usb: gadget: Add UDC driver for Aeroflex Gaisler GRUSBDC

This adds an UDC driver for GRUSBDC USB Device Controller cores available in the
GRLIB VHDL IP core library. The driver only supports DMA mode.

Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

4 files changed, 2470 insertions, 0 deletions

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index fbc5607c8cd3..8154165aa601 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -216,6 +216,13 @@ config USB_FOTG210_UDC
 	   Say "y" to link the driver statically, or "m" to build a
 	   dynamically linked module called "fotg210_udc".
 
+config USB_GR_UDC
+       tristate "Aeroflex Gaisler GRUSBDC USB Peripheral Controller Driver"
+       depends on HAS_DMA
+       help
+          Select this to support Aeroflex Gaisler GRUSBDC cores from the GRLIB
+	  VHDL IP core library.
+
 config USB_OMAP
 	tristate "OMAP USB Device Controller"
 	depends on ARCH_OMAP1
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 6cccdfed140c..5f150bc1b4bc 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -35,6 +35,7 @@ mv_udc-y			:= mv_udc_core.o
 obj-$(CONFIG_USB_FUSB300)	+= fusb300_udc.o
 obj-$(CONFIG_USB_FOTG210_UDC)	+= fotg210-udc.o
 obj-$(CONFIG_USB_MV_U3D)	+= mv_u3d_core.o
+obj-$(CONFIG_USB_GR_UDC)	+= gr_udc.o
 
 # USB Functions
 usb_f_acm-y			:= f_acm.o
diff --git a/drivers/usb/gadget/gr_udc.c b/drivers/usb/gadget/gr_udc.c
new file mode 100644
index 000000000000..5f9c65959dd2
--- /dev/null
+++ b/drivers/usb/gadget/gr_udc.c
@@ -0,0 +1,2242 @@
+/*
+ * USB Peripheral Controller driver for Aeroflex Gaisler GRUSBDC.
+ *
+ * 2013 (c) Aeroflex Gaisler AB
+ *
+ * This driver supports GRUSBDC USB Device Controller cores available in the
+ * GRLIB VHDL IP core library.
+ *
+ * Full documentation of the GRUSBDC core can be found here:
+ * http://www.gaisler.com/products/grlib/grip.pdf
+ *
+ * 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.
+ *
+ * Contributors:
+ * - Andreas Larsson <andreas@gaisler.com>
+ * - Marko Isomaki
+ */
+
+/*
+ * A GRUSBDC core can have up to 16 IN endpoints and 16 OUT endpoints each
+ * individually configurable to any of the four USB transfer types. This driver
+ * only supports cores in DMA mode.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/of_platform.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+
+#include <asm/byteorder.h>
+
+#include "gr_udc.h"
+
+#define	DRIVER_NAME	"gr_udc"
+#define	DRIVER_DESC	"Aeroflex Gaisler GRUSBDC USB Peripheral Controller"
+
+static const char driver_name[] = DRIVER_NAME;
+static const char driver_desc[] = DRIVER_DESC;
+
+#define gr_read32(x) (ioread32be((x)))
+#define gr_write32(x, v) (iowrite32be((v), (x)))
+
+/* USB speed and corresponding string calculated from status register value */
+#define GR_SPEED(status) \
+	((status & GR_STATUS_SP) ? USB_SPEED_FULL : USB_SPEED_HIGH)
+#define GR_SPEED_STR(status) usb_speed_string(GR_SPEED(status))
+
+/* Size of hardware buffer calculated from epctrl register value */
+#define GR_BUFFER_SIZE(epctrl)					      \
+	((((epctrl) & GR_EPCTRL_BUFSZ_MASK) >> GR_EPCTRL_BUFSZ_POS) * \
+	 GR_EPCTRL_BUFSZ_SCALER)
+
+/* ---------------------------------------------------------------------- */
+/* Debug printout functionality */
+
+static const char * const gr_modestring[] = {"control", "iso", "bulk", "int"};
+
+static const char *gr_ep0state_string(enum gr_ep0state state)
+{
+	static const char *const names[] = {
+		[GR_EP0_DISCONNECT] = "disconnect",
+		[GR_EP0_SETUP] = "setup",
+		[GR_EP0_IDATA] = "idata",
+		[GR_EP0_ODATA] = "odata",
+		[GR_EP0_ISTATUS] = "istatus",
+		[GR_EP0_OSTATUS] = "ostatus",
+		[GR_EP0_STALL] = "stall",
+		[GR_EP0_SUSPEND] = "suspend",
+	};
+
+	if (state < 0 || state >= ARRAY_SIZE(names))
+		return "UNKNOWN";
+
+	return names[state];
+}
+
+#ifdef VERBOSE_DEBUG
+
+static void gr_dbgprint_request(const char *str, struct gr_ep *ep,
+				struct gr_request *req)
+{
+	int buflen = ep->is_in ? req->req.length : req->req.actual;
+	int rowlen = 32;
+	int plen = min(rowlen, buflen);
+
+	dev_dbg(ep->dev->dev, "%s: 0x%p, %d bytes data%s:\n", str, req, buflen,
+		(buflen > plen ? " (truncated)" : ""));
+	print_hex_dump_debug("   ", DUMP_PREFIX_NONE,
+			     rowlen, 4, req->req.buf, plen, false);
+}
+
+static void gr_dbgprint_devreq(struct gr_udc *dev, u8 type, u8 request,
+			       u16 value, u16 index, u16 length)
+{
+	dev_vdbg(dev->dev, "REQ: %02x.%02x v%04x i%04x l%04x\n",
+		 type, request, value, index, length);
+}
+#else /* !VERBOSE_DEBUG */
+
+static void gr_dbgprint_request(const char *str, struct gr_ep *ep,
+				struct gr_request *req) {}
+
+static void gr_dbgprint_devreq(struct gr_udc *dev, u8 type, u8 request,
+			       u16 value, u16 index, u16 length) {}
+
+#endif /* VERBOSE_DEBUG */
+
+/* ---------------------------------------------------------------------- */
+/* Debugfs functionality */
+
+#ifdef CONFIG_USB_GADGET_DEBUG_FS
+
+static void gr_seq_ep_show(struct seq_file *seq, struct gr_ep *ep)
+{
+	u32 epctrl = gr_read32(&ep->regs->epctrl);
+	u32 epstat = gr_read32(&ep->regs->epstat);
+	int mode = (epctrl & GR_EPCTRL_TT_MASK) >> GR_EPCTRL_TT_POS;
+	struct gr_request *req;
+
+	seq_printf(seq, "%s:\n", ep->ep.name);
+	seq_printf(seq, "  mode = %s\n", gr_modestring[mode]);
+	seq_printf(seq, "  halted: %d\n", !!(epctrl & GR_EPCTRL_EH));
+	seq_printf(seq, "  disabled: %d\n", !!(epctrl & GR_EPCTRL_ED));
+	seq_printf(seq, "  valid: %d\n", !!(epctrl & GR_EPCTRL_EV));
+	seq_printf(seq, "  dma_start = %d\n", ep->dma_start);
+	seq_printf(seq, "  stopped = %d\n", ep->stopped);
+	seq_printf(seq, "  wedged = %d\n", ep->wedged);
+	seq_printf(seq, "  callback = %d\n", ep->callback);
+	seq_printf(seq, "  maxpacket = %d\n", ep->ep.maxpacket);
+	seq_printf(seq, "  bytes_per_buffer = %d\n", ep->bytes_per_buffer);
+	if (mode == 1 || mode == 3)
+		seq_printf(seq, "  nt = %d\n",
+			   (epctrl & GR_EPCTRL_NT_MASK) >> GR_EPCTRL_NT_POS);
+
+	seq_printf(seq, "  Buffer 0: %s %s%d\n",
+		   epstat & GR_EPSTAT_B0 ? "valid" : "invalid",
+		   epstat & GR_EPSTAT_BS ? " " : "selected ",
+		   (epstat & GR_EPSTAT_B0CNT_MASK) >> GR_EPSTAT_B0CNT_POS);
+	seq_printf(seq, "  Buffer 1: %s %s%d\n",
+		   epstat & GR_EPSTAT_B1 ? "valid" : "invalid",
+		   epstat & GR_EPSTAT_BS ? "selected " : " ",
+		   (epstat & GR_EPSTAT_B1CNT_MASK) >> GR_EPSTAT_B1CNT_POS);
+
+	if (list_empty(&ep->queue)) {
+		seq_puts(seq, "  Queue: empty\n\n");
+		return;
+	}
+
+	seq_puts(seq, "  Queue:\n");
+	list_for_each_entry(req, &ep->queue, queue) {
+		struct gr_dma_desc *desc;
+		struct gr_dma_desc *next;
+
+		seq_printf(seq, "    0x%p: 0x%p %d %d\n", req,
+			   &req->req.buf, req->req.actual, req->req.length);
+
+		next = req->first_desc;
+		do {
+			desc = next;
+			next = desc->next_desc;
+			seq_printf(seq, "    %c 0x%p (0x%08x): 0x%05x 0x%08x\n",
+				   desc == req->curr_desc ? 'c' : ' ',
+				   desc, desc->paddr, desc->ctrl, desc->data);
+		} while (desc != req->last_desc);
+	}
+	seq_puts(seq, "\n");
+}
+
+
+static int gr_seq_show(struct seq_file *seq, void *v)
+{
+	struct gr_udc *dev = seq->private;
+	u32 control = gr_read32(&dev->regs->control);
+	u32 status = gr_read32(&dev->regs->status);
+	struct gr_ep *ep;
+
+	seq_printf(seq, "usb state = %s\n",
+		   usb_state_string(dev->gadget.state));
+	seq_printf(seq, "address = %d\n",
+		   (control & GR_CONTROL_UA_MASK) >> GR_CONTROL_UA_POS);
+	seq_printf(seq, "speed = %s\n", GR_SPEED_STR(status));
+	seq_printf(seq, "ep0state = %s\n", gr_ep0state_string(dev->ep0state));
+	seq_printf(seq, "irq_enabled = %d\n", dev->irq_enabled);
+	seq_printf(seq, "remote_wakeup = %d\n", dev->remote_wakeup);
+	seq_printf(seq, "test_mode = %d\n", dev->test_mode);
+	seq_puts(seq, "\n");
+
+	list_for_each_entry(ep, &dev->ep_list, ep_list)
+		gr_seq_ep_show(seq, ep);
+
+	return 0;
+}
+
+static int gr_dfs_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, gr_seq_show, inode->i_private);
+}
+
+static const struct file_operations gr_dfs_fops = {
+	.owner		= THIS_MODULE,
+	.open		= gr_dfs_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static void gr_dfs_create(struct gr_udc *dev)
+{
+	const char *name = "gr_udc_state";
+
+	dev->dfs_root = debugfs_create_dir(dev_name(dev->dev), NULL);
+	if (IS_ERR(dev->dfs_root)) {
+		dev_err(dev->dev, "Failed to create debugfs directory\n");
+		return;
+	}
+	dev->dfs_state = debugfs_create_file(name, 0444, dev->dfs_root,
+					     dev, &gr_dfs_fops);
+	if (IS_ERR(dev->dfs_state))
+		dev_err(dev->dev, "Failed to create debugfs file %s\n", name);
+}
+
+static void gr_dfs_delete(struct gr_udc *dev)
+{
+	/* Handles NULL and ERR pointers internally */
+	debugfs_remove(dev->dfs_state);
+	debugfs_remove(dev->dfs_root);
+}
+
+#else /* !CONFIG_USB_GADGET_DEBUG_FS */
+
+static void gr_dfs_create(struct gr_udc *dev) {}
+static void gr_dfs_delete(struct gr_udc *dev) {}
+
+#endif /* CONFIG_USB_GADGET_DEBUG_FS */
+
+/* ---------------------------------------------------------------------- */
+/* DMA and request handling */
+
+/* Allocates a new struct gr_dma_desc, sets paddr and zeroes the rest */
+static struct gr_dma_desc *gr_alloc_dma_desc(struct gr_ep *ep, gfp_t gfp_flags)
+{
+	dma_addr_t paddr;
+	struct gr_dma_desc *dma_desc;
+
+	dma_desc = dma_pool_alloc(ep->dev->desc_pool, gfp_flags, &paddr);
+	if (!dma_desc) {
+		dev_err(ep->dev->dev, "Could not allocate from DMA pool\n");
+		return NULL;
+	}
+
+	memset(dma_desc, 0, sizeof(*dma_desc));
+	dma_desc->paddr = paddr;
+
+	return dma_desc;
+}
+
+static inline void gr_free_dma_desc(struct gr_udc *dev,
+				    struct gr_dma_desc *desc)
+{
+	dma_pool_free(dev->desc_pool, desc, (dma_addr_t)desc->paddr);
+}
+
+/* Frees the chain of struct gr_dma_desc for the given request */
+static void gr_free_dma_desc_chain(struct gr_udc *dev, struct gr_request *req)
+{
+	struct gr_dma_desc *desc;
+	struct gr_dma_desc *next;
+
+	next = req->first_desc;
+	if (!next)
+		return;
+
+	do {
+		desc = next;
+		next = desc->next_desc;
+		gr_free_dma_desc(dev, desc);
+	} while (desc != req->last_desc);
+
+	req->first_desc = NULL;
+	req->curr_desc = NULL;
+	req->last_desc = NULL;
+}
+
+static void gr_ep0_setup(struct gr_udc *dev, struct gr_request *req);
+
+/*
+ * Frees allocated resources and calls the appropriate completion function/setup
+ * package handler for a finished request.
+ *
+ * Must be called with dev->lock held and irqs disabled.
+ */
+static void gr_finish_request(struct gr_ep *ep, struct gr_request *req,
+			      int status)
+	__releases(&dev->lock)
+	__acquires(&dev->lock)
+{
+	struct gr_udc *dev;
+
+	list_del_init(&req->queue);
+
+	if (likely(req->req.status == -EINPROGRESS))
+		req->req.status = status;
+	else
+		status = req->req.status;
+
+	dev = ep->dev;
+	usb_gadget_unmap_request(&dev->gadget, &req->req, ep->is_in);
+	gr_free_dma_desc_chain(dev, req);
+
+	if (ep->is_in) /* For OUT, actual gets updated bit by bit */
+		req->req.actual = req->req.length;
+
+	if (!status) {
+		if (ep->is_in)
+			gr_dbgprint_request("SENT", ep, req);
+		else
+			gr_dbgprint_request("RECV", ep, req);
+	}
+
+	/* Prevent changes to ep->queue during callback */
+	ep->callback = 1;
+	if (req == dev->ep0reqo && !status) {
+		if (req->setup)
+			gr_ep0_setup(dev, req);
+		else
+			dev_err(dev->dev,
+				"Unexpected non setup packet on ep0in\n");
+	} else if (req->req.complete) {
+		spin_unlock(&dev->lock);
+
+		req->req.complete(&ep->ep, &req->req);
+
+		spin_lock(&dev->lock);
+	}
+	ep->callback = 0;
+}
+
+static struct usb_request *gr_alloc_request(struct usb_ep *_ep, gfp_t gfp_flags)
+{
+	struct gr_request *req;
+
+	req = kzalloc(sizeof(*req), gfp_flags);
+	if (!req)
+		return NULL;
+
+	INIT_LIST_HEAD(&req->queue);
+
+	return &req->req;
+}
+
+/*
+ * Starts DMA for endpoint ep if there are requests in the queue.
+ *
+ * Must be called with dev->lock held and with !ep->stopped.
+ */
+static void gr_start_dma(struct gr_ep *ep)
+{
+	struct gr_request *req;
+	u32 dmactrl;
+
+	if (list_empty(&ep->queue)) {
+		ep->dma_start = 0;
+		return;
+	}
+
+	req = list_first_entry(&ep->queue, struct gr_request, queue);
+
+	/* A descriptor should already have been allocated */
+	BUG_ON(!req->curr_desc);
+
+	wmb(); /* Make sure all is settled before handing it over to DMA */
+
+	/* Set the descriptor pointer in the hardware */
+	gr_write32(&ep->regs->dmaaddr, req->curr_desc->paddr);
+
+	/* Announce available descriptors */
+	dmactrl = gr_read32(&ep->regs->dmactrl);
+	gr_write32(&ep->regs->dmactrl, dmactrl | GR_DMACTRL_DA);
+
+	ep->dma_start = 1;
+}
+
+/*
+ * Finishes the first request in the ep's queue and, if available, starts the
+ * next request in queue.
+ *
+ * Must be called with dev->lock held, irqs disabled and with !ep->stopped.
+ */
+static void gr_dma_advance(struct gr_ep *ep, int status)
+{
+	struct gr_request *req;
+
+	req = list_first_entry(&ep->queue, struct gr_request, queue);
+	gr_finish_request(ep, req, status);
+	gr_start_dma(ep); /* Regardless of ep->dma_start */
+}
+
+/*
+ * Abort DMA for an endpoint. Sets the abort DMA bit which causes an ongoing DMA
+ * transfer to be canceled and clears GR_DMACTRL_DA.
+ *
+ * Must be called with dev->lock held.
+ */
+static void gr_abort_dma(struct gr_ep *ep)
+{
+	u32 dmactrl;
+
+	dmactrl = gr_read32(&ep->regs->dmactrl);
+	gr_write32(&ep->regs->dmactrl, dmactrl | GR_DMACTRL_AD);
+}
+
+/*
+ * Allocates and sets up a struct gr_dma_desc and putting it on the descriptor
+ * chain.
+ *
+ * Size is not used for OUT endpoints. Hardware can not be instructed to handle
+ * smaller buffer than MAXPL in the OUT direction.
+ */
+static int gr_add_dma_desc(struct gr_ep *ep, struct gr_request *req,
+			   dma_addr_t data, unsigned size, gfp_t gfp_flags)
+{
+	struct gr_dma_desc *desc;
+
+	desc = gr_alloc_dma_desc(ep, gfp_flags);
+	if (!desc)
+		return -ENOMEM;
+
+	desc->data = data;
+	if (ep->is_in)
+		desc->ctrl =
+			(GR_DESC_IN_CTRL_LEN_MASK & size) | GR_DESC_IN_CTRL_EN;
+	else
+		desc->ctrl = GR_DESC_OUT_CTRL_IE;
+
+	if (!req->first_desc) {
+		req->first_desc = desc;
+		req->curr_desc = desc;
+	} else {
+		req->last_desc->next_desc = desc;
+		req->last_desc->next = desc->paddr;
+		req->last_desc->ctrl |= GR_DESC_OUT_CTRL_NX;
+	}
+	req->last_desc = desc;
+
+	return 0;
+}
+
+/*
+ * Sets up a chain of struct gr_dma_descriptors pointing to buffers that
+ * together covers req->req.length bytes of the buffer at DMA address
+ * req->req.dma for the OUT direction.
+ *
+ * The first descriptor in the chain is enabled, the rest disabled. The
+ * interrupt handler will later enable them one by one when needed so we can
+ * find out when the transfer is finished. For OUT endpoints, all descriptors
+ * therefore generate interrutps.
+ */
+static int gr_setup_out_desc_list(struct gr_ep *ep, struct gr_request *req,
+				  gfp_t gfp_flags)
+{
+	u16 bytes_left; /* Bytes left to provide descriptors for */
+	u16 bytes_used; /* Bytes accommodated for */
+	int ret = 0;
+
+	req->first_desc = NULL; /* Signals that no allocation is done yet */
+	bytes_left = req->req.length;
+	bytes_used = 0;
+	while (bytes_left > 0) {
+		dma_addr_t start = req->req.dma + bytes_used;
+		u16 size = min(bytes_left, ep->bytes_per_buffer);
+
+		/* Should not happen however - gr_queue stops such lengths */
+		if (size < ep->bytes_per_buffer)
+			dev_warn(ep->dev->dev,
+				 "Buffer overrun risk: %u < %u bytes/buffer\n",
+				 size, ep->bytes_per_buffer);
+
+		ret = gr_add_dma_desc(ep, req, start, size, gfp_flags);
+		if (ret)
+			goto alloc_err;
+
+		bytes_left -= size;
+		bytes_used += size;
+	}
+
+	req->first_desc->ctrl |= GR_DESC_OUT_CTRL_EN;
+
+	return 0;
+
+alloc_err:
+	gr_free_dma_desc_chain(ep->dev, req);
+
+	return ret;
+}
+
+/*
+ * Sets up a chain of struct gr_dma_descriptors pointing to buffers that
+ * together covers req->req.length bytes of the buffer at DMA address
+ * req->req.dma for the IN direction.
+ *
+ * When more data is provided than the maximum payload size, the hardware splits
+ * this up into several payloads automatically. Moreover, ep->bytes_per_buffer
+ * is always set to a multiple of the maximum payload (restricted to the valid
+ * number of maximum payloads during high bandwidth isochronous or interrupt
+ * transfers)
+ *
+ * All descriptors are enabled from the beginning and we only generate an
+ * interrupt for the last one indicating that the entire request has been pushed
+ * to hardware.
+ */
+static int gr_setup_in_desc_list(struct gr_ep *ep, struct gr_request *req,
+				 gfp_t gfp_flags)
+{
+	u16 bytes_left; /* Bytes left in req to provide descriptors for */
+	u16 bytes_used; /* Bytes in req accommodated for */
+	int ret = 0;
+
+	req->first_desc = NULL; /* Signals that no allocation is done yet */
+	bytes_left = req->req.length;
+	bytes_used = 0;
+	do { /* Allow for zero length packets */
+		dma_addr_t start = req->req.dma + bytes_used;
+		u16 size = min(bytes_left, ep->bytes_per_buffer);
+
+		ret = gr_add_dma_desc(ep, req, start, size, gfp_flags);
+		if (ret)
+			goto alloc_err;
+
+		bytes_left -= size;
+		bytes_used += size;
+	} while (bytes_left > 0);
+
+	/*
+	 * Send an extra zero length packet to indicate that no more data is
+	 * available when req->req.zero is set and the data length is even
+	 * multiples of ep->ep.maxpacket.
+	 */
+	if (req->req.zero && (req->req.length % ep->ep.maxpacket == 0)) {
+		ret = gr_add_dma_desc(ep, req, 0, 0, gfp_flags);
+		if (ret)
+			goto alloc_err;
+	}
+
+	/*
+	 * For IN packets we only want to know when the last packet has been
+	 * transmitted (not just put into internal buffers).
+	 */
+	req->last_desc->ctrl |= GR_DESC_IN_CTRL_PI;
+
+	return 0;
+
+alloc_err:
+	gr_free_dma_desc_chain(ep->dev, req);
+
+	return ret;
+}
+
+/* Must be called with dev->lock held */
+static int gr_queue(struct gr_ep *ep, struct gr_request *req, gfp_t gfp_flags)
+{
+	struct gr_udc *dev = ep->dev;
+	int ret;
+
+	if (unlikely(!ep->ep.desc && ep->num != 0)) {
+		dev_err(dev->dev, "No ep descriptor for %s\n", ep->ep.name);
+		return -EINVAL;
+	}
+
+	if (unlikely(!req->req.buf || !list_empty(&req->queue))) {
+		dev_err(dev->dev,
+			"Invalid request for %s: buf=%p list_empty=%d\n",
+			ep->ep.name, req->req.buf, list_empty(&req->queue));
+		return -EINVAL;
+	}
+
+	/*
+	 * The DMA controller can not handle smaller OUT buffers than
+	 * maxpacket. It could lead to buffer overruns if unexpectedly long
+	 * packet are received.
+	 */
+	if (!ep->is_in && (req->req.length % ep->ep.maxpacket) != 0) {
+		dev_err(dev->dev,
+			"OUT request length %d is not multiple of maxpacket\n",
+			req->req.length);
+		return -EMSGSIZE;
+	}
+
+	if (unlikely(!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN)) {
+		dev_err(dev->dev, "-ESHUTDOWN");
+		return -ESHUTDOWN;
+	}
+
+	/* Can't touch registers when suspended */
+	if (dev->ep0state == GR_EP0_SUSPEND) {
+		dev_err(dev->dev, "-EBUSY");
+		return -EBUSY;
+	}
+
+	/* Set up DMA mapping in case the caller didn't */
+	ret = usb_gadget_map_request(&dev->gadget, &req->req, ep->is_in);
+	if (ret) {
+		dev_err(dev->dev, "usb_gadget_map_request");
+		return ret;
+	}
+
+	if (ep->is_in)
+		ret = gr_setup_in_desc_list(ep, req, gfp_flags);
+	else
+		ret = gr_setup_out_desc_list(ep, req, gfp_flags);
+	if (ret)
+		return ret;
+
+	req->req.status = -EINPROGRESS;
+	req->req.actual = 0;
+	list_add_tail(&req->queue, &ep->queue);
+
+	/* Start DMA if not started, otherwise interrupt handler handles it */
+	if (!ep->dma_start && likely(!ep->stopped))
+		gr_start_dma(ep);
+
+	return 0;
+}
+
+/*
+ * Queue a request from within the driver.
+ *
+ * Must be called with dev->lock held.
+ */
+static inline int gr_queue_int(struct gr_ep *ep, struct gr_request *req,
+			       gfp_t gfp_flags)
+{
+	if (ep->is_in)
+		gr_dbgprint_request("RESP", ep, req);
+
+	return gr_queue(ep, req, gfp_flags);
+}
+
+/* ---------------------------------------------------------------------- */
+/* General helper functions */
+
+/*
+ * Dequeue ALL requests.
+ *
+ * Must be called with dev->lock held and irqs disabled.
+ */
+static void gr_ep_nuke(struct gr_ep *ep)
+{
+	struct gr_request *req;
+	struct gr_udc *dev;
+
+	dev = ep->dev;
+
+	ep->stopped = 1;
+	ep->dma_start = 0;
+	gr_abort_dma(ep);
+
+	while (!list_empty(&ep->queue)) {
+		req = list_first_entry(&ep->queue, struct gr_request, queue);
+		gr_finish_request(ep, req, -ESHUTDOWN);
+	}
+}
+
+/*
+ * Reset the hardware state of this endpoint.
+ *
+ * Must be called with dev->lock held.
+ */
+static void gr_ep_reset(struct gr_ep *ep)
+{
+	gr_write32(&ep->regs->epctrl, 0);
+	gr_write32(&ep->regs->dmactrl, 0);
+
+	ep->ep.maxpacket = MAX_CTRL_PL_SIZE;
+	ep->ep.desc = NULL;
+	ep->stopped = 1;
+	ep->dma_start = 0;
+}
+
+/*
+ * Generate STALL on ep0in/out.
+ *
+ * Must be called with dev->lock held.
+ */
+static void gr_control_stall(struct gr_udc *dev)
+{
+	u32 epctrl;
+
+	epctrl = gr_read32(&dev->epo[0].regs->epctrl);
+	gr_write32(&dev->epo[0].regs->epctrl, epctrl | GR_EPCTRL_CS);
+	epctrl = gr_read32(&dev->epi[0].regs->epctrl);
+	gr_write32(&dev->epi[0].regs->epctrl, epctrl | GR_EPCTRL_CS);
+
+	dev->ep0state = GR_EP0_STALL;
+}
+
+/*
+ * Halts, halts and wedges, or clears halt for an endpoint.
+ *
+ * Must be called with dev->lock held.
+ */
+static int gr_ep_halt_wedge(struct gr_ep *ep, int halt, int wedge, int fromhost)
+{
+	u32 epctrl;
+	int retval = 0;
+
+	if (ep->num && !ep->ep.desc)
+		return -EINVAL;
+
+	if (ep->num && ep->ep.desc->bmAttributes == USB_ENDPOINT_XFER_ISOC)
+		return -EOPNOTSUPP;
+
+	/* Never actually halt ep0, and therefore never clear halt for ep0 */
+	if (!ep->num) {
+		if (halt && !fromhost) {
+			/* ep0 halt from gadget - generate protocol stall */
+			gr_control_stall(ep->dev);
+			dev_dbg(ep->dev->dev, "EP: stall ep0\n");
+			return 0;
+		}
+		return -EINVAL;
+	}
+
+	dev_dbg(ep->dev->dev, "EP: %s halt %s\n",
+		(halt ? (wedge ? "wedge" : "set") : "clear"), ep->ep.name);
+
+	epctrl = gr_read32(&ep->regs->epctrl);
+	if (halt) {
+		/* Set HALT */
+		gr_write32(&ep->regs->epctrl, epctrl | GR_EPCTRL_EH);
+		ep->stopped = 1;
+		if (wedge)
+			ep->wedged = 1;
+	} else {
+		gr_write32(&ep->regs->epctrl, epctrl & ~GR_EPCTRL_EH);
+		ep->stopped = 0;
+		ep->wedged = 0;
+
+		/* Things might have been queued up in the meantime */
+		if (!ep->dma_start)
+			gr_start_dma(ep);
+	}
+
+	return retval;
+}
+
+/* Must be called with dev->lock held */
+static inline void gr_set_ep0state(struct gr_udc *dev, enum gr_ep0state value)
+{
+	if (dev->ep0state != value)
+		dev_vdbg(dev->dev, "STATE:  ep0state=%s\n",
+			 gr_ep0state_string(value));
+	dev->ep0state = value;
+}
+
+/*
+ * Should only be called when endpoints can not generate interrupts.
+ *
+ * Must be called with dev->lock held.
+ */
+static void gr_disable_interrupts_and_pullup(struct gr_udc *dev)
+{
+	gr_write32(&dev->regs->control, 0);
+	wmb(); /* Make sure that we do not deny one of our interrupts */
+	dev->irq_enabled = 0;
+}
+
+/*
+ * Stop all device activity and disable data line pullup.
+ *
+ * Must be called with dev->lock held and irqs disabled.
+ */
+static void gr_stop_activity(struct gr_udc *dev)
+{
+	struct gr_ep *ep;
+
+	list_for_each_entry(ep, &dev->ep_list, ep_list)
+		gr_ep_nuke(ep);
+
+	gr_disable_interrupts_and_pullup(dev);
+
+	gr_set_ep0state(dev, GR_EP0_DISCONNECT);
+	usb_gadget_set_state(&dev->gadget, USB_STATE_NOTATTACHED);
+}
+
+/* ---------------------------------------------------------------------- */
+/* ep0 setup packet handling */
+
+static void gr_ep0_testmode_complete(struct usb_ep *_ep,
+				     struct usb_request *_req)
+{
+	struct gr_ep *ep;
+	struct gr_udc *dev;
+	u32 control;
+
+	ep = container_of(_ep, struct gr_ep, ep);
+	dev = ep->dev;
+
+	spin_lock(&dev->lock);
+
+	control = gr_read32(&dev->regs->control);
+	control |= GR_CONTROL_TM | (dev->test_mode << GR_CONTROL_TS_POS);
+	gr_write32(&dev->regs->control, control);
+
+	spin_unlock(&dev->lock);
+}
+
+static void gr_ep0_dummy_complete(struct usb_ep *_ep, struct usb_request *_req)
+{
+	/* Nothing needs to be done here */
+}
+
+/*
+ * Queue a response on ep0in.
+ *
+ * Must be called with dev->lock held.
+ */
+static int gr_ep0_respond(struct gr_udc *dev, u8 *buf, int length,
+			  void (*complete)(struct usb_ep *ep,
+					   struct usb_request *req))
+{
+	u8 *reqbuf = dev->ep0reqi->req.buf;
+	int status;
+	int i;
+
+	for (i = 0; i < length; i++)
+		reqbuf[i] = buf[i];
+	dev->ep0reqi->req.length = length;
+	dev->ep0reqi->req.complete = complete;
+
+	status = gr_queue_int(&dev->epi[0], dev->ep0reqi, GFP_ATOMIC);
+	if (status < 0)
+		dev_err(dev->dev,
+			"Could not queue ep0in setup response: %d\n", status);
+
+	return status;
+}
+
+/*
+ * Queue a 2 byte response on ep0in.
+ *
+ * Must be called with dev->lock held.
+ */
+static inline int gr_ep0_respond_u16(struct gr_udc *dev, u16 response)
+{
+	__le16 le_response = cpu_to_le16(response);
+
+	return gr_ep0_respond(dev, (u8 *)&le_response, 2,
+			      gr_ep0_dummy_complete);
+}
+
+/*
+ * Queue a ZLP response on ep0in.
+ *
+ * Must be called with dev->lock held.
+ */
+static inline int gr_ep0_respond_empty(struct gr_udc *dev)
+{
+	return gr_ep0_respond(dev, NULL, 0, gr_ep0_dummy_complete);
+}
+
+/*
+ * This is run when a SET_ADDRESS request is received. First writes
+ * the new address to the control register which is updated internally
+ * when the next IN packet is ACKED.
+ *
+ * Must be called with dev->lock held.
+ */
+static void gr_set_address(struct gr_udc *dev, u8 address)
+{
+	u32 control;
+
+	control = gr_read32(&dev->regs->control) & ~GR_CONTROL_UA_MASK;
+	control |= (address << GR_CONTROL_UA_POS) & GR_CONTROL_UA_MASK;
+	control |= GR_CONTROL_SU;
+	gr_write32(&dev->regs->control, control);
+}
+
+/*
+ * Returns negative for STALL, 0 for successful handling and positive for
+ * delegation.
+ *
+ * Must be called with dev->lock held.
+ */
+static int gr_device_request(struct gr_udc *dev, u8 type, u8 request,
+			     u16 value, u16 index)
+{
+	u16 response;
+	u8 test;
+
+	switch (request) {
+	case USB_REQ_SET_ADDRESS:
+		dev_dbg(dev->dev, "STATUS: address %d\n", value & 0xff);
+		gr_set_address(dev, value & 0xff);
+		if (value)
+			usb_gadget_set_state(&dev->gadget, USB_STATE_ADDRESS);
+		else
+			usb_gadget_set_state(&dev->gadget, USB_STATE_DEFAULT);
+		return gr_ep0_respond_empty(dev);
+
+	case USB_REQ_GET_STATUS:
+		/* Self powered | remote wakeup */
+		response = 0x0001 | (dev->remote_wakeup ? 0x0002 : 0);
+		return gr_ep0_respond_u16(dev, response);
+
+	case USB_REQ_SET_FEATURE:
+		switch (value) {
+		case USB_DEVICE_REMOTE_WAKEUP:
+			/* Allow remote wakeup */
+			dev->remote_wakeup = 1;
+			return gr_ep0_respond_empty(dev);
+
+		case USB_DEVICE_TEST_MODE:
+			/* The hardware does not support TEST_FORCE_EN */
+			test = index >> 8;
+			if (test >= TEST_J && test <= TEST_PACKET) {
+				dev->test_mode = test;
+				return gr_ep0_respond(dev, NULL, 0,
+						      gr_ep0_testmode_complete);
+			}
+		}
+		break;
+
+	case USB_REQ_CLEAR_FEATURE:
+		switch (value) {
+		case USB_DEVICE_REMOTE_WAKEUP:
+			/* Disallow remote wakeup */
+			dev->remote_wakeup = 0;
+			return gr_ep0_respond_empty(dev);
+		}
+		break;
+	}
+
+	return 1; /* Delegate the rest */
+}
+
+/*
+ * Returns negative for STALL, 0 for successful handling and positive for
+ * delegation.
+ *
+ * Must be called with dev->lock held.
+ */
+static int gr_interface_request(struct gr_udc *dev, u8 type, u8 request,
+				u16 value, u16 index)
+{
+	if (dev->gadget.state != USB_STATE_CONFIGURED)
+		return -1;
+
+	/*
+	 * Should return STALL for invalid interfaces, but udc driver does not
+	 * know anything about that. However, many gadget drivers do not handle
+	 * GET_STATUS so we need to take care of that.
+	 */
+
+	switch (request) {
+	case USB_REQ_GET_STATUS:
+		return gr_ep0_respond_u16(dev, 0x0000);
+
+	case USB_REQ_SET_FEATURE:
+	case USB_REQ_CLEAR_FEATURE:
+		/*
+		 * No possible valid standard requests. Still let gadget drivers
+		 * have a go at it.
+		 */
+		break;
+	}
+
+	return 1; /* Delegate the rest */
+}
+
+/*
+ * Returns negative for STALL, 0 for successful handling and positive for
+ * delegation.
+ *
+ * Must be called with dev->lock held.
+ */
+static int gr_endpoint_request(struct gr_udc *dev, u8 type, u8 request,
+			       u16 value, u16 index)
+{
+	struct gr_ep *ep;
+	int status;
+	int halted;
+	u8 epnum = index & USB_ENDPOINT_NUMBER_MASK;
+	u8 is_in = index & USB_ENDPOINT_DIR_MASK;
+
+	if ((is_in && epnum >= dev->nepi) || (!is_in && epnum >= dev->nepo))
+		return -1;
+
+	if (dev->gadget.state != USB_STATE_CONFIGURED && epnum != 0)
+		return -1;
+
+	ep = (is_in ? &dev->epi[epnum] : &dev->epo[epnum]);
+
+	switch (request) {
+	case USB_REQ_GET_STATUS:
+		halted = gr_read32(&ep->regs->epctrl) & GR_EPCTRL_EH;
+		return gr_ep0_respond_u16(dev, halted ? 0x0001 : 0);
+
+	case USB_REQ_SET_FEATURE:
+		switch (value) {
+		case USB_ENDPOINT_HALT:
+			status = gr_ep_halt_wedge(ep, 1, 0, 1);
+			if (status >= 0)
+				status = gr_ep0_respond_empty(dev);
+			return status;
+		}
+		break;
+
+	case USB_REQ_CLEAR_FEATURE:
+		switch (value) {
+		case USB_ENDPOINT_HALT:
+			if (ep->wedged)
+				return -1;
+			status = gr_ep_halt_wedge(ep, 0, 0, 1);
+			if (status >= 0)
+				status = gr_ep0_respond_empty(dev);
+			return status;
+		}
+		break;
+	}
+
+	return 1; /* Delegate the rest */
+}
+
+/* Must be called with dev->lock held */
+static void gr_ep0out_requeue(struct gr_udc *dev)
+{
+	int ret = gr_queue_int(&dev->epo[0], dev->ep0reqo, GFP_ATOMIC);
+
+	if (ret)
+		dev_err(dev->dev, "Could not queue ep0out setup request: %d\n",
+			ret);
+}
+
+/*
+ * The main function dealing with setup requests on ep0.
+ *
+ * Must be called with dev->lock held and irqs disabled
+ */
+static void gr_ep0_setup(struct gr_udc *dev, struct gr_request *req)
+	__releases(&dev->lock)
+	__acquires(&dev->lock)
+{
+	union {
+		struct usb_ctrlrequest ctrl;
+		u8 raw[8];
+		u32 word[2];
+	} u;
+	u8 type;
+	u8 request;
+	u16 value;
+	u16 index;
+	u16 length;
+	int i;
+	int status;
+
+	/* Restore from ep0 halt */
+	if (dev->ep0state == GR_EP0_STALL) {
+		gr_set_ep0state(dev, GR_EP0_SETUP);
+		if (!req->req.actual)
+			goto out;
+	}
+
+	if (dev->ep0state == GR_EP0_ISTATUS) {
+		gr_set_ep0state(dev, GR_EP0_SETUP);
+		if (req->req.actual > 0)
+			dev_dbg(dev->dev,
+				"Unexpected setup packet at state %s\n",
+				gr_ep0state_string(GR_EP0_ISTATUS));
+		else
+			goto out; /* Got expected ZLP */
+	} else if (dev->ep0state != GR_EP0_SETUP) {
+		dev_info(dev->dev,
+			 "Unexpected ep0out request at state %s - stalling\n",
+			 gr_ep0state_string(dev->ep0state));
+		gr_control_stall(dev);
+		gr_set_ep0state(dev, GR_EP0_SETUP);
+		goto out;
+	} else if (!req->req.actual) {
+		dev_dbg(dev->dev, "Unexpected ZLP at state %s\n",
+			gr_ep0state_string(dev->ep0state));
+		goto out;
+	}
+
+	/* Handle SETUP packet */
+	for (i = 0; i < req->req.actual; i++)
+		u.raw[i] = ((u8 *)req->req.buf)[i];
+
+	type = u.ctrl.bRequestType;
+	request = u.ctrl.bRequest;
+	value = le16_to_cpu(u.ctrl.wValue);
+	index = le16_to_cpu(u.ctrl.wIndex);
+	length = le16_to_cpu(u.ctrl.wLength);
+
+	gr_dbgprint_devreq(dev, type, request, value, index, length);
+
+	/* Check for data stage */
+	if (length) {
+		if (type & USB_DIR_IN)
+			gr_set_ep0state(dev, GR_EP0_IDATA);
+		else
+			gr_set_ep0state(dev, GR_EP0_ODATA);
+	}
+
+	status = 1; /* Positive status flags delegation */
+	if ((type & USB_TYPE_MASK) == USB_TYPE_STANDARD) {
+		switch (type & USB_RECIP_MASK) {
+		case USB_RECIP_DEVICE:
+			status = gr_device_request(dev, type, request,
+						   value, index);
+			break;
+		case USB_RECIP_ENDPOINT:
+			status =  gr_endpoint_request(dev, type, request,
+						      value, index);
+			break;
+		case USB_RECIP_INTERFACE:
+			status = gr_interface_request(dev, type, request,
+						      value, index);
+			break;
+		}
+	}
+
+	if (status > 0) {
+		spin_unlock(&dev->lock);
+
+		dev_vdbg(dev->dev, "DELEGATE\n");
+		status = dev->driver->setup(&dev->gadget, &u.ctrl);
+
+		spin_lock(&dev->lock);
+	}
+
+	/* Generate STALL on both ep0out and ep0in if requested */
+	if (unlikely(status < 0)) {
+		dev_vdbg(dev->dev, "STALL\n");
+		gr_control_stall(dev);
+	}
+
+	if ((type & USB_TYPE_MASK) == USB_TYPE_STANDARD &&
+	    request == USB_REQ_SET_CONFIGURATION) {
+		if (!value) {
+			dev_dbg(dev->dev, "STATUS: deconfigured\n");
+			usb_gadget_set_state(&dev->gadget, USB_STATE_ADDRESS);
+		} else if (status >= 0) {
+			/* Not configured unless gadget OK:s it */
+			dev_dbg(dev->dev, "STATUS: configured: %d\n", value);
+			usb_gadget_set_state(&dev->gadget,
+					     USB_STATE_CONFIGURED);
+		}
+	}
+
+	/* Get ready for next stage */
+	if (dev->ep0state == GR_EP0_ODATA)
+		gr_set_ep0state(dev, GR_EP0_OSTATUS);
+	else if (dev->ep0state == GR_EP0_IDATA)
+		gr_set_ep0state(dev, GR_EP0_ISTATUS);
+	else
+		gr_set_ep0state(dev, GR_EP0_SETUP);
+
+out:
+	gr_ep0out_requeue(dev);
+}
+
+/* ---------------------------------------------------------------------- */
+/* VBUS and USB reset handling */
+
+/* Must be called with dev->lock held and irqs disabled  */
+static void gr_vbus_connected(struct gr_udc *dev, u32 status)
+{
+	u32 control;
+
+	dev->gadget.speed = GR_SPEED(status);
+	usb_gadget_set_state(&dev->gadget, USB_STATE_POWERED);
+
+	/* Turn on full interrupts and pullup */
+	control = (GR_CONTROL_SI | GR_CONTROL_UI | GR_CONTROL_VI |
+		   GR_CONTROL_SP | GR_CONTROL_EP);
+	gr_write32(&dev->regs->control, control);
+}
+
+/* Must be called with dev->lock held */
+static void gr_enable_vbus_detect(struct gr_udc *dev)
+{
+	u32 status;
+
+	dev->irq_enabled = 1;
+	wmb(); /* Make sure we do not ignore an interrupt */
+	gr_write32(&dev->regs->control, GR_CONTROL_VI);
+
+	/* Take care of the case we are already plugged in at this point */
+	status = gr_read32(&dev->regs->status);
+	if (status & GR_STATUS_VB)
+		gr_vbus_connected(dev, status);
+}
+
+/* Must be called with dev->lock held and irqs disabled */
+static void gr_vbus_disconnected(struct gr_udc *dev)
+{
+	gr_stop_activity(dev);
+
+	/* Report disconnect */
+	if (dev->driver && dev->driver->disconnect) {
+		spin_unlock(&dev->lock);
+
+		dev->driver->disconnect(&dev->gadget);
+
+		spin_lock(&dev->lock);
+	}
+
+	gr_enable_vbus_detect(dev);
+}
+
+/* Must be called with dev->lock held and irqs disabled */
+static void gr_udc_usbreset(struct gr_udc *dev, u32 status)
+{
+	gr_set_address(dev, 0);
+	gr_set_ep0state(dev, GR_EP0_SETUP);
+	usb_gadget_set_state(&dev->gadget, USB_STATE_DEFAULT);
+	dev->gadget.speed = GR_SPEED(status);
+
+	gr_ep_nuke(&dev->epo[0]);
+	gr_ep_nuke(&dev->epi[0]);
+	dev->epo[0].stopped = 0;
+	dev->epi[0].stopped = 0;
+	gr_ep0out_requeue(dev);
+}
+
+/* ---------------------------------------------------------------------- */
+/* Irq handling */
+
+/*
+ * Handles interrupts from in endpoints. Returns whether something was handled.
+ *
+ * Must be called with dev->lock held, irqs disabled and with !ep->stopped.
+ */
+static int gr_handle_in_ep(struct gr_ep *ep)
+{
+	struct gr_request *req;
+
+	req = list_first_entry(&ep->queue, struct gr_request, queue);
+	if (!req->last_desc)
+		return 0;
+
+	if (ACCESS_ONCE(req->last_desc->ctrl) & GR_DESC_IN_CTRL_EN)
+		return 0; /* Not put in hardware buffers yet */
+
+	if (gr_read32(&ep->regs->epstat) & (GR_EPSTAT_B1 | GR_EPSTAT_B0))
+		return 0; /* Not transmitted yet, still in hardware buffers */
+
+	/* Write complete */
+	gr_dma_advance(ep, 0);
+
+	return 1;
+}
+
+/*
+ * Handles interrupts from out endpoints. Returns whether something was handled.
+ *
+ * Must be called with dev->lock held, irqs disabled and with !ep->stopped.
+ */
+static int gr_handle_out_ep(struct gr_ep *ep)
+{
+	u32 ep_dmactrl;
+	u32 ctrl;
+	u16 len;
+	struct gr_request *req;
+	struct gr_udc *dev = ep->dev;
+
+	req = list_first_entry(&ep->queue, struct gr_request, queue);
+	if (!req->curr_desc)
+		return 0;
+
+	ctrl = ACCESS_ONCE(req->curr_desc->ctrl);
+	if (ctrl & GR_DESC_OUT_CTRL_EN)
+		return 0; /* Not received yet */
+
+	/* Read complete */
+	len = ctrl & GR_DESC_OUT_CTRL_LEN_MASK;
+	req->req.actual += len;
+	if (ctrl & GR_DESC_OUT_CTRL_SE)
+		req->setup = 1;
+
+	if (len < ep->ep.maxpacket || req->req.actual == req->req.length) {
+		/* Short packet or the expected size - we are done */
+
+		if ((ep == &dev->epo[0]) && (dev->ep0state == GR_EP0_OSTATUS)) {
+			/*
+			 * Send a status stage ZLP to ack the DATA stage in the
+			 * OUT direction. This needs to be done before
+			 * gr_dma_advance as that can lead to a call to
+			 * ep0_setup that can change dev->ep0state.
+			 */
+			gr_ep0_respond_empty(dev);
+			gr_set_ep0state(dev, GR_EP0_SETUP);
+		}
+
+		gr_dma_advance(ep, 0);
+	} else {
+		/* Not done yet. Enable the next descriptor to receive more. */
+		req->curr_desc = req->curr_desc->next_desc;
+		req->curr_desc->ctrl |= GR_DESC_OUT_CTRL_EN;
+
+		ep_dmactrl = gr_read32(&ep->regs->dmactrl);
+		gr_write32(&ep->regs->dmactrl, ep_dmactrl | GR_DMACTRL_DA);
+	}
+
+	return 1;
+}
+
+/*
+ * Handle state changes. Returns whether something was handled.
+ *
+ * Must be called with dev->lock held and irqs disabled.
+ */
+static int gr_handle_state_changes(struct gr_udc *dev)
+{
+	u32 status = gr_read32(&dev->regs->status);
+	int handled = 0;
+	int powstate = !(dev->gadget.state == USB_STATE_NOTATTACHED ||
+			 dev->gadget.state == USB_STATE_ATTACHED);
+
+	/* VBUS valid detected */
+	if (!powstate && (status & GR_STATUS_VB)) {
+		dev_dbg(dev->dev, "STATUS: vbus valid detected\n");
+		gr_vbus_connected(dev, status);
+		handled = 1;
+	}
+
+	/* Disconnect */
+	if (powstate && !(status & GR_STATUS_VB)) {
+		dev_dbg(dev->dev, "STATUS: vbus invalid detected\n");
+		gr_vbus_disconnected(dev);
+		handled = 1;
+	}
+
+	/* USB reset detected */
+	if (status & GR_STATUS_UR) {
+		dev_dbg(dev->dev, "STATUS: USB reset - speed is %s\n",
+			GR_SPEED_STR(status));
+		gr_write32(&dev->regs->status, GR_STATUS_UR);
+		gr_udc_usbreset(dev, status);
+		handled = 1;
+	}
+
+	/* Speed change */
+	if (dev->gadget.speed != GR_SPEED(status)) {
+		dev_dbg(dev->dev, "STATUS: USB Speed change to %s\n",
+			GR_SPEED_STR(status));
+		dev->gadget.speed = GR_SPEED(status);
+		handled = 1;
+	}
+
+	/* Going into suspend */
+	if ((dev->ep0state != GR_EP0_SUSPEND) && !(status & GR_STATUS_SU)) {
+		dev_dbg(dev->dev, "STATUS: USB suspend\n");
+		gr_set_ep0state(dev, GR_EP0_SUSPEND);
+		dev->suspended_from = dev->gadget.state;
+		usb_gadget_set_state(&dev->gadget, USB_STATE_SUSPENDED);
+
+		if ((dev->gadget.speed != USB_SPEED_UNKNOWN) &&
+		    dev->driver && dev->driver->suspend) {
+			spin_unlock(&dev->lock);
+
+			dev->driver->suspend(&dev->gadget);
+
+			spin_lock(&dev->lock);
+		}
+		handled = 1;
+	}
+
+	/* Coming out of suspend */
+	if ((dev->ep0state == GR_EP0_SUSPEND) && (status & GR_STATUS_SU)) {
+		dev_dbg(dev->dev, "STATUS: USB resume\n");
+		if (dev->suspended_from == USB_STATE_POWERED)
+			gr_set_ep0state(dev, GR_EP0_DISCONNECT);
+		else
+			gr_set_ep0state(dev, GR_EP0_SETUP);
+		usb_gadget_set_state(&dev->gadget, dev->suspended_from);
+
+		if ((dev->gadget.speed != USB_SPEED_UNKNOWN) &&
+		    dev->driver && dev->driver->resume) {
+			spin_unlock(&dev->lock);
+
+			dev->driver->resume(&dev->gadget);
+
+			spin_lock(&dev->lock);
+		}
+		handled = 1;
+	}
+
+	return handled;
+}
+
+/* Non-interrupt context irq handler */
+static irqreturn_t gr_irq_handler(int irq, void *_dev)
+{
+	struct gr_udc *dev = _dev;
+	struct gr_ep *ep;
+	int handled = 0;
+	int i;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	if (!dev->irq_enabled)
+		goto out;
+
+	/*
+	 * Check IN ep interrupts. We check these before the OUT eps because
+	 * some gadgets reuse the request that might already be currently
+	 * outstanding and needs to be completed (mainly setup requests).
+	 */
+	for (i = 0; i < dev->nepi; i++) {
+		ep = &dev->epi[i];
+		if (!ep->stopped && !ep->callback && !list_empty(&ep->queue))
+			handled = gr_handle_in_ep(ep) || handled;
+	}
+
+	/* Check OUT ep interrupts */
+	for (i = 0; i < dev->nepo; i++) {
+		ep = &dev->epo[i];
+		if (!ep->stopped && !ep->callback && !list_empty(&ep->queue))
+			handled = gr_handle_out_ep(ep) || handled;
+	}
+
+	/* Check status interrupts */
+	handled = gr_handle_state_changes(dev) || handled;
+
+	/*
+	 * Check AMBA DMA errors. Only check if we didn't find anything else to
+	 * handle because this shouldn't happen if we did everything right.
+	 */
+	if (!handled) {
+		list_for_each_entry(ep, &dev->ep_list, ep_list) {
+			if (gr_read32(&ep->regs->dmactrl) & GR_DMACTRL_AE) {
+				dev_err(dev->dev,
+					"AMBA Error occurred for %s\n",
+					ep->ep.name);
+				handled = 1;
+			}
+		}
+	}
+
+out:
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return handled ? IRQ_HANDLED : IRQ_NONE;
+}
+
+/* Interrupt context irq handler */
+static irqreturn_t gr_irq(int irq, void *_dev)
+{
+	struct gr_udc *dev = _dev;
+
+	if (!dev->irq_enabled)
+		return IRQ_NONE;
+
+	return IRQ_WAKE_THREAD;
+}
+
+/* ---------------------------------------------------------------------- */
+/* USB ep ops */
+
+/* Enable endpoint. Not for ep0in and ep0out that are handled separately. */
+static int gr_ep_enable(struct usb_ep *_ep,
+			const struct usb_endpoint_descriptor *desc)
+{
+	struct gr_udc *dev;
+	struct gr_ep *ep;
+	u8 mode;
+	u8 nt;
+	u16 max;
+	u16 buffer_size = 0;
+	u32 epctrl;
+
+	ep = container_of(_ep, struct gr_ep, ep);
+	if (!_ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT)
+		return -EINVAL;
+
+	dev = ep->dev;
+
+	/* 'ep0' IN and OUT are reserved */
+	if (ep == &dev->epo[0] || ep == &dev->epi[0])
+		return -EINVAL;
+
+	if (!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN)
+		return -ESHUTDOWN;
+
+	/* Make sure we are clear for enabling */
+	epctrl = gr_read32(&ep->regs->epctrl);
+	if (epctrl & GR_EPCTRL_EV)
+		return -EBUSY;
+
+	/* Check that directions match */
+	if (!ep->is_in != !usb_endpoint_dir_in(desc))
+		return -EINVAL;
+
+	/* Check ep num */
+	if ((!ep->is_in && ep->num >= dev->nepo) ||
+	    (ep->is_in && ep->num >= dev->nepi))
+		return -EINVAL;
+
+	if (usb_endpoint_xfer_control(desc)) {
+		mode = 0;
+	} else if (usb_endpoint_xfer_isoc(desc)) {
+		mode = 1;
+	} else if (usb_endpoint_xfer_bulk(desc)) {
+		mode = 2;
+	} else if (usb_endpoint_xfer_int(desc)) {
+		mode = 3;
+	} else {
+		dev_err(dev->dev, "Unknown transfer type for %s\n",
+			ep->ep.name);
+		return -EINVAL;
+	}
+
+	/*
+	 * Bits 10-0 set the max payload. 12-11 set the number of
+	 * additional transactions.
+	 */
+	max = 0x7ff & usb_endpoint_maxp(desc);
+	nt = 0x3 & (usb_endpoint_maxp(desc) >> 11);
+	buffer_size = GR_BUFFER_SIZE(epctrl);
+	if (nt && (mode == 0 || mode == 2)) {
+		dev_err(dev->dev,
+			"%s mode: multiple trans./microframe not valid\n",
+			(mode == 2 ? "Bulk" : "Control"));
+		return -EINVAL;
+	} else if (nt == 0x11) {
+		dev_err(dev->dev, "Invalid value for trans./microframe\n");
+		return -EINVAL;
+	} else if ((nt + 1) * max > buffer_size) {
+		dev_err(dev->dev, "Hw buffer size %d < max payload %d * %d\n",
+			buffer_size, (nt + 1), max);
+		return -EINVAL;
+	} else if (max == 0) {
+		dev_err(dev->dev, "Max payload cannot be set to 0\n");
+		return -EINVAL;
+	}
+
+	spin_lock(&ep->dev->lock);
+
+	if (!ep->stopped) {
+		spin_unlock(&ep->dev->lock);
+		return -EBUSY;
+	}
+
+	ep->stopped = 0;
+	ep->wedged = 0;
+	ep->ep.desc = desc;
+	ep->ep.maxpacket = max;
+	ep->dma_start = 0;
+
+
+	if (nt) {
+		/*
+		 * Maximum possible size of all payloads in one microframe
+		 * regardless of direction when using high-bandwidth mode.
+		 */
+		ep->bytes_per_buffer = (nt + 1) * max;
+	} else if (ep->is_in) {
+		/*
+		 * The biggest multiple of maximum packet size that fits into
+		 * the buffer. The hardware will split up into many packets in
+		 * the IN direction.
+		 */
+		ep->bytes_per_buffer = (buffer_size / max) * max;
+	} else {
+		/*
+		 * Only single packets will be placed the buffers in the OUT
+		 * direction.
+		 */
+		ep->bytes_per_buffer = max;
+	}
+
+	epctrl = (max << GR_EPCTRL_MAXPL_POS)
+		| (nt << GR_EPCTRL_NT_POS)
+		| (mode << GR_EPCTRL_TT_POS)
+		| GR_EPCTRL_EV;
+	if (ep->is_in)
+		epctrl |= GR_EPCTRL_PI;
+	gr_write32(&ep->regs->epctrl, epctrl);
+
+	gr_write32(&ep->regs->dmactrl, GR_DMACTRL_IE | GR_DMACTRL_AI);
+
+	spin_unlock(&ep->dev->lock);
+
+	dev_dbg(ep->dev->dev, "EP: %s enabled - %s with %d bytes/buffer\n",
+		ep->ep.name, gr_modestring[mode], ep->bytes_per_buffer);
+	return 0;
+}
+
+/* Disable endpoint. Not for ep0in and ep0out that are handled separately. */
+static int gr_ep_disable(struct usb_ep *_ep)
+{
+	struct gr_ep *ep;
+	struct gr_udc *dev;
+	unsigned long flags;
+
+	ep = container_of(_ep, struct gr_ep, ep);
+	if (!_ep || !ep->ep.desc)
+		return -ENODEV;
+
+	dev = ep->dev;
+
+	/* 'ep0' IN and OUT are reserved */
+	if (ep == &dev->epo[0] || ep == &dev->epi[0])
+		return -EINVAL;
+
+	if (dev->ep0state == GR_EP0_SUSPEND)
+		return -EBUSY;
+
+	dev_dbg(ep->dev->dev, "EP: disable %s\n", ep->ep.name);
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	gr_ep_nuke(ep);
+	gr_ep_reset(ep);
+	ep->ep.desc = NULL;
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return 0;
+}
+
+/*
+ * Frees a request, but not any DMA buffers associated with it
+ * (gr_finish_request should already have taken care of that).
+ */
+static void gr_free_request(struct usb_ep *_ep, struct usb_request *_req)
+{
+	struct gr_request *req;
+
+	if (!_ep || !_req)
+		return;
+	req = container_of(_req, struct gr_request, req);
+
+	/* Leads to memory leak */
+	WARN(!list_empty(&req->queue),
+	     "request not dequeued properly before freeing\n");
+
+	kfree(req);
+}
+
+/* Queue a request from the gadget */
+static int gr_queue_ext(struct usb_ep *_ep, struct usb_request *_req,
+			gfp_t gfp_flags)
+{
+	struct gr_ep *ep;
+	struct gr_request *req;
+	struct gr_udc *dev;
+	int ret;
+
+	if (unlikely(!_ep || !_req))
+		return -EINVAL;
+
+	ep = container_of(_ep, struct gr_ep, ep);
+	req = container_of(_req, struct gr_request, req);
+	dev = ep->dev;
+
+	spin_lock(&ep->dev->lock);
+
+	/*
+	 * The ep0 pointer in the gadget struct is used both for ep0in and
+	 * ep0out. In a data stage in the out direction ep0out needs to be used
+	 * instead of the default ep0in. Completion functions might use
+	 * driver_data, so that needs to be copied as well.
+	 */
+	if ((ep == &dev->epi[0]) && (dev->ep0state == GR_EP0_ODATA)) {
+		ep = &dev->epo[0];
+		ep->ep.driver_data = dev->epi[0].ep.driver_data;
+	}
+
+	if (ep->is_in)
+		gr_dbgprint_request("EXTERN", ep, req);
+
+	ret = gr_queue(ep, req, gfp_flags);
+
+	spin_unlock(&ep->dev->lock);
+
+	return ret;
+}
+
+/* Dequeue JUST ONE request */
+static int gr_dequeue(struct usb_ep *_ep, struct usb_request *_req)
+{
+	struct gr_request *req;
+	struct gr_ep *ep;
+	struct gr_udc *dev;
+	int ret = 0;
+	unsigned long flags;
+
+	ep = container_of(_ep, struct gr_ep, ep);
+	if (!_ep || !_req || (!ep->ep.desc && ep->num != 0))
+		return -EINVAL;
+	dev = ep->dev;
+	if (!dev->driver)
+		return -ESHUTDOWN;
+
+	/* We can't touch (DMA) registers when suspended */
+	if (dev->ep0state == GR_EP0_SUSPEND)
+		return -EBUSY;
+
+	spin_lock_irqsave(&dev->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) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (list_first_entry(&ep->queue, struct gr_request, queue) == req) {
+		/* This request is currently being processed */
+		gr_abort_dma(ep);
+		if (ep->stopped)
+			gr_finish_request(ep, req, -ECONNRESET);
+		else
+			gr_dma_advance(ep, -ECONNRESET);
+	} else if (!list_empty(&req->queue)) {
+		/* Not being processed - gr_finish_request dequeues it */
+		gr_finish_request(ep, req, -ECONNRESET);
+	} else {
+		ret = -EOPNOTSUPP;
+	}
+
+out:
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	return ret;
+}
+
+/* Helper for gr_set_halt and gr_set_wedge */
+static int gr_set_halt_wedge(struct usb_ep *_ep, int halt, int wedge)
+{
+	int ret;
+	struct gr_ep *ep;
+
+	if (!_ep)
+		return -ENODEV;
+	ep = container_of(_ep, struct gr_ep, ep);
+
+	spin_lock(&ep->dev->lock);
+
+	/* Halting an IN endpoint should fail if queue is not empty */
+	if (halt && ep->is_in && !list_empty(&ep->queue)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	ret = gr_ep_halt_wedge(ep, halt, wedge, 0);
+
+out:
+	spin_unlock(&ep->dev->lock);
+
+	return ret;
+}
+
+/* Halt endpoint */
+static int gr_set_halt(struct usb_ep *_ep, int halt)
+{
+	return gr_set_halt_wedge(_ep, halt, 0);
+}
+
+/* Halt and wedge endpoint */
+static int gr_set_wedge(struct usb_ep *_ep)
+{
+	return gr_set_halt_wedge(_ep, 1, 1);
+}
+
+/*
+ * Return the total number of bytes currently stored in the internal buffers of
+ * the endpoint.
+ */
+static int gr_fifo_status(struct usb_ep *_ep)
+{
+	struct gr_ep *ep;
+	u32 epstat;
+	u32 bytes = 0;
+
+	if (!_ep)
+		return -ENODEV;
+	ep = container_of(_ep, struct gr_ep, ep);
+
+	epstat = gr_read32(&ep->regs->epstat);
+
+	if (epstat & GR_EPSTAT_B0)
+		bytes += (epstat & GR_EPSTAT_B0CNT_MASK) >> GR_EPSTAT_B0CNT_POS;
+	if (epstat & GR_EPSTAT_B1)
+		bytes += (epstat & GR_EPSTAT_B1CNT_MASK) >> GR_EPSTAT_B1CNT_POS;
+
+	return bytes;
+}
+
+
+/* Empty data from internal buffers of an endpoint. */
+static void gr_fifo_flush(struct usb_ep *_ep)
+{
+	struct gr_ep *ep;
+	u32 epctrl;
+
+	if (!_ep)
+		return;
+	ep = container_of(_ep, struct gr_ep, ep);
+	dev_vdbg(ep->dev->dev, "EP: flush fifo %s\n", ep->ep.name);
+
+	spin_lock(&ep->dev->lock);
+
+	epctrl = gr_read32(&ep->regs->epctrl);
+	epctrl |= GR_EPCTRL_CB;
+	gr_write32(&ep->regs->epctrl, epctrl);
+
+	spin_unlock(&ep->dev->lock);
+}
+
+static struct usb_ep_ops gr_ep_ops = {
+	.enable		= gr_ep_enable,
+	.disable	= gr_ep_disable,
+
+	.alloc_request	= gr_alloc_request,
+	.free_request	= gr_free_request,
+
+	.queue		= gr_queue_ext,
+	.dequeue	= gr_dequeue,
+
+	.set_halt	= gr_set_halt,
+	.set_wedge	= gr_set_wedge,
+	.fifo_status	= gr_fifo_status,
+	.fifo_flush	= gr_fifo_flush,
+};
+
+/* ---------------------------------------------------------------------- */
+/* USB Gadget ops */
+
+static int gr_get_frame(struct usb_gadget *_gadget)
+{
+	struct gr_udc *dev;
+
+	if (!_gadget)
+		return -ENODEV;
+	dev = container_of(_gadget, struct gr_udc, gadget);
+	return gr_read32(&dev->regs->status) & GR_STATUS_FN_MASK;
+}
+
+static int gr_wakeup(struct usb_gadget *_gadget)
+{
+	struct gr_udc *dev;
+
+	if (!_gadget)
+		return -ENODEV;
+	dev = container_of(_gadget, struct gr_udc, gadget);
+
+	/* Remote wakeup feature not enabled by host*/
+	if (!dev->remote_wakeup)
+		return -EINVAL;
+
+	spin_lock(&dev->lock);
+
+	gr_write32(&dev->regs->control,
+		   gr_read32(&dev->regs->control) | GR_CONTROL_RW);
+
+	spin_unlock(&dev->lock);
+
+	return 0;
+}
+
+static int gr_pullup(struct usb_gadget *_gadget, int is_on)
+{
+	struct gr_udc *dev;
+	u32 control;
+
+	if (!_gadget)
+		return -ENODEV;
+	dev = container_of(_gadget, struct gr_udc, gadget);
+
+	spin_lock(&dev->lock);
+
+	control = gr_read32(&dev->regs->control);
+	if (is_on)
+		control |= GR_CONTROL_EP;
+	else
+		control &= ~GR_CONTROL_EP;
+	gr_write32(&dev->regs->control, control);
+
+	spin_unlock(&dev->lock);
+
+	return 0;
+}
+
+static int gr_udc_start(struct usb_gadget *gadget,
+			struct usb_gadget_driver *driver)
+{
+	struct gr_udc *dev = to_gr_udc(gadget);
+
+	spin_lock(&dev->lock);
+
+	/* Hook up the driver */
+	driver->driver.bus = NULL;
+	dev->driver = driver;
+
+	/* Get ready for host detection */
+	gr_enable_vbus_detect(dev);
+
+	spin_unlock(&dev->lock);
+
+	dev_info(dev->dev, "Started with gadget driver '%s'\n",
+		 driver->driver.name);
+
+	return 0;
+}
+
+static int gr_udc_stop(struct usb_gadget *gadget,
+		       struct usb_gadget_driver *driver)
+{
+	struct gr_udc *dev = to_gr_udc(gadget);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->lock, flags);
+
+	dev->driver = NULL;
+	gr_stop_activity(dev);
+
+	spin_unlock_irqrestore(&dev->lock, flags);
+
+	dev_info(dev->dev, "Stopped\n");
+
+	return 0;
+}
+
+static const struct usb_gadget_ops gr_ops = {
+	.get_frame	= gr_get_frame,
+	.wakeup         = gr_wakeup,
+	.pullup         = gr_pullup,
+	.udc_start	= gr_udc_start,
+	.udc_stop	= gr_udc_stop,
+	/* Other operations not supported */
+};
+
+/* ---------------------------------------------------------------------- */
+/* Module probe, removal and of-matching */
+
+static const char * const onames[] = {
+	"ep0out", "ep1out", "ep2out", "ep3out", "ep4out", "ep5out",
+	"ep6out", "ep7out", "ep8out", "ep9out", "ep10out", "ep11out",
+	"ep12out", "ep13out", "ep14out", "ep15out"
+};
+
+static const char * const inames[] = {
+	"ep0in", "ep1in", "ep2in", "ep3in", "ep4in", "ep5in",
+	"ep6in", "ep7in", "ep8in", "ep9in", "ep10in", "ep11in",
+	"ep12in", "ep13in", "ep14in", "ep15in"
+};
+
+/* Must be called with dev->lock held */
+static int gr_ep_init(struct gr_udc *dev, int num, int is_in, u32 maxplimit)
+{
+	struct gr_ep *ep;
+	struct gr_request *req;
+	struct usb_request *_req;
+	void *buf;
+
+	if (is_in) {
+		ep = &dev->epi[num];
+		ep->ep.name = inames[num];
+		ep->regs = &dev->regs->epi[num];
+	} else {
+		ep = &dev->epo[num];
+		ep->ep.name = onames[num];
+		ep->regs = &dev->regs->epo[num];
+	}
+
+	gr_ep_reset(ep);
+	ep->num = num;
+	ep->is_in = is_in;
+	ep->dev = dev;
+	ep->ep.ops = &gr_ep_ops;
+	INIT_LIST_HEAD(&ep->queue);
+
+	if (num == 0) {
+		_req = gr_alloc_request(&ep->ep, GFP_KERNEL);
+		buf = devm_kzalloc(dev->dev, PAGE_SIZE, GFP_DMA | GFP_KERNEL);
+		if (!_req || !buf) {
+			/* possible _req freed by gr_probe via gr_remove */
+			return -ENOMEM;
+		}
+
+		req = container_of(_req, struct gr_request, req);
+		req->req.buf = buf;
+		req->req.length = MAX_CTRL_PL_SIZE;
+
+		if (is_in)
+			dev->ep0reqi = req; /* Complete gets set as used */
+		else
+			dev->ep0reqo = req; /* Completion treated separately */
+
+		usb_ep_set_maxpacket_limit(&ep->ep, MAX_CTRL_PL_SIZE);
+		ep->bytes_per_buffer = MAX_CTRL_PL_SIZE;
+	} else {
+		usb_ep_set_maxpacket_limit(&ep->ep, (u16)maxplimit);
+		list_add_tail(&ep->ep.ep_list, &dev->gadget.ep_list);
+	}
+	list_add_tail(&ep->ep_list, &dev->ep_list);
+
+	return 0;
+}
+
+/* Must be called with dev->lock held */
+static int gr_udc_init(struct gr_udc *dev)
+{
+	struct device_node *np = dev->dev->of_node;
+	u32 epctrl_val;
+	u32 dmactrl_val;
+	int i;
+	int ret = 0;
+	u32 *bufsizes;
+	u32 bufsize;
+	int len;
+
+	gr_set_address(dev, 0);
+
+	INIT_LIST_HEAD(&dev->gadget.ep_list);
+	dev->gadget.speed = USB_SPEED_UNKNOWN;
+	dev->gadget.ep0 = &dev->epi[0].ep;
+
+	INIT_LIST_HEAD(&dev->ep_list);
+	gr_set_ep0state(dev, GR_EP0_DISCONNECT);
+
+	bufsizes = (u32 *)of_get_property(np, "epobufsizes", &len);
+	len /= sizeof(u32);
+	for (i = 0; i < dev->nepo; i++) {
+		bufsize = (bufsizes && i < len) ? bufsizes[i] : 1024;
+		ret = gr_ep_init(dev, i, 0, bufsize);
+		if (ret)
+			return ret;
+	}
+
+	bufsizes = (u32 *)of_get_property(np, "epibufsizes", &len);
+	len /= sizeof(u32);
+	for (i = 0; i < dev->nepi; i++) {
+		bufsize = (bufsizes && i < len) ? bufsizes[i] : 1024;
+		ret = gr_ep_init(dev, i, 1, bufsize);
+		if (ret)
+			return ret;
+	}
+
+	/* Must be disabled by default */
+	dev->remote_wakeup = 0;
+
+	/* Enable ep0out and ep0in */
+	epctrl_val = (MAX_CTRL_PL_SIZE << GR_EPCTRL_MAXPL_POS) | GR_EPCTRL_EV;
+	dmactrl_val = GR_DMACTRL_IE | GR_DMACTRL_AI;
+	gr_write32(&dev->epo[0].regs->epctrl, epctrl_val);
+	gr_write32(&dev->epi[0].regs->epctrl, epctrl_val | GR_EPCTRL_PI);
+	gr_write32(&dev->epo[0].regs->dmactrl, dmactrl_val);
+	gr_write32(&dev->epi[0].regs->dmactrl, dmactrl_val);
+
+	return 0;
+}
+
+static int gr_remove(struct platform_device *ofdev)
+{
+	struct gr_udc *dev = dev_get_drvdata(&ofdev->dev);
+
+	if (dev->added)
+		usb_del_gadget_udc(&dev->gadget); /* Shuts everything down */
+	if (dev->driver)
+		return -EBUSY;
+
+	gr_dfs_delete(dev);
+	if (dev->desc_pool)
+		dma_pool_destroy(dev->desc_pool);
+	dev_set_drvdata(&ofdev->dev, NULL);
+
+	gr_free_request(&dev->epi[0].ep, &dev->ep0reqi->req);
+	gr_free_request(&dev->epo[0].ep, &dev->ep0reqo->req);
+
+	return 0;
+}
+static int gr_request_irq(struct gr_udc *dev, int irq)
+{
+	return devm_request_threaded_irq(dev->dev, irq, gr_irq, gr_irq_handler,
+					 IRQF_SHARED, driver_name, dev);
+}
+
+static int gr_probe(struct platform_device *ofdev)
+{
+	struct gr_udc *dev;
+	struct resource *res;
+	struct gr_regs __iomem *regs;
+	int retval;
+	u32 status;
+
+	dev = devm_kzalloc(&ofdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+	dev->dev = &ofdev->dev;
+
+	res = platform_get_resource(ofdev, IORESOURCE_MEM, 0);
+	regs = devm_ioremap_resource(dev->dev, res);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	dev->irq = irq_of_parse_and_map(dev->dev->of_node, 0);
+	if (!dev->irq) {
+		dev_err(dev->dev, "No irq found\n");
+		return -ENODEV;
+	}
+
+	/* Some core configurations has separate irqs for IN and OUT events */
+	dev->irqi = irq_of_parse_and_map(dev->dev->of_node, 1);
+	if (dev->irqi) {
+		dev->irqo = irq_of_parse_and_map(dev->dev->of_node, 2);
+		if (!dev->irqo) {
+			dev_err(dev->dev, "Found irqi but not irqo\n");
+			return -ENODEV;
+		}
+	}
+
+	dev->gadget.name = driver_name;
+	dev->gadget.max_speed = USB_SPEED_HIGH;
+	dev->gadget.ops = &gr_ops;
+	dev->gadget.quirk_ep_out_aligned_size = true;
+
+	spin_lock_init(&dev->lock);
+	dev->regs = regs;
+
+	dev_set_drvdata(&ofdev->dev, dev);
+
+	/* Determine number of endpoints and data interface mode */
+	status = gr_read32(&dev->regs->status);
+	dev->nepi = ((status & GR_STATUS_NEPI_MASK) >> GR_STATUS_NEPI_POS) + 1;
+	dev->nepo = ((status & GR_STATUS_NEPO_MASK) >> GR_STATUS_NEPO_POS) + 1;
+
+	if (!(status & GR_STATUS_DM)) {
+		dev_err(dev->dev, "Slave mode cores are not supported\n");
+		return -ENODEV;
+	}
+
+	/* --- Effects of the following calls might need explicit cleanup --- */
+
+	/* Create DMA pool for descriptors */
+	dev->desc_pool = dma_pool_create("desc_pool", dev->dev,
+					 sizeof(struct gr_dma_desc), 4, 0);
+	if (!dev->desc_pool) {
+		dev_err(dev->dev, "Could not allocate DMA pool");
+		return -ENOMEM;
+	}
+
+	spin_lock(&dev->lock);
+
+	/* Inside lock so that no gadget can use this udc until probe is done */
+	retval = usb_add_gadget_udc(dev->dev, &dev->gadget);
+	if (retval) {
+		dev_err(dev->dev, "Could not add gadget udc");
+		goto out;
+	}
+	dev->added = 1;
+
+	retval = gr_udc_init(dev);
+	if (retval)
+		goto out;
+
+	gr_dfs_create(dev);
+
+	/* Clear all interrupt enables that might be left on since last boot */
+	gr_disable_interrupts_and_pullup(dev);
+
+	retval = gr_request_irq(dev, dev->irq);
+	if (retval) {
+		dev_err(dev->dev, "Failed to request irq %d\n", dev->irq);
+		goto out;
+	}
+
+	if (dev->irqi) {
+		retval = gr_request_irq(dev, dev->irqi);
+		if (retval) {
+			dev_err(dev->dev, "Failed to request irqi %d\n",
+				dev->irqi);
+			goto out;
+		}
+		retval = gr_request_irq(dev, dev->irqo);
+		if (retval) {
+			dev_err(dev->dev, "Failed to request irqo %d\n",
+				dev->irqo);
+			goto out;
+		}
+	}
+
+	if (dev->irqi)
+		dev_info(dev->dev, "regs: %p, irqs %d, %d, %d\n", dev->regs,
+			 dev->irq, dev->irqi, dev->irqo);
+	else
+		dev_info(dev->dev, "regs: %p, irq %d\n", dev->regs, dev->irq);
+
+out:
+	spin_unlock(&dev->lock);
+
+	if (retval)
+		gr_remove(ofdev);
+
+	return retval;
+}
+
+static struct of_device_id gr_match[] = {
+	{.name = "GAISLER_USBDC"},
+	{.name = "01_021"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, gr_match);
+
+static struct platform_driver gr_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = gr_match,
+	},
+	.probe = gr_probe,
+	.remove = gr_remove,
+};
+module_platform_driver(gr_driver);
+
+MODULE_AUTHOR("Aeroflex Gaisler AB.");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/gadget/gr_udc.h b/drivers/usb/gadget/gr_udc.h
new file mode 100644
index 000000000000..8388897d9ec3
--- /dev/null
+++ b/drivers/usb/gadget/gr_udc.h
@@ -0,0 +1,220 @@
+/*
+ * USB Peripheral Controller driver for Aeroflex Gaisler GRUSBDC.
+ *
+ * 2013 (c) Aeroflex Gaisler AB
+ *
+ * This driver supports GRUSBDC USB Device Controller cores available in the
+ * GRLIB VHDL IP core library.
+ *
+ * Full documentation of the GRUSBDC core can be found here:
+ * http://www.gaisler.com/products/grlib/grip.pdf
+ *
+ * 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.
+ *
+ * Contributors:
+ * - Andreas Larsson <andreas@gaisler.com>
+ * - Marko Isomaki
+ */
+
+/* Control registers on the AMBA bus */
+
+#define GR_MAXEP	16	/* Max # endpoints for *each* direction */
+
+struct gr_epregs {
+	u32 epctrl;
+	union {
+		struct { /* Slave mode*/
+			u32 slvctrl;
+			u32 slvdata;
+		};
+		struct { /* DMA mode*/
+			u32 dmactrl;
+			u32 dmaaddr;
+		};
+	};
+	u32 epstat;
+};
+
+struct gr_regs {
+	struct gr_epregs	epo[GR_MAXEP];	/* 0x000 - 0x0fc */
+	struct gr_epregs	epi[GR_MAXEP];	/* 0x100 - 0x1fc */
+	u32			control;	/* 0x200 */
+	u32			status;		/* 0x204 */
+};
+
+#define GR_EPCTRL_BUFSZ_SCALER	8
+#define GR_EPCTRL_BUFSZ_MASK	0xffe00000
+#define GR_EPCTRL_BUFSZ_POS	21
+#define GR_EPCTRL_PI		BIT(20)
+#define GR_EPCTRL_CB		BIT(19)
+#define GR_EPCTRL_CS		BIT(18)
+#define GR_EPCTRL_MAXPL_MASK	0x0003ff80
+#define GR_EPCTRL_MAXPL_POS	7
+#define GR_EPCTRL_NT_MASK	0x00000060
+#define GR_EPCTRL_NT_POS	5
+#define GR_EPCTRL_TT_MASK	0x00000018
+#define GR_EPCTRL_TT_POS	3
+#define GR_EPCTRL_EH		BIT(2)
+#define GR_EPCTRL_ED		BIT(1)
+#define GR_EPCTRL_EV		BIT(0)
+
+#define GR_DMACTRL_AE		BIT(10)
+#define GR_DMACTRL_AD		BIT(3)
+#define GR_DMACTRL_AI		BIT(2)
+#define GR_DMACTRL_IE		BIT(1)
+#define GR_DMACTRL_DA		BIT(0)
+
+#define GR_EPSTAT_PT		BIT(29)
+#define GR_EPSTAT_PR		BIT(29)
+#define GR_EPSTAT_B1CNT_MASK	0x1fff0000
+#define GR_EPSTAT_B1CNT_POS	16
+#define GR_EPSTAT_B0CNT_MASK	0x0000fff8
+#define GR_EPSTAT_B0CNT_POS	3
+#define GR_EPSTAT_B1		BIT(2)
+#define GR_EPSTAT_B0		BIT(1)
+#define GR_EPSTAT_BS		BIT(0)
+
+#define GR_CONTROL_SI		BIT(31)
+#define GR_CONTROL_UI		BIT(30)
+#define GR_CONTROL_VI		BIT(29)
+#define GR_CONTROL_SP		BIT(28)
+#define GR_CONTROL_FI		BIT(27)
+#define GR_CONTROL_EP		BIT(14)
+#define GR_CONTROL_DH		BIT(13)
+#define GR_CONTROL_RW		BIT(12)
+#define GR_CONTROL_TS_MASK	0x00000e00
+#define GR_CONTROL_TS_POS	9
+#define GR_CONTROL_TM		BIT(8)
+#define GR_CONTROL_UA_MASK	0x000000fe
+#define GR_CONTROL_UA_POS	1
+#define GR_CONTROL_SU		BIT(0)
+
+#define GR_STATUS_NEPI_MASK	0xf0000000
+#define GR_STATUS_NEPI_POS	28
+#define GR_STATUS_NEPO_MASK	0x0f000000
+#define GR_STATUS_NEPO_POS	24
+#define GR_STATUS_DM		BIT(23)
+#define GR_STATUS_SU		BIT(17)
+#define GR_STATUS_UR		BIT(16)
+#define GR_STATUS_VB		BIT(15)
+#define GR_STATUS_SP		BIT(14)
+#define GR_STATUS_AF_MASK	0x00003800
+#define GR_STATUS_AF_POS	11
+#define GR_STATUS_FN_MASK	0x000007ff
+#define GR_STATUS_FN_POS	0
+
+
+#define MAX_CTRL_PL_SIZE 64 /* As per USB standard for full and high speed */
+
+/*-------------------------------------------------------------------------*/
+
+/* Driver data structures and utilities */
+
+struct gr_dma_desc {
+	u32 ctrl;
+	u32 data;
+	u32 next;
+
+	/* These must be last because hw uses the previous three */
+	u32 paddr;
+	struct gr_dma_desc *next_desc;
+};
+
+#define GR_DESC_OUT_CTRL_SE		BIT(17)
+#define GR_DESC_OUT_CTRL_IE		BIT(15)
+#define GR_DESC_OUT_CTRL_NX		BIT(14)
+#define GR_DESC_OUT_CTRL_EN		BIT(13)
+#define GR_DESC_OUT_CTRL_LEN_MASK	0x00001fff
+
+#define GR_DESC_IN_CTRL_MO		BIT(18)
+#define GR_DESC_IN_CTRL_PI		BIT(17)
+#define GR_DESC_IN_CTRL_ML		BIT(16)
+#define GR_DESC_IN_CTRL_IE		BIT(15)
+#define GR_DESC_IN_CTRL_NX		BIT(14)
+#define GR_DESC_IN_CTRL_EN		BIT(13)
+#define GR_DESC_IN_CTRL_LEN_MASK	0x00001fff
+
+#define GR_DESC_DMAADDR_MASK		0xfffffffc
+
+struct gr_ep {
+	struct usb_ep ep;
+	struct gr_udc *dev;
+	u16 bytes_per_buffer;
+	unsigned int dma_start;
+	struct gr_epregs __iomem *regs;
+
+	unsigned num:8;
+	unsigned is_in:1;
+	unsigned stopped:1;
+	unsigned wedged:1;
+	unsigned callback:1;
+
+	/* analogous to a host-side qh */
+	struct list_head queue;
+
+	struct list_head ep_list;
+};
+
+struct gr_request {
+	struct usb_request req;
+	struct list_head queue;
+
+	/* Chain of dma descriptors */
+	struct gr_dma_desc *first_desc; /* First in the chain */
+	struct gr_dma_desc *curr_desc; /* Current descriptor */
+	struct gr_dma_desc *last_desc; /* Last in the chain */
+
+	u8 setup; /* Setup packet */
+};
+
+enum gr_ep0state {
+	GR_EP0_DISCONNECT = 0,	/* No host */
+	GR_EP0_SETUP,		/* Between STATUS ack and SETUP report */
+	GR_EP0_IDATA,		/* IN data stage */
+	GR_EP0_ODATA,		/* OUT data stage */
+	GR_EP0_ISTATUS,		/* Status stage after IN data stage */
+	GR_EP0_OSTATUS,		/* Status stage after OUT data stage */
+	GR_EP0_STALL,		/* Data or status stages */
+	GR_EP0_SUSPEND,		/* USB suspend */
+};
+
+struct gr_udc {
+	struct usb_gadget gadget;
+	struct gr_ep epi[GR_MAXEP];
+	struct gr_ep epo[GR_MAXEP];
+	struct usb_gadget_driver *driver;
+	struct dma_pool *desc_pool;
+	struct device *dev;
+
+	enum gr_ep0state ep0state;
+	struct gr_request *ep0reqo;
+	struct gr_request *ep0reqi;
+
+	struct gr_regs __iomem *regs;
+	int irq;
+	int irqi;
+	int irqo;
+
+	unsigned added:1;
+	unsigned irq_enabled:1;
+	unsigned remote_wakeup:1;
+
+	u8 test_mode;
+
+	enum usb_device_state suspended_from;
+
+	unsigned int nepi;
+	unsigned int nepo;
+
+	struct list_head ep_list;
+
+	spinlock_t lock; /* General lock, a.k.a. "dev->lock" in comments */
+
+	struct dentry *dfs_root;
+	struct dentry *dfs_state;
+};
+
+#define to_gr_udc(gadget)	(container_of((gadget), struct gr_udc, gadget))