// SPDX-License-Identifier: GPL-2.0+
/*
 * aspeed-vhub -- Driver for Aspeed SoC "vHub" USB gadget
 *
 * epn.c - Generic endpoints management
 *
 * Copyright 2017 IBM Corporation
 *
 * 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.
 */

#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/gadget.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/regmap.h>
#include <linux/dma-mapping.h>

#include "vhub.h"

#define EXTRA_CHECKS

#ifdef EXTRA_CHECKS
#define CHECK(ep, expr, fmt...)                                 \
        do {                                                    \
                if (!(expr)) EPDBG(ep, "CHECK:" fmt);           \
        } while(0)
#else
#define CHECK(ep, expr, fmt...) do { } while(0)
#endif

static void ast_vhub_epn_kick(struct ast_vhub_ep *ep, struct ast_vhub_req *req)
{
        unsigned int act = req->req.actual;
        unsigned int len = req->req.length;
        unsigned int chunk;

        /* There should be no DMA ongoing */
        WARN_ON(req->active);

        /* Calculate next chunk size */
        chunk = len - act;
        if (chunk > ep->ep.maxpacket)
                chunk = ep->ep.maxpacket;
        else if ((chunk < ep->ep.maxpacket) || !req->req.zero)
                req->last_desc = 1;

        EPVDBG(ep, "kick req %p act=%d/%d chunk=%d last=%d\n",
               req, act, len, chunk, req->last_desc);

        /* If DMA unavailable, using staging EP buffer */
        if (!req->req.dma) {

                /* For IN transfers, copy data over first */
                if (ep->epn.is_in) {
                        memcpy(ep->buf, req->req.buf + act, chunk);
                        vhub_dma_workaround(ep->buf);
                }
                writel(ep->buf_dma, ep->epn.regs + AST_VHUB_EP_DESC_BASE);
        } else {
                if (ep->epn.is_in)
                        vhub_dma_workaround(req->req.buf);
                writel(req->req.dma + act, ep->epn.regs + AST_VHUB_EP_DESC_BASE);
        }

        /* Start DMA */
        req->active = true;
        writel(VHUB_EP_DMA_SET_TX_SIZE(chunk),
               ep->epn.regs + AST_VHUB_EP_DESC_STATUS);
        writel(VHUB_EP_DMA_SET_TX_SIZE(chunk) | VHUB_EP_DMA_SINGLE_KICK,
               ep->epn.regs + AST_VHUB_EP_DESC_STATUS);
}

static void ast_vhub_epn_handle_ack(struct ast_vhub_ep *ep)
{
        struct ast_vhub_req *req;
        unsigned int len;
        u32 stat;

        /* Read EP status */
        stat = readl(ep->epn.regs + AST_VHUB_EP_DESC_STATUS);

        /* Grab current request if any */
        req = list_first_entry_or_null(&ep->queue, struct ast_vhub_req, queue);

        EPVDBG(ep, "ACK status=%08x is_in=%d, req=%p (active=%d)\n",
               stat, ep->epn.is_in, req, req ? req->active : 0);

        /* In absence of a request, bail out, must have been dequeued */
        if (!req)
                return;

        /*
         * Request not active, move on to processing queue, active request
         * was probably dequeued
         */
        if (!req->active)
                goto next_chunk;

        /* Check if HW has moved on */
        if (VHUB_EP_DMA_RPTR(stat) != 0) {
                EPDBG(ep, "DMA read pointer not 0 !\n");
                return;
        }

        /* No current DMA ongoing */
        req->active = false;

        /* Grab length out of HW */
        len = VHUB_EP_DMA_TX_SIZE(stat);

        /* If not using DMA, copy data out if needed */
        if (!req->req.dma && !ep->epn.is_in && len)
                memcpy(req->req.buf + req->req.actual, ep->buf, len);

        /* Adjust size */
        req->req.actual += len;

        /* Check for short packet */
        if (len < ep->ep.maxpacket)
                req->last_desc = 1;

        /* That's it ? complete the request and pick a new one */
        if (req->last_desc >= 0) {
                ast_vhub_done(ep, req, 0);
                req = list_first_entry_or_null(&ep->queue, struct ast_vhub_req,
                                               queue);

                /*
                 * Due to lock dropping inside "done" the next request could
                 * already be active, so check for that and bail if needed.
                 */
                if (!req || req->active)
                        return;
        }

 next_chunk:
        ast_vhub_epn_kick(ep, req);
}

static inline unsigned int ast_vhub_count_free_descs(struct ast_vhub_ep *ep)
{
        /*
         * d_next == d_last means descriptor list empty to HW,
         * thus we can only have AST_VHUB_DESCS_COUNT-1 descriptors
         * in the list
         */
        return (ep->epn.d_last + AST_VHUB_DESCS_COUNT - ep->epn.d_next - 1) &
                (AST_VHUB_DESCS_COUNT - 1);
}

static void ast_vhub_epn_kick_desc(struct ast_vhub_ep *ep,
                                   struct ast_vhub_req *req)
{
        struct ast_vhub_desc *desc = NULL;
        unsigned int act = req->act_count;
        unsigned int len = req->req.length;
        unsigned int chunk;

        /* Mark request active if not already */
        req->active = true;

        /* If the request was already completely written, do nothing */
        if (req->last_desc >= 0)
                return;

        EPVDBG(ep, "kick act=%d/%d chunk_max=%d free_descs=%d\n",
               act, len, ep->epn.chunk_max, ast_vhub_count_free_descs(ep));

        /* While we can create descriptors */
        while (ast_vhub_count_free_descs(ep) && req->last_desc < 0) {
                unsigned int d_num;

                /* Grab next free descriptor */
                d_num = ep->epn.d_next;
                desc = &ep->epn.descs[d_num];
                ep->epn.d_next = (d_num + 1) & (AST_VHUB_DESCS_COUNT - 1);

                /* Calculate next chunk size */
                chunk = len - act;
                if (chunk <= ep->epn.chunk_max) {
                        /*
                         * Is this the last packet ? Because of having up to 8
                         * packets in a descriptor we can't just compare "chunk"
                         * with ep.maxpacket. We have to see if it's a multiple
                         * of it to know if we have to send a zero packet.
                         * Sadly that involves a modulo which is a bit expensive
                         * but probably still better than not doing it.
                         */
                        if (!chunk || !req->req.zero || (chunk % ep->ep.maxpacket) != 0)
                                req->last_desc = d_num;
                } else {
                        chunk = ep->epn.chunk_max;
                }

                EPVDBG(ep, " chunk: act=%d/%d chunk=%d last=%d desc=%d free=%d\n",
                       act, len, chunk, req->last_desc, d_num,
                       ast_vhub_count_free_descs(ep));

                /* Populate descriptor */
                desc->w0 = cpu_to_le32(req->req.dma + act);

                /* Interrupt if end of request or no more descriptors */

                /*
                 * TODO: Be smarter about it, if we don't have enough
                 * descriptors request an interrupt before queue empty
                 * or so in order to be able to populate more before
                 * the HW runs out. This isn't a problem at the moment
                 * as we use 256 descriptors and only put at most one
                 * request in the ring.
                 */
                desc->w1 = cpu_to_le32(VHUB_DSC1_IN_SET_LEN(chunk));
                if (req->last_desc >= 0 || !ast_vhub_count_free_descs(ep))
                        desc->w1 |= cpu_to_le32(VHUB_DSC1_IN_INTERRUPT);

                /* Account packet */
                req->act_count = act = act + chunk;
        }

        if (likely(desc))
                vhub_dma_workaround(desc);

        /* Tell HW about new descriptors */
        writel(VHUB_EP_DMA_SET_CPU_WPTR(ep->epn.d_next),
               ep->epn.regs + AST_VHUB_EP_DESC_STATUS);

        EPVDBG(ep, "HW kicked, d_next=%d dstat=%08x\n",
               ep->epn.d_next, readl(ep->epn.regs + AST_VHUB_EP_DESC_STATUS));
}

static void ast_vhub_epn_handle_ack_desc(struct ast_vhub_ep *ep)
{
        struct ast_vhub_req *req;
        unsigned int len, d_last;
        u32 stat, stat1;

        /* Read EP status, workaround HW race */
        do {
                stat = readl(ep->epn.regs + AST_VHUB_EP_DESC_STATUS);
                stat1 = readl(ep->epn.regs + AST_VHUB_EP_DESC_STATUS);
        } while(stat != stat1);

        /* Extract RPTR */
        d_last = VHUB_EP_DMA_RPTR(stat);

        /* Grab current request if any */
        req = list_first_entry_or_null(&ep->queue, struct ast_vhub_req, queue);

        EPVDBG(ep, "ACK status=%08x is_in=%d ep->d_last=%d..%d\n",
               stat, ep->epn.is_in, ep->epn.d_last, d_last);

        /* Check all completed descriptors */
        while (ep->epn.d_last != d_last) {
                struct ast_vhub_desc *desc;
                unsigned int d_num;
                bool is_last_desc;

                /* Grab next completed descriptor */
                d_num = ep->epn.d_last;
                desc = &ep->epn.descs[d_num];
                ep->epn.d_last = (d_num + 1) & (AST_VHUB_DESCS_COUNT - 1);

                /* Grab len out of descriptor */
                len = VHUB_DSC1_IN_LEN(le32_to_cpu(desc->w1));

                EPVDBG(ep, " desc %d len=%d req=%p (act=%d)\n",
                       d_num, len, req, req ? req->active : 0);

                /* If no active request pending, move on */
                if (!req || !req->active)
                        continue;

                /* Adjust size */
                req->req.actual += len;

                /* Is that the last chunk ? */
                is_last_desc = req->last_desc == d_num;
                CHECK(ep, is_last_desc == (len < ep->ep.maxpacket ||
                                           (req->req.actual >= req->req.length &&
                                            !req->req.zero)),
                      "Last packet discrepancy: last_desc=%d len=%d r.act=%d "
                      "r.len=%d r.zero=%d mp=%d\n",
                      is_last_desc, len, req->req.actual, req->req.length,
                      req->req.zero, ep->ep.maxpacket);

                if (is_last_desc) {
                        /*
                         * Because we can only have one request at a time
                         * in our descriptor list in this implementation,
                         * d_last and ep->d_last should now be equal
                         */
                        CHECK(ep, d_last == ep->epn.d_last,
                              "DMA read ptr mismatch %d vs %d\n",
                              d_last, ep->epn.d_last);

                        /* Note: done will drop and re-acquire the lock */
                        ast_vhub_done(ep, req, 0);
                        req = list_first_entry_or_null(&ep->queue,
                                                       struct ast_vhub_req,
                                                       queue);
                        break;
                }
        }

        /* More work ? */
        if (req)
                ast_vhub_epn_kick_desc(ep, req);
}

void ast_vhub_epn_ack_irq(struct ast_vhub_ep *ep)
{
        if (ep->epn.desc_mode)
                ast_vhub_epn_handle_ack_desc(ep);
        else
                ast_vhub_epn_handle_ack(ep);
}

static int ast_vhub_epn_queue(struct usb_ep* u_ep, struct usb_request *u_req,
                              gfp_t gfp_flags)
{
        struct ast_vhub_req *req = to_ast_req(u_req);
        struct ast_vhub_ep *ep = to_ast_ep(u_ep);
        struct ast_vhub *vhub = ep->vhub;
        unsigned long flags;
        bool empty;
        int rc;

        /* Paranoid checks */
        if (!u_req || !u_req->complete || !u_req->buf) {
                dev_warn(&vhub->pdev->dev, "Bogus EPn request ! u_req=%p\n", u_req);
                if (u_req) {
                        dev_warn(&vhub->pdev->dev, "complete=%p internal=%d\n",
                                 u_req->complete, req->internal);
                }
                return -EINVAL;
        }

        /* Endpoint enabled ? */
        if (!ep->epn.enabled || !u_ep->desc || !ep->dev || !ep->d_idx ||
            !ep->dev->enabled || ep->dev->suspended) {
                EPDBG(ep, "Enqueuing request on wrong or disabled EP\n");
                return -ESHUTDOWN;
        }

        /* Map request for DMA if possible. For now, the rule for DMA is
         * that:
         *
         *  * For single stage mode (no descriptors):
         *
         *   - The buffer is aligned to a 8 bytes boundary (HW requirement)
         *   - For a OUT endpoint, the request size is a multiple of the EP
         *     packet size (otherwise the controller will DMA past the end
         *     of the buffer if the host is sending a too long packet).
         *
         *  * For descriptor mode (tx only for now), always.
         *
         * We could relax the latter by making the decision to use the bounce
         * buffer based on the size of a given *segment* of the request rather
         * than the whole request.
         */
        if (ep->epn.desc_mode ||
            ((((unsigned long)u_req->buf & 7) == 0) &&
             (ep->epn.is_in || !(u_req->length & (u_ep->maxpacket - 1))))) {
                rc = usb_gadget_map_request(&ep->dev->gadget, u_req,
                                            ep->epn.is_in);
                if (rc) {
                        dev_warn(&vhub->pdev->dev,
                                 "Request mapping failure %d\n", rc);
                        return rc;
                }
        } else
                u_req->dma = 0;

        EPVDBG(ep, "enqueue req @%p\n", req);
        EPVDBG(ep, " l=%d dma=0x%x zero=%d noshort=%d noirq=%d is_in=%d\n",
               u_req->length, (u32)u_req->dma, u_req->zero,
               u_req->short_not_ok, u_req->no_interrupt,
               ep->epn.is_in);

        /* Initialize request progress fields */
        u_req->status = -EINPROGRESS;
        u_req->actual = 0;
        req->act_count = 0;
        req->active = false;
        req->last_desc = -1;
        spin_lock_irqsave(&vhub->lock, flags);
        empty = list_empty(&ep->queue);

        /* Add request to list and kick processing if empty */
        list_add_tail(&req->queue, &ep->queue);
        if (empty) {
                if (ep->epn.desc_mode)
                        ast_vhub_epn_kick_desc(ep, req);
                else
                        ast_vhub_epn_kick(ep, req);
        }
        spin_unlock_irqrestore(&vhub->lock, flags);

        return 0;
}

static void ast_vhub_stop_active_req(struct ast_vhub_ep *ep,
                                     bool restart_ep)
{
        u32 state, reg, loops;

        /* Stop DMA activity */
        writel(0, ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);

        /* Wait for it to complete */
        for (loops = 0; loops < 1000; loops++) {
                state = readl(ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);
                state = VHUB_EP_DMA_PROC_STATUS(state);
                if (state == EP_DMA_PROC_RX_IDLE ||
                    state == EP_DMA_PROC_TX_IDLE)
                        break;
                udelay(1);
        }
        if (loops >= 1000)
                dev_warn(&ep->vhub->pdev->dev, "Timeout waiting for DMA\n");

        /* If we don't have to restart the endpoint, that's it */
        if (!restart_ep)
                return;

        /* Restart the endpoint */
        if (ep->epn.desc_mode) {
                /*
                 * Take out descriptors by resetting the DMA read
                 * pointer to be equal to the CPU write pointer.
                 *
                 * Note: If we ever support creating descriptors for
                 * requests that aren't the head of the queue, we
                 * may have to do something more complex here,
                 * especially if the request being taken out is
                 * not the current head descriptors.
                 */
                reg = VHUB_EP_DMA_SET_RPTR(ep->epn.d_next) |
                        VHUB_EP_DMA_SET_CPU_WPTR(ep->epn.d_next);
                writel(reg, ep->epn.regs + AST_VHUB_EP_DESC_STATUS);

                /* Then turn it back on */
                writel(ep->epn.dma_conf,
                       ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);
        } else {
                /* Single mode: just turn it back on */
                writel(ep->epn.dma_conf,
                       ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);
        }
}

static int ast_vhub_epn_dequeue(struct usb_ep* u_ep, struct usb_request *u_req)
{
        struct ast_vhub_ep *ep = to_ast_ep(u_ep);
        struct ast_vhub *vhub = ep->vhub;
        struct ast_vhub_req *req;
        unsigned long flags;
        int rc = -EINVAL;

        spin_lock_irqsave(&vhub->lock, flags);

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

        if (&req->req == u_req) {
                EPVDBG(ep, "dequeue req @%p active=%d\n",
                       req, req->active);
                if (req->active)
                        ast_vhub_stop_active_req(ep, true);
                ast_vhub_done(ep, req, -ECONNRESET);
                rc = 0;
        }

        spin_unlock_irqrestore(&vhub->lock, flags);
        return rc;
}

void ast_vhub_update_epn_stall(struct ast_vhub_ep *ep)
{
        u32 reg;

        if (WARN_ON(ep->d_idx == 0))
                return;
        reg = readl(ep->epn.regs + AST_VHUB_EP_CONFIG);
        if (ep->epn.stalled || ep->epn.wedged)
                reg |= VHUB_EP_CFG_STALL_CTRL;
        else
                reg &= ~VHUB_EP_CFG_STALL_CTRL;
        writel(reg, ep->epn.regs + AST_VHUB_EP_CONFIG);

        if (!ep->epn.stalled && !ep->epn.wedged)
                writel(VHUB_EP_TOGGLE_SET_EPNUM(ep->epn.g_idx),
                       ep->vhub->regs + AST_VHUB_EP_TOGGLE);
}

static int ast_vhub_set_halt_and_wedge(struct usb_ep* u_ep, bool halt,
                                      bool wedge)
{
        struct ast_vhub_ep *ep = to_ast_ep(u_ep);
        struct ast_vhub *vhub = ep->vhub;
        unsigned long flags;

        EPDBG(ep, "Set halt (%d) & wedge (%d)\n", halt, wedge);

        if (!u_ep || !u_ep->desc)
                return -EINVAL;
        if (ep->d_idx == 0)
                return 0;
        if (ep->epn.is_iso)
                return -EOPNOTSUPP;

        spin_lock_irqsave(&vhub->lock, flags);

        /* Fail with still-busy IN endpoints */
        if (halt && ep->epn.is_in && !list_empty(&ep->queue)) {
                spin_unlock_irqrestore(&vhub->lock, flags);
                return -EAGAIN;
        }
        ep->epn.stalled = halt;
        ep->epn.wedged = wedge;
        ast_vhub_update_epn_stall(ep);

        spin_unlock_irqrestore(&vhub->lock, flags);

        return 0;
}

static int ast_vhub_epn_set_halt(struct usb_ep *u_ep, int value)
{
        return ast_vhub_set_halt_and_wedge(u_ep, value != 0, false);
}

static int ast_vhub_epn_set_wedge(struct usb_ep *u_ep)
{
        return ast_vhub_set_halt_and_wedge(u_ep, true, true);
}

static int ast_vhub_epn_disable(struct usb_ep* u_ep)
{
        struct ast_vhub_ep *ep = to_ast_ep(u_ep);
        struct ast_vhub *vhub = ep->vhub;
        unsigned long flags;
        u32 imask, ep_ier;

        EPDBG(ep, "Disabling !\n");

        spin_lock_irqsave(&vhub->lock, flags);

        ep->epn.enabled = false;

        /* Stop active DMA if any */
        ast_vhub_stop_active_req(ep, false);

        /* Disable endpoint */
        writel(0, ep->epn.regs + AST_VHUB_EP_CONFIG);

        /* Disable ACK interrupt */
        imask = VHUB_EP_IRQ(ep->epn.g_idx);
        ep_ier = readl(vhub->regs + AST_VHUB_EP_ACK_IER);
        ep_ier &= ~imask;
        writel(ep_ier, vhub->regs + AST_VHUB_EP_ACK_IER);
        writel(imask, vhub->regs + AST_VHUB_EP_ACK_ISR);

        /* Nuke all pending requests */
        ast_vhub_nuke(ep, -ESHUTDOWN);

        /* No more descriptor associated with request */
        ep->ep.desc = NULL;

        spin_unlock_irqrestore(&vhub->lock, flags);

        return 0;
}

static int ast_vhub_epn_enable(struct usb_ep* u_ep,
                               const struct usb_endpoint_descriptor *desc)
{
        struct ast_vhub_ep *ep = to_ast_ep(u_ep);
        struct ast_vhub_dev *dev;
        struct ast_vhub *vhub;
        u16 maxpacket, type;
        unsigned long flags;
        u32 ep_conf, ep_ier, imask;

        /* Check arguments */
        if (!u_ep || !desc)
                return -EINVAL;

        maxpacket = usb_endpoint_maxp(desc);
        if (!ep->d_idx || !ep->dev ||
            desc->bDescriptorType != USB_DT_ENDPOINT ||
            maxpacket == 0 || maxpacket > ep->ep.maxpacket) {
                EPDBG(ep, "Invalid EP enable,d_idx=%d,dev=%p,type=%d,mp=%d/%d\n",
                      ep->d_idx, ep->dev, desc->bDescriptorType,
                      maxpacket, ep->ep.maxpacket);
                return -EINVAL;
        }
        if (ep->d_idx != usb_endpoint_num(desc)) {
                EPDBG(ep, "EP number mismatch !\n");
                return -EINVAL;
        }

        if (ep->epn.enabled) {
                EPDBG(ep, "Already enabled\n");
                return -EBUSY;
        }
        dev = ep->dev;
        vhub = ep->vhub;

        /* Check device state */
        if (!dev->driver) {
                EPDBG(ep, "Bogus device state: driver=%p speed=%d\n",
                       dev->driver, dev->gadget.speed);
                return -ESHUTDOWN;
        }

        /* Grab some info from the descriptor */
        ep->epn.is_in = usb_endpoint_dir_in(desc);
        ep->ep.maxpacket = maxpacket;
        type = usb_endpoint_type(desc);
        ep->epn.d_next = ep->epn.d_last = 0;
        ep->epn.is_iso = false;
        ep->epn.stalled = false;
        ep->epn.wedged = false;

        EPDBG(ep, "Enabling [%s] %s num %d maxpacket=%d\n",
              ep->epn.is_in ? "in" : "out", usb_ep_type_string(type),
              usb_endpoint_num(desc), maxpacket);

        /* Can we use DMA descriptor mode ? */
        ep->epn.desc_mode = ep->epn.descs && ep->epn.is_in;
        if (ep->epn.desc_mode)
                memset(ep->epn.descs, 0, 8 * AST_VHUB_DESCS_COUNT);

        /*
         * Large send function can send up to 8 packets from
         * one descriptor with a limit of 4095 bytes.
         */
        ep->epn.chunk_max = ep->ep.maxpacket;
        if (ep->epn.is_in) {
                ep->epn.chunk_max <<= 3;
                while (ep->epn.chunk_max > 4095)
                        ep->epn.chunk_max -= ep->ep.maxpacket;
        }

        switch(type) {
        case USB_ENDPOINT_XFER_CONTROL:
                EPDBG(ep, "Only one control endpoint\n");
                return -EINVAL;
        case USB_ENDPOINT_XFER_INT:
                ep_conf = VHUB_EP_CFG_SET_TYPE(EP_TYPE_INT);
                break;
        case USB_ENDPOINT_XFER_BULK:
                ep_conf = VHUB_EP_CFG_SET_TYPE(EP_TYPE_BULK);
                break;
        case USB_ENDPOINT_XFER_ISOC:
                ep_conf = VHUB_EP_CFG_SET_TYPE(EP_TYPE_ISO);
                ep->epn.is_iso = true;
                break;
        default:
                return -EINVAL;
        }

        /* Encode the rest of the EP config register */
        if (maxpacket < 1024)
                ep_conf |= VHUB_EP_CFG_SET_MAX_PKT(maxpacket);
        if (!ep->epn.is_in)
                ep_conf |= VHUB_EP_CFG_DIR_OUT;
        ep_conf |= VHUB_EP_CFG_SET_EP_NUM(usb_endpoint_num(desc));
        ep_conf |= VHUB_EP_CFG_ENABLE;
        ep_conf |= VHUB_EP_CFG_SET_DEV(dev->index + 1);
        EPVDBG(ep, "config=%08x\n", ep_conf);

        spin_lock_irqsave(&vhub->lock, flags);

        /* Disable HW and reset DMA */
        writel(0, ep->epn.regs + AST_VHUB_EP_CONFIG);
        writel(VHUB_EP_DMA_CTRL_RESET,
               ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);

        /* Configure and enable */
        writel(ep_conf, ep->epn.regs + AST_VHUB_EP_CONFIG);

        if (ep->epn.desc_mode) {
                /* Clear DMA status, including the DMA read ptr */
                writel(0, ep->epn.regs + AST_VHUB_EP_DESC_STATUS);

                /* Set descriptor base */
                writel(ep->epn.descs_dma,
                       ep->epn.regs + AST_VHUB_EP_DESC_BASE);

                /* Set base DMA config value */
                ep->epn.dma_conf = VHUB_EP_DMA_DESC_MODE;
                if (ep->epn.is_in)
                        ep->epn.dma_conf |= VHUB_EP_DMA_IN_LONG_MODE;

                /* First reset and disable all operations */
                writel(ep->epn.dma_conf | VHUB_EP_DMA_CTRL_RESET,
                       ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);

                /* Enable descriptor mode */
                writel(ep->epn.dma_conf,
                       ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);
        } else {
                /* Set base DMA config value */
                ep->epn.dma_conf = VHUB_EP_DMA_SINGLE_STAGE;

                /* Reset and switch to single stage mode */
                writel(ep->epn.dma_conf | VHUB_EP_DMA_CTRL_RESET,
                       ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);
                writel(ep->epn.dma_conf,
                       ep->epn.regs + AST_VHUB_EP_DMA_CTLSTAT);
                writel(0, ep->epn.regs + AST_VHUB_EP_DESC_STATUS);
        }

        /* Cleanup data toggle just in case */
        writel(VHUB_EP_TOGGLE_SET_EPNUM(ep->epn.g_idx),
               vhub->regs + AST_VHUB_EP_TOGGLE);

        /* Cleanup and enable ACK interrupt */
        imask = VHUB_EP_IRQ(ep->epn.g_idx);
        writel(imask, vhub->regs + AST_VHUB_EP_ACK_ISR);
        ep_ier = readl(vhub->regs + AST_VHUB_EP_ACK_IER);
        ep_ier |= imask;
        writel(ep_ier, vhub->regs + AST_VHUB_EP_ACK_IER);

        /* Woot, we are online ! */
        ep->epn.enabled = true;

        spin_unlock_irqrestore(&vhub->lock, flags);

        return 0;
}

static void ast_vhub_epn_dispose(struct usb_ep *u_ep)
{
        struct ast_vhub_ep *ep = to_ast_ep(u_ep);

        if (WARN_ON(!ep->dev || !ep->d_idx))
                return;

        EPDBG(ep, "Releasing endpoint\n");

        /* Take it out of the EP list */
        list_del_init(&ep->ep.ep_list);

        /* Mark the address free in the device */
        ep->dev->epns[ep->d_idx - 1] = NULL;

        /* Free name & DMA buffers */
        kfree(ep->ep.name);
        ep->ep.name = NULL;
        dma_free_coherent(&ep->vhub->pdev->dev,
                          AST_VHUB_EPn_MAX_PACKET +
                          8 * AST_VHUB_DESCS_COUNT,
                          ep->buf, ep->buf_dma);
        ep->buf = NULL;
        ep->epn.descs = NULL;

        /* Mark free */
        ep->dev = NULL;
}

static const struct usb_ep_ops ast_vhub_epn_ops = {
        .enable         = ast_vhub_epn_enable,
        .disable        = ast_vhub_epn_disable,
        .dispose        = ast_vhub_epn_dispose,
        .queue          = ast_vhub_epn_queue,
        .dequeue        = ast_vhub_epn_dequeue,
        .set_halt       = ast_vhub_epn_set_halt,
        .set_wedge      = ast_vhub_epn_set_wedge,
        .alloc_request  = ast_vhub_alloc_request,
        .free_request   = ast_vhub_free_request,
};

struct ast_vhub_ep *ast_vhub_alloc_epn(struct ast_vhub_dev *d, u8 addr)
{
        struct ast_vhub *vhub = d->vhub;
        struct ast_vhub_ep *ep;
        unsigned long flags;
        int i;

        /* Find a free one (no device) */
        spin_lock_irqsave(&vhub->lock, flags);
        for (i = 0; i < AST_VHUB_NUM_GEN_EPs; i++)
                if (vhub->epns[i].dev == NULL)
                        break;
        if (i >= AST_VHUB_NUM_GEN_EPs) {
                spin_unlock_irqrestore(&vhub->lock, flags);
                return NULL;
        }

        /* Set it up */
        ep = &vhub->epns[i];
        ep->dev = d;
        spin_unlock_irqrestore(&vhub->lock, flags);

        DDBG(d, "Allocating gen EP %d for addr %d\n", i, addr);
        INIT_LIST_HEAD(&ep->queue);
        ep->d_idx = addr;
        ep->vhub = vhub;
        ep->ep.ops = &ast_vhub_epn_ops;
        ep->ep.name = kasprintf(GFP_KERNEL, "ep%d", addr);
        d->epns[addr-1] = ep;
        ep->epn.g_idx = i;
        ep->epn.regs = vhub->regs + 0x200 + (i * 0x10);

        ep->buf = dma_alloc_coherent(&vhub->pdev->dev,
                                     AST_VHUB_EPn_MAX_PACKET +
                                     8 * AST_VHUB_DESCS_COUNT,
                                     &ep->buf_dma, GFP_KERNEL);
        if (!ep->buf) {
                kfree(ep->ep.name);
                ep->ep.name = NULL;
                return NULL;
        }
        ep->epn.descs = ep->buf + AST_VHUB_EPn_MAX_PACKET;
        ep->epn.descs_dma = ep->buf_dma + AST_VHUB_EPn_MAX_PACKET;

        usb_ep_set_maxpacket_limit(&ep->ep, AST_VHUB_EPn_MAX_PACKET);
        list_add_tail(&ep->ep.ep_list, &d->gadget.ep_list);
        ep->ep.caps.type_iso = true;
        ep->ep.caps.type_bulk = true;
        ep->ep.caps.type_int = true;
        ep->ep.caps.dir_in = true;
        ep->ep.caps.dir_out = true;

        return ep;
}