// SPDX-License-Identifier: GPL-2.0+
/*
 * USB Peripheral Controller driver for Aeroflex Gaisler GRUSBDC.
 *
 * 2013 (c) Aeroflex Gaisler AB
 *
 * This driver supports GRUSBDC USB Device Controller cores available in the
 * GRLIB VHDL IP core library.
 *
 * Full documentation of the GRUSBDC core can be found here:
 * http://www.gaisler.com/products/grlib/grip.pdf
 *
 * Contributors:
 * - Andreas Larsson <andreas@gaisler.com>
 * - Marko Isomaki
 */

/*
 * A GRUSBDC core can have up to 16 IN endpoints and 16 OUT endpoints each
 * individually configurable to any of the four USB transfer types. This driver
 * only supports cores in DMA mode.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/of_platform.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>

#include <asm/byteorder.h>

#include "gr_udc.h"

#define DRIVER_NAME     "gr_udc"
#define DRIVER_DESC     "Aeroflex Gaisler GRUSBDC USB Peripheral Controller"

static const char driver_name[] = DRIVER_NAME;
static const char driver_desc[] = DRIVER_DESC;

#define gr_read32(x) (ioread32be((x)))
#define gr_write32(x, v) (iowrite32be((v), (x)))

/* USB speed and corresponding string calculated from status register value */
#define GR_SPEED(status) \
        ((status & GR_STATUS_SP) ? USB_SPEED_FULL : USB_SPEED_HIGH)
#define GR_SPEED_STR(status) usb_speed_string(GR_SPEED(status))

/* Size of hardware buffer calculated from epctrl register value */
#define GR_BUFFER_SIZE(epctrl)                                        \
        ((((epctrl) & GR_EPCTRL_BUFSZ_MASK) >> GR_EPCTRL_BUFSZ_POS) * \
         GR_EPCTRL_BUFSZ_SCALER)

/* ---------------------------------------------------------------------- */
/* Debug printout functionality */

static const char * const gr_modestring[] = {"control", "iso", "bulk", "int"};

static const char *gr_ep0state_string(enum gr_ep0state state)
{
        static const char *const names[] = {
                [GR_EP0_DISCONNECT] = "disconnect",
                [GR_EP0_SETUP] = "setup",
                [GR_EP0_IDATA] = "idata",
                [GR_EP0_ODATA] = "odata",
                [GR_EP0_ISTATUS] = "istatus",
                [GR_EP0_OSTATUS] = "ostatus",
                [GR_EP0_STALL] = "stall",
                [GR_EP0_SUSPEND] = "suspend",
        };

        if (state < 0 || state >= ARRAY_SIZE(names))
                return "UNKNOWN";

        return names[state];
}

#ifdef VERBOSE_DEBUG

static void gr_dbgprint_request(const char *str, struct gr_ep *ep,
                                struct gr_request *req)
{
        int buflen = ep->is_in ? req->req.length : req->req.actual;
        int rowlen = 32;
        int plen = min(rowlen, buflen);

        dev_dbg(ep->dev->dev, "%s: 0x%p, %d bytes data%s:\n", str, req, buflen,
                (buflen > plen ? " (truncated)" : ""));
        print_hex_dump_debug("   ", DUMP_PREFIX_NONE,
                             rowlen, 4, req->req.buf, plen, false);
}

static void gr_dbgprint_devreq(struct gr_udc *dev, u8 type, u8 request,
                               u16 value, u16 index, u16 length)
{
        dev_vdbg(dev->dev, "REQ: %02x.%02x v%04x i%04x l%04x\n",
                 type, request, value, index, length);
}
#else /* !VERBOSE_DEBUG */

static void gr_dbgprint_request(const char *str, struct gr_ep *ep,
                                struct gr_request *req) {}

static void gr_dbgprint_devreq(struct gr_udc *dev, u8 type, u8 request,
                               u16 value, u16 index, u16 length) {}

#endif /* VERBOSE_DEBUG */

/* ---------------------------------------------------------------------- */
/* Debugfs functionality */

#ifdef CONFIG_USB_GADGET_DEBUG_FS

static void gr_seq_ep_show(struct seq_file *seq, struct gr_ep *ep)
{
        u32 epctrl = gr_read32(&ep->regs->epctrl);
        u32 epstat = gr_read32(&ep->regs->epstat);
        int mode = (epctrl & GR_EPCTRL_TT_MASK) >> GR_EPCTRL_TT_POS;
        struct gr_request *req;

        seq_printf(seq, "%s:\n", ep->ep.name);
        seq_printf(seq, "  mode = %s\n", gr_modestring[mode]);
        seq_printf(seq, "  halted: %d\n", !!(epctrl & GR_EPCTRL_EH));
        seq_printf(seq, "  disabled: %d\n", !!(epctrl & GR_EPCTRL_ED));
        seq_printf(seq, "  valid: %d\n", !!(epctrl & GR_EPCTRL_EV));
        seq_printf(seq, "  dma_start = %d\n", ep->dma_start);
        seq_printf(seq, "  stopped = %d\n", ep->stopped);
        seq_printf(seq, "  wedged = %d\n", ep->wedged);
        seq_printf(seq, "  callback = %d\n", ep->callback);
        seq_printf(seq, "  maxpacket = %d\n", ep->ep.maxpacket);
        seq_printf(seq, "  maxpacket_limit = %d\n", ep->ep.maxpacket_limit);
        seq_printf(seq, "  bytes_per_buffer = %d\n", ep->bytes_per_buffer);
        if (mode == 1 || mode == 3)
                seq_printf(seq, "  nt = %d\n",
                           (epctrl & GR_EPCTRL_NT_MASK) >> GR_EPCTRL_NT_POS);

        seq_printf(seq, "  Buffer 0: %s %s%d\n",
                   epstat & GR_EPSTAT_B0 ? "valid" : "invalid",
                   epstat & GR_EPSTAT_BS ? " " : "selected ",
                   (epstat & GR_EPSTAT_B0CNT_MASK) >> GR_EPSTAT_B0CNT_POS);
        seq_printf(seq, "  Buffer 1: %s %s%d\n",
                   epstat & GR_EPSTAT_B1 ? "valid" : "invalid",
                   epstat & GR_EPSTAT_BS ? "selected " : " ",
                   (epstat & GR_EPSTAT_B1CNT_MASK) >> GR_EPSTAT_B1CNT_POS);

        if (list_empty(&ep->queue)) {
                seq_puts(seq, "  Queue: empty\n\n");
                return;
        }

        seq_puts(seq, "  Queue:\n");
        list_for_each_entry(req, &ep->queue, queue) {
                struct gr_dma_desc *desc;
                struct gr_dma_desc *next;

                seq_printf(seq, "    0x%p: 0x%p %d %d\n", req,
                           &req->req.buf, req->req.actual, req->req.length);

                next = req->first_desc;
                do {
                        desc = next;
                        next = desc->next_desc;
                        seq_printf(seq, "    %c 0x%p (0x%08x): 0x%05x 0x%08x\n",
                                   desc == req->curr_desc ? 'c' : ' ',
                                   desc, desc->paddr, desc->ctrl, desc->data);
                } while (desc != req->last_desc);
        }
        seq_puts(seq, "\n");
}


static int gr_seq_show(struct seq_file *seq, void *v)
{
        struct gr_udc *dev = seq->private;
        u32 control = gr_read32(&dev->regs->control);
        u32 status = gr_read32(&dev->regs->status);
        struct gr_ep *ep;

        seq_printf(seq, "usb state = %s\n",
                   usb_state_string(dev->gadget.state));
        seq_printf(seq, "address = %d\n",
                   (control & GR_CONTROL_UA_MASK) >> GR_CONTROL_UA_POS);
        seq_printf(seq, "speed = %s\n", GR_SPEED_STR(status));
        seq_printf(seq, "ep0state = %s\n", gr_ep0state_string(dev->ep0state));
        seq_printf(seq, "irq_enabled = %d\n", dev->irq_enabled);
        seq_printf(seq, "remote_wakeup = %d\n", dev->remote_wakeup);
        seq_printf(seq, "test_mode = %d\n", dev->test_mode);
        seq_puts(seq, "\n");

        list_for_each_entry(ep, &dev->ep_list, ep_list)
                gr_seq_ep_show(seq, ep);

        return 0;
}

static int gr_dfs_open(struct inode *inode, struct file *file)
{
        return single_open(file, gr_seq_show, inode->i_private);
}

static const struct file_operations gr_dfs_fops = {
        .owner          = THIS_MODULE,
        .open           = gr_dfs_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void gr_dfs_create(struct gr_udc *dev)
{
        const char *name = "gr_udc_state";

        dev->dfs_root = debugfs_create_dir(dev_name(dev->dev), NULL);
        dev->dfs_state = debugfs_create_file(name, 0444, dev->dfs_root, dev,
                                             &gr_dfs_fops);
}

static void gr_dfs_delete(struct gr_udc *dev)
{
        /* Handles NULL and ERR pointers internally */
        debugfs_remove(dev->dfs_state);
        debugfs_remove(dev->dfs_root);
}

#else /* !CONFIG_USB_GADGET_DEBUG_FS */

static void gr_dfs_create(struct gr_udc *dev) {}
static void gr_dfs_delete(struct gr_udc *dev) {}

#endif /* CONFIG_USB_GADGET_DEBUG_FS */

/* ---------------------------------------------------------------------- */
/* DMA and request handling */

/* Allocates a new struct gr_dma_desc, sets paddr and zeroes the rest */
static struct gr_dma_desc *gr_alloc_dma_desc(struct gr_ep *ep, gfp_t gfp_flags)
{
        dma_addr_t paddr;
        struct gr_dma_desc *dma_desc;

        dma_desc = dma_pool_zalloc(ep->dev->desc_pool, gfp_flags, &paddr);
        if (!dma_desc) {
                dev_err(ep->dev->dev, "Could not allocate from DMA pool\n");
                return NULL;
        }

        dma_desc->paddr = paddr;

        return dma_desc;
}

static inline void gr_free_dma_desc(struct gr_udc *dev,
                                    struct gr_dma_desc *desc)
{
        dma_pool_free(dev->desc_pool, desc, (dma_addr_t)desc->paddr);
}

/* Frees the chain of struct gr_dma_desc for the given request */
static void gr_free_dma_desc_chain(struct gr_udc *dev, struct gr_request *req)
{
        struct gr_dma_desc *desc;
        struct gr_dma_desc *next;

        next = req->first_desc;
        if (!next)
                return;

        do {
                desc = next;
                next = desc->next_desc;
                gr_free_dma_desc(dev, desc);
        } while (desc != req->last_desc);

        req->first_desc = NULL;
        req->curr_desc = NULL;
        req->last_desc = NULL;
}

static void gr_ep0_setup(struct gr_udc *dev, struct gr_request *req);

/*
 * Frees allocated resources and calls the appropriate completion function/setup
 * package handler for a finished request.
 *
 * Must be called with dev->lock held and irqs disabled.
 */
static void gr_finish_request(struct gr_ep *ep, struct gr_request *req,
                              int status)
        __releases(&dev->lock)
        __acquires(&dev->lock)
{
        struct gr_udc *dev;

        list_del_init(&req->queue);

        if (likely(req->req.status == -EINPROGRESS))
                req->req.status = status;
        else
                status = req->req.status;

        dev = ep->dev;
        usb_gadget_unmap_request(&dev->gadget, &req->req, ep->is_in);
        gr_free_dma_desc_chain(dev, req);

        if (ep->is_in) { /* For OUT, req->req.actual gets updated bit by bit */
                req->req.actual = req->req.length;
        } else if (req->oddlen && req->req.actual > req->evenlen) {
                /*
                 * Copy to user buffer in this case where length was not evenly
                 * divisible by ep->ep.maxpacket and the last descriptor was
                 * actually used.
                 */
                char *buftail = ((char *)req->req.buf + req->evenlen);

                memcpy(buftail, ep->tailbuf, req->oddlen);

                if (req->req.actual > req->req.length) {
                        /* We got more data than was requested */
                        dev_dbg(ep->dev->dev, "Overflow for ep %s\n",
                                ep->ep.name);
                        gr_dbgprint_request("OVFL", ep, req);
                        req->req.status = -EOVERFLOW;
                }
        }

        if (!status) {
                if (ep->is_in)
                        gr_dbgprint_request("SENT", ep, req);
                else
                        gr_dbgprint_request("RECV", ep, req);
        }

        /* Prevent changes to ep->queue during callback */
        ep->callback = 1;
        if (req == dev->ep0reqo && !status) {
                if (req->setup)
                        gr_ep0_setup(dev, req);
                else
                        dev_err(dev->dev,
                                "Unexpected non setup packet on ep0in\n");
        } else if (req->req.complete) {
                spin_unlock(&dev->lock);

                usb_gadget_giveback_request(&ep->ep, &req->req);

                spin_lock(&dev->lock);
        }
        ep->callback = 0;
}

static struct usb_request *gr_alloc_request(struct usb_ep *_ep, gfp_t gfp_flags)
{
        struct gr_request *req;

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

        INIT_LIST_HEAD(&req->queue);

        return &req->req;
}

/*
 * Starts DMA for endpoint ep if there are requests in the queue.
 *
 * Must be called with dev->lock held and with !ep->stopped.
 */
static void gr_start_dma(struct gr_ep *ep)
{
        struct gr_request *req;
        u32 dmactrl;

        if (list_empty(&ep->queue)) {
                ep->dma_start = 0;
                return;
        }

        req = list_first_entry(&ep->queue, struct gr_request, queue);

        /* A descriptor should already have been allocated */
        BUG_ON(!req->curr_desc);

        /*
         * The DMA controller can not handle smaller OUT buffers than
         * ep->ep.maxpacket. It could lead to buffer overruns if an unexpectedly
         * long packet are received. Therefore an internal bounce buffer gets
         * used when such a request gets enabled.
         */
        if (!ep->is_in && req->oddlen)
                req->last_desc->data = ep->tailbuf_paddr;

        wmb(); /* Make sure all is settled before handing it over to DMA */

        /* Set the descriptor pointer in the hardware */
        gr_write32(&ep->regs->dmaaddr, req->curr_desc->paddr);

        /* Announce available descriptors */
        dmactrl = gr_read32(&ep->regs->dmactrl);
        gr_write32(&ep->regs->dmactrl, dmactrl | GR_DMACTRL_DA);

        ep->dma_start = 1;
}

/*
 * Finishes the first request in the ep's queue and, if available, starts the
 * next request in queue.
 *
 * Must be called with dev->lock held, irqs disabled and with !ep->stopped.
 */
static void gr_dma_advance(struct gr_ep *ep, int status)
{
        struct gr_request *req;

        req = list_first_entry(&ep->queue, struct gr_request, queue);
        gr_finish_request(ep, req, status);
        gr_start_dma(ep); /* Regardless of ep->dma_start */
}

/*
 * Abort DMA for an endpoint. Sets the abort DMA bit which causes an ongoing DMA
 * transfer to be canceled and clears GR_DMACTRL_DA.
 *
 * Must be called with dev->lock held.
 */
static void gr_abort_dma(struct gr_ep *ep)
{
        u32 dmactrl;

        dmactrl = gr_read32(&ep->regs->dmactrl);
        gr_write32(&ep->regs->dmactrl, dmactrl | GR_DMACTRL_AD);
}

/*
 * Allocates and sets up a struct gr_dma_desc and putting it on the descriptor
 * chain.
 *
 * Size is not used for OUT endpoints. Hardware can not be instructed to handle
 * smaller buffer than MAXPL in the OUT direction.
 */
static int gr_add_dma_desc(struct gr_ep *ep, struct gr_request *req,
                           dma_addr_t data, unsigned size, gfp_t gfp_flags)
{
        struct gr_dma_desc *desc;

        desc = gr_alloc_dma_desc(ep, gfp_flags);
        if (!desc)
                return -ENOMEM;

        desc->data = data;
        if (ep->is_in)
                desc->ctrl =
                        (GR_DESC_IN_CTRL_LEN_MASK & size) | GR_DESC_IN_CTRL_EN;
        else
                desc->ctrl = GR_DESC_OUT_CTRL_IE;

        if (!req->first_desc) {
                req->first_desc = desc;
                req->curr_desc = desc;
        } else {
                req->last_desc->next_desc = desc;
                req->last_desc->next = desc->paddr;
                req->last_desc->ctrl |= GR_DESC_OUT_CTRL_NX;
        }
        req->last_desc = desc;

        return 0;
}

/*
 * Sets up a chain of struct gr_dma_descriptors pointing to buffers that
 * together covers req->req.length bytes of the buffer at DMA address
 * req->req.dma for the OUT direction.
 *
 * The first descriptor in the chain is enabled, the rest disabled. The
 * interrupt handler will later enable them one by one when needed so we can
 * find out when the transfer is finished. For OUT endpoints, all descriptors
 * therefore generate interrutps.
 */
static int gr_setup_out_desc_list(struct gr_ep *ep, struct gr_request *req,
                                  gfp_t gfp_flags)
{
        u16 bytes_left; /* Bytes left to provide descriptors for */
        u16 bytes_used; /* Bytes accommodated for */
        int ret = 0;

        req->first_desc = NULL; /* Signals that no allocation is done yet */
        bytes_left = req->req.length;
        bytes_used = 0;
        while (bytes_left > 0) {
                dma_addr_t start = req->req.dma + bytes_used;
                u16 size = min(bytes_left, ep->bytes_per_buffer);

                if (size < ep->bytes_per_buffer) {
                        /* Prepare using bounce buffer */
                        req->evenlen = req->req.length - bytes_left;
                        req->oddlen = size;
                }

                ret = gr_add_dma_desc(ep, req, start, size, gfp_flags);
                if (ret)
                        goto alloc_err;

                bytes_left -= size;
                bytes_used += size;
        }

        req->first_desc->ctrl |= GR_DESC_OUT_CTRL_EN;

        return 0;

alloc_err:
        gr_free_dma_desc_chain(ep->dev, req);

        return ret;
}

/*
 * Sets up a chain of struct gr_dma_descriptors pointing to buffers that
 * together covers req->req.length bytes of the buffer at DMA address
 * req->req.dma for the IN direction.
 *
 * When more data is provided than the maximum payload size, the hardware splits
 * this up into several payloads automatically. Moreover, ep->bytes_per_buffer
 * is always set to a multiple of the maximum payload (restricted to the valid
 * number of maximum payloads during high bandwidth isochronous or interrupt
 * transfers)
 *
 * All descriptors are enabled from the beginning and we only generate an
 * interrupt for the last one indicating that the entire request has been pushed
 * to hardware.
 */
static int gr_setup_in_desc_list(struct gr_ep *ep, struct gr_request *req,
                                 gfp_t gfp_flags)
{
        u16 bytes_left; /* Bytes left in req to provide descriptors for */
        u16 bytes_used; /* Bytes in req accommodated for */
        int ret = 0;

        req->first_desc = NULL; /* Signals that no allocation is done yet */
        bytes_left = req->req.length;
        bytes_used = 0;
        do { /* Allow for zero length packets */
                dma_addr_t start = req->req.dma + bytes_used;
                u16 size = min(bytes_left, ep->bytes_per_buffer);

                ret = gr_add_dma_desc(ep, req, start, size, gfp_flags);
                if (ret)
                        goto alloc_err;

                bytes_left -= size;
                bytes_used += size;
        } while (bytes_left > 0);

        /*
         * Send an extra zero length packet to indicate that no more data is
         * available when req->req.zero is set and the data length is even
         * multiples of ep->ep.maxpacket.
         */
        if (req->req.zero && (req->req.length % ep->ep.maxpacket == 0)) {
                ret = gr_add_dma_desc(ep, req, 0, 0, gfp_flags);
                if (ret)
                        goto alloc_err;
        }

        /*
         * For IN packets we only want to know when the last packet has been
         * transmitted (not just put into internal buffers).
         */
        req->last_desc->ctrl |= GR_DESC_IN_CTRL_PI;

        return 0;

alloc_err:
        gr_free_dma_desc_chain(ep->dev, req);

        return ret;
}

/* Must be called with dev->lock held */
static int gr_queue(struct gr_ep *ep, struct gr_request *req, gfp_t gfp_flags)
{
        struct gr_udc *dev = ep->dev;
        int ret;

        if (unlikely(!ep->ep.desc && ep->num != 0)) {
                dev_err(dev->dev, "No ep descriptor for %s\n", ep->ep.name);
                return -EINVAL;
        }

        if (unlikely(!req->req.buf || !list_empty(&req->queue))) {
                dev_err(dev->dev,
                        "Invalid request for %s: buf=%p list_empty=%d\n",
                        ep->ep.name, req->req.buf, list_empty(&req->queue));
                return -EINVAL;
        }

        if (unlikely(!dev->driver || dev->gadget.speed == USB_SPEED_UNKNOWN)) {
                dev_err(dev->dev, "-ESHUTDOWN");
                return -ESHUTDOWN;
        }

        /* Can't touch registers when suspended */
        if (dev->ep0state == GR_EP0_SUSPEND) {
                dev_err(dev->dev, "-EBUSY");
                return -EBUSY;
        }

        /* Set up DMA mapping in case the caller didn't */
        ret = usb_gadget_map_request(&dev->gadget, &req->req, ep->is_in);
        if (ret) {
                dev_err(dev->dev, "usb_gadget_map_request");
                return ret;
        }

        if (ep->is_in)
                ret = gr_setup_in_desc_list(ep, req, gfp_flags);
        else
                ret = gr_setup_out_desc_list(ep, req, gfp_flags);
        if (ret)
                return ret;

        req->req.status = -EINPROGRESS;
        req->req.actual = 0;
        list_add_tail(&req->queue, &ep->queue);

        /* Start DMA if not started, otherwise interrupt handler handles it */
        if (!ep->dma_start && likely(!ep->stopped))
                gr_start_dma(ep);

        return 0;
}

/*
 * Queue a request from within the driver.
 *
 * Must be called with dev->lock held.
 */
static inline int gr_queue_int(struct gr_ep *ep, struct gr_request *req,
                               gfp_t gfp_flags)
{
        if (ep->is_in)
                gr_dbgprint_request("RESP", ep, req);

        return gr_queue(ep, req, gfp_flags);
}

/* ---------------------------------------------------------------------- */
/* General helper functions */

/*
 * Dequeue ALL requests.
 *
 * Must be called with dev->lock held and irqs disabled.
 */
static void gr_ep_nuke(struct gr_ep *ep)
{
        struct gr_request *req;

        ep->stopped = 1;
        ep->dma_start = 0;
        gr_abort_dma(ep);

        while (!list_empty(&ep->queue)) {
                req = list_first_entry(&ep->queue, struct gr_request, queue);
                gr_finish_request(ep, req, -ESHUTDOWN);
        }
}

/*
 * Reset the hardware state of this endpoint.
 *
 * Must be called with dev->lock held.
 */
static void gr_ep_reset(struct gr_ep *ep)
{
        gr_write32(&ep->regs->epctrl, 0);
        gr_write32(&ep->regs->dmactrl, 0);

        ep->ep.maxpacket = MAX_CTRL_PL_SIZE;
        ep->ep.desc = NULL;
        ep->stopped = 1;
        ep->dma_start = 0;
}

/*
 * Generate STALL on ep0in/out.
 *
 * Must be called with dev->lock held.
 */
static void gr_control_stall(struct gr_udc *dev)
{
        u32 epctrl;

        epctrl = gr_read32(&dev->epo[0].regs->epctrl);
        gr_write32(&dev->epo[0].regs->epctrl, epctrl | GR_EPCTRL_CS);
        epctrl = gr_read32(&dev->epi[0].regs->epctrl);
        gr_write32(&dev->epi[0].regs->epctrl, epctrl | GR_EPCTRL_CS);

        dev->ep0state = GR_EP0_STALL;
}

/*
 * Halts, halts and wedges, or clears halt for an endpoint.
 *
 * Must be called with dev->lock held.
 */
static int gr_ep_halt_wedge(struct gr_ep *ep, int halt, int wedge, int fromhost)
{
        u32 epctrl;
        int retval = 0;

        if (ep->num && !ep->ep.desc)
                return -EINVAL;

        if (ep->num && ep->ep.desc->bmAttributes == USB_ENDPOINT_XFER_ISOC)
                return -EOPNOTSUPP;

        /* Never actually halt ep0, and therefore never clear halt for ep0 */
        if (!ep->num) {
                if (halt && !fromhost) {
                        /* ep0 halt from gadget - generate protocol stall */
                        gr_control_stall(ep->dev);
                        dev_dbg(ep->dev->dev, "EP: stall ep0\n");
                        return 0;
                }
                return -EINVAL;
        }

        dev_dbg(ep->dev->dev, "EP: %s halt %s\n",
                (halt ? (wedge ? "wedge" : "set") : "clear"), ep->ep.name);

        epctrl = gr_read32(&ep->regs->epctrl);
        if (halt) {
                /* Set HALT */
                gr_write32(&ep->regs->epctrl, epctrl | GR_EPCTRL_EH);
                ep->stopped = 1;
                if (wedge)
                        ep->wedged = 1;
        } else {
                gr_write32(&ep->regs->epctrl, epctrl & ~GR_EPCTRL_EH);
                ep->stopped = 0;
                ep->wedged = 0;

                /* Things might have been queued up in the meantime */
                if (!ep->dma_start)
                        gr_start_dma(ep);
        }

        return retval;
}

/* Must be called with dev->lock held */
static inline void gr_set_ep0state(struct gr_udc *dev, enum gr_ep0state value)
{
        if (dev->ep0state != value)
                dev_vdbg(dev->dev, "STATE:  ep0state=%s\n",
                         gr_ep0state_string(value));
        dev->ep0state = value;
}

/*
 * Should only be called when endpoints can not generate interrupts.
 *
 * Must be called with dev->lock held.
 */
static void gr_disable_interrupts_and_pullup(struct gr_udc *dev)
{
        gr_write32(&dev->regs->control, 0);
        wmb(); /* Make sure that we do not deny one of our interrupts */
        dev->irq_enabled = 0;
}

/*
 * Stop all device activity and disable data line pullup.
 *
 * Must be called with dev->lock held and irqs disabled.
 */
static void gr_stop_activity(struct gr_udc *dev)
{
        struct gr_ep *ep;

        list_for_each_entry(ep, &dev->ep_list, ep_list)
                gr_ep_nuke(ep);

        gr_disable_interrupts_and_pullup(dev);

        gr_set_ep0state(dev, GR_EP0_DISCONNECT);
        usb_gadget_set_state(&dev->gadget, USB_STATE_NOTATTACHED);
}

/* ---------------------------------------------------------------------- */
/* ep0 setup packet handling */

static void gr_ep0_testmode_complete(struct usb_ep *_ep,
                                     struct usb_request *_req)
{
        struct gr_ep *ep;
        struct gr_udc *dev;
        u32 control;

        ep = container_of(_ep, struct gr_ep, ep);
        dev = ep->dev;

        spin_lock(&dev->lock);

        control = gr_read32(&dev->regs->control);
        control |= GR_CONTROL_TM | (dev->test_mode << GR_CONTROL_TS_POS);
        gr_write32(&dev->regs->control, control);

        spin_unlock(&dev->lock);
}

static void gr_ep0_dummy_complete(struct usb_ep *_ep, struct usb_request *_req)
{
        /* Nothing needs to be done here */
}

/*
 * Queue a response on ep0in.
 *
 * Must be called with dev->lock held.
 */
static int gr_ep0_respond(struct gr_udc *dev, u8 *buf, int length,
                          void (*complete)(struct usb_ep *ep,
                                           struct usb_request *req))
{
        u8 *reqbuf = dev->ep0reqi->req.buf;
        int status;
        int i;

        for (i = 0; i < length; i++)
                reqbuf[i] = buf[i];
        dev->ep0reqi->req.length = length;
        dev->ep0reqi->req.complete = complete;

        status = gr_queue_int(&dev->epi[0], dev->ep0reqi, GFP_ATOMIC);
        if (status < 0)
                dev_err(dev->dev,
                        "Could not queue ep0in setup response: %d\n", status);

        return status;
}

/*
 * Queue a 2 byte response on ep0in.
 *
 * Must be called with dev->lock held.
 */
static inline int gr_ep0_respond_u16(struct gr_udc *dev, u16 response)
{
        __le16 le_response = cpu_to_le16(response);

        return gr_ep0_respond(dev, (u8 *)&le_response, 2,
                              gr_ep0_dummy_complete);
}

/*
 * Queue a ZLP response on ep0in.
 *
 * Must be called with dev->lock held.
 */
static inline int gr_ep0_respond_empty(struct gr_udc *dev)
{
        return gr_ep0_respond(dev, NULL, 0, gr_ep0_dummy_complete);
}

/*
 * This is run when a SET_ADDRESS request is received. First writes
 * the new address to the control register which is updated internally
 * when the next IN packet is ACKED.
 *
 * Must be called with dev->lock held.
 */
static void gr_set_address(struct gr_udc *dev, u8 address)
{
        u32 control;

        control = gr_read32(&dev->regs->control) & ~GR_CONTROL_UA_MASK;
        control |= (address << GR_CONTROL_UA_POS) & GR_CONTROL_UA_MASK;
        control |= GR_CONTROL_SU;
        gr_write32(&dev->regs->control, control);
}

/*
 * Returns negative for STALL, 0 for successful handling and positive for
 * delegation.
 *
 * Must be called with dev->lock held.
 */
static int gr_device_request(struct gr_udc *dev, u8 type, u8 request,
                             u16 value, u16 index)
{
        u16 response;
        u8 test;

        switch (request) {
        case USB_REQ_SET_ADDRESS:
                dev_dbg(dev->dev, "STATUS: address %d\n", value & 0xff);
                gr_set_address(dev, value & 0xff);
                if (value)
                        usb_gadget_set_state(&dev->gadget, USB_STATE_ADDRESS);
                else
                        usb_gadget_set_state(&dev->gadget, USB_STATE_DEFAULT);
                return gr_ep0_respond_empty(dev);

        case USB_REQ_GET_STATUS:
                /* Self powered | remote wakeup */
                response = 0x0001 | (dev->remote_wakeup ? 0x0002 : 0);
                return gr_ep0_respond_u16(dev, response);

        case USB_REQ_SET_FEATURE:
                switch (value) {
                case USB_DEVICE_REMOTE_WAKEUP:
                        /* Allow remote wakeup */
                        dev->remote_wakeup = 1;
                        return gr_ep0_respond_empty(dev);

                case USB_DEVICE_TEST_MODE:
                        /* The hardware does not support TEST_FORCE_EN */
                        test = index >> 8;
                        if (test >= TEST_J && test <= TEST_PACKET) {
                                dev->test_mode = test;
                                return gr_ep0_respond(dev, NULL, 0,
                                                      gr_ep0_testmode_complete);
                        }
                }
                break;

        case USB_REQ_CLEAR_FEATURE:
                switch (value) {
                case USB_DEVICE_REMOTE_WAKEUP:
                        /* Disallow remote wakeup */
                        dev->remote_wakeup = 0;
                        return gr_ep0_respond_empty(dev);
                }
                break;
        }

        return 1; /* Delegate the rest */
}

/*
 * Returns negative for STALL, 0 for successful handling and positive for
 * delegation.
 *
 * Must be called with dev->lock held.
 */
static int gr_interface_request(struct gr_udc *dev, u8 type, u8 request,
                                u16 value, u16 index)
{
        if (dev->gadget.state != USB_STATE_CONFIGURED)
                return -1;

        /*
         * Should return STALL for invalid interfaces, but udc driver does not
         * know anything about that. However, many gadget drivers do not handle
         * GET_STATUS so we need to take care of that.
         */

        switch (request) {
        case USB_REQ_GET_STATUS:
                return gr_ep0_respond_u16(dev, 0x0000);

        case USB_REQ_SET_FEATURE:
        case USB_REQ_CLEAR_FEATURE:
                /*
                 * No possible valid standard requests. Still let gadget drivers
                 * have a go at it.
                 */
                break;
        }

        return 1; /* Delegate the rest */
}

/*
 * Returns negative for STALL, 0 for successful handling and positive for
 * delegation.
 *
 * Must be called with dev->lock held.
 */
static int gr_endpoint_request(struct gr_udc *dev, u8 type, u8 request,
                               u16 value, u16 index)
{
        struct gr_ep *ep;
        int status;
        int halted;
        u8 epnum = index & USB_ENDPOINT_NUMBER_MASK;

        u8 is_in = index & USB_ENDPOINT_DIR_MASK;

        if ((is_in && epnum >= dev->nepi) || (!is_in && epnum >= dev->nepo))
                return -1;

        if (dev->gadget.state != USB_STATE_CONFIGURED && epnum != 0)
                return -1;

        ep = (is_in ? &dev->epi[epnum] : &dev->epo[epnum]);

        switch (request) {
        case USB_REQ_GET_STATUS:
                halted = gr_read32(&ep->regs->epctrl) & GR_EPCTRL_EH;
                return gr_ep0_respond_u16(dev, halted ? 0x0001 : 0);

        case USB_REQ_SET_FEATURE:
                switch (value) {
                case USB_ENDPOINT_HALT:
                        status = gr_ep_halt_wedge(ep, 1, 0, 1);
                        if (status >= 0)
                                status = gr_ep0_respond_empty(dev);
                        return status;
                }
                break;

        case USB_REQ_CLEAR_FEATURE:
                switch (value) {
                case USB_ENDPOINT_HALT:
                        if (ep->wedged)
                                return -1;
                        status = gr_ep_halt_wedge(ep, 0, 0, 1);
                        if (status >= 0)
                                status = gr_ep0_respond_empty(dev);
                        return status;
                }
                break;
        }

        return 1; /* Delegate the rest */
}

/* Must be called with dev->lock held */
static void gr_ep0out_requeue(struct gr_udc *dev)
{
        int ret = gr_queue_int(&dev->epo[0], dev->ep0reqo, GFP_ATOMIC);

        if (ret)
                dev_err(dev->dev, "Could not queue ep0out setup request: %d\n",
                        ret);
}

/*
 * The main function dealing with setup requests on ep0.
 *
 * Must be called with dev->lock held and irqs disabled
 */
static void gr_ep0_setup(struct gr_udc *dev, struct gr_request *req)
        __releases(&dev->lock)
        __acquires(&dev->lock)
{
        union {
                struct usb_ctrlrequest ctrl;
                u8 raw[8];
                u32 word[2];
        } u;
        u8 type;
        u8 request;
        u16 value;
        u16 index;
        u16 length;
        int i;
        int status;

        /* Restore from ep0 halt */
        if (dev->ep0state == GR_EP0_STALL) {
                gr_set_ep0state(dev, GR_EP0_SETUP);
                if (!req->req.actual)
                        goto out;
        }

        if (dev->ep0state == GR_EP0_ISTATUS) {
                gr_set_ep0state(dev, GR_EP0_SETUP);
                if (req->req.actual > 0)
                        dev_dbg(dev->dev,
                                "Unexpected setup packet at state %s\n",
                                gr_ep0state_string(GR_EP0_ISTATUS));
                else
                        goto out; /* Got expected ZLP */
        } else if (dev->ep0state != GR_EP0_SETUP) {
                dev_info(dev->dev,
                         "Unexpected ep0out request at state %s - stalling\n",
                         gr_ep0state_string(dev->ep0state));
                gr_control_stall(dev);
                gr_set_ep0state(dev, GR_EP0_SETUP);
                goto out;
        } else if (!req->req.actual) {
                dev_dbg(dev->dev, "Unexpected ZLP at state %s\n",
                        gr_ep0state_string(dev->ep0state));
                goto out;
        }

        /* Handle SETUP packet */
        for (i = 0; i < req->req.actual; i++)
                u.raw[i] = ((u8 *)req->req.buf)[i];

        type = u.ctrl.bRequestType;
        request = u.ctrl.bRequest;
        value = le16_to_cpu(u.ctrl.wValue);
        index = le16_to_cpu(u.ctrl.wIndex);
        length = le16_to_cpu(u.ctrl.wLength);

        gr_dbgprint_devreq(dev, type, request, value, index, length);

        /* Check for data stage */
        if (length) {
                if (type & USB_DIR_IN)
                        gr_set_ep0state(dev, GR_EP0_IDATA);
                else
                        gr_set_ep0state(dev, GR_EP0_ODATA);
        }

        status = 1; /* Positive status flags delegation */
        if ((type & USB_TYPE_MASK) == USB_TYPE_STANDARD) {
                switch (type & USB_RECIP_MASK) {
                case USB_RECIP_DEVICE:
                        status = gr_device_request(dev, type, request,
                                                   value, index);
                        break;
                case USB_RECIP_ENDPOINT:
                        status =  gr_endpoint_request(dev, type, request,
                                                      value, index);
                        break;
                case USB_RECIP_INTERFACE:
                        status = gr_interface_request(dev, type, request,
                                                      value, index);
                        break;
                }
        }

        if (status > 0) {
                spin_unlock(&dev->lock);

                dev_vdbg(dev->dev, "DELEGATE\n");
                status = dev->driver->setup(&dev->gadget, &u.ctrl);

                spin_lock(&dev->lock);
        }

        /* Generate STALL on both ep0out and ep0in if requested */
        if (unlikely(status < 0)) {
                dev_vdbg(dev->dev, "STALL\n");
                gr_control_stall(dev);
        }

        if ((type & USB_TYPE_MASK) == USB_TYPE_STANDARD &&
            request == USB_REQ_SET_CONFIGURATION) {
                if (!value) {
                        dev_dbg(dev->dev, "STATUS: deconfigured\n");
                        usb_gadget_set_state(&dev->gadget, USB_STATE_ADDRESS);
                } else if (status >= 0) {
                        /* Not configured unless gadget OK:s it */
                        dev_dbg(dev->dev, "STATUS: configured: %d\n", value);
                        usb_gadget_set_state(&dev->gadget,
                                             USB_STATE_CONFIGURED);
                }
        }

        /* Get ready for next stage */
        if (dev->ep0state == GR_EP0_ODATA)
                gr_set_ep0state(dev, GR_EP0_OSTATUS);
        else if (dev->ep0state == GR_EP0_IDATA)
                gr_set_ep0state(dev, GR_EP0_ISTATUS);
        else
                gr_set_ep0state(dev, GR_EP0_SETUP);

out:
        gr_ep0out_requeue(dev);
}

/* ---------------------------------------------------------------------- */
/* VBUS and USB reset handling */

/* Must be called with dev->lock held and irqs disabled  */
static void gr_vbus_connected(struct gr_udc *dev, u32 status)
{
        u32 control;

        dev->gadget.speed = GR_SPEED(status);
        usb_gadget_set_state(&dev->gadget, USB_STATE_POWERED);

        /* Turn on full interrupts and pullup */
        control = (GR_CONTROL_SI | GR_CONTROL_UI | GR_CONTROL_VI |
                   GR_CONTROL_SP | GR_CONTROL_EP);
        gr_write32(&dev->regs->control, control);
}

/* Must be called with dev->lock held */
static void gr_enable_vbus_detect(struct gr_udc *dev)
{
        u32 status;

        dev->irq_enabled = 1;
        wmb(); /* Make sure we do not ignore an interrupt */
        gr_write32(&dev->regs->control, GR_CONTROL_VI);

        /* Take care of the case we are already plugged in at this point */
        status = gr_read32(&dev->regs->status);
        if (status & GR_STATUS_VB)
                gr_vbus_connected(dev, status);
}

/* Must be called with dev->lock held and irqs disabled */
static void gr_vbus_disconnected(struct gr_udc *dev)
{
        gr_stop_activity(dev);

        /* Report disconnect */
        if (dev->driver && dev->driver->disconnect) {
                spin_unlock(&dev->lock);

                dev->driver->disconnect(&dev->gadget);

                spin_lock(&dev->lock);
        }

        gr_enable_vbus_detect(dev);
}

/* Must be called with dev->lock held and irqs disabled */
static void gr_udc_usbreset(struct gr_udc *dev, u32 status)
{
        gr_set_address(dev, 0);
        gr_set_ep0state(dev, GR_EP0_SETUP);
        usb_gadget_set_state(&dev->gadget, USB_STATE_DEFAULT);
        dev->gadget.speed = GR_SPEED(status);

        gr_ep_nuke(&dev->epo[0]);
        gr_ep_nuke(&dev->epi[0]);
        dev->epo[0].stopped = 0;
        dev->epi[0].stopped = 0;
        gr_ep0out_requeue(dev);
}

/* ---------------------------------------------------------------------- */
/* Irq handling */

/*
 * Handles interrupts from in endpoints. Returns whether something was handled.
 *
 * Must be called with dev->lock held, irqs disabled and with !ep->stopped.
 */
static int gr_handle_in_ep(struct gr_ep *ep)
{
        struct gr_request *req;

        req = list_first_entry(&ep->queue, struct gr_request, queue);
        if (!req->last_desc)
                return 0;

        if (READ_ONCE(req->last_desc->ctrl) & GR_DESC_IN_CTRL_EN)
                return 0; /* Not put in hardware buffers yet */

        if (gr_read32(&ep->regs->epstat) & (GR_EPSTAT_B1 | GR_EPSTAT_B0))
                return 0; /* Not transmitted yet, still in hardware buffers */

        /* Write complete */
        gr_dma_advance(ep, 0);

        return 1;
}

/*
 * Handles interrupts from out endpoints. Returns whether something was handled.
 *
 * Must be called with dev->lock held, irqs disabled and with !ep->stopped.
 */
static int gr_handle_out_ep(struct gr_ep *ep)
{
        u32 ep_dmactrl;
        u32 ctrl;
        u16 len;
        struct gr_request *req;
        struct gr_udc *dev = ep->dev;

        req = list_first_entry(&ep->queue, struct gr_request, queue);
        if (!req->curr_desc)
                return 0;

        ctrl = READ_ONCE(req->curr_desc->ctrl);
        if (ctrl & GR_DESC_OUT_CTRL_EN)
                return 0; /* Not received yet */

        /* Read complete */
        len = ctrl & GR_DESC_OUT_CTRL_LEN_MASK;
        req->req.actual += len;
        if (ctrl & GR_DESC_OUT_CTRL_SE)
                req->setup = 1;

        if (len < ep->ep.maxpacket || req->req.actual >= req->req.length) {
                /* Short packet or >= expected size - we are done */

                if ((ep == &dev->epo[0]) && (dev->ep0state == GR_EP0_OSTATUS)) {
                        /*
                         * Send a status stage ZLP to ack the DATA stage in the
                         * OUT direction. This needs to be done before
                         * gr_dma_advance as that can lead to a call to
                         * ep0_setup that can change dev->ep0state.
                         */
                        gr_ep0_respond_empty(dev);
                        gr_set_ep0state(dev, GR_EP0_SETUP);
                }

                gr_dma_advance(ep, 0);
        } else {
                /* Not done yet. Enable the next descriptor to receive more. */
                req->curr_desc = req->curr_desc->next_desc;
                req->curr_desc->ctrl |= GR_DESC_OUT_CTRL_EN;

                ep_dmactrl = gr_read32(&ep->regs->dmactrl);
                gr_write32(&ep->regs->dmactrl, ep_dmactrl | GR_DMACTRL_DA);
        }

        return 1;
}

/*
 * Handle state changes. Returns whether something was handled.
 *
 * Must be called with dev->lock held and irqs disabled.
 */
static int gr_handle_state_changes(struct gr_udc *dev)
{
        u32 status = gr_read32(&dev->regs->status);
        int handled = 0;
        int powstate = !(dev->gadget.state == USB_STATE_NOTATTACHED ||
                         dev->gadget.state == USB_STATE_ATTACHED);

        /* VBUS valid detected */
        if (!powstate && (status & GR_STATUS_VB)) {
                dev_dbg(dev->dev, "STATUS: vbus valid detected\n");
                gr_vbus_connected(dev, status);
                handled = 1;
        }

        /* Disconnect */
        if (powstate && !(status & GR_STATUS_VB)) {
                dev_dbg(dev->dev, "STATUS: vbus invalid detected\n");
                gr_vbus_disconnected(dev);
                handled = 1;
        }

        /* USB reset detected */
        if (status & GR_STATUS_UR) {
                dev_dbg(dev->dev, "STATUS: USB reset - speed is %s\n",
                        GR_SPEED_STR(status));
                gr_write32(&dev->regs->status, GR_STATUS_UR);
                gr_udc_usbreset(dev, status);
                handled = 1;
        }

        /* Speed change */
        if (dev->gadget.speed != GR_SPEED(status)) {
                dev_dbg(dev->dev, "STATUS: USB Speed change to %s\n",
                        GR_SPEED_STR(status));
                dev->gadget.speed = GR_SPEED(status);
                handled = 1;
        }

        /* Going into suspend */
        if ((dev->ep0state != GR_EP0_SUSPEND) && !(status & GR_STATUS_SU)) {
                dev_dbg(dev->dev, "STATUS: USB suspend\n");
                gr_set_ep0state(dev, GR_EP0_SUSPEND);
                dev->suspended_from = dev->gadget.state;
                usb_gadget_set_state(&dev->gadget, USB_STATE_SUSPENDED);

                if ((dev->gadget.speed != USB_SPEED_UNKNOWN) &&
                    dev->driver && dev->driver->suspend) {
                        spin_unlock(&dev->lock);

                        dev->driver->suspend(&dev->gadget);

                        spin_lock(&dev->lock);
                }
                handled = 1;
        }

        /* Coming out of suspend */
        if ((dev->ep0state == GR_EP0_SUSPEND) && (status & GR_STATUS_SU)) {
                dev_dbg(dev->dev, "STATUS: USB resume\n");
                if (dev->suspended_from == USB_STATE_POWERED)
                        gr_set_ep0state(dev, GR_EP0_DISCONNECT);
                else
                        gr_set_ep0state(dev, GR_EP0_SETUP);
                usb_gadget_set_state(&dev->gadget, dev->suspended_from);

                if ((dev->gadget.speed != USB_SPEED_UNKNOWN) &&
                    dev->driver && dev->driver->resume) {
                        spin_unlock(&dev->lock);

                        dev->driver->resume(&dev->gadget);

                        spin_lock(&dev->lock);
                }
                handled = 1;
        }

        return handled;
}

/* Non-interrupt context irq handler */
static irqreturn_t gr_irq_handler(int irq, void *_dev)
{
        struct gr_udc *dev = _dev;
        struct gr_ep *ep;
        int handled = 0;
        int i;
        unsigned long flags;

        spin_lock_irqsave(&dev->lock, flags);

        if (!dev->irq_enabled)
                goto out;

        /*
         * Check IN ep interrupts. We check these before the OUT eps because
         * some gadgets reuse the request that might already be currently
         * outstanding and needs to be completed (mainly setup requests).
         */
        for (i = 0; i < dev->nepi; i++) {
                ep = &dev->epi[i];
                if (!ep->stopped && !ep->callback && !list_empty(&ep->queue))
                        handled = gr_handle_in_ep(ep) || handled;
        }

        /* Check OUT ep interrupts */
        for (i = 0; i < dev->nepo; i++) {
                ep = &dev->epo[i];
                if (!ep->stopped && !ep->callback && !list_empty(&ep->queue))
                        handled = gr_handle_out_ep(ep) || handled;
        }

        /* Check status interrupts */
        handled = gr_handle_state_changes(dev) || handled;

        /*
         * Check AMBA DMA errors. Only check if we didn't find anything else to
         * handle because this shouldn't happen if we did everything right.
         */
        if (!handled) {
                list_for_each_entry(ep, &dev->ep_list, ep_list) {
                        if (gr_read32(&ep->regs->dmactrl) & GR_DMACTRL_AE) {
                                dev_err(dev->dev,
                                        "AMBA Error occurred for %s\n",
                                        ep->ep.name);
                                handled = 1;
                        }
                }
        }

out:
        spin_unlock_irqrestore(&dev->lock, flags);

        return handled ? IRQ_HANDLED : IRQ_NONE;
}

/* Interrupt context irq handler */
static irqreturn_t gr_irq(int irq, void *_dev)
{
        struct gr_udc *dev = _dev;

        if (!dev->irq_enabled)
                return IRQ_NONE;

        return IRQ_WAKE_THREAD;
}

/* ---------------------------------------------------------------------- */
/* USB ep ops */

/* Enable endpoint. Not for ep0in and ep0out that are handled separately. */
static int gr_ep_enable(struct usb_ep *_ep,
                        const struct usb_endpoint_descriptor *desc)
{
        struct gr_udc *dev;
        struct gr_ep *ep;
        u8 mode;
        u8 nt;
        u16 max;
        u16 buffer_size = 0;
        u32 epctrl;

        ep = container_of(_ep, struct gr_ep, ep);
        if (!_ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT)
                return -EINVAL;

        dev = ep->dev;

        /* 'ep0' IN and OUT are reserved */
        if (ep == &dev->epo[0] || ep == &dev->epi[0])
                return -EINVAL;

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

        /* Make sure we are clear for enabling */
        epctrl = gr_read32(&ep->regs->epctrl);
        if (epctrl & GR_EPCTRL_EV)
                return -EBUSY;

        /* Check that directions match */
        if (!ep->is_in != !usb_endpoint_dir_in(desc))
                return -EINVAL;

        /* Check ep num */
        if ((!ep->is_in && ep->num >= dev->nepo) ||
            (ep->is_in && ep->num >= dev->nepi))
                return -EINVAL;

        if (usb_endpoint_xfer_control(desc)) {
                mode = 0;
        } else if (usb_endpoint_xfer_isoc(desc)) {
                mode = 1;
        } else if (usb_endpoint_xfer_bulk(desc)) {
                mode = 2;
        } else if (usb_endpoint_xfer_int(desc)) {
                mode = 3;
        } else {
                dev_err(dev->dev, "Unknown transfer type for %s\n",
                        ep->ep.name);
                return -EINVAL;
        }

        /*
         * Bits 10-0 set the max payload. 12-11 set the number of
         * additional transactions.
         */
        max = usb_endpoint_maxp(desc);
        nt = usb_endpoint_maxp_mult(desc) - 1;
        buffer_size = GR_BUFFER_SIZE(epctrl);
        if (nt && (mode == 0 || mode == 2)) {
                dev_err(dev->dev,
                        "%s mode: multiple trans./microframe not valid\n",
                        (mode == 2 ? "Bulk" : "Control"));
                return -EINVAL;
        } else if (nt == 0x3) {
                dev_err(dev->dev,
                        "Invalid value 0x3 for additional trans./microframe\n");
                return -EINVAL;
        } else if ((nt + 1) * max > buffer_size) {
                dev_err(dev->dev, "Hw buffer size %d < max payload %d * %d\n",
                        buffer_size, (nt + 1), max);
                return -EINVAL;
        } else if (max == 0) {
                dev_err(dev->dev, "Max payload cannot be set to 0\n");
                return -EINVAL;
        } else if (max > ep->ep.maxpacket_limit) {
                dev_err(dev->dev, "Requested max payload %d > limit %d\n",
                        max, ep->ep.maxpacket_limit);
                return -EINVAL;
        }

        spin_lock(&ep->dev->lock);

        if (!ep->stopped) {
                spin_unlock(&ep->dev->lock);
                return -EBUSY;
        }

        ep->stopped = 0;
        ep->wedged = 0;
        ep->ep.desc = desc;
        ep->ep.maxpacket = max;
        ep->dma_start = 0;


        if (nt) {
                /*
                 * Maximum possible size of all payloads in one microframe
                 * regardless of direction when using high-bandwidth mode.
                 */
                ep->bytes_per_buffer = (nt + 1) * max;
        } else if (ep->is_in) {
                /*
                 * The biggest multiple of maximum packet size that fits into
                 * the buffer. The hardware will split up into many packets in
                 * the IN direction.
                 */
                ep->bytes_per_buffer = (buffer_size / max) * max;
        } else {
                /*
                 * Only single packets will be placed the buffers in the OUT
                 * direction.
                 */
                ep->bytes_per_buffer = max;
        }

        epctrl = (max << GR_EPCTRL_MAXPL_POS)
                | (nt << GR_EPCTRL_NT_POS)
                | (mode << GR_EPCTRL_TT_POS)
                | GR_EPCTRL_EV;
        if (ep->is_in)
                epctrl |= GR_EPCTRL_PI;
        gr_write32(&ep->regs->epctrl, epctrl);

        gr_write32(&ep->regs->dmactrl, GR_DMACTRL_IE | GR_DMACTRL_AI);

        spin_unlock(&ep->dev->lock);

        dev_dbg(ep->dev->dev, "EP: %s enabled - %s with %d bytes/buffer\n",
                ep->ep.name, gr_modestring[mode], ep->bytes_per_buffer);
        return 0;
}

/* Disable endpoint. Not for ep0in and ep0out that are handled separately. */
static int gr_ep_disable(struct usb_ep *_ep)
{
        struct gr_ep *ep;
        struct gr_udc *dev;
        unsigned long flags;

        ep = container_of(_ep, struct gr_ep, ep);
        if (!_ep || !ep->ep.desc)
                return -ENODEV;

        dev = ep->dev;

        /* 'ep0' IN and OUT are reserved */
        if (ep == &dev->epo[0] || ep == &dev->epi[0])
                return -EINVAL;

        if (dev->ep0state == GR_EP0_SUSPEND)
                return -EBUSY;

        dev_dbg(ep->dev->dev, "EP: disable %s\n", ep->ep.name);

        spin_lock_irqsave(&dev->lock, flags);

        gr_ep_nuke(ep);
        gr_ep_reset(ep);
        ep->ep.desc = NULL;

        spin_unlock_irqrestore(&dev->lock, flags);

        return 0;
}

/*
 * Frees a request, but not any DMA buffers associated with it
 * (gr_finish_request should already have taken care of that).
 */
static void gr_free_request(struct usb_ep *_ep, struct usb_request *_req)
{
        struct gr_request *req;

        if (!_ep || !_req)
                return;
        req = container_of(_req, struct gr_request, req);

        /* Leads to memory leak */
        WARN(!list_empty(&req->queue),
             "request not dequeued properly before freeing\n");

        kfree(req);
}

/* Queue a request from the gadget */
static int gr_queue_ext(struct usb_ep *_ep, struct usb_request *_req,
                        gfp_t gfp_flags)
{
        struct gr_ep *ep;
        struct gr_request *req;
        struct gr_udc *dev;
        int ret;

        if (unlikely(!_ep || !_req))
                return -EINVAL;

        ep = container_of(_ep, struct gr_ep, ep);
        req = container_of(_req, struct gr_request, req);
        dev = ep->dev;

        spin_lock(&ep->dev->lock);

        /*
         * The ep0 pointer in the gadget struct is used both for ep0in and
         * ep0out. In a data stage in the out direction ep0out needs to be used
         * instead of the default ep0in. Completion functions might use
         * driver_data, so that needs to be copied as well.
         */
        if ((ep == &dev->epi[0]) && (dev->ep0state == GR_EP0_ODATA)) {
                ep = &dev->epo[0];
                ep->ep.driver_data = dev->epi[0].ep.driver_data;
        }

        if (ep->is_in)
                gr_dbgprint_request("EXTERN", ep, req);

        ret = gr_queue(ep, req, GFP_ATOMIC);

        spin_unlock(&ep->dev->lock);

        return ret;
}

/* Dequeue JUST ONE request */
static int gr_dequeue(struct usb_ep *_ep, struct usb_request *_req)
{
        struct gr_request *req;
        struct gr_ep *ep;
        struct gr_udc *dev;
        int ret = 0;
        unsigned long flags;

        ep = container_of(_ep, struct gr_ep, ep);
        if (!_ep || !_req || (!ep->ep.desc && ep->num != 0))
                return -EINVAL;
        dev = ep->dev;
        if (!dev->driver)
                return -ESHUTDOWN;

        /* We can't touch (DMA) registers when suspended */
        if (dev->ep0state == GR_EP0_SUSPEND)
                return -EBUSY;

        spin_lock_irqsave(&dev->lock, flags);

        /* Make sure it's actually queued on this endpoint */
        list_for_each_entry(req, &ep->queue, queue) {
                if (&req->req == _req)
                        break;
        }
        if (&req->req != _req) {
                ret = -EINVAL;
                goto out;
        }

        if (list_first_entry(&ep->queue, struct gr_request, queue) == req) {
                /* This request is currently being processed */
                gr_abort_dma(ep);
                if (ep->stopped)
                        gr_finish_request(ep, req, -ECONNRESET);
                else
                        gr_dma_advance(ep, -ECONNRESET);
        } else if (!list_empty(&req->queue)) {
                /* Not being processed - gr_finish_request dequeues it */
                gr_finish_request(ep, req, -ECONNRESET);
        } else {
                ret = -EOPNOTSUPP;
        }

out:
        spin_unlock_irqrestore(&dev->lock, flags);

        return ret;
}

/* Helper for gr_set_halt and gr_set_wedge */
static int gr_set_halt_wedge(struct usb_ep *_ep, int halt, int wedge)
{
        int ret;
        struct gr_ep *ep;

        if (!_ep)
                return -ENODEV;
        ep = container_of(_ep, struct gr_ep, ep);

        spin_lock(&ep->dev->lock);

        /* Halting an IN endpoint should fail if queue is not empty */
        if (halt && ep->is_in && !list_empty(&ep->queue)) {
                ret = -EAGAIN;
                goto out;
        }

        ret = gr_ep_halt_wedge(ep, halt, wedge, 0);

out:
        spin_unlock(&ep->dev->lock);

        return ret;
}

/* Halt endpoint */
static int gr_set_halt(struct usb_ep *_ep, int halt)
{
        return gr_set_halt_wedge(_ep, halt, 0);
}

/* Halt and wedge endpoint */
static int gr_set_wedge(struct usb_ep *_ep)
{
        return gr_set_halt_wedge(_ep, 1, 1);
}

/*
 * Return the total number of bytes currently stored in the internal buffers of
 * the endpoint.
 */
static int gr_fifo_status(struct usb_ep *_ep)
{
        struct gr_ep *ep;
        u32 epstat;
        u32 bytes = 0;

        if (!_ep)
                return -ENODEV;
        ep = container_of(_ep, struct gr_ep, ep);

        epstat = gr_read32(&ep->regs->epstat);

        if (epstat & GR_EPSTAT_B0)
                bytes += (epstat & GR_EPSTAT_B0CNT_MASK) >> GR_EPSTAT_B0CNT_POS;
        if (epstat & GR_EPSTAT_B1)
                bytes += (epstat & GR_EPSTAT_B1CNT_MASK) >> GR_EPSTAT_B1CNT_POS;

        return bytes;
}


/* Empty data from internal buffers of an endpoint. */
static void gr_fifo_flush(struct usb_ep *_ep)
{
        struct gr_ep *ep;
        u32 epctrl;

        if (!_ep)
                return;
        ep = container_of(_ep, struct gr_ep, ep);
        dev_vdbg(ep->dev->dev, "EP: flush fifo %s\n", ep->ep.name);

        spin_lock(&ep->dev->lock);

        epctrl = gr_read32(&ep->regs->epctrl);
        epctrl |= GR_EPCTRL_CB;
        gr_write32(&ep->regs->epctrl, epctrl);

        spin_unlock(&ep->dev->lock);
}

static const struct usb_ep_ops gr_ep_ops = {
        .enable         = gr_ep_enable,
        .disable        = gr_ep_disable,

        .alloc_request  = gr_alloc_request,
        .free_request   = gr_free_request,

        .queue          = gr_queue_ext,
        .dequeue        = gr_dequeue,

        .set_halt       = gr_set_halt,
        .set_wedge      = gr_set_wedge,
        .fifo_status    = gr_fifo_status,
        .fifo_flush     = gr_fifo_flush,
};

/* ---------------------------------------------------------------------- */
/* USB Gadget ops */

static int gr_get_frame(struct usb_gadget *_gadget)
{
        struct gr_udc *dev;

        if (!_gadget)
                return -ENODEV;
        dev = container_of(_gadget, struct gr_udc, gadget);
        return gr_read32(&dev->regs->status) & GR_STATUS_FN_MASK;
}

static int gr_wakeup(struct usb_gadget *_gadget)
{
        struct gr_udc *dev;

        if (!_gadget)
                return -ENODEV;
        dev = container_of(_gadget, struct gr_udc, gadget);

        /* Remote wakeup feature not enabled by host*/
        if (!dev->remote_wakeup)
                return -EINVAL;

        spin_lock(&dev->lock);

        gr_write32(&dev->regs->control,
                   gr_read32(&dev->regs->control) | GR_CONTROL_RW);

        spin_unlock(&dev->lock);

        return 0;
}

static int gr_pullup(struct usb_gadget *_gadget, int is_on)
{
        struct gr_udc *dev;
        u32 control;

        if (!_gadget)
                return -ENODEV;
        dev = container_of(_gadget, struct gr_udc, gadget);

        spin_lock(&dev->lock);

        control = gr_read32(&dev->regs->control);
        if (is_on)
                control |= GR_CONTROL_EP;
        else
                control &= ~GR_CONTROL_EP;
        gr_write32(&dev->regs->control, control);

        spin_unlock(&dev->lock);

        return 0;
}

static int gr_udc_start(struct usb_gadget *gadget,
                        struct usb_gadget_driver *driver)
{
        struct gr_udc *dev = to_gr_udc(gadget);

        spin_lock(&dev->lock);

        /* Hook up the driver */
        driver->driver.bus = NULL;
        dev->driver = driver;

        /* Get ready for host detection */
        gr_enable_vbus_detect(dev);

        spin_unlock(&dev->lock);

        return 0;
}

static int gr_udc_stop(struct usb_gadget *gadget)
{
        struct gr_udc *dev = to_gr_udc(gadget);
        unsigned long flags;

        spin_lock_irqsave(&dev->lock, flags);

        dev->driver = NULL;
        gr_stop_activity(dev);

        spin_unlock_irqrestore(&dev->lock, flags);

        return 0;
}

static const struct usb_gadget_ops gr_ops = {
        .get_frame      = gr_get_frame,
        .wakeup         = gr_wakeup,
        .pullup         = gr_pullup,
        .udc_start      = gr_udc_start,
        .udc_stop       = gr_udc_stop,
        /* Other operations not supported */
};

/* ---------------------------------------------------------------------- */
/* Module probe, removal and of-matching */

static const char * const onames[] = {
        "ep0out", "ep1out", "ep2out", "ep3out", "ep4out", "ep5out",
        "ep6out", "ep7out", "ep8out", "ep9out", "ep10out", "ep11out",
        "ep12out", "ep13out", "ep14out", "ep15out"
};

static const char * const inames[] = {
        "ep0in", "ep1in", "ep2in", "ep3in", "ep4in", "ep5in",
        "ep6in", "ep7in", "ep8in", "ep9in", "ep10in", "ep11in",
        "ep12in", "ep13in", "ep14in", "ep15in"
};

/* Must be called with dev->lock held */
static int gr_ep_init(struct gr_udc *dev, int num, int is_in, u32 maxplimit)
{
        struct gr_ep *ep;
        struct gr_request *req;
        struct usb_request *_req;
        void *buf;

        if (is_in) {
                ep = &dev->epi[num];
                ep->ep.name = inames[num];
                ep->regs = &dev->regs->epi[num];
        } else {
                ep = &dev->epo[num];
                ep->ep.name = onames[num];
                ep->regs = &dev->regs->epo[num];
        }

        gr_ep_reset(ep);
        ep->num = num;
        ep->is_in = is_in;
        ep->dev = dev;
        ep->ep.ops = &gr_ep_ops;
        INIT_LIST_HEAD(&ep->queue);

        if (num == 0) {
                _req = gr_alloc_request(&ep->ep, GFP_ATOMIC);
                buf = devm_kzalloc(dev->dev, PAGE_SIZE, GFP_DMA | GFP_ATOMIC);
                if (!_req || !buf) {

                        /* possible _req freed by gr_probe via gr_remove */
                        return -ENOMEM;
                }

                req = container_of(_req, struct gr_request, req);
                req->req.buf = buf;
                req->req.length = MAX_CTRL_PL_SIZE;

                if (is_in)
                        dev->ep0reqi = req; /* Complete gets set as used */
                else
                        dev->ep0reqo = req; /* Completion treated separately */

                usb_ep_set_maxpacket_limit(&ep->ep, MAX_CTRL_PL_SIZE);
                ep->bytes_per_buffer = MAX_CTRL_PL_SIZE;

                ep->ep.caps.type_control = true;
        } else {
                usb_ep_set_maxpacket_limit(&ep->ep, (u16)maxplimit);
                list_add_tail(&ep->ep.ep_list, &dev->gadget.ep_list);

                ep->ep.caps.type_iso = true;
                ep->ep.caps.type_bulk = true;
                ep->ep.caps.type_int = true;
        }
        list_add_tail(&ep->ep_list, &dev->ep_list);

        if (is_in)
                ep->ep.caps.dir_in = true;
        else
                ep->ep.caps.dir_out = true;

        ep->tailbuf = dma_alloc_coherent(dev->dev, ep->ep.maxpacket_limit,
                                         &ep->tailbuf_paddr, GFP_ATOMIC);
        if (!ep->tailbuf)
                return -ENOMEM;

        return 0;
}

/* Must be called with dev->lock held */
static int gr_udc_init(struct gr_udc *dev)
{
        struct device_node *np = dev->dev->of_node;
        u32 epctrl_val;
        u32 dmactrl_val;
        int i;
        int ret = 0;
        u32 bufsize;

        gr_set_address(dev, 0);

        INIT_LIST_HEAD(&dev->gadget.ep_list);
        dev->gadget.speed = USB_SPEED_UNKNOWN;
        dev->gadget.ep0 = &dev->epi[0].ep;

        INIT_LIST_HEAD(&dev->ep_list);
        gr_set_ep0state(dev, GR_EP0_DISCONNECT);

        for (i = 0; i < dev->nepo; i++) {
                if (of_property_read_u32_index(np, "epobufsizes", i, &bufsize))
                        bufsize = 1024;
                ret = gr_ep_init(dev, i, 0, bufsize);
                if (ret)
                        return ret;
        }

        for (i = 0; i < dev->nepi; i++) {
                if (of_property_read_u32_index(np, "epibufsizes", i, &bufsize))
                        bufsize = 1024;
                ret = gr_ep_init(dev, i, 1, bufsize);
                if (ret)
                        return ret;
        }

        /* Must be disabled by default */
        dev->remote_wakeup = 0;

        /* Enable ep0out and ep0in */
        epctrl_val = (MAX_CTRL_PL_SIZE << GR_EPCTRL_MAXPL_POS) | GR_EPCTRL_EV;
        dmactrl_val = GR_DMACTRL_IE | GR_DMACTRL_AI;
        gr_write32(&dev->epo[0].regs->epctrl, epctrl_val);
        gr_write32(&dev->epi[0].regs->epctrl, epctrl_val | GR_EPCTRL_PI);
        gr_write32(&dev->epo[0].regs->dmactrl, dmactrl_val);
        gr_write32(&dev->epi[0].regs->dmactrl, dmactrl_val);

        return 0;
}

static void gr_ep_remove(struct gr_udc *dev, int num, int is_in)
{
        struct gr_ep *ep;

        if (is_in)
                ep = &dev->epi[num];
        else
                ep = &dev->epo[num];

        if (ep->tailbuf)
                dma_free_coherent(dev->dev, ep->ep.maxpacket_limit,
                                  ep->tailbuf, ep->tailbuf_paddr);
}

static int gr_remove(struct platform_device *pdev)
{
        struct gr_udc *dev = platform_get_drvdata(pdev);
        int i;

        if (dev->added)
                usb_del_gadget_udc(&dev->gadget); /* Shuts everything down */
        if (dev->driver)
                return -EBUSY;

        gr_dfs_delete(dev);
        dma_pool_destroy(dev->desc_pool);
        platform_set_drvdata(pdev, NULL);

        gr_free_request(&dev->epi[0].ep, &dev->ep0reqi->req);
        gr_free_request(&dev->epo[0].ep, &dev->ep0reqo->req);

        for (i = 0; i < dev->nepo; i++)
                gr_ep_remove(dev, i, 0);
        for (i = 0; i < dev->nepi; i++)
                gr_ep_remove(dev, i, 1);

        return 0;
}
static int gr_request_irq(struct gr_udc *dev, int irq)
{
        return devm_request_threaded_irq(dev->dev, irq, gr_irq, gr_irq_handler,
                                         IRQF_SHARED, driver_name, dev);
}

static int gr_probe(struct platform_device *pdev)
{
        struct gr_udc *dev;
        struct resource *res;
        struct gr_regs __iomem *regs;
        int retval;
        u32 status;

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

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        regs = devm_ioremap_resource(dev->dev, res);
        if (IS_ERR(regs))
                return PTR_ERR(regs);

        dev->irq = platform_get_irq(pdev, 0);
        if (dev->irq <= 0) {
                dev_err(dev->dev, "No irq found\n");
                return -ENODEV;
        }

        /* Some core configurations has separate irqs for IN and OUT events */
        dev->irqi = platform_get_irq(pdev, 1);
        if (dev->irqi > 0) {
                dev->irqo = platform_get_irq(pdev, 2);
                if (dev->irqo <= 0) {
                        dev_err(dev->dev, "Found irqi but not irqo\n");
                        return -ENODEV;
                }
        } else {
                dev->irqi = 0;
        }

        dev->gadget.name = driver_name;
        dev->gadget.max_speed = USB_SPEED_HIGH;
        dev->gadget.ops = &gr_ops;

        spin_lock_init(&dev->lock);
        dev->regs = regs;

        platform_set_drvdata(pdev, dev);

        /* Determine number of endpoints and data interface mode */
        status = gr_read32(&dev->regs->status);
        dev->nepi = ((status & GR_STATUS_NEPI_MASK) >> GR_STATUS_NEPI_POS) + 1;
        dev->nepo = ((status & GR_STATUS_NEPO_MASK) >> GR_STATUS_NEPO_POS) + 1;

        if (!(status & GR_STATUS_DM)) {
                dev_err(dev->dev, "Slave mode cores are not supported\n");
                return -ENODEV;
        }

        /* --- Effects of the following calls might need explicit cleanup --- */

        /* Create DMA pool for descriptors */
        dev->desc_pool = dma_pool_create("desc_pool", dev->dev,
                                         sizeof(struct gr_dma_desc), 4, 0);
        if (!dev->desc_pool) {
                dev_err(dev->dev, "Could not allocate DMA pool");
                return -ENOMEM;
        }

        spin_lock(&dev->lock);

        /* Inside lock so that no gadget can use this udc until probe is done */
        retval = usb_add_gadget_udc(dev->dev, &dev->gadget);
        if (retval) {
                dev_err(dev->dev, "Could not add gadget udc");
                goto out;
        }
        dev->added = 1;

        retval = gr_udc_init(dev);
        if (retval)
                goto out;

        gr_dfs_create(dev);

        /* Clear all interrupt enables that might be left on since last boot */
        gr_disable_interrupts_and_pullup(dev);

        retval = gr_request_irq(dev, dev->irq);
        if (retval) {
                dev_err(dev->dev, "Failed to request irq %d\n", dev->irq);
                goto out;
        }

        if (dev->irqi) {
                retval = gr_request_irq(dev, dev->irqi);
                if (retval) {
                        dev_err(dev->dev, "Failed to request irqi %d\n",
                                dev->irqi);
                        goto out;
                }
                retval = gr_request_irq(dev, dev->irqo);
                if (retval) {
                        dev_err(dev->dev, "Failed to request irqo %d\n",
                                dev->irqo);
                        goto out;
                }
        }

        if (dev->irqi)
                dev_info(dev->dev, "regs: %p, irqs %d, %d, %d\n", dev->regs,
                         dev->irq, dev->irqi, dev->irqo);
        else
                dev_info(dev->dev, "regs: %p, irq %d\n", dev->regs, dev->irq);

out:
        spin_unlock(&dev->lock);

        if (retval)
                gr_remove(pdev);

        return retval;
}

static const struct of_device_id gr_match[] = {
        {.name = "GAISLER_USBDC"},
        {.name = "01_021"},
        {},
};
MODULE_DEVICE_TABLE(of, gr_match);

static struct platform_driver gr_driver = {
        .driver = {
                .name = DRIVER_NAME,
                .of_match_table = gr_match,
        },
        .probe = gr_probe,
        .remove = gr_remove,
};
module_platform_driver(gr_driver);

MODULE_AUTHOR("Aeroflex Gaisler AB.");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");