musb-new: port of Linux musb driver

Existing U-Boot musb driver has no support for the new gadget framework
and also seems to have other limitations. As gadget framework is ported
from Linux it seems pretty natural to port musb gadget driver as well.

This driver supports both host and peripheral modes.

This is not a replacement for current musb driver (at least now) as
there are still some consumers of the old UDC interface.

No DMA operation support included, CONFIG_MUSB_PIO_ONLY should be
defined.

Virtual root hub device is not implemented.

Known problems: with no devices connected usb_lowlevel_start() fails.

Signed-off-by: Ilya Yanok <ilya.yanok@cogentembedded.com>

1 files changed, 1089 insertions, 0 deletions

diff --git a/drivers/usb/musb-new/musb_gadget_ep0.c b/drivers/usb/musb-new/musb_gadget_ep0.c
new file mode 100644
index 0000000000..6599d386dc
--- /dev/null
+++ b/drivers/usb/musb-new/musb_gadget_ep0.c
@@ -0,0 +1,1089 @@
+/*
+ * MUSB OTG peripheral driver ep0 handling
+ *
+ * Copyright 2005 Mentor Graphics Corporation
+ * Copyright (C) 2005-2006 by Texas Instruments
+ * Copyright (C) 2006-2007 Nokia Corporation
+ * Copyright (C) 2008-2009 MontaVista Software, Inc. <source@mvista.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#define __UBOOT__
+#ifndef __UBOOT__
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/timer.h>
+#include <linux/spinlock.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#else
+#include <common.h>
+#include "linux-compat.h"
+#endif
+
+#include "musb_core.h"
+
+/* ep0 is always musb->endpoints[0].ep_in */
+#define	next_ep0_request(musb)	next_in_request(&(musb)->endpoints[0])
+
+/*
+ * locking note:  we use only the controller lock, for simpler correctness.
+ * It's always held with IRQs blocked.
+ *
+ * It protects the ep0 request queue as well as ep0_state, not just the
+ * controller and indexed registers.  And that lock stays held unless it
+ * needs to be dropped to allow reentering this driver ... like upcalls to
+ * the gadget driver, or adjusting endpoint halt status.
+ */
+
+static char *decode_ep0stage(u8 stage)
+{
+	switch (stage) {
+	case MUSB_EP0_STAGE_IDLE:	return "idle";
+	case MUSB_EP0_STAGE_SETUP:	return "setup";
+	case MUSB_EP0_STAGE_TX:		return "in";
+	case MUSB_EP0_STAGE_RX:		return "out";
+	case MUSB_EP0_STAGE_ACKWAIT:	return "wait";
+	case MUSB_EP0_STAGE_STATUSIN:	return "in/status";
+	case MUSB_EP0_STAGE_STATUSOUT:	return "out/status";
+	default:			return "?";
+	}
+}
+
+/* handle a standard GET_STATUS request
+ * Context:  caller holds controller lock
+ */
+static int service_tx_status_request(
+	struct musb *musb,
+	const struct usb_ctrlrequest *ctrlrequest)
+{
+	void __iomem	*mbase = musb->mregs;
+	int handled = 1;
+	u8 result[2], epnum = 0;
+	const u8 recip = ctrlrequest->bRequestType & USB_RECIP_MASK;
+
+	result[1] = 0;
+
+	switch (recip) {
+	case USB_RECIP_DEVICE:
+		result[0] = musb->is_self_powered << USB_DEVICE_SELF_POWERED;
+		result[0] |= musb->may_wakeup << USB_DEVICE_REMOTE_WAKEUP;
+		if (musb->g.is_otg) {
+			result[0] |= musb->g.b_hnp_enable
+				<< USB_DEVICE_B_HNP_ENABLE;
+			result[0] |= musb->g.a_alt_hnp_support
+				<< USB_DEVICE_A_ALT_HNP_SUPPORT;
+			result[0] |= musb->g.a_hnp_support
+				<< USB_DEVICE_A_HNP_SUPPORT;
+		}
+		break;
+
+	case USB_RECIP_INTERFACE:
+		result[0] = 0;
+		break;
+
+	case USB_RECIP_ENDPOINT: {
+		int		is_in;
+		struct musb_ep	*ep;
+		u16		tmp;
+		void __iomem	*regs;
+
+		epnum = (u8) ctrlrequest->wIndex;
+		if (!epnum) {
+			result[0] = 0;
+			break;
+		}
+
+		is_in = epnum & USB_DIR_IN;
+		if (is_in) {
+			epnum &= 0x0f;
+			ep = &musb->endpoints[epnum].ep_in;
+		} else {
+			ep = &musb->endpoints[epnum].ep_out;
+		}
+		regs = musb->endpoints[epnum].regs;
+
+		if (epnum >= MUSB_C_NUM_EPS || !ep->desc) {
+			handled = -EINVAL;
+			break;
+		}
+
+		musb_ep_select(mbase, epnum);
+		if (is_in)
+			tmp = musb_readw(regs, MUSB_TXCSR)
+						& MUSB_TXCSR_P_SENDSTALL;
+		else
+			tmp = musb_readw(regs, MUSB_RXCSR)
+						& MUSB_RXCSR_P_SENDSTALL;
+		musb_ep_select(mbase, 0);
+
+		result[0] = tmp ? 1 : 0;
+		} break;
+
+	default:
+		/* class, vendor, etc ... delegate */
+		handled = 0;
+		break;
+	}
+
+	/* fill up the fifo; caller updates csr0 */
+	if (handled > 0) {
+		u16	len = le16_to_cpu(ctrlrequest->wLength);
+
+		if (len > 2)
+			len = 2;
+		musb_write_fifo(&musb->endpoints[0], len, result);
+	}
+
+	return handled;
+}
+
+/*
+ * handle a control-IN request, the end0 buffer contains the current request
+ * that is supposed to be a standard control request. Assumes the fifo to
+ * be at least 2 bytes long.
+ *
+ * @return 0 if the request was NOT HANDLED,
+ * < 0 when error
+ * > 0 when the request is processed
+ *
+ * Context:  caller holds controller lock
+ */
+static int
+service_in_request(struct musb *musb, const struct usb_ctrlrequest *ctrlrequest)
+{
+	int handled = 0;	/* not handled */
+
+	if ((ctrlrequest->bRequestType & USB_TYPE_MASK)
+			== USB_TYPE_STANDARD) {
+		switch (ctrlrequest->bRequest) {
+		case USB_REQ_GET_STATUS:
+			handled = service_tx_status_request(musb,
+					ctrlrequest);
+			break;
+
+		/* case USB_REQ_SYNC_FRAME: */
+
+		default:
+			break;
+		}
+	}
+	return handled;
+}
+
+/*
+ * Context:  caller holds controller lock
+ */
+static void musb_g_ep0_giveback(struct musb *musb, struct usb_request *req)
+{
+	musb_g_giveback(&musb->endpoints[0].ep_in, req, 0);
+}
+
+/*
+ * Tries to start B-device HNP negotiation if enabled via sysfs
+ */
+static inline void musb_try_b_hnp_enable(struct musb *musb)
+{
+	void __iomem	*mbase = musb->mregs;
+	u8		devctl;
+
+	dev_dbg(musb->controller, "HNP: Setting HR\n");
+	devctl = musb_readb(mbase, MUSB_DEVCTL);
+	musb_writeb(mbase, MUSB_DEVCTL, devctl | MUSB_DEVCTL_HR);
+}
+
+/*
+ * Handle all control requests with no DATA stage, including standard
+ * requests such as:
+ * USB_REQ_SET_CONFIGURATION, USB_REQ_SET_INTERFACE, unrecognized
+ *	always delegated to the gadget driver
+ * USB_REQ_SET_ADDRESS, USB_REQ_CLEAR_FEATURE, USB_REQ_SET_FEATURE
+ *	always handled here, except for class/vendor/... features
+ *
+ * Context:  caller holds controller lock
+ */
+static int
+service_zero_data_request(struct musb *musb,
+		struct usb_ctrlrequest *ctrlrequest)
+__releases(musb->lock)
+__acquires(musb->lock)
+{
+	int handled = -EINVAL;
+	void __iomem *mbase = musb->mregs;
+	const u8 recip = ctrlrequest->bRequestType & USB_RECIP_MASK;
+
+	/* the gadget driver handles everything except what we MUST handle */
+	if ((ctrlrequest->bRequestType & USB_TYPE_MASK)
+			== USB_TYPE_STANDARD) {
+		switch (ctrlrequest->bRequest) {
+		case USB_REQ_SET_ADDRESS:
+			/* change it after the status stage */
+			musb->set_address = true;
+			musb->address = (u8) (ctrlrequest->wValue & 0x7f);
+			handled = 1;
+			break;
+
+		case USB_REQ_CLEAR_FEATURE:
+			switch (recip) {
+			case USB_RECIP_DEVICE:
+				if (ctrlrequest->wValue
+						!= USB_DEVICE_REMOTE_WAKEUP)
+					break;
+				musb->may_wakeup = 0;
+				handled = 1;
+				break;
+			case USB_RECIP_INTERFACE:
+				break;
+			case USB_RECIP_ENDPOINT:{
+				const u8		epnum =
+					ctrlrequest->wIndex & 0x0f;
+				struct musb_ep		*musb_ep;
+				struct musb_hw_ep	*ep;
+				struct musb_request	*request;
+				void __iomem		*regs;
+				int			is_in;
+				u16			csr;
+
+				if (epnum == 0 || epnum >= MUSB_C_NUM_EPS ||
+				    ctrlrequest->wValue != USB_ENDPOINT_HALT)
+					break;
+
+				ep = musb->endpoints + epnum;
+				regs = ep->regs;
+				is_in = ctrlrequest->wIndex & USB_DIR_IN;
+				if (is_in)
+					musb_ep = &ep->ep_in;
+				else
+					musb_ep = &ep->ep_out;
+				if (!musb_ep->desc)
+					break;
+
+				handled = 1;
+				/* Ignore request if endpoint is wedged */
+				if (musb_ep->wedged)
+					break;
+
+				musb_ep_select(mbase, epnum);
+				if (is_in) {
+					csr  = musb_readw(regs, MUSB_TXCSR);
+					csr |= MUSB_TXCSR_CLRDATATOG |
+					       MUSB_TXCSR_P_WZC_BITS;
+					csr &= ~(MUSB_TXCSR_P_SENDSTALL |
+						 MUSB_TXCSR_P_SENTSTALL |
+						 MUSB_TXCSR_TXPKTRDY);
+					musb_writew(regs, MUSB_TXCSR, csr);
+				} else {
+					csr  = musb_readw(regs, MUSB_RXCSR);
+					csr |= MUSB_RXCSR_CLRDATATOG |
+					       MUSB_RXCSR_P_WZC_BITS;
+					csr &= ~(MUSB_RXCSR_P_SENDSTALL |
+						 MUSB_RXCSR_P_SENTSTALL);
+					musb_writew(regs, MUSB_RXCSR, csr);
+				}
+
+				/* Maybe start the first request in the queue */
+				request = next_request(musb_ep);
+				if (!musb_ep->busy && request) {
+					dev_dbg(musb->controller, "restarting the request\n");
+					musb_ep_restart(musb, request);
+				}
+
+				/* select ep0 again */
+				musb_ep_select(mbase, 0);
+				} break;
+			default:
+				/* class, vendor, etc ... delegate */
+				handled = 0;
+				break;
+			}
+			break;
+
+		case USB_REQ_SET_FEATURE:
+			switch (recip) {
+			case USB_RECIP_DEVICE:
+				handled = 1;
+				switch (ctrlrequest->wValue) {
+				case USB_DEVICE_REMOTE_WAKEUP:
+					musb->may_wakeup = 1;
+					break;
+				case USB_DEVICE_TEST_MODE:
+					if (musb->g.speed != USB_SPEED_HIGH)
+						goto stall;
+					if (ctrlrequest->wIndex & 0xff)
+						goto stall;
+
+					switch (ctrlrequest->wIndex >> 8) {
+					case 1:
+						pr_debug("TEST_J\n");
+						/* TEST_J */
+						musb->test_mode_nr =
+							MUSB_TEST_J;
+						break;
+					case 2:
+						/* TEST_K */
+						pr_debug("TEST_K\n");
+						musb->test_mode_nr =
+							MUSB_TEST_K;
+						break;
+					case 3:
+						/* TEST_SE0_NAK */
+						pr_debug("TEST_SE0_NAK\n");
+						musb->test_mode_nr =
+							MUSB_TEST_SE0_NAK;
+						break;
+					case 4:
+						/* TEST_PACKET */
+						pr_debug("TEST_PACKET\n");
+						musb->test_mode_nr =
+							MUSB_TEST_PACKET;
+						break;
+
+					case 0xc0:
+						/* TEST_FORCE_HS */
+						pr_debug("TEST_FORCE_HS\n");
+						musb->test_mode_nr =
+							MUSB_TEST_FORCE_HS;
+						break;
+					case 0xc1:
+						/* TEST_FORCE_FS */
+						pr_debug("TEST_FORCE_FS\n");
+						musb->test_mode_nr =
+							MUSB_TEST_FORCE_FS;
+						break;
+					case 0xc2:
+						/* TEST_FIFO_ACCESS */
+						pr_debug("TEST_FIFO_ACCESS\n");
+						musb->test_mode_nr =
+							MUSB_TEST_FIFO_ACCESS;
+						break;
+					case 0xc3:
+						/* TEST_FORCE_HOST */
+						pr_debug("TEST_FORCE_HOST\n");
+						musb->test_mode_nr =
+							MUSB_TEST_FORCE_HOST;
+						break;
+					default:
+						goto stall;
+					}
+
+					/* enter test mode after irq */
+					if (handled > 0)
+						musb->test_mode = true;
+					break;
+				case USB_DEVICE_B_HNP_ENABLE:
+					if (!musb->g.is_otg)
+						goto stall;
+					musb->g.b_hnp_enable = 1;
+					musb_try_b_hnp_enable(musb);
+					break;
+				case USB_DEVICE_A_HNP_SUPPORT:
+					if (!musb->g.is_otg)
+						goto stall;
+					musb->g.a_hnp_support = 1;
+					break;
+				case USB_DEVICE_A_ALT_HNP_SUPPORT:
+					if (!musb->g.is_otg)
+						goto stall;
+					musb->g.a_alt_hnp_support = 1;
+					break;
+				case USB_DEVICE_DEBUG_MODE:
+					handled = 0;
+					break;
+stall:
+				default:
+					handled = -EINVAL;
+					break;
+				}
+				break;
+
+			case USB_RECIP_INTERFACE:
+				break;
+
+			case USB_RECIP_ENDPOINT:{
+				const u8		epnum =
+					ctrlrequest->wIndex & 0x0f;
+				struct musb_ep		*musb_ep;
+				struct musb_hw_ep	*ep;
+				void __iomem		*regs;
+				int			is_in;
+				u16			csr;
+
+				if (epnum == 0 || epnum >= MUSB_C_NUM_EPS ||
+				    ctrlrequest->wValue	!= USB_ENDPOINT_HALT)
+					break;
+
+				ep = musb->endpoints + epnum;
+				regs = ep->regs;
+				is_in = ctrlrequest->wIndex & USB_DIR_IN;
+				if (is_in)
+					musb_ep = &ep->ep_in;
+				else
+					musb_ep = &ep->ep_out;
+				if (!musb_ep->desc)
+					break;
+
+				musb_ep_select(mbase, epnum);
+				if (is_in) {
+					csr = musb_readw(regs, MUSB_TXCSR);
+					if (csr & MUSB_TXCSR_FIFONOTEMPTY)
+						csr |= MUSB_TXCSR_FLUSHFIFO;
+					csr |= MUSB_TXCSR_P_SENDSTALL
+						| MUSB_TXCSR_CLRDATATOG
+						| MUSB_TXCSR_P_WZC_BITS;
+					musb_writew(regs, MUSB_TXCSR, csr);
+				} else {
+					csr = musb_readw(regs, MUSB_RXCSR);
+					csr |= MUSB_RXCSR_P_SENDSTALL
+						| MUSB_RXCSR_FLUSHFIFO
+						| MUSB_RXCSR_CLRDATATOG
+						| MUSB_RXCSR_P_WZC_BITS;
+					musb_writew(regs, MUSB_RXCSR, csr);
+				}
+
+				/* select ep0 again */
+				musb_ep_select(mbase, 0);
+				handled = 1;
+				} break;
+
+			default:
+				/* class, vendor, etc ... delegate */
+				handled = 0;
+				break;
+			}
+			break;
+		default:
+			/* delegate SET_CONFIGURATION, etc */
+			handled = 0;
+		}
+	} else
+		handled = 0;
+	return handled;
+}
+
+/* we have an ep0out data packet
+ * Context:  caller holds controller lock
+ */
+static void ep0_rxstate(struct musb *musb)
+{
+	void __iomem		*regs = musb->control_ep->regs;
+	struct musb_request	*request;
+	struct usb_request	*req;
+	u16			count, csr;
+
+	request = next_ep0_request(musb);
+	req = &request->request;
+
+	/* read packet and ack; or stall because of gadget driver bug:
+	 * should have provided the rx buffer before setup() returned.
+	 */
+	if (req) {
+		void		*buf = req->buf + req->actual;
+		unsigned	len = req->length - req->actual;
+
+		/* read the buffer */
+		count = musb_readb(regs, MUSB_COUNT0);
+		if (count > len) {
+			req->status = -EOVERFLOW;
+			count = len;
+		}
+		musb_read_fifo(&musb->endpoints[0], count, buf);
+		req->actual += count;
+		csr = MUSB_CSR0_P_SVDRXPKTRDY;
+		if (count < 64 || req->actual == req->length) {
+			musb->ep0_state = MUSB_EP0_STAGE_STATUSIN;
+			csr |= MUSB_CSR0_P_DATAEND;
+		} else
+			req = NULL;
+	} else
+		csr = MUSB_CSR0_P_SVDRXPKTRDY | MUSB_CSR0_P_SENDSTALL;
+
+
+	/* Completion handler may choose to stall, e.g. because the
+	 * message just received holds invalid data.
+	 */
+	if (req) {
+		musb->ackpend = csr;
+		musb_g_ep0_giveback(musb, req);
+		if (!musb->ackpend)
+			return;
+		musb->ackpend = 0;
+	}
+	musb_ep_select(musb->mregs, 0);
+	musb_writew(regs, MUSB_CSR0, csr);
+}
+
+/*
+ * transmitting to the host (IN), this code might be called from IRQ
+ * and from kernel thread.
+ *
+ * Context:  caller holds controller lock
+ */
+static void ep0_txstate(struct musb *musb)
+{
+	void __iomem		*regs = musb->control_ep->regs;
+	struct musb_request	*req = next_ep0_request(musb);
+	struct usb_request	*request;
+	u16			csr = MUSB_CSR0_TXPKTRDY;
+	u8			*fifo_src;
+	u8			fifo_count;
+
+	if (!req) {
+		/* WARN_ON(1); */
+		dev_dbg(musb->controller, "odd; csr0 %04x\n", musb_readw(regs, MUSB_CSR0));
+		return;
+	}
+
+	request = &req->request;
+
+	/* load the data */
+	fifo_src = (u8 *) request->buf + request->actual;
+	fifo_count = min((unsigned) MUSB_EP0_FIFOSIZE,
+		request->length - request->actual);
+	musb_write_fifo(&musb->endpoints[0], fifo_count, fifo_src);
+	request->actual += fifo_count;
+
+	/* update the flags */
+	if (fifo_count < MUSB_MAX_END0_PACKET
+			|| (request->actual == request->length
+				&& !request->zero)) {
+		musb->ep0_state = MUSB_EP0_STAGE_STATUSOUT;
+		csr |= MUSB_CSR0_P_DATAEND;
+	} else
+		request = NULL;
+
+	/* report completions as soon as the fifo's loaded; there's no
+	 * win in waiting till this last packet gets acked.  (other than
+	 * very precise fault reporting, needed by USB TMC; possible with
+	 * this hardware, but not usable from portable gadget drivers.)
+	 */
+	if (request) {
+		musb->ackpend = csr;
+		musb_g_ep0_giveback(musb, request);
+		if (!musb->ackpend)
+			return;
+		musb->ackpend = 0;
+	}
+
+	/* send it out, triggering a "txpktrdy cleared" irq */
+	musb_ep_select(musb->mregs, 0);
+	musb_writew(regs, MUSB_CSR0, csr);
+}
+
+/*
+ * Read a SETUP packet (struct usb_ctrlrequest) from the hardware.
+ * Fields are left in USB byte-order.
+ *
+ * Context:  caller holds controller lock.
+ */
+static void
+musb_read_setup(struct musb *musb, struct usb_ctrlrequest *req)
+{
+	struct musb_request	*r;
+	void __iomem		*regs = musb->control_ep->regs;
+
+	musb_read_fifo(&musb->endpoints[0], sizeof *req, (u8 *)req);
+
+	/* NOTE:  earlier 2.6 versions changed setup packets to host
+	 * order, but now USB packets always stay in USB byte order.
+	 */
+	dev_dbg(musb->controller, "SETUP req%02x.%02x v%04x i%04x l%d\n",
+		req->bRequestType,
+		req->bRequest,
+		le16_to_cpu(req->wValue),
+		le16_to_cpu(req->wIndex),
+		le16_to_cpu(req->wLength));
+
+	/* clean up any leftover transfers */
+	r = next_ep0_request(musb);
+	if (r)
+		musb_g_ep0_giveback(musb, &r->request);
+
+	/* For zero-data requests we want to delay the STATUS stage to
+	 * avoid SETUPEND errors.  If we read data (OUT), delay accepting
+	 * packets until there's a buffer to store them in.
+	 *
+	 * If we write data, the controller acts happier if we enable
+	 * the TX FIFO right away, and give the controller a moment
+	 * to switch modes...
+	 */
+	musb->set_address = false;
+	musb->ackpend = MUSB_CSR0_P_SVDRXPKTRDY;
+	if (req->wLength == 0) {
+		if (req->bRequestType & USB_DIR_IN)
+			musb->ackpend |= MUSB_CSR0_TXPKTRDY;
+		musb->ep0_state = MUSB_EP0_STAGE_ACKWAIT;
+	} else if (req->bRequestType & USB_DIR_IN) {
+		musb->ep0_state = MUSB_EP0_STAGE_TX;
+		musb_writew(regs, MUSB_CSR0, MUSB_CSR0_P_SVDRXPKTRDY);
+		while ((musb_readw(regs, MUSB_CSR0)
+				& MUSB_CSR0_RXPKTRDY) != 0)
+			cpu_relax();
+		musb->ackpend = 0;
+	} else
+		musb->ep0_state = MUSB_EP0_STAGE_RX;
+}
+
+static int
+forward_to_driver(struct musb *musb, const struct usb_ctrlrequest *ctrlrequest)
+__releases(musb->lock)
+__acquires(musb->lock)
+{
+	int retval;
+	if (!musb->gadget_driver)
+		return -EOPNOTSUPP;
+	spin_unlock(&musb->lock);
+	retval = musb->gadget_driver->setup(&musb->g, ctrlrequest);
+	spin_lock(&musb->lock);
+	return retval;
+}
+
+/*
+ * Handle peripheral ep0 interrupt
+ *
+ * Context: irq handler; we won't re-enter the driver that way.
+ */
+irqreturn_t musb_g_ep0_irq(struct musb *musb)
+{
+	u16		csr;
+	u16		len;
+	void __iomem	*mbase = musb->mregs;
+	void __iomem	*regs = musb->endpoints[0].regs;
+	irqreturn_t	retval = IRQ_NONE;
+
+	musb_ep_select(mbase, 0);	/* select ep0 */
+	csr = musb_readw(regs, MUSB_CSR0);
+	len = musb_readb(regs, MUSB_COUNT0);
+
+	dev_dbg(musb->controller, "csr %04x, count %d, myaddr %d, ep0stage %s\n",
+			csr, len,
+			musb_readb(mbase, MUSB_FADDR),
+			decode_ep0stage(musb->ep0_state));
+
+	if (csr & MUSB_CSR0_P_DATAEND) {
+		/*
+		 * If DATAEND is set we should not call the callback,
+		 * hence the status stage is not complete.
+		 */
+		return IRQ_HANDLED;
+	}
+
+	/* I sent a stall.. need to acknowledge it now.. */
+	if (csr & MUSB_CSR0_P_SENTSTALL) {
+		musb_writew(regs, MUSB_CSR0,
+				csr & ~MUSB_CSR0_P_SENTSTALL);
+		retval = IRQ_HANDLED;
+		musb->ep0_state = MUSB_EP0_STAGE_IDLE;
+		csr = musb_readw(regs, MUSB_CSR0);
+	}
+
+	/* request ended "early" */
+	if (csr & MUSB_CSR0_P_SETUPEND) {
+		musb_writew(regs, MUSB_CSR0, MUSB_CSR0_P_SVDSETUPEND);
+		retval = IRQ_HANDLED;
+		/* Transition into the early status phase */
+		switch (musb->ep0_state) {
+		case MUSB_EP0_STAGE_TX:
+			musb->ep0_state = MUSB_EP0_STAGE_STATUSOUT;
+			break;
+		case MUSB_EP0_STAGE_RX:
+			musb->ep0_state = MUSB_EP0_STAGE_STATUSIN;
+			break;
+		default:
+			ERR("SetupEnd came in a wrong ep0stage %s\n",
+			    decode_ep0stage(musb->ep0_state));
+		}
+		csr = musb_readw(regs, MUSB_CSR0);
+		/* NOTE:  request may need completion */
+	}
+
+	/* docs from Mentor only describe tx, rx, and idle/setup states.
+	 * we need to handle nuances around status stages, and also the
+	 * case where status and setup stages come back-to-back ...
+	 */
+	switch (musb->ep0_state) {
+
+	case MUSB_EP0_STAGE_TX:
+		/* irq on clearing txpktrdy */
+		if ((csr & MUSB_CSR0_TXPKTRDY) == 0) {
+			ep0_txstate(musb);
+			retval = IRQ_HANDLED;
+		}
+		break;
+
+	case MUSB_EP0_STAGE_RX:
+		/* irq on set rxpktrdy */
+		if (csr & MUSB_CSR0_RXPKTRDY) {
+			ep0_rxstate(musb);
+			retval = IRQ_HANDLED;
+		}
+		break;
+
+	case MUSB_EP0_STAGE_STATUSIN:
+		/* end of sequence #2 (OUT/RX state) or #3 (no data) */
+
+		/* update address (if needed) only @ the end of the
+		 * status phase per usb spec, which also guarantees
+		 * we get 10 msec to receive this irq... until this
+		 * is done we won't see the next packet.
+		 */
+		if (musb->set_address) {
+			musb->set_address = false;
+			musb_writeb(mbase, MUSB_FADDR, musb->address);
+		}
+
+		/* enter test mode if needed (exit by reset) */
+		else if (musb->test_mode) {
+			dev_dbg(musb->controller, "entering TESTMODE\n");
+
+			if (MUSB_TEST_PACKET == musb->test_mode_nr)
+				musb_load_testpacket(musb);
+
+			musb_writeb(mbase, MUSB_TESTMODE,
+					musb->test_mode_nr);
+		}
+		/* FALLTHROUGH */
+
+	case MUSB_EP0_STAGE_STATUSOUT:
+		/* end of sequence #1: write to host (TX state) */
+		{
+			struct musb_request	*req;
+
+			req = next_ep0_request(musb);
+			if (req)
+				musb_g_ep0_giveback(musb, &req->request);
+		}
+
+		/*
+		 * In case when several interrupts can get coalesced,
+		 * check to see if we've already received a SETUP packet...
+		 */
+		if (csr & MUSB_CSR0_RXPKTRDY)
+			goto setup;
+
+		retval = IRQ_HANDLED;
+		musb->ep0_state = MUSB_EP0_STAGE_IDLE;
+		break;
+
+	case MUSB_EP0_STAGE_IDLE:
+		/*
+		 * This state is typically (but not always) indiscernible
+		 * from the status states since the corresponding interrupts
+		 * tend to happen within too little period of time (with only
+		 * a zero-length packet in between) and so get coalesced...
+		 */
+		retval = IRQ_HANDLED;
+		musb->ep0_state = MUSB_EP0_STAGE_SETUP;
+		/* FALLTHROUGH */
+
+	case MUSB_EP0_STAGE_SETUP:
+setup:
+		if (csr & MUSB_CSR0_RXPKTRDY) {
+			struct usb_ctrlrequest	setup;
+			int			handled = 0;
+
+			if (len != 8) {
+				ERR("SETUP packet len %d != 8 ?\n", len);
+				break;
+			}
+			musb_read_setup(musb, &setup);
+			retval = IRQ_HANDLED;
+
+			/* sometimes the RESET won't be reported */
+			if (unlikely(musb->g.speed == USB_SPEED_UNKNOWN)) {
+				u8	power;
+
+				printk(KERN_NOTICE "%s: peripheral reset "
+						"irq lost!\n",
+						musb_driver_name);
+				power = musb_readb(mbase, MUSB_POWER);
+				musb->g.speed = (power & MUSB_POWER_HSMODE)
+					? USB_SPEED_HIGH : USB_SPEED_FULL;
+
+			}
+
+			switch (musb->ep0_state) {
+
+			/* sequence #3 (no data stage), includes requests
+			 * we can't forward (notably SET_ADDRESS and the
+			 * device/endpoint feature set/clear operations)
+			 * plus SET_CONFIGURATION and others we must
+			 */
+			case MUSB_EP0_STAGE_ACKWAIT:
+				handled = service_zero_data_request(
+						musb, &setup);
+
+				/*
+				 * We're expecting no data in any case, so
+				 * always set the DATAEND bit -- doing this
+				 * here helps avoid SetupEnd interrupt coming
+				 * in the idle stage when we're stalling...
+				 */
+				musb->ackpend |= MUSB_CSR0_P_DATAEND;
+
+				/* status stage might be immediate */
+				if (handled > 0)
+					musb->ep0_state =
+						MUSB_EP0_STAGE_STATUSIN;
+				break;
+
+			/* sequence #1 (IN to host), includes GET_STATUS
+			 * requests that we can't forward, GET_DESCRIPTOR
+			 * and others that we must
+			 */
+			case MUSB_EP0_STAGE_TX:
+				handled = service_in_request(musb, &setup);
+				if (handled > 0) {
+					musb->ackpend = MUSB_CSR0_TXPKTRDY
+						| MUSB_CSR0_P_DATAEND;
+					musb->ep0_state =
+						MUSB_EP0_STAGE_STATUSOUT;
+				}
+				break;
+
+			/* sequence #2 (OUT from host), always forward */
+			default:		/* MUSB_EP0_STAGE_RX */
+				break;
+			}
+
+			dev_dbg(musb->controller, "handled %d, csr %04x, ep0stage %s\n",
+				handled, csr,
+				decode_ep0stage(musb->ep0_state));
+
+			/* unless we need to delegate this to the gadget
+			 * driver, we know how to wrap this up:  csr0 has
+			 * not yet been written.
+			 */
+			if (handled < 0)
+				goto stall;
+			else if (handled > 0)
+				goto finish;
+
+			handled = forward_to_driver(musb, &setup);
+			if (handled < 0) {
+				musb_ep_select(mbase, 0);
+stall:
+				dev_dbg(musb->controller, "stall (%d)\n", handled);
+				musb->ackpend |= MUSB_CSR0_P_SENDSTALL;
+				musb->ep0_state = MUSB_EP0_STAGE_IDLE;
+finish:
+				musb_writew(regs, MUSB_CSR0,
+						musb->ackpend);
+				musb->ackpend = 0;
+			}
+		}
+		break;
+
+	case MUSB_EP0_STAGE_ACKWAIT:
+		/* This should not happen. But happens with tusb6010 with
+		 * g_file_storage and high speed. Do nothing.
+		 */
+		retval = IRQ_HANDLED;
+		break;
+
+	default:
+		/* "can't happen" */
+		WARN_ON(1);
+		musb_writew(regs, MUSB_CSR0, MUSB_CSR0_P_SENDSTALL);
+		musb->ep0_state = MUSB_EP0_STAGE_IDLE;
+		break;
+	}
+
+	return retval;
+}
+
+
+static int
+musb_g_ep0_enable(struct usb_ep *ep, const struct usb_endpoint_descriptor *desc)
+{
+	/* always enabled */
+	return -EINVAL;
+}
+
+static int musb_g_ep0_disable(struct usb_ep *e)
+{
+	/* always enabled */
+	return -EINVAL;
+}
+
+static int
+musb_g_ep0_queue(struct usb_ep *e, struct usb_request *r, gfp_t gfp_flags)
+{
+	struct musb_ep		*ep;
+	struct musb_request	*req;
+	struct musb		*musb;
+	int			status;
+	unsigned long		lockflags;
+	void __iomem		*regs;
+
+	if (!e || !r)
+		return -EINVAL;
+
+	ep = to_musb_ep(e);
+	musb = ep->musb;
+	regs = musb->control_ep->regs;
+
+	req = to_musb_request(r);
+	req->musb = musb;
+	req->request.actual = 0;
+	req->request.status = -EINPROGRESS;
+	req->tx = ep->is_in;
+
+	spin_lock_irqsave(&musb->lock, lockflags);
+
+	if (!list_empty(&ep->req_list)) {
+		status = -EBUSY;
+		goto cleanup;
+	}
+
+	switch (musb->ep0_state) {
+	case MUSB_EP0_STAGE_RX:		/* control-OUT data */
+	case MUSB_EP0_STAGE_TX:		/* control-IN data */
+	case MUSB_EP0_STAGE_ACKWAIT:	/* zero-length data */
+		status = 0;
+		break;
+	default:
+		dev_dbg(musb->controller, "ep0 request queued in state %d\n",
+				musb->ep0_state);
+		status = -EINVAL;
+		goto cleanup;
+	}
+
+	/* add request to the list */
+	list_add_tail(&req->list, &ep->req_list);
+
+	dev_dbg(musb->controller, "queue to %s (%s), length=%d\n",
+			ep->name, ep->is_in ? "IN/TX" : "OUT/RX",
+			req->request.length);
+
+	musb_ep_select(musb->mregs, 0);
+
+	/* sequence #1, IN ... start writing the data */
+	if (musb->ep0_state == MUSB_EP0_STAGE_TX)
+		ep0_txstate(musb);
+
+	/* sequence #3, no-data ... issue IN status */
+	else if (musb->ep0_state == MUSB_EP0_STAGE_ACKWAIT) {
+		if (req->request.length)
+			status = -EINVAL;
+		else {
+			musb->ep0_state = MUSB_EP0_STAGE_STATUSIN;
+			musb_writew(regs, MUSB_CSR0,
+					musb->ackpend | MUSB_CSR0_P_DATAEND);
+			musb->ackpend = 0;
+			musb_g_ep0_giveback(ep->musb, r);
+		}
+
+	/* else for sequence #2 (OUT), caller provides a buffer
+	 * before the next packet arrives.  deferred responses
+	 * (after SETUP is acked) are racey.
+	 */
+	} else if (musb->ackpend) {
+		musb_writew(regs, MUSB_CSR0, musb->ackpend);
+		musb->ackpend = 0;
+	}
+
+cleanup:
+	spin_unlock_irqrestore(&musb->lock, lockflags);
+	return status;
+}
+
+static int musb_g_ep0_dequeue(struct usb_ep *ep, struct usb_request *req)
+{
+	/* we just won't support this */
+	return -EINVAL;
+}
+
+static int musb_g_ep0_halt(struct usb_ep *e, int value)
+{
+	struct musb_ep		*ep;
+	struct musb		*musb;
+	void __iomem		*base, *regs;
+	unsigned long		flags;
+	int			status;
+	u16			csr;
+
+	if (!e || !value)
+		return -EINVAL;
+
+	ep = to_musb_ep(e);
+	musb = ep->musb;
+	base = musb->mregs;
+	regs = musb->control_ep->regs;
+	status = 0;
+
+	spin_lock_irqsave(&musb->lock, flags);
+
+	if (!list_empty(&ep->req_list)) {
+		status = -EBUSY;
+		goto cleanup;
+	}
+
+	musb_ep_select(base, 0);
+	csr = musb->ackpend;
+
+	switch (musb->ep0_state) {
+
+	/* Stalls are usually issued after parsing SETUP packet, either
+	 * directly in irq context from setup() or else later.
+	 */
+	case MUSB_EP0_STAGE_TX:		/* control-IN data */
+	case MUSB_EP0_STAGE_ACKWAIT:	/* STALL for zero-length data */
+	case MUSB_EP0_STAGE_RX:		/* control-OUT data */
+		csr = musb_readw(regs, MUSB_CSR0);
+		/* FALLTHROUGH */
+
+	/* It's also OK to issue stalls during callbacks when a non-empty
+	 * DATA stage buffer has been read (or even written).
+	 */
+	case MUSB_EP0_STAGE_STATUSIN:	/* control-OUT status */
+	case MUSB_EP0_STAGE_STATUSOUT:	/* control-IN status */
+
+		csr |= MUSB_CSR0_P_SENDSTALL;
+		musb_writew(regs, MUSB_CSR0, csr);
+		musb->ep0_state = MUSB_EP0_STAGE_IDLE;
+		musb->ackpend = 0;
+		break;
+	default:
+		dev_dbg(musb->controller, "ep0 can't halt in state %d\n", musb->ep0_state);
+		status = -EINVAL;
+	}
+
+cleanup:
+	spin_unlock_irqrestore(&musb->lock, flags);
+	return status;
+}
+
+const struct usb_ep_ops musb_g_ep0_ops = {
+	.enable		= musb_g_ep0_enable,
+	.disable	= musb_g_ep0_disable,
+	.alloc_request	= musb_alloc_request,
+	.free_request	= musb_free_request,
+	.queue		= musb_g_ep0_queue,
+	.dequeue	= musb_g_ep0_dequeue,
+	.set_halt	= musb_g_ep0_halt,
+};