// SPDX-License-Identifier: GPL-2.0
/*
 * udc.c - ChipIdea UDC driver
 *
 * Copyright (C) 2008 Chipidea - MIPS Technologies, Inc. All rights reserved.
 *
 * Author: David Lopo
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/irqreturn.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/pinctrl/consumer.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/otg-fsm.h>
#include <linux/usb/chipidea.h>

#include "ci.h"
#include "udc.h"
#include "bits.h"
#include "otg.h"
#include "otg_fsm.h"
#include "trace.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 == TX) ? 16 : 0);
}

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

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

        return n;
}

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

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

        do {
                /* flush any pending transfer */
                hw_write(ci, OP_ENDPTFLUSH, ~0, BIT(n));
                while (hw_read(ci, OP_ENDPTFLUSH, BIT(n)))
                        cpu_relax();
        } while (hw_read(ci, OP_ENDPTSTAT, BIT(n)));

        return 0;
}

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

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

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

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

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

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

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

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

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

        hw_write(ci, OP_ENDPTPRIME, ~0, BIT(n));

        while (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
                cpu_relax();
        if (is_ctrl && dir == RX && hw_read(ci, 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)
 * @ci: the controller
 * @num:   endpoint number
 * @dir:   endpoint direction
 * @value: true => stall, false => unstall
 *
 * This function returns an error code
 */
static int hw_ep_set_halt(struct ci_hdrc *ci, int num, int dir, int value)
{
        if (value != 0 && value != 1)
                return -EINVAL;

        do {
                enum ci_hw_regs reg = OP_ENDPTCTRL + num;
                u32 mask_xs = (dir == TX) ? ENDPTCTRL_TXS : ENDPTCTRL_RXS;
                u32 mask_xr = (dir == TX) ? ENDPTCTRL_TXR : ENDPTCTRL_RXR;

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

        return 0;
}

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

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

/**
 * hw_test_and_clear_intr_active: test & clear active interrupts (execute
 *                                without interruption)
 * @ci: the controller
 *
 * This function returns active interrutps
 */
static u32 hw_test_and_clear_intr_active(struct ci_hdrc *ci)
{
        u32 reg = hw_read_intr_status(ci) & hw_read_intr_enable(ci);

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

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

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

/**
 * hw_usb_set_address: configures USB address (execute without interruption)
 * @ci: the controller
 * @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 ci_hdrc *ci, u8 value)
{
        hw_write(ci, OP_DEVICEADDR, DEVICEADDR_USBADR,
                 value << __ffs(DEVICEADDR_USBADR));
}

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

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

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

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

        /* wait until all bits cleared */
        while (hw_read(ci, 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
 *****************************************************************************/

static int add_td_to_list(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq,
                        unsigned int length, struct scatterlist *s)
{
        int i;
        u32 temp;
        struct td_node *lastnode, *node = kzalloc(sizeof(struct td_node),
                                                  GFP_ATOMIC);

        if (node == NULL)
                return -ENOMEM;

        node->ptr = dma_pool_zalloc(hwep->td_pool, GFP_ATOMIC, &node->dma);
        if (node->ptr == NULL) {
                kfree(node);
                return -ENOMEM;
        }

        node->ptr->token = cpu_to_le32(length << __ffs(TD_TOTAL_BYTES));
        node->ptr->token &= cpu_to_le32(TD_TOTAL_BYTES);
        node->ptr->token |= cpu_to_le32(TD_STATUS_ACTIVE);
        if (hwep->type == USB_ENDPOINT_XFER_ISOC && hwep->dir == TX) {
                u32 mul = hwreq->req.length / hwep->ep.maxpacket;

                if (hwreq->req.length == 0
                                || hwreq->req.length % hwep->ep.maxpacket)
                        mul++;
                node->ptr->token |= cpu_to_le32(mul << __ffs(TD_MULTO));
        }

        if (s) {
                temp = (u32) (sg_dma_address(s) + hwreq->req.actual);
                node->td_remaining_size = CI_MAX_BUF_SIZE - length;
        } else {
                temp = (u32) (hwreq->req.dma + hwreq->req.actual);
        }

        if (length) {
                node->ptr->page[0] = cpu_to_le32(temp);
                for (i = 1; i < TD_PAGE_COUNT; i++) {
                        u32 page = temp + i * CI_HDRC_PAGE_SIZE;
                        page &= ~TD_RESERVED_MASK;
                        node->ptr->page[i] = cpu_to_le32(page);
                }
        }

        hwreq->req.actual += length;

        if (!list_empty(&hwreq->tds)) {
                /* get the last entry */
                lastnode = list_entry(hwreq->tds.prev,
                                struct td_node, td);
                lastnode->ptr->next = cpu_to_le32(node->dma);
        }

        INIT_LIST_HEAD(&node->td);
        list_add_tail(&node->td, &hwreq->tds);

        return 0;
}

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

static int prepare_td_for_non_sg(struct ci_hw_ep *hwep,
                struct ci_hw_req *hwreq)
{
        unsigned int rest = hwreq->req.length;
        int pages = TD_PAGE_COUNT;
        int ret = 0;

        if (rest == 0) {
                ret = add_td_to_list(hwep, hwreq, 0, NULL);
                if (ret < 0)
                        return ret;
        }

        /*
         * The first buffer could be not page aligned.
         * In that case we have to span into one extra td.
         */
        if (hwreq->req.dma % PAGE_SIZE)
                pages--;

        while (rest > 0) {
                unsigned int count = min(hwreq->req.length - hwreq->req.actual,
                        (unsigned int)(pages * CI_HDRC_PAGE_SIZE));

                ret = add_td_to_list(hwep, hwreq, count, NULL);
                if (ret < 0)
                        return ret;

                rest -= count;
        }

        if (hwreq->req.zero && hwreq->req.length && hwep->dir == TX
            && (hwreq->req.length % hwep->ep.maxpacket == 0)) {
                ret = add_td_to_list(hwep, hwreq, 0, NULL);
                if (ret < 0)
                        return ret;
        }

        return ret;
}

static int prepare_td_per_sg(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq,
                struct scatterlist *s)
{
        unsigned int rest = sg_dma_len(s);
        int ret = 0;

        hwreq->req.actual = 0;
        while (rest > 0) {
                unsigned int count = min_t(unsigned int, rest,
                                CI_MAX_BUF_SIZE);

                ret = add_td_to_list(hwep, hwreq, count, s);
                if (ret < 0)
                        return ret;

                rest -= count;
        }

        return ret;
}

static void ci_add_buffer_entry(struct td_node *node, struct scatterlist *s)
{
        int empty_td_slot_index = (CI_MAX_BUF_SIZE - node->td_remaining_size)
                        / CI_HDRC_PAGE_SIZE;
        int i;
        u32 token;

        token = le32_to_cpu(node->ptr->token) + (sg_dma_len(s) << __ffs(TD_TOTAL_BYTES));
        node->ptr->token = cpu_to_le32(token);

        for (i = empty_td_slot_index; i < TD_PAGE_COUNT; i++) {
                u32 page = (u32) sg_dma_address(s) +
                        (i - empty_td_slot_index) * CI_HDRC_PAGE_SIZE;

                page &= ~TD_RESERVED_MASK;
                node->ptr->page[i] = cpu_to_le32(page);
        }
}

static int prepare_td_for_sg(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
{
        struct usb_request *req = &hwreq->req;
        struct scatterlist *s = req->sg;
        int ret = 0, i = 0;
        struct td_node *node = NULL;

        if (!s || req->zero || req->length == 0) {
                dev_err(hwep->ci->dev, "not supported operation for sg\n");
                return -EINVAL;
        }

        while (i++ < req->num_mapped_sgs) {
                if (sg_dma_address(s) % PAGE_SIZE) {
                        dev_err(hwep->ci->dev, "not page aligned sg buffer\n");
                        return -EINVAL;
                }

                if (node && (node->td_remaining_size >= sg_dma_len(s))) {
                        ci_add_buffer_entry(node, s);
                        node->td_remaining_size -= sg_dma_len(s);
                } else {
                        ret = prepare_td_per_sg(hwep, hwreq, s);
                        if (ret)
                                return ret;

                        node = list_entry(hwreq->tds.prev,
                                struct td_node, td);
                }

                s = sg_next(s);
        }

        return ret;
}

/**
 * _hardware_enqueue: configures a request at hardware level
 * @hwep:   endpoint
 * @hwreq:  request
 *
 * This function returns an error code
 */
static int _hardware_enqueue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
{
        struct ci_hdrc *ci = hwep->ci;
        int ret = 0;
        struct td_node *firstnode, *lastnode;

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

        hwreq->req.status = -EALREADY;

        ret = usb_gadget_map_request_by_dev(ci->dev->parent,
                                            &hwreq->req, hwep->dir);
        if (ret)
                return ret;

        if (hwreq->req.num_mapped_sgs)
                ret = prepare_td_for_sg(hwep, hwreq);
        else
                ret = prepare_td_for_non_sg(hwep, hwreq);

        if (ret)
                return ret;

        lastnode = list_entry(hwreq->tds.prev,
                struct td_node, td);

        lastnode->ptr->next = cpu_to_le32(TD_TERMINATE);
        if (!hwreq->req.no_interrupt)
                lastnode->ptr->token |= cpu_to_le32(TD_IOC);

        list_for_each_entry_safe(firstnode, lastnode, &hwreq->tds, td)
                trace_ci_prepare_td(hwep, hwreq, firstnode);

        firstnode = list_first_entry(&hwreq->tds, struct td_node, td);

        wmb();

        hwreq->req.actual = 0;
        if (!list_empty(&hwep->qh.queue)) {
                struct ci_hw_req *hwreqprev;
                int n = hw_ep_bit(hwep->num, hwep->dir);
                int tmp_stat;
                struct td_node *prevlastnode;
                u32 next = firstnode->dma & TD_ADDR_MASK;

                hwreqprev = list_entry(hwep->qh.queue.prev,
                                struct ci_hw_req, queue);
                prevlastnode = list_entry(hwreqprev->tds.prev,
                                struct td_node, td);

                prevlastnode->ptr->next = cpu_to_le32(next);
                wmb();
                if (hw_read(ci, OP_ENDPTPRIME, BIT(n)))
                        goto done;
                do {
                        hw_write(ci, OP_USBCMD, USBCMD_ATDTW, USBCMD_ATDTW);
                        tmp_stat = hw_read(ci, OP_ENDPTSTAT, BIT(n));
                } while (!hw_read(ci, OP_USBCMD, USBCMD_ATDTW));
                hw_write(ci, OP_USBCMD, USBCMD_ATDTW, 0);
                if (tmp_stat)
                        goto done;
        }

        /*  QH configuration */
        hwep->qh.ptr->td.next = cpu_to_le32(firstnode->dma);
        hwep->qh.ptr->td.token &=
                cpu_to_le32(~(TD_STATUS_HALTED|TD_STATUS_ACTIVE));

        if (hwep->type == USB_ENDPOINT_XFER_ISOC && hwep->dir == RX) {
                u32 mul = hwreq->req.length / hwep->ep.maxpacket;

                if (hwreq->req.length == 0
                                || hwreq->req.length % hwep->ep.maxpacket)
                        mul++;
                hwep->qh.ptr->cap |= cpu_to_le32(mul << __ffs(QH_MULT));
        }

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

/**
 * free_pending_td: remove a pending request for the endpoint
 * @hwep: endpoint
 */
static void free_pending_td(struct ci_hw_ep *hwep)
{
        struct td_node *pending = hwep->pending_td;

        dma_pool_free(hwep->td_pool, pending->ptr, pending->dma);
        hwep->pending_td = NULL;
        kfree(pending);
}

static int reprime_dtd(struct ci_hdrc *ci, struct ci_hw_ep *hwep,
                                           struct td_node *node)
{
        hwep->qh.ptr->td.next = cpu_to_le32(node->dma);
        hwep->qh.ptr->td.token &=
                cpu_to_le32(~(TD_STATUS_HALTED | TD_STATUS_ACTIVE));

        return hw_ep_prime(ci, hwep->num, hwep->dir,
                                hwep->type == USB_ENDPOINT_XFER_CONTROL);
}

/**
 * _hardware_dequeue: handles a request at hardware level
 * @hwep: endpoint
 * @hwreq:  request
 *
 * This function returns an error code
 */
static int _hardware_dequeue(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq)
{
        u32 tmptoken;
        struct td_node *node, *tmpnode;
        unsigned remaining_length;
        unsigned actual = hwreq->req.length;
        struct ci_hdrc *ci = hwep->ci;

        if (hwreq->req.status != -EALREADY)
                return -EINVAL;

        hwreq->req.status = 0;

        list_for_each_entry_safe(node, tmpnode, &hwreq->tds, td) {
                tmptoken = le32_to_cpu(node->ptr->token);
                trace_ci_complete_td(hwep, hwreq, node);
                if ((TD_STATUS_ACTIVE & tmptoken) != 0) {
                        int n = hw_ep_bit(hwep->num, hwep->dir);

                        if (ci->rev == CI_REVISION_24)
                                if (!hw_read(ci, OP_ENDPTSTAT, BIT(n)))
                                        reprime_dtd(ci, hwep, node);
                        hwreq->req.status = -EALREADY;
                        return -EBUSY;
                }

                remaining_length = (tmptoken & TD_TOTAL_BYTES);
                remaining_length >>= __ffs(TD_TOTAL_BYTES);
                actual -= remaining_length;

                hwreq->req.status = tmptoken & TD_STATUS;
                if ((TD_STATUS_HALTED & hwreq->req.status)) {
                        hwreq->req.status = -EPIPE;
                        break;
                } else if ((TD_STATUS_DT_ERR & hwreq->req.status)) {
                        hwreq->req.status = -EPROTO;
                        break;
                } else if ((TD_STATUS_TR_ERR & hwreq->req.status)) {
                        hwreq->req.status = -EILSEQ;
                        break;
                }

                if (remaining_length) {
                        if (hwep->dir == TX) {
                                hwreq->req.status = -EPROTO;
                                break;
                        }
                }
                /*
                 * As the hardware could still address the freed td
                 * which will run the udc unusable, the cleanup of the
                 * td has to be delayed by one.
                 */
                if (hwep->pending_td)
                        free_pending_td(hwep);

                hwep->pending_td = node;
                list_del_init(&node->td);
        }

        usb_gadget_unmap_request_by_dev(hwep->ci->dev->parent,
                                        &hwreq->req, hwep->dir);

        hwreq->req.actual += actual;

        if (hwreq->req.status)
                return hwreq->req.status;

        return hwreq->req.actual;
}

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

        hw_ep_flush(hwep->ci, hwep->num, hwep->dir);

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

                /* pop oldest request */
                struct ci_hw_req *hwreq = list_entry(hwep->qh.queue.next,
                                                     struct ci_hw_req, queue);

                list_for_each_entry_safe(node, tmpnode, &hwreq->tds, td) {
                        dma_pool_free(hwep->td_pool, node->ptr, node->dma);
                        list_del_init(&node->td);
                        node->ptr = NULL;
                        kfree(node);
                }

                list_del_init(&hwreq->queue);
                hwreq->req.status = -ESHUTDOWN;

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

        if (hwep->pending_td)
                free_pending_td(hwep);

        return 0;
}

static int _ep_set_halt(struct usb_ep *ep, int value, bool check_transfer)
{
        struct ci_hw_ep *hwep = container_of(ep, struct ci_hw_ep, ep);
        int direction, retval = 0;
        unsigned long flags;

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

        if (usb_endpoint_xfer_isoc(hwep->ep.desc))
                return -EOPNOTSUPP;

        spin_lock_irqsave(hwep->lock, flags);

        if (value && hwep->dir == TX && check_transfer &&
                !list_empty(&hwep->qh.queue) &&
                        !usb_endpoint_xfer_control(hwep->ep.desc)) {
                spin_unlock_irqrestore(hwep->lock, flags);
                return -EAGAIN;
        }

        direction = hwep->dir;
        do {
                retval |= hw_ep_set_halt(hwep->ci, hwep->num, hwep->dir, value);

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

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

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

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


/**
 * _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 ci_hdrc    *ci = container_of(gadget, struct ci_hdrc, gadget);
        unsigned long flags;

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

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

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

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

        return 0;
}

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

        spin_unlock(&ci->lock);
        if (ci->gadget.speed != USB_SPEED_UNKNOWN)
                usb_gadget_udc_reset(&ci->gadget, ci->driver);

        retval = _gadget_stop_activity(&ci->gadget);
        if (retval)
                goto done;

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

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

done:
        spin_lock(&ci->lock);

        if (retval)
                dev_err(ci->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);
}

/**
 * _ep_queue: queues (submits) an I/O request to an endpoint
 * @ep:        endpoint
 * @req:       request
 * @gfp_flags: GFP flags (not used)
 *
 * Caller must hold lock
 * This function returns an error code
 */
static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
                    gfp_t __maybe_unused gfp_flags)
{
        struct ci_hw_ep  *hwep  = container_of(ep,  struct ci_hw_ep, ep);
        struct ci_hw_req *hwreq = container_of(req, struct ci_hw_req, req);
        struct ci_hdrc *ci = hwep->ci;
        int retval = 0;

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

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

        if (usb_endpoint_xfer_isoc(hwep->ep.desc) &&
            hwreq->req.length > hwep->ep.mult * hwep->ep.maxpacket) {
                dev_err(hwep->ci->dev, "request length too big for isochronous\n");
                return -EMSGSIZE;
        }

        /* first nuke then test link, e.g. previous status has not sent */
        if (!list_empty(&hwreq->queue)) {
                dev_err(hwep->ci->dev, "request already in queue\n");
                return -EBUSY;
        }

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

        retval = _hardware_enqueue(hwep, hwreq);

        if (retval == -EALREADY)
                retval = 0;
        if (!retval)
                list_add_tail(&hwreq->queue, &hwep->qh.queue);

        return retval;
}

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

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

        spin_unlock(hwep->lock);
        req = usb_ep_alloc_request(&hwep->ep, gfp_flags);
        spin_lock(hwep->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) {
                *(u16 *)req->buf = (ci->remote_wakeup << 1) |
                        ci->gadget.is_selfpowered;
        } 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(ci, num, dir);
        }
        /* else do nothing; reserved for future use */

        retval = _ep_queue(&hwep->ep, req, gfp_flags);
        if (retval)
                goto err_free_buf;

        return 0;

 err_free_buf:
        kfree(req->buf);
 err_free_req:
        spin_unlock(hwep->lock);
        usb_ep_free_request(&hwep->ep, req);
        spin_lock(hwep->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 ci_hdrc *ci = req->context;
        unsigned long flags;

        if (ci->setaddr) {
                hw_usb_set_address(ci, ci->address);
                ci->setaddr = false;
                if (ci->address)
                        usb_gadget_set_state(&ci->gadget, USB_STATE_ADDRESS);
        }

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

/**
 * isr_setup_status_phase: queues the status phase of a setup transation
 * @ci: ci struct
 *
 * This function returns an error code
 */
static int isr_setup_status_phase(struct ci_hdrc *ci)
{
        struct ci_hw_ep *hwep;

        /*
         * Unexpected USB controller behavior, caused by bad signal integrity
         * or ground reference problems, can lead to isr_setup_status_phase
         * being called with ci->status equal to NULL.
         * If this situation occurs, you should review your USB hardware design.
         */
        if (WARN_ON_ONCE(!ci->status))
                return -EPIPE;

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

        return _ep_queue(&hwep->ep, ci->status, GFP_ATOMIC);
}

/**
 * isr_tr_complete_low: transaction complete low level handler
 * @hwep: endpoint
 *
 * This function returns an error code
 * Caller must hold lock
 */
static int isr_tr_complete_low(struct ci_hw_ep *hwep)
__releases(hwep->lock)
__acquires(hwep->lock)
{
        struct ci_hw_req *hwreq, *hwreqtemp;
        struct ci_hw_ep *hweptemp = hwep;
        int retval = 0;

        list_for_each_entry_safe(hwreq, hwreqtemp, &hwep->qh.queue,
                        queue) {
                retval = _hardware_dequeue(hwep, hwreq);
                if (retval < 0)
                        break;
                list_del_init(&hwreq->queue);
                if (hwreq->req.complete != NULL) {
                        spin_unlock(hwep->lock);
                        if ((hwep->type == USB_ENDPOINT_XFER_CONTROL) &&
                                        hwreq->req.length)
                                hweptemp = hwep->ci->ep0in;
                        usb_gadget_giveback_request(&hweptemp->ep, &hwreq->req);
                        spin_lock(hwep->lock);
                }
        }

        if (retval == -EBUSY)
                retval = 0;

        return retval;
}

static int otg_a_alt_hnp_support(struct ci_hdrc *ci)
{
        dev_warn(&ci->gadget.dev,
                "connect the device to an alternate port if you want HNP\n");
        return isr_setup_status_phase(ci);
}

/**
 * isr_setup_packet_handler: setup packet handler
 * @ci: UDC descriptor
 *
 * This function handles setup packet 
 */
static void isr_setup_packet_handler(struct ci_hdrc *ci)
__releases(ci->lock)
__acquires(ci->lock)
{
        struct ci_hw_ep *hwep = &ci->ci_hw_ep[0];
        struct usb_ctrlrequest req;
        int type, num, dir, err = -EINVAL;
        u8 tmode = 0;

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

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

        type = req.bRequestType;

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

        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) ? TX : RX;
                        num &= USB_ENDPOINT_NUMBER_MASK;
                        if (dir == TX)
                                num += ci->hw_ep_max / 2;
                        if (!ci->ci_hw_ep[num].wedge) {
                                spin_unlock(&ci->lock);
                                err = usb_ep_clear_halt(
                                        &ci->ci_hw_ep[num].ep);
                                spin_lock(&ci->lock);
                                if (err)
                                        break;
                        }
                        err = isr_setup_status_phase(ci);
                } else if (type == (USB_DIR_OUT|USB_RECIP_DEVICE) &&
                                le16_to_cpu(req.wValue) ==
                                USB_DEVICE_REMOTE_WAKEUP) {
                        if (req.wLength != 0)
                                break;
                        ci->remote_wakeup = 0;
                        err = isr_setup_status_phase(ci);
                } else {
                        goto delegate;
                }
                break;
        case USB_REQ_GET_STATUS:
                if ((type != (USB_DIR_IN|USB_RECIP_DEVICE) ||
                        le16_to_cpu(req.wIndex) == OTG_STS_SELECTOR) &&
                    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(ci, &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;
                ci->address = (u8)le16_to_cpu(req.wValue);
                ci->setaddr = true;
                err = isr_setup_status_phase(ci);
                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) ? TX : RX;
                        num &= USB_ENDPOINT_NUMBER_MASK;
                        if (dir == TX)
                                num += ci->hw_ep_max / 2;

                        spin_unlock(&ci->lock);
                        err = _ep_set_halt(&ci->ci_hw_ep[num].ep, 1, false);
                        spin_lock(&ci->lock);
                        if (!err)
                                isr_setup_status_phase(ci);
                } 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:
                                ci->remote_wakeup = 1;
                                err = isr_setup_status_phase(ci);
                                break;
                        case USB_DEVICE_TEST_MODE:
                                tmode = le16_to_cpu(req.wIndex) >> 8;
                                switch (tmode) {
                                case USB_TEST_J:
                                case USB_TEST_K:
                                case USB_TEST_SE0_NAK:
                                case USB_TEST_PACKET:
                                case USB_TEST_FORCE_ENABLE:
                                        ci->test_mode = tmode;
                                        err = isr_setup_status_phase(
                                                        ci);
                                        break;
                                default:
                                        break;
                                }
                                break;
                        case USB_DEVICE_B_HNP_ENABLE:
                                if (ci_otg_is_fsm_mode(ci)) {
                                        ci->gadget.b_hnp_enable = 1;
                                        err = isr_setup_status_phase(
                                                        ci);
                                }
                                break;
                        case USB_DEVICE_A_ALT_HNP_SUPPORT:
                                if (ci_otg_is_fsm_mode(ci))
                                        err = otg_a_alt_hnp_support(ci);
                                break;
                        case USB_DEVICE_A_HNP_SUPPORT:
                                if (ci_otg_is_fsm_mode(ci)) {
                                        ci->gadget.a_hnp_support = 1;
                                        err = isr_setup_status_phase(
                                                        ci);
                                }
                                break;
                        default:
                                goto delegate;
                        }
                } else {
                        goto delegate;
                }
                break;
        default:
delegate:
                if (req.wLength == 0)   /* no data phase */
                        ci->ep0_dir = TX;

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

        if (err < 0) {
                spin_unlock(&ci->lock);
                if (_ep_set_halt(&hwep->ep, 1, false))
                        dev_err(ci->dev, "error: _ep_set_halt\n");
                spin_lock(&ci->lock);
        }
}

/**
 * isr_tr_complete_handler: transaction complete interrupt handler
 * @ci: UDC descriptor
 *
 * This function handles traffic events
 */
static void isr_tr_complete_handler(struct ci_hdrc *ci)
__releases(ci->lock)
__acquires(ci->lock)
{
        unsigned i;
        int err;

        for (i = 0; i < ci->hw_ep_max; i++) {
                struct ci_hw_ep *hwep  = &ci->ci_hw_ep[i];

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

                if (hw_test_and_clear_complete(ci, i)) {
                        err = isr_tr_complete_low(hwep);
                        if (hwep->type == USB_ENDPOINT_XFER_CONTROL) {
                                if (err > 0)   /* needs status phase */
                                        err = isr_setup_status_phase(ci);
                                if (err < 0) {
                                        spin_unlock(&ci->lock);
                                        if (_ep_set_halt(&hwep->ep, 1, false))
                                                dev_err(ci->dev,
                                                "error: _ep_set_halt\n");
                                        spin_lock(&ci->lock);
                                }
                        }
                }

                /* Only handle setup packet below */
                if (i == 0 &&
                        hw_test_and_clear(ci, OP_ENDPTSETUPSTAT, BIT(0)))
                        isr_setup_packet_handler(ci);
        }
}

/******************************************************************************
 * 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 ci_hw_ep *hwep = container_of(ep, struct ci_hw_ep, ep);
        int retval = 0;
        unsigned long flags;
        u32 cap = 0;

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

        spin_lock_irqsave(hwep->lock, flags);

        /* only internal SW should enable ctrl endpts */

        if (!list_empty(&hwep->qh.queue)) {
                dev_warn(hwep->ci->dev, "enabling a non-empty endpoint!\n");
                spin_unlock_irqrestore(hwep->lock, flags);
                return -EBUSY;
        }

        hwep->ep.desc = desc;

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

        hwep->ep.maxpacket = usb_endpoint_maxp(desc);
        hwep->ep.mult = usb_endpoint_maxp_mult(desc);

        if (hwep->type == USB_ENDPOINT_XFER_CONTROL)
                cap |= QH_IOS;

        cap |= QH_ZLT;
        cap |= (hwep->ep.maxpacket << __ffs(QH_MAX_PKT)) & QH_MAX_PKT;
        /*
         * For ISO-TX, we set mult at QH as the largest value, and use
         * MultO at TD as real mult value.
         */
        if (hwep->type == USB_ENDPOINT_XFER_ISOC && hwep->dir == TX)
                cap |= 3 << __ffs(QH_MULT);

        hwep->qh.ptr->cap = cpu_to_le32(cap);

        hwep->qh.ptr->td.next |= cpu_to_le32(TD_TERMINATE);   /* needed? */

        if (hwep->num != 0 && hwep->type == USB_ENDPOINT_XFER_CONTROL) {
                dev_err(hwep->ci->dev, "Set control xfer at non-ep0\n");
                retval = -EINVAL;
        }

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

        spin_unlock_irqrestore(hwep->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 ci_hw_ep *hwep = container_of(ep, struct ci_hw_ep, ep);
        int direction, retval = 0;
        unsigned long flags;

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

        spin_lock_irqsave(hwep->lock, flags);
        if (hwep->ci->gadget.speed == USB_SPEED_UNKNOWN) {
                spin_unlock_irqrestore(hwep->lock, flags);
                return 0;
        }

        /* only internal SW should disable ctrl endpts */

        direction = hwep->dir;
        do {
                retval |= _ep_nuke(hwep);
                retval |= hw_ep_disable(hwep->ci, hwep->num, hwep->dir);

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

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

        hwep->ep.desc = NULL;

        spin_unlock_irqrestore(hwep->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 ci_hw_req *hwreq = NULL;

        if (ep == NULL)
                return NULL;

        hwreq = kzalloc(sizeof(struct ci_hw_req), gfp_flags);
        if (hwreq != NULL) {
                INIT_LIST_HEAD(&hwreq->queue);
                INIT_LIST_HEAD(&hwreq->tds);
        }

        return (hwreq == NULL) ? NULL : &hwreq->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 ci_hw_ep  *hwep  = container_of(ep,  struct ci_hw_ep, ep);
        struct ci_hw_req *hwreq = container_of(req, struct ci_hw_req, req);
        struct td_node *node, *tmpnode;
        unsigned long flags;

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

        spin_lock_irqsave(hwep->lock, flags);

        list_for_each_entry_safe(node, tmpnode, &hwreq->tds, td) {
                dma_pool_free(hwep->td_pool, node->ptr, node->dma);
                list_del_init(&node->td);
                node->ptr = NULL;
                kfree(node);
        }

        kfree(hwreq);

        spin_unlock_irqrestore(hwep->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 ci_hw_ep  *hwep  = container_of(ep,  struct ci_hw_ep, ep);
        int retval = 0;
        unsigned long flags;

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

        spin_lock_irqsave(hwep->lock, flags);
        if (hwep->ci->gadget.speed == USB_SPEED_UNKNOWN) {
                spin_unlock_irqrestore(hwep->lock, flags);
                return 0;
        }
        retval = _ep_queue(ep, req, gfp_flags);
        spin_unlock_irqrestore(hwep->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 ci_hw_ep  *hwep  = container_of(ep,  struct ci_hw_ep, ep);
        struct ci_hw_req *hwreq = container_of(req, struct ci_hw_req, req);
        unsigned long flags;
        struct td_node *node, *tmpnode;

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

        spin_lock_irqsave(hwep->lock, flags);
        if (hwep->ci->gadget.speed != USB_SPEED_UNKNOWN)
                hw_ep_flush(hwep->ci, hwep->num, hwep->dir);

        list_for_each_entry_safe(node, tmpnode, &hwreq->tds, td) {
                dma_pool_free(hwep->td_pool, node->ptr, node->dma);
                list_del(&node->td);
                kfree(node);
        }

        /* pop request */
        list_del_init(&hwreq->queue);

        usb_gadget_unmap_request(&hwep->ci->gadget, req, hwep->dir);

        req->status = -ECONNRESET;

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

        spin_unlock_irqrestore(hwep->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)
{
        return _ep_set_halt(ep, value, true);
}

/*
 * 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 ci_hw_ep *hwep = container_of(ep, struct ci_hw_ep, ep);
        unsigned long flags;

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

        spin_lock_irqsave(hwep->lock, flags);
        hwep->wedge = 1;
        spin_unlock_irqrestore(hwep->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 ci_hw_ep *hwep = container_of(ep, struct ci_hw_ep, ep);
        unsigned long flags;

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

        spin_lock_irqsave(hwep->lock, flags);
        if (hwep->ci->gadget.speed == USB_SPEED_UNKNOWN) {
                spin_unlock_irqrestore(hwep->lock, flags);
                return;
        }

        hw_ep_flush(hwep->ci, hwep->num, hwep->dir);

        spin_unlock_irqrestore(hwep->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
 *****************************************************************************/
/*
 * ci_hdrc_gadget_connect: caller makes sure gadget driver is binded
 */
static void ci_hdrc_gadget_connect(struct usb_gadget *_gadget, int is_active)
{
        struct ci_hdrc *ci = container_of(_gadget, struct ci_hdrc, gadget);

        if (is_active) {
                pm_runtime_get_sync(ci->dev);
                hw_device_reset(ci);
                spin_lock_irq(&ci->lock);
                if (ci->driver) {
                        hw_device_state(ci, ci->ep0out->qh.dma);
                        usb_gadget_set_state(_gadget, USB_STATE_POWERED);
                        spin_unlock_irq(&ci->lock);
                        usb_udc_vbus_handler(_gadget, true);
                } else {
                        spin_unlock_irq(&ci->lock);
                }
        } else {
                usb_udc_vbus_handler(_gadget, false);
                if (ci->driver)
                        ci->driver->disconnect(&ci->gadget);
                hw_device_state(ci, 0);
                if (ci->platdata->notify_event)
                        ci->platdata->notify_event(ci,
                        CI_HDRC_CONTROLLER_STOPPED_EVENT);
                _gadget_stop_activity(&ci->gadget);
                pm_runtime_put_sync(ci->dev);
                usb_gadget_set_state(_gadget, USB_STATE_NOTATTACHED);
        }
}

static int ci_udc_vbus_session(struct usb_gadget *_gadget, int is_active)
{
        struct ci_hdrc *ci = container_of(_gadget, struct ci_hdrc, gadget);
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(&ci->lock, flags);
        ci->vbus_active = is_active;
        spin_unlock_irqrestore(&ci->lock, flags);

        if (ci->usb_phy)
                usb_phy_set_charger_state(ci->usb_phy, is_active ?
                        USB_CHARGER_PRESENT : USB_CHARGER_ABSENT);

        if (ci->platdata->notify_event)
                ret = ci->platdata->notify_event(ci,
                                CI_HDRC_CONTROLLER_VBUS_EVENT);

        if (ci->driver)
                ci_hdrc_gadget_connect(_gadget, is_active);

        return ret;
}

static int ci_udc_wakeup(struct usb_gadget *_gadget)
{
        struct ci_hdrc *ci = container_of(_gadget, struct ci_hdrc, gadget);
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(&ci->lock, flags);
        if (ci->gadget.speed == USB_SPEED_UNKNOWN) {
                spin_unlock_irqrestore(&ci->lock, flags);
                return 0;
        }
        if (!ci->remote_wakeup) {
                ret = -EOPNOTSUPP;
                goto out;
        }
        if (!hw_read(ci, OP_PORTSC, PORTSC_SUSP)) {
                ret = -EINVAL;
                goto out;
        }
        hw_write(ci, OP_PORTSC, PORTSC_FPR, PORTSC_FPR);
out:
        spin_unlock_irqrestore(&ci->lock, flags);
        return ret;
}

static int ci_udc_vbus_draw(struct usb_gadget *_gadget, unsigned ma)
{
        struct ci_hdrc *ci = container_of(_gadget, struct ci_hdrc, gadget);

        if (ci->usb_phy)
                return usb_phy_set_power(ci->usb_phy, ma);
        return -ENOTSUPP;
}

static int ci_udc_selfpowered(struct usb_gadget *_gadget, int is_on)
{
        struct ci_hdrc *ci = container_of(_gadget, struct ci_hdrc, gadget);
        struct ci_hw_ep *hwep = ci->ep0in;
        unsigned long flags;

        spin_lock_irqsave(hwep->lock, flags);
        _gadget->is_selfpowered = (is_on != 0);
        spin_unlock_irqrestore(hwep->lock, flags);

        return 0;
}

/* Change Data+ pullup status
 * this func is used by usb_gadget_connect/disconnect
 */
static int ci_udc_pullup(struct usb_gadget *_gadget, int is_on)
{
        struct ci_hdrc *ci = container_of(_gadget, struct ci_hdrc, gadget);

        /*
         * Data+ pullup controlled by OTG state machine in OTG fsm mode;
         * and don't touch Data+ in host mode for dual role config.
         */
        if (ci_otg_is_fsm_mode(ci) || ci->role == CI_ROLE_HOST)
                return 0;

        pm_runtime_get_sync(ci->dev);
        if (is_on)
                hw_write(ci, OP_USBCMD, USBCMD_RS, USBCMD_RS);
        else
                hw_write(ci, OP_USBCMD, USBCMD_RS, 0);
        pm_runtime_put_sync(ci->dev);

        return 0;
}

static int ci_udc_start(struct usb_gadget *gadget,
                         struct usb_gadget_driver *driver);
static int ci_udc_stop(struct usb_gadget *gadget);

/* Match ISOC IN from the highest endpoint */
static struct usb_ep *ci_udc_match_ep(struct usb_gadget *gadget,
                              struct usb_endpoint_descriptor *desc,
                              struct usb_ss_ep_comp_descriptor *comp_desc)
{
        struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget);
        struct usb_ep *ep;

        if (usb_endpoint_xfer_isoc(desc) && usb_endpoint_dir_in(desc)) {
                list_for_each_entry_reverse(ep, &ci->gadget.ep_list, ep_list) {
                        if (ep->caps.dir_in && !ep->claimed)
                                return ep;
                }
        }

        return NULL;
}

/*
 * 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   = ci_udc_vbus_session,
        .wakeup         = ci_udc_wakeup,
        .set_selfpowered        = ci_udc_selfpowered,
        .pullup         = ci_udc_pullup,
        .vbus_draw      = ci_udc_vbus_draw,
        .udc_start      = ci_udc_start,
        .udc_stop       = ci_udc_stop,
        .match_ep       = ci_udc_match_ep,
};

static int init_eps(struct ci_hdrc *ci)
{
        int retval = 0, i, j;

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

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

                        hwep->ci          = ci;
                        hwep->lock         = &ci->lock;
                        hwep->td_pool      = ci->td_pool;

                        hwep->ep.name      = hwep->name;
                        hwep->ep.ops       = &usb_ep_ops;

                        if (i == 0) {
                                hwep->ep.caps.type_control = true;
                        } else {
                                hwep->ep.caps.type_iso = true;
                                hwep->ep.caps.type_bulk = true;
                                hwep->ep.caps.type_int = true;
                        }

                        if (j == TX)
                                hwep->ep.caps.dir_in = true;
                        else
                                hwep->ep.caps.dir_out = true;

                        /*
                         * for ep0: maxP defined in desc, for other
                         * eps, maxP is set by epautoconfig() called
                         * by gadget layer
                         */
                        usb_ep_set_maxpacket_limit(&hwep->ep, (unsigned short)~0);

                        INIT_LIST_HEAD(&hwep->qh.queue);
                        hwep->qh.ptr = dma_pool_zalloc(ci->qh_pool, GFP_KERNEL,
                                                       &hwep->qh.dma);
                        if (hwep->qh.ptr == NULL)
                                retval = -ENOMEM;

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

                                usb_ep_set_maxpacket_limit(&hwep->ep, CTRL_PAYLOAD_MAX);
                                continue;
                        }

                        list_add_tail(&hwep->ep.ep_list, &ci->gadget.ep_list);
                }

        return retval;
}

static void destroy_eps(struct ci_hdrc *ci)
{
        int i;

        for (i = 0; i < ci->hw_ep_max; i++) {
                struct ci_hw_ep *hwep = &ci->ci_hw_ep[i];

                if (hwep->pending_td)
                        free_pending_td(hwep);
                dma_pool_free(ci->qh_pool, hwep->qh.ptr, hwep->qh.dma);
        }
}

/**
 * ci_udc_start: register a gadget driver
 * @gadget: our gadget
 * @driver: the driver being registered
 *
 * Interrupts are enabled here.
 */
static int ci_udc_start(struct usb_gadget *gadget,
                         struct usb_gadget_driver *driver)
{
        struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget);
        int retval;

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

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

        ci->ep0in->ep.desc = &ctrl_endpt_in_desc;
        retval = usb_ep_enable(&ci->ep0in->ep);
        if (retval)
                return retval;

        ci->driver = driver;

        /* Start otg fsm for B-device */
        if (ci_otg_is_fsm_mode(ci) && ci->fsm.id) {
                ci_hdrc_otg_fsm_start(ci);
                return retval;
        }

        if (ci->vbus_active)
                ci_hdrc_gadget_connect(gadget, 1);
        else
                usb_udc_vbus_handler(&ci->gadget, false);

        return retval;
}

static void ci_udc_stop_for_otg_fsm(struct ci_hdrc *ci)
{
        if (!ci_otg_is_fsm_mode(ci))
                return;

        mutex_lock(&ci->fsm.lock);
        if (ci->fsm.otg->state == OTG_STATE_A_PERIPHERAL) {
                ci->fsm.a_bidl_adis_tmout = 1;
                ci_hdrc_otg_fsm_start(ci);
        } else if (ci->fsm.otg->state == OTG_STATE_B_PERIPHERAL) {
                ci->fsm.protocol = PROTO_UNDEF;
                ci->fsm.otg->state = OTG_STATE_UNDEFINED;
        }
        mutex_unlock(&ci->fsm.lock);
}

/*
 * ci_udc_stop: unregister a gadget driver
 */
static int ci_udc_stop(struct usb_gadget *gadget)
{
        struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget);
        unsigned long flags;

        spin_lock_irqsave(&ci->lock, flags);
        ci->driver = NULL;

        if (ci->vbus_active) {
                hw_device_state(ci, 0);
                spin_unlock_irqrestore(&ci->lock, flags);
                if (ci->platdata->notify_event)
                        ci->platdata->notify_event(ci,
                        CI_HDRC_CONTROLLER_STOPPED_EVENT);
                _gadget_stop_activity(&ci->gadget);
                spin_lock_irqsave(&ci->lock, flags);
                pm_runtime_put(ci->dev);
        }

        spin_unlock_irqrestore(&ci->lock, flags);

        ci_udc_stop_for_otg_fsm(ci);
        return 0;
}

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

        if (ci == NULL)
                return IRQ_HANDLED;

        spin_lock(&ci->lock);

        if (ci->platdata->flags & CI_HDRC_REGS_SHARED) {
                if (hw_read(ci, OP_USBMODE, USBMODE_CM) !=
                                USBMODE_CM_DC) {
                        spin_unlock(&ci->lock);
                        return IRQ_NONE;
                }

        }
        intr = hw_test_and_clear_intr_active(ci);

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

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

                if (USBi_UI  & intr)
                        isr_tr_complete_handler(ci);

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

        return retval;
}

/**
 * udc_start: initialize gadget role
 * @ci: chipidea controller
 */
static int udc_start(struct ci_hdrc *ci)
{
        struct device *dev = ci->dev;
        struct usb_otg_caps *otg_caps = &ci->platdata->ci_otg_caps;
        int retval = 0;

        ci->gadget.ops          = &usb_gadget_ops;
        ci->gadget.speed        = USB_SPEED_UNKNOWN;
        ci->gadget.max_speed    = USB_SPEED_HIGH;
        ci->gadget.name         = ci->platdata->name;
        ci->gadget.otg_caps     = otg_caps;
        ci->gadget.sg_supported = 1;

        if (ci->platdata->flags & CI_HDRC_REQUIRES_ALIGNED_DMA)
                ci->gadget.quirk_avoids_skb_reserve = 1;

        if (ci->is_otg && (otg_caps->hnp_support || otg_caps->srp_support ||
                                                otg_caps->adp_support))
                ci->gadget.is_otg = 1;

        INIT_LIST_HEAD(&ci->gadget.ep_list);

        /* alloc resources */
        ci->qh_pool = dma_pool_create("ci_hw_qh", dev->parent,
                                       sizeof(struct ci_hw_qh),
                                       64, CI_HDRC_PAGE_SIZE);
        if (ci->qh_pool == NULL)
                return -ENOMEM;

        ci->td_pool = dma_pool_create("ci_hw_td", dev->parent,
                                       sizeof(struct ci_hw_td),
                                       64, CI_HDRC_PAGE_SIZE);
        if (ci->td_pool == NULL) {
                retval = -ENOMEM;
                goto free_qh_pool;
        }

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

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

        retval = usb_add_gadget_udc(dev, &ci->gadget);
        if (retval)
                goto destroy_eps;

        return retval;

destroy_eps:
        destroy_eps(ci);
free_pools:
        dma_pool_destroy(ci->td_pool);
free_qh_pool:
        dma_pool_destroy(ci->qh_pool);
        return retval;
}

/*
 * ci_hdrc_gadget_destroy: parent remove must call this to remove UDC
 *
 * No interrupts active, the IRQ has been released
 */
void ci_hdrc_gadget_destroy(struct ci_hdrc *ci)
{
        if (!ci->roles[CI_ROLE_GADGET])
                return;

        usb_del_gadget_udc(&ci->gadget);

        destroy_eps(ci);

        dma_pool_destroy(ci->td_pool);
        dma_pool_destroy(ci->qh_pool);
}

static int udc_id_switch_for_device(struct ci_hdrc *ci)
{
        if (ci->platdata->pins_device)
                pinctrl_select_state(ci->platdata->pctl,
                                     ci->platdata->pins_device);

        if (ci->is_otg)
                /* Clear and enable BSV irq */
                hw_write_otgsc(ci, OTGSC_BSVIS | OTGSC_BSVIE,
                                        OTGSC_BSVIS | OTGSC_BSVIE);

        return 0;
}

static void udc_id_switch_for_host(struct ci_hdrc *ci)
{
        /*
         * host doesn't care B_SESSION_VALID event
         * so clear and disbale BSV irq
         */
        if (ci->is_otg)
                hw_write_otgsc(ci, OTGSC_BSVIE | OTGSC_BSVIS, OTGSC_BSVIS);

        ci->vbus_active = 0;

        if (ci->platdata->pins_device && ci->platdata->pins_default)
                pinctrl_select_state(ci->platdata->pctl,
                                     ci->platdata->pins_default);
}

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

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

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

        rdrv->start     = udc_id_switch_for_device;
        rdrv->stop      = udc_id_switch_for_host;
        rdrv->irq       = udc_irq;
        rdrv->name      = "gadget";

        ret = udc_start(ci);
        if (!ret)
                ci->roles[CI_ROLE_GADGET] = rdrv;

        return ret;
}