/*
 * 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 <linux/dmapool.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 %p\n", seg);

	seg->trbs = dma_pool_alloc(xhci->segment_pool, flags, &dma);
	if (!seg->trbs) {
		kfree(seg);
		return 0;
	}
	xhci_dbg(xhci, "// Allocating segment at %p (virtual) 0x%llx (DMA)\n",
			seg->trbs, (unsigned long long)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 %p (virtual) 0x%llx (DMA)\n",
				seg->trbs, (unsigned long long)seg->dma);
		dma_pool_free(xhci->segment_pool, seg->trbs, seg->dma);
		seg->trbs = NULL;
	}
	xhci_dbg(xhci, "Freeing priv segment structure at %p\n", 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%llx to segment 0x%llx (DMA)\n",
			(unsigned long long)prev->dma,
			(unsigned long long)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 %p\n", 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 %p\n", 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 %p (virtual), 0x%llx (DMA)\n",
				prev, (unsigned long long)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%llx (dma)\n", slot_id,
			(unsigned long long)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%llx (dma)\n", slot_id,
			(unsigned long long)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 %p to 0x%llx\n",
			slot_id,
			&xhci->dcbaa->dev_context_ptrs[2*slot_id],
			(unsigned long long)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 = %p\n", 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,
		gfp_t mem_flags)
{
	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, mem_flags);
	if (!virt_dev->new_ep_rings[ep_index])
		return -ENOMEM;
	ep_ring = virt_dev->new_ep_rings[ep_index];
	ep_ctx->deq[0] = ep_ring->first_seg->dma | ep_ring->cycle_state;
	ep_ctx->deq[1] = 0;

	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->ss_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[0] = 0;
	ep_ctx->deq[1] = 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[0]);
	xhci_writel(xhci, 0, &xhci->ir_set->erst_base[1]);
	xhci_writel(xhci, 0, &xhci->ir_set->erst_dequeue[0]);
	xhci_writel(xhci, 0, &xhci->ir_set->erst_dequeue[1]);
	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[0]);
	xhci_writel(xhci, 0, &xhci->op_regs->cmd_ring[1]);
	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[0]);
	xhci_writel(xhci, 0, &xhci->op_regs->dcbaa_ptr[1]);
	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%llx (DMA), %p (virt)\n",
			(unsigned long long)xhci->dcbaa->dma, xhci->dcbaa);
	xhci_writel(xhci, dma, &xhci->op_regs->dcbaa_ptr[0]);
	xhci_writel(xhci, (u32) 0, &xhci->op_regs->dcbaa_ptr[1]);

	/*
	 * 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 %p\n", xhci->cmd_ring);
	xhci_dbg(xhci, "First segment DMA is 0x%llx\n",
			(unsigned long long)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 low bits to 0x%x\n", val);
	xhci_writel(xhci, val, &xhci->op_regs->cmd_ring[0]);
	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_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%llx\n",
			(unsigned long long)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 = %p, dma addr = 0x%llx\n",
			xhci->erst.num_entries,
			xhci->erst.entries,
			(unsigned long long)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[0] = seg->dma;
		entry->seg_addr[1] = 0;
		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%llx\n",
			(unsigned long long)xhci->erst.erst_dma_addr);
	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]);
	xhci_writel(xhci, 0, &xhci->ir_set->erst_base[1]);

	/* Set the event ring dequeue address */
	xhci_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;
}