/*
 * at91_udc -- driver for at91-series USB peripheral controller
 *
 * Copyright (C) 2004 by Thomas Rathbone
 * Copyright (C) 2005 by HP Labs
 * Copyright (C) 2005 by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#undef  VERBOSE_DEBUG
#undef  PACKET_TRACE

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/list.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/prefetch.h>
#include <linux/clk.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/platform_data/atmel.h>

#include <asm/byteorder.h>
#include <mach/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/gpio.h>

#include <mach/cpu.h>
#include <mach/at91sam9261_matrix.h>
#include <mach/at91_matrix.h>

#include "at91_udc.h"


/*
 * This controller is simple and PIO-only.  It's used in many AT91-series
 * full speed USB controllers, including the at91rm9200 (arm920T, with MMU),
 * at91sam926x (arm926ejs, with MMU), and several no-mmu versions.
 *
 * This driver expects the board has been wired with two GPIOs supporting
 * a VBUS sensing IRQ, and a D+ pullup.  (They may be omitted, but the
 * testing hasn't covered such cases.)
 *
 * The pullup is most important (so it's integrated on sam926x parts).  It
 * provides software control over whether the host enumerates the device.
 *
 * The VBUS sensing helps during enumeration, and allows both USB clocks
 * (and the transceiver) to stay gated off until they're necessary, saving
 * power.  During USB suspend, the 48 MHz clock is gated off in hardware;
 * it may also be gated off by software during some Linux sleep states.
 */

#define DRIVER_VERSION  "3 May 2006"

static const char driver_name [] = "at91_udc";
static const char ep0name[] = "ep0";

#define VBUS_POLL_TIMEOUT       msecs_to_jiffies(1000)

#define at91_udp_read(udc, reg) \
        __raw_readl((udc)->udp_baseaddr + (reg))
#define at91_udp_write(udc, reg, val) \
        __raw_writel((val), (udc)->udp_baseaddr + (reg))

/*-------------------------------------------------------------------------*/

#ifdef CONFIG_USB_GADGET_DEBUG_FILES

#include <linux/seq_file.h>

static const char debug_filename[] = "driver/udc";

#define FOURBITS "%s%s%s%s"
#define EIGHTBITS FOURBITS FOURBITS

static void proc_ep_show(struct seq_file *s, struct at91_ep *ep)
{
        static char             *types[] = {
                "control", "out-iso", "out-bulk", "out-int",
                "BOGUS",   "in-iso",  "in-bulk",  "in-int"};

        u32                     csr;
        struct at91_request     *req;
        unsigned long   flags;
        struct at91_udc *udc = ep->udc;

        spin_lock_irqsave(&udc->lock, flags);

        csr = __raw_readl(ep->creg);

        /* NOTE:  not collecting per-endpoint irq statistics... */

        seq_printf(s, "\n");
        seq_printf(s, "%s, maxpacket %d %s%s %s%s\n",
                        ep->ep.name, ep->ep.maxpacket,
                        ep->is_in ? "in" : "out",
                        ep->is_iso ? " iso" : "",
                        ep->is_pingpong
                                ? (ep->fifo_bank ? "pong" : "ping")
                                : "",
                        ep->stopped ? " stopped" : "");
        seq_printf(s, "csr %08x rxbytes=%d %s %s %s" EIGHTBITS "\n",
                csr,
                (csr & 0x07ff0000) >> 16,
                (csr & (1 << 15)) ? "enabled" : "disabled",
                (csr & (1 << 11)) ? "DATA1" : "DATA0",
                types[(csr & 0x700) >> 8],

                /* iff type is control then print current direction */
                (!(csr & 0x700))
                        ? ((csr & (1 << 7)) ? " IN" : " OUT")
                        : "",
                (csr & (1 << 6)) ? " rxdatabk1" : "",
                (csr & (1 << 5)) ? " forcestall" : "",
                (csr & (1 << 4)) ? " txpktrdy" : "",

                (csr & (1 << 3)) ? " stallsent" : "",
                (csr & (1 << 2)) ? " rxsetup" : "",
                (csr & (1 << 1)) ? " rxdatabk0" : "",
                (csr & (1 << 0)) ? " txcomp" : "");
        if (list_empty (&ep->queue))
                seq_printf(s, "\t(queue empty)\n");

        else list_for_each_entry (req, &ep->queue, queue) {
                unsigned        length = req->req.actual;

                seq_printf(s, "\treq %p len %d/%d buf %p\n",
                                &req->req, length,
                                req->req.length, req->req.buf);
        }
        spin_unlock_irqrestore(&udc->lock, flags);
}

static void proc_irq_show(struct seq_file *s, const char *label, u32 mask)
{
        int i;

        seq_printf(s, "%s %04x:%s%s" FOURBITS, label, mask,
                (mask & (1 << 13)) ? " wakeup" : "",
                (mask & (1 << 12)) ? " endbusres" : "",

                (mask & (1 << 11)) ? " sofint" : "",
                (mask & (1 << 10)) ? " extrsm" : "",
                (mask & (1 << 9)) ? " rxrsm" : "",
                (mask & (1 << 8)) ? " rxsusp" : "");
        for (i = 0; i < 8; i++) {
                if (mask & (1 << i))
                        seq_printf(s, " ep%d", i);
        }
        seq_printf(s, "\n");
}

static int proc_udc_show(struct seq_file *s, void *unused)
{
        struct at91_udc *udc = s->private;
        struct at91_ep  *ep;
        u32             tmp;

        seq_printf(s, "%s: version %s\n", driver_name, DRIVER_VERSION);

        seq_printf(s, "vbus %s, pullup %s, %s powered%s, gadget %s\n\n",
                udc->vbus ? "present" : "off",
                udc->enabled
                        ? (udc->vbus ? "active" : "enabled")
                        : "disabled",
                udc->selfpowered ? "self" : "VBUS",
                udc->suspended ? ", suspended" : "",
                udc->driver ? udc->driver->driver.name : "(none)");

        /* don't access registers when interface isn't clocked */
        if (!udc->clocked) {
                seq_printf(s, "(not clocked)\n");
                return 0;
        }

        tmp = at91_udp_read(udc, AT91_UDP_FRM_NUM);
        seq_printf(s, "frame %05x:%s%s frame=%d\n", tmp,
                (tmp & AT91_UDP_FRM_OK) ? " ok" : "",
                (tmp & AT91_UDP_FRM_ERR) ? " err" : "",
                (tmp & AT91_UDP_NUM));

        tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
        seq_printf(s, "glbstate %02x:%s" FOURBITS "\n", tmp,
                (tmp & AT91_UDP_RMWUPE) ? " rmwupe" : "",
                (tmp & AT91_UDP_RSMINPR) ? " rsminpr" : "",
                (tmp & AT91_UDP_ESR) ? " esr" : "",
                (tmp & AT91_UDP_CONFG) ? " confg" : "",
                (tmp & AT91_UDP_FADDEN) ? " fadden" : "");

        tmp = at91_udp_read(udc, AT91_UDP_FADDR);
        seq_printf(s, "faddr   %03x:%s fadd=%d\n", tmp,
                (tmp & AT91_UDP_FEN) ? " fen" : "",
                (tmp & AT91_UDP_FADD));

        proc_irq_show(s, "imr   ", at91_udp_read(udc, AT91_UDP_IMR));
        proc_irq_show(s, "isr   ", at91_udp_read(udc, AT91_UDP_ISR));

        if (udc->enabled && udc->vbus) {
                proc_ep_show(s, &udc->ep[0]);
                list_for_each_entry (ep, &udc->gadget.ep_list, ep.ep_list) {
                        if (ep->ep.desc)
                                proc_ep_show(s, ep);
                }
        }
        return 0;
}

static int proc_udc_open(struct inode *inode, struct file *file)
{
        return single_open(file, proc_udc_show, PDE_DATA(inode));
}

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

static void create_debug_file(struct at91_udc *udc)
{
        udc->pde = proc_create_data(debug_filename, 0, NULL, &proc_ops, udc);
}

static void remove_debug_file(struct at91_udc *udc)
{
        if (udc->pde)
                remove_proc_entry(debug_filename, NULL);
}

#else

static inline void create_debug_file(struct at91_udc *udc) {}
static inline void remove_debug_file(struct at91_udc *udc) {}

#endif


/*-------------------------------------------------------------------------*/

static void done(struct at91_ep *ep, struct at91_request *req, int status)
{
        unsigned        stopped = ep->stopped;
        struct at91_udc *udc = ep->udc;

        list_del_init(&req->queue);
        if (req->req.status == -EINPROGRESS)
                req->req.status = status;
        else
                status = req->req.status;
        if (status && status != -ESHUTDOWN)
                VDBG("%s done %p, status %d\n", ep->ep.name, req, status);

        ep->stopped = 1;
        spin_unlock(&udc->lock);
        req->req.complete(&ep->ep, &req->req);
        spin_lock(&udc->lock);
        ep->stopped = stopped;

        /* ep0 is always ready; other endpoints need a non-empty queue */
        if (list_empty(&ep->queue) && ep->int_mask != (1 << 0))
                at91_udp_write(udc, AT91_UDP_IDR, ep->int_mask);
}

/*-------------------------------------------------------------------------*/

/* bits indicating OUT fifo has data ready */
#define RX_DATA_READY   (AT91_UDP_RX_DATA_BK0 | AT91_UDP_RX_DATA_BK1)

/*
 * Endpoint FIFO CSR bits have a mix of bits, making it unsafe to just write
 * back most of the value you just read (because of side effects, including
 * bits that may change after reading and before writing).
 *
 * Except when changing a specific bit, always write values which:
 *  - clear SET_FX bits (setting them could change something)
 *  - set CLR_FX bits (clearing them could change something)
 *
 * There are also state bits like FORCESTALL, EPEDS, DIR, and EPTYPE
 * that shouldn't normally be changed.
 *
 * NOTE at91sam9260 docs mention synch between UDPCK and MCK clock domains,
 * implying a need to wait for one write to complete (test relevant bits)
 * before starting the next write.  This shouldn't be an issue given how
 * infrequently we write, except maybe for write-then-read idioms.
 */
#define SET_FX  (AT91_UDP_TXPKTRDY)
#define CLR_FX  (RX_DATA_READY | AT91_UDP_RXSETUP \
                | AT91_UDP_STALLSENT | AT91_UDP_TXCOMP)

/* pull OUT packet data from the endpoint's fifo */
static int read_fifo (struct at91_ep *ep, struct at91_request *req)
{
        u32 __iomem     *creg = ep->creg;
        u8 __iomem      *dreg = ep->creg + (AT91_UDP_FDR(0) - AT91_UDP_CSR(0));
        u32             csr;
        u8              *buf;
        unsigned int    count, bufferspace, is_done;

        buf = req->req.buf + req->req.actual;
        bufferspace = req->req.length - req->req.actual;

        /*
         * there might be nothing to read if ep_queue() calls us,
         * or if we already emptied both pingpong buffers
         */
rescan:
        csr = __raw_readl(creg);
        if ((csr & RX_DATA_READY) == 0)
                return 0;

        count = (csr & AT91_UDP_RXBYTECNT) >> 16;
        if (count > ep->ep.maxpacket)
                count = ep->ep.maxpacket;
        if (count > bufferspace) {
                DBG("%s buffer overflow\n", ep->ep.name);
                req->req.status = -EOVERFLOW;
                count = bufferspace;
        }
        __raw_readsb(dreg, buf, count);

        /* release and swap pingpong mem bank */
        csr |= CLR_FX;
        if (ep->is_pingpong) {
                if (ep->fifo_bank == 0) {
                        csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK0);
                        ep->fifo_bank = 1;
                } else {
                        csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK1);
                        ep->fifo_bank = 0;
                }
        } else
                csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK0);
        __raw_writel(csr, creg);

        req->req.actual += count;
        is_done = (count < ep->ep.maxpacket);
        if (count == bufferspace)
                is_done = 1;

        PACKET("%s %p out/%d%s\n", ep->ep.name, &req->req, count,
                        is_done ? " (done)" : "");

        /*
         * avoid extra trips through IRQ logic for packets already in
         * the fifo ... maybe preventing an extra (expensive) OUT-NAK
         */
        if (is_done)
                done(ep, req, 0);
        else if (ep->is_pingpong) {
                /*
                 * One dummy read to delay the code because of a HW glitch:
                 * CSR returns bad RXCOUNT when read too soon after updating
                 * RX_DATA_BK flags.
                 */
                csr = __raw_readl(creg);

                bufferspace -= count;
                buf += count;
                goto rescan;
        }

        return is_done;
}

/* load fifo for an IN packet */
static int write_fifo(struct at91_ep *ep, struct at91_request *req)
{
        u32 __iomem     *creg = ep->creg;
        u32             csr = __raw_readl(creg);
        u8 __iomem      *dreg = ep->creg + (AT91_UDP_FDR(0) - AT91_UDP_CSR(0));
        unsigned        total, count, is_last;
        u8              *buf;

        /*
         * TODO: allow for writing two packets to the fifo ... that'll
         * reduce the amount of IN-NAKing, but probably won't affect
         * throughput much.  (Unlike preventing OUT-NAKing!)
         */

        /*
         * If ep_queue() calls us, the queue is empty and possibly in
         * odd states like TXCOMP not yet cleared (we do it, saving at
         * least one IRQ) or the fifo not yet being free.  Those aren't
         * issues normally (IRQ handler fast path).
         */
        if (unlikely(csr & (AT91_UDP_TXCOMP | AT91_UDP_TXPKTRDY))) {
                if (csr & AT91_UDP_TXCOMP) {
                        csr |= CLR_FX;
                        csr &= ~(SET_FX | AT91_UDP_TXCOMP);
                        __raw_writel(csr, creg);
                        csr = __raw_readl(creg);
                }
                if (csr & AT91_UDP_TXPKTRDY)
                        return 0;
        }

        buf = req->req.buf + req->req.actual;
        prefetch(buf);
        total = req->req.length - req->req.actual;
        if (ep->ep.maxpacket < total) {
                count = ep->ep.maxpacket;
                is_last = 0;
        } else {
                count = total;
                is_last = (count < ep->ep.maxpacket) || !req->req.zero;
        }

        /*
         * Write the packet, maybe it's a ZLP.
         *
         * NOTE:  incrementing req->actual before we receive the ACK means
         * gadget driver IN bytecounts can be wrong in fault cases.  That's
         * fixable with PIO drivers like this one (save "count" here, and
         * do the increment later on TX irq), but not for most DMA hardware.
         *
         * So all gadget drivers must accept that potential error.  Some
         * hardware supports precise fifo status reporting, letting them
         * recover when the actual bytecount matters (e.g. for USB Test
         * and Measurement Class devices).
         */
        __raw_writesb(dreg, buf, count);
        csr &= ~SET_FX;
        csr |= CLR_FX | AT91_UDP_TXPKTRDY;
        __raw_writel(csr, creg);
        req->req.actual += count;

        PACKET("%s %p in/%d%s\n", ep->ep.name, &req->req, count,
                        is_last ? " (done)" : "");
        if (is_last)
                done(ep, req, 0);
        return is_last;
}

static void nuke(struct at91_ep *ep, int status)
{
        struct at91_request *req;

        /* terminate any request in the queue */
        ep->stopped = 1;
        if (list_empty(&ep->queue))
                return;

        VDBG("%s %s\n", __func__, ep->ep.name);
        while (!list_empty(&ep->queue)) {
                req = list_entry(ep->queue.next, struct at91_request, queue);
                done(ep, req, status);
        }
}

/*-------------------------------------------------------------------------*/

static int at91_ep_enable(struct usb_ep *_ep,
                                const struct usb_endpoint_descriptor *desc)
{
        struct at91_ep  *ep = container_of(_ep, struct at91_ep, ep);
        struct at91_udc *udc;
        u16             maxpacket;
        u32             tmp;
        unsigned long   flags;

        if (!_ep || !ep
                        || !desc || _ep->name == ep0name
                        || desc->bDescriptorType != USB_DT_ENDPOINT
                        || (maxpacket = usb_endpoint_maxp(desc)) == 0
                        || maxpacket > ep->maxpacket) {
                DBG("bad ep or descriptor\n");
                return -EINVAL;
        }

        udc = ep->udc;
        if (!udc->driver || udc->gadget.speed == USB_SPEED_UNKNOWN) {
                DBG("bogus device state\n");
                return -ESHUTDOWN;
        }

        tmp = usb_endpoint_type(desc);
        switch (tmp) {
        case USB_ENDPOINT_XFER_CONTROL:
                DBG("only one control endpoint\n");
                return -EINVAL;
        case USB_ENDPOINT_XFER_INT:
                if (maxpacket > 64)
                        goto bogus_max;
                break;
        case USB_ENDPOINT_XFER_BULK:
                switch (maxpacket) {
                case 8:
                case 16:
                case 32:
                case 64:
                        goto ok;
                }
bogus_max:
                DBG("bogus maxpacket %d\n", maxpacket);
                return -EINVAL;
        case USB_ENDPOINT_XFER_ISOC:
                if (!ep->is_pingpong) {
                        DBG("iso requires double buffering\n");
                        return -EINVAL;
                }
                break;
        }

ok:
        spin_lock_irqsave(&udc->lock, flags);

        /* initialize endpoint to match this descriptor */
        ep->is_in = usb_endpoint_dir_in(desc);
        ep->is_iso = (tmp == USB_ENDPOINT_XFER_ISOC);
        ep->stopped = 0;
        if (ep->is_in)
                tmp |= 0x04;
        tmp <<= 8;
        tmp |= AT91_UDP_EPEDS;
        __raw_writel(tmp, ep->creg);

        ep->ep.maxpacket = maxpacket;

        /*
         * reset/init endpoint fifo.  NOTE:  leaves fifo_bank alone,
         * since endpoint resets don't reset hw pingpong state.
         */
        at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
        at91_udp_write(udc, AT91_UDP_RST_EP, 0);

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

static int at91_ep_disable (struct usb_ep * _ep)
{
        struct at91_ep  *ep = container_of(_ep, struct at91_ep, ep);
        struct at91_udc *udc = ep->udc;
        unsigned long   flags;

        if (ep == &ep->udc->ep[0])
                return -EINVAL;

        spin_lock_irqsave(&udc->lock, flags);

        nuke(ep, -ESHUTDOWN);

        /* restore the endpoint's pristine config */
        ep->ep.desc = NULL;
        ep->ep.maxpacket = ep->maxpacket;

        /* reset fifos and endpoint */
        if (ep->udc->clocked) {
                at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
                at91_udp_write(udc, AT91_UDP_RST_EP, 0);
                __raw_writel(0, ep->creg);
        }

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

/*
 * this is a PIO-only driver, so there's nothing
 * interesting for request or buffer allocation.
 */

static struct usb_request *
at91_ep_alloc_request(struct usb_ep *_ep, gfp_t gfp_flags)
{
        struct at91_request *req;

        req = kzalloc(sizeof (struct at91_request), gfp_flags);
        if (!req)
                return NULL;

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

static void at91_ep_free_request(struct usb_ep *_ep, struct usb_request *_req)
{
        struct at91_request *req;

        req = container_of(_req, struct at91_request, req);
        BUG_ON(!list_empty(&req->queue));
        kfree(req);
}

static int at91_ep_queue(struct usb_ep *_ep,
                        struct usb_request *_req, gfp_t gfp_flags)
{
        struct at91_request     *req;
        struct at91_ep          *ep;
        struct at91_udc         *udc;
        int                     status;
        unsigned long           flags;

        req = container_of(_req, struct at91_request, req);
        ep = container_of(_ep, struct at91_ep, ep);

        if (!_req || !_req->complete
                        || !_req->buf || !list_empty(&req->queue)) {
                DBG("invalid request\n");
                return -EINVAL;
        }

        if (!_ep || (!ep->ep.desc && ep->ep.name != ep0name)) {
                DBG("invalid ep\n");
                return -EINVAL;
        }

        udc = ep->udc;

        if (!udc || !udc->driver || udc->gadget.speed == USB_SPEED_UNKNOWN) {
                DBG("invalid device\n");
                return -EINVAL;
        }

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

        spin_lock_irqsave(&udc->lock, flags);

        /* try to kickstart any empty and idle queue */
        if (list_empty(&ep->queue) && !ep->stopped) {
                int     is_ep0;

                /*
                 * If this control request has a non-empty DATA stage, this
                 * will start that stage.  It works just like a non-control
                 * request (until the status stage starts, maybe early).
                 *
                 * If the data stage is empty, then this starts a successful
                 * IN/STATUS stage.  (Unsuccessful ones use set_halt.)
                 */
                is_ep0 = (ep->ep.name == ep0name);
                if (is_ep0) {
                        u32     tmp;

                        if (!udc->req_pending) {
                                status = -EINVAL;
                                goto done;
                        }

                        /*
                         * defer changing CONFG until after the gadget driver
                         * reconfigures the endpoints.
                         */
                        if (udc->wait_for_config_ack) {
                                tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
                                tmp ^= AT91_UDP_CONFG;
                                VDBG("toggle config\n");
                                at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);
                        }
                        if (req->req.length == 0) {
ep0_in_status:
                                PACKET("ep0 in/status\n");
                                status = 0;
                                tmp = __raw_readl(ep->creg);
                                tmp &= ~SET_FX;
                                tmp |= CLR_FX | AT91_UDP_TXPKTRDY;
                                __raw_writel(tmp, ep->creg);
                                udc->req_pending = 0;
                                goto done;
                        }
                }

                if (ep->is_in)
                        status = write_fifo(ep, req);
                else {
                        status = read_fifo(ep, req);

                        /* IN/STATUS stage is otherwise triggered by irq */
                        if (status && is_ep0)
                                goto ep0_in_status;
                }
        } else
                status = 0;

        if (req && !status) {
                list_add_tail (&req->queue, &ep->queue);
                at91_udp_write(udc, AT91_UDP_IER, ep->int_mask);
        }
done:
        spin_unlock_irqrestore(&udc->lock, flags);
        return (status < 0) ? status : 0;
}

static int at91_ep_dequeue(struct usb_ep *_ep, struct usb_request *_req)
{
        struct at91_ep          *ep;
        struct at91_request     *req;
        unsigned long           flags;
        struct at91_udc         *udc;

        ep = container_of(_ep, struct at91_ep, ep);
        if (!_ep || ep->ep.name == ep0name)
                return -EINVAL;

        udc = ep->udc;

        spin_lock_irqsave(&udc->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) {
                spin_unlock_irqrestore(&udc->lock, flags);
                return -EINVAL;
        }

        done(ep, req, -ECONNRESET);
        spin_unlock_irqrestore(&udc->lock, flags);
        return 0;
}

static int at91_ep_set_halt(struct usb_ep *_ep, int value)
{
        struct at91_ep  *ep = container_of(_ep, struct at91_ep, ep);
        struct at91_udc *udc = ep->udc;
        u32 __iomem     *creg;
        u32             csr;
        unsigned long   flags;
        int             status = 0;

        if (!_ep || ep->is_iso || !ep->udc->clocked)
                return -EINVAL;

        creg = ep->creg;
        spin_lock_irqsave(&udc->lock, flags);

        csr = __raw_readl(creg);

        /*
         * fail with still-busy IN endpoints, ensuring correct sequencing
         * of data tx then stall.  note that the fifo rx bytecount isn't
         * completely accurate as a tx bytecount.
         */
        if (ep->is_in && (!list_empty(&ep->queue) || (csr >> 16) != 0))
                status = -EAGAIN;
        else {
                csr |= CLR_FX;
                csr &= ~SET_FX;
                if (value) {
                        csr |= AT91_UDP_FORCESTALL;
                        VDBG("halt %s\n", ep->ep.name);
                } else {
                        at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
                        at91_udp_write(udc, AT91_UDP_RST_EP, 0);
                        csr &= ~AT91_UDP_FORCESTALL;
                }
                __raw_writel(csr, creg);
        }

        spin_unlock_irqrestore(&udc->lock, flags);
        return status;
}

static const struct usb_ep_ops at91_ep_ops = {
        .enable         = at91_ep_enable,
        .disable        = at91_ep_disable,
        .alloc_request  = at91_ep_alloc_request,
        .free_request   = at91_ep_free_request,
        .queue          = at91_ep_queue,
        .dequeue        = at91_ep_dequeue,
        .set_halt       = at91_ep_set_halt,
        /* there's only imprecise fifo status reporting */
};

/*-------------------------------------------------------------------------*/

static int at91_get_frame(struct usb_gadget *gadget)
{
        struct at91_udc *udc = to_udc(gadget);

        if (!to_udc(gadget)->clocked)
                return -EINVAL;
        return at91_udp_read(udc, AT91_UDP_FRM_NUM) & AT91_UDP_NUM;
}

static int at91_wakeup(struct usb_gadget *gadget)
{
        struct at91_udc *udc = to_udc(gadget);
        u32             glbstate;
        int             status = -EINVAL;
        unsigned long   flags;

        DBG("%s\n", __func__ );
        spin_lock_irqsave(&udc->lock, flags);

        if (!udc->clocked || !udc->suspended)
                goto done;

        /* NOTE:  some "early versions" handle ESR differently ... */

        glbstate = at91_udp_read(udc, AT91_UDP_GLB_STAT);
        if (!(glbstate & AT91_UDP_ESR))
                goto done;
        glbstate |= AT91_UDP_ESR;
        at91_udp_write(udc, AT91_UDP_GLB_STAT, glbstate);

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

/* reinit == restore initial software state */
static void udc_reinit(struct at91_udc *udc)
{
        u32 i;

        INIT_LIST_HEAD(&udc->gadget.ep_list);
        INIT_LIST_HEAD(&udc->gadget.ep0->ep_list);

        for (i = 0; i < NUM_ENDPOINTS; i++) {
                struct at91_ep *ep = &udc->ep[i];

                if (i != 0)
                        list_add_tail(&ep->ep.ep_list, &udc->gadget.ep_list);
                ep->ep.desc = NULL;
                ep->stopped = 0;
                ep->fifo_bank = 0;
                usb_ep_set_maxpacket_limit(&ep->ep, ep->maxpacket);
                ep->creg = (void __iomem *) udc->udp_baseaddr + AT91_UDP_CSR(i);
                /* initialize one queue per endpoint */
                INIT_LIST_HEAD(&ep->queue);
        }
}

static void stop_activity(struct at91_udc *udc)
{
        struct usb_gadget_driver *driver = udc->driver;
        int i;

        if (udc->gadget.speed == USB_SPEED_UNKNOWN)
                driver = NULL;
        udc->gadget.speed = USB_SPEED_UNKNOWN;
        udc->suspended = 0;

        for (i = 0; i < NUM_ENDPOINTS; i++) {
                struct at91_ep *ep = &udc->ep[i];
                ep->stopped = 1;
                nuke(ep, -ESHUTDOWN);
        }
        if (driver) {
                spin_unlock(&udc->lock);
                driver->disconnect(&udc->gadget);
                spin_lock(&udc->lock);
        }

        udc_reinit(udc);
}

static void clk_on(struct at91_udc *udc)
{
        if (udc->clocked)
                return;
        udc->clocked = 1;

        if (IS_ENABLED(CONFIG_COMMON_CLK)) {
                clk_set_rate(udc->uclk, 48000000);
                clk_prepare_enable(udc->uclk);
        }
        clk_prepare_enable(udc->iclk);
        clk_prepare_enable(udc->fclk);
}

static void clk_off(struct at91_udc *udc)
{
        if (!udc->clocked)
                return;
        udc->clocked = 0;
        udc->gadget.speed = USB_SPEED_UNKNOWN;
        clk_disable_unprepare(udc->fclk);
        clk_disable_unprepare(udc->iclk);
        if (IS_ENABLED(CONFIG_COMMON_CLK))
                clk_disable_unprepare(udc->uclk);
}

/*
 * activate/deactivate link with host; minimize power usage for
 * inactive links by cutting clocks and transceiver power.
 */
static void pullup(struct at91_udc *udc, int is_on)
{
        int     active = !udc->board.pullup_active_low;

        if (!udc->enabled || !udc->vbus)
                is_on = 0;
        DBG("%sactive\n", is_on ? "" : "in");

        if (is_on) {
                clk_on(udc);
                at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXRSM);
                at91_udp_write(udc, AT91_UDP_TXVC, 0);
                if (cpu_is_at91rm9200())
                        gpio_set_value(udc->board.pullup_pin, active);
                else if (cpu_is_at91sam9260() || cpu_is_at91sam9263() || cpu_is_at91sam9g20()) {
                        u32     txvc = at91_udp_read(udc, AT91_UDP_TXVC);

                        txvc |= AT91_UDP_TXVC_PUON;
                        at91_udp_write(udc, AT91_UDP_TXVC, txvc);
                } else if (cpu_is_at91sam9261() || cpu_is_at91sam9g10()) {
                        u32     usbpucr;

                        usbpucr = at91_matrix_read(AT91_MATRIX_USBPUCR);
                        usbpucr |= AT91_MATRIX_USBPUCR_PUON;
                        at91_matrix_write(AT91_MATRIX_USBPUCR, usbpucr);
                }
        } else {
                stop_activity(udc);
                at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXRSM);
                at91_udp_write(udc, AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
                if (cpu_is_at91rm9200())
                        gpio_set_value(udc->board.pullup_pin, !active);
                else if (cpu_is_at91sam9260() || cpu_is_at91sam9263() || cpu_is_at91sam9g20()) {
                        u32     txvc = at91_udp_read(udc, AT91_UDP_TXVC);

                        txvc &= ~AT91_UDP_TXVC_PUON;
                        at91_udp_write(udc, AT91_UDP_TXVC, txvc);
                } else if (cpu_is_at91sam9261() || cpu_is_at91sam9g10()) {
                        u32     usbpucr;

                        usbpucr = at91_matrix_read(AT91_MATRIX_USBPUCR);
                        usbpucr &= ~AT91_MATRIX_USBPUCR_PUON;
                        at91_matrix_write(AT91_MATRIX_USBPUCR, usbpucr);
                }
                clk_off(udc);
        }
}

/* vbus is here!  turn everything on that's ready */
static int at91_vbus_session(struct usb_gadget *gadget, int is_active)
{
        struct at91_udc *udc = to_udc(gadget);
        unsigned long   flags;

        /* VDBG("vbus %s\n", is_active ? "on" : "off"); */
        spin_lock_irqsave(&udc->lock, flags);
        udc->vbus = (is_active != 0);
        if (udc->driver)
                pullup(udc, is_active);
        else
                pullup(udc, 0);
        spin_unlock_irqrestore(&udc->lock, flags);
        return 0;
}

static int at91_pullup(struct usb_gadget *gadget, int is_on)
{
        struct at91_udc *udc = to_udc(gadget);
        unsigned long   flags;

        spin_lock_irqsave(&udc->lock, flags);
        udc->enabled = is_on = !!is_on;
        pullup(udc, is_on);
        spin_unlock_irqrestore(&udc->lock, flags);
        return 0;
}

static int at91_set_selfpowered(struct usb_gadget *gadget, int is_on)
{
        struct at91_udc *udc = to_udc(gadget);
        unsigned long   flags;

        spin_lock_irqsave(&udc->lock, flags);
        udc->selfpowered = (is_on != 0);
        spin_unlock_irqrestore(&udc->lock, flags);
        return 0;
}

static int at91_start(struct usb_gadget *gadget,
                struct usb_gadget_driver *driver);
static int at91_stop(struct usb_gadget *gadget,
                struct usb_gadget_driver *driver);
static const struct usb_gadget_ops at91_udc_ops = {
        .get_frame              = at91_get_frame,
        .wakeup                 = at91_wakeup,
        .set_selfpowered        = at91_set_selfpowered,
        .vbus_session           = at91_vbus_session,
        .pullup                 = at91_pullup,
        .udc_start              = at91_start,
        .udc_stop               = at91_stop,

        /*
         * VBUS-powered devices may also also want to support bigger
         * power budgets after an appropriate SET_CONFIGURATION.

         */
        /* .vbus_power          = at91_vbus_power, */
};

/*-------------------------------------------------------------------------*/

static int handle_ep(struct at91_ep *ep)
{
        struct at91_request     *req;
        u32 __iomem             *creg = ep->creg;
        u32                     csr = __raw_readl(creg);

        if (!list_empty(&ep->queue))
                req = list_entry(ep->queue.next,
                        struct at91_request, queue);
        else
                req = NULL;

        if (ep->is_in) {
                if (csr & (AT91_UDP_STALLSENT | AT91_UDP_TXCOMP)) {
                        csr |= CLR_FX;
                        csr &= ~(SET_FX | AT91_UDP_STALLSENT | AT91_UDP_TXCOMP);
                        __raw_writel(csr, creg);
                }
                if (req)
                        return write_fifo(ep, req);

        } else {
                if (csr & AT91_UDP_STALLSENT) {
                        /* STALLSENT bit == ISOERR */
                        if (ep->is_iso && req)
                                req->req.status = -EILSEQ;
                        csr |= CLR_FX;
                        csr &= ~(SET_FX | AT91_UDP_STALLSENT);
                        __raw_writel(csr, creg);
                        csr = __raw_readl(creg);
                }
                if (req && (csr & RX_DATA_READY))
                        return read_fifo(ep, req);
        }
        return 0;
}

union setup {
        u8                      raw[8];
        struct usb_ctrlrequest  r;
};

static void handle_setup(struct at91_udc *udc, struct at91_ep *ep, u32 csr)
{
        u32 __iomem     *creg = ep->creg;
        u8 __iomem      *dreg = ep->creg + (AT91_UDP_FDR(0) - AT91_UDP_CSR(0));
        unsigned        rxcount, i = 0;
        u32             tmp;
        union setup     pkt;
        int             status = 0;

        /* read and ack SETUP; hard-fail for bogus packets */
        rxcount = (csr & AT91_UDP_RXBYTECNT) >> 16;
        if (likely(rxcount == 8)) {
                while (rxcount--)
                        pkt.raw[i++] = __raw_readb(dreg);
                if (pkt.r.bRequestType & USB_DIR_IN) {
                        csr |= AT91_UDP_DIR;
                        ep->is_in = 1;
                } else {
                        csr &= ~AT91_UDP_DIR;
                        ep->is_in = 0;
                }
        } else {
                /* REVISIT this happens sometimes under load; why?? */
                ERR("SETUP len %d, csr %08x\n", rxcount, csr);
                status = -EINVAL;
        }
        csr |= CLR_FX;
        csr &= ~(SET_FX | AT91_UDP_RXSETUP);
        __raw_writel(csr, creg);
        udc->wait_for_addr_ack = 0;
        udc->wait_for_config_ack = 0;
        ep->stopped = 0;
        if (unlikely(status != 0))
                goto stall;

#define w_index         le16_to_cpu(pkt.r.wIndex)
#define w_value         le16_to_cpu(pkt.r.wValue)
#define w_length        le16_to_cpu(pkt.r.wLength)

        VDBG("SETUP %02x.%02x v%04x i%04x l%04x\n",
                        pkt.r.bRequestType, pkt.r.bRequest,
                        w_value, w_index, w_length);

        /*
         * A few standard requests get handled here, ones that touch
         * hardware ... notably for device and endpoint features.
         */
        udc->req_pending = 1;
        csr = __raw_readl(creg);
        csr |= CLR_FX;
        csr &= ~SET_FX;
        switch ((pkt.r.bRequestType << 8) | pkt.r.bRequest) {

        case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                        | USB_REQ_SET_ADDRESS:
                __raw_writel(csr | AT91_UDP_TXPKTRDY, creg);
                udc->addr = w_value;
                udc->wait_for_addr_ack = 1;
                udc->req_pending = 0;
                /* FADDR is set later, when we ack host STATUS */
                return;

        case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                        | USB_REQ_SET_CONFIGURATION:
                tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT) & AT91_UDP_CONFG;
                if (pkt.r.wValue)
                        udc->wait_for_config_ack = (tmp == 0);
                else
                        udc->wait_for_config_ack = (tmp != 0);
                if (udc->wait_for_config_ack)
                        VDBG("wait for config\n");
                /* CONFG is toggled later, if gadget driver succeeds */
                break;

        /*
         * Hosts may set or clear remote wakeup status, and
         * devices may report they're VBUS powered.
         */
        case ((USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                        | USB_REQ_GET_STATUS:
                tmp = (udc->selfpowered << USB_DEVICE_SELF_POWERED);
                if (at91_udp_read(udc, AT91_UDP_GLB_STAT) & AT91_UDP_ESR)
                        tmp |= (1 << USB_DEVICE_REMOTE_WAKEUP);
                PACKET("get device status\n");
                __raw_writeb(tmp, dreg);
                __raw_writeb(0, dreg);
                goto write_in;
                /* then STATUS starts later, automatically */
        case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                        | USB_REQ_SET_FEATURE:
                if (w_value != USB_DEVICE_REMOTE_WAKEUP)
                        goto stall;
                tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
                tmp |= AT91_UDP_ESR;
                at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);
                goto succeed;
        case ((USB_TYPE_STANDARD|USB_RECIP_DEVICE) << 8)
                        | USB_REQ_CLEAR_FEATURE:
                if (w_value != USB_DEVICE_REMOTE_WAKEUP)
                        goto stall;
                tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
                tmp &= ~AT91_UDP_ESR;
                at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);
                goto succeed;

        /*
         * Interfaces have no feature settings; this is pretty useless.
         * we won't even insist the interface exists...
         */
        case ((USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_INTERFACE) << 8)
                        | USB_REQ_GET_STATUS:
                PACKET("get interface status\n");
                __raw_writeb(0, dreg);
                __raw_writeb(0, dreg);
                goto write_in;
                /* then STATUS starts later, automatically */
        case ((USB_TYPE_STANDARD|USB_RECIP_INTERFACE) << 8)
                        | USB_REQ_SET_FEATURE:
        case ((USB_TYPE_STANDARD|USB_RECIP_INTERFACE) << 8)
                        | USB_REQ_CLEAR_FEATURE:
                goto stall;

        /*
         * Hosts may clear bulk/intr endpoint halt after the gadget
         * driver sets it (not widely used); or set it (for testing)
         */
        case ((USB_DIR_IN|USB_TYPE_STANDARD|USB_RECIP_ENDPOINT) << 8)
                        | USB_REQ_GET_STATUS:
                tmp = w_index & USB_ENDPOINT_NUMBER_MASK;
                ep = &udc->ep[tmp];
                if (tmp >= NUM_ENDPOINTS || (tmp && !ep->ep.desc))
                        goto stall;

                if (tmp) {
                        if ((w_index & USB_DIR_IN)) {
                                if (!ep->is_in)
                                        goto stall;
                        } else if (ep->is_in)
                                goto stall;
                }
                PACKET("get %s status\n", ep->ep.name);
                if (__raw_readl(ep->creg) & AT91_UDP_FORCESTALL)
                        tmp = (1 << USB_ENDPOINT_HALT);
                else
                        tmp = 0;
                __raw_writeb(tmp, dreg);
                __raw_writeb(0, dreg);
                goto write_in;
                /* then STATUS starts later, automatically */
        case ((USB_TYPE_STANDARD|USB_RECIP_ENDPOINT) << 8)
                        | USB_REQ_SET_FEATURE:
                tmp = w_index & USB_ENDPOINT_NUMBER_MASK;
                ep = &udc->ep[tmp];
                if (w_value != USB_ENDPOINT_HALT || tmp >= NUM_ENDPOINTS)
                        goto stall;
                if (!ep->ep.desc || ep->is_iso)
                        goto stall;
                if ((w_index & USB_DIR_IN)) {
                        if (!ep->is_in)
                                goto stall;
                } else if (ep->is_in)
                        goto stall;

                tmp = __raw_readl(ep->creg);
                tmp &= ~SET_FX;
                tmp |= CLR_FX | AT91_UDP_FORCESTALL;
                __raw_writel(tmp, ep->creg);
                goto succeed;
        case ((USB_TYPE_STANDARD|USB_RECIP_ENDPOINT) << 8)
                        | USB_REQ_CLEAR_FEATURE:
                tmp = w_index & USB_ENDPOINT_NUMBER_MASK;
                ep = &udc->ep[tmp];
                if (w_value != USB_ENDPOINT_HALT || tmp >= NUM_ENDPOINTS)
                        goto stall;
                if (tmp == 0)
                        goto succeed;
                if (!ep->ep.desc || ep->is_iso)
                        goto stall;
                if ((w_index & USB_DIR_IN)) {
                        if (!ep->is_in)
                                goto stall;
                } else if (ep->is_in)
                        goto stall;

                at91_udp_write(udc, AT91_UDP_RST_EP, ep->int_mask);
                at91_udp_write(udc, AT91_UDP_RST_EP, 0);
                tmp = __raw_readl(ep->creg);
                tmp |= CLR_FX;
                tmp &= ~(SET_FX | AT91_UDP_FORCESTALL);
                __raw_writel(tmp, ep->creg);
                if (!list_empty(&ep->queue))
                        handle_ep(ep);
                goto succeed;
        }

#undef w_value
#undef w_index
#undef w_length

        /* pass request up to the gadget driver */
        if (udc->driver) {
                spin_unlock(&udc->lock);
                status = udc->driver->setup(&udc->gadget, &pkt.r);
                spin_lock(&udc->lock);
        }
        else
                status = -ENODEV;
        if (status < 0) {
stall:
                VDBG("req %02x.%02x protocol STALL; stat %d\n",
                                pkt.r.bRequestType, pkt.r.bRequest, status);
                csr |= AT91_UDP_FORCESTALL;
                __raw_writel(csr, creg);
                udc->req_pending = 0;
        }
        return;

succeed:
        /* immediate successful (IN) STATUS after zero length DATA */
        PACKET("ep0 in/status\n");
write_in:
        csr |= AT91_UDP_TXPKTRDY;
        __raw_writel(csr, creg);
        udc->req_pending = 0;
}

static void handle_ep0(struct at91_udc *udc)
{
        struct at91_ep          *ep0 = &udc->ep[0];
        u32 __iomem             *creg = ep0->creg;
        u32                     csr = __raw_readl(creg);
        struct at91_request     *req;

        if (unlikely(csr & AT91_UDP_STALLSENT)) {
                nuke(ep0, -EPROTO);
                udc->req_pending = 0;
                csr |= CLR_FX;
                csr &= ~(SET_FX | AT91_UDP_STALLSENT | AT91_UDP_FORCESTALL);
                __raw_writel(csr, creg);
                VDBG("ep0 stalled\n");
                csr = __raw_readl(creg);
        }
        if (csr & AT91_UDP_RXSETUP) {
                nuke(ep0, 0);
                udc->req_pending = 0;
                handle_setup(udc, ep0, csr);
                return;
        }

        if (list_empty(&ep0->queue))
                req = NULL;
        else
                req = list_entry(ep0->queue.next, struct at91_request, queue);

        /* host ACKed an IN packet that we sent */
        if (csr & AT91_UDP_TXCOMP) {
                csr |= CLR_FX;
                csr &= ~(SET_FX | AT91_UDP_TXCOMP);

                /* write more IN DATA? */
                if (req && ep0->is_in) {
                        if (handle_ep(ep0))
                                udc->req_pending = 0;

                /*
                 * Ack after:
                 *  - last IN DATA packet (including GET_STATUS)
                 *  - IN/STATUS for OUT DATA
                 *  - IN/STATUS for any zero-length DATA stage
                 * except for the IN DATA case, the host should send
                 * an OUT status later, which we'll ack.
                 */
                } else {
                        udc->req_pending = 0;
                        __raw_writel(csr, creg);

                        /*
                         * SET_ADDRESS takes effect only after the STATUS
                         * (to the original address) gets acked.
                         */
                        if (udc->wait_for_addr_ack) {
                                u32     tmp;

                                at91_udp_write(udc, AT91_UDP_FADDR,
                                                AT91_UDP_FEN | udc->addr);
                                tmp = at91_udp_read(udc, AT91_UDP_GLB_STAT);
                                tmp &= ~AT91_UDP_FADDEN;
                                if (udc->addr)
                                        tmp |= AT91_UDP_FADDEN;
                                at91_udp_write(udc, AT91_UDP_GLB_STAT, tmp);

                                udc->wait_for_addr_ack = 0;
                                VDBG("address %d\n", udc->addr);
                        }
                }
        }

        /* OUT packet arrived ... */
        else if (csr & AT91_UDP_RX_DATA_BK0) {
                csr |= CLR_FX;
                csr &= ~(SET_FX | AT91_UDP_RX_DATA_BK0);

                /* OUT DATA stage */
                if (!ep0->is_in) {
                        if (req) {
                                if (handle_ep(ep0)) {
                                        /* send IN/STATUS */
                                        PACKET("ep0 in/status\n");
                                        csr = __raw_readl(creg);
                                        csr &= ~SET_FX;
                                        csr |= CLR_FX | AT91_UDP_TXPKTRDY;
                                        __raw_writel(csr, creg);
                                        udc->req_pending = 0;
                                }
                        } else if (udc->req_pending) {
                                /*
                                 * AT91 hardware has a hard time with this
                                 * "deferred response" mode for control-OUT
                                 * transfers.  (For control-IN it's fine.)
                                 *
                                 * The normal solution leaves OUT data in the
                                 * fifo until the gadget driver is ready.
                                 * We couldn't do that here without disabling
                                 * the IRQ that tells about SETUP packets,
                                 * e.g. when the host gets impatient...
                                 *
                                 * Working around it by copying into a buffer
                                 * would almost be a non-deferred response,
                                 * except that it wouldn't permit reliable
                                 * stalling of the request.  Instead, demand
                                 * that gadget drivers not use this mode.
                                 */
                                DBG("no control-OUT deferred responses!\n");
                                __raw_writel(csr | AT91_UDP_FORCESTALL, creg);
                                udc->req_pending = 0;
                        }

                /* STATUS stage for control-IN; ack.  */
                } else {
                        PACKET("ep0 out/status ACK\n");
                        __raw_writel(csr, creg);

                        /* "early" status stage */
                        if (req)
                                done(ep0, req, 0);
                }
        }
}

static irqreturn_t at91_udc_irq (int irq, void *_udc)
{
        struct at91_udc         *udc = _udc;
        u32                     rescans = 5;
        int                     disable_clock = 0;
        unsigned long           flags;

        spin_lock_irqsave(&udc->lock, flags);

        if (!udc->clocked) {
                clk_on(udc);
                disable_clock = 1;
        }

        while (rescans--) {
                u32 status;

                status = at91_udp_read(udc, AT91_UDP_ISR)
                        & at91_udp_read(udc, AT91_UDP_IMR);
                if (!status)
                        break;

                /* USB reset irq:  not maskable */
                if (status & AT91_UDP_ENDBUSRES) {
                        at91_udp_write(udc, AT91_UDP_IDR, ~MINIMUS_INTERRUPTUS);
                        at91_udp_write(udc, AT91_UDP_IER, MINIMUS_INTERRUPTUS);
                        /* Atmel code clears this irq twice */
                        at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_ENDBUSRES);
                        at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_ENDBUSRES);
                        VDBG("end bus reset\n");
                        udc->addr = 0;
                        stop_activity(udc);

                        /* enable ep0 */
                        at91_udp_write(udc, AT91_UDP_CSR(0),
                                        AT91_UDP_EPEDS | AT91_UDP_EPTYPE_CTRL);
                        udc->gadget.speed = USB_SPEED_FULL;
                        udc->suspended = 0;
                        at91_udp_write(udc, AT91_UDP_IER, AT91_UDP_EP(0));

                        /*
                         * NOTE:  this driver keeps clocks off unless the
                         * USB host is present.  That saves power, but for
                         * boards that don't support VBUS detection, both
                         * clocks need to be active most of the time.
                         */

                /* host initiated suspend (3+ms bus idle) */
                } else if (status & AT91_UDP_RXSUSP) {
                        at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXSUSP);
                        at91_udp_write(udc, AT91_UDP_IER, AT91_UDP_RXRSM);
                        at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXSUSP);
                        /* VDBG("bus suspend\n"); */
                        if (udc->suspended)
                                continue;
                        udc->suspended = 1;

                        /*
                         * NOTE:  when suspending a VBUS-powered device, the
                         * gadget driver should switch into slow clock mode
                         * and then into standby to avoid drawing more than
                         * 500uA power (2500uA for some high-power configs).
                         */
                        if (udc->driver && udc->driver->suspend) {
                                spin_unlock(&udc->lock);
                                udc->driver->suspend(&udc->gadget);
                                spin_lock(&udc->lock);
                        }

                /* host initiated resume */
                } else if (status & AT91_UDP_RXRSM) {
                        at91_udp_write(udc, AT91_UDP_IDR, AT91_UDP_RXRSM);
                        at91_udp_write(udc, AT91_UDP_IER, AT91_UDP_RXSUSP);
                        at91_udp_write(udc, AT91_UDP_ICR, AT91_UDP_RXRSM);
                        /* VDBG("bus resume\n"); */
                        if (!udc->suspended)
                                continue;
                        udc->suspended = 0;

                        /*
                         * NOTE:  for a VBUS-powered device, the gadget driver
                         * would normally want to switch out of slow clock
                         * mode into normal mode.
                         */
                        if (udc->driver && udc->driver->resume) {
                                spin_unlock(&udc->lock);
                                udc->driver->resume(&udc->gadget);
                                spin_lock(&udc->lock);
                        }

                /* endpoint IRQs are cleared by handling them */
                } else {
                        int             i;
                        unsigned        mask = 1;
                        struct at91_ep  *ep = &udc->ep[1];

                        if (status & mask)
                                handle_ep0(udc);
                        for (i = 1; i < NUM_ENDPOINTS; i++) {
                                mask <<= 1;
                                if (status & mask)
                                        handle_ep(ep);
                                ep++;
                        }
                }
        }

        if (disable_clock)
                clk_off(udc);

        spin_unlock_irqrestore(&udc->lock, flags);

        return IRQ_HANDLED;
}

/*-------------------------------------------------------------------------*/

static void nop_release(struct device *dev)
{
        /* nothing to free */
}

static struct at91_udc controller = {
        .gadget = {
                .ops    = &at91_udc_ops,
                .ep0    = &controller.ep[0].ep,
                .name   = driver_name,
                .dev    = {
                        .init_name = "gadget",
                        .release = nop_release,
                }
        },
        .ep[0] = {
                .ep = {
                        .name   = ep0name,
                        .ops    = &at91_ep_ops,
                },
                .udc            = &controller,
                .maxpacket      = 8,
                .int_mask       = 1 << 0,
        },
        .ep[1] = {
                .ep = {
                        .name   = "ep1",
                        .ops    = &at91_ep_ops,
                },
                .udc            = &controller,
                .is_pingpong    = 1,
                .maxpacket      = 64,
                .int_mask       = 1 << 1,
        },
        .ep[2] = {
                .ep = {
                        .name   = "ep2",
                        .ops    = &at91_ep_ops,
                },
                .udc            = &controller,
                .is_pingpong    = 1,
                .maxpacket      = 64,
                .int_mask       = 1 << 2,
        },
        .ep[3] = {
                .ep = {
                        /* could actually do bulk too */
                        .name   = "ep3-int",
                        .ops    = &at91_ep_ops,
                },
                .udc            = &controller,
                .maxpacket      = 8,
                .int_mask       = 1 << 3,
        },
        .ep[4] = {
                .ep = {
                        .name   = "ep4",
                        .ops    = &at91_ep_ops,
                },
                .udc            = &controller,
                .is_pingpong    = 1,
                .maxpacket      = 256,
                .int_mask       = 1 << 4,
        },
        .ep[5] = {
                .ep = {
                        .name   = "ep5",
                        .ops    = &at91_ep_ops,
                },
                .udc            = &controller,
                .is_pingpong    = 1,
                .maxpacket      = 256,
                .int_mask       = 1 << 5,
        },
        /* ep6 and ep7 are also reserved (custom silicon might use them) */
};

static void at91_vbus_update(struct at91_udc *udc, unsigned value)
{
        value ^= udc->board.vbus_active_low;
        if (value != udc->vbus)
                at91_vbus_session(&udc->gadget, value);
}

static irqreturn_t at91_vbus_irq(int irq, void *_udc)
{
        struct at91_udc *udc = _udc;

        /* vbus needs at least brief debouncing */
        udelay(10);
        at91_vbus_update(udc, gpio_get_value(udc->board.vbus_pin));

        return IRQ_HANDLED;
}

static void at91_vbus_timer_work(struct work_struct *work)
{
        struct at91_udc *udc = container_of(work, struct at91_udc,
                                            vbus_timer_work);

        at91_vbus_update(udc, gpio_get_value_cansleep(udc->board.vbus_pin));

        if (!timer_pending(&udc->vbus_timer))
                mod_timer(&udc->vbus_timer, jiffies + VBUS_POLL_TIMEOUT);
}

static void at91_vbus_timer(unsigned long data)
{
        struct at91_udc *udc = (struct at91_udc *)data;

        /*
         * If we are polling vbus it is likely that the gpio is on an
         * bus such as i2c or spi which may sleep, so schedule some work
         * to read the vbus gpio
         */
        schedule_work(&udc->vbus_timer_work);
}

static int at91_start(struct usb_gadget *gadget,
                struct usb_gadget_driver *driver)
{
        struct at91_udc *udc;

        udc = container_of(gadget, struct at91_udc, gadget);
        udc->driver = driver;
        udc->gadget.dev.of_node = udc->pdev->dev.of_node;
        udc->enabled = 1;
        udc->selfpowered = 1;

        DBG("bound to %s\n", driver->driver.name);
        return 0;
}

static int at91_stop(struct usb_gadget *gadget,
                struct usb_gadget_driver *driver)
{
        struct at91_udc *udc;
        unsigned long   flags;

        udc = container_of(gadget, struct at91_udc, gadget);
        spin_lock_irqsave(&udc->lock, flags);
        udc->enabled = 0;
        at91_udp_write(udc, AT91_UDP_IDR, ~0);
        spin_unlock_irqrestore(&udc->lock, flags);

        udc->driver = NULL;

        DBG("unbound from %s\n", driver->driver.name);
        return 0;
}

/*-------------------------------------------------------------------------*/

static void at91udc_shutdown(struct platform_device *dev)
{
        struct at91_udc *udc = platform_get_drvdata(dev);
        unsigned long   flags;

        /* force disconnect on reboot */
        spin_lock_irqsave(&udc->lock, flags);
        pullup(platform_get_drvdata(dev), 0);
        spin_unlock_irqrestore(&udc->lock, flags);
}

static void at91udc_of_init(struct at91_udc *udc,
                                     struct device_node *np)
{
        struct at91_udc_data *board = &udc->board;
        u32 val;
        enum of_gpio_flags flags;

        if (of_property_read_u32(np, "atmel,vbus-polled", &val) == 0)
                board->vbus_polled = 1;

        board->vbus_pin = of_get_named_gpio_flags(np, "atmel,vbus-gpio", 0,
                                                  &flags);
        board->vbus_active_low = (flags & OF_GPIO_ACTIVE_LOW) ? 1 : 0;

        board->pullup_pin = of_get_named_gpio_flags(np, "atmel,pullup-gpio", 0,
                                                  &flags);

        board->pullup_active_low = (flags & OF_GPIO_ACTIVE_LOW) ? 1 : 0;
}

static int at91udc_probe(struct platform_device *pdev)
{
        struct device   *dev = &pdev->dev;
        struct at91_udc *udc;
        int             retval;
        struct resource *res;

        if (!dev_get_platdata(dev) && !pdev->dev.of_node) {
                /* small (so we copy it) but critical! */
                DBG("missing platform_data\n");
                return -ENODEV;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENXIO;

        if (!request_mem_region(res->start, resource_size(res), driver_name)) {
                DBG("someone's using UDC memory\n");
                return -EBUSY;
        }

        /* init software state */
        udc = &controller;
        udc->gadget.dev.parent = dev;
        if (IS_ENABLED(CONFIG_OF) && pdev->dev.of_node)
                at91udc_of_init(udc, pdev->dev.of_node);
        else
                memcpy(&udc->board, dev_get_platdata(dev),
                       sizeof(struct at91_udc_data));
        udc->pdev = pdev;
        udc->enabled = 0;
        spin_lock_init(&udc->lock);

        /* rm9200 needs manual D+ pullup; off by default */
        if (cpu_is_at91rm9200()) {
                if (!gpio_is_valid(udc->board.pullup_pin)) {
                        DBG("no D+ pullup?\n");
                        retval = -ENODEV;
                        goto fail0;
                }
                retval = gpio_request(udc->board.pullup_pin, "udc_pullup");
                if (retval) {
                        DBG("D+ pullup is busy\n");
                        goto fail0;
                }
                gpio_direction_output(udc->board.pullup_pin,
                                udc->board.pullup_active_low);
        }

        /* newer chips have more FIFO memory than rm9200 */
        if (cpu_is_at91sam9260() || cpu_is_at91sam9g20()) {
                udc->ep[0].maxpacket = 64;
                udc->ep[3].maxpacket = 64;
                udc->ep[4].maxpacket = 512;
                udc->ep[5].maxpacket = 512;
        } else if (cpu_is_at91sam9261() || cpu_is_at91sam9g10()) {
                udc->ep[3].maxpacket = 64;
        } else if (cpu_is_at91sam9263()) {
                udc->ep[0].maxpacket = 64;
                udc->ep[3].maxpacket = 64;
        }

        udc->udp_baseaddr = ioremap(res->start, resource_size(res));
        if (!udc->udp_baseaddr) {
                retval = -ENOMEM;
                goto fail0a;
        }

        udc_reinit(udc);

        /* get interface and function clocks */
        udc->iclk = clk_get(dev, "udc_clk");
        udc->fclk = clk_get(dev, "udpck");
        if (IS_ENABLED(CONFIG_COMMON_CLK))
                udc->uclk = clk_get(dev, "usb_clk");
        if (IS_ERR(udc->iclk) || IS_ERR(udc->fclk) ||
            (IS_ENABLED(CONFIG_COMMON_CLK) && IS_ERR(udc->uclk))) {
                DBG("clocks missing\n");
                retval = -ENODEV;
                goto fail1;
        }

        /* don't do anything until we have both gadget driver and VBUS */
        retval = clk_prepare_enable(udc->iclk);
        if (retval)
                goto fail1;
        at91_udp_write(udc, AT91_UDP_TXVC, AT91_UDP_TXVC_TXVDIS);
        at91_udp_write(udc, AT91_UDP_IDR, 0xffffffff);
        /* Clear all pending interrupts - UDP may be used by bootloader. */
        at91_udp_write(udc, AT91_UDP_ICR, 0xffffffff);
        clk_disable_unprepare(udc->iclk);

        /* request UDC and maybe VBUS irqs */
        udc->udp_irq = platform_get_irq(pdev, 0);
        retval = request_irq(udc->udp_irq, at91_udc_irq,
                        0, driver_name, udc);
        if (retval < 0) {
                DBG("request irq %d failed\n", udc->udp_irq);
                goto fail1;
        }
        if (gpio_is_valid(udc->board.vbus_pin)) {
                retval = gpio_request(udc->board.vbus_pin, "udc_vbus");
                if (retval < 0) {
                        DBG("request vbus pin failed\n");
                        goto fail2;
                }
                gpio_direction_input(udc->board.vbus_pin);

                /*
                 * Get the initial state of VBUS - we cannot expect
                 * a pending interrupt.
                 */
                udc->vbus = gpio_get_value_cansleep(udc->board.vbus_pin) ^
                        udc->board.vbus_active_low;

                if (udc->board.vbus_polled) {
                        INIT_WORK(&udc->vbus_timer_work, at91_vbus_timer_work);
                        setup_timer(&udc->vbus_timer, at91_vbus_timer,
                                    (unsigned long)udc);
                        mod_timer(&udc->vbus_timer,
                                  jiffies + VBUS_POLL_TIMEOUT);
                } else {
                        if (request_irq(gpio_to_irq(udc->board.vbus_pin),
                                        at91_vbus_irq, 0, driver_name, udc)) {
                                DBG("request vbus irq %d failed\n",
                                    udc->board.vbus_pin);
                                retval = -EBUSY;
                                goto fail3;
                        }
                }
        } else {
                DBG("no VBUS detection, assuming always-on\n");
                udc->vbus = 1;
        }
        retval = usb_add_gadget_udc(dev, &udc->gadget);
        if (retval)
                goto fail4;
        dev_set_drvdata(dev, udc);
        device_init_wakeup(dev, 1);
        create_debug_file(udc);

        INFO("%s version %s\n", driver_name, DRIVER_VERSION);
        return 0;
fail4:
        if (gpio_is_valid(udc->board.vbus_pin) && !udc->board.vbus_polled)
                free_irq(gpio_to_irq(udc->board.vbus_pin), udc);
fail3:
        if (gpio_is_valid(udc->board.vbus_pin))
                gpio_free(udc->board.vbus_pin);
fail2:
        free_irq(udc->udp_irq, udc);
fail1:
        if (IS_ENABLED(CONFIG_COMMON_CLK) && !IS_ERR(udc->uclk))
                clk_put(udc->uclk);
        if (!IS_ERR(udc->fclk))
                clk_put(udc->fclk);
        if (!IS_ERR(udc->iclk))
                clk_put(udc->iclk);
        iounmap(udc->udp_baseaddr);
fail0a:
        if (cpu_is_at91rm9200())
                gpio_free(udc->board.pullup_pin);
fail0:
        release_mem_region(res->start, resource_size(res));
        DBG("%s probe failed, %d\n", driver_name, retval);
        return retval;
}

static int __exit at91udc_remove(struct platform_device *pdev)
{
        struct at91_udc *udc = platform_get_drvdata(pdev);
        struct resource *res;
        unsigned long   flags;

        DBG("remove\n");

        usb_del_gadget_udc(&udc->gadget);
        if (udc->driver)
                return -EBUSY;

        spin_lock_irqsave(&udc->lock, flags);
        pullup(udc, 0);
        spin_unlock_irqrestore(&udc->lock, flags);

        device_init_wakeup(&pdev->dev, 0);
        remove_debug_file(udc);
        if (gpio_is_valid(udc->board.vbus_pin)) {
                free_irq(gpio_to_irq(udc->board.vbus_pin), udc);
                gpio_free(udc->board.vbus_pin);
        }
        free_irq(udc->udp_irq, udc);
        iounmap(udc->udp_baseaddr);

        if (cpu_is_at91rm9200())
                gpio_free(udc->board.pullup_pin);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        release_mem_region(res->start, resource_size(res));

        clk_put(udc->iclk);
        clk_put(udc->fclk);
        if (IS_ENABLED(CONFIG_COMMON_CLK))
                clk_put(udc->uclk);

        return 0;
}

#ifdef CONFIG_PM
static int at91udc_suspend(struct platform_device *pdev, pm_message_t mesg)
{
        struct at91_udc *udc = platform_get_drvdata(pdev);
        int             wake = udc->driver && device_may_wakeup(&pdev->dev);
        unsigned long   flags;

        /* Unless we can act normally to the host (letting it wake us up
         * whenever it has work for us) force disconnect.  Wakeup requires
         * PLLB for USB events (signaling for reset, wakeup, or incoming
         * tokens) and VBUS irqs (on systems which support them).
         */
        if ((!udc->suspended && udc->addr)
                        || !wake
                        || at91_suspend_entering_slow_clock()) {
                spin_lock_irqsave(&udc->lock, flags);
                pullup(udc, 0);
                wake = 0;
                spin_unlock_irqrestore(&udc->lock, flags);
        } else
                enable_irq_wake(udc->udp_irq);

        udc->active_suspend = wake;
        if (gpio_is_valid(udc->board.vbus_pin) && !udc->board.vbus_polled && wake)
                enable_irq_wake(udc->board.vbus_pin);
        return 0;
}

static int at91udc_resume(struct platform_device *pdev)
{
        struct at91_udc *udc = platform_get_drvdata(pdev);
        unsigned long   flags;

        if (gpio_is_valid(udc->board.vbus_pin) && !udc->board.vbus_polled &&
            udc->active_suspend)
                disable_irq_wake(udc->board.vbus_pin);

        /* maybe reconnect to host; if so, clocks on */
        if (udc->active_suspend)
                disable_irq_wake(udc->udp_irq);
        else {
                spin_lock_irqsave(&udc->lock, flags);
                pullup(udc, 1);
                spin_unlock_irqrestore(&udc->lock, flags);
        }
        return 0;
}
#else
#define at91udc_suspend NULL
#define at91udc_resume  NULL
#endif

#if defined(CONFIG_OF)
static const struct of_device_id at91_udc_dt_ids[] = {
        { .compatible = "atmel,at91rm9200-udc" },
        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, at91_udc_dt_ids);
#endif

static struct platform_driver at91_udc_driver = {
        .remove         = __exit_p(at91udc_remove),
        .shutdown       = at91udc_shutdown,
        .suspend        = at91udc_suspend,
        .resume         = at91udc_resume,
        .driver         = {
                .name   = (char *) driver_name,
                .owner  = THIS_MODULE,
                .of_match_table = of_match_ptr(at91_udc_dt_ids),
        },
};

module_platform_driver_probe(at91_udc_driver, at91udc_probe);

MODULE_DESCRIPTION("AT91 udc driver");
MODULE_AUTHOR("Thomas Rathbone, David Brownell");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:at91_udc");