Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1058 insertions, 0 deletions

diff --git a/drivers/usb/musb/musb_gadget_ep0.c b/drivers/usb/musb/musb_gadget_ep0.c
new file mode 100644
index 000000000..6d7336727
--- /dev/null
+++ b/drivers/usb/musb/musb_gadget_ep0.c
@@ -0,0 +1,1058 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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>
+ */
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/timer.h>
+#include <linux/spinlock.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+
+#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->g.is_selfpowered << 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;
+		epnum &= 0x0f;
+		if (epnum >= MUSB_C_NUM_EPS) {
+			handled = -EINVAL;
+			break;
+		}
+
+		if (is_in)
+			ep = &musb->endpoints[epnum].ep_in;
+		else
+			ep = &musb->endpoints[epnum].ep_out;
+		regs = musb->endpoints[epnum].regs;
+
+		if (!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;
+
+	musb_dbg(musb, "HNP: Setting HR");
+	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) {
+					musb_dbg(musb, "restarting the request");
+					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 USB_TEST_J:
+						pr_debug("USB_TEST_J\n");
+						musb->test_mode_nr =
+							MUSB_TEST_J;
+						break;
+					case USB_TEST_K:
+						pr_debug("USB_TEST_K\n");
+						musb->test_mode_nr =
+							MUSB_TEST_K;
+						break;
+					case USB_TEST_SE0_NAK:
+						pr_debug("USB_TEST_SE0_NAK\n");
+						musb->test_mode_nr =
+							MUSB_TEST_SE0_NAK;
+						break;
+					case USB_TEST_PACKET:
+						pr_debug("USB_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;
+		}
+		if (count > 0) {
+			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); */
+		musb_dbg(musb, "odd; csr0 %04x", 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.
+	 */
+	musb_dbg(musb, "SETUP req%02x.%02x v%04x i%04x l%d",
+		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);
+
+	musb_dbg(musb, "csr %04x, count %d, ep0stage %s",
+			csr, len, 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) {
+			musb_dbg(musb, "entering TESTMODE");
+
+			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;
+			}
+
+			musb_dbg(musb, "handled %d, csr %04x, ep0stage %s",
+				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:
+				musb_dbg(musb, "stall (%d)", 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:
+		musb_dbg(musb, "ep0 request queued in state %d",
+				musb->ep0_state);
+		status = -EINVAL;
+		goto cleanup;
+	}
+
+	/* add request to the list */
+	list_add_tail(&req->list, &ep->req_list);
+
+	musb_dbg(musb, "queue to %s (%s), length=%d",
+			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:
+		musb_dbg(musb, "ep0 can't halt in state %d", 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,
+};