USB: xhci: Add quirk for Fresco Logic xHCI hardware.

[safe/jmp/linux-2.6] / drivers / usb / host / xhci-hcd.c

/*
 * xHCI host controller driver
 *
 * Copyright (C) 2008 Intel Corp.
 *
 * Author: Sarah Sharp
 * Some code borrowed from the Linux EHCI driver.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/irq.h>
#include <linux/module.h>
#include <linux/moduleparam.h>

#include "xhci.h"

#define DRIVER_AUTHOR "Sarah Sharp"
#define DRIVER_DESC "'eXtensible' Host Controller (xHC) Driver"

/* Some 0.95 hardware can't handle the chain bit on a Link TRB being cleared */
static int link_quirk;
module_param(link_quirk, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(link_quirk, "Don't clear the chain bit on a link TRB");

/* TODO: copied from ehci-hcd.c - can this be refactored? */
/*
 * handshake - spin reading hc until handshake completes or fails
 * @ptr: address of hc register to be read
 * @mask: bits to look at in result of read
 * @done: value of those bits when handshake succeeds
 * @usec: timeout in microseconds
 *
 * Returns negative errno, or zero on success
 *
 * Success happens when the "mask" bits have the specified value (hardware
 * handshake done).  There are two failure modes:  "usec" have passed (major
 * hardware flakeout), or the register reads as all-ones (hardware removed).
 */
static int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
                      u32 mask, u32 done, int usec)
{
        u32     result;

        do {
                result = xhci_readl(xhci, ptr);
                if (result == ~(u32)0)          /* card removed */
                        return -ENODEV;
                result &= mask;
                if (result == done)
                        return 0;
                udelay(1);
                usec--;
        } while (usec > 0);
        return -ETIMEDOUT;
}

/*
 * Force HC into halt state.
 *
 * Disable any IRQs and clear the run/stop bit.
 * HC will complete any current and actively pipelined transactions, and
 * should halt within 16 microframes of the run/stop bit being cleared.
 * Read HC Halted bit in the status register to see when the HC is finished.
 * XXX: shouldn't we set HC_STATE_HALT here somewhere?
 */
int xhci_halt(struct xhci_hcd *xhci)
{
        u32 halted;
        u32 cmd;
        u32 mask;

        xhci_dbg(xhci, "// Halt the HC\n");
        /* Disable all interrupts from the host controller */
        mask = ~(XHCI_IRQS);
        halted = xhci_readl(xhci, &xhci->op_regs->status) & STS_HALT;
        if (!halted)
                mask &= ~CMD_RUN;

        cmd = xhci_readl(xhci, &xhci->op_regs->command);
        cmd &= mask;
        xhci_writel(xhci, cmd, &xhci->op_regs->command);

        return handshake(xhci, &xhci->op_regs->status,
                        STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
}

/*
 * Reset a halted HC, and set the internal HC state to HC_STATE_HALT.
 *
 * This resets pipelines, timers, counters, state machines, etc.
 * Transactions will be terminated immediately, and operational registers
 * will be set to their defaults.
 */
int xhci_reset(struct xhci_hcd *xhci)
{
        u32 command;
        u32 state;

        state = xhci_readl(xhci, &xhci->op_regs->status);
        if ((state & STS_HALT) == 0) {
                xhci_warn(xhci, "Host controller not halted, aborting reset.\n");
                return 0;
        }

        xhci_dbg(xhci, "// Reset the HC\n");
        command = xhci_readl(xhci, &xhci->op_regs->command);
        command |= CMD_RESET;
        xhci_writel(xhci, command, &xhci->op_regs->command);
        /* XXX: Why does EHCI set this here?  Shouldn't other code do this? */
        xhci_to_hcd(xhci)->state = HC_STATE_HALT;

        return handshake(xhci, &xhci->op_regs->command, CMD_RESET, 0, 250 * 1000);
}

/*
 * Stop the HC from processing the endpoint queues.
 */
static void xhci_quiesce(struct xhci_hcd *xhci)
{
        /*
         * Queues are per endpoint, so we need to disable an endpoint or slot.
         *
         * To disable a slot, we need to insert a disable slot command on the
         * command ring and ring the doorbell.  This will also free any internal
         * resources associated with the slot (which might not be what we want).
         *
         * A Release Endpoint command sounds better - doesn't free internal HC
         * memory, but removes the endpoints from the schedule and releases the
         * bandwidth, disables the doorbells, and clears the endpoint enable
         * flag.  Usually used prior to a set interface command.
         *
         * TODO: Implement after command ring code is done.
         */
        BUG_ON(!HC_IS_RUNNING(xhci_to_hcd(xhci)->state));
        xhci_dbg(xhci, "Finished quiescing -- code not written yet\n");
}

#if 0
/* Set up MSI-X table for entry 0 (may claim other entries later) */
static int xhci_setup_msix(struct xhci_hcd *xhci)
{
        int ret;
        struct pci_dev *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);

        xhci->msix_count = 0;
        /* XXX: did I do this right?  ixgbe does kcalloc for more than one */
        xhci->msix_entries = kmalloc(sizeof(struct msix_entry), GFP_KERNEL);
        if (!xhci->msix_entries) {
                xhci_err(xhci, "Failed to allocate MSI-X entries\n");
                return -ENOMEM;
        }
        xhci->msix_entries[0].entry = 0;

        ret = pci_enable_msix(pdev, xhci->msix_entries, xhci->msix_count);
        if (ret) {
                xhci_err(xhci, "Failed to enable MSI-X\n");
                goto free_entries;
        }

        /*
         * Pass the xhci pointer value as the request_irq "cookie".
         * If more irqs are added, this will need to be unique for each one.
         */
        ret = request_irq(xhci->msix_entries[0].vector, &xhci_irq, 0,
                        "xHCI", xhci_to_hcd(xhci));
        if (ret) {
                xhci_err(xhci, "Failed to allocate MSI-X interrupt\n");
                goto disable_msix;
        }
        xhci_dbg(xhci, "Finished setting up MSI-X\n");
        return 0;

disable_msix:
        pci_disable_msix(pdev);
free_entries:
        kfree(xhci->msix_entries);
        xhci->msix_entries = NULL;
        return ret;
}

/* XXX: code duplication; can xhci_setup_msix call this? */
/* Free any IRQs and disable MSI-X */
static void xhci_cleanup_msix(struct xhci_hcd *xhci)
{
        struct pci_dev *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
        if (!xhci->msix_entries)
                return;

        free_irq(xhci->msix_entries[0].vector, xhci);
        pci_disable_msix(pdev);
        kfree(xhci->msix_entries);
        xhci->msix_entries = NULL;
        xhci_dbg(xhci, "Finished cleaning up MSI-X\n");
}
#endif

/*
 * Initialize memory for HCD and xHC (one-time init).
 *
 * Program the PAGESIZE register, initialize the device context array, create
 * device contexts (?), set up a command ring segment (or two?), create event
 * ring (one for now).
 */
int xhci_init(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        int retval = 0;

        xhci_dbg(xhci, "xhci_init\n");
        spin_lock_init(&xhci->lock);
        if (link_quirk) {
                xhci_dbg(xhci, "QUIRK: Not clearing Link TRB chain bits.\n");
                xhci->quirks |= XHCI_LINK_TRB_QUIRK;
        } else {
                xhci_dbg(xhci, "xHCI doesn't need link TRB QUIRK\n");
        }
        retval = xhci_mem_init(xhci, GFP_KERNEL);
        xhci_dbg(xhci, "Finished xhci_init\n");

        return retval;
}

/*
 * Called in interrupt context when there might be work
 * queued on the event ring
 *
 * xhci->lock must be held by caller.
 */
static void xhci_work(struct xhci_hcd *xhci)
{
        u32 temp;
        u64 temp_64;

        /*
         * Clear the op reg interrupt status first,
         * so we can receive interrupts from other MSI-X interrupters.
         * Write 1 to clear the interrupt status.
         */
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        temp |= STS_EINT;
        xhci_writel(xhci, temp, &xhci->op_regs->status);
        /* FIXME when MSI-X is supported and there are multiple vectors */
        /* Clear the MSI-X event interrupt status */

        /* Acknowledge the interrupt */
        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        temp |= 0x3;
        xhci_writel(xhci, temp, &xhci->ir_set->irq_pending);
        /* Flush posted writes */
        xhci_readl(xhci, &xhci->ir_set->irq_pending);

        /* FIXME this should be a delayed service routine that clears the EHB */
        xhci_handle_event(xhci);

        /* Clear the event handler busy flag (RW1C); the event ring should be empty. */
        temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
        xhci_write_64(xhci, temp_64 | ERST_EHB, &xhci->ir_set->erst_dequeue);
        /* Flush posted writes -- FIXME is this necessary? */
        xhci_readl(xhci, &xhci->ir_set->irq_pending);
}

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

/*
 * xHCI spec says we can get an interrupt, and if the HC has an error condition,
 * we might get bad data out of the event ring.  Section 4.10.2.7 has a list of
 * indicators of an event TRB error, but we check the status *first* to be safe.
 */
irqreturn_t xhci_irq(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        u32 temp, temp2;
        union xhci_trb *trb;

        spin_lock(&xhci->lock);
        trb = xhci->event_ring->dequeue;
        /* Check if the xHC generated the interrupt, or the irq is shared */
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        temp2 = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        if (temp == 0xffffffff && temp2 == 0xffffffff)
                goto hw_died;

        if (!(temp & STS_EINT) && !ER_IRQ_PENDING(temp2)) {
                spin_unlock(&xhci->lock);
                return IRQ_NONE;
        }
        xhci_dbg(xhci, "op reg status = %08x\n", temp);
        xhci_dbg(xhci, "ir set irq_pending = %08x\n", temp2);
        xhci_dbg(xhci, "Event ring dequeue ptr:\n");
        xhci_dbg(xhci, "@%llx %08x %08x %08x %08x\n",
                        (unsigned long long)xhci_trb_virt_to_dma(xhci->event_ring->deq_seg, trb),
                        lower_32_bits(trb->link.segment_ptr),
                        upper_32_bits(trb->link.segment_ptr),
                        (unsigned int) trb->link.intr_target,
                        (unsigned int) trb->link.control);

        if (temp & STS_FATAL) {
                xhci_warn(xhci, "WARNING: Host System Error\n");
                xhci_halt(xhci);
hw_died:
                xhci_to_hcd(xhci)->state = HC_STATE_HALT;
                spin_unlock(&xhci->lock);
                return -ESHUTDOWN;
        }

        xhci_work(xhci);
        spin_unlock(&xhci->lock);

        return IRQ_HANDLED;
}

#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
void xhci_event_ring_work(unsigned long arg)
{
        unsigned long flags;
        int temp;
        u64 temp_64;
        struct xhci_hcd *xhci = (struct xhci_hcd *) arg;
        int i, j;

        xhci_dbg(xhci, "Poll event ring: %lu\n", jiffies);

        spin_lock_irqsave(&xhci->lock, flags);
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        xhci_dbg(xhci, "op reg status = 0x%x\n", temp);
        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci_dbg(xhci, "ir_set 0 pending = 0x%x\n", temp);
        xhci_dbg(xhci, "No-op commands handled = %d\n", xhci->noops_handled);
        xhci_dbg(xhci, "HC error bitmask = 0x%x\n", xhci->error_bitmask);
        xhci->error_bitmask = 0;
        xhci_dbg(xhci, "Event ring:\n");
        xhci_debug_segment(xhci, xhci->event_ring->deq_seg);
        xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
        temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
        temp_64 &= ~ERST_PTR_MASK;
        xhci_dbg(xhci, "ERST deq = 64'h%0lx\n", (long unsigned int) temp_64);
        xhci_dbg(xhci, "Command ring:\n");
        xhci_debug_segment(xhci, xhci->cmd_ring->deq_seg);
        xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
        xhci_dbg_cmd_ptrs(xhci);
        for (i = 0; i < MAX_HC_SLOTS; ++i) {
                if (xhci->devs[i]) {
                        for (j = 0; j < 31; ++j) {
                                if (xhci->devs[i]->ep_rings[j]) {
                                        xhci_dbg(xhci, "Dev %d endpoint ring %d:\n", i, j);
                                        xhci_debug_segment(xhci, xhci->devs[i]->ep_rings[j]->deq_seg);
                                }
                        }
                }
        }

        if (xhci->noops_submitted != NUM_TEST_NOOPS)
                if (xhci_setup_one_noop(xhci))
                        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        if (!xhci->zombie)
                mod_timer(&xhci->event_ring_timer, jiffies + POLL_TIMEOUT * HZ);
        else
                xhci_dbg(xhci, "Quit polling the event ring.\n");
}
#endif

/*
 * Start the HC after it was halted.
 *
 * This function is called by the USB core when the HC driver is added.
 * Its opposite is xhci_stop().
 *
 * xhci_init() must be called once before this function can be called.
 * Reset the HC, enable device slot contexts, program DCBAAP, and
 * set command ring pointer and event ring pointer.
 *
 * Setup MSI-X vectors and enable interrupts.
 */
int xhci_run(struct usb_hcd *hcd)
{
        u32 temp;
        u64 temp_64;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        void (*doorbell)(struct xhci_hcd *) = NULL;

        hcd->uses_new_polling = 1;
        hcd->poll_rh = 0;

        xhci_dbg(xhci, "xhci_run\n");
#if 0   /* FIXME: MSI not setup yet */
        /* Do this at the very last minute */
        ret = xhci_setup_msix(xhci);
        if (!ret)
                return ret;

        return -ENOSYS;
#endif
#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
        init_timer(&xhci->event_ring_timer);
        xhci->event_ring_timer.data = (unsigned long) xhci;
        xhci->event_ring_timer.function = xhci_event_ring_work;
        /* Poll the event ring */
        xhci->event_ring_timer.expires = jiffies + POLL_TIMEOUT * HZ;
        xhci->zombie = 0;
        xhci_dbg(xhci, "Setting event ring polling timer\n");
        add_timer(&xhci->event_ring_timer);
#endif

        xhci_dbg(xhci, "Command ring memory map follows:\n");
        xhci_debug_ring(xhci, xhci->cmd_ring);
        xhci_dbg_ring_ptrs(xhci, xhci->cmd_ring);
        xhci_dbg_cmd_ptrs(xhci);

        xhci_dbg(xhci, "ERST memory map follows:\n");
        xhci_dbg_erst(xhci, &xhci->erst);
        xhci_dbg(xhci, "Event ring:\n");
        xhci_debug_ring(xhci, xhci->event_ring);
        xhci_dbg_ring_ptrs(xhci, xhci->event_ring);
        temp_64 = xhci_read_64(xhci, &xhci->ir_set->erst_dequeue);
        temp_64 &= ~ERST_PTR_MASK;
        xhci_dbg(xhci, "ERST deq = 64'h%0lx\n", (long unsigned int) temp_64);

        xhci_dbg(xhci, "// Set the interrupt modulation register\n");
        temp = xhci_readl(xhci, &xhci->ir_set->irq_control);
        temp &= ~ER_IRQ_INTERVAL_MASK;
        temp |= (u32) 160;
        xhci_writel(xhci, temp, &xhci->ir_set->irq_control);

        /* Set the HCD state before we enable the irqs */
        hcd->state = HC_STATE_RUNNING;
        temp = xhci_readl(xhci, &xhci->op_regs->command);
        temp |= (CMD_EIE);
        xhci_dbg(xhci, "// Enable interrupts, cmd = 0x%x.\n",
                        temp);
        xhci_writel(xhci, temp, &xhci->op_regs->command);

        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci_dbg(xhci, "// Enabling event ring interrupter %p by writing 0x%x to irq_pending\n",
                        xhci->ir_set, (unsigned int) ER_IRQ_ENABLE(temp));
        xhci_writel(xhci, ER_IRQ_ENABLE(temp),
                        &xhci->ir_set->irq_pending);
        xhci_print_ir_set(xhci, xhci->ir_set, 0);

        if (NUM_TEST_NOOPS > 0)
                doorbell = xhci_setup_one_noop(xhci);

        temp = xhci_readl(xhci, &xhci->op_regs->command);
        temp |= (CMD_RUN);
        xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n",
                        temp);
        xhci_writel(xhci, temp, &xhci->op_regs->command);
        /* Flush PCI posted writes */
        temp = xhci_readl(xhci, &xhci->op_regs->command);
        xhci_dbg(xhci, "// @%p = 0x%x\n", &xhci->op_regs->command, temp);
        if (doorbell)
                (*doorbell)(xhci);

        xhci_dbg(xhci, "Finished xhci_run\n");
        return 0;
}

/*
 * Stop xHCI driver.
 *
 * This function is called by the USB core when the HC driver is removed.
 * Its opposite is xhci_run().
 *
 * Disable device contexts, disable IRQs, and quiesce the HC.
 * Reset the HC, finish any completed transactions, and cleanup memory.
 */
void xhci_stop(struct usb_hcd *hcd)
{
        u32 temp;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);

        spin_lock_irq(&xhci->lock);
        if (HC_IS_RUNNING(hcd->state))
                xhci_quiesce(xhci);
        xhci_halt(xhci);
        xhci_reset(xhci);
        spin_unlock_irq(&xhci->lock);

#if 0   /* No MSI yet */
        xhci_cleanup_msix(xhci);
#endif
#ifdef CONFIG_USB_XHCI_HCD_DEBUGGING
        /* Tell the event ring poll function not to reschedule */
        xhci->zombie = 1;
        del_timer_sync(&xhci->event_ring_timer);
#endif

        xhci_dbg(xhci, "// Disabling event ring interrupts\n");
        temp = xhci_readl(xhci, &xhci->op_regs->status);
        xhci_writel(xhci, temp & ~STS_EINT, &xhci->op_regs->status);
        temp = xhci_readl(xhci, &xhci->ir_set->irq_pending);
        xhci_writel(xhci, ER_IRQ_DISABLE(temp),
                        &xhci->ir_set->irq_pending);
        xhci_print_ir_set(xhci, xhci->ir_set, 0);

        xhci_dbg(xhci, "cleaning up memory\n");
        xhci_mem_cleanup(xhci);
        xhci_dbg(xhci, "xhci_stop completed - status = %x\n",
                    xhci_readl(xhci, &xhci->op_regs->status));
}

/*
 * Shutdown HC (not bus-specific)
 *
 * This is called when the machine is rebooting or halting.  We assume that the
 * machine will be powered off, and the HC's internal state will be reset.
 * Don't bother to free memory.
 */
void xhci_shutdown(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);

        spin_lock_irq(&xhci->lock);
        xhci_halt(xhci);
        spin_unlock_irq(&xhci->lock);

#if 0
        xhci_cleanup_msix(xhci);
#endif

        xhci_dbg(xhci, "xhci_shutdown completed - status = %x\n",
                    xhci_readl(xhci, &xhci->op_regs->status));
}

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

/**
 * xhci_get_endpoint_index - Used for passing endpoint bitmasks between the core and
 * HCDs.  Find the index for an endpoint given its descriptor.  Use the return
 * value to right shift 1 for the bitmask.
 *
 * Index  = (epnum * 2) + direction - 1,
 * where direction = 0 for OUT, 1 for IN.
 * For control endpoints, the IN index is used (OUT index is unused), so
 * index = (epnum * 2) + direction - 1 = (epnum * 2) + 1 - 1 = (epnum * 2)
 */
unsigned int xhci_get_endpoint_index(struct usb_endpoint_descriptor *desc)
{
        unsigned int index;
        if (usb_endpoint_xfer_control(desc))
                index = (unsigned int) (usb_endpoint_num(desc)*2);
        else
                index = (unsigned int) (usb_endpoint_num(desc)*2) +
                        (usb_endpoint_dir_in(desc) ? 1 : 0) - 1;
        return index;
}

/* Find the flag for this endpoint (for use in the control context).  Use the
 * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
 * bit 1, etc.
 */
unsigned int xhci_get_endpoint_flag(struct usb_endpoint_descriptor *desc)
{
        return 1 << (xhci_get_endpoint_index(desc) + 1);
}

/* Find the flag for this endpoint (for use in the control context).  Use the
 * endpoint index to create a bitmask.  The slot context is bit 0, endpoint 0 is
 * bit 1, etc.
 */
unsigned int xhci_get_endpoint_flag_from_index(unsigned int ep_index)
{
        return 1 << (ep_index + 1);
}

/* Compute the last valid endpoint context index.  Basically, this is the
 * endpoint index plus one.  For slot contexts with more than valid endpoint,
 * we find the most significant bit set in the added contexts flags.
 * e.g. ep 1 IN (with epnum 0x81) => added_ctxs = 0b1000
 * fls(0b1000) = 4, but the endpoint context index is 3, so subtract one.
 */
unsigned int xhci_last_valid_endpoint(u32 added_ctxs)
{
        return fls(added_ctxs) - 1;
}

/* Returns 1 if the arguments are OK;
 * returns 0 this is a root hub; returns -EINVAL for NULL pointers.
 */
int xhci_check_args(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint *ep, int check_ep, const char *func) {
        if (!hcd || (check_ep && !ep) || !udev) {
                printk(KERN_DEBUG "xHCI %s called with invalid args\n",
                                func);
                return -EINVAL;
        }
        if (!udev->parent) {
                printk(KERN_DEBUG "xHCI %s called for root hub\n",
                                func);
                return 0;
        }
        if (!udev->slot_id) {
                printk(KERN_DEBUG "xHCI %s called with unaddressed device\n",
                                func);
                return -EINVAL;
        }
        return 1;
}

static int xhci_configure_endpoint(struct xhci_hcd *xhci,
                struct usb_device *udev, struct xhci_virt_device *virt_dev,
                bool ctx_change);

/*
 * Full speed devices may have a max packet size greater than 8 bytes, but the
 * USB core doesn't know that until it reads the first 8 bytes of the
 * descriptor.  If the usb_device's max packet size changes after that point,
 * we need to issue an evaluate context command and wait on it.
 */
static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
                unsigned int ep_index, struct urb *urb)
{
        struct xhci_container_ctx *in_ctx;
        struct xhci_container_ctx *out_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_ep_ctx *ep_ctx;
        int max_packet_size;
        int hw_max_packet_size;
        int ret = 0;

        out_ctx = xhci->devs[slot_id]->out_ctx;
        ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
        hw_max_packet_size = MAX_PACKET_DECODED(ep_ctx->ep_info2);
        max_packet_size = urb->dev->ep0.desc.wMaxPacketSize;
        if (hw_max_packet_size != max_packet_size) {
                xhci_dbg(xhci, "Max Packet Size for ep 0 changed.\n");
                xhci_dbg(xhci, "Max packet size in usb_device = %d\n",
                                max_packet_size);
                xhci_dbg(xhci, "Max packet size in xHCI HW = %d\n",
                                hw_max_packet_size);
                xhci_dbg(xhci, "Issuing evaluate context command.\n");

                /* Set up the modified control endpoint 0 */
                xhci_endpoint_copy(xhci, xhci->devs[slot_id], ep_index);
                in_ctx = xhci->devs[slot_id]->in_ctx;
                ep_ctx = xhci_get_ep_ctx(xhci, in_ctx, ep_index);
                ep_ctx->ep_info2 &= ~MAX_PACKET_MASK;
                ep_ctx->ep_info2 |= MAX_PACKET(max_packet_size);

                /* Set up the input context flags for the command */
                /* FIXME: This won't work if a non-default control endpoint
                 * changes max packet sizes.
                 */
                ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
                ctrl_ctx->add_flags = EP0_FLAG;
                ctrl_ctx->drop_flags = 0;

                xhci_dbg(xhci, "Slot %d input context\n", slot_id);
                xhci_dbg_ctx(xhci, in_ctx, ep_index);
                xhci_dbg(xhci, "Slot %d output context\n", slot_id);
                xhci_dbg_ctx(xhci, out_ctx, ep_index);

                ret = xhci_configure_endpoint(xhci, urb->dev,
                                xhci->devs[slot_id], true);

                /* Clean up the input context for later use by bandwidth
                 * functions.
                 */
                ctrl_ctx->add_flags = SLOT_FLAG;
        }
        return ret;
}

/*
 * non-error returns are a promise to giveback() the urb later
 * we drop ownership so next owner (or urb unlink) can get it
 */
int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        unsigned long flags;
        int ret = 0;
        unsigned int slot_id, ep_index;


        if (!urb || xhci_check_args(hcd, urb->dev, urb->ep, true, __func__) <= 0)
                return -EINVAL;

        slot_id = urb->dev->slot_id;
        ep_index = xhci_get_endpoint_index(&urb->ep->desc);

        if (!xhci->devs || !xhci->devs[slot_id]) {
                if (!in_interrupt())
                        dev_warn(&urb->dev->dev, "WARN: urb submitted for dev with no Slot ID\n");
                ret = -EINVAL;
                goto exit;
        }
        if (!test_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags)) {
                if (!in_interrupt())
                        xhci_dbg(xhci, "urb submitted during PCI suspend\n");
                ret = -ESHUTDOWN;
                goto exit;
        }
        if (usb_endpoint_xfer_control(&urb->ep->desc)) {
                /* Check to see if the max packet size for the default control
                 * endpoint changed during FS device enumeration
                 */
                if (urb->dev->speed == USB_SPEED_FULL) {
                        ret = xhci_check_maxpacket(xhci, slot_id,
                                        ep_index, urb);
                        if (ret < 0)
                                return ret;
                }

                /* We have a spinlock and interrupts disabled, so we must pass
                 * atomic context to this function, which may allocate memory.
                 */
                spin_lock_irqsave(&xhci->lock, flags);
                ret = xhci_queue_ctrl_tx(xhci, GFP_ATOMIC, urb,
                                slot_id, ep_index);
                spin_unlock_irqrestore(&xhci->lock, flags);
        } else if (usb_endpoint_xfer_bulk(&urb->ep->desc)) {
                spin_lock_irqsave(&xhci->lock, flags);
                ret = xhci_queue_bulk_tx(xhci, GFP_ATOMIC, urb,
                                slot_id, ep_index);
                spin_unlock_irqrestore(&xhci->lock, flags);
        } else {
                ret = -EINVAL;
        }
exit:
        return ret;
}

/*
 * Remove the URB's TD from the endpoint ring.  This may cause the HC to stop
 * USB transfers, potentially stopping in the middle of a TRB buffer.  The HC
 * should pick up where it left off in the TD, unless a Set Transfer Ring
 * Dequeue Pointer is issued.
 *
 * The TRBs that make up the buffers for the canceled URB will be "removed" from
 * the ring.  Since the ring is a contiguous structure, they can't be physically
 * removed.  Instead, there are two options:
 *
 *  1) If the HC is in the middle of processing the URB to be canceled, we
 *     simply move the ring's dequeue pointer past those TRBs using the Set
 *     Transfer Ring Dequeue Pointer command.  This will be the common case,
 *     when drivers timeout on the last submitted URB and attempt to cancel.
 *
 *  2) If the HC is in the middle of a different TD, we turn the TRBs into a
 *     series of 1-TRB transfer no-op TDs.  (No-ops shouldn't be chained.)  The
 *     HC will need to invalidate the any TRBs it has cached after the stop
 *     endpoint command, as noted in the xHCI 0.95 errata.
 *
 *  3) The TD may have completed by the time the Stop Endpoint Command
 *     completes, so software needs to handle that case too.
 *
 * This function should protect against the TD enqueueing code ringing the
 * doorbell while this code is waiting for a Stop Endpoint command to complete.
 * It also needs to account for multiple cancellations on happening at the same
 * time for the same endpoint.
 *
 * Note that this function can be called in any context, or so says
 * usb_hcd_unlink_urb()
 */
int xhci_urb_dequeue(struct usb_hcd *hcd, struct urb *urb, int status)
{
        unsigned long flags;
        int ret;
        struct xhci_hcd *xhci;
        struct xhci_td *td;
        unsigned int ep_index;
        struct xhci_ring *ep_ring;

        xhci = hcd_to_xhci(hcd);
        spin_lock_irqsave(&xhci->lock, flags);
        /* Make sure the URB hasn't completed or been unlinked already */
        ret = usb_hcd_check_unlink_urb(hcd, urb, status);
        if (ret || !urb->hcpriv)
                goto done;

        xhci_dbg(xhci, "Cancel URB %p\n", urb);
        xhci_dbg(xhci, "Event ring:\n");
        xhci_debug_ring(xhci, xhci->event_ring);
        ep_index = xhci_get_endpoint_index(&urb->ep->desc);
        ep_ring = xhci->devs[urb->dev->slot_id]->ep_rings[ep_index];
        xhci_dbg(xhci, "Endpoint ring:\n");
        xhci_debug_ring(xhci, ep_ring);
        td = (struct xhci_td *) urb->hcpriv;

        ep_ring->cancels_pending++;
        list_add_tail(&td->cancelled_td_list, &ep_ring->cancelled_td_list);
        /* Queue a stop endpoint command, but only if this is
         * the first cancellation to be handled.
         */
        if (ep_ring->cancels_pending == 1) {
                xhci_queue_stop_endpoint(xhci, urb->dev->slot_id, ep_index);
                xhci_ring_cmd_db(xhci);
        }
done:
        spin_unlock_irqrestore(&xhci->lock, flags);
        return ret;
}

/* Drop an endpoint from a new bandwidth configuration for this device.
 * Only one call to this function is allowed per endpoint before
 * check_bandwidth() or reset_bandwidth() must be called.
 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
 * add the endpoint to the schedule with possibly new parameters denoted by a
 * different endpoint descriptor in usb_host_endpoint.
 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
 * not allowed.
 *
 * The USB core will not allow URBs to be queued to an endpoint that is being
 * disabled, so there's no need for mutual exclusion to protect
 * the xhci->devs[slot_id] structure.
 */
int xhci_drop_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci;
        struct xhci_container_ctx *in_ctx, *out_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_slot_ctx *slot_ctx;
        unsigned int last_ctx;
        unsigned int ep_index;
        struct xhci_ep_ctx *ep_ctx;
        u32 drop_flag;
        u32 new_add_flags, new_drop_flags, new_slot_info;
        int ret;

        ret = xhci_check_args(hcd, udev, ep, 1, __func__);
        if (ret <= 0)
                return ret;
        xhci = hcd_to_xhci(hcd);
        xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);

        drop_flag = xhci_get_endpoint_flag(&ep->desc);
        if (drop_flag == SLOT_FLAG || drop_flag == EP0_FLAG) {
                xhci_dbg(xhci, "xHCI %s - can't drop slot or ep 0 %#x\n",
                                __func__, drop_flag);
                return 0;
        }

        if (!xhci->devs || !xhci->devs[udev->slot_id]) {
                xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
                                __func__);
                return -EINVAL;
        }

        in_ctx = xhci->devs[udev->slot_id]->in_ctx;
        out_ctx = xhci->devs[udev->slot_id]->out_ctx;
        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
        /* If the HC already knows the endpoint is disabled,
         * or the HCD has noted it is disabled, ignore this request
         */
        if ((ep_ctx->ep_info & EP_STATE_MASK) == EP_STATE_DISABLED ||
                        ctrl_ctx->drop_flags & xhci_get_endpoint_flag(&ep->desc)) {
                xhci_warn(xhci, "xHCI %s called with disabled ep %p\n",
                                __func__, ep);
                return 0;
        }

        ctrl_ctx->drop_flags |= drop_flag;
        new_drop_flags = ctrl_ctx->drop_flags;

        ctrl_ctx->add_flags = ~drop_flag;
        new_add_flags = ctrl_ctx->add_flags;

        last_ctx = xhci_last_valid_endpoint(ctrl_ctx->add_flags);
        slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
        /* Update the last valid endpoint context, if we deleted the last one */
        if ((slot_ctx->dev_info & LAST_CTX_MASK) > LAST_CTX(last_ctx)) {
                slot_ctx->dev_info &= ~LAST_CTX_MASK;
                slot_ctx->dev_info |= LAST_CTX(last_ctx);
        }
        new_slot_info = slot_ctx->dev_info;

        xhci_endpoint_zero(xhci, xhci->devs[udev->slot_id], ep);

        xhci_dbg(xhci, "drop ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
                        (unsigned int) ep->desc.bEndpointAddress,
                        udev->slot_id,
                        (unsigned int) new_drop_flags,
                        (unsigned int) new_add_flags,
                        (unsigned int) new_slot_info);
        return 0;
}

/* Add an endpoint to a new possible bandwidth configuration for this device.
 * Only one call to this function is allowed per endpoint before
 * check_bandwidth() or reset_bandwidth() must be called.
 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
 * add the endpoint to the schedule with possibly new parameters denoted by a
 * different endpoint descriptor in usb_host_endpoint.
 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
 * not allowed.
 *
 * The USB core will not allow URBs to be queued to an endpoint until the
 * configuration or alt setting is installed in the device, so there's no need
 * for mutual exclusion to protect the xhci->devs[slot_id] structure.
 */
int xhci_add_endpoint(struct usb_hcd *hcd, struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci;
        struct xhci_container_ctx *in_ctx, *out_ctx;
        unsigned int ep_index;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_slot_ctx *slot_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        u32 added_ctxs;
        unsigned int last_ctx;
        u32 new_add_flags, new_drop_flags, new_slot_info;
        int ret = 0;

        ret = xhci_check_args(hcd, udev, ep, 1, __func__);
        if (ret <= 0) {
                /* So we won't queue a reset ep command for a root hub */
                ep->hcpriv = NULL;
                return ret;
        }
        xhci = hcd_to_xhci(hcd);

        added_ctxs = xhci_get_endpoint_flag(&ep->desc);
        last_ctx = xhci_last_valid_endpoint(added_ctxs);
        if (added_ctxs == SLOT_FLAG || added_ctxs == EP0_FLAG) {
                /* FIXME when we have to issue an evaluate endpoint command to
                 * deal with ep0 max packet size changing once we get the
                 * descriptors
                 */
                xhci_dbg(xhci, "xHCI %s - can't add slot or ep 0 %#x\n",
                                __func__, added_ctxs);
                return 0;
        }

        if (!xhci->devs || !xhci->devs[udev->slot_id]) {
                xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
                                __func__);
                return -EINVAL;
        }

        in_ctx = xhci->devs[udev->slot_id]->in_ctx;
        out_ctx = xhci->devs[udev->slot_id]->out_ctx;
        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = xhci_get_ep_ctx(xhci, out_ctx, ep_index);
        /* If the HCD has already noted the endpoint is enabled,
         * ignore this request.
         */
        if (ctrl_ctx->add_flags & xhci_get_endpoint_flag(&ep->desc)) {
                xhci_warn(xhci, "xHCI %s called with enabled ep %p\n",
                                __func__, ep);
                return 0;
        }

        /*
         * Configuration and alternate setting changes must be done in
         * process context, not interrupt context (or so documenation
         * for usb_set_interface() and usb_set_configuration() claim).
         */
        if (xhci_endpoint_init(xhci, xhci->devs[udev->slot_id],
                                udev, ep, GFP_KERNEL) < 0) {
                dev_dbg(&udev->dev, "%s - could not initialize ep %#x\n",
                                __func__, ep->desc.bEndpointAddress);
                return -ENOMEM;
        }

        ctrl_ctx->add_flags |= added_ctxs;
        new_add_flags = ctrl_ctx->add_flags;

        /* If xhci_endpoint_disable() was called for this endpoint, but the
         * xHC hasn't been notified yet through the check_bandwidth() call,
         * this re-adds a new state for the endpoint from the new endpoint
         * descriptors.  We must drop and re-add this endpoint, so we leave the
         * drop flags alone.
         */
        new_drop_flags = ctrl_ctx->drop_flags;

        slot_ctx = xhci_get_slot_ctx(xhci, in_ctx);
        /* Update the last valid endpoint context, if we just added one past */
        if ((slot_ctx->dev_info & LAST_CTX_MASK) < LAST_CTX(last_ctx)) {
                slot_ctx->dev_info &= ~LAST_CTX_MASK;
                slot_ctx->dev_info |= LAST_CTX(last_ctx);
        }
        new_slot_info = slot_ctx->dev_info;

        /* Store the usb_device pointer for later use */
        ep->hcpriv = udev;

        xhci_dbg(xhci, "add ep 0x%x, slot id %d, new drop flags = %#x, new add flags = %#x, new slot info = %#x\n",
                        (unsigned int) ep->desc.bEndpointAddress,
                        udev->slot_id,
                        (unsigned int) new_drop_flags,
                        (unsigned int) new_add_flags,
                        (unsigned int) new_slot_info);
        return 0;
}

static void xhci_zero_in_ctx(struct xhci_hcd *xhci, struct xhci_virt_device *virt_dev)
{
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_slot_ctx *slot_ctx;
        int i;

        /* When a device's add flag and drop flag are zero, any subsequent
         * configure endpoint command will leave that endpoint's state
         * untouched.  Make sure we don't leave any old state in the input
         * endpoint contexts.
         */
        ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
        ctrl_ctx->drop_flags = 0;
        ctrl_ctx->add_flags = 0;
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
        slot_ctx->dev_info &= ~LAST_CTX_MASK;
        /* Endpoint 0 is always valid */
        slot_ctx->dev_info |= LAST_CTX(1);
        for (i = 1; i < 31; ++i) {
                ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->in_ctx, i);
                ep_ctx->ep_info = 0;
                ep_ctx->ep_info2 = 0;
                ep_ctx->deq = 0;
                ep_ctx->tx_info = 0;
        }
}

static int xhci_configure_endpoint_result(struct xhci_hcd *xhci,
                struct usb_device *udev, struct xhci_virt_device *virt_dev)
{
        int ret;

        switch (virt_dev->cmd_status) {
        case COMP_ENOMEM:
                dev_warn(&udev->dev, "Not enough host controller resources "
                                "for new device state.\n");
                ret = -ENOMEM;
                /* FIXME: can we allocate more resources for the HC? */
                break;
        case COMP_BW_ERR:
                dev_warn(&udev->dev, "Not enough bandwidth "
                                "for new device state.\n");
                ret = -ENOSPC;
                /* FIXME: can we go back to the old state? */
                break;
        case COMP_TRB_ERR:
                /* the HCD set up something wrong */
                dev_warn(&udev->dev, "ERROR: Endpoint drop flag = 0, "
                                "add flag = 1, "
                                "and endpoint is not disabled.\n");
                ret = -EINVAL;
                break;
        case COMP_SUCCESS:
                dev_dbg(&udev->dev, "Successful Endpoint Configure command\n");
                ret = 0;
                break;
        default:
                xhci_err(xhci, "ERROR: unexpected command completion "
                                "code 0x%x.\n", virt_dev->cmd_status);
                ret = -EINVAL;
                break;
        }
        return ret;
}

static int xhci_evaluate_context_result(struct xhci_hcd *xhci,
                struct usb_device *udev, struct xhci_virt_device *virt_dev)
{
        int ret;

        switch (virt_dev->cmd_status) {
        case COMP_EINVAL:
                dev_warn(&udev->dev, "WARN: xHCI driver setup invalid evaluate "
                                "context command.\n");
                ret = -EINVAL;
                break;
        case COMP_EBADSLT:
                dev_warn(&udev->dev, "WARN: slot not enabled for"
                                "evaluate context command.\n");
        case COMP_CTX_STATE:
                dev_warn(&udev->dev, "WARN: invalid context state for "
                                "evaluate context command.\n");
                xhci_dbg_ctx(xhci, virt_dev->out_ctx, 1);
                ret = -EINVAL;
                break;
        case COMP_SUCCESS:
                dev_dbg(&udev->dev, "Successful evaluate context command\n");
                ret = 0;
                break;
        default:
                xhci_err(xhci, "ERROR: unexpected command completion "
                                "code 0x%x.\n", virt_dev->cmd_status);
                ret = -EINVAL;
                break;
        }
        return ret;
}

/* Issue a configure endpoint command or evaluate context command
 * and wait for it to finish.
 */
static int xhci_configure_endpoint(struct xhci_hcd *xhci,
                struct usb_device *udev, struct xhci_virt_device *virt_dev,
                bool ctx_change)
{
        int ret;
        int timeleft;
        unsigned long flags;

        spin_lock_irqsave(&xhci->lock, flags);
        if (!ctx_change)
                ret = xhci_queue_configure_endpoint(xhci, virt_dev->in_ctx->dma,
                                udev->slot_id);
        else
                ret = xhci_queue_evaluate_context(xhci, virt_dev->in_ctx->dma,
                                udev->slot_id);
        if (ret < 0) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME allocate a new ring segment\n");
                return -ENOMEM;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* Wait for the configure endpoint command to complete */
        timeleft = wait_for_completion_interruptible_timeout(
                        &virt_dev->cmd_completion,
                        USB_CTRL_SET_TIMEOUT);
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for %s command\n",
                                timeleft == 0 ? "Timeout" : "Signal",
                                ctx_change == 0 ?
                                        "configure endpoint" :
                                        "evaluate context");
                /* FIXME cancel the configure endpoint command */
                return -ETIME;
        }

        if (!ctx_change)
                return xhci_configure_endpoint_result(xhci, udev, virt_dev);
        return xhci_evaluate_context_result(xhci, udev, virt_dev);
}

/* Called after one or more calls to xhci_add_endpoint() or
 * xhci_drop_endpoint().  If this call fails, the USB core is expected
 * to call xhci_reset_bandwidth().
 *
 * Since we are in the middle of changing either configuration or
 * installing a new alt setting, the USB core won't allow URBs to be
 * enqueued for any endpoint on the old config or interface.  Nothing
 * else should be touching the xhci->devs[slot_id] structure, so we
 * don't need to take the xhci->lock for manipulating that.
 */
int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
        int i;
        int ret = 0;
        struct xhci_hcd *xhci;
        struct xhci_virt_device *virt_dev;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_slot_ctx *slot_ctx;

        ret = xhci_check_args(hcd, udev, NULL, 0, __func__);
        if (ret <= 0)
                return ret;
        xhci = hcd_to_xhci(hcd);

        if (!udev->slot_id || !xhci->devs || !xhci->devs[udev->slot_id]) {
                xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
                                __func__);
                return -EINVAL;
        }
        xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
        virt_dev = xhci->devs[udev->slot_id];

        /* See section 4.6.6 - A0 = 1; A1 = D0 = D1 = 0 */
        ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
        ctrl_ctx->add_flags |= SLOT_FLAG;
        ctrl_ctx->add_flags &= ~EP0_FLAG;
        ctrl_ctx->drop_flags &= ~SLOT_FLAG;
        ctrl_ctx->drop_flags &= ~EP0_FLAG;
        xhci_dbg(xhci, "New Input Control Context:\n");
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx);
        xhci_dbg_ctx(xhci, virt_dev->in_ctx,
                        LAST_CTX_TO_EP_NUM(slot_ctx->dev_info));

        ret = xhci_configure_endpoint(xhci, udev, virt_dev, false);
        if (ret) {
                /* Callee should call reset_bandwidth() */
                return ret;
        }

        xhci_dbg(xhci, "Output context after successful config ep cmd:\n");
        xhci_dbg_ctx(xhci, virt_dev->out_ctx,
                        LAST_CTX_TO_EP_NUM(slot_ctx->dev_info));

        xhci_zero_in_ctx(xhci, virt_dev);
        /* Free any old rings */
        for (i = 1; i < 31; ++i) {
                if (virt_dev->new_ep_rings[i]) {
                        xhci_ring_free(xhci, virt_dev->ep_rings[i]);
                        virt_dev->ep_rings[i] = virt_dev->new_ep_rings[i];
                        virt_dev->new_ep_rings[i] = NULL;
                }
        }

        return ret;
}

void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd *xhci;
        struct xhci_virt_device *virt_dev;
        int i, ret;

        ret = xhci_check_args(hcd, udev, NULL, 0, __func__);
        if (ret <= 0)
                return;
        xhci = hcd_to_xhci(hcd);

        if (!xhci->devs || !xhci->devs[udev->slot_id]) {
                xhci_warn(xhci, "xHCI %s called with unaddressed device\n",
                                __func__);
                return;
        }
        xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
        virt_dev = xhci->devs[udev->slot_id];
        /* Free any rings allocated for added endpoints */
        for (i = 0; i < 31; ++i) {
                if (virt_dev->new_ep_rings[i]) {
                        xhci_ring_free(xhci, virt_dev->new_ep_rings[i]);
                        virt_dev->new_ep_rings[i] = NULL;
                }
        }
        xhci_zero_in_ctx(xhci, virt_dev);
}

void xhci_setup_input_ctx_for_quirk(struct xhci_hcd *xhci,
                unsigned int slot_id, unsigned int ep_index,
                struct xhci_dequeue_state *deq_state)
{
        struct xhci_container_ctx *in_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        struct xhci_ep_ctx *ep_ctx;
        u32 added_ctxs;
        dma_addr_t addr;

        xhci_endpoint_copy(xhci, xhci->devs[slot_id], ep_index);
        in_ctx = xhci->devs[slot_id]->in_ctx;
        ep_ctx = xhci_get_ep_ctx(xhci, in_ctx, ep_index);
        addr = xhci_trb_virt_to_dma(deq_state->new_deq_seg,
                        deq_state->new_deq_ptr);
        if (addr == 0) {
                xhci_warn(xhci, "WARN Cannot submit config ep after "
                                "reset ep command\n");
                xhci_warn(xhci, "WARN deq seg = %p, deq ptr = %p\n",
                                deq_state->new_deq_seg,
                                deq_state->new_deq_ptr);
                return;
        }
        ep_ctx->deq = addr | deq_state->new_cycle_state;

        xhci_slot_copy(xhci, xhci->devs[slot_id]);

        ctrl_ctx = xhci_get_input_control_ctx(xhci, in_ctx);
        added_ctxs = xhci_get_endpoint_flag_from_index(ep_index);
        ctrl_ctx->add_flags = added_ctxs | SLOT_FLAG;
        ctrl_ctx->drop_flags = added_ctxs;

        xhci_dbg(xhci, "Slot ID %d Input Context:\n", slot_id);
        xhci_dbg_ctx(xhci, in_ctx, ep_index);
}

void xhci_cleanup_stalled_ring(struct xhci_hcd *xhci,
                struct usb_device *udev,
                unsigned int ep_index, struct xhci_ring *ep_ring)
{
        struct xhci_dequeue_state deq_state;

        xhci_dbg(xhci, "Cleaning up stalled endpoint ring\n");
        /* We need to move the HW's dequeue pointer past this TD,
         * or it will attempt to resend it on the next doorbell ring.
         */
        xhci_find_new_dequeue_state(xhci, udev->slot_id,
                        ep_index, ep_ring->stopped_td,
                        &deq_state);

        /* HW with the reset endpoint quirk will use the saved dequeue state to
         * issue a configure endpoint command later.
         */
        if (!(xhci->quirks & XHCI_RESET_EP_QUIRK)) {
                xhci_dbg(xhci, "Queueing new dequeue state\n");
                xhci_queue_new_dequeue_state(xhci, ep_ring,
                                udev->slot_id,
                                ep_index, &deq_state);
        } else {
                /* Better hope no one uses the input context between now and the
                 * reset endpoint completion!
                 */
                xhci_dbg(xhci, "Setting up input context for "
                                "configure endpoint command\n");
                xhci_setup_input_ctx_for_quirk(xhci, udev->slot_id,
                                ep_index, &deq_state);
        }
}

/* Deal with stalled endpoints.  The core should have sent the control message
 * to clear the halt condition.  However, we need to make the xHCI hardware
 * reset its sequence number, since a device will expect a sequence number of
 * zero after the halt condition is cleared.
 * Context: in_interrupt
 */
void xhci_endpoint_reset(struct usb_hcd *hcd,
                struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci;
        struct usb_device *udev;
        unsigned int ep_index;
        unsigned long flags;
        int ret;
        struct xhci_ring *ep_ring;

        xhci = hcd_to_xhci(hcd);
        udev = (struct usb_device *) ep->hcpriv;
        /* Called with a root hub endpoint (or an endpoint that wasn't added
         * with xhci_add_endpoint()
         */
        if (!ep->hcpriv)
                return;
        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ring = xhci->devs[udev->slot_id]->ep_rings[ep_index];
        if (!ep_ring->stopped_td) {
                xhci_dbg(xhci, "Endpoint 0x%x not halted, refusing to reset.\n",
                                ep->desc.bEndpointAddress);
                return;
        }
        if (usb_endpoint_xfer_control(&ep->desc)) {
                xhci_dbg(xhci, "Control endpoint stall already handled.\n");
                return;
        }

        xhci_dbg(xhci, "Queueing reset endpoint command\n");
        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_queue_reset_ep(xhci, udev->slot_id, ep_index);
        /*
         * Can't change the ring dequeue pointer until it's transitioned to the
         * stopped state, which is only upon a successful reset endpoint
         * command.  Better hope that last command worked!
         */
        if (!ret) {
                xhci_cleanup_stalled_ring(xhci, udev, ep_index, ep_ring);
                kfree(ep_ring->stopped_td);
                xhci_ring_cmd_db(xhci);
        }
        spin_unlock_irqrestore(&xhci->lock, flags);

        if (ret)
                xhci_warn(xhci, "FIXME allocate a new ring segment\n");
}

/*
 * At this point, the struct usb_device is about to go away, the device has
 * disconnected, and all traffic has been stopped and the endpoints have been
 * disabled.  Free any HC data structures associated with that device.
 */
void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        unsigned long flags;

        if (udev->slot_id == 0)
                return;

        spin_lock_irqsave(&xhci->lock, flags);
        if (xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id)) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                return;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);
        /*
         * Event command completion handler will free any data structures
         * associated with the slot.  XXX Can free sleep?
         */
}

/*
 * Returns 0 if the xHC ran out of device slots, the Enable Slot command
 * timed out, or allocating memory failed.  Returns 1 on success.
 */
int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        unsigned long flags;
        int timeleft;
        int ret;

        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_queue_slot_control(xhci, TRB_ENABLE_SLOT, 0);
        if (ret) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                return 0;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* XXX: how much time for xHC slot assignment? */
        timeleft = wait_for_completion_interruptible_timeout(&xhci->addr_dev,
                        USB_CTRL_SET_TIMEOUT);
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for a slot\n",
                                timeleft == 0 ? "Timeout" : "Signal");
                /* FIXME cancel the enable slot request */
                return 0;
        }

        if (!xhci->slot_id) {
                xhci_err(xhci, "Error while assigning device slot ID\n");
                return 0;
        }
        /* xhci_alloc_virt_device() does not touch rings; no need to lock */
        if (!xhci_alloc_virt_device(xhci, xhci->slot_id, udev, GFP_KERNEL)) {
                /* Disable slot, if we can do it without mem alloc */
                xhci_warn(xhci, "Could not allocate xHCI USB device data structures\n");
                spin_lock_irqsave(&xhci->lock, flags);
                if (!xhci_queue_slot_control(xhci, TRB_DISABLE_SLOT, udev->slot_id))
                        xhci_ring_cmd_db(xhci);
                spin_unlock_irqrestore(&xhci->lock, flags);
                return 0;
        }
        udev->slot_id = xhci->slot_id;
        /* Is this a LS or FS device under a HS hub? */
        /* Hub or peripherial? */
        return 1;
}

/*
 * Issue an Address Device command (which will issue a SetAddress request to
 * the device).
 * We should be protected by the usb_address0_mutex in khubd's hub_port_init, so
 * we should only issue and wait on one address command at the same time.
 *
 * We add one to the device address issued by the hardware because the USB core
 * uses address 1 for the root hubs (even though they're not really devices).
 */
int xhci_address_device(struct usb_hcd *hcd, struct usb_device *udev)
{
        unsigned long flags;
        int timeleft;
        struct xhci_virt_device *virt_dev;
        int ret = 0;
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_slot_ctx *slot_ctx;
        struct xhci_input_control_ctx *ctrl_ctx;
        u64 temp_64;

        if (!udev->slot_id) {
                xhci_dbg(xhci, "Bad Slot ID %d\n", udev->slot_id);
                return -EINVAL;
        }

        virt_dev = xhci->devs[udev->slot_id];

        /* If this is a Set Address to an unconfigured device, setup ep 0 */
        if (!udev->config)
                xhci_setup_addressable_virt_dev(xhci, udev);
        /* Otherwise, assume the core has the device configured how it wants */
        xhci_dbg(xhci, "Slot ID %d Input Context:\n", udev->slot_id);
        xhci_dbg_ctx(xhci, virt_dev->in_ctx, 2);

        spin_lock_irqsave(&xhci->lock, flags);
        ret = xhci_queue_address_device(xhci, virt_dev->in_ctx->dma,
                                        udev->slot_id);
        if (ret) {
                spin_unlock_irqrestore(&xhci->lock, flags);
                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
                return ret;
        }
        xhci_ring_cmd_db(xhci);
        spin_unlock_irqrestore(&xhci->lock, flags);

        /* ctrl tx can take up to 5 sec; XXX: need more time for xHC? */
        timeleft = wait_for_completion_interruptible_timeout(&xhci->addr_dev,
                        USB_CTRL_SET_TIMEOUT);
        /* FIXME: From section 4.3.4: "Software shall be responsible for timing
         * the SetAddress() "recovery interval" required by USB and aborting the
         * command on a timeout.
         */
        if (timeleft <= 0) {
                xhci_warn(xhci, "%s while waiting for a slot\n",
                                timeleft == 0 ? "Timeout" : "Signal");
                /* FIXME cancel the address device command */
                return -ETIME;
        }

        switch (virt_dev->cmd_status) {
        case COMP_CTX_STATE:
        case COMP_EBADSLT:
                xhci_err(xhci, "Setup ERROR: address device command for slot %d.\n",
                                udev->slot_id);
                ret = -EINVAL;
                break;
        case COMP_TX_ERR:
                dev_warn(&udev->dev, "Device not responding to set address.\n");
                ret = -EPROTO;
                break;
        case COMP_SUCCESS:
                xhci_dbg(xhci, "Successful Address Device command\n");
                break;
        default:
                xhci_err(xhci, "ERROR: unexpected command completion "
                                "code 0x%x.\n", virt_dev->cmd_status);
                xhci_dbg(xhci, "Slot ID %d Output Context:\n", udev->slot_id);
                xhci_dbg_ctx(xhci, virt_dev->out_ctx, 2);
                ret = -EINVAL;
                break;
        }
        if (ret) {
                return ret;
        }
        temp_64 = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
        xhci_dbg(xhci, "Op regs DCBAA ptr = %#016llx\n", temp_64);
        xhci_dbg(xhci, "Slot ID %d dcbaa entry @%p = %#016llx\n",
                        udev->slot_id,
                        &xhci->dcbaa->dev_context_ptrs[udev->slot_id],
                        (unsigned long long)
                                xhci->dcbaa->dev_context_ptrs[udev->slot_id]);
        xhci_dbg(xhci, "Output Context DMA address = %#08llx\n",
                        (unsigned long long)virt_dev->out_ctx->dma);
        xhci_dbg(xhci, "Slot ID %d Input Context:\n", udev->slot_id);
        xhci_dbg_ctx(xhci, virt_dev->in_ctx, 2);
        xhci_dbg(xhci, "Slot ID %d Output Context:\n", udev->slot_id);
        xhci_dbg_ctx(xhci, virt_dev->out_ctx, 2);
        /*
         * USB core uses address 1 for the roothubs, so we add one to the
         * address given back to us by the HC.
         */
        slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->out_ctx);
        udev->devnum = (slot_ctx->dev_state & DEV_ADDR_MASK) + 1;
        /* Zero the input context control for later use */
        ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
        ctrl_ctx->add_flags = 0;
        ctrl_ctx->drop_flags = 0;

        xhci_dbg(xhci, "Device address = %d\n", udev->devnum);
        /* XXX Meh, not sure if anyone else but choose_address uses this. */
        set_bit(udev->devnum, udev->bus->devmap.devicemap);

        return 0;
}

int xhci_get_frame(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        /* EHCI mods by the periodic size.  Why? */
        return xhci_readl(xhci, &xhci->run_regs->microframe_index) >> 3;
}

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_LICENSE("GPL");

static int __init xhci_hcd_init(void)
{
#ifdef CONFIG_PCI
        int retval = 0;

        retval = xhci_register_pci();

        if (retval < 0) {
                printk(KERN_DEBUG "Problem registering PCI driver.");
                return retval;
        }
#endif
        /*
         * Check the compiler generated sizes of structures that must be laid
         * out in specific ways for hardware access.
         */
        BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_slot_ctx) != 8*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_ep_ctx) != 8*32/8);
        /* xhci_device_control has eight fields, and also
         * embeds one xhci_slot_ctx and 31 xhci_ep_ctx
         */
        BUILD_BUG_ON(sizeof(struct xhci_stream_ctx) != 4*32/8);
        BUILD_BUG_ON(sizeof(union xhci_trb) != 4*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_erst_entry) != 4*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_cap_regs) != 7*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_intr_reg) != 8*32/8);
        /* xhci_run_regs has eight fields and embeds 128 xhci_intr_regs */
        BUILD_BUG_ON(sizeof(struct xhci_run_regs) != (8+8*128)*32/8);
        BUILD_BUG_ON(sizeof(struct xhci_doorbell_array) != 256*32/8);
        return 0;
}
module_init(xhci_hcd_init);

static void __exit xhci_hcd_cleanup(void)
{
#ifdef CONFIG_PCI
        xhci_unregister_pci();
#endif
}
module_exit(xhci_hcd_cleanup);