// SPDX-License-Identifier: GPL-2.0
/* linux/drivers/usb/gadget/s3c-hsudc.c
 *
 * Copyright (c) 2010 Samsung Electronics Co., Ltd.
 *              http://www.samsung.com/
 *
 * S3C24XX USB 2.0 High-speed USB controller gadget driver
 *
 * The S3C24XX USB 2.0 high-speed USB controller supports upto 9 endpoints.
 * Each endpoint can be configured as either in or out endpoint. Endpoints
 * can be configured for Bulk or Interrupt transfer mode.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/otg.h>
#include <linux/prefetch.h>
#include <linux/platform_data/s3c-hsudc.h>
#include <linux/regulator/consumer.h>
#include <linux/pm_runtime.h>

#define S3C_HSUDC_REG(x)        (x)

/* Non-Indexed Registers */
#define S3C_IR                          S3C_HSUDC_REG(0x00) /* Index Register */
#define S3C_EIR                         S3C_HSUDC_REG(0x04) /* EP Intr Status */
#define S3C_EIR_EP0                     (1<<0)
#define S3C_EIER                        S3C_HSUDC_REG(0x08) /* EP Intr Enable */
#define S3C_FAR                         S3C_HSUDC_REG(0x0c) /* Gadget Address */
#define S3C_FNR                         S3C_HSUDC_REG(0x10) /* Frame Number */
#define S3C_EDR                         S3C_HSUDC_REG(0x14) /* EP Direction */
#define S3C_TR                          S3C_HSUDC_REG(0x18) /* Test Register */
#define S3C_SSR                         S3C_HSUDC_REG(0x1c) /* System Status */
#define S3C_SSR_DTZIEN_EN               (0xff8f)
#define S3C_SSR_ERR                     (0xff80)
#define S3C_SSR_VBUSON                  (1 << 8)
#define S3C_SSR_HSP                     (1 << 4)
#define S3C_SSR_SDE                     (1 << 3)
#define S3C_SSR_RESUME                  (1 << 2)
#define S3C_SSR_SUSPEND                 (1 << 1)
#define S3C_SSR_RESET                   (1 << 0)
#define S3C_SCR                         S3C_HSUDC_REG(0x20) /* System Control */
#define S3C_SCR_DTZIEN_EN               (1 << 14)
#define S3C_SCR_RRD_EN                  (1 << 5)
#define S3C_SCR_SUS_EN                  (1 << 1)
#define S3C_SCR_RST_EN                  (1 << 0)
#define S3C_EP0SR                       S3C_HSUDC_REG(0x24) /* EP0 Status */
#define S3C_EP0SR_EP0_LWO               (1 << 6)
#define S3C_EP0SR_STALL                 (1 << 4)
#define S3C_EP0SR_TX_SUCCESS            (1 << 1)
#define S3C_EP0SR_RX_SUCCESS            (1 << 0)
#define S3C_EP0CR                       S3C_HSUDC_REG(0x28) /* EP0 Control */
#define S3C_BR(_x)                      S3C_HSUDC_REG(0x60 + (_x * 4))

/* Indexed Registers */
#define S3C_ESR                         S3C_HSUDC_REG(0x2c) /* EPn Status */
#define S3C_ESR_FLUSH                   (1 << 6)
#define S3C_ESR_STALL                   (1 << 5)
#define S3C_ESR_LWO                     (1 << 4)
#define S3C_ESR_PSIF_ONE                (1 << 2)
#define S3C_ESR_PSIF_TWO                (2 << 2)
#define S3C_ESR_TX_SUCCESS              (1 << 1)
#define S3C_ESR_RX_SUCCESS              (1 << 0)
#define S3C_ECR                         S3C_HSUDC_REG(0x30) /* EPn Control */
#define S3C_ECR_DUEN                    (1 << 7)
#define S3C_ECR_FLUSH                   (1 << 6)
#define S3C_ECR_STALL                   (1 << 1)
#define S3C_ECR_IEMS                    (1 << 0)
#define S3C_BRCR                        S3C_HSUDC_REG(0x34) /* Read Count */
#define S3C_BWCR                        S3C_HSUDC_REG(0x38) /* Write Count */
#define S3C_MPR                         S3C_HSUDC_REG(0x3c) /* Max Pkt Size */

#define WAIT_FOR_SETUP                  (0)
#define DATA_STATE_XMIT                 (1)
#define DATA_STATE_RECV                 (2)

static const char * const s3c_hsudc_supply_names[] = {
        "vdda",         /* analog phy supply, 3.3V */
        "vddi",         /* digital phy supply, 1.2V */
        "vddosc",       /* oscillator supply, 1.8V - 3.3V */
};

/**
 * struct s3c_hsudc_ep - Endpoint representation used by driver.
 * @ep: USB gadget layer representation of device endpoint.
 * @name: Endpoint name (as required by ep autoconfiguration).
 * @dev: Reference to the device controller to which this EP belongs.
 * @desc: Endpoint descriptor obtained from the gadget driver.
 * @queue: Transfer request queue for the endpoint.
 * @stopped: Maintains state of endpoint, set if EP is halted.
 * @bEndpointAddress: EP address (including direction bit).
 * @fifo: Base address of EP FIFO.
 */
struct s3c_hsudc_ep {
        struct usb_ep ep;
        char name[20];
        struct s3c_hsudc *dev;
        struct list_head queue;
        u8 stopped;
        u8 wedge;
        u8 bEndpointAddress;
        void __iomem *fifo;
};

/**
 * struct s3c_hsudc_req - Driver encapsulation of USB gadget transfer request.
 * @req: Reference to USB gadget transfer request.
 * @queue: Used for inserting this request to the endpoint request queue.
 */
struct s3c_hsudc_req {
        struct usb_request req;
        struct list_head queue;
};

/**
 * struct s3c_hsudc - Driver's abstraction of the device controller.
 * @gadget: Instance of usb_gadget which is referenced by gadget driver.
 * @driver: Reference to currenty active gadget driver.
 * @dev: The device reference used by probe function.
 * @lock: Lock to synchronize the usage of Endpoints (EP's are indexed).
 * @regs: Remapped base address of controller's register space.
 * irq: IRQ number used by the controller.
 * uclk: Reference to the controller clock.
 * ep0state: Current state of EP0.
 * ep: List of endpoints supported by the controller.
 */
struct s3c_hsudc {
        struct usb_gadget gadget;
        struct usb_gadget_driver *driver;
        struct device *dev;
        struct s3c24xx_hsudc_platdata *pd;
        struct usb_phy *transceiver;
        struct regulator_bulk_data supplies[ARRAY_SIZE(s3c_hsudc_supply_names)];
        spinlock_t lock;
        void __iomem *regs;
        int irq;
        struct clk *uclk;
        int ep0state;
        struct s3c_hsudc_ep ep[];
};

#define ep_maxpacket(_ep)       ((_ep)->ep.maxpacket)
#define ep_is_in(_ep)           ((_ep)->bEndpointAddress & USB_DIR_IN)
#define ep_index(_ep)           ((_ep)->bEndpointAddress & \
                                        USB_ENDPOINT_NUMBER_MASK)

static const char driver_name[] = "s3c-udc";
static const char ep0name[] = "ep0-control";

static inline struct s3c_hsudc_req *our_req(struct usb_request *req)
{
        return container_of(req, struct s3c_hsudc_req, req);
}

static inline struct s3c_hsudc_ep *our_ep(struct usb_ep *ep)
{
        return container_of(ep, struct s3c_hsudc_ep, ep);
}

static inline struct s3c_hsudc *to_hsudc(struct usb_gadget *gadget)
{
        return container_of(gadget, struct s3c_hsudc, gadget);
}

static inline void set_index(struct s3c_hsudc *hsudc, int ep_addr)
{
        ep_addr &= USB_ENDPOINT_NUMBER_MASK;
        writel(ep_addr, hsudc->regs + S3C_IR);
}

static inline void __orr32(void __iomem *ptr, u32 val)
{
        writel(readl(ptr) | val, ptr);
}

/**
 * s3c_hsudc_complete_request - Complete a transfer request.
 * @hsep: Endpoint to which the request belongs.
 * @hsreq: Transfer request to be completed.
 * @status: Transfer completion status for the transfer request.
 */
static void s3c_hsudc_complete_request(struct s3c_hsudc_ep *hsep,
                                struct s3c_hsudc_req *hsreq, int status)
{
        unsigned int stopped = hsep->stopped;
        struct s3c_hsudc *hsudc = hsep->dev;

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

        if (!ep_index(hsep)) {
                hsudc->ep0state = WAIT_FOR_SETUP;
                hsep->bEndpointAddress &= ~USB_DIR_IN;
        }

        hsep->stopped = 1;
        spin_unlock(&hsudc->lock);
        usb_gadget_giveback_request(&hsep->ep, &hsreq->req);
        spin_lock(&hsudc->lock);
        hsep->stopped = stopped;
}

/**
 * s3c_hsudc_nuke_ep - Terminate all requests queued for a endpoint.
 * @hsep: Endpoint for which queued requests have to be terminated.
 * @status: Transfer completion status for the transfer request.
 */
static void s3c_hsudc_nuke_ep(struct s3c_hsudc_ep *hsep, int status)
{
        struct s3c_hsudc_req *hsreq;

        while (!list_empty(&hsep->queue)) {
                hsreq = list_entry(hsep->queue.next,
                                struct s3c_hsudc_req, queue);
                s3c_hsudc_complete_request(hsep, hsreq, status);
        }
}

/**
 * s3c_hsudc_stop_activity - Stop activity on all endpoints.
 * @hsudc: Device controller for which EP activity is to be stopped.
 *
 * All the endpoints are stopped and any pending transfer requests if any on
 * the endpoint are terminated.
 */
static void s3c_hsudc_stop_activity(struct s3c_hsudc *hsudc)
{
        struct s3c_hsudc_ep *hsep;
        int epnum;

        hsudc->gadget.speed = USB_SPEED_UNKNOWN;

        for (epnum = 0; epnum < hsudc->pd->epnum; epnum++) {
                hsep = &hsudc->ep[epnum];
                hsep->stopped = 1;
                s3c_hsudc_nuke_ep(hsep, -ESHUTDOWN);
        }
}

/**
 * s3c_hsudc_read_setup_pkt - Read the received setup packet from EP0 fifo.
 * @hsudc: Device controller from which setup packet is to be read.
 * @buf: The buffer into which the setup packet is read.
 *
 * The setup packet received in the EP0 fifo is read and stored into a
 * given buffer address.
 */

static void s3c_hsudc_read_setup_pkt(struct s3c_hsudc *hsudc, u16 *buf)
{
        int count;

        count = readl(hsudc->regs + S3C_BRCR);
        while (count--)
                *buf++ = (u16)readl(hsudc->regs + S3C_BR(0));

        writel(S3C_EP0SR_RX_SUCCESS, hsudc->regs + S3C_EP0SR);
}

/**
 * s3c_hsudc_write_fifo - Write next chunk of transfer data to EP fifo.
 * @hsep: Endpoint to which the data is to be written.
 * @hsreq: Transfer request from which the next chunk of data is written.
 *
 * Write the next chunk of data from a transfer request to the endpoint FIFO.
 * If the transfer request completes, 1 is returned, otherwise 0 is returned.
 */
static int s3c_hsudc_write_fifo(struct s3c_hsudc_ep *hsep,
                                struct s3c_hsudc_req *hsreq)
{
        u16 *buf;
        u32 max = ep_maxpacket(hsep);
        u32 count, length;
        bool is_last;
        void __iomem *fifo = hsep->fifo;

        buf = hsreq->req.buf + hsreq->req.actual;
        prefetch(buf);

        length = hsreq->req.length - hsreq->req.actual;
        length = min(length, max);
        hsreq->req.actual += length;

        writel(length, hsep->dev->regs + S3C_BWCR);
        for (count = 0; count < length; count += 2)
                writel(*buf++, fifo);

        if (count != max) {
                is_last = true;
        } else {
                if (hsreq->req.length != hsreq->req.actual || hsreq->req.zero)
                        is_last = false;
                else
                        is_last = true;
        }

        if (is_last) {
                s3c_hsudc_complete_request(hsep, hsreq, 0);
                return 1;
        }

        return 0;
}

/**
 * s3c_hsudc_read_fifo - Read the next chunk of data from EP fifo.
 * @hsep: Endpoint from which the data is to be read.
 * @hsreq: Transfer request to which the next chunk of data read is written.
 *
 * Read the next chunk of data from the endpoint FIFO and a write it to the
 * transfer request buffer. If the transfer request completes, 1 is returned,
 * otherwise 0 is returned.
 */
static int s3c_hsudc_read_fifo(struct s3c_hsudc_ep *hsep,
                                struct s3c_hsudc_req *hsreq)
{
        struct s3c_hsudc *hsudc = hsep->dev;
        u32 csr, offset;
        u16 *buf, word;
        u32 buflen, rcnt, rlen;
        void __iomem *fifo = hsep->fifo;
        u32 is_short = 0;

        offset = (ep_index(hsep)) ? S3C_ESR : S3C_EP0SR;
        csr = readl(hsudc->regs + offset);
        if (!(csr & S3C_ESR_RX_SUCCESS))
                return -EINVAL;

        buf = hsreq->req.buf + hsreq->req.actual;
        prefetchw(buf);
        buflen = hsreq->req.length - hsreq->req.actual;

        rcnt = readl(hsudc->regs + S3C_BRCR);
        rlen = (csr & S3C_ESR_LWO) ? (rcnt * 2 - 1) : (rcnt * 2);

        hsreq->req.actual += min(rlen, buflen);
        is_short = (rlen < hsep->ep.maxpacket);

        while (rcnt-- != 0) {
                word = (u16)readl(fifo);
                if (buflen) {
                        *buf++ = word;
                        buflen--;
                } else {
                        hsreq->req.status = -EOVERFLOW;
                }
        }

        writel(S3C_ESR_RX_SUCCESS, hsudc->regs + offset);

        if (is_short || hsreq->req.actual == hsreq->req.length) {
                s3c_hsudc_complete_request(hsep, hsreq, 0);
                return 1;
        }

        return 0;
}

/**
 * s3c_hsudc_epin_intr - Handle in-endpoint interrupt.
 * @hsudc - Device controller for which the interrupt is to be handled.
 * @ep_idx - Endpoint number on which an interrupt is pending.
 *
 * Handles interrupt for a in-endpoint. The interrupts that are handled are
 * stall and data transmit complete interrupt.
 */
static void s3c_hsudc_epin_intr(struct s3c_hsudc *hsudc, u32 ep_idx)
{
        struct s3c_hsudc_ep *hsep = &hsudc->ep[ep_idx];
        struct s3c_hsudc_req *hsreq;
        u32 csr;

        csr = readl(hsudc->regs + S3C_ESR);
        if (csr & S3C_ESR_STALL) {
                writel(S3C_ESR_STALL, hsudc->regs + S3C_ESR);
                return;
        }

        if (csr & S3C_ESR_TX_SUCCESS) {
                writel(S3C_ESR_TX_SUCCESS, hsudc->regs + S3C_ESR);
                if (list_empty(&hsep->queue))
                        return;

                hsreq = list_entry(hsep->queue.next,
                                struct s3c_hsudc_req, queue);
                if ((s3c_hsudc_write_fifo(hsep, hsreq) == 0) &&
                                (csr & S3C_ESR_PSIF_TWO))
                        s3c_hsudc_write_fifo(hsep, hsreq);
        }
}

/**
 * s3c_hsudc_epout_intr - Handle out-endpoint interrupt.
 * @hsudc - Device controller for which the interrupt is to be handled.
 * @ep_idx - Endpoint number on which an interrupt is pending.
 *
 * Handles interrupt for a out-endpoint. The interrupts that are handled are
 * stall, flush and data ready interrupt.
 */
static void s3c_hsudc_epout_intr(struct s3c_hsudc *hsudc, u32 ep_idx)
{
        struct s3c_hsudc_ep *hsep = &hsudc->ep[ep_idx];
        struct s3c_hsudc_req *hsreq;
        u32 csr;

        csr = readl(hsudc->regs + S3C_ESR);
        if (csr & S3C_ESR_STALL) {
                writel(S3C_ESR_STALL, hsudc->regs + S3C_ESR);
                return;
        }

        if (csr & S3C_ESR_FLUSH) {
                __orr32(hsudc->regs + S3C_ECR, S3C_ECR_FLUSH);
                return;
        }

        if (csr & S3C_ESR_RX_SUCCESS) {
                if (list_empty(&hsep->queue))
                        return;

                hsreq = list_entry(hsep->queue.next,
                                struct s3c_hsudc_req, queue);
                if (((s3c_hsudc_read_fifo(hsep, hsreq)) == 0) &&
                                (csr & S3C_ESR_PSIF_TWO))
                        s3c_hsudc_read_fifo(hsep, hsreq);
        }
}

/** s3c_hsudc_set_halt - Set or clear a endpoint halt.
 * @_ep: Endpoint on which halt has to be set or cleared.
 * @value: 1 for setting halt on endpoint, 0 to clear halt.
 *
 * Set or clear endpoint halt. If halt is set, the endpoint is stopped.
 * If halt is cleared, for in-endpoints, if there are any pending
 * transfer requests, transfers are started.
 */
static int s3c_hsudc_set_halt(struct usb_ep *_ep, int value)
{
        struct s3c_hsudc_ep *hsep = our_ep(_ep);
        struct s3c_hsudc *hsudc = hsep->dev;
        struct s3c_hsudc_req *hsreq;
        unsigned long irqflags;
        u32 ecr;
        u32 offset;

        if (value && ep_is_in(hsep) && !list_empty(&hsep->queue))
                return -EAGAIN;

        spin_lock_irqsave(&hsudc->lock, irqflags);
        set_index(hsudc, ep_index(hsep));
        offset = (ep_index(hsep)) ? S3C_ECR : S3C_EP0CR;
        ecr = readl(hsudc->regs + offset);

        if (value) {
                ecr |= S3C_ECR_STALL;
                if (ep_index(hsep))
                        ecr |= S3C_ECR_FLUSH;
                hsep->stopped = 1;
        } else {
                ecr &= ~S3C_ECR_STALL;
                hsep->stopped = hsep->wedge = 0;
        }
        writel(ecr, hsudc->regs + offset);

        if (ep_is_in(hsep) && !list_empty(&hsep->queue) && !value) {
                hsreq = list_entry(hsep->queue.next,
                        struct s3c_hsudc_req, queue);
                if (hsreq)
                        s3c_hsudc_write_fifo(hsep, hsreq);
        }

        spin_unlock_irqrestore(&hsudc->lock, irqflags);
        return 0;
}

/** s3c_hsudc_set_wedge - Sets the halt feature with the clear requests ignored
 * @_ep: Endpoint on which wedge has to be set.
 *
 * Sets the halt feature with the clear requests ignored.
 */
static int s3c_hsudc_set_wedge(struct usb_ep *_ep)
{
        struct s3c_hsudc_ep *hsep = our_ep(_ep);

        if (!hsep)
                return -EINVAL;

        hsep->wedge = 1;
        return usb_ep_set_halt(_ep);
}

/** s3c_hsudc_handle_reqfeat - Handle set feature or clear feature requests.
 * @_ep: Device controller on which the set/clear feature needs to be handled.
 * @ctrl: Control request as received on the endpoint 0.
 *
 * Handle set feature or clear feature control requests on the control endpoint.
 */
static int s3c_hsudc_handle_reqfeat(struct s3c_hsudc *hsudc,
                                        struct usb_ctrlrequest *ctrl)
{
        struct s3c_hsudc_ep *hsep;
        bool set = (ctrl->bRequest == USB_REQ_SET_FEATURE);
        u8 ep_num = ctrl->wIndex & USB_ENDPOINT_NUMBER_MASK;

        if (ctrl->bRequestType == USB_RECIP_ENDPOINT) {
                hsep = &hsudc->ep[ep_num];
                switch (le16_to_cpu(ctrl->wValue)) {
                case USB_ENDPOINT_HALT:
                        if (set || !hsep->wedge)
                                s3c_hsudc_set_halt(&hsep->ep, set);
                        return 0;
                }
        }

        return -ENOENT;
}

/**
 * s3c_hsudc_process_req_status - Handle get status control request.
 * @hsudc: Device controller on which get status request has be handled.
 * @ctrl: Control request as received on the endpoint 0.
 *
 * Handle get status control request received on control endpoint.
 */
static void s3c_hsudc_process_req_status(struct s3c_hsudc *hsudc,
                                        struct usb_ctrlrequest *ctrl)
{
        struct s3c_hsudc_ep *hsep0 = &hsudc->ep[0];
        struct s3c_hsudc_req hsreq;
        struct s3c_hsudc_ep *hsep;
        __le16 reply;
        u8 epnum;

        switch (ctrl->bRequestType & USB_RECIP_MASK) {
        case USB_RECIP_DEVICE:
                reply = cpu_to_le16(0);
                break;

        case USB_RECIP_INTERFACE:
                reply = cpu_to_le16(0);
                break;

        case USB_RECIP_ENDPOINT:
                epnum = le16_to_cpu(ctrl->wIndex) & USB_ENDPOINT_NUMBER_MASK;
                hsep = &hsudc->ep[epnum];
                reply = cpu_to_le16(hsep->stopped ? 1 : 0);
                break;
        }

        INIT_LIST_HEAD(&hsreq.queue);
        hsreq.req.length = 2;
        hsreq.req.buf = &reply;
        hsreq.req.actual = 0;
        hsreq.req.complete = NULL;
        s3c_hsudc_write_fifo(hsep0, &hsreq);
}

/**
 * s3c_hsudc_process_setup - Process control request received on endpoint 0.
 * @hsudc: Device controller on which control request has been received.
 *
 * Read the control request received on endpoint 0, decode it and handle
 * the request.
 */
static void s3c_hsudc_process_setup(struct s3c_hsudc *hsudc)
{
        struct s3c_hsudc_ep *hsep = &hsudc->ep[0];
        struct usb_ctrlrequest ctrl = {0};
        int ret;

        s3c_hsudc_nuke_ep(hsep, -EPROTO);
        s3c_hsudc_read_setup_pkt(hsudc, (u16 *)&ctrl);

        if (ctrl.bRequestType & USB_DIR_IN) {
                hsep->bEndpointAddress |= USB_DIR_IN;
                hsudc->ep0state = DATA_STATE_XMIT;
        } else {
                hsep->bEndpointAddress &= ~USB_DIR_IN;
                hsudc->ep0state = DATA_STATE_RECV;
        }

        switch (ctrl.bRequest) {
        case USB_REQ_SET_ADDRESS:
                if (ctrl.bRequestType != (USB_TYPE_STANDARD | USB_RECIP_DEVICE))
                        break;
                hsudc->ep0state = WAIT_FOR_SETUP;
                return;

        case USB_REQ_GET_STATUS:
                if ((ctrl.bRequestType & USB_TYPE_MASK) != USB_TYPE_STANDARD)
                        break;
                s3c_hsudc_process_req_status(hsudc, &ctrl);
                return;

        case USB_REQ_SET_FEATURE:
        case USB_REQ_CLEAR_FEATURE:
                if ((ctrl.bRequestType & USB_TYPE_MASK) != USB_TYPE_STANDARD)
                        break;
                s3c_hsudc_handle_reqfeat(hsudc, &ctrl);
                hsudc->ep0state = WAIT_FOR_SETUP;
                return;
        }

        if (hsudc->driver) {
                spin_unlock(&hsudc->lock);
                ret = hsudc->driver->setup(&hsudc->gadget, &ctrl);
                spin_lock(&hsudc->lock);

                if (ctrl.bRequest == USB_REQ_SET_CONFIGURATION) {
                        hsep->bEndpointAddress &= ~USB_DIR_IN;
                        hsudc->ep0state = WAIT_FOR_SETUP;
                }

                if (ret < 0) {
                        dev_err(hsudc->dev, "setup failed, returned %d\n",
                                                ret);
                        s3c_hsudc_set_halt(&hsep->ep, 1);
                        hsudc->ep0state = WAIT_FOR_SETUP;
                        hsep->bEndpointAddress &= ~USB_DIR_IN;
                }
        }
}

/** s3c_hsudc_handle_ep0_intr - Handle endpoint 0 interrupt.
 * @hsudc: Device controller on which endpoint 0 interrupt has occured.
 *
 * Handle endpoint 0 interrupt when it occurs. EP0 interrupt could occur
 * when a stall handshake is sent to host or data is sent/received on
 * endpoint 0.
 */
static void s3c_hsudc_handle_ep0_intr(struct s3c_hsudc *hsudc)
{
        struct s3c_hsudc_ep *hsep = &hsudc->ep[0];
        struct s3c_hsudc_req *hsreq;
        u32 csr = readl(hsudc->regs + S3C_EP0SR);
        u32 ecr;

        if (csr & S3C_EP0SR_STALL) {
                ecr = readl(hsudc->regs + S3C_EP0CR);
                ecr &= ~(S3C_ECR_STALL | S3C_ECR_FLUSH);
                writel(ecr, hsudc->regs + S3C_EP0CR);

                writel(S3C_EP0SR_STALL, hsudc->regs + S3C_EP0SR);
                hsep->stopped = 0;

                s3c_hsudc_nuke_ep(hsep, -ECONNABORTED);
                hsudc->ep0state = WAIT_FOR_SETUP;
                hsep->bEndpointAddress &= ~USB_DIR_IN;
                return;
        }

        if (csr & S3C_EP0SR_TX_SUCCESS) {
                writel(S3C_EP0SR_TX_SUCCESS, hsudc->regs + S3C_EP0SR);
                if (ep_is_in(hsep)) {
                        if (list_empty(&hsep->queue))
                                return;

                        hsreq = list_entry(hsep->queue.next,
                                        struct s3c_hsudc_req, queue);
                        s3c_hsudc_write_fifo(hsep, hsreq);
                }
        }

        if (csr & S3C_EP0SR_RX_SUCCESS) {
                if (hsudc->ep0state == WAIT_FOR_SETUP)
                        s3c_hsudc_process_setup(hsudc);
                else {
                        if (!ep_is_in(hsep)) {
                                if (list_empty(&hsep->queue))
                                        return;
                                hsreq = list_entry(hsep->queue.next,
                                        struct s3c_hsudc_req, queue);
                                s3c_hsudc_read_fifo(hsep, hsreq);
                        }
                }
        }
}

/**
 * s3c_hsudc_ep_enable - Enable a endpoint.
 * @_ep: The endpoint to be enabled.
 * @desc: Endpoint descriptor.
 *
 * Enables a endpoint when called from the gadget driver. Endpoint stall if
 * any is cleared, transfer type is configured and endpoint interrupt is
 * enabled.
 */
static int s3c_hsudc_ep_enable(struct usb_ep *_ep,
                                const struct usb_endpoint_descriptor *desc)
{
        struct s3c_hsudc_ep *hsep;
        struct s3c_hsudc *hsudc;
        unsigned long flags;
        u32 ecr = 0;

        hsep = our_ep(_ep);
        if (!_ep || !desc || _ep->name == ep0name
                || desc->bDescriptorType != USB_DT_ENDPOINT
                || hsep->bEndpointAddress != desc->bEndpointAddress
                || ep_maxpacket(hsep) < usb_endpoint_maxp(desc))
                return -EINVAL;

        if ((desc->bmAttributes == USB_ENDPOINT_XFER_BULK
                && usb_endpoint_maxp(desc) != ep_maxpacket(hsep))
                || !desc->wMaxPacketSize)
                return -ERANGE;

        hsudc = hsep->dev;
        if (!hsudc->driver || hsudc->gadget.speed == USB_SPEED_UNKNOWN)
                return -ESHUTDOWN;

        spin_lock_irqsave(&hsudc->lock, flags);

        set_index(hsudc, hsep->bEndpointAddress);
        ecr |= ((usb_endpoint_xfer_int(desc)) ? S3C_ECR_IEMS : S3C_ECR_DUEN);
        writel(ecr, hsudc->regs + S3C_ECR);

        hsep->stopped = hsep->wedge = 0;
        hsep->ep.desc = desc;
        hsep->ep.maxpacket = usb_endpoint_maxp(desc);

        s3c_hsudc_set_halt(_ep, 0);
        __set_bit(ep_index(hsep), hsudc->regs + S3C_EIER);

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

/**
 * s3c_hsudc_ep_disable - Disable a endpoint.
 * @_ep: The endpoint to be disabled.
 * @desc: Endpoint descriptor.
 *
 * Disables a endpoint when called from the gadget driver.
 */
static int s3c_hsudc_ep_disable(struct usb_ep *_ep)
{
        struct s3c_hsudc_ep *hsep = our_ep(_ep);
        struct s3c_hsudc *hsudc = hsep->dev;
        unsigned long flags;

        if (!_ep || !hsep->ep.desc)
                return -EINVAL;

        spin_lock_irqsave(&hsudc->lock, flags);

        set_index(hsudc, hsep->bEndpointAddress);
        __clear_bit(ep_index(hsep), hsudc->regs + S3C_EIER);

        s3c_hsudc_nuke_ep(hsep, -ESHUTDOWN);

        hsep->ep.desc = NULL;
        hsep->stopped = 1;

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

/**
 * s3c_hsudc_alloc_request - Allocate a new request.
 * @_ep: Endpoint for which request is allocated (not used).
 * @gfp_flags: Flags used for the allocation.
 *
 * Allocates a single transfer request structure when called from gadget driver.
 */
static struct usb_request *s3c_hsudc_alloc_request(struct usb_ep *_ep,
                                                gfp_t gfp_flags)
{
        struct s3c_hsudc_req *hsreq;

        hsreq = kzalloc(sizeof(*hsreq), gfp_flags);
        if (!hsreq)
                return NULL;

        INIT_LIST_HEAD(&hsreq->queue);
        return &hsreq->req;
}

/**
 * s3c_hsudc_free_request - Deallocate a request.
 * @ep: Endpoint for which request is deallocated (not used).
 * @_req: Request to be deallocated.
 *
 * Allocates a single transfer request structure when called from gadget driver.
 */
static void s3c_hsudc_free_request(struct usb_ep *ep, struct usb_request *_req)
{
        struct s3c_hsudc_req *hsreq;

        hsreq = our_req(_req);
        WARN_ON(!list_empty(&hsreq->queue));
        kfree(hsreq);
}

/**
 * s3c_hsudc_queue - Queue a transfer request for the endpoint.
 * @_ep: Endpoint for which the request is queued.
 * @_req: Request to be queued.
 * @gfp_flags: Not used.
 *
 * Start or enqueue a request for a endpoint when called from gadget driver.
 */
static int s3c_hsudc_queue(struct usb_ep *_ep, struct usb_request *_req,
                        gfp_t gfp_flags)
{
        struct s3c_hsudc_req *hsreq;
        struct s3c_hsudc_ep *hsep;
        struct s3c_hsudc *hsudc;
        unsigned long flags;
        u32 offset;
        u32 csr;

        hsreq = our_req(_req);
        if ((!_req || !_req->complete || !_req->buf ||
                !list_empty(&hsreq->queue)))
                return -EINVAL;

        hsep = our_ep(_ep);
        hsudc = hsep->dev;
        if (!hsudc->driver || hsudc->gadget.speed == USB_SPEED_UNKNOWN)
                return -ESHUTDOWN;

        spin_lock_irqsave(&hsudc->lock, flags);
        set_index(hsudc, hsep->bEndpointAddress);

        _req->status = -EINPROGRESS;
        _req->actual = 0;

        if (!ep_index(hsep) && _req->length == 0) {
                hsudc->ep0state = WAIT_FOR_SETUP;
                s3c_hsudc_complete_request(hsep, hsreq, 0);
                spin_unlock_irqrestore(&hsudc->lock, flags);
                return 0;
        }

        if (list_empty(&hsep->queue) && !hsep->stopped) {
                offset = (ep_index(hsep)) ? S3C_ESR : S3C_EP0SR;
                if (ep_is_in(hsep)) {
                        csr = readl(hsudc->regs + offset);
                        if (!(csr & S3C_ESR_TX_SUCCESS) &&
                                (s3c_hsudc_write_fifo(hsep, hsreq) == 1))
                                hsreq = NULL;
                } else {
                        csr = readl(hsudc->regs + offset);
                        if ((csr & S3C_ESR_RX_SUCCESS)
                                   && (s3c_hsudc_read_fifo(hsep, hsreq) == 1))
                                hsreq = NULL;
                }
        }

        if (hsreq)
                list_add_tail(&hsreq->queue, &hsep->queue);

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

/**
 * s3c_hsudc_dequeue - Dequeue a transfer request from an endpoint.
 * @_ep: Endpoint from which the request is dequeued.
 * @_req: Request to be dequeued.
 *
 * Dequeue a request from a endpoint when called from gadget driver.
 */
static int s3c_hsudc_dequeue(struct usb_ep *_ep, struct usb_request *_req)
{
        struct s3c_hsudc_ep *hsep = our_ep(_ep);
        struct s3c_hsudc *hsudc = hsep->dev;
        struct s3c_hsudc_req *hsreq;
        unsigned long flags;

        hsep = our_ep(_ep);
        if (!_ep || hsep->ep.name == ep0name)
                return -EINVAL;

        spin_lock_irqsave(&hsudc->lock, flags);

        list_for_each_entry(hsreq, &hsep->queue, queue) {
                if (&hsreq->req == _req)
                        break;
        }
        if (&hsreq->req != _req) {
                spin_unlock_irqrestore(&hsudc->lock, flags);
                return -EINVAL;
        }

        set_index(hsudc, hsep->bEndpointAddress);
        s3c_hsudc_complete_request(hsep, hsreq, -ECONNRESET);

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

static const struct usb_ep_ops s3c_hsudc_ep_ops = {
        .enable = s3c_hsudc_ep_enable,
        .disable = s3c_hsudc_ep_disable,
        .alloc_request = s3c_hsudc_alloc_request,
        .free_request = s3c_hsudc_free_request,
        .queue = s3c_hsudc_queue,
        .dequeue = s3c_hsudc_dequeue,
        .set_halt = s3c_hsudc_set_halt,
        .set_wedge = s3c_hsudc_set_wedge,
};

/**
 * s3c_hsudc_initep - Initialize a endpoint to default state.
 * @hsudc - Reference to the device controller.
 * @hsep - Endpoint to be initialized.
 * @epnum - Address to be assigned to the endpoint.
 *
 * Initialize a endpoint with default configuration.
 */
static void s3c_hsudc_initep(struct s3c_hsudc *hsudc,
                                struct s3c_hsudc_ep *hsep, int epnum)
{
        char *dir;

        if ((epnum % 2) == 0) {
                dir = "out";
        } else {
                dir = "in";
                hsep->bEndpointAddress = USB_DIR_IN;
        }

        hsep->bEndpointAddress |= epnum;
        if (epnum)
                snprintf(hsep->name, sizeof(hsep->name), "ep%d%s", epnum, dir);
        else
                snprintf(hsep->name, sizeof(hsep->name), "%s", ep0name);

        INIT_LIST_HEAD(&hsep->queue);
        INIT_LIST_HEAD(&hsep->ep.ep_list);
        if (epnum)
                list_add_tail(&hsep->ep.ep_list, &hsudc->gadget.ep_list);

        hsep->dev = hsudc;
        hsep->ep.name = hsep->name;
        usb_ep_set_maxpacket_limit(&hsep->ep, epnum ? 512 : 64);
        hsep->ep.ops = &s3c_hsudc_ep_ops;
        hsep->fifo = hsudc->regs + S3C_BR(epnum);
        hsep->ep.desc = NULL;
        hsep->stopped = 0;
        hsep->wedge = 0;

        if (epnum == 0) {
                hsep->ep.caps.type_control = true;
                hsep->ep.caps.dir_in = true;
                hsep->ep.caps.dir_out = true;
        } else {
                hsep->ep.caps.type_iso = true;
                hsep->ep.caps.type_bulk = true;
                hsep->ep.caps.type_int = true;
        }

        if (epnum & 1)
                hsep->ep.caps.dir_in = true;
        else
                hsep->ep.caps.dir_out = true;

        set_index(hsudc, epnum);
        writel(hsep->ep.maxpacket, hsudc->regs + S3C_MPR);
}

/**
 * s3c_hsudc_setup_ep - Configure all endpoints to default state.
 * @hsudc: Reference to device controller.
 *
 * Configures all endpoints to default state.
 */
static void s3c_hsudc_setup_ep(struct s3c_hsudc *hsudc)
{
        int epnum;

        hsudc->ep0state = WAIT_FOR_SETUP;
        INIT_LIST_HEAD(&hsudc->gadget.ep_list);
        for (epnum = 0; epnum < hsudc->pd->epnum; epnum++)
                s3c_hsudc_initep(hsudc, &hsudc->ep[epnum], epnum);
}

/**
 * s3c_hsudc_reconfig - Reconfigure the device controller to default state.
 * @hsudc: Reference to device controller.
 *
 * Reconfigures the device controller registers to a default state.
 */
static void s3c_hsudc_reconfig(struct s3c_hsudc *hsudc)
{
        writel(0xAA, hsudc->regs + S3C_EDR);
        writel(1, hsudc->regs + S3C_EIER);

        writel(0, hsudc->regs + S3C_TR);
        writel(S3C_SCR_DTZIEN_EN | S3C_SCR_RRD_EN | S3C_SCR_SUS_EN |
                        S3C_SCR_RST_EN, hsudc->regs + S3C_SCR);
        writel(0, hsudc->regs + S3C_EP0CR);

        s3c_hsudc_setup_ep(hsudc);
}

/**
 * s3c_hsudc_irq - Interrupt handler for device controller.
 * @irq: Not used.
 * @_dev: Reference to the device controller.
 *
 * Interrupt handler for the device controller. This handler handles controller
 * interrupts and endpoint interrupts.
 */
static irqreturn_t s3c_hsudc_irq(int irq, void *_dev)
{
        struct s3c_hsudc *hsudc = _dev;
        struct s3c_hsudc_ep *hsep;
        u32 ep_intr;
        u32 sys_status;
        u32 ep_idx;

        spin_lock(&hsudc->lock);

        sys_status = readl(hsudc->regs + S3C_SSR);
        ep_intr = readl(hsudc->regs + S3C_EIR) & 0x3FF;

        if (!ep_intr && !(sys_status & S3C_SSR_DTZIEN_EN)) {
                spin_unlock(&hsudc->lock);
                return IRQ_HANDLED;
        }

        if (sys_status) {
                if (sys_status & S3C_SSR_VBUSON)
                        writel(S3C_SSR_VBUSON, hsudc->regs + S3C_SSR);

                if (sys_status & S3C_SSR_ERR)
                        writel(S3C_SSR_ERR, hsudc->regs + S3C_SSR);

                if (sys_status & S3C_SSR_SDE) {
                        writel(S3C_SSR_SDE, hsudc->regs + S3C_SSR);
                        hsudc->gadget.speed = (sys_status & S3C_SSR_HSP) ?
                                USB_SPEED_HIGH : USB_SPEED_FULL;
                }

                if (sys_status & S3C_SSR_SUSPEND) {
                        writel(S3C_SSR_SUSPEND, hsudc->regs + S3C_SSR);
                        if (hsudc->gadget.speed != USB_SPEED_UNKNOWN
                                && hsudc->driver && hsudc->driver->suspend)
                                hsudc->driver->suspend(&hsudc->gadget);
                }

                if (sys_status & S3C_SSR_RESUME) {
                        writel(S3C_SSR_RESUME, hsudc->regs + S3C_SSR);
                        if (hsudc->gadget.speed != USB_SPEED_UNKNOWN
                                && hsudc->driver && hsudc->driver->resume)
                                hsudc->driver->resume(&hsudc->gadget);
                }

                if (sys_status & S3C_SSR_RESET) {
                        writel(S3C_SSR_RESET, hsudc->regs + S3C_SSR);
                        for (ep_idx = 0; ep_idx < hsudc->pd->epnum; ep_idx++) {
                                hsep = &hsudc->ep[ep_idx];
                                hsep->stopped = 1;
                                s3c_hsudc_nuke_ep(hsep, -ECONNRESET);
                        }
                        s3c_hsudc_reconfig(hsudc);
                        hsudc->ep0state = WAIT_FOR_SETUP;
                }
        }

        if (ep_intr & S3C_EIR_EP0) {
                writel(S3C_EIR_EP0, hsudc->regs + S3C_EIR);
                set_index(hsudc, 0);
                s3c_hsudc_handle_ep0_intr(hsudc);
        }

        ep_intr >>= 1;
        ep_idx = 1;
        while (ep_intr) {
                if (ep_intr & 1)  {
                        hsep = &hsudc->ep[ep_idx];
                        set_index(hsudc, ep_idx);
                        writel(1 << ep_idx, hsudc->regs + S3C_EIR);
                        if (ep_is_in(hsep))
                                s3c_hsudc_epin_intr(hsudc, ep_idx);
                        else
                                s3c_hsudc_epout_intr(hsudc, ep_idx);
                }
                ep_intr >>= 1;
                ep_idx++;
        }

        spin_unlock(&hsudc->lock);
        return IRQ_HANDLED;
}

static int s3c_hsudc_start(struct usb_gadget *gadget,
                struct usb_gadget_driver *driver)
{
        struct s3c_hsudc *hsudc = to_hsudc(gadget);
        int ret;

        if (!driver
                || driver->max_speed < USB_SPEED_FULL
                || !driver->setup)
                return -EINVAL;

        if (!hsudc)
                return -ENODEV;

        if (hsudc->driver)
                return -EBUSY;

        hsudc->driver = driver;

        ret = regulator_bulk_enable(ARRAY_SIZE(hsudc->supplies),
                                    hsudc->supplies);
        if (ret != 0) {
                dev_err(hsudc->dev, "failed to enable supplies: %d\n", ret);
                goto err_supplies;
        }

        /* connect to bus through transceiver */
        if (!IS_ERR_OR_NULL(hsudc->transceiver)) {
                ret = otg_set_peripheral(hsudc->transceiver->otg,
                                        &hsudc->gadget);
                if (ret) {
                        dev_err(hsudc->dev, "%s: can't bind to transceiver\n",
                                        hsudc->gadget.name);
                        goto err_otg;
                }
        }

        enable_irq(hsudc->irq);
        s3c_hsudc_reconfig(hsudc);

        pm_runtime_get_sync(hsudc->dev);

        if (hsudc->pd->phy_init)
                hsudc->pd->phy_init();
        if (hsudc->pd->gpio_init)
                hsudc->pd->gpio_init();

        return 0;
err_otg:
        regulator_bulk_disable(ARRAY_SIZE(hsudc->supplies), hsudc->supplies);
err_supplies:
        hsudc->driver = NULL;
        return ret;
}

static int s3c_hsudc_stop(struct usb_gadget *gadget)
{
        struct s3c_hsudc *hsudc = to_hsudc(gadget);
        unsigned long flags;

        if (!hsudc)
                return -ENODEV;

        spin_lock_irqsave(&hsudc->lock, flags);
        hsudc->gadget.speed = USB_SPEED_UNKNOWN;
        if (hsudc->pd->phy_uninit)
                hsudc->pd->phy_uninit();

        pm_runtime_put(hsudc->dev);

        if (hsudc->pd->gpio_uninit)
                hsudc->pd->gpio_uninit();
        s3c_hsudc_stop_activity(hsudc);
        spin_unlock_irqrestore(&hsudc->lock, flags);

        if (!IS_ERR_OR_NULL(hsudc->transceiver))
                (void) otg_set_peripheral(hsudc->transceiver->otg, NULL);

        disable_irq(hsudc->irq);

        regulator_bulk_disable(ARRAY_SIZE(hsudc->supplies), hsudc->supplies);
        hsudc->driver = NULL;

        return 0;
}

static inline u32 s3c_hsudc_read_frameno(struct s3c_hsudc *hsudc)
{
        return readl(hsudc->regs + S3C_FNR) & 0x3FF;
}

static int s3c_hsudc_gadget_getframe(struct usb_gadget *gadget)
{
        return s3c_hsudc_read_frameno(to_hsudc(gadget));
}

static int s3c_hsudc_vbus_draw(struct usb_gadget *gadget, unsigned mA)
{
        struct s3c_hsudc *hsudc = to_hsudc(gadget);

        if (!hsudc)
                return -ENODEV;

        if (!IS_ERR_OR_NULL(hsudc->transceiver))
                return usb_phy_set_power(hsudc->transceiver, mA);

        return -EOPNOTSUPP;
}

static const struct usb_gadget_ops s3c_hsudc_gadget_ops = {
        .get_frame      = s3c_hsudc_gadget_getframe,
        .udc_start      = s3c_hsudc_start,
        .udc_stop       = s3c_hsudc_stop,
        .vbus_draw      = s3c_hsudc_vbus_draw,
};

static int s3c_hsudc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct s3c_hsudc *hsudc;
        struct s3c24xx_hsudc_platdata *pd = dev_get_platdata(&pdev->dev);
        int ret, i;

        hsudc = devm_kzalloc(&pdev->dev, struct_size(hsudc, ep, pd->epnum),
                             GFP_KERNEL);
        if (!hsudc)
                return -ENOMEM;

        platform_set_drvdata(pdev, dev);
        hsudc->dev = dev;
        hsudc->pd = dev_get_platdata(&pdev->dev);

        hsudc->transceiver = usb_get_phy(USB_PHY_TYPE_USB2);

        for (i = 0; i < ARRAY_SIZE(hsudc->supplies); i++)
                hsudc->supplies[i].supply = s3c_hsudc_supply_names[i];

        ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(hsudc->supplies),
                                 hsudc->supplies);
        if (ret != 0) {
                if (ret != -EPROBE_DEFER)
                        dev_err(dev, "failed to request supplies: %d\n", ret);
                goto err_supplies;
        }

        hsudc->regs = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(hsudc->regs)) {
                ret = PTR_ERR(hsudc->regs);
                goto err_res;
        }

        spin_lock_init(&hsudc->lock);

        hsudc->gadget.max_speed = USB_SPEED_HIGH;
        hsudc->gadget.ops = &s3c_hsudc_gadget_ops;
        hsudc->gadget.name = dev_name(dev);
        hsudc->gadget.ep0 = &hsudc->ep[0].ep;
        hsudc->gadget.is_otg = 0;
        hsudc->gadget.is_a_peripheral = 0;
        hsudc->gadget.speed = USB_SPEED_UNKNOWN;

        s3c_hsudc_setup_ep(hsudc);

        ret = platform_get_irq(pdev, 0);
        if (ret < 0)
                goto err_res;
        hsudc->irq = ret;

        ret = devm_request_irq(&pdev->dev, hsudc->irq, s3c_hsudc_irq, 0,
                                driver_name, hsudc);
        if (ret < 0) {
                dev_err(dev, "irq request failed\n");
                goto err_res;
        }

        hsudc->uclk = devm_clk_get(&pdev->dev, "usb-device");
        if (IS_ERR(hsudc->uclk)) {
                dev_err(dev, "failed to find usb-device clock source\n");
                ret = PTR_ERR(hsudc->uclk);
                goto err_res;
        }
        clk_enable(hsudc->uclk);

        local_irq_disable();

        disable_irq(hsudc->irq);
        local_irq_enable();

        ret = usb_add_gadget_udc(&pdev->dev, &hsudc->gadget);
        if (ret)
                goto err_add_udc;

        pm_runtime_enable(dev);

        return 0;
err_add_udc:
        clk_disable(hsudc->uclk);
err_res:
        if (!IS_ERR_OR_NULL(hsudc->transceiver))
                usb_put_phy(hsudc->transceiver);

err_supplies:
        return ret;
}

static struct platform_driver s3c_hsudc_driver = {
        .driver         = {
                .name   = "s3c-hsudc",
        },
        .probe          = s3c_hsudc_probe,
};

module_platform_driver(s3c_hsudc_driver);

MODULE_DESCRIPTION("Samsung S3C24XX USB high-speed controller driver");
MODULE_AUTHOR("Thomas Abraham <thomas.ab@samsung.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:s3c-hsudc");