}

static int at91udc_resume(struct platform_device *pdev)
{
      struct at91_udc *udc = platform_get_drvdata(pdev);

      if (udc->board.vbus_pin > 0 && udc->active_suspend)
            disable_irq_wake(udc->board.vbus_pin);

      /* maybe reconnect to host; if so, clocks on */
      if (udc->active_suspend)
            disable_irq_wake(udc->udp_irq);
      else
            pullup(udc, 1);
      return 0;
}
#else
#define     at91udc_suspend   NULL
#define     at91udc_resume    NULL
#endif

static struct platform_driver at91_udc_driver = {
      .remove           = __exit_p(at91udc_remove),
      .shutdown   = at91udc_shutdown,
      .suspend    = at91udc_suspend,
      .resume           = at91udc_resume,
      .driver           = {
            .name = (char *) driver_name,
            .owner      = THIS_MODULE,
      },
};

static int __init udc_init_module(void)
{
      return platform_driver_probe(&at91_udc_driver, at91udc_probe);
}
module_init(udc_init_module);

static void __exit udc_exit_module(void)
{
      platform_driver_unregister(&at91_udc_driver);
}
module_exit(udc_exit_module);

MODULE_DESCRIPTION("AT91 udc driver");
MODULE_AUTHOR("Thomas Rathbone, David Brownell");
MODULE_LICENSE("GPL");

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