// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <ddk/debug.h>
#include <zircon/hw/usb.h>
#include <zircon/hw/usb-hub.h>
#include <endian.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <threads.h>

#include "xhci-device-manager.h"
#include "xhci-root-hub.h"
#include "xhci-transfer-common.h"
#include "xhci-util.h"

// list of devices pending result of enable slot command
// list is kept on xhci_t.command_queue
typedef struct {
    enum {
        ENUMERATE_DEVICE,
        DISCONNECT_DEVICE,
        START_ROOT_HUBS,
        STOP_THREAD,
    } command;
    list_node_t node;
    uint32_t hub_address;
    uint32_t port;
    usb_speed_t speed;
} xhci_device_command_t;

static uint32_t xhci_get_route_string(xhci_t* xhci, uint32_t hub_address, uint32_t port) {
    if (hub_address == 0) {
        return 0;
    }

    xhci_slot_t* hub_slot = &xhci->slots[hub_address];
    uint32_t route = XHCI_GET_BITS32(&hub_slot->sc->sc0, SLOT_CTX_ROUTE_STRING_START,
                                     SLOT_CTX_ROUTE_STRING_BITS);
    int shift = 0;
    while (shift < 20) {
        if ((route & (0xF << shift)) == 0) {
            // reached end of parent hub's route string
            route |= ((port & 0xF) << shift);
            break;
        }
        shift += 4;
    }
    return route;
}

static zx_status_t xhci_address_device(xhci_t* xhci, uint32_t slot_id, uint32_t hub_address,
                                       uint32_t port, usb_speed_t speed) {
    zxlogf(TRACE, "xhci_address_device slot_id: %d port: %d hub_address: %d speed: %d\n",
            slot_id, port, hub_address, speed);

    int rh_index = xhci_get_root_hub_index(xhci, hub_address);
    if (rh_index >= 0) {
        // For virtual root hub devices, real hub_address is 0
        hub_address = 0;
        // convert virtual root hub port number to real port number
        port = xhci->root_hubs[rh_index].port_map[port - 1] + 1;
    }

    xhci_slot_t* slot = &xhci->slots[slot_id];
    if (slot->sc)
        return ZX_ERR_BAD_STATE;
    slot->hub_address = hub_address;
    slot->port = port;
    slot->rh_port = (hub_address == 0 ? port : xhci->slots[hub_address].rh_port);
    slot->speed = speed;

    // allocate a read-only DMA buffer for device context
    size_t dc_length = xhci->context_size * XHCI_NUM_EPS;
    zx_status_t status = io_buffer_init(&slot->buffer, xhci->bti_handle, dc_length,
                                        IO_BUFFER_RO | IO_BUFFER_CONTIG | XHCI_IO_BUFFER_UNCACHED);
    if (status != ZX_OK) {
        zxlogf(ERROR, "xhci_address_device: failed to allocate io_buffer for slot\n");
        return status;
    }
    uint8_t* device_context = (uint8_t *)io_buffer_virt(&slot->buffer);
    xhci_endpoint_t* ep = &slot->eps[0];
    status = xhci_transfer_ring_init(&ep->transfer_ring, xhci->bti_handle, TRANSFER_RING_SIZE);
    if (status < 0) return status;
    ep->transfer_state = calloc(1, sizeof(xhci_transfer_state_t));
    if (!ep->transfer_state) {
        return ZX_ERR_NO_MEMORY;
    }
    xhci_transfer_ring_t* transfer_ring = &ep->transfer_ring;
    ep->ep_type = USB_ENDPOINT_CONTROL;

    mtx_lock(&xhci->input_context_lock);
    xhci_input_control_context_t* icc = (xhci_input_control_context_t*)xhci->input_context;
    zx_paddr_t icc_phys = xhci->input_context_phys;
    xhci_slot_context_t* sc = (xhci_slot_context_t*)&xhci->input_context[1 * xhci->context_size];
    xhci_endpoint_context_t* ep0c = (xhci_endpoint_context_t*)&xhci->input_context[2 * xhci->context_size];
    memset((void*)icc, 0, xhci->context_size);
    memset((void*)sc, 0, xhci->context_size);
    memset((void*)ep0c, 0, xhci->context_size);

    slot->sc = (xhci_slot_context_t*)device_context;
    device_context += xhci->context_size;
    for (int i = 0; i < XHCI_NUM_EPS; i++) {
        slot->eps[i].epc = (xhci_endpoint_context_t*)device_context;
        device_context += xhci->context_size;
    }

    // Enable slot context and ep0 context
    XHCI_WRITE32(&icc->add_context_flags, XHCI_ICC_SLOT_FLAG | XHCI_ICC_EP_FLAG(0));

    // Setup slot context
    uint32_t route_string = xhci_get_route_string(xhci, hub_address, port);
    XHCI_SET_BITS32(&sc->sc0, SLOT_CTX_ROUTE_STRING_START, SLOT_CTX_ROUTE_STRING_BITS,
                    route_string);
    XHCI_SET_BITS32(&sc->sc0, SLOT_CTX_SPEED_START, SLOT_CTX_SPEED_BITS, speed);
    XHCI_SET_BITS32(&sc->sc0, SLOT_CTX_CONTEXT_ENTRIES_START, SLOT_CTX_CONTEXT_ENTRIES_BITS, 1);
    XHCI_SET_BITS32(&sc->sc1, SLOT_CTX_ROOT_HUB_PORT_NUM_START, SLOT_CTX_ROOT_HUB_PORT_NUM_BITS,
                    slot->rh_port);

    uint32_t mtt = 0;
    uint32_t tt_hub_slot_id = 0;
    uint32_t tt_port_number = 0;
    if (hub_address != 0 && (speed == USB_SPEED_LOW || speed == USB_SPEED_FULL)) {
        xhci_slot_t* hub_slot = &xhci->slots[hub_address];
        tt_hub_slot_id =  XHCI_GET_BITS32(&hub_slot->sc->sc2, SLOT_CTX_TT_HUB_SLOT_ID_START,
                                          SLOT_CTX_TT_HUB_SLOT_ID_BITS);
        if (tt_hub_slot_id) {
            tt_port_number = XHCI_GET_BITS32(&hub_slot->sc->sc2,  SLOT_CTX_TT_PORT_NUM_START,
                                             SLOT_CTX_TT_PORT_NUM_BITS);
            mtt = XHCI_GET_BITS32(&hub_slot->sc->sc0, SLOT_CTX_MTT_START, SLOT_CTX_MTT_BITS);
        } else if (hub_slot->speed == USB_SPEED_HIGH) {
            mtt = XHCI_GET_BITS32(&hub_slot->sc->sc0, SLOT_CTX_MTT_START, SLOT_CTX_MTT_BITS);
            tt_hub_slot_id = hub_address;
            tt_port_number = port;
        }
    }

    XHCI_SET_BITS32(&sc->sc0, SLOT_CTX_MTT_START, SLOT_CTX_MTT_BITS, mtt);
    XHCI_SET_BITS32(&sc->sc2, SLOT_CTX_TT_HUB_SLOT_ID_START, SLOT_CTX_TT_HUB_SLOT_ID_BITS,
                    tt_hub_slot_id);
    XHCI_SET_BITS32(&sc->sc2, SLOT_CTX_TT_PORT_NUM_START, SLOT_CTX_TT_PORT_NUM_BITS,
                    tt_port_number);

    // Setup endpoint context for ep0
    zx_paddr_t tr_dequeue = xhci_transfer_ring_start_phys(transfer_ring);

    // start off with reasonable default max packet size for ep0 based on speed
    int mps;
    switch (speed) {
        case USB_SPEED_SUPER:
            mps = 512;
            break;
        case USB_SPEED_FULL:
        case USB_SPEED_HIGH:
            mps = 64;
            break;
        case USB_SPEED_LOW:
        default:
            mps = 8;
            break;
    }

    XHCI_SET_BITS32(&ep0c->epc1, EP_CTX_CERR_START, EP_CTX_CERR_BITS, 3); // ???
    XHCI_SET_BITS32(&ep0c->epc1, EP_CTX_EP_TYPE_START, EP_CTX_EP_TYPE_BITS, EP_CTX_EP_TYPE_CONTROL);
    XHCI_SET_BITS32(&ep0c->epc1, EP_CTX_MAX_PACKET_SIZE_START, EP_CTX_MAX_PACKET_SIZE_BITS, mps);
    XHCI_WRITE32(&ep0c->epc2, ((uint32_t)tr_dequeue & EP_CTX_TR_DEQUEUE_LO_MASK) | EP_CTX_DCS);
    XHCI_WRITE32(&ep0c->tr_dequeue_hi, (uint32_t)(tr_dequeue >> 32));
    XHCI_SET_BITS32(&ep0c->epc4, EP_CTX_AVG_TRB_LENGTH_START, EP_CTX_AVG_TRB_LENGTH_BITS, 8); // ???

    // install our device context for the slot
    xhci_set_dbcaa(xhci, slot_id, io_buffer_phys(&slot->buffer));

    // then send the address device command
    for (int i = 0; i < 5; i++) {
        status = xhci_send_command(xhci, TRB_CMD_ADDRESS_DEVICE, icc_phys,
                                 (slot_id << TRB_SLOT_ID_START));
        if (status == ZX_OK) {
            break;
        } else if (status != ZX_ERR_TIMED_OUT) {
            usb_bus_reset_hub_port(&xhci->bus, hub_address, port);
            status = xhci_send_command(xhci, TRB_CMD_ADDRESS_DEVICE, icc_phys,
                                      ((slot_id << TRB_SLOT_ID_START) | TRB_ADDRESS_DEVICE_BSR));
            if (status != ZX_OK) {
                break;
            }
            usb_device_descriptor_t device_desc;
            // Based on XHCI spec 4.6.5, some legacy devices expect
            // device descriptor request prior to SET_ADDRESS request.
            status = xhci_get_descriptor(xhci, slot_id, USB_TYPE_STANDARD, USB_DT_DEVICE << 8, 0,
                                         &device_desc, 8);
            if (status != ZX_OK) {
                // try again
                continue;
            }
            switch (device_desc.bMaxPacketSize0) {
                case 8:
                case 16:
                case 32:
                case 64:
                case 255:
                    if (device_desc.bDescriptorType != USB_DT_DEVICE) {
                        status = ZX_ERR_IO;
                    }
                    break;
                default:
                    status = ZX_ERR_IO;
                    break;
            }
            if (status != ZX_OK) {
                // try again
                continue;
            }
            XHCI_SET_BITS32(&ep0c->epc1, EP_CTX_MAX_PACKET_SIZE_START, EP_CTX_MAX_PACKET_SIZE_BITS,
                            device_desc.bMaxPacketSize0);
            zx_nanosleep(zx_deadline_after(ZX_USEC(1000)));
            status = xhci_send_command(xhci, TRB_CMD_ADDRESS_DEVICE, icc_phys,
                                       (slot_id << TRB_SLOT_ID_START));
            if (status != ZX_OK){
                break;
            }
        }
    }
    mtx_unlock(&xhci->input_context_lock);

    if (status == ZX_OK) {
        ep->state = EP_STATE_RUNNING;
    }
    return status;
}

#define BOUNDS_CHECK(i, min, max) (i < min ? min : (i > max ? max : i))
#define LOG2(i) (31 - __builtin_clz(i))

static int compute_interval(usb_endpoint_descriptor_t* ep, usb_speed_t speed) {
    int ep_type = ep->bmAttributes & USB_ENDPOINT_TYPE_MASK;
    int interval = ep->bInterval;

    if (ep_type == USB_ENDPOINT_CONTROL || ep_type == USB_ENDPOINT_BULK) {
        if (speed == USB_SPEED_HIGH) {
            return LOG2(interval);
        } else {
            return 0;
        }
    }

    // now we deal with interrupt and isochronous endpoints
    // first make sure bInterval is in legal range
    if (ep_type == USB_ENDPOINT_INTERRUPT && (speed == USB_SPEED_LOW || speed == USB_SPEED_FULL)) {
        interval = BOUNDS_CHECK(interval, 1, 255);
    } else {
        interval = BOUNDS_CHECK(interval, 1, 16);
    }

    switch (speed) {
    case USB_SPEED_LOW:
        return LOG2(interval) + 3; // + 3 to convert 125us to 1ms
    case USB_SPEED_FULL:
        if (ep_type == USB_ENDPOINT_ISOCHRONOUS) {
            return (interval - 1) + 3;
        } else {
            return LOG2(interval) + 3;
        }
    case USB_SPEED_SUPER:
    case USB_SPEED_HIGH:
        return interval - 1;
    default:
        return 0;
    }
}

static void xhci_disable_slot(xhci_t* xhci, uint32_t slot_id) {
    xhci_send_command(xhci, TRB_CMD_DISABLE_SLOT, 0, (slot_id << TRB_SLOT_ID_START));

    zxlogf(TRACE, "cleaning up slot %d\n", slot_id);
    xhci_slot_t* slot = &xhci->slots[slot_id];
    for (int i = 0; i < XHCI_NUM_EPS; i++) {
        xhci_endpoint_t* ep = &slot->eps[i];
        xhci_transfer_ring_free(&ep->transfer_ring);
        free(ep->transfer_state);
        ep->transfer_state = NULL;
        ep->state = EP_STATE_DISABLED;
    }
    io_buffer_release(&slot->buffer);
    slot->sc = NULL;
    slot->hub_address = 0;
    slot->port = 0;
    slot->rh_port = 0;
    slot->port = USB_SPEED_UNDEFINED;
}

static zx_status_t xhci_handle_enumerate_device(xhci_t* xhci, uint32_t hub_address, uint32_t port,
                                                usb_speed_t speed) {
    zxlogf(TRACE, "xhci_handle_enumerate_device hub_address:%d port %d\n", hub_address, port);
    zx_status_t result = ZX_OK;
    uint32_t slot_id = 0;

    xhci_sync_command_t command;
    xhci_sync_command_init(&command);
    xhci_post_command(xhci, TRB_CMD_ENABLE_SLOT, 0, 0, &command.context);
    int cc = xhci_sync_command_wait(&command);
    if (cc == TRB_CC_SUCCESS) {
        slot_id = xhci_sync_command_slot_id(&command);
    } else {
        zxlogf(ERROR, "xhci_handle_enumerate_device: unable to get a slot\n");
        return ZX_ERR_NO_RESOURCES;
    }

    result = xhci_address_device(xhci, slot_id, hub_address, port, speed);
    if (result != ZX_OK) {
        goto disable_slot_exit;
    }
    // Let SET_ADDRESS settle down
    zx_nanosleep(zx_deadline_after(ZX_MSEC(10)));
    // read first 8 bytes of device descriptor to fetch ep0 max packet size
    usb_device_descriptor_t device_descriptor;
    for (int i = 0; i < 5; i++) {
        result = xhci_get_descriptor(xhci, slot_id, USB_TYPE_STANDARD, USB_DT_DEVICE << 8, 0,
                                     &device_descriptor, 8);
        if (result == ZX_ERR_IO_REFUSED || result == ZX_ERR_IO_INVALID) {
            xhci_reset_endpoint(xhci, slot_id, 0);
        } else {
            break;
        }
    }
    if (result != 8) {
        zxlogf(ERROR, "xhci_handle_enumerate_device: xhci_get_descriptor failed: %d\n", result);
        goto disable_slot_exit;
    }

    int mps = device_descriptor.bMaxPacketSize0;
    // enforce correct max packet size for ep0
    switch (speed) {
        case USB_SPEED_LOW:
            mps = 8;
            break;
        case USB_SPEED_FULL:
            if (mps != 8 && mps != 16 && mps != 32 && mps != 64) {
                mps = 8;
            }
            break;
        case USB_SPEED_HIGH:
            mps = 64;
            break;
        case USB_SPEED_SUPER:
            // bMaxPacketSize0 is an exponent for superspeed devices
            mps = 1 << mps;
            break;
        default:
            break;
    }

    // update the max packet size in our device context
    mtx_lock(&xhci->input_context_lock);
    xhci_input_control_context_t* icc = (xhci_input_control_context_t*)xhci->input_context;
    zx_paddr_t icc_phys = xhci->input_context_phys;
    xhci_endpoint_context_t* ep0c = (xhci_endpoint_context_t*)
                                            &xhci->input_context[2 * xhci->context_size];
    memset((void*)icc, 0, xhci->context_size);
    memset((void*)ep0c, 0, xhci->context_size);

    XHCI_WRITE32(&icc->add_context_flags, XHCI_ICC_EP_FLAG(0));
    XHCI_SET_BITS32(&ep0c->epc1, EP_CTX_MAX_PACKET_SIZE_START, EP_CTX_MAX_PACKET_SIZE_BITS, mps);

    result = xhci_send_command(xhci, TRB_CMD_EVAL_CONTEXT, icc_phys,
                               (slot_id << TRB_SLOT_ID_START));
    mtx_unlock(&xhci->input_context_lock);
    if (result != ZX_OK) {
        zxlogf(ERROR, "xhci_handle_enumerate_device: TRB_CMD_EVAL_CONTEXT failed\n");
        goto disable_slot_exit;
    }

    xhci_add_device(xhci, slot_id, hub_address, speed);
    return ZX_OK;

disable_slot_exit:
    xhci_disable_slot(xhci, slot_id);
    zxlogf(ERROR, "xhci_handle_enumerate_device failed %d\n", result);
    return result;
}

static zx_status_t xhci_stop_endpoint(xhci_t* xhci, uint32_t slot_id, int ep_index,
                                      xhci_ep_state_t new_state, zx_status_t complete_status) {
    xhci_slot_t* slot = &xhci->slots[slot_id];
    xhci_endpoint_t* ep =  &slot->eps[ep_index];
    xhci_transfer_ring_t* transfer_ring = &ep->transfer_ring;

    if (new_state == EP_STATE_RUNNING) {
        return ZX_ERR_INTERNAL;
    }

    mtx_lock(&ep->lock);
    if (ep->state != EP_STATE_RUNNING) {
        mtx_unlock(&ep->lock);
        return ZX_ERR_BAD_STATE;
    }
    ep->state = new_state;
    mtx_unlock(&ep->lock);

    xhci_sync_command_t command;
    xhci_sync_command_init(&command);
    // command expects device context index, so increment ep_index by 1
    uint32_t control = (slot_id << TRB_SLOT_ID_START) | ((ep_index + 1) << TRB_ENDPOINT_ID_START);
    xhci_post_command(xhci, TRB_CMD_STOP_ENDPOINT, 0, control, &command.context);
    int cc = xhci_sync_command_wait(&command);
    if (cc != TRB_CC_SUCCESS && cc != TRB_CC_CONTEXT_STATE_ERROR) {
        // TRB_CC_CONTEXT_STATE_ERROR is normal here in the case of a disconnected device,
        // since by then the endpoint would already be in error state.
        zxlogf(ERROR, "xhci_stop_endpoint: TRB_CMD_STOP_ENDPOINT failed cc: %d\n", cc);
        return ZX_ERR_INTERNAL;
    }

    free(ep->transfer_state);
    ep->transfer_state = NULL;
    xhci_transfer_ring_free(transfer_ring);

    // complete any remaining requests
    usb_request_t* req;
    while ((req = list_remove_head_type(&ep->pending_reqs, usb_request_t, node))) {
        usb_request_complete(req, complete_status, 0);
    }
    while ((req = list_remove_head_type(&ep->queued_reqs, usb_request_t, node))) {
        usb_request_complete(req, complete_status, 0);
    }

    return ZX_OK;
}

static zx_status_t xhci_handle_disconnect_device(xhci_t* xhci, uint32_t hub_address, uint32_t port) {
    zxlogf(TRACE, "xhci_handle_disconnect_device\n");
    xhci_slot_t* slot = NULL;
    uint32_t slot_id;

    int rh_index = xhci_get_root_hub_index(xhci, hub_address);
    if (rh_index >= 0) {
        // For virtual root hub devices, real hub_address is 0
        hub_address = 0;
        // convert virtual root hub port number to real port number
        port = xhci->root_hubs[rh_index].port_map[port - 1] + 1;
    }

    for (slot_id = 1; slot_id <= xhci->max_slots; slot_id++) {
        xhci_slot_t* test_slot = &xhci->slots[slot_id];
        if (test_slot->hub_address == hub_address && test_slot->port == port) {
            slot = test_slot;
            break;
        }
    }
    if (!slot) {
        zxlogf(ERROR, "slot not found in xhci_handle_disconnect_device\n");
        return ZX_ERR_NOT_FOUND;
    }

    uint32_t drop_flags = 0;
    for (int i = 0; i < XHCI_NUM_EPS; i++) {
        if (slot->eps[i].state != EP_STATE_DEAD) {
            zx_status_t status = xhci_stop_endpoint(xhci, slot_id, i, EP_STATE_DEAD,
                                                    ZX_ERR_IO_NOT_PRESENT);
            if (status != ZX_OK) {
                zxlogf(ERROR, "xhci_handle_disconnect_device: xhci_stop_endpoint failed: %d\n",
                        status);
            }
            drop_flags |= XHCI_ICC_EP_FLAG(i);
         }
    }

    xhci_remove_device(xhci, slot_id);

    mtx_lock(&xhci->input_context_lock);
    xhci_input_control_context_t* icc = (xhci_input_control_context_t*)xhci->input_context;
    zx_paddr_t icc_phys = xhci->input_context_phys;
    memset((void*)icc, 0, xhci->context_size);
    XHCI_WRITE32(&icc->drop_context_flags, drop_flags);

    zx_status_t status = xhci_send_command(xhci, TRB_CMD_CONFIGURE_EP, icc_phys,
                                           (slot_id << TRB_SLOT_ID_START));
    mtx_unlock(&xhci->input_context_lock);
    if (status != ZX_OK) {
        zxlogf(ERROR, "xhci_handle_disconnect_device: TRB_CMD_CONFIGURE_EP failed\n");
    }

    xhci_disable_slot(xhci, slot_id);

    return ZX_OK;
}

static int xhci_device_thread(void* arg) {
    xhci_t* xhci = (xhci_t*)arg;

    while (1) {
        zxlogf(TRACE, "xhci_device_thread top of loop\n");
        // wait for a device to enumerate
        completion_wait(&xhci->command_queue_completion, ZX_TIME_INFINITE);

        mtx_lock(&xhci->command_queue_mutex);
        list_node_t* node = list_remove_head(&xhci->command_queue);
        xhci_device_command_t* command =
                                    (node ? containerof(node, xhci_device_command_t, node) : NULL);
        if (list_is_empty(&xhci->command_queue)) {
            completion_reset(&xhci->command_queue_completion);
        }
        mtx_unlock(&xhci->command_queue_mutex);

        if (!command) {
            zxlogf(ERROR, "xhci_device_thread: command_queue_completion was signaled, "
                    "but no command was found");
            break;
        }

        switch (command->command) {
        case ENUMERATE_DEVICE:
            xhci_handle_enumerate_device(xhci, command->hub_address, command->port, command->speed);
            break;
        case DISCONNECT_DEVICE:
            xhci_handle_disconnect_device(xhci, command->hub_address, command->port);
            break;
        case START_ROOT_HUBS:
            xhci_start_root_hubs(xhci);
            break;
        case STOP_THREAD:
            return 0;
        }
    }

    return 0;
}

static zx_status_t xhci_queue_command(xhci_t* xhci, int command, uint32_t hub_address,
                                      uint32_t port, usb_speed_t speed) {
    xhci_device_command_t* device_command = calloc(1, sizeof(xhci_device_command_t));
    if (!device_command) {
        return ZX_ERR_NO_MEMORY;
    }
    device_command->command = command;
    device_command->hub_address = hub_address;
    device_command->port = port;
    device_command->speed = speed;

    mtx_lock(&xhci->command_queue_mutex);
    list_add_tail(&xhci->command_queue, &device_command->node);
    completion_signal(&xhci->command_queue_completion);
    mtx_unlock(&xhci->command_queue_mutex);

    return ZX_OK;
}

void xhci_start_device_thread(xhci_t* xhci) {
    thrd_create_with_name(&xhci->device_thread, xhci_device_thread, xhci, "xhci_device_thread");
}

void xhci_stop_device_thread(xhci_t* xhci) {
    xhci_queue_command(xhci, STOP_THREAD, 0, 0, 0);
    thrd_join(xhci->device_thread, NULL);
}

zx_status_t xhci_enumerate_device(xhci_t* xhci, uint32_t hub_address, uint32_t port,
                                  usb_speed_t speed) {
    return xhci_queue_command(xhci, ENUMERATE_DEVICE, hub_address, port, speed);
}

zx_status_t xhci_device_disconnected(xhci_t* xhci, uint32_t hub_address, uint32_t port) {
    zxlogf(TRACE, "xhci_device_disconnected %d %d\n", hub_address, port);
    mtx_lock(&xhci->command_queue_mutex);
    // check pending device list first
    xhci_device_command_t* command;
    list_for_every_entry (&xhci->command_queue, command, xhci_device_command_t, node) {
        if (command->command == ENUMERATE_DEVICE && command->hub_address == hub_address &&
            command->port == port) {
            zxlogf(TRACE, "found on pending list\n");
            list_delete(&command->node);
            mtx_unlock(&xhci->command_queue_mutex);
            return ZX_OK;
        }
    }
    mtx_unlock(&xhci->command_queue_mutex);

    return xhci_queue_command(xhci, DISCONNECT_DEVICE, hub_address, port, USB_SPEED_UNDEFINED);
}

zx_status_t xhci_queue_start_root_hubs(xhci_t* xhci) {
    return xhci_queue_command(xhci, START_ROOT_HUBS, 0, 0, USB_SPEED_UNDEFINED);
}

static zx_status_t xhci_update_input_context(xhci_t* xhci, uint32_t slot_id, int ep_index) {
    zx_paddr_t icc_phys = xhci->input_context_phys;

    return xhci_send_command(xhci, TRB_CMD_CONFIGURE_EP, icc_phys, (slot_id << TRB_SLOT_ID_START));
}

zx_status_t xhci_enable_endpoint(xhci_t* xhci, uint32_t slot_id, usb_endpoint_descriptor_t* ep_desc,
                                 usb_ss_ep_comp_descriptor_t* ss_comp_desc, bool enable) {
    if (xhci_is_root_hub(xhci, slot_id)) {
        // nothing to do for root hubs
        return ZX_OK;
    }

    xhci_slot_t* slot = &xhci->slots[slot_id];
    usb_speed_t speed = slot->speed;
    uint32_t index = xhci_endpoint_index(ep_desc->bEndpointAddress);
    xhci_endpoint_t* ep = &slot->eps[index];
    ep->ep_type = usb_ep_type(ep_desc);
    ep->max_packet_size = usb_ep_max_packet(ep_desc);

    mtx_lock(&ep->lock);

    if ((enable && ep->state == EP_STATE_RUNNING) || (!enable && ep->state == EP_STATE_DISABLED)) {
        mtx_unlock(&ep->lock);
        return ZX_OK;
    }

    mtx_lock(&xhci->input_context_lock);
    xhci_input_control_context_t* icc = (xhci_input_control_context_t*)xhci->input_context;
    xhci_slot_context_t* sc = (xhci_slot_context_t*)&xhci->input_context[1 * xhci->context_size];
    memset((void*)icc, 0, xhci->context_size);

    if (enable) {
        memset((void*)sc, 0, xhci->context_size);

        uint32_t ep_type = ep_desc->bmAttributes & USB_ENDPOINT_TYPE_MASK;
        uint32_t ep_index = ep_type;
        if ((ep_desc->bEndpointAddress & USB_ENDPOINT_DIR_MASK) == USB_ENDPOINT_IN) {
            ep_index += 4;
        }

        // See Table 65 in XHCI spec
        int cerr = (ep_type == USB_ENDPOINT_ISOCHRONOUS ? 0 : 3);
        int max_packet_size = usb_ep_max_packet(ep_desc);

        int max_burst = 0;
        if (speed == USB_SPEED_SUPER) {
            if (ss_comp_desc != NULL) {
                max_burst = ss_comp_desc->bMaxBurst;
            }
        } else if (speed == USB_SPEED_HIGH) {
            if (ep_type == USB_ENDPOINT_ISOCHRONOUS) {
                max_burst = usb_ep_add_mf_transactions(ep_desc);
            }
        }

        int avg_trb_length = max_packet_size * max_burst;
        int max_esit_payload = 0;
        if (ep_type == USB_ENDPOINT_ISOCHRONOUS) {
            // FIXME - more work needed for superspeed here
            max_esit_payload = max_packet_size * max_burst;
        }

        xhci_endpoint_context_t* epc =
                (xhci_endpoint_context_t*)&xhci->input_context[(index + 2) * xhci->context_size];
        memset((void*)epc, 0, xhci->context_size);
        // allocate a transfer ring for the endpoint
        zx_status_t status = xhci_transfer_ring_init(&ep->transfer_ring, xhci->bti_handle, TRANSFER_RING_SIZE);
        if (status < 0) {
            mtx_unlock(&xhci->input_context_lock);
            mtx_unlock(&ep->lock);
            return status;
        }

        zx_paddr_t tr_dequeue = xhci_transfer_ring_start_phys(&slot->eps[index].transfer_ring);

        XHCI_SET_BITS32(&epc->epc0, EP_CTX_INTERVAL_START, EP_CTX_INTERVAL_BITS,
                        compute_interval(ep_desc, speed));
        XHCI_SET_BITS32(&epc->epc0, EP_CTX_MAX_ESIT_PAYLOAD_HI_START,
                        EP_CTX_MAX_ESIT_PAYLOAD_HI_BITS,
                        max_esit_payload >> EP_CTX_MAX_ESIT_PAYLOAD_LO_BITS);
        XHCI_SET_BITS32(&epc->epc1, EP_CTX_CERR_START, EP_CTX_CERR_BITS, cerr);
        XHCI_SET_BITS32(&epc->epc1, EP_CTX_EP_TYPE_START, EP_CTX_EP_TYPE_BITS, ep_index);
        XHCI_SET_BITS32(&epc->epc1, EP_CTX_MAX_PACKET_SIZE_START, EP_CTX_MAX_PACKET_SIZE_BITS,
                        max_packet_size);
        XHCI_SET_BITS32(&epc->epc1, EP_CTX_MAX_BURST_SIZE_START, EP_CTX_MAX_BURST_SIZE_BITS,
                        max_burst);

        XHCI_WRITE32(&epc->epc2, ((uint32_t)tr_dequeue & EP_CTX_TR_DEQUEUE_LO_MASK) | EP_CTX_DCS);
        XHCI_WRITE32(&epc->tr_dequeue_hi, (uint32_t)(tr_dequeue >> 32));
        XHCI_SET_BITS32(&epc->epc4, EP_CTX_AVG_TRB_LENGTH_START, EP_CTX_AVG_TRB_LENGTH_BITS,
                        avg_trb_length);
        XHCI_SET_BITS32(&epc->epc4, EP_CTX_MAX_ESIT_PAYLOAD_LO_START,
                        EP_CTX_MAX_ESIT_PAYLOAD_LO_BITS, max_esit_payload);

        XHCI_WRITE32(&icc->add_context_flags, XHCI_ICC_SLOT_FLAG | XHCI_ICC_EP_FLAG(index));

        XHCI_WRITE32(&sc->sc0, XHCI_READ32(&slot->sc->sc0));
        XHCI_WRITE32(&sc->sc1, XHCI_READ32(&slot->sc->sc1));
        XHCI_WRITE32(&sc->sc2, XHCI_READ32(&slot->sc->sc2));
        XHCI_SET_BITS32(&sc->sc0, SLOT_CTX_CONTEXT_ENTRIES_START, SLOT_CTX_CONTEXT_ENTRIES_BITS,
                        index + 1);

        status = xhci_update_input_context(xhci, slot_id, index);
        mtx_unlock(&xhci->input_context_lock);

        // xhci_stop_endpoint() will handle the !enable case
        if (status == ZX_OK) {
            ep->transfer_state = calloc(1, sizeof(xhci_transfer_state_t));
            if (!ep->transfer_state) {
                status = ZX_ERR_NO_MEMORY;
            } else {
                ep->state = EP_STATE_RUNNING;
            }
        }
        mtx_unlock(&ep->lock);
        return status;
    } else {
        // xhci_stop_endpoint will try to acquire the endpoint lock.
        // It also needs to wait for the TRB_CMD_STOP_ENDPOINT completion, which may never
        // complete if another xhci event is waiting for the same endpoint lock.
        mtx_unlock(&ep->lock);
        xhci_stop_endpoint(xhci, slot_id, index, EP_STATE_DISABLED, ZX_ERR_BAD_STATE);
        XHCI_WRITE32(&icc->drop_context_flags, XHCI_ICC_EP_FLAG(index));
        zx_status_t status = xhci_update_input_context(xhci, slot_id, index);
        mtx_unlock(&xhci->input_context_lock);
        return status;
    }
}

zx_status_t xhci_configure_hub(xhci_t* xhci, uint32_t slot_id, usb_speed_t speed,
                               usb_hub_descriptor_t* descriptor) {
    zxlogf(TRACE, "xhci_configure_hub slot_id: %d speed: %d\n", slot_id, speed);
    if (xhci_is_root_hub(xhci, slot_id)) {
        // nothing to do for root hubs
        return ZX_OK;
    }
    if (slot_id > xhci->max_slots) return ZX_ERR_INVALID_ARGS;

    xhci_slot_t* slot = &xhci->slots[slot_id];
    uint32_t num_ports = descriptor->bNbrPorts;
    uint32_t ttt = 0;
    if (speed == USB_SPEED_HIGH) {
        ttt = (descriptor->wHubCharacteristics >> 5) & 3;
    }
    //TODO: Check for MTT. Needs a hook for calling set_interface from usb layer.

    mtx_lock(&xhci->input_context_lock);
    xhci_input_control_context_t* icc = (xhci_input_control_context_t*)xhci->input_context;
    zx_paddr_t icc_phys = xhci->input_context_phys;
    xhci_slot_context_t* sc = (xhci_slot_context_t*)&xhci->input_context[1 * xhci->context_size];
    memset((void*)icc, 0, xhci->context_size);
    memset((void*)sc, 0, xhci->context_size);

    XHCI_WRITE32(&icc->add_context_flags, XHCI_ICC_SLOT_FLAG);
    XHCI_WRITE32(&sc->sc0, XHCI_READ32(&slot->sc->sc0) | SLOT_CTX_HUB);
    XHCI_WRITE32(&sc->sc1, XHCI_READ32(&slot->sc->sc1));
    XHCI_WRITE32(&sc->sc2, XHCI_READ32(&slot->sc->sc2));

    XHCI_SET_BITS32(&sc->sc1, SLOT_CTX_ROOT_NUM_PORTS_START, SLOT_CTX_ROOT_NUM_PORTS_BITS,
                    num_ports);
    XHCI_SET_BITS32(&sc->sc2, SLOT_CTX_TTT_START, SLOT_CTX_TTT_BITS, ttt);

    zx_status_t status = xhci_send_command(xhci, TRB_CMD_EVAL_CONTEXT, icc_phys,
                                           (slot_id << TRB_SLOT_ID_START));
    mtx_unlock(&xhci->input_context_lock);

    if (status != ZX_OK) {
        zxlogf(ERROR, "xhci_configure_hub: TRB_CMD_EVAL_CONTEXT failed\n");
        return status;
    }

    if (speed == USB_SPEED_SUPER) {
        // compute hub depth
        int depth = 0;
        while (slot->hub_address != 0) {
            depth++;
            slot = &xhci->slots[slot->hub_address];
        }

        zxlogf(TRACE, "USB_HUB_SET_DEPTH %d\n", depth);
        zx_status_t result = xhci_control_request(xhci, slot_id,
                                      USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_DEVICE,
                                      USB_HUB_SET_DEPTH, depth, 0, NULL, 0);
        if (result < 0) {
            zxlogf(ERROR, "xhci_configure_hub: USB_HUB_SET_DEPTH failed\n");
        }
    }

    return ZX_OK;
}