[PATCH] USB: add support for AT91 gadget

This adds support for the USB peripheral controller on AT91
(rm9200, eventually also sam9261 or uClinux) platforms.

More SOC support for Linux-USB ... an uncomplicated pure PIO driver.
It'd be worth using this as a model, if you're starting a driver
for some other peripheral controller.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1773 insertions, 0 deletions

diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c
new file mode 100644
index 0000000..865858c
--- /dev/null
+++ b/drivers/usb/gadget/at91_udc.c
@@ -0,0 +1,1773 @@
+/*
+ * 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/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/ioport.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.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/io.h>
+#include <asm/irq.h>
+#include <asm/system.h>
+#include <asm/mach-types.h>
+
+#include <asm/arch/hardware.h>
+#include <asm/arch/gpio.h>
+#include <asm/arch/board.h>
+
+#include "at91_udc.h"
+
+
+/*
+ * This controller is simple and PIO-only.  It's used in many AT91-series
+ * ARMv4T controllers, including the at91rm9200 (arm920T, with MMU),
+ * at91sam9261 (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; 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.
+ */
+
+#define	DRIVER_VERSION	"8 March 2005"
+
+static const char driver_name [] = "at91_udc";
+static const char ep0name[] = "ep0";
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Read from a UDP register.
+ */
+static inline unsigned long at91_udp_read(unsigned int reg)
+{
+	void __iomem *udp_base = (void __iomem *)AT91_VA_BASE_UDP;
+
+	return __raw_readl(udp_base + reg);
+}
+
+/*
+ * Write to a UDP register.
+ */
+static inline void at91_udp_write(unsigned int reg, unsigned long value)
+{
+	void __iomem *udp_base = (void __iomem *)AT91_VA_BASE_UDP;
+
+	__raw_writel(value, udp_base + 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(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(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(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(AT91_UDP_IMR));
+	proc_irq_show(s, "isr   ", at91_udp_read(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 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;
+
+	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(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.
+ */
+#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(AT91_UDP_RST_EP, ep->int_mask);
+	at91_udp_write(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);
+	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(AT91_UDP_RST_EP, ep->int_mask);
+		at91_udp_write(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 = kcalloc(1, sizeof (struct at91_request), SLAB_KERNEL);
+	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 void *at91_ep_alloc_buffer(
+	struct usb_ep *_ep,
+	unsigned bytes,
+	dma_addr_t *dma,
+	gfp_t gfp_flags)
+{
+	*dma = ~0;
+	return kmalloc(bytes, gfp_flags);
+}
+
+static void at91_ep_free_buffer(
+	struct usb_ep *ep,
+	void *buf,
+	dma_addr_t dma,
+	unsigned bytes)
+{
+	kfree(buf);
+}
+
+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(AT91_UDP_GLB_STAT);
+				tmp ^= AT91_UDP_CONFG;
+				VDBG("toggle config\n");
+				at91_udp_write(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(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);
+	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(AT91_UDP_RST_EP, ep->int_mask);
+			at91_udp_write(AT91_UDP_RST_EP, 0);
+			csr &= ~AT91_UDP_FORCESTALL;
+		}
+		__raw_writel(csr, creg);
+	}
+
+	local_irq_restore(flags);
+	return status;
+}
+
+static 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,
+	.alloc_buffer	= at91_ep_alloc_buffer,
+	.free_buffer	= at91_ep_free_buffer,
+	.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)
+{
+	if (!to_udc(gadget)->clocked)
+		return -EINVAL;
+	return at91_udp_read(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(AT91_UDP_GLB_STAT);
+	if (!(glbstate & AT91_UDP_ESR))
+		goto done;
+	glbstate |= AT91_UDP_ESR;
+	at91_udp_write(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;
+		// 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;
+
+	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->iclk);
+	clk_disable(udc->fclk);
+}
+
+/*
+ * 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(AT91_UDP_TXVC, 0);
+		at91_set_gpio_value(udc->board.pullup_pin, 1);
+	} else  {
+		stop_activity(udc);
+		at91_udp_write(AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
+		at91_set_gpio_value(udc->board.pullup_pin, 0);
+		clk_off(udc);
+
+		// REVISIT:  with transceiver disabled, will D- float
+		// so that a host would falsely detect a device?
+	}
+}
+
+/* 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);
+	pullup(udc, is_active);
+	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(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(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(AT91_UDP_GLB_STAT);
+		tmp |= AT91_UDP_ESR;
+		at91_udp_write(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(AT91_UDP_GLB_STAT);
+		tmp &= ~AT91_UDP_ESR;
+		at91_udp_write(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(AT91_UDP_RST_EP, ep->int_mask);
+		at91_udp_write(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 */
+	status = udc->driver->setup(&udc->gadget, &pkt.r);
+	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(AT91_UDP_FADDR, AT91_UDP_FEN | udc->addr);
+				tmp = at91_udp_read(AT91_UDP_GLB_STAT);
+				tmp &= ~AT91_UDP_FADDEN;
+				if (udc->addr)
+					tmp |= AT91_UDP_FADDEN;
+				at91_udp_write(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 pt_regs *r)
+{
+	struct at91_udc		*udc = _udc;
+	u32			rescans = 5;
+
+	while (rescans--) {
+		u32	status = at91_udp_read(AT91_UDP_ISR);
+
+		status &= at91_udp_read(AT91_UDP_IMR);
+		if (!status)
+			break;
+
+		/* USB reset irq:  not maskable */
+		if (status & AT91_UDP_ENDBUSRES) {
+			at91_udp_write(AT91_UDP_IDR, ~MINIMUS_INTERRUPTUS);
+			at91_udp_write(AT91_UDP_IER, MINIMUS_INTERRUPTUS);
+			/* Atmel code clears this irq twice */
+			at91_udp_write(AT91_UDP_ICR, AT91_UDP_ENDBUSRES);
+			at91_udp_write(AT91_UDP_ICR, AT91_UDP_ENDBUSRES);
+			VDBG("end bus reset\n");
+			udc->addr = 0;
+			stop_activity(udc);
+
+			/* enable ep0 */
+			at91_udp_write(AT91_UDP_CSR(0), AT91_UDP_EPEDS | AT91_UDP_EPTYPE_CTRL);
+			udc->gadget.speed = USB_SPEED_FULL;
+			udc->suspended = 0;
+			at91_udp_write(AT91_UDP_IER, AT91_UDP_EP(0));
+
+			/*
+			 * NOTE:  this driver keeps clocks off unless the
+			 * USB host is present.  That saves power, and also
+			 * eliminates IRQs (reset, resume, suspend) that can
+			 * otherwise flood from the controller.  If your
+			 * board doesn't support VBUS detection, suspend and
+			 * resume irq logic may need more attention...
+			 */
+
+		/* host initiated suspend (3+ms bus idle) */
+		} else if (status & AT91_UDP_RXSUSP) {
+			at91_udp_write(AT91_UDP_IDR, AT91_UDP_RXSUSP);
+			at91_udp_write(AT91_UDP_IER, AT91_UDP_RXRSM);
+			at91_udp_write(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(AT91_UDP_IDR, AT91_UDP_RXRSM);
+			at91_udp_write(AT91_UDP_IER, AT91_UDP_RXSUSP);
+			at91_udp_write(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 struct at91_udc controller = {
+	.gadget = {
+		.ops = &at91_udc_ops,
+		.ep0 = &controller.ep[0].ep,
+		.name = driver_name,
+		.dev = {
+			.bus_id = "gadget"
+		}
+	},
+	.ep[0] = {
+		.ep = {
+			.name	= ep0name,
+			.ops	= &at91_ep_ops,
+		},
+		.udc		= &controller,
+		.maxpacket	= 8,
+		.creg		= (void __iomem *)(AT91_VA_BASE_UDP + AT91_UDP_CSR(0)),
+		.int_mask	= 1 << 0,
+	},
+	.ep[1] = {
+		.ep = {
+			.name	= "ep1",
+			.ops	= &at91_ep_ops,
+		},
+		.udc		= &controller,
+		.is_pingpong	= 1,
+		.maxpacket	= 64,
+		.creg		= (void __iomem *)(AT91_VA_BASE_UDP + AT91_UDP_CSR(1)),
+		.int_mask	= 1 << 1,
+	},
+	.ep[2] = {
+		.ep = {
+			.name	= "ep2",
+			.ops	= &at91_ep_ops,
+		},
+		.udc		= &controller,
+		.is_pingpong	= 1,
+		.maxpacket	= 64,
+		.creg		= (void __iomem *)(AT91_VA_BASE_UDP + AT91_UDP_CSR(2)),
+		.int_mask	= 1 << 2,
+	},
+	.ep[3] = {
+		.ep = {
+			/* could actually do bulk too */
+			.name	= "ep3-int",
+			.ops	= &at91_ep_ops,
+		},
+		.udc		= &controller,
+		.maxpacket	= 8,
+		.creg		= (void __iomem *)(AT91_VA_BASE_UDP + AT91_UDP_CSR(3)),
+		.int_mask	= 1 << 3,
+	},
+	.ep[4] = {
+		.ep = {
+			.name	= "ep4",
+			.ops	= &at91_ep_ops,
+		},
+		.udc		= &controller,
+		.is_pingpong	= 1,
+		.maxpacket	= 256,
+		.creg		= (void __iomem *)(AT91_VA_BASE_UDP + AT91_UDP_CSR(4)),
+		.int_mask	= 1 << 4,
+	},
+	.ep[5] = {
+		.ep = {
+			.name	= "ep5",
+			.ops	= &at91_ep_ops,
+		},
+		.udc		= &controller,
+		.is_pingpong	= 1,
+		.maxpacket	= 256,
+		.creg		= (void __iomem *)(AT91_VA_BASE_UDP + AT91_UDP_CSR(5)),
+		.int_mask	= 1 << 5,
+	},
+	/* ep6 and ep7 are also reserved */
+};
+
+static irqreturn_t at91_vbus_irq(int irq, void *_udc, struct pt_regs *r)
+{
+	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->unbind
+			|| !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;
+		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)
+		return -EINVAL;
+
+	local_irq_disable();
+	udc->enabled = 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 __devinit at91udc_probe(struct platform_device *pdev)
+{
+	struct device	*dev = &pdev->dev;
+	struct at91_udc	*udc;
+	int		retval;
+
+	if (!dev->platform_data) {
+		/* small (so we copy it) but critical! */
+		DBG("missing platform_data\n");
+		return -ENODEV;
+	}
+
+	if (!request_mem_region(AT91_BASE_UDP, SZ_16K, 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_reinit(udc);
+	udc->enabled = 0;
+
+	/* 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");
+		return -ENODEV;
+	}
+
+	retval = device_register(&udc->gadget.dev);
+	if (retval < 0)
+		goto fail0;
+
+	/* disable everything until there's a gadget driver and vbus */
+	pullup(udc, 0);
+
+	/* request UDC and maybe VBUS irqs */
+	if (request_irq(AT91_ID_UDP, at91_udc_irq, SA_INTERRUPT, driver_name, udc)) {
+		DBG("request irq %d failed\n", AT91_ID_UDP);
+		retval = -EBUSY;
+		goto fail1;
+	}
+	if (udc->board.vbus_pin > 0) {
+		if (request_irq(udc->board.vbus_pin, at91_vbus_irq, SA_INTERRUPT, driver_name, udc)) {
+			DBG("request vbus irq %d failed\n", udc->board.vbus_pin);
+			free_irq(AT91_ID_UDP, udc);
+			retval = -EBUSY;
+			goto fail1;
+		}
+	} else {
+		DBG("no VBUS detection, assuming always-on\n");
+		udc->vbus = 1;
+	}
+	dev_set_drvdata(dev, udc);
+	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(AT91_VA_BASE_UDP, SZ_16K);
+	DBG("%s probe failed, %d\n", driver_name, retval);
+	return retval;
+}
+
+static int __devexit at91udc_remove(struct platform_device *dev)
+{
+	struct at91_udc *udc = platform_get_drvdata(dev);
+
+	DBG("remove\n");
+
+	pullup(udc, 0);
+
+	if (udc->driver != 0)
+		usb_gadget_unregister_driver(udc->driver);
+
+	remove_debug_file(udc);
+	if (udc->board.vbus_pin > 0)
+		free_irq(udc->board.vbus_pin, udc);
+	free_irq(AT91_ID_UDP, udc);
+	device_unregister(&udc->gadget.dev);
+	release_mem_region(AT91_BASE_UDP, SZ_16K);
+
+	clk_put(udc->iclk);
+	clk_put(udc->fclk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int at91udc_suspend(struct platform_device *dev, u32 state, u32 level)
+{
+	struct at91_udc *udc = platform_get_drvdata(dev);
+
+	/*
+	 * The "safe" suspend transitions are opportunistic ... e.g. when
+	 * the USB link is suspended (48MHz clock autogated off), or when
+	 * it's disconnected (programmatically gated off, elsewhere).
+	 * Then we can suspend, and the chip can enter slow clock mode.
+	 *
+	 * The problem case is some component (user mode?) suspending this
+	 * device while it's active, with the 48 MHz clock in use.  There
+	 * are two basic approaches:  (a) veto suspend levels involving slow
+	 * clock mode, (b) disconnect, so 48 MHz will no longer be in use
+	 * and we can enter slow clock mode.  This uses (b) for now, since
+	 * it's simplest until AT91 PM exists and supports the other option.
+	 */
+	if (udc->vbus && !udc->suspended)
+		pullup(udc, 0);
+	return 0;
+}
+
+static int at91udc_resume(struct platform_device *dev, u32 level)
+{
+	struct at91_udc *udc = platform_get_drvdata(dev);
+
+	/* maybe reconnect to host; if so, clocks on */
+	pullup(udc, 1);
+	return 0;
+}
+#else
+#define	at91udc_suspend	NULL
+#define	at91udc_resume	NULL
+#endif
+
+static struct platform_driver at91_udc = {
+	.probe		= at91udc_probe,
+	.remove		= __devexit_p(at91udc_remove),
+	.shutdown	= at91udc_shutdown,
+	.suspend	= at91udc_suspend,
+	.resume 	= at91udc_resume,
+	.driver		= {
+		.name	= (char *) driver_name,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __devinit udc_init_module(void)
+{
+	return platform_driver_register(&at91_udc);
+}
+module_init(udc_init_module);
+
+static void __devexit udc_exit_module(void)
+{
+	platform_driver_unregister(&at91_udc);
+}
+module_exit(udc_exit_module);
+
+MODULE_DESCRIPTION("AT91RM9200 udc driver");
+MODULE_AUTHOR("Thomas Rathbone, David Brownell");
+MODULE_LICENSE("GPL");