usb: chipidea: brush up structure definitions

[mirror_ubuntu-hirsute-kernel.git] / drivers / usb / chipidea / udc.c

/*
 * udc.h - ChipIdea UDC driver
 *
 * Copyright (C) 2008 Chipidea - MIPS Technologies, Inc. All rights reserved.
 *
 * Author: David Lopo
 *
 * 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.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/otg.h>
#include <linux/usb/chipidea.h>

#include "ci.h"
#include "udc.h"
#include "bits.h"
#include "debug.h"

/* control endpoint description */
static const struct usb_endpoint_descriptor
ctrl_endpt_out_desc = {
	.bLength         = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,

	.bEndpointAddress = USB_DIR_OUT,
	.bmAttributes    = USB_ENDPOINT_XFER_CONTROL,
	.wMaxPacketSize  = cpu_to_le16(CTRL_PAYLOAD_MAX),
};

static const struct usb_endpoint_descriptor
ctrl_endpt_in_desc = {
	.bLength         = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,

	.bEndpointAddress = USB_DIR_IN,
	.bmAttributes    = USB_ENDPOINT_XFER_CONTROL,
	.wMaxPacketSize  = cpu_to_le16(CTRL_PAYLOAD_MAX),
};

/**
 * hw_ep_bit: calculates the bit number
 * @num: endpoint number
 * @dir: endpoint direction
 *
 * This function returns bit number
 */
static inline int hw_ep_bit(int num, int dir)
{
	return num + (dir ? 16 : 0);
}

static inline int ep_to_bit(struct ci13xxx *udc, int n)
{
	int fill = 16 - udc->hw_ep_max / 2;

	if (n >= udc->hw_ep_max / 2)
		n += fill;

	return n;
}

/**
 * hw_device_state: enables/disables interrupts & starts/stops device (execute
 *                  without interruption)
 * @dma: 0 => disable, !0 => enable and set dma engine
 *
 * This function returns an error code
 */
static int hw_device_state(struct ci13xxx *udc, u32 dma)
{
	if (dma) {
		hw_write(udc, OP_ENDPTLISTADDR, ~0, dma);
		/* interrupt, error, port change, reset, sleep/suspend */
		hw_write(udc, OP_USBINTR, ~0,
			     USBi_UI|USBi_UEI|USBi_PCI|USBi_URI|USBi_SLI);
		hw_write(udc, OP_USBCMD, USBCMD_RS, USBCMD_RS);
	} else {
		hw_write(udc, OP_USBCMD, USBCMD_RS, 0);
		hw_write(udc, OP_USBINTR, ~0, 0);
	}
	return 0;
}

/**
 * hw_ep_flush: flush endpoint fifo (execute without interruption)
 * @num: endpoint number
 * @dir: endpoint direction
 *
 * This function returns an error code
 */
static int hw_ep_flush(struct ci13xxx *udc, int num, int dir)
{
	int n = hw_ep_bit(num, dir);

	do {
		/* flush any pending transfer */
		hw_write(udc, OP_ENDPTFLUSH, BIT(n), BIT(n));
		while (hw_read(udc, OP_ENDPTFLUSH, BIT(n)))
			cpu_relax();
	} while (hw_read(udc, OP_ENDPTSTAT, BIT(n)));

	return 0;
}

/**
 * hw_ep_disable: disables endpoint (execute without interruption)
 * @num: endpoint number
 * @dir: endpoint direction
 *
 * This function returns an error code
 */
static int hw_ep_disable(struct ci13xxx *udc, int num, int dir)
{
	hw_ep_flush(udc, num, dir);
	hw_write(udc, OP_ENDPTCTRL + num,
		 dir ? ENDPTCTRL_TXE : ENDPTCTRL_RXE, 0);
	return 0;
}

/**
 * hw_ep_enable: enables endpoint (execute without interruption)
 * @num:  endpoint number
 * @dir:  endpoint direction
 * @type: endpoint type
 *
 * This function returns an error code
 */
static int hw_ep_enable(struct ci13xxx *udc, int num, int dir, int type)
{
	u32 mask, data;

	if (dir) {
		mask  = ENDPTCTRL_TXT;  /* type    */
		data  = type << ffs_nr(mask);

		mask |= ENDPTCTRL_TXS;  /* unstall */
		mask |= ENDPTCTRL_TXR;  /* reset data toggle */
		data |= ENDPTCTRL_TXR;
		mask |= ENDPTCTRL_TXE;  /* enable  */
		data |= ENDPTCTRL_TXE;
	} else {
		mask  = ENDPTCTRL_RXT;  /* type    */
		data  = type << ffs_nr(mask);

		mask |= ENDPTCTRL_RXS;  /* unstall */
		mask |= ENDPTCTRL_RXR;  /* reset data toggle */
		data |= ENDPTCTRL_RXR;
		mask |= ENDPTCTRL_RXE;  /* enable  */
		data |= ENDPTCTRL_RXE;
	}
	hw_write(udc, OP_ENDPTCTRL + num, mask, data);
	return 0;
}

/**
 * hw_ep_get_halt: return endpoint halt status
 * @num: endpoint number
 * @dir: endpoint direction
 *
 * This function returns 1 if endpoint halted
 */
static int hw_ep_get_halt(struct ci13xxx *udc, int num, int dir)
{
	u32 mask = dir ? ENDPTCTRL_TXS : ENDPTCTRL_RXS;

	return hw_read(udc, OP_ENDPTCTRL + num, mask) ? 1 : 0;
}

/**
 * hw_test_and_clear_setup_status: test & clear setup status (execute without
 *                                 interruption)
 * @n: endpoint number
 *
 * This function returns setup status
 */
static int hw_test_and_clear_setup_status(struct ci13xxx *udc, int n)
{
	n = ep_to_bit(udc, n);
	return hw_test_and_clear(udc, OP_ENDPTSETUPSTAT, BIT(n));
}

/**
 * hw_ep_prime: primes endpoint (execute without interruption)
 * @num:     endpoint number
 * @dir:     endpoint direction
 * @is_ctrl: true if control endpoint
 *
 * This function returns an error code
 */
static int hw_ep_prime(struct ci13xxx *udc, int num, int dir, int is_ctrl)
{
	int n = hw_ep_bit(num, dir);

	if (is_ctrl && dir == RX && hw_read(udc, OP_ENDPTSETUPSTAT, BIT(num)))
		return -EAGAIN;

	hw_write(udc, OP_ENDPTPRIME, BIT(n), BIT(n));

	while (hw_read(udc, OP_ENDPTPRIME, BIT(n)))
		cpu_relax();
	if (is_ctrl && dir == RX && hw_read(udc, OP_ENDPTSETUPSTAT, BIT(num)))
		return -EAGAIN;

	/* status shoult be tested according with manual but it doesn't work */
	return 0;
}

/**
 * hw_ep_set_halt: configures ep halt & resets data toggle after clear (execute
 *                 without interruption)
 * @num:   endpoint number
 * @dir:   endpoint direction
 * @value: true => stall, false => unstall
 *
 * This function returns an error code
 */
static int hw_ep_set_halt(struct ci13xxx *udc, int num, int dir, int value)
{
	if (value != 0 && value != 1)
		return -EINVAL;

	do {
		enum ci13xxx_regs reg = OP_ENDPTCTRL + num;
		u32 mask_xs = dir ? ENDPTCTRL_TXS : ENDPTCTRL_RXS;
		u32 mask_xr = dir ? ENDPTCTRL_TXR : ENDPTCTRL_RXR;

		/* data toggle - reserved for EP0 but it's in ESS */
		hw_write(udc, reg, mask_xs|mask_xr,
			  value ? mask_xs : mask_xr);
	} while (value != hw_ep_get_halt(udc, num, dir));

	return 0;
}

/**
 * hw_is_port_high_speed: test if port is high speed
 *
 * This function returns true if high speed port
 */
static int hw_port_is_high_speed(struct ci13xxx *udc)
{
	return udc->hw_bank.lpm ? hw_read(udc, OP_DEVLC, DEVLC_PSPD) :
		hw_read(udc, OP_PORTSC, PORTSC_HSP);
}

/**
 * hw_read_intr_enable: returns interrupt enable register
 *
 * This function returns register data
 */
static u32 hw_read_intr_enable(struct ci13xxx *udc)
{
	return hw_read(udc, OP_USBINTR, ~0);
}

/**
 * hw_read_intr_status: returns interrupt status register
 *
 * This function returns register data
 */
static u32 hw_read_intr_status(struct ci13xxx *udc)
{
	return hw_read(udc, OP_USBSTS, ~0);
}

/**
 * hw_test_and_clear_complete: test & clear complete status (execute without
 *                             interruption)
 * @n: endpoint number
 *
 * This function returns complete status
 */
static int hw_test_and_clear_complete(struct ci13xxx *udc, int n)
{
	n = ep_to_bit(udc, n);
	return hw_test_and_clear(udc, OP_ENDPTCOMPLETE, BIT(n));
}

/**
 * hw_test_and_clear_intr_active: test & clear active interrupts (execute
 *                                without interruption)
 *
 * This function returns active interrutps
 */
static u32 hw_test_and_clear_intr_active(struct ci13xxx *udc)
{
	u32 reg = hw_read_intr_status(udc) & hw_read_intr_enable(udc);

	hw_write(udc, OP_USBSTS, ~0, reg);
	return reg;
}

/**
 * hw_test_and_clear_setup_guard: test & clear setup guard (execute without
 *                                interruption)
 *
 * This function returns guard value
 */
static int hw_test_and_clear_setup_guard(struct ci13xxx *udc)
{
	return hw_test_and_write(udc, OP_USBCMD, USBCMD_SUTW, 0);
}

/**
 * hw_test_and_set_setup_guard: test & set setup guard (execute without
 *                              interruption)
 *
 * This function returns guard value
 */
static int hw_test_and_set_setup_guard(struct ci13xxx *udc)
{
	return hw_test_and_write(udc, OP_USBCMD, USBCMD_SUTW, USBCMD_SUTW);
}

/**
 * hw_usb_set_address: configures USB address (execute without interruption)
 * @value: new USB address
 *
 * This function explicitly sets the address, without the "USBADRA" (advance)
 * feature, which is not supported by older versions of the controller.
 */
static void hw_usb_set_address(struct ci13xxx *udc, u8 value)
{
	hw_write(udc, OP_DEVICEADDR, DEVICEADDR_USBADR,
		 value << ffs_nr(DEVICEADDR_USBADR));
}

/**
 * hw_usb_reset: restart device after a bus reset (execute without
 *               interruption)
 *
 * This function returns an error code
 */
static int hw_usb_reset(struct ci13xxx *udc)
{
	hw_usb_set_address(udc, 0);

	/* ESS flushes only at end?!? */
	hw_write(udc, OP_ENDPTFLUSH,    ~0, ~0);

	/* clear setup token semaphores */
	hw_write(udc, OP_ENDPTSETUPSTAT, 0,  0);

	/* clear complete status */
	hw_write(udc, OP_ENDPTCOMPLETE,  0,  0);

	/* wait until all bits cleared */
	while (hw_read(udc, OP_ENDPTPRIME, ~0))
		udelay(10);             /* not RTOS friendly */

	/* reset all endpoints ? */

	/* reset internal status and wait for further instructions
	   no need to verify the port reset status (ESS does it) */

	return 0;
}

/******************************************************************************
 * UTIL block
 *****************************************************************************/
/**
 * _usb_addr: calculates endpoint address from direction & number
 * @ep:  endpoint
 */
static inline u8 _usb_addr(struct ci13xxx_ep *ep)
{
	return ((ep->dir == TX) ? USB_ENDPOINT_DIR_MASK : 0) | ep->num;
}

/**
 * _hardware_queue: configures a request at hardware level
 * @gadget: gadget
 * @mEp:    endpoint
 *
 * This function returns an error code
 */
static int _hardware_enqueue(struct ci13xxx_ep *mEp, struct ci13xxx_req *mReq)
{
	struct ci13xxx *udc = mEp->udc;
	unsigned i;
	int ret = 0;
	unsigned length = mReq->req.length;

	/* don't queue twice */
	if (mReq->req.status == -EALREADY)
		return -EALREADY;

	mReq->req.status = -EALREADY;
	if (length && mReq->req.dma == DMA_ADDR_INVALID) {
		mReq->req.dma = \
			dma_map_single(mEp->device, mReq->req.buf,
				       length, mEp->dir ? DMA_TO_DEVICE :
				       DMA_FROM_DEVICE);
		if (mReq->req.dma == 0)
			return -ENOMEM;

		mReq->map = 1;
	}

	if (mReq->req.zero && length && (length % mEp->ep.maxpacket == 0)) {
		mReq->zptr = dma_pool_alloc(mEp->td_pool, GFP_ATOMIC,
					   &mReq->zdma);
		if (mReq->zptr == NULL) {
			if (mReq->map) {
				dma_unmap_single(mEp->device, mReq->req.dma,
					length, mEp->dir ? DMA_TO_DEVICE :
					DMA_FROM_DEVICE);
				mReq->req.dma = DMA_ADDR_INVALID;
				mReq->map     = 0;
			}
			return -ENOMEM;
		}
		memset(mReq->zptr, 0, sizeof(*mReq->zptr));
		mReq->zptr->next    = TD_TERMINATE;
		mReq->zptr->token   = TD_STATUS_ACTIVE;
		if (!mReq->req.no_interrupt)
			mReq->zptr->token   |= TD_IOC;
	}
	/*
	 * TD configuration
	 * TODO - handle requests which spawns into several TDs
	 */
	memset(mReq->ptr, 0, sizeof(*mReq->ptr));
	mReq->ptr->token    = length << ffs_nr(TD_TOTAL_BYTES);
	mReq->ptr->token   &= TD_TOTAL_BYTES;
	mReq->ptr->token   |= TD_STATUS_ACTIVE;
	if (mReq->zptr) {
		mReq->ptr->next    = mReq->zdma;
	} else {
		mReq->ptr->next    = TD_TERMINATE;
		if (!mReq->req.no_interrupt)
			mReq->ptr->token  |= TD_IOC;
	}
	mReq->ptr->page[0]  = mReq->req.dma;
	for (i = 1; i < 5; i++)
		mReq->ptr->page[i] =
			(mReq->req.dma + i * CI13XXX_PAGE_SIZE) & ~TD_RESERVED_MASK;

	if (!list_empty(&mEp->qh.queue)) {
		struct ci13xxx_req *mReqPrev;
		int n = hw_ep_bit(mEp->num, mEp->dir);
		int tmp_stat;

		mReqPrev = list_entry(mEp->qh.queue.prev,
				struct ci13xxx_req, queue);
		if (mReqPrev->zptr)
			mReqPrev->zptr->next = mReq->dma & TD_ADDR_MASK;
		else
			mReqPrev->ptr->next = mReq->dma & TD_ADDR_MASK;
		wmb();
		if (hw_read(udc, OP_ENDPTPRIME, BIT(n)))
			goto done;
		do {
			hw_write(udc, OP_USBCMD, USBCMD_ATDTW, USBCMD_ATDTW);
			tmp_stat = hw_read(udc, OP_ENDPTSTAT, BIT(n));
		} while (!hw_read(udc, OP_USBCMD, USBCMD_ATDTW));
		hw_write(udc, OP_USBCMD, USBCMD_ATDTW, 0);
		if (tmp_stat)
			goto done;
	}

	/*  QH configuration */
	mEp->qh.ptr->td.next   = mReq->dma;    /* TERMINATE = 0 */
	mEp->qh.ptr->td.token &= ~TD_STATUS;   /* clear status */
	mEp->qh.ptr->cap |=  QH_ZLT;

	wmb();   /* synchronize before ep prime */

	ret = hw_ep_prime(udc, mEp->num, mEp->dir,
			   mEp->type == USB_ENDPOINT_XFER_CONTROL);
done:
	return ret;
}

/**
 * _hardware_dequeue: handles a request at hardware level
 * @gadget: gadget
 * @mEp:    endpoint
 *
 * This function returns an error code
 */
static int _hardware_dequeue(struct ci13xxx_ep *mEp, struct ci13xxx_req *mReq)
{
	if (mReq->req.status != -EALREADY)
		return -EINVAL;

	if ((TD_STATUS_ACTIVE & mReq->ptr->token) != 0)
		return -EBUSY;

	if (mReq->zptr) {
		if ((TD_STATUS_ACTIVE & mReq->zptr->token) != 0)
			return -EBUSY;
		dma_pool_free(mEp->td_pool, mReq->zptr, mReq->zdma);
		mReq->zptr = NULL;
	}

	mReq->req.status = 0;

	if (mReq->map) {
		dma_unmap_single(mEp->device, mReq->req.dma, mReq->req.length,
				 mEp->dir ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
		mReq->req.dma = DMA_ADDR_INVALID;
		mReq->map     = 0;
	}

	mReq->req.status = mReq->ptr->token & TD_STATUS;
	if ((TD_STATUS_HALTED & mReq->req.status) != 0)
		mReq->req.status = -1;
	else if ((TD_STATUS_DT_ERR & mReq->req.status) != 0)
		mReq->req.status = -1;
	else if ((TD_STATUS_TR_ERR & mReq->req.status) != 0)
		mReq->req.status = -1;

	mReq->req.actual   = mReq->ptr->token & TD_TOTAL_BYTES;
	mReq->req.actual >>= ffs_nr(TD_TOTAL_BYTES);
	mReq->req.actual   = mReq->req.length - mReq->req.actual;
	mReq->req.actual   = mReq->req.status ? 0 : mReq->req.actual;

	return mReq->req.actual;
}

/**
 * _ep_nuke: dequeues all endpoint requests
 * @mEp: endpoint
 *
 * This function returns an error code
 * Caller must hold lock
 */
static int _ep_nuke(struct ci13xxx_ep *mEp)
__releases(mEp->lock)
__acquires(mEp->lock)
{
	if (mEp == NULL)
		return -EINVAL;

	hw_ep_flush(mEp->udc, mEp->num, mEp->dir);

	while (!list_empty(&mEp->qh.queue)) {

		/* pop oldest request */
		struct ci13xxx_req *mReq = \
			list_entry(mEp->qh.queue.next,
				   struct ci13xxx_req, queue);
		list_del_init(&mReq->queue);
		mReq->req.status = -ESHUTDOWN;

		if (mReq->req.complete != NULL) {
			spin_unlock(mEp->lock);
			mReq->req.complete(&mEp->ep, &mReq->req);
			spin_lock(mEp->lock);
		}
	}
	return 0;
}

/**
 * _gadget_stop_activity: stops all USB activity, flushes & disables all endpts
 * @gadget: gadget
 *
 * This function returns an error code
 */
static int _gadget_stop_activity(struct usb_gadget *gadget)
{
	struct usb_ep *ep;
	struct ci13xxx    *udc = container_of(gadget, struct ci13xxx, gadget);
	unsigned long flags;

	if (gadget == NULL)
		return -EINVAL;

	spin_lock_irqsave(&udc->lock, flags);
	udc->gadget.speed = USB_SPEED_UNKNOWN;
	udc->remote_wakeup = 0;
	udc->suspended = 0;
	spin_unlock_irqrestore(&udc->lock, flags);

	/* flush all endpoints */
	gadget_for_each_ep(ep, gadget) {
		usb_ep_fifo_flush(ep);
	}
	usb_ep_fifo_flush(&udc->ep0out->ep);
	usb_ep_fifo_flush(&udc->ep0in->ep);

	if (udc->driver)
		udc->driver->disconnect(gadget);

	/* make sure to disable all endpoints */
	gadget_for_each_ep(ep, gadget) {
		usb_ep_disable(ep);
	}

	if (udc->status != NULL) {
		usb_ep_free_request(&udc->ep0in->ep, udc->status);
		udc->status = NULL;
	}

	return 0;
}

/******************************************************************************
 * ISR block
 *****************************************************************************/
/**
 * isr_reset_handler: USB reset interrupt handler
 * @udc: UDC device
 *
 * This function resets USB engine after a bus reset occurred
 */
static void isr_reset_handler(struct ci13xxx *udc)
__releases(udc->lock)
__acquires(udc->lock)
{
	int retval;

	dbg_event(0xFF, "BUS RST", 0);

	spin_unlock(&udc->lock);
	retval = _gadget_stop_activity(&udc->gadget);
	if (retval)
		goto done;

	retval = hw_usb_reset(udc);
	if (retval)
		goto done;

	udc->status = usb_ep_alloc_request(&udc->ep0in->ep, GFP_ATOMIC);
	if (udc->status == NULL)
		retval = -ENOMEM;

	spin_lock(&udc->lock);

 done:
	if (retval)
		dev_err(udc->dev, "error: %i\n", retval);
}

/**
 * isr_get_status_complete: get_status request complete function
 * @ep:  endpoint
 * @req: request handled
 *
 * Caller must release lock
 */
static void isr_get_status_complete(struct usb_ep *ep, struct usb_request *req)
{
	if (ep == NULL || req == NULL)
		return;

	kfree(req->buf);
	usb_ep_free_request(ep, req);
}

/**
 * isr_get_status_response: get_status request response
 * @udc: udc struct
 * @setup: setup request packet
 *
 * This function returns an error code
 */
static int isr_get_status_response(struct ci13xxx *udc,
				   struct usb_ctrlrequest *setup)
__releases(mEp->lock)
__acquires(mEp->lock)
{
	struct ci13xxx_ep *mEp = udc->ep0in;
	struct usb_request *req = NULL;
	gfp_t gfp_flags = GFP_ATOMIC;
	int dir, num, retval;

	if (mEp == NULL || setup == NULL)
		return -EINVAL;

	spin_unlock(mEp->lock);
	req = usb_ep_alloc_request(&mEp->ep, gfp_flags);
	spin_lock(mEp->lock);
	if (req == NULL)
		return -ENOMEM;

	req->complete = isr_get_status_complete;
	req->length   = 2;
	req->buf      = kzalloc(req->length, gfp_flags);
	if (req->buf == NULL) {
		retval = -ENOMEM;
		goto err_free_req;
	}

	if ((setup->bRequestType & USB_RECIP_MASK) == USB_RECIP_DEVICE) {
		/* Assume that device is bus powered for now. */
		*(u16 *)req->buf = udc->remote_wakeup << 1;
		retval = 0;
	} else if ((setup->bRequestType & USB_RECIP_MASK) \
		   == USB_RECIP_ENDPOINT) {
		dir = (le16_to_cpu(setup->wIndex) & USB_ENDPOINT_DIR_MASK) ?
			TX : RX;
		num =  le16_to_cpu(setup->wIndex) & USB_ENDPOINT_NUMBER_MASK;
		*(u16 *)req->buf = hw_ep_get_halt(udc, num, dir);
	}
	/* else do nothing; reserved for future use */

	spin_unlock(mEp->lock);
	retval = usb_ep_queue(&mEp->ep, req, gfp_flags);
	spin_lock(mEp->lock);
	if (retval)
		goto err_free_buf;

	return 0;

 err_free_buf:
	kfree(req->buf);
 err_free_req:
	spin_unlock(mEp->lock);
	usb_ep_free_request(&mEp->ep, req);
	spin_lock(mEp->lock);
	return retval;
}

/**
 * isr_setup_status_complete: setup_status request complete function
 * @ep:  endpoint
 * @req: request handled
 *
 * Caller must release lock. Put the port in test mode if test mode
 * feature is selected.
 */
static void
isr_setup_status_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct ci13xxx *udc = req->context;
	unsigned long flags;

	if (udc->setaddr) {
		hw_usb_set_address(udc, udc->address);
		udc->setaddr = false;
	}

	spin_lock_irqsave(&udc->lock, flags);
	if (udc->test_mode)
		hw_port_test_set(udc, udc->test_mode);
	spin_unlock_irqrestore(&udc->lock, flags);
}

/**
 * isr_setup_status_phase: queues the status phase of a setup transation
 * @udc: udc struct
 *
 * This function returns an error code
 */
static int isr_setup_status_phase(struct ci13xxx *udc)
__releases(mEp->lock)
__acquires(mEp->lock)
{
	int retval;
	struct ci13xxx_ep *mEp;

	mEp = (udc->ep0_dir == TX) ? udc->ep0out : udc->ep0in;
	udc->status->context = udc;
	udc->status->complete = isr_setup_status_complete;

	spin_unlock(mEp->lock);
	retval = usb_ep_queue(&mEp->ep, udc->status, GFP_ATOMIC);
	spin_lock(mEp->lock);

	return retval;
}

/**
 * isr_tr_complete_low: transaction complete low level handler
 * @mEp: endpoint
 *
 * This function returns an error code
 * Caller must hold lock
 */
static int isr_tr_complete_low(struct ci13xxx_ep *mEp)
__releases(mEp->lock)
__acquires(mEp->lock)
{
	struct ci13xxx_req *mReq, *mReqTemp;
	struct ci13xxx_ep *mEpTemp = mEp;
	int uninitialized_var(retval);

	if (list_empty(&mEp->qh.queue))
		return -EINVAL;

	list_for_each_entry_safe(mReq, mReqTemp, &mEp->qh.queue,
			queue) {
		retval = _hardware_dequeue(mEp, mReq);
		if (retval < 0)
			break;
		list_del_init(&mReq->queue);
		dbg_done(_usb_addr(mEp), mReq->ptr->token, retval);
		if (mReq->req.complete != NULL) {
			spin_unlock(mEp->lock);
			if ((mEp->type == USB_ENDPOINT_XFER_CONTROL) &&
					mReq->req.length)
				mEpTemp = mEp->udc->ep0in;
			mReq->req.complete(&mEpTemp->ep, &mReq->req);
			spin_lock(mEp->lock);
		}
	}

	if (retval == -EBUSY)
		retval = 0;
	if (retval < 0)
		dbg_event(_usb_addr(mEp), "DONE", retval);

	return retval;
}

/**
 * isr_tr_complete_handler: transaction complete interrupt handler
 * @udc: UDC descriptor
 *
 * This function handles traffic events
 */
static void isr_tr_complete_handler(struct ci13xxx *udc)
__releases(udc->lock)
__acquires(udc->lock)
{
	unsigned i;
	u8 tmode = 0;

	for (i = 0; i < udc->hw_ep_max; i++) {
		struct ci13xxx_ep *mEp  = &udc->ci13xxx_ep[i];
		int type, num, dir, err = -EINVAL;
		struct usb_ctrlrequest req;

		if (mEp->ep.desc == NULL)
			continue;   /* not configured */

		if (hw_test_and_clear_complete(udc, i)) {
			err = isr_tr_complete_low(mEp);
			if (mEp->type == USB_ENDPOINT_XFER_CONTROL) {
				if (err > 0)   /* needs status phase */
					err = isr_setup_status_phase(udc);
				if (err < 0) {
					dbg_event(_usb_addr(mEp),
						  "ERROR", err);
					spin_unlock(&udc->lock);
					if (usb_ep_set_halt(&mEp->ep))
						dev_err(udc->dev,
							"error: ep_set_halt\n");
					spin_lock(&udc->lock);
				}
			}
		}

		if (mEp->type != USB_ENDPOINT_XFER_CONTROL ||
		    !hw_test_and_clear_setup_status(udc, i))
			continue;

		if (i != 0) {
			dev_warn(udc->dev, "ctrl traffic at endpoint %d\n", i);
			continue;
		}

		/*
		 * Flush data and handshake transactions of previous
		 * setup packet.
		 */
		_ep_nuke(udc->ep0out);
		_ep_nuke(udc->ep0in);

		/* read_setup_packet */
		do {
			hw_test_and_set_setup_guard(udc);
			memcpy(&req, &mEp->qh.ptr->setup, sizeof(req));
		} while (!hw_test_and_clear_setup_guard(udc));

		type = req.bRequestType;

		udc->ep0_dir = (type & USB_DIR_IN) ? TX : RX;

		dbg_setup(_usb_addr(mEp), &req);

		switch (req.bRequest) {
		case USB_REQ_CLEAR_FEATURE:
			if (type == (USB_DIR_OUT|USB_RECIP_ENDPOINT) &&
					le16_to_cpu(req.wValue) ==
					USB_ENDPOINT_HALT) {
				if (req.wLength != 0)
					break;
				num  = le16_to_cpu(req.wIndex);
				dir = num & USB_ENDPOINT_DIR_MASK;
				num &= USB_ENDPOINT_NUMBER_MASK;
				if (dir) /* TX */
					num += udc->hw_ep_max/2;
				if (!udc->ci13xxx_ep[num].wedge) {
					spin_unlock(&udc->lock);
					err = usb_ep_clear_halt(
						&udc->ci13xxx_ep[num].ep);
					spin_lock(&udc->lock);
					if (err)
						break;
				}
				err = isr_setup_status_phase(udc);
			} else if (type == (USB_DIR_OUT|USB_RECIP_DEVICE) &&
					le16_to_cpu(req.wValue) ==
					USB_DEVICE_REMOTE_WAKEUP) {
				if (req.wLength != 0)
					break;
				udc->remote_wakeup = 0;
				err = isr_setup_status_phase(udc);
			} else {
				goto delegate;
			}
			break;
		case USB_REQ_GET_STATUS:
			if (type != (USB_DIR_IN|USB_RECIP_DEVICE)   &&
			    type != (USB_DIR_IN|USB_RECIP_ENDPOINT) &&
			    type != (USB_DIR_IN|USB_RECIP_INTERFACE))
				goto delegate;
			if (le16_to_cpu(req.wLength) != 2 ||
			    le16_to_cpu(req.wValue)  != 0)
				break;
			err = isr_get_status_response(udc, &req);
			break;
		case USB_REQ_SET_ADDRESS:
			if (type != (USB_DIR_OUT|USB_RECIP_DEVICE))
				goto delegate;
			if (le16_to_cpu(req.wLength) != 0 ||
			    le16_to_cpu(req.wIndex)  != 0)
				break;
			udc->address = (u8)le16_to_cpu(req.wValue);
			udc->setaddr = true;
			err = isr_setup_status_phase(udc);
			break;
		case USB_REQ_SET_FEATURE:
			if (type == (USB_DIR_OUT|USB_RECIP_ENDPOINT) &&
					le16_to_cpu(req.wValue) ==
					USB_ENDPOINT_HALT) {
				if (req.wLength != 0)
					break;
				num  = le16_to_cpu(req.wIndex);
				dir = num & USB_ENDPOINT_DIR_MASK;
				num &= USB_ENDPOINT_NUMBER_MASK;
				if (dir) /* TX */
					num += udc->hw_ep_max/2;

				spin_unlock(&udc->lock);
				err = usb_ep_set_halt(&udc->ci13xxx_ep[num].ep);
				spin_lock(&udc->lock);
				if (!err)
					isr_setup_status_phase(udc);
			} else if (type == (USB_DIR_OUT|USB_RECIP_DEVICE)) {
				if (req.wLength != 0)
					break;
				switch (le16_to_cpu(req.wValue)) {
				case USB_DEVICE_REMOTE_WAKEUP:
					udc->remote_wakeup = 1;
					err = isr_setup_status_phase(udc);
					break;
				case USB_DEVICE_TEST_MODE:
					tmode = le16_to_cpu(req.wIndex) >> 8;
					switch (tmode) {
					case TEST_J:
					case TEST_K:
					case TEST_SE0_NAK:
					case TEST_PACKET:
					case TEST_FORCE_EN:
						udc->test_mode = tmode;
						err = isr_setup_status_phase(
								udc);
						break;
					default:
						break;
					}
				default:
					goto delegate;
				}
			} else {
				goto delegate;
			}
			break;
		default:
delegate:
			if (req.wLength == 0)   /* no data phase */
				udc->ep0_dir = TX;

			spin_unlock(&udc->lock);
			err = udc->driver->setup(&udc->gadget, &req);
			spin_lock(&udc->lock);
			break;
		}

		if (err < 0) {
			dbg_event(_usb_addr(mEp), "ERROR", err);

			spin_unlock(&udc->lock);
			if (usb_ep_set_halt(&mEp->ep))
				dev_err(udc->dev, "error: ep_set_halt\n");
			spin_lock(&udc->lock);
		}
	}
}

/******************************************************************************
 * ENDPT block
 *****************************************************************************/
/**
 * ep_enable: configure endpoint, making it usable
 *
 * Check usb_ep_enable() at "usb_gadget.h" for details
 */
static int ep_enable(struct usb_ep *ep,
		     const struct usb_endpoint_descriptor *desc)
{
	struct ci13xxx_ep *mEp = container_of(ep, struct ci13xxx_ep, ep);
	int retval = 0;
	unsigned long flags;

	if (ep == NULL || desc == NULL)
		return -EINVAL;

	spin_lock_irqsave(mEp->lock, flags);

	/* only internal SW should enable ctrl endpts */

	mEp->ep.desc = desc;

	if (!list_empty(&mEp->qh.queue))
		dev_warn(mEp->udc->dev, "enabling a non-empty endpoint!\n");

	mEp->dir  = usb_endpoint_dir_in(desc) ? TX : RX;
	mEp->num  = usb_endpoint_num(desc);
	mEp->type = usb_endpoint_type(desc);

	mEp->ep.maxpacket = usb_endpoint_maxp(desc);

	dbg_event(_usb_addr(mEp), "ENABLE", 0);

	mEp->qh.ptr->cap = 0;

	if (mEp->type == USB_ENDPOINT_XFER_CONTROL)
		mEp->qh.ptr->cap |=  QH_IOS;
	else if (mEp->type == USB_ENDPOINT_XFER_ISOC)
		mEp->qh.ptr->cap &= ~QH_MULT;
	else
		mEp->qh.ptr->cap &= ~QH_ZLT;

	mEp->qh.ptr->cap |=
		(mEp->ep.maxpacket << ffs_nr(QH_MAX_PKT)) & QH_MAX_PKT;
	mEp->qh.ptr->td.next |= TD_TERMINATE;   /* needed? */

	/*
	 * Enable endpoints in the HW other than ep0 as ep0
	 * is always enabled
	 */
	if (mEp->num)
		retval |= hw_ep_enable(mEp->udc, mEp->num, mEp->dir, mEp->type);

	spin_unlock_irqrestore(mEp->lock, flags);
	return retval;
}

/**
 * ep_disable: endpoint is no longer usable
 *
 * Check usb_ep_disable() at "usb_gadget.h" for details
 */
static int ep_disable(struct usb_ep *ep)
{
	struct ci13xxx_ep *mEp = container_of(ep, struct ci13xxx_ep, ep);
	int direction, retval = 0;
	unsigned long flags;

	if (ep == NULL)
		return -EINVAL;
	else if (mEp->ep.desc == NULL)
		return -EBUSY;

	spin_lock_irqsave(mEp->lock, flags);

	/* only internal SW should disable ctrl endpts */

	direction = mEp->dir;
	do {
		dbg_event(_usb_addr(mEp), "DISABLE", 0);

		retval |= _ep_nuke(mEp);
		retval |= hw_ep_disable(mEp->udc, mEp->num, mEp->dir);

		if (mEp->type == USB_ENDPOINT_XFER_CONTROL)
			mEp->dir = (mEp->dir == TX) ? RX : TX;

	} while (mEp->dir != direction);

	mEp->ep.desc = NULL;

	spin_unlock_irqrestore(mEp->lock, flags);
	return retval;
}

/**
 * ep_alloc_request: allocate a request object to use with this endpoint
 *
 * Check usb_ep_alloc_request() at "usb_gadget.h" for details
 */
static struct usb_request *ep_alloc_request(struct usb_ep *ep, gfp_t gfp_flags)
{
	struct ci13xxx_ep  *mEp  = container_of(ep, struct ci13xxx_ep, ep);
	struct ci13xxx_req *mReq = NULL;

	if (ep == NULL)
		return NULL;

	mReq = kzalloc(sizeof(struct ci13xxx_req), gfp_flags);
	if (mReq != NULL) {
		INIT_LIST_HEAD(&mReq->queue);
		mReq->req.dma = DMA_ADDR_INVALID;

		mReq->ptr = dma_pool_alloc(mEp->td_pool, gfp_flags,
					   &mReq->dma);
		if (mReq->ptr == NULL) {
			kfree(mReq);
			mReq = NULL;
		}
	}

	dbg_event(_usb_addr(mEp), "ALLOC", mReq == NULL);

	return (mReq == NULL) ? NULL : &mReq->req;
}

/**
 * ep_free_request: frees a request object
 *
 * Check usb_ep_free_request() at "usb_gadget.h" for details
 */
static void ep_free_request(struct usb_ep *ep, struct usb_request *req)
{
	struct ci13xxx_ep  *mEp  = container_of(ep,  struct ci13xxx_ep, ep);
	struct ci13xxx_req *mReq = container_of(req, struct ci13xxx_req, req);
	unsigned long flags;

	if (ep == NULL || req == NULL) {
		return;
	} else if (!list_empty(&mReq->queue)) {
		dev_err(mEp->udc->dev, "freeing queued request\n");
		return;
	}

	spin_lock_irqsave(mEp->lock, flags);

	if (mReq->ptr)
		dma_pool_free(mEp->td_pool, mReq->ptr, mReq->dma);
	kfree(mReq);

	dbg_event(_usb_addr(mEp), "FREE", 0);

	spin_unlock_irqrestore(mEp->lock, flags);
}

/**
 * ep_queue: queues (submits) an I/O request to an endpoint
 *
 * Check usb_ep_queue()* at usb_gadget.h" for details
 */
static int ep_queue(struct usb_ep *ep, struct usb_request *req,
		    gfp_t __maybe_unused gfp_flags)
{
	struct ci13xxx_ep  *mEp  = container_of(ep,  struct ci13xxx_ep, ep);
	struct ci13xxx_req *mReq = container_of(req, struct ci13xxx_req, req);
	struct ci13xxx *udc = mEp->udc;
	int retval = 0;
	unsigned long flags;

	if (ep == NULL || req == NULL || mEp->ep.desc == NULL)
		return -EINVAL;

	spin_lock_irqsave(mEp->lock, flags);

	if (mEp->type == USB_ENDPOINT_XFER_CONTROL) {
		if (req->length)
			mEp = (udc->ep0_dir == RX) ?
			       udc->ep0out : udc->ep0in;
		if (!list_empty(&mEp->qh.queue)) {
			_ep_nuke(mEp);
			retval = -EOVERFLOW;
			dev_warn(mEp->udc->dev, "endpoint ctrl %X nuked\n",
				 _usb_addr(mEp));
		}
	}

	/* first nuke then test link, e.g. previous status has not sent */
	if (!list_empty(&mReq->queue)) {
		retval = -EBUSY;
		dev_err(mEp->udc->dev, "request already in queue\n");
		goto done;
	}

	if (req->length > 4 * CI13XXX_PAGE_SIZE) {
		req->length = 4 * CI13XXX_PAGE_SIZE;
		retval = -EMSGSIZE;
		dev_warn(mEp->udc->dev, "request length truncated\n");
	}

	dbg_queue(_usb_addr(mEp), req, retval);

	/* push request */
	mReq->req.status = -EINPROGRESS;
	mReq->req.actual = 0;

	retval = _hardware_enqueue(mEp, mReq);

	if (retval == -EALREADY) {
		dbg_event(_usb_addr(mEp), "QUEUE", retval);
		retval = 0;
	}
	if (!retval)
		list_add_tail(&mReq->queue, &mEp->qh.queue);

 done:
	spin_unlock_irqrestore(mEp->lock, flags);
	return retval;
}

/**
 * ep_dequeue: dequeues (cancels, unlinks) an I/O request from an endpoint
 *
 * Check usb_ep_dequeue() at "usb_gadget.h" for details
 */
static int ep_dequeue(struct usb_ep *ep, struct usb_request *req)
{
	struct ci13xxx_ep  *mEp  = container_of(ep,  struct ci13xxx_ep, ep);
	struct ci13xxx_req *mReq = container_of(req, struct ci13xxx_req, req);
	unsigned long flags;

	if (ep == NULL || req == NULL || mReq->req.status != -EALREADY ||
		mEp->ep.desc == NULL || list_empty(&mReq->queue) ||
		list_empty(&mEp->qh.queue))
		return -EINVAL;

	spin_lock_irqsave(mEp->lock, flags);

	dbg_event(_usb_addr(mEp), "DEQUEUE", 0);

	hw_ep_flush(mEp->udc, mEp->num, mEp->dir);

	/* pop request */
	list_del_init(&mReq->queue);
	if (mReq->map) {
		dma_unmap_single(mEp->device, mReq->req.dma, mReq->req.length,
				 mEp->dir ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
		mReq->req.dma = DMA_ADDR_INVALID;
		mReq->map     = 0;
	}
	req->status = -ECONNRESET;

	if (mReq->req.complete != NULL) {
		spin_unlock(mEp->lock);
		mReq->req.complete(&mEp->ep, &mReq->req);
		spin_lock(mEp->lock);
	}

	spin_unlock_irqrestore(mEp->lock, flags);
	return 0;
}

/**
 * ep_set_halt: sets the endpoint halt feature
 *
 * Check usb_ep_set_halt() at "usb_gadget.h" for details
 */
static int ep_set_halt(struct usb_ep *ep, int value)
{
	struct ci13xxx_ep *mEp = container_of(ep, struct ci13xxx_ep, ep);
	int direction, retval = 0;
	unsigned long flags;

	if (ep == NULL || mEp->ep.desc == NULL)
		return -EINVAL;

	spin_lock_irqsave(mEp->lock, flags);

#ifndef STALL_IN
	/* g_file_storage MS compliant but g_zero fails chapter 9 compliance */
	if (value && mEp->type == USB_ENDPOINT_XFER_BULK && mEp->dir == TX &&
	    !list_empty(&mEp->qh.queue)) {
		spin_unlock_irqrestore(mEp->lock, flags);
		return -EAGAIN;
	}
#endif

	direction = mEp->dir;
	do {
		dbg_event(_usb_addr(mEp), "HALT", value);
		retval |= hw_ep_set_halt(mEp->udc, mEp->num, mEp->dir, value);

		if (!value)
			mEp->wedge = 0;

		if (mEp->type == USB_ENDPOINT_XFER_CONTROL)
			mEp->dir = (mEp->dir == TX) ? RX : TX;

	} while (mEp->dir != direction);

	spin_unlock_irqrestore(mEp->lock, flags);
	return retval;
}

/**
 * ep_set_wedge: sets the halt feature and ignores clear requests
 *
 * Check usb_ep_set_wedge() at "usb_gadget.h" for details
 */
static int ep_set_wedge(struct usb_ep *ep)
{
	struct ci13xxx_ep *mEp = container_of(ep, struct ci13xxx_ep, ep);
	unsigned long flags;

	if (ep == NULL || mEp->ep.desc == NULL)
		return -EINVAL;

	spin_lock_irqsave(mEp->lock, flags);

	dbg_event(_usb_addr(mEp), "WEDGE", 0);
	mEp->wedge = 1;

	spin_unlock_irqrestore(mEp->lock, flags);

	return usb_ep_set_halt(ep);
}

/**
 * ep_fifo_flush: flushes contents of a fifo
 *
 * Check usb_ep_fifo_flush() at "usb_gadget.h" for details
 */
static void ep_fifo_flush(struct usb_ep *ep)
{
	struct ci13xxx_ep *mEp = container_of(ep, struct ci13xxx_ep, ep);
	unsigned long flags;

	if (ep == NULL) {
		dev_err(mEp->udc->dev, "%02X: -EINVAL\n", _usb_addr(mEp));
		return;
	}

	spin_lock_irqsave(mEp->lock, flags);

	dbg_event(_usb_addr(mEp), "FFLUSH", 0);
	hw_ep_flush(mEp->udc, mEp->num, mEp->dir);

	spin_unlock_irqrestore(mEp->lock, flags);
}

/**
 * Endpoint-specific part of the API to the USB controller hardware
 * Check "usb_gadget.h" for details
 */
static const struct usb_ep_ops usb_ep_ops = {
	.enable	       = ep_enable,
	.disable       = ep_disable,
	.alloc_request = ep_alloc_request,
	.free_request  = ep_free_request,
	.queue	       = ep_queue,
	.dequeue       = ep_dequeue,
	.set_halt      = ep_set_halt,
	.set_wedge     = ep_set_wedge,
	.fifo_flush    = ep_fifo_flush,
};

/******************************************************************************
 * GADGET block
 *****************************************************************************/
static int ci13xxx_vbus_session(struct usb_gadget *_gadget, int is_active)
{
	struct ci13xxx *udc = container_of(_gadget, struct ci13xxx, gadget);
	unsigned long flags;
	int gadget_ready = 0;

	if (!(udc->udc_driver->flags & CI13XXX_PULLUP_ON_VBUS))
		return -EOPNOTSUPP;

	spin_lock_irqsave(&udc->lock, flags);
	udc->vbus_active = is_active;
	if (udc->driver)
		gadget_ready = 1;
	spin_unlock_irqrestore(&udc->lock, flags);

	if (gadget_ready) {
		if (is_active) {
			pm_runtime_get_sync(&_gadget->dev);
			hw_device_reset(udc);
			hw_device_state(udc, udc->ep0out->qh.dma);
		} else {
			hw_device_state(udc, 0);
			if (udc->udc_driver->notify_event)
				udc->udc_driver->notify_event(udc,
				CI13XXX_CONTROLLER_STOPPED_EVENT);
			_gadget_stop_activity(&udc->gadget);
			pm_runtime_put_sync(&_gadget->dev);
		}
	}

	return 0;
}

static int ci13xxx_wakeup(struct usb_gadget *_gadget)
{
	struct ci13xxx *udc = container_of(_gadget, struct ci13xxx, gadget);
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&udc->lock, flags);
	if (!udc->remote_wakeup) {
		ret = -EOPNOTSUPP;
		goto out;
	}
	if (!hw_read(udc, OP_PORTSC, PORTSC_SUSP)) {
		ret = -EINVAL;
		goto out;
	}
	hw_write(udc, OP_PORTSC, PORTSC_FPR, PORTSC_FPR);
out:
	spin_unlock_irqrestore(&udc->lock, flags);
	return ret;
}

static int ci13xxx_vbus_draw(struct usb_gadget *_gadget, unsigned mA)
{
	struct ci13xxx *udc = container_of(_gadget, struct ci13xxx, gadget);

	if (udc->transceiver)
		return usb_phy_set_power(udc->transceiver, mA);
	return -ENOTSUPP;
}

static int ci13xxx_start(struct usb_gadget *gadget,
			 struct usb_gadget_driver *driver);
static int ci13xxx_stop(struct usb_gadget *gadget,
			struct usb_gadget_driver *driver);
/**
 * Device operations part of the API to the USB controller hardware,
 * which don't involve endpoints (or i/o)
 * Check  "usb_gadget.h" for details
 */
static const struct usb_gadget_ops usb_gadget_ops = {
	.vbus_session	= ci13xxx_vbus_session,
	.wakeup		= ci13xxx_wakeup,
	.vbus_draw	= ci13xxx_vbus_draw,
	.udc_start	= ci13xxx_start,
	.udc_stop	= ci13xxx_stop,
};

static int init_eps(struct ci13xxx *udc)
{
	int retval = 0, i, j;

	for (i = 0; i < udc->hw_ep_max/2; i++)
		for (j = RX; j <= TX; j++) {
			int k = i + j * udc->hw_ep_max/2;
			struct ci13xxx_ep *mEp = &udc->ci13xxx_ep[k];

			scnprintf(mEp->name, sizeof(mEp->name), "ep%i%s", i,
					(j == TX)  ? "in" : "out");

			mEp->udc          = udc;
			mEp->lock         = &udc->lock;
			mEp->device       = &udc->gadget.dev;
			mEp->td_pool      = udc->td_pool;

			mEp->ep.name      = mEp->name;
			mEp->ep.ops       = &usb_ep_ops;
			mEp->ep.maxpacket = CTRL_PAYLOAD_MAX;

			INIT_LIST_HEAD(&mEp->qh.queue);
			mEp->qh.ptr = dma_pool_alloc(udc->qh_pool, GFP_KERNEL,
						     &mEp->qh.dma);
			if (mEp->qh.ptr == NULL)
				retval = -ENOMEM;
			else
				memset(mEp->qh.ptr, 0, sizeof(*mEp->qh.ptr));

			/*
			 * set up shorthands for ep0 out and in endpoints,
			 * don't add to gadget's ep_list
			 */
			if (i == 0) {
				if (j == RX)
					udc->ep0out = mEp;
				else
					udc->ep0in = mEp;

				continue;
			}

			list_add_tail(&mEp->ep.ep_list, &udc->gadget.ep_list);
		}

	return retval;
}

/**
 * ci13xxx_start: register a gadget driver
 * @gadget: our gadget
 * @driver: the driver being registered
 *
 * Interrupts are enabled here.
 */
static int ci13xxx_start(struct usb_gadget *gadget,
			 struct usb_gadget_driver *driver)
{
	struct ci13xxx *udc = container_of(gadget, struct ci13xxx, gadget);
	unsigned long flags;
	int retval = -ENOMEM;

	if (driver->disconnect == NULL)
		return -EINVAL;


	udc->ep0out->ep.desc = &ctrl_endpt_out_desc;
	retval = usb_ep_enable(&udc->ep0out->ep);
	if (retval)
		return retval;

	udc->ep0in->ep.desc = &ctrl_endpt_in_desc;
	retval = usb_ep_enable(&udc->ep0in->ep);
	if (retval)
		return retval;
	spin_lock_irqsave(&udc->lock, flags);

	udc->driver = driver;
	pm_runtime_get_sync(&udc->gadget.dev);
	if (udc->udc_driver->flags & CI13XXX_PULLUP_ON_VBUS) {
		if (udc->vbus_active) {
			if (udc->udc_driver->flags & CI13XXX_REGS_SHARED)
				hw_device_reset(udc);
		} else {
			pm_runtime_put_sync(&udc->gadget.dev);
			goto done;
		}
	}

	retval = hw_device_state(udc, udc->ep0out->qh.dma);
	if (retval)
		pm_runtime_put_sync(&udc->gadget.dev);

 done:
	spin_unlock_irqrestore(&udc->lock, flags);
	return retval;
}

/**
 * ci13xxx_stop: unregister a gadget driver
 */
static int ci13xxx_stop(struct usb_gadget *gadget,
			struct usb_gadget_driver *driver)
{
	struct ci13xxx *udc = container_of(gadget, struct ci13xxx, gadget);
	unsigned long flags;

	spin_lock_irqsave(&udc->lock, flags);

	if (!(udc->udc_driver->flags & CI13XXX_PULLUP_ON_VBUS) ||
			udc->vbus_active) {
		hw_device_state(udc, 0);
		if (udc->udc_driver->notify_event)
			udc->udc_driver->notify_event(udc,
			CI13XXX_CONTROLLER_STOPPED_EVENT);
		udc->driver = NULL;
		spin_unlock_irqrestore(&udc->lock, flags);
		_gadget_stop_activity(&udc->gadget);
		spin_lock_irqsave(&udc->lock, flags);
		pm_runtime_put(&udc->gadget.dev);
	}

	spin_unlock_irqrestore(&udc->lock, flags);

	return 0;
}

/******************************************************************************
 * BUS block
 *****************************************************************************/
/**
 * udc_irq: udc interrupt handler
 *
 * This function returns IRQ_HANDLED if the IRQ has been handled
 * It locks access to registers
 */
static irqreturn_t udc_irq(struct ci13xxx *udc)
{
	irqreturn_t retval;
	u32 intr;

	if (udc == NULL)
		return IRQ_HANDLED;

	spin_lock(&udc->lock);

	if (udc->udc_driver->flags & CI13XXX_REGS_SHARED) {
		if (hw_read(udc, OP_USBMODE, USBMODE_CM) !=
				USBMODE_CM_DEVICE) {
			spin_unlock(&udc->lock);
			return IRQ_NONE;
		}
	}
	intr = hw_test_and_clear_intr_active(udc);
	dbg_interrupt(intr);

	if (intr) {
		/* order defines priority - do NOT change it */
		if (USBi_URI & intr)
			isr_reset_handler(udc);

		if (USBi_PCI & intr) {
			udc->gadget.speed = hw_port_is_high_speed(udc) ?
				USB_SPEED_HIGH : USB_SPEED_FULL;
			if (udc->suspended && udc->driver->resume) {
				spin_unlock(&udc->lock);
				udc->driver->resume(&udc->gadget);
				spin_lock(&udc->lock);
				udc->suspended = 0;
			}
		}

		if (USBi_UI  & intr)
			isr_tr_complete_handler(udc);

		if (USBi_SLI & intr) {
			if (udc->gadget.speed != USB_SPEED_UNKNOWN &&
			    udc->driver->suspend) {
				udc->suspended = 1;
				spin_unlock(&udc->lock);
				udc->driver->suspend(&udc->gadget);
				spin_lock(&udc->lock);
			}
		}
		retval = IRQ_HANDLED;
	} else {
		retval = IRQ_NONE;
	}
	spin_unlock(&udc->lock);

	return retval;
}

/**
 * udc_release: driver release function
 * @dev: device
 *
 * Currently does nothing
 */
static void udc_release(struct device *dev)
{
}

/**
 * udc_start: initialize gadget role
 * @udc: chipidea controller
 */
static int udc_start(struct ci13xxx *udc)
{
	struct device *dev = udc->dev;
	int retval = 0;

	if (!udc)
		return -EINVAL;

	spin_lock_init(&udc->lock);

	udc->gadget.ops          = &usb_gadget_ops;
	udc->gadget.speed        = USB_SPEED_UNKNOWN;
	udc->gadget.max_speed    = USB_SPEED_HIGH;
	udc->gadget.is_otg       = 0;
	udc->gadget.name         = udc->udc_driver->name;

	INIT_LIST_HEAD(&udc->gadget.ep_list);

	dev_set_name(&udc->gadget.dev, "gadget");
	udc->gadget.dev.dma_mask = dev->dma_mask;
	udc->gadget.dev.coherent_dma_mask = dev->coherent_dma_mask;
	udc->gadget.dev.parent   = dev;
	udc->gadget.dev.release  = udc_release;

	/* alloc resources */
	udc->qh_pool = dma_pool_create("ci13xxx_qh", dev,
				       sizeof(struct ci13xxx_qh),
				       64, CI13XXX_PAGE_SIZE);
	if (udc->qh_pool == NULL)
		return -ENOMEM;

	udc->td_pool = dma_pool_create("ci13xxx_td", dev,
				       sizeof(struct ci13xxx_td),
				       64, CI13XXX_PAGE_SIZE);
	if (udc->td_pool == NULL) {
		retval = -ENOMEM;
		goto free_qh_pool;
	}

	retval = init_eps(udc);
	if (retval)
		goto free_pools;

	udc->gadget.ep0 = &udc->ep0in->ep;

	udc->transceiver = usb_get_transceiver();

	if (udc->udc_driver->flags & CI13XXX_REQUIRE_TRANSCEIVER) {
		if (udc->transceiver == NULL) {
			retval = -ENODEV;
			goto free_pools;
		}
	}

	if (!(udc->udc_driver->flags & CI13XXX_REGS_SHARED)) {
		retval = hw_device_reset(udc);
		if (retval)
			goto put_transceiver;
	}

	retval = device_register(&udc->gadget.dev);
	if (retval) {
		put_device(&udc->gadget.dev);
		goto put_transceiver;
	}

	retval = dbg_create_files(&udc->gadget.dev);
	if (retval)
		goto unreg_device;

	if (udc->transceiver) {
		retval = otg_set_peripheral(udc->transceiver->otg,
						&udc->gadget);
		if (retval)
			goto remove_dbg;
	}

	retval = usb_add_gadget_udc(dev, &udc->gadget);
	if (retval)
		goto remove_trans;

	pm_runtime_no_callbacks(&udc->gadget.dev);
	pm_runtime_enable(&udc->gadget.dev);

	return retval;

remove_trans:
	if (udc->transceiver) {
		otg_set_peripheral(udc->transceiver->otg, &udc->gadget);
		usb_put_transceiver(udc->transceiver);
	}

	dev_err(dev, "error = %i\n", retval);
remove_dbg:
	dbg_remove_files(&udc->gadget.dev);
unreg_device:
	device_unregister(&udc->gadget.dev);
put_transceiver:
	if (udc->transceiver)
		usb_put_transceiver(udc->transceiver);
free_pools:
	dma_pool_destroy(udc->td_pool);
free_qh_pool:
	dma_pool_destroy(udc->qh_pool);
	return retval;
}

/**
 * udc_remove: parent remove must call this to remove UDC
 *
 * No interrupts active, the IRQ has been released
 */
static void udc_stop(struct ci13xxx *udc)
{
	int i;

	if (udc == NULL)
		return;

	usb_del_gadget_udc(&udc->gadget);

	for (i = 0; i < udc->hw_ep_max; i++) {
		struct ci13xxx_ep *mEp = &udc->ci13xxx_ep[i];

		dma_pool_free(udc->qh_pool, mEp->qh.ptr, mEp->qh.dma);
	}

	dma_pool_destroy(udc->td_pool);
	dma_pool_destroy(udc->qh_pool);

	if (udc->transceiver) {
		otg_set_peripheral(udc->transceiver->otg, NULL);
		usb_put_transceiver(udc->transceiver);
	}
	dbg_remove_files(&udc->gadget.dev);
	device_unregister(&udc->gadget.dev);
	/* my kobject is dynamic, I swear! */
	memset(&udc->gadget, 0, sizeof(udc->gadget));
}

/**
 * ci_hdrc_gadget_init - initialize device related bits
 * ci: the controller
 *
 * This function enables the gadget role, if the device is "device capable".
 */
int ci_hdrc_gadget_init(struct ci13xxx *ci)
{
	struct ci_role_driver *rdrv;

	if (!hw_read(ci, CAP_DCCPARAMS, DCCPARAMS_DC))
		return -ENXIO;

	rdrv = devm_kzalloc(ci->dev, sizeof(struct ci_role_driver), GFP_KERNEL);
	if (!rdrv)
		return -ENOMEM;

	rdrv->start	= udc_start;
	rdrv->stop	= udc_stop;
	rdrv->irq	= udc_irq;
	rdrv->name	= "gadget";
	ci->roles[CI_ROLE_GADGET] = rdrv;

	return 0;
}