USB: xhci: URB cancellation support.

[linux-2.6/x86.git] / drivers / usb / host / xhci-mem.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/usb.h>
#include <linux/pci.h>

#include "xhci.h"

/*
 * Allocates a generic ring segment from the ring pool, sets the dma address,
 * initializes the segment to zero, and sets the private next pointer to NULL.
 *
 * Section 4.11.1.1:
 * "All components of all Command and Transfer TRBs shall be initialized to '0'"
 */
static struct xhci_segment *xhci_segment_alloc(struct xhci_hcd *xhci, gfp_t flags)
{
        struct xhci_segment *seg;
        dma_addr_t      dma;

        seg = kzalloc(sizeof *seg, flags);
        if (!seg)
                return 0;
        xhci_dbg(xhci, "Allocating priv segment structure at 0x%x\n",
                        (unsigned int) seg);

        seg->trbs = dma_pool_alloc(xhci->segment_pool, flags, &dma);
        if (!seg->trbs) {
                kfree(seg);
                return 0;
        }
        xhci_dbg(xhci, "// Allocating segment at 0x%x (virtual) 0x%x (DMA)\n",
                        (unsigned int) seg->trbs, (u32) dma);

        memset(seg->trbs, 0, SEGMENT_SIZE);
        seg->dma = dma;
        seg->next = NULL;

        return seg;
}

static void xhci_segment_free(struct xhci_hcd *xhci, struct xhci_segment *seg)
{
        if (!seg)
                return;
        if (seg->trbs) {
                xhci_dbg(xhci, "Freeing DMA segment at 0x%x"
                                " (virtual) 0x%x (DMA)\n",
                                (unsigned int) seg->trbs, (u32) seg->dma);
                dma_pool_free(xhci->segment_pool, seg->trbs, seg->dma);
                seg->trbs = NULL;
        }
        xhci_dbg(xhci, "Freeing priv segment structure at 0x%x\n",
                        (unsigned int) seg);
        kfree(seg);
}

/*
 * Make the prev segment point to the next segment.
 *
 * Change the last TRB in the prev segment to be a Link TRB which points to the
 * DMA address of the next segment.  The caller needs to set any Link TRB
 * related flags, such as End TRB, Toggle Cycle, and no snoop.
 */
static void xhci_link_segments(struct xhci_hcd *xhci, struct xhci_segment *prev,
                struct xhci_segment *next, bool link_trbs)
{
        u32 val;

        if (!prev || !next)
                return;
        prev->next = next;
        if (link_trbs) {
                prev->trbs[TRBS_PER_SEGMENT-1].link.segment_ptr[0] = next->dma;

                /* Set the last TRB in the segment to have a TRB type ID of Link TRB */
                val = prev->trbs[TRBS_PER_SEGMENT-1].link.control;
                val &= ~TRB_TYPE_BITMASK;
                val |= TRB_TYPE(TRB_LINK);
                prev->trbs[TRBS_PER_SEGMENT-1].link.control = val;
        }
        xhci_dbg(xhci, "Linking segment 0x%x to segment 0x%x (DMA)\n",
                        prev->dma, next->dma);
}

/* XXX: Do we need the hcd structure in all these functions? */
void xhci_ring_free(struct xhci_hcd *xhci, struct xhci_ring *ring)
{
        struct xhci_segment *seg;
        struct xhci_segment *first_seg;

        if (!ring || !ring->first_seg)
                return;
        first_seg = ring->first_seg;
        seg = first_seg->next;
        xhci_dbg(xhci, "Freeing ring at 0x%x\n", (unsigned int) ring);
        while (seg != first_seg) {
                struct xhci_segment *next = seg->next;
                xhci_segment_free(xhci, seg);
                seg = next;
        }
        xhci_segment_free(xhci, first_seg);
        ring->first_seg = NULL;
        kfree(ring);
}

/**
 * Create a new ring with zero or more segments.
 *
 * Link each segment together into a ring.
 * Set the end flag and the cycle toggle bit on the last segment.
 * See section 4.9.1 and figures 15 and 16.
 */
static struct xhci_ring *xhci_ring_alloc(struct xhci_hcd *xhci,
                unsigned int num_segs, bool link_trbs, gfp_t flags)
{
        struct xhci_ring        *ring;
        struct xhci_segment     *prev;

        ring = kzalloc(sizeof *(ring), flags);
        xhci_dbg(xhci, "Allocating ring at 0x%x\n", (unsigned int) ring);
        if (!ring)
                return 0;

        INIT_LIST_HEAD(&ring->td_list);
        INIT_LIST_HEAD(&ring->cancelled_td_list);
        if (num_segs == 0)
                return ring;

        ring->first_seg = xhci_segment_alloc(xhci, flags);
        if (!ring->first_seg)
                goto fail;
        num_segs--;

        prev = ring->first_seg;
        while (num_segs > 0) {
                struct xhci_segment     *next;

                next = xhci_segment_alloc(xhci, flags);
                if (!next)
                        goto fail;
                xhci_link_segments(xhci, prev, next, link_trbs);

                prev = next;
                num_segs--;
        }
        xhci_link_segments(xhci, prev, ring->first_seg, link_trbs);

        if (link_trbs) {
                /* See section 4.9.2.1 and 6.4.4.1 */
                prev->trbs[TRBS_PER_SEGMENT-1].link.control |= (LINK_TOGGLE);
                xhci_dbg(xhci, "Wrote link toggle flag to"
                                " segment 0x%x (virtual), 0x%x (DMA)\n",
                                (unsigned int) prev, (u32) prev->dma);
        }
        /* The ring is empty, so the enqueue pointer == dequeue pointer */
        ring->enqueue = ring->first_seg->trbs;
        ring->enq_seg = ring->first_seg;
        ring->dequeue = ring->enqueue;
        ring->deq_seg = ring->first_seg;
        /* The ring is initialized to 0. The producer must write 1 to the cycle
         * bit to handover ownership of the TRB, so PCS = 1.  The consumer must
         * compare CCS to the cycle bit to check ownership, so CCS = 1.
         */
        ring->cycle_state = 1;

        return ring;

fail:
        xhci_ring_free(xhci, ring);
        return 0;
}

/* All the xhci_tds in the ring's TD list should be freed at this point */
void xhci_free_virt_device(struct xhci_hcd *xhci, int slot_id)
{
        struct xhci_virt_device *dev;
        int i;

        /* Slot ID 0 is reserved */
        if (slot_id == 0 || !xhci->devs[slot_id])
                return;

        dev = xhci->devs[slot_id];
        xhci->dcbaa->dev_context_ptrs[2*slot_id] = 0;
        xhci->dcbaa->dev_context_ptrs[2*slot_id + 1] = 0;
        if (!dev)
                return;

        for (i = 0; i < 31; ++i)
                if (dev->ep_rings[i])
                        xhci_ring_free(xhci, dev->ep_rings[i]);

        if (dev->in_ctx)
                dma_pool_free(xhci->device_pool,
                                dev->in_ctx, dev->in_ctx_dma);
        if (dev->out_ctx)
                dma_pool_free(xhci->device_pool,
                                dev->out_ctx, dev->out_ctx_dma);
        kfree(xhci->devs[slot_id]);
        xhci->devs[slot_id] = 0;
}

int xhci_alloc_virt_device(struct xhci_hcd *xhci, int slot_id,
                struct usb_device *udev, gfp_t flags)
{
        dma_addr_t      dma;
        struct xhci_virt_device *dev;

        /* Slot ID 0 is reserved */
        if (slot_id == 0 || xhci->devs[slot_id]) {
                xhci_warn(xhci, "Bad Slot ID %d\n", slot_id);
                return 0;
        }

        xhci->devs[slot_id] = kzalloc(sizeof(*xhci->devs[slot_id]), flags);
        if (!xhci->devs[slot_id])
                return 0;
        dev = xhci->devs[slot_id];

        /* Allocate the (output) device context that will be used in the HC */
        dev->out_ctx = dma_pool_alloc(xhci->device_pool, flags, &dma);
        if (!dev->out_ctx)
                goto fail;
        dev->out_ctx_dma = dma;
        xhci_dbg(xhci, "Slot %d output ctx = 0x%x (dma)\n", slot_id, dma);
        memset(dev->out_ctx, 0, sizeof(*dev->out_ctx));

        /* Allocate the (input) device context for address device command */
        dev->in_ctx = dma_pool_alloc(xhci->device_pool, flags, &dma);
        if (!dev->in_ctx)
                goto fail;
        dev->in_ctx_dma = dma;
        xhci_dbg(xhci, "Slot %d input ctx = 0x%x (dma)\n", slot_id, dma);
        memset(dev->in_ctx, 0, sizeof(*dev->in_ctx));

        /* Allocate endpoint 0 ring */
        dev->ep_rings[0] = xhci_ring_alloc(xhci, 1, true, flags);
        if (!dev->ep_rings[0])
                goto fail;

        init_completion(&dev->cmd_completion);

        /*
         * Point to output device context in dcbaa; skip the output control
         * context, which is eight 32 bit fields (or 32 bytes long)
         */
        xhci->dcbaa->dev_context_ptrs[2*slot_id] =
                (u32) dev->out_ctx_dma + (32);
        xhci_dbg(xhci, "Set slot id %d dcbaa entry 0x%x to 0x%x\n",
                        slot_id,
                        (unsigned int) &xhci->dcbaa->dev_context_ptrs[2*slot_id],
                        dev->out_ctx_dma);
        xhci->dcbaa->dev_context_ptrs[2*slot_id + 1] = 0;

        return 1;
fail:
        xhci_free_virt_device(xhci, slot_id);
        return 0;
}

/* Setup an xHCI virtual device for a Set Address command */
int xhci_setup_addressable_virt_dev(struct xhci_hcd *xhci, struct usb_device *udev)
{
        struct xhci_virt_device *dev;
        struct xhci_ep_ctx      *ep0_ctx;
        struct usb_device       *top_dev;

        dev = xhci->devs[udev->slot_id];
        /* Slot ID 0 is reserved */
        if (udev->slot_id == 0 || !dev) {
                xhci_warn(xhci, "Slot ID %d is not assigned to this device\n",
                                udev->slot_id);
                return -EINVAL;
        }
        ep0_ctx = &dev->in_ctx->ep[0];

        /* 2) New slot context and endpoint 0 context are valid*/
        dev->in_ctx->add_flags = SLOT_FLAG | EP0_FLAG;

        /* 3) Only the control endpoint is valid - one endpoint context */
        dev->in_ctx->slot.dev_info |= LAST_CTX(1);

        switch (udev->speed) {
        case USB_SPEED_SUPER:
                dev->in_ctx->slot.dev_info |= (u32) udev->route;
                dev->in_ctx->slot.dev_info |= (u32) SLOT_SPEED_SS;
                break;
        case USB_SPEED_HIGH:
                dev->in_ctx->slot.dev_info |= (u32) SLOT_SPEED_HS;
                break;
        case USB_SPEED_FULL:
                dev->in_ctx->slot.dev_info |= (u32) SLOT_SPEED_FS;
                break;
        case USB_SPEED_LOW:
                dev->in_ctx->slot.dev_info |= (u32) SLOT_SPEED_LS;
                break;
        case USB_SPEED_VARIABLE:
                xhci_dbg(xhci, "FIXME xHCI doesn't support wireless speeds\n");
                return -EINVAL;
                break;
        default:
                /* Speed was set earlier, this shouldn't happen. */
                BUG();
        }
        /* Find the root hub port this device is under */
        for (top_dev = udev; top_dev->parent && top_dev->parent->parent;
                        top_dev = top_dev->parent)
                /* Found device below root hub */;
        dev->in_ctx->slot.dev_info2 |= (u32) ROOT_HUB_PORT(top_dev->portnum);
        xhci_dbg(xhci, "Set root hub portnum to %d\n", top_dev->portnum);

        /* Is this a LS/FS device under a HS hub? */
        /*
         * FIXME: I don't think this is right, where does the TT info for the
         * roothub or parent hub come from?
         */
        if ((udev->speed == USB_SPEED_LOW || udev->speed == USB_SPEED_FULL) &&
                        udev->tt) {
                dev->in_ctx->slot.tt_info = udev->tt->hub->slot_id;
                dev->in_ctx->slot.tt_info |= udev->ttport << 8;
        }
        xhci_dbg(xhci, "udev->tt = 0x%x\n", (unsigned int) udev->tt);
        xhci_dbg(xhci, "udev->ttport = 0x%x\n", udev->ttport);

        /* Step 4 - ring already allocated */
        /* Step 5 */
        ep0_ctx->ep_info2 = EP_TYPE(CTRL_EP);
        /*
         * See section 4.3 bullet 6:
         * The default Max Packet size for ep0 is "8 bytes for a USB2
         * LS/FS/HS device or 512 bytes for a USB3 SS device"
         * XXX: Not sure about wireless USB devices.
         */
        if (udev->speed == USB_SPEED_SUPER)
                ep0_ctx->ep_info2 |= MAX_PACKET(512);
        else
                ep0_ctx->ep_info2 |= MAX_PACKET(8);
        /* EP 0 can handle "burst" sizes of 1, so Max Burst Size field is 0 */
        ep0_ctx->ep_info2 |= MAX_BURST(0);
        ep0_ctx->ep_info2 |= ERROR_COUNT(3);

        ep0_ctx->deq[0] =
                dev->ep_rings[0]->first_seg->dma;
        ep0_ctx->deq[0] |= dev->ep_rings[0]->cycle_state;
        ep0_ctx->deq[1] = 0;

        /* Steps 7 and 8 were done in xhci_alloc_virt_device() */

        return 0;
}

/* Return the polling or NAK interval.
 *
 * The polling interval is expressed in "microframes".  If xHCI's Interval field
 * is set to N, it will service the endpoint every 2^(Interval)*125us.
 *
 * The NAK interval is one NAK per 1 to 255 microframes, or no NAKs if interval
 * is set to 0.
 */
static inline unsigned int xhci_get_endpoint_interval(struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        unsigned int interval = 0;

        switch (udev->speed) {
        case USB_SPEED_HIGH:
                /* Max NAK rate */
                if (usb_endpoint_xfer_control(&ep->desc) ||
                                usb_endpoint_xfer_bulk(&ep->desc))
                        interval = ep->desc.bInterval;
                /* Fall through - SS and HS isoc/int have same decoding */
        case USB_SPEED_SUPER:
                if (usb_endpoint_xfer_int(&ep->desc) ||
                                usb_endpoint_xfer_isoc(&ep->desc)) {
                        if (ep->desc.bInterval == 0)
                                interval = 0;
                        else
                                interval = ep->desc.bInterval - 1;
                        if (interval > 15)
                                interval = 15;
                        if (interval != ep->desc.bInterval + 1)
                                dev_warn(&udev->dev, "ep %#x - rounding interval to %d microframes\n",
                                                ep->desc.bEndpointAddress, 1 << interval);
                }
                break;
        /* Convert bInterval (in 1-255 frames) to microframes and round down to
         * nearest power of 2.
         */
        case USB_SPEED_FULL:
        case USB_SPEED_LOW:
                if (usb_endpoint_xfer_int(&ep->desc) ||
                                usb_endpoint_xfer_isoc(&ep->desc)) {
                        interval = fls(8*ep->desc.bInterval) - 1;
                        if (interval > 10)
                                interval = 10;
                        if (interval < 3)
                                interval = 3;
                        if ((1 << interval) != 8*ep->desc.bInterval)
                                dev_warn(&udev->dev, "ep %#x - rounding interval to %d microframes\n",
                                                ep->desc.bEndpointAddress, 1 << interval);
                }
                break;
        default:
                BUG();
        }
        return EP_INTERVAL(interval);
}

static inline u32 xhci_get_endpoint_type(struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        int in;
        u32 type;

        in = usb_endpoint_dir_in(&ep->desc);
        if (usb_endpoint_xfer_control(&ep->desc)) {
                type = EP_TYPE(CTRL_EP);
        } else if (usb_endpoint_xfer_bulk(&ep->desc)) {
                if (in)
                        type = EP_TYPE(BULK_IN_EP);
                else
                        type = EP_TYPE(BULK_OUT_EP);
        } else if (usb_endpoint_xfer_isoc(&ep->desc)) {
                if (in)
                        type = EP_TYPE(ISOC_IN_EP);
                else
                        type = EP_TYPE(ISOC_OUT_EP);
        } else if (usb_endpoint_xfer_int(&ep->desc)) {
                if (in)
                        type = EP_TYPE(INT_IN_EP);
                else
                        type = EP_TYPE(INT_OUT_EP);
        } else {
                BUG();
        }
        return type;
}

int xhci_endpoint_init(struct xhci_hcd *xhci,
                struct xhci_virt_device *virt_dev,
                struct usb_device *udev,
                struct usb_host_endpoint *ep)
{
        unsigned int ep_index;
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_ring *ep_ring;
        unsigned int max_packet;
        unsigned int max_burst;

        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = &virt_dev->in_ctx->ep[ep_index];

        /* Set up the endpoint ring */
        virt_dev->new_ep_rings[ep_index] = xhci_ring_alloc(xhci, 1, true, GFP_KERNEL);
        if (!virt_dev->new_ep_rings[ep_index])
                return -ENOMEM;
        ep_ring = virt_dev->new_ep_rings[ep_index];
        ep_ctx->deq[1] = 0;
        ep_ctx->deq[0] = ep_ring->first_seg->dma | ep_ring->cycle_state;

        ep_ctx->ep_info = xhci_get_endpoint_interval(udev, ep);

        /* FIXME dig Mult and streams info out of ep companion desc */

        /* Allow 3 retries for everything but isoc */
        if (!usb_endpoint_xfer_isoc(&ep->desc))
                ep_ctx->ep_info2 = ERROR_COUNT(3);
        else
                ep_ctx->ep_info2 = ERROR_COUNT(0);

        ep_ctx->ep_info2 |= xhci_get_endpoint_type(udev, ep);

        /* Set the max packet size and max burst */
        switch (udev->speed) {
        case USB_SPEED_SUPER:
                max_packet = ep->desc.wMaxPacketSize;
                ep_ctx->ep_info2 |= MAX_PACKET(max_packet);
                /* dig out max burst from ep companion desc */
                max_packet = ep->ep_comp->desc.bMaxBurst;
                ep_ctx->ep_info2 |= MAX_BURST(max_packet);
                break;
        case USB_SPEED_HIGH:
                /* bits 11:12 specify the number of additional transaction
                 * opportunities per microframe (USB 2.0, section 9.6.6)
                 */
                if (usb_endpoint_xfer_isoc(&ep->desc) ||
                                usb_endpoint_xfer_int(&ep->desc)) {
                        max_burst = (ep->desc.wMaxPacketSize & 0x1800) >> 11;
                        ep_ctx->ep_info2 |= MAX_BURST(max_burst);
                }
                /* Fall through */
        case USB_SPEED_FULL:
        case USB_SPEED_LOW:
                max_packet = ep->desc.wMaxPacketSize & 0x3ff;
                ep_ctx->ep_info2 |= MAX_PACKET(max_packet);
                break;
        default:
                BUG();
        }
        /* FIXME Debug endpoint context */
        return 0;
}

void xhci_endpoint_zero(struct xhci_hcd *xhci,
                struct xhci_virt_device *virt_dev,
                struct usb_host_endpoint *ep)
{
        unsigned int ep_index;
        struct xhci_ep_ctx *ep_ctx;

        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = &virt_dev->in_ctx->ep[ep_index];

        ep_ctx->ep_info = 0;
        ep_ctx->ep_info2 = 0;
        ep_ctx->deq[1] = 0;
        ep_ctx->deq[0] = 0;
        ep_ctx->tx_info = 0;
        /* Don't free the endpoint ring until the set interface or configuration
         * request succeeds.
         */
}

void xhci_mem_cleanup(struct xhci_hcd *xhci)
{
        struct pci_dev  *pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
        int size;
        int i;

        /* Free the Event Ring Segment Table and the actual Event Ring */
        xhci_writel(xhci, 0, &xhci->ir_set->erst_size);
        xhci_writel(xhci, 0, &xhci->ir_set->erst_base[1]);
        xhci_writel(xhci, 0, &xhci->ir_set->erst_base[0]);
        xhci_writel(xhci, 0, &xhci->ir_set->erst_dequeue[1]);
        xhci_writel(xhci, 0, &xhci->ir_set->erst_dequeue[0]);
        size = sizeof(struct xhci_erst_entry)*(xhci->erst.num_entries);
        if (xhci->erst.entries)
                pci_free_consistent(pdev, size,
                                xhci->erst.entries, xhci->erst.erst_dma_addr);
        xhci->erst.entries = NULL;
        xhci_dbg(xhci, "Freed ERST\n");
        if (xhci->event_ring)
                xhci_ring_free(xhci, xhci->event_ring);
        xhci->event_ring = NULL;
        xhci_dbg(xhci, "Freed event ring\n");

        xhci_writel(xhci, 0, &xhci->op_regs->cmd_ring[1]);
        xhci_writel(xhci, 0, &xhci->op_regs->cmd_ring[0]);
        if (xhci->cmd_ring)
                xhci_ring_free(xhci, xhci->cmd_ring);
        xhci->cmd_ring = NULL;
        xhci_dbg(xhci, "Freed command ring\n");

        for (i = 1; i < MAX_HC_SLOTS; ++i)
                xhci_free_virt_device(xhci, i);

        if (xhci->segment_pool)
                dma_pool_destroy(xhci->segment_pool);
        xhci->segment_pool = NULL;
        xhci_dbg(xhci, "Freed segment pool\n");

        if (xhci->device_pool)
                dma_pool_destroy(xhci->device_pool);
        xhci->device_pool = NULL;
        xhci_dbg(xhci, "Freed device context pool\n");

        xhci_writel(xhci, 0, &xhci->op_regs->dcbaa_ptr[1]);
        xhci_writel(xhci, 0, &xhci->op_regs->dcbaa_ptr[0]);
        if (xhci->dcbaa)
                pci_free_consistent(pdev, sizeof(*xhci->dcbaa),
                                xhci->dcbaa, xhci->dcbaa->dma);
        xhci->dcbaa = NULL;

        xhci->page_size = 0;
        xhci->page_shift = 0;
}

int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
{
        dma_addr_t      dma;
        struct device   *dev = xhci_to_hcd(xhci)->self.controller;
        unsigned int    val, val2;
        struct xhci_segment     *seg;
        u32 page_size;
        int i;

        page_size = xhci_readl(xhci, &xhci->op_regs->page_size);
        xhci_dbg(xhci, "Supported page size register = 0x%x\n", page_size);
        for (i = 0; i < 16; i++) {
                if ((0x1 & page_size) != 0)
                        break;
                page_size = page_size >> 1;
        }
        if (i < 16)
                xhci_dbg(xhci, "Supported page size of %iK\n", (1 << (i+12)) / 1024);
        else
                xhci_warn(xhci, "WARN: no supported page size\n");
        /* Use 4K pages, since that's common and the minimum the HC supports */
        xhci->page_shift = 12;
        xhci->page_size = 1 << xhci->page_shift;
        xhci_dbg(xhci, "HCD page size set to %iK\n", xhci->page_size / 1024);

        /*
         * Program the Number of Device Slots Enabled field in the CONFIG
         * register with the max value of slots the HC can handle.
         */
        val = HCS_MAX_SLOTS(xhci_readl(xhci, &xhci->cap_regs->hcs_params1));
        xhci_dbg(xhci, "// xHC can handle at most %d device slots.\n",
                        (unsigned int) val);
        val2 = xhci_readl(xhci, &xhci->op_regs->config_reg);
        val |= (val2 & ~HCS_SLOTS_MASK);
        xhci_dbg(xhci, "// Setting Max device slots reg = 0x%x.\n",
                        (unsigned int) val);
        xhci_writel(xhci, val, &xhci->op_regs->config_reg);

        /*
         * Section 5.4.8 - doorbell array must be
         * "physically contiguous and 64-byte (cache line) aligned".
         */
        xhci->dcbaa = pci_alloc_consistent(to_pci_dev(dev),
                        sizeof(*xhci->dcbaa), &dma);
        if (!xhci->dcbaa)
                goto fail;
        memset(xhci->dcbaa, 0, sizeof *(xhci->dcbaa));
        xhci->dcbaa->dma = dma;
        xhci_dbg(xhci, "// Device context base array address = 0x%x (DMA), 0x%x (virt)\n",
                        xhci->dcbaa->dma, (unsigned int) xhci->dcbaa);
        xhci_writel(xhci, (u32) 0, &xhci->op_regs->dcbaa_ptr[1]);
        xhci_writel(xhci, dma, &xhci->op_regs->dcbaa_ptr[0]);

        /*
         * Initialize the ring segment pool.  The ring must be a contiguous
         * structure comprised of TRBs.  The TRBs must be 16 byte aligned,
         * however, the command ring segment needs 64-byte aligned segments,
         * so we pick the greater alignment need.
         */
        xhci->segment_pool = dma_pool_create("xHCI ring segments", dev,
                        SEGMENT_SIZE, 64, xhci->page_size);
        /* See Table 46 and Note on Figure 55 */
        /* FIXME support 64-byte contexts */
        xhci->device_pool = dma_pool_create("xHCI input/output contexts", dev,
                        sizeof(struct xhci_device_control),
                        64, xhci->page_size);
        if (!xhci->segment_pool || !xhci->device_pool)
                goto fail;

        /* Set up the command ring to have one segments for now. */
        xhci->cmd_ring = xhci_ring_alloc(xhci, 1, true, flags);
        if (!xhci->cmd_ring)
                goto fail;
        xhci_dbg(xhci, "Allocated command ring at 0x%x\n", (unsigned int) xhci->cmd_ring);
        xhci_dbg(xhci, "First segment DMA is 0x%x\n", (unsigned int) xhci->cmd_ring->first_seg->dma);

        /* Set the address in the Command Ring Control register */
        val = xhci_readl(xhci, &xhci->op_regs->cmd_ring[0]);
        val = (val & ~CMD_RING_ADDR_MASK) |
                (xhci->cmd_ring->first_seg->dma & CMD_RING_ADDR_MASK) |
                xhci->cmd_ring->cycle_state;
        xhci_dbg(xhci, "// Setting command ring address high bits to 0x0\n");
        xhci_writel(xhci, (u32) 0, &xhci->op_regs->cmd_ring[1]);
        xhci_dbg(xhci, "// Setting command ring address low bits to 0x%x\n", val);
        xhci_writel(xhci, val, &xhci->op_regs->cmd_ring[0]);
        xhci_dbg_cmd_ptrs(xhci);

        val = xhci_readl(xhci, &xhci->cap_regs->db_off);
        val &= DBOFF_MASK;
        xhci_dbg(xhci, "// Doorbell array is located at offset 0x%x"
                        " from cap regs base addr\n", val);
        xhci->dba = (void *) xhci->cap_regs + val;
        xhci_dbg_regs(xhci);
        xhci_print_run_regs(xhci);
        /* Set ir_set to interrupt register set 0 */
        xhci->ir_set = (void *) xhci->run_regs->ir_set;

        /*
         * Event ring setup: Allocate a normal ring, but also setup
         * the event ring segment table (ERST).  Section 4.9.3.
         */
        xhci_dbg(xhci, "// Allocating event ring\n");
        xhci->event_ring = xhci_ring_alloc(xhci, ERST_NUM_SEGS, false, flags);
        if (!xhci->event_ring)
                goto fail;

        xhci->erst.entries = pci_alloc_consistent(to_pci_dev(dev),
                        sizeof(struct xhci_erst_entry)*ERST_NUM_SEGS, &dma);
        if (!xhci->erst.entries)
                goto fail;
        xhci_dbg(xhci, "// Allocated event ring segment table at 0x%x\n", dma);

        memset(xhci->erst.entries, 0, sizeof(struct xhci_erst_entry)*ERST_NUM_SEGS);
        xhci->erst.num_entries = ERST_NUM_SEGS;
        xhci->erst.erst_dma_addr = dma;
        xhci_dbg(xhci, "Set ERST to 0; private num segs = %i, virt addr = 0x%x, dma addr = 0x%x\n",
                        xhci->erst.num_entries,
                        (unsigned int) xhci->erst.entries,
                        xhci->erst.erst_dma_addr);

        /* set ring base address and size for each segment table entry */
        for (val = 0, seg = xhci->event_ring->first_seg; val < ERST_NUM_SEGS; val++) {
                struct xhci_erst_entry *entry = &xhci->erst.entries[val];
                entry->seg_addr[1] = 0;
                entry->seg_addr[0] = seg->dma;
                entry->seg_size = TRBS_PER_SEGMENT;
                entry->rsvd = 0;
                seg = seg->next;
        }

        /* set ERST count with the number of entries in the segment table */
        val = xhci_readl(xhci, &xhci->ir_set->erst_size);
        val &= ERST_SIZE_MASK;
        val |= ERST_NUM_SEGS;
        xhci_dbg(xhci, "// Write ERST size = %i to ir_set 0 (some bits preserved)\n",
                        val);
        xhci_writel(xhci, val, &xhci->ir_set->erst_size);

        xhci_dbg(xhci, "// Set ERST entries to point to event ring.\n");
        /* set the segment table base address */
        xhci_dbg(xhci, "// Set ERST base address for ir_set 0 = 0x%x\n",
                        xhci->erst.erst_dma_addr);
        xhci_writel(xhci, 0, &xhci->ir_set->erst_base[1]);
        val = xhci_readl(xhci, &xhci->ir_set->erst_base[0]);
        val &= ERST_PTR_MASK;
        val |= (xhci->erst.erst_dma_addr & ~ERST_PTR_MASK);
        xhci_writel(xhci, val, &xhci->ir_set->erst_base[0]);

        /* Set the event ring dequeue address */
        set_hc_event_deq(xhci);
        xhci_dbg(xhci, "Wrote ERST address to ir_set 0.\n");
        xhci_print_ir_set(xhci, xhci->ir_set, 0);

        /*
         * XXX: Might need to set the Interrupter Moderation Register to
         * something other than the default (~1ms minimum between interrupts).
         * See section 5.5.1.2.
         */
        init_completion(&xhci->addr_dev);
        for (i = 0; i < MAX_HC_SLOTS; ++i)
                xhci->devs[i] = 0;

        return 0;
fail:
        xhci_warn(xhci, "Couldn't initialize memory\n");
        xhci_mem_cleanup(xhci);
        return -ENOMEM;
}