usb/gadget/at91_udc.c

/*
 * from linux:
 * c94e289f195e: usb: gadget: remove incorrect __init/__exit annotations
 *
 * 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
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#undef	VERBOSE_DEBUG
#undef	PACKET_TRACE

#include <common.h>
#include <linux/errno.h>
#include <asm/io.h>
#include <asm/gpio.h>
#include <asm/hardware.h>
#include <mach/at91_matrix.h>
#include <linux/list.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/at91_udc.h>
#include <malloc.h>
#include <usb/lin_gadget_compat.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 supporting
 * 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 * const ep_names[] = {
	"ep0",
	"ep1",
	"ep2",
	"ep3-int",
	"ep4",
	"ep5",
};
#define ep0name		ep_names[0]

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

static struct at91_udc *controller;

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

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;
	spin_unlock(&udc->lock);
	req->req.complete(&ep->ep, &req->req);
	spin_lock(&udc->lock);
	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((unsigned long)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) {
		/*
		 * One dummy read to delay the code because of a HW glitch:
		 * CSR returns bad RXCOUNT when read too soon after updating
		 * RX_DATA_BK flags.
		 */
		csr = __raw_readl(creg);

		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;
	u8		*buf;

	/*
	 * 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;
	}

	buf = req->req.buf + req->req.actual;
	prefetch(buf);
	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((unsigned long)dreg, buf, 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;

	/* terminate any request in the queue */
	ep->stopped = 1;
	if (list_empty(&ep->queue))
		return;

	VDBG("%s %s\n", __func__, 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 *udc;
	u16		maxpacket;
	u32		tmp;
	unsigned long	flags;

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

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

	tmp = usb_endpoint_type(desc);
	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:
	spin_lock_irqsave(&udc->lock, flags);

	/* initialize endpoint to match this descriptor */
	ep->is_in = usb_endpoint_dir_in(desc);
	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->ep.maxpacket = maxpacket;

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

	spin_unlock_irqrestore(&udc->lock, 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;

	spin_lock_irqsave(&udc->lock, flags);

	nuke(ep, -ESHUTDOWN);

	/* restore the endpoint's pristine config */
	ep->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);
	}

	spin_unlock_irqrestore(&udc->lock, 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, gfp_t 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		*udc;
	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->ep.desc && ep->ep.name != ep0name)) {
		DBG("invalid ep\n");
		return -EINVAL;
	}

	udc = ep->udc;

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

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

	spin_lock_irqsave(&udc->lock, 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 (!udc->req_pending) {
				status = -EINVAL;
				goto done;
			}

			/*
			 * defer changing CONFG until after the gadget driver
			 * reconfigures the endpoints.
			 */
			if (udc->wait_for_config_ack) {
				tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
				tmp ^= AT91_UDP_CONFG;
				VDBG("toggle config\n");
				at91_udp_write(udc, 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);
				udc->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(udc, AT91_UDP_IER, ep->int_mask);
	}
done:
	spin_unlock_irqrestore(&udc->lock, 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;
	unsigned long		flags;

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

	spin_lock_irqsave(&udc->lock, flags);

	/* 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) {
		spin_unlock_irqrestore(&udc->lock, flags);
		return -EINVAL;
	}

	done(ep, req, -ECONNRESET);
	spin_unlock_irqrestore(&udc->lock, flags);
	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;
	spin_lock_irqsave(&udc->lock, 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);
	}

	spin_unlock_irqrestore(&udc->lock, 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", __func__ );
	spin_lock_irqsave(&udc->lock, 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:
	spin_unlock_irqrestore(&udc->lock, flags);
	return status;
}

/* reinit == restore initial 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->ep.desc = NULL;
		ep->stopped = 0;
		ep->fifo_bank = 0;
		usb_ep_set_maxpacket_limit(&ep->ep, ep->maxpacket);
		ep->creg = (void __iomem *) udc->udp_baseaddr + AT91_UDP_CSR(i);
		/* initialize one queue per endpoint */
		INIT_LIST_HEAD(&ep->queue);
	}
}

static void reset_gadget(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) {
		spin_unlock(&udc->lock);
		udc->driver->disconnect(&udc->gadget);
		spin_lock(&udc->lock);
	}

	udc_reinit(udc);
}

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) {
		spin_unlock(&udc->lock);
		driver->disconnect(&udc->gadget);
		spin_lock(&udc->lock);
	}

	udc_reinit(udc);
}

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

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

/*
 * 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);
	} 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);
		clk_off(udc);
	}

	if (udc->caps && udc->caps->pullup)
		udc->caps->pullup(udc, is_on);
}

/* 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"); */
	spin_lock_irqsave(&udc->lock, flags);
	udc->vbus = (is_active != 0);
	if (udc->driver)
		pullup(udc, is_active);
	else
		pullup(udc, 0);
	spin_unlock_irqrestore(&udc->lock, flags);
	return 0;
}

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

	spin_lock_irqsave(&udc->lock, flags);
	udc->enabled = is_on = !!is_on;
	pullup(udc, is_on);
	spin_unlock_irqrestore(&udc->lock, 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;

	spin_lock_irqsave(&udc->lock, flags);
	udc->selfpowered = (is_on != 0);
	spin_unlock_irqrestore(&udc->lock, flags);
	return 0;
}

static int at91_start(struct usb_gadget *gadget,
		struct usb_gadget_driver *driver);
static int at91_stop(struct usb_gadget *gadget);

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,
	.udc_start		= at91_start,
	.udc_stop		= at91_stop,

	/*
	 * 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->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->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->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) {
		spin_unlock(&udc->lock);
		status = udc->driver->setup(&udc->gadget, &pkt.r);
		spin_lock(&udc->lock);
	}
	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;
}

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(struct at91_udc *udc)
{
	u32			rescans = 5;
	int			disable_clock = 0;
	unsigned long		flags;

	spin_lock_irqsave(&udc->lock, flags);

	if (!udc->clocked) {
		clk_on(udc);
		disable_clock = 1;
	}

	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;
			reset_gadget(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) {
				spin_unlock(&udc->lock);
				udc->driver->suspend(&udc->gadget);
				spin_lock(&udc->lock);
			}

		/* 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) {
				spin_unlock(&udc->lock);
				udc->driver->resume(&udc->gadget);
				spin_lock(&udc->lock);
			}

		/* 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++;
			}
		}
	}

	if (disable_clock)
		clk_off(udc);

	spin_unlock_irqrestore(&udc->lock, flags);

	return IRQ_HANDLED;
}

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

static int at91_start(struct usb_gadget *gadget,
		struct usb_gadget_driver *driver)
{
	struct at91_udc *udc = controller;

	udc->driver = driver;
	udc->enabled = 1;
	udc->selfpowered = 1;

	return 0;
}

static int at91_stop(struct usb_gadget *gadget)
{
	struct at91_udc *udc = controller;
	unsigned long	flags;

	spin_lock_irqsave(&udc->lock, flags);
	udc->enabled = 0;
	at91_udp_write(udc, AT91_UDP_IDR, ~0);
	spin_unlock_irqrestore(&udc->lock, flags);

	udc->driver = NULL;

	return 0;
}

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

static int at91rm9200_udc_init(struct at91_udc *udc)
{
	struct at91_ep *ep;
	int ret;
	int i;

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

		switch (i) {
		case 0:
		case 3:
			ep->maxpacket = 8;
			break;
		case 1 ... 2:
			ep->maxpacket = 64;
			break;
		case 4 ... 5:
			ep->maxpacket = 256;
			break;
		}
	}

	ret = gpio_request(udc->board.pullup_pin, "udc_pullup");
	if (ret) {
		DBG("D+ pullup is busy\n");
		return ret;
	}

	gpio_direction_output(udc->board.pullup_pin,
			      udc->board.pullup_active_low);

	return 0;
}

static void at91rm9200_udc_pullup(struct at91_udc *udc, int is_on)
{
	int active = !udc->board.pullup_active_low;

	if (is_on)
		gpio_set_value(udc->board.pullup_pin, active);
	else
		gpio_set_value(udc->board.pullup_pin, !active);
}

static const struct at91_udc_caps at91rm9200_udc_caps = {
	.init = at91rm9200_udc_init,
	.pullup = at91rm9200_udc_pullup,
};

static int at91sam9260_udc_init(struct at91_udc *udc)
{
	struct at91_ep *ep;
	int i;

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

		switch (i) {
		case 0 ... 3:
			ep->maxpacket = 64;
			break;
		case 4 ... 5:
			ep->maxpacket = 512;
			break;
		}
	}

	return 0;
}

#if defined(CONFIG_AT91SAM9260) || defined(CONFIG_AT91SAM9G20)
static void at91sam9260_udc_pullup(struct at91_udc *udc, int is_on)
{
	u32 txvc = at91_udp_read(udc, AT91_UDP_TXVC);

	if (is_on)
		txvc |= AT91_UDP_TXVC_PUON;
	else
		txvc &= ~AT91_UDP_TXVC_PUON;

	at91_udp_write(udc, AT91_UDP_TXVC, txvc);
}

static const struct at91_udc_caps at91sam9260_udc_caps = {
	.init = at91sam9260_udc_init,
	.pullup = at91sam9260_udc_pullup,
};
#endif

#if defined(CONFIG_AT91SAM9261)
static int at91sam9261_udc_init(struct at91_udc *udc)
{
	struct at91_ep *ep;
	int i;

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

		switch (i) {
		case 0:
			ep->maxpacket = 8;
			break;
		case 1 ... 3:
			ep->maxpacket = 64;
			break;
		case 4 ... 5:
			ep->maxpacket = 256;
			break;
		}
	}

	udc->matrix = (struct at91_matrix *)ATMEL_BASE_MATRIX;

	if (IS_ERR(udc->matrix))
		return PTR_ERR(udc->matrix);

	return 0;
}

static void at91sam9261_udc_pullup(struct at91_udc *udc, int is_on)
{
	u32 usbpucr = 0;

	usbpucr = readl(&udc->matrix->pucr);
	if (is_on)
		usbpucr |= AT91_MATRIX_USBPUCR_PUON;

	writel(usbpucr, &udc->matrix->pucr);
}

static const struct at91_udc_caps at91sam9261_udc_caps = {
	.init = at91sam9261_udc_init,
	.pullup = at91sam9261_udc_pullup,
};
#endif

static int at91sam9263_udc_init(struct at91_udc *udc)
{
	struct at91_ep *ep;
	int i;

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

		switch (i) {
		case 0:
		case 1:
		case 2:
		case 3:
			ep->maxpacket = 64;
			break;
		case 4:
		case 5:
			ep->maxpacket = 256;
			break;
		}
	}

	return 0;
}

static const struct at91_udc_caps at91sam9263_udc_caps = {
	.init = at91sam9263_udc_init,
	.pullup = at91sam9260_udc_pullup,
};

int usb_gadget_handle_interrupts(int index)
{
	struct at91_udc *udc = controller;

	return at91_udc_irq(udc);
}

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

	if (!driver || !driver->bind || !driver->setup) {
		printf("bad paramter\n");
		return -EINVAL;
	}

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

	at91_start(&udc->gadget, driver);

	udc->driver = driver;

	ret = driver->bind(&udc->gadget);
	if (ret) {
		error("driver->bind() returned %d\n", ret);
		udc->driver = NULL;
	}

	return ret;
}

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

	if (!driver || !driver->unbind || !driver->disconnect) {
		error("bad paramter\n");
		return -EINVAL;
	}

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

	at91_stop(&udc->gadget);

	return 0;
}

int at91_udc_probe(struct at91_udc_data *pdata)
{
	struct at91_udc	*udc;
	int		retval;
	struct at91_ep	*ep;
	int		i;

	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
	if (!udc)
		return -ENOMEM;

	controller = udc;
	memcpy(&udc->board, pdata, sizeof(struct at91_udc_data));
	if (udc->board.vbus_pin) {
		printf("%s: gpio vbus pin not supported yet.\n", __func__);
		return -ENXIO;
	} else {
		DBG("no VBUS detection, assuming always-on\n");
		udc->vbus = 1;
	}

#if defined(CONFIG_AT91SAM9260) || defined(CONFIG_AT91SAM9G20)
	udc->caps = &at91sam9260_udc_caps;
#endif

	udc->enabled = 0;
	spin_lock_init(&udc->lock);

	udc->gadget.ops = &at91_udc_ops;
	udc->gadget.ep0 = &udc->ep[0].ep;
	udc->gadget.name = driver_name;

	for (i = 0; i < NUM_ENDPOINTS; i++) {
		ep = &udc->ep[i];
		ep->ep.name = ep_names[i];
		ep->ep.ops = &at91_ep_ops;
		ep->udc = udc;
		ep->int_mask = (1 << i);
		if (i != 0 && i != 3)
			ep->is_pingpong = 1;
	}

	udc->udp_baseaddr = (void *)udc->board.baseaddr;
	if (IS_ERR(udc->udp_baseaddr))
		return PTR_ERR(udc->udp_baseaddr);

	if (udc->caps && udc->caps->init) {
		retval = udc->caps->init(udc);
		if (retval)
			return retval;
	}

	udc_reinit(udc);

	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);

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