usb: Add MediaTek USB3 DRD driver

This patch adds support for the MediaTek USB3 controller
integrated into MT8173. It currently supports High-Speed
Peripheral Only mode.

Super-Speed Peripheral, Dual-Role Device and Host Only (xHCI)
modes will be added in the next patchs.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 791 insertions, 0 deletions

diff --git a/drivers/usb/mtu3/mtu3_gadget_ep0.c b/drivers/usb/mtu3/mtu3_gadget_ep0.c
new file mode 100644
index 000000000000..4e2c2babad20
--- /dev/null
+++ b/drivers/usb/mtu3/mtu3_gadget_ep0.c
@@ -0,0 +1,791 @@
+/*
+ * mtu3_gadget_ep0.c - MediaTek USB3 DRD peripheral driver ep0 handling
+ *
+ * Copyright (c) 2016 MediaTek Inc.
+ *
+ * Author:  Chunfeng.Yun <chunfeng.yun@mediatek.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include "mtu3.h"
+
+/* ep0 is always mtu3->in_eps[0] */
+#define	next_ep0_request(mtu)	next_request((mtu)->ep0)
+
+/* for high speed test mode; see USB 2.0 spec 7.1.20 */
+static const u8 mtu3_test_packet[53] = {
+	/* implicit SYNC then DATA0 to start */
+
+	/* JKJKJKJK x9 */
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	/* JJKKJJKK x8 */
+	0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
+	/* JJJJKKKK x8 */
+	0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee,
+	/* JJJJJJJKKKKKKK x8 */
+	0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+	/* JJJJJJJK x8 */
+	0x7f, 0xbf, 0xdf, 0xef, 0xf7, 0xfb, 0xfd,
+	/* JKKKKKKK x10, JK */
+	0xfc, 0x7e, 0xbf, 0xdf, 0xef, 0xf7, 0xfb, 0xfd, 0x7e,
+	/* implicit CRC16 then EOP to end */
+};
+
+static char *decode_ep0_state(struct mtu3 *mtu)
+{
+	switch (mtu->ep0_state) {
+	case MU3D_EP0_STATE_SETUP:
+		return "SETUP";
+	case MU3D_EP0_STATE_TX:
+		return "IN";
+	case MU3D_EP0_STATE_RX:
+		return "OUT";
+	case MU3D_EP0_STATE_TX_END:
+		return "TX-END";
+	case MU3D_EP0_STATE_STALL:
+		return "STALL";
+	default:
+		return "??";
+	}
+}
+
+static void ep0_req_giveback(struct mtu3 *mtu, struct usb_request *req)
+{
+	mtu3_req_complete(mtu->ep0, req, 0);
+}
+
+static int
+forward_to_driver(struct mtu3 *mtu, const struct usb_ctrlrequest *setup)
+__releases(mtu->lock)
+__acquires(mtu->lock)
+{
+	int ret;
+
+	if (!mtu->gadget_driver)
+		return -EOPNOTSUPP;
+
+	spin_unlock(&mtu->lock);
+	ret = mtu->gadget_driver->setup(&mtu->g, setup);
+	spin_lock(&mtu->lock);
+
+	dev_dbg(mtu->dev, "%s ret %d\n", __func__, ret);
+	return ret;
+}
+
+static void ep0_write_fifo(struct mtu3_ep *mep, const u8 *src, u16 len)
+{
+	void __iomem *fifo = mep->mtu->mac_base + U3D_FIFO0;
+	u16 index = 0;
+
+	dev_dbg(mep->mtu->dev, "%s: ep%din, len=%d, buf=%p\n",
+		__func__, mep->epnum, len, src);
+
+	if (len >= 4) {
+		iowrite32_rep(fifo, src, len >> 2);
+		index = len & ~0x03;
+	}
+	if (len & 0x02) {
+		writew(*(u16 *)&src[index], fifo);
+		index += 2;
+	}
+	if (len & 0x01)
+		writeb(src[index], fifo);
+}
+
+static void ep0_read_fifo(struct mtu3_ep *mep, u8 *dst, u16 len)
+{
+	void __iomem *fifo = mep->mtu->mac_base + U3D_FIFO0;
+	u32 value;
+	u16 index = 0;
+
+	dev_dbg(mep->mtu->dev, "%s: ep%dout len=%d buf=%p\n",
+		 __func__, mep->epnum, len, dst);
+
+	if (len >= 4) {
+		ioread32_rep(fifo, dst, len >> 2);
+		index = len & ~0x03;
+	}
+	if (len & 0x3) {
+		value = readl(fifo);
+		memcpy(&dst[index], &value, len & 0x3);
+	}
+
+}
+
+static void ep0_load_test_packet(struct mtu3 *mtu)
+{
+	/*
+	 * because the length of test packet is less than max packet of HS ep0,
+	 * write it into fifo directly.
+	 */
+	ep0_write_fifo(mtu->ep0, mtu3_test_packet, sizeof(mtu3_test_packet));
+}
+
+/*
+ * A. send STALL for setup transfer without data stage:
+ *		set SENDSTALL and SETUPPKTRDY at the same time;
+ * B. send STALL for other cases:
+ *		set SENDSTALL only.
+ */
+static void ep0_stall_set(struct mtu3_ep *mep0, bool set, u32 pktrdy)
+{
+	struct mtu3 *mtu = mep0->mtu;
+	void __iomem *mbase = mtu->mac_base;
+	u32 csr;
+
+	/* EP0_SENTSTALL is W1C */
+	csr = mtu3_readl(mbase, U3D_EP0CSR) & EP0_W1C_BITS;
+	if (set)
+		csr |= EP0_SENDSTALL | pktrdy;
+	else
+		csr = (csr & ~EP0_SENDSTALL) | EP0_SENTSTALL;
+	mtu3_writel(mtu->mac_base, U3D_EP0CSR, csr);
+
+	mtu->ep0_state = MU3D_EP0_STATE_SETUP;
+
+	dev_dbg(mtu->dev, "ep0: %s STALL, ep0_state: %s\n",
+		set ? "SEND" : "CLEAR", decode_ep0_state(mtu));
+}
+
+static int ep0_queue(struct mtu3_ep *mep0, struct mtu3_request *mreq);
+
+static void ep0_dummy_complete(struct usb_ep *ep, struct usb_request *req)
+{}
+
+static int
+ep0_get_status(struct mtu3 *mtu, const struct usb_ctrlrequest *setup)
+{
+	struct mtu3_ep *mep = NULL;
+	int handled = 1;
+	u8 result[2] = {0, 0};
+	u8 epnum = 0;
+	int is_in;
+
+	switch (setup->bRequestType & USB_RECIP_MASK) {
+	case USB_RECIP_DEVICE:
+		result[0] = mtu->is_self_powered << USB_DEVICE_SELF_POWERED;
+		result[0] |= mtu->may_wakeup << USB_DEVICE_REMOTE_WAKEUP;
+		break;
+	case USB_RECIP_INTERFACE:
+		break;
+	case USB_RECIP_ENDPOINT:
+		epnum = (u8) le16_to_cpu(setup->wIndex);
+		is_in = epnum & USB_DIR_IN;
+		epnum &= USB_ENDPOINT_NUMBER_MASK;
+
+		if (epnum >= mtu->num_eps) {
+			handled = -EINVAL;
+			break;
+		}
+		if (!epnum)
+			break;
+
+		mep = (is_in ? mtu->in_eps : mtu->out_eps) + epnum;
+		if (!mep->desc) {
+			handled = -EINVAL;
+			break;
+		}
+		if (mep->flags & MTU3_EP_STALL)
+			result[0] |= 1 << USB_ENDPOINT_HALT;
+
+		break;
+	default:
+		/* class, vendor, etc ... delegate */
+		handled = 0;
+		break;
+	}
+
+	if (handled > 0) {
+		int ret;
+
+		/* prepare a data stage for GET_STATUS */
+		dev_dbg(mtu->dev, "get_status=%x\n", *(u16 *)result);
+		memcpy(mtu->setup_buf, result, sizeof(result));
+		mtu->ep0_req.mep = mtu->ep0;
+		mtu->ep0_req.request.length = 2;
+		mtu->ep0_req.request.buf = &mtu->setup_buf;
+		mtu->ep0_req.request.complete = ep0_dummy_complete;
+		ret = ep0_queue(mtu->ep0, &mtu->ep0_req);
+		if (ret < 0)
+			handled = ret;
+	}
+	return handled;
+}
+
+static int handle_test_mode(struct mtu3 *mtu, struct usb_ctrlrequest *setup)
+{
+	void __iomem *mbase = mtu->mac_base;
+	int handled = 1;
+
+	switch (le16_to_cpu(setup->wIndex) >> 8) {
+	case TEST_J:
+		dev_dbg(mtu->dev, "TEST_J\n");
+		mtu->test_mode_nr = TEST_J_MODE;
+		break;
+	case TEST_K:
+		dev_dbg(mtu->dev, "TEST_K\n");
+		mtu->test_mode_nr = TEST_K_MODE;
+		break;
+	case TEST_SE0_NAK:
+		dev_dbg(mtu->dev, "TEST_SE0_NAK\n");
+		mtu->test_mode_nr = TEST_SE0_NAK_MODE;
+		break;
+	case TEST_PACKET:
+		dev_dbg(mtu->dev, "TEST_PACKET\n");
+		mtu->test_mode_nr = TEST_PACKET_MODE;
+		break;
+	default:
+		handled = -EINVAL;
+		goto out;
+	}
+
+	mtu->test_mode = true;
+
+	/* no TX completion interrupt, and need restart platform after test */
+	if (mtu->test_mode_nr == TEST_PACKET_MODE)
+		ep0_load_test_packet(mtu);
+
+	mtu3_writel(mbase, U3D_USB2_TEST_MODE, mtu->test_mode_nr);
+
+	mtu->ep0_state = MU3D_EP0_STATE_SETUP;
+
+out:
+	return handled;
+}
+
+static int ep0_handle_feature_dev(struct mtu3 *mtu,
+		struct usb_ctrlrequest *setup, bool set)
+{
+	int handled = -EINVAL;
+
+	switch (le16_to_cpu(setup->wValue)) {
+	case USB_DEVICE_REMOTE_WAKEUP:
+		mtu->may_wakeup = !!set;
+		handled = 1;
+		break;
+	case USB_DEVICE_TEST_MODE:
+		if (!set || (mtu->g.speed != USB_SPEED_HIGH) ||
+			(le16_to_cpu(setup->wIndex) & 0xff))
+			break;
+
+		handled = handle_test_mode(mtu, setup);
+		break;
+	default:
+		handled = -EINVAL;
+		break;
+	}
+	return handled;
+}
+
+static int ep0_handle_feature(struct mtu3 *mtu,
+		struct usb_ctrlrequest *setup, bool set)
+{
+	struct mtu3_ep *mep;
+	int handled = -EINVAL;
+	int is_in;
+	u16 value;
+	u16 index;
+	u8 epnum;
+
+	value = le16_to_cpu(setup->wValue);
+	index = le16_to_cpu(setup->wIndex);
+
+	switch (setup->bRequestType & USB_RECIP_MASK) {
+	case USB_RECIP_DEVICE:
+		handled = ep0_handle_feature_dev(mtu, setup, set);
+		break;
+	case USB_RECIP_ENDPOINT:
+		epnum = index & USB_ENDPOINT_NUMBER_MASK;
+		if (epnum == 0 || epnum >= mtu->num_eps ||
+			value != USB_ENDPOINT_HALT)
+			break;
+
+		is_in = index & USB_DIR_IN;
+		mep = (is_in ? mtu->in_eps : mtu->out_eps) + epnum;
+		if (!mep->desc)
+			break;
+
+		handled = 1;
+		/* ignore request if endpoint is wedged */
+		if (mep->wedged)
+			break;
+
+		mtu3_ep_stall_set(mep, set);
+		break;
+	default:
+		/* class, vendor, etc ... delegate */
+		handled = 0;
+		break;
+	}
+	return handled;
+}
+
+/*
+ * handle all control requests can be handled
+ * returns:
+ *	negative errno - error happened
+ *	zero - need delegate SETUP to gadget driver
+ *	positive - already handled
+ */
+static int handle_standard_request(struct mtu3 *mtu,
+			  struct usb_ctrlrequest *setup)
+{
+	void __iomem *mbase = mtu->mac_base;
+	enum usb_device_state state = mtu->g.state;
+	int handled = -EINVAL;
+	u32 dev_conf;
+	u16 value;
+
+	value = le16_to_cpu(setup->wValue);
+
+	/* the gadget driver handles everything except what we must handle */
+	switch (setup->bRequest) {
+	case USB_REQ_SET_ADDRESS:
+		/* change it after the status stage */
+		mtu->address = (u8) (value & 0x7f);
+		dev_dbg(mtu->dev, "set address to 0x%x\n", mtu->address);
+
+		dev_conf = mtu3_readl(mbase, U3D_DEVICE_CONF);
+		dev_conf &= ~DEV_ADDR_MSK;
+		dev_conf |= DEV_ADDR(mtu->address);
+		mtu3_writel(mbase, U3D_DEVICE_CONF, dev_conf);
+
+		if (mtu->address)
+			usb_gadget_set_state(&mtu->g, USB_STATE_ADDRESS);
+		else
+			usb_gadget_set_state(&mtu->g, USB_STATE_DEFAULT);
+
+		handled = 1;
+		break;
+	case USB_REQ_SET_CONFIGURATION:
+		if (state == USB_STATE_ADDRESS) {
+			usb_gadget_set_state(&mtu->g,
+					USB_STATE_CONFIGURED);
+		} else if (state == USB_STATE_CONFIGURED) {
+			/*
+			 * USB2 spec sec 9.4.7, if wValue is 0 then dev
+			 * is moved to addressed state
+			 */
+			if (!value)
+				usb_gadget_set_state(&mtu->g,
+						USB_STATE_ADDRESS);
+		}
+		handled = 0;
+		break;
+	case USB_REQ_CLEAR_FEATURE:
+		handled = ep0_handle_feature(mtu, setup, 0);
+		break;
+	case USB_REQ_SET_FEATURE:
+		handled = ep0_handle_feature(mtu, setup, 1);
+		break;
+	case USB_REQ_GET_STATUS:
+		handled = ep0_get_status(mtu, setup);
+		break;
+	case USB_REQ_SET_ISOCH_DELAY:
+		handled = 1;
+		break;
+	default:
+		/* delegate SET_CONFIGURATION, etc */
+		handled = 0;
+	}
+
+	return handled;
+}
+
+/* receive an data packet (OUT) */
+static void ep0_rx_state(struct mtu3 *mtu)
+{
+	struct mtu3_request *mreq;
+	struct usb_request *req;
+	void __iomem *mbase = mtu->mac_base;
+	u32 maxp;
+	u32 csr;
+	u16 count = 0;
+
+	dev_dbg(mtu->dev, "%s\n", __func__);
+
+	csr = mtu3_readl(mbase, U3D_EP0CSR) & EP0_W1C_BITS;
+	mreq = next_ep0_request(mtu);
+	req = &mreq->request;
+
+	/* read packet and ack; or stall because of gadget driver bug */
+	if (req) {
+		void *buf = req->buf + req->actual;
+		unsigned int len = req->length - req->actual;
+
+		/* read the buffer */
+		count = mtu3_readl(mbase, U3D_RXCOUNT0);
+		if (count > len) {
+			req->status = -EOVERFLOW;
+			count = len;
+		}
+		ep0_read_fifo(mtu->ep0, buf, count);
+		req->actual += count;
+		csr |= EP0_RXPKTRDY;
+
+		maxp = mtu->g.ep0->maxpacket;
+		if (count < maxp || req->actual == req->length) {
+			mtu->ep0_state = MU3D_EP0_STATE_SETUP;
+			dev_dbg(mtu->dev, "ep0 state: %s\n",
+				decode_ep0_state(mtu));
+
+			csr |= EP0_DATAEND;
+		} else {
+			req = NULL;
+		}
+	} else {
+		csr |= EP0_RXPKTRDY | EP0_SENDSTALL;
+		dev_dbg(mtu->dev, "%s: SENDSTALL\n", __func__);
+	}
+
+	mtu3_writel(mbase, U3D_EP0CSR, csr);
+
+	/* give back the request if have received all data */
+	if (req)
+		ep0_req_giveback(mtu, req);
+
+}
+
+/* transmitting to the host (IN) */
+static void ep0_tx_state(struct mtu3 *mtu)
+{
+	struct mtu3_request *mreq = next_ep0_request(mtu);
+	struct usb_request *req;
+	u32 csr;
+	u8 *src;
+	u8 count;
+	u32 maxp;
+
+	dev_dbg(mtu->dev, "%s\n", __func__);
+
+	if (!mreq)
+		return;
+
+	maxp = mtu->g.ep0->maxpacket;
+	req = &mreq->request;
+
+	/* load the data */
+	src = (u8 *)req->buf + req->actual;
+	count = min(maxp, req->length - req->actual);
+	if (count)
+		ep0_write_fifo(mtu->ep0, src, count);
+
+	dev_dbg(mtu->dev, "%s act=%d, len=%d, cnt=%d, maxp=%d zero=%d\n",
+		 __func__, req->actual, req->length, count, maxp, req->zero);
+
+	req->actual += count;
+
+	if ((count < maxp)
+		|| ((req->actual == req->length) && !req->zero))
+		mtu->ep0_state = MU3D_EP0_STATE_TX_END;
+
+	/* send it out, triggering a "txpktrdy cleared" irq */
+	csr = mtu3_readl(mtu->mac_base, U3D_EP0CSR) & EP0_W1C_BITS;
+	mtu3_writel(mtu->mac_base, U3D_EP0CSR, csr | EP0_TXPKTRDY);
+
+	dev_dbg(mtu->dev, "%s ep0csr=0x%x\n", __func__,
+		mtu3_readl(mtu->mac_base, U3D_EP0CSR));
+}
+
+static void ep0_read_setup(struct mtu3 *mtu, struct usb_ctrlrequest *setup)
+{
+	struct mtu3_request *mreq;
+	u32 count;
+	u32 csr;
+
+	csr = mtu3_readl(mtu->mac_base, U3D_EP0CSR) & EP0_W1C_BITS;
+	count = mtu3_readl(mtu->mac_base, U3D_RXCOUNT0);
+
+	ep0_read_fifo(mtu->ep0, (u8 *)setup, count);
+
+	dev_dbg(mtu->dev, "SETUP req%02x.%02x v%04x i%04x l%04x\n",
+		 setup->bRequestType, setup->bRequest,
+		 le16_to_cpu(setup->wValue), le16_to_cpu(setup->wIndex),
+		 le16_to_cpu(setup->wLength));
+
+	/* clean up any leftover transfers */
+	mreq = next_ep0_request(mtu);
+	if (mreq)
+		ep0_req_giveback(mtu, &mreq->request);
+
+	if (le16_to_cpu(setup->wLength) == 0) {
+		;	/* no data stage, nothing to do */
+	} else if (setup->bRequestType & USB_DIR_IN) {
+		mtu3_writel(mtu->mac_base, U3D_EP0CSR,
+			csr | EP0_SETUPPKTRDY | EP0_DPHTX);
+		mtu->ep0_state = MU3D_EP0_STATE_TX;
+	} else {
+		mtu3_writel(mtu->mac_base, U3D_EP0CSR,
+			(csr | EP0_SETUPPKTRDY) & (~EP0_DPHTX));
+		mtu->ep0_state = MU3D_EP0_STATE_RX;
+	}
+}
+
+static int ep0_handle_setup(struct mtu3 *mtu)
+__releases(mtu->lock)
+__acquires(mtu->lock)
+{
+	struct usb_ctrlrequest setup;
+	struct mtu3_request *mreq;
+	void __iomem *mbase = mtu->mac_base;
+	int handled = 0;
+
+	ep0_read_setup(mtu, &setup);
+
+	if ((setup.bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD)
+		handled = handle_standard_request(mtu, &setup);
+
+	dev_dbg(mtu->dev, "handled %d, ep0_state: %s\n",
+		 handled, decode_ep0_state(mtu));
+
+	if (handled < 0)
+		goto stall;
+	else if (handled > 0)
+		goto finish;
+
+	handled = forward_to_driver(mtu, &setup);
+	if (handled < 0) {
+stall:
+		dev_dbg(mtu->dev, "%s stall (%d)\n", __func__, handled);
+
+		ep0_stall_set(mtu->ep0, true,
+			le16_to_cpu(setup.wLength) ? 0 : EP0_SETUPPKTRDY);
+
+		return 0;
+	}
+
+finish:
+	if (mtu->test_mode) {
+		;	/* nothing to do */
+	} else if (le16_to_cpu(setup.wLength) == 0) { /* no data stage */
+
+		mtu3_writel(mbase, U3D_EP0CSR,
+			(mtu3_readl(mbase, U3D_EP0CSR) & EP0_W1C_BITS)
+			| EP0_SETUPPKTRDY | EP0_DATAEND);
+
+		/* complete zlp request directly */
+		mreq = next_ep0_request(mtu);
+		if (mreq && !mreq->request.length)
+			ep0_req_giveback(mtu, &mreq->request);
+	}
+
+	return 0;
+}
+
+irqreturn_t mtu3_ep0_isr(struct mtu3 *mtu)
+{
+	void __iomem *mbase = mtu->mac_base;
+	struct mtu3_request *mreq;
+	u32 int_status;
+	irqreturn_t ret = IRQ_NONE;
+	u32 csr;
+	u32 len;
+
+	int_status = mtu3_readl(mbase, U3D_EPISR);
+	int_status &= mtu3_readl(mbase, U3D_EPIER);
+	mtu3_writel(mbase, U3D_EPISR, int_status); /* W1C */
+
+	/* only handle ep0's */
+	if (!(int_status & EP0ISR))
+		return IRQ_NONE;
+
+	csr = mtu3_readl(mbase, U3D_EP0CSR);
+
+	dev_dbg(mtu->dev, "%s csr=0x%x\n", __func__, csr);
+
+	/* we sent a stall.. need to clear it now.. */
+	if (csr & EP0_SENTSTALL) {
+		ep0_stall_set(mtu->ep0, false, 0);
+		csr = mtu3_readl(mbase, U3D_EP0CSR);
+		ret = IRQ_HANDLED;
+	}
+	dev_dbg(mtu->dev, "ep0_state: %s\n", decode_ep0_state(mtu));
+
+	switch (mtu->ep0_state) {
+	case MU3D_EP0_STATE_TX:
+		/* irq on clearing txpktrdy */
+		if ((csr & EP0_FIFOFULL) == 0) {
+			ep0_tx_state(mtu);
+			ret = IRQ_HANDLED;
+		}
+		break;
+	case MU3D_EP0_STATE_RX:
+		/* irq on set rxpktrdy */
+		if (csr & EP0_RXPKTRDY) {
+			ep0_rx_state(mtu);
+			ret = IRQ_HANDLED;
+		}
+		break;
+	case MU3D_EP0_STATE_TX_END:
+		mtu3_writel(mbase, U3D_EP0CSR,
+			(csr & EP0_W1C_BITS) | EP0_DATAEND);
+
+		mreq = next_ep0_request(mtu);
+		if (mreq)
+			ep0_req_giveback(mtu, &mreq->request);
+
+		mtu->ep0_state = MU3D_EP0_STATE_SETUP;
+		ret = IRQ_HANDLED;
+		dev_dbg(mtu->dev, "ep0_state: %s\n", decode_ep0_state(mtu));
+		break;
+	case MU3D_EP0_STATE_SETUP:
+		if (!(csr & EP0_SETUPPKTRDY))
+			break;
+
+		len = mtu3_readl(mbase, U3D_RXCOUNT0);
+		if (len != 8) {
+			dev_err(mtu->dev, "SETUP packet len %d != 8 ?\n", len);
+			break;
+		}
+
+		ep0_handle_setup(mtu);
+		ret = IRQ_HANDLED;
+		break;
+	default:
+		/* can't happen */
+		ep0_stall_set(mtu->ep0, true, 0);
+		WARN_ON(1);
+		break;
+	}
+
+	return ret;
+}
+
+
+static int mtu3_ep0_enable(struct usb_ep *ep,
+	const struct usb_endpoint_descriptor *desc)
+{
+	/* always enabled */
+	return -EINVAL;
+}
+
+static int mtu3_ep0_disable(struct usb_ep *ep)
+{
+	/* always enabled */
+	return -EINVAL;
+}
+
+static int ep0_queue(struct mtu3_ep *mep, struct mtu3_request *mreq)
+{
+	struct mtu3 *mtu = mep->mtu;
+
+	mreq->mtu = mtu;
+	mreq->request.actual = 0;
+	mreq->request.status = -EINPROGRESS;
+
+	dev_dbg(mtu->dev, "%s %s (ep0_state: %s), len#%d\n", __func__,
+		mep->name, decode_ep0_state(mtu), mreq->request.length);
+
+	if (!list_empty(&mep->req_list))
+		return -EBUSY;
+
+	switch (mtu->ep0_state) {
+	case MU3D_EP0_STATE_SETUP:
+	case MU3D_EP0_STATE_RX:	/* control-OUT data */
+	case MU3D_EP0_STATE_TX:	/* control-IN data */
+		break;
+	default:
+		dev_err(mtu->dev, "%s, error in ep0 state %s\n", __func__,
+			decode_ep0_state(mtu));
+		return -EINVAL;
+	}
+
+	list_add_tail(&mreq->list, &mep->req_list);
+
+	/* sequence #1, IN ... start writing the data */
+	if (mtu->ep0_state == MU3D_EP0_STATE_TX)
+		ep0_tx_state(mtu);
+
+	return 0;
+}
+
+static int mtu3_ep0_queue(struct usb_ep *ep,
+	struct usb_request *req, gfp_t gfp)
+{
+	struct mtu3_ep *mep;
+	struct mtu3_request *mreq;
+	struct mtu3 *mtu;
+	unsigned long flags;
+	int ret = 0;
+
+	if (!ep || !req)
+		return -EINVAL;
+
+	mep = to_mtu3_ep(ep);
+	mtu = mep->mtu;
+	mreq = to_mtu3_request(req);
+
+	spin_lock_irqsave(&mtu->lock, flags);
+	ret = ep0_queue(mep, mreq);
+	spin_unlock_irqrestore(&mtu->lock, flags);
+	return ret;
+}
+
+static int mtu3_ep0_dequeue(struct usb_ep *ep, struct usb_request *req)
+{
+	/* we just won't support this */
+	return -EINVAL;
+}
+
+static int mtu3_ep0_halt(struct usb_ep *ep, int value)
+{
+	struct mtu3_ep *mep;
+	struct mtu3 *mtu;
+	unsigned long flags;
+	int ret = 0;
+
+	if (!ep || !value)
+		return -EINVAL;
+
+	mep = to_mtu3_ep(ep);
+	mtu = mep->mtu;
+
+	dev_dbg(mtu->dev, "%s\n", __func__);
+
+	spin_lock_irqsave(&mtu->lock, flags);
+
+	if (!list_empty(&mep->req_list)) {
+		ret = -EBUSY;
+		goto cleanup;
+	}
+
+	switch (mtu->ep0_state) {
+	/*
+	 * stalls are usually issued after parsing SETUP packet, either
+	 * directly in irq context from setup() or else later.
+	 */
+	case MU3D_EP0_STATE_TX:
+	case MU3D_EP0_STATE_TX_END:
+	case MU3D_EP0_STATE_RX:
+	case MU3D_EP0_STATE_SETUP:
+		ep0_stall_set(mtu->ep0, true, 0);
+		break;
+	default:
+		dev_dbg(mtu->dev, "ep0 can't halt in state %s\n",
+			decode_ep0_state(mtu));
+		ret = -EINVAL;
+	}
+
+cleanup:
+	spin_unlock_irqrestore(&mtu->lock, flags);
+	return ret;
+}
+
+const struct usb_ep_ops mtu3_ep0_ops = {
+	.enable = mtu3_ep0_enable,
+	.disable = mtu3_ep0_disable,
+	.alloc_request = mtu3_alloc_request,
+	.free_request = mtu3_free_request,
+	.queue = mtu3_ep0_queue,
+	.dequeue = mtu3_ep0_dequeue,
+	.set_halt = mtu3_ep0_halt,
+};