source: mainline/uspace/drv/bus/usb/xhci/hc.c@ 69b2dfee

/*
 * Copyright (c) 2017 Ondrej Hlavaty
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup drvusbxhci
 * @{
 */
/** @file
 * @brief The host controller data bookkeeping.
 */

#include <errno.h>
#include <str_error.h>
#include <usb/debug.h>
#include <usb/host/endpoint.h>
#include "debug.h"
#include "hc.h"
#include "rh.h"
#include "hw_struct/trb.h"
#include "hw_struct/context.h"
#include "endpoint.h"
#include "transfers.h"
#include "trb_ring.h"

/**
 * Default USB Speed ID mapping: Table 157
 */
#define PSI_TO_BPS(psie, psim) (((uint64_t) psim) << (10 * psie))
#define PORT_SPEED(usb, mjr, psie, psim) { \
        .name = "USB ", \
        .major = mjr, \
        .minor = 0, \
        .usb_speed = USB_SPEED_##usb, \
        .rx_bps = PSI_TO_BPS(psie, psim), \
        .tx_bps = PSI_TO_BPS(psie, psim) \
}

static const xhci_port_speed_t default_psiv_to_port_speed [] = {
        [1] = PORT_SPEED(FULL, 2, 2, 12),
        [2] = PORT_SPEED(LOW, 2, 1, 1500),
        [3] = PORT_SPEED(HIGH, 2, 2, 480),
        [4] = PORT_SPEED(SUPER, 3, 3, 5),
};

static const unsigned usb_speed_to_psiv [] = {
        [USB_SPEED_FULL] = 1,
        [USB_SPEED_LOW] = 2,
        [USB_SPEED_HIGH] = 3,
        [USB_SPEED_SUPER] = 4,
};

/**
 * Walk the list of extended capabilities.
 *
 * The most interesting thing hidden in extended capabilities is the mapping of
 * ports to protocol versions and speeds.
 */
static int hc_parse_ec(xhci_hc_t *hc)
{
        unsigned psic, major, minor;
        xhci_sp_name_t name;

        xhci_port_speed_t *speeds = hc->speeds;

        for (xhci_extcap_t *ec = hc->xecp; ec; ec = xhci_extcap_next(ec)) {
                xhci_dump_extcap(ec);
                switch (XHCI_REG_RD(ec, XHCI_EC_CAP_ID)) {
                case XHCI_EC_USB_LEGACY:
                        assert(hc->legsup == NULL);
                        hc->legsup = (xhci_legsup_t *) ec;
                        break;
                case XHCI_EC_SUPPORTED_PROTOCOL:
                        psic = XHCI_REG_RD(ec, XHCI_EC_SP_PSIC);
                        major = XHCI_REG_RD(ec, XHCI_EC_SP_MAJOR);
                        minor = XHCI_REG_RD(ec, XHCI_EC_SP_MINOR);
                        name.packed = host2uint32_t_le(XHCI_REG_RD(ec, XHCI_EC_SP_NAME));

                        if (name.packed != xhci_name_usb.packed) {
                                /**
                                 * The detection of such protocol would work,
                                 * but the rest of the implementation is made
                                 * for the USB protocol only.
                                 */
                                usb_log_error("Unknown protocol %.4s.", name.str);
                                return ENOTSUP;
                        }

                        unsigned offset = XHCI_REG_RD(ec, XHCI_EC_SP_CP_OFF);
                        unsigned count = XHCI_REG_RD(ec, XHCI_EC_SP_CP_COUNT);
                        xhci_rh_set_ports_protocol(&hc->rh, offset, count, major);

                        // "Implied" speed
                        if (psic == 0) {
                                assert(minor == 0);

                                if (major == 2) {
                                        speeds[1] = default_psiv_to_port_speed[1];
                                        speeds[2] = default_psiv_to_port_speed[2];
                                        speeds[3] = default_psiv_to_port_speed[3];
                                } else if (major == 3) {
                                        speeds[4] = default_psiv_to_port_speed[4];
                                } else {
                                        return EINVAL;
                                }

                                usb_log_debug2("Implied speed of USB %u.0 set up.", major);
                        } else {
                                for (unsigned i = 0; i < psic; i++) {
                                        xhci_psi_t *psi = xhci_extcap_psi(ec, i);
                                        unsigned sim = XHCI_REG_RD(psi, XHCI_PSI_PSIM);
                                        unsigned psiv = XHCI_REG_RD(psi, XHCI_PSI_PSIV);
                                        unsigned psie = XHCI_REG_RD(psi, XHCI_PSI_PSIE);
                                        unsigned psim = XHCI_REG_RD(psi, XHCI_PSI_PSIM);
                                        uint64_t bps = PSI_TO_BPS(psie, psim);

                                        /*
                                         * Speed is not implied, but using one of default PSIV. This is
                                         * not clearly stated in xHCI spec. There is a clear intention
                                         * to allow xHCI to specify its own speed parameters, but
                                         * throughout the document, they used fixed values for e.g.
                                         * High-speed (3), without stating the controller shall have
                                         * implied default speeds - and for instance Intel controllers
                                         * do not. So let's check if the values match and if so, accept
                                         * the implied USB speed too.
                                         *
                                         * The main reason we need this is the usb_speed to have
                                         * mapping also for devices connected to hubs.
                                         */
                                        if (psiv < ARRAY_SIZE(default_psiv_to_port_speed)
                                           && default_psiv_to_port_speed[psiv].major == major
                                           && default_psiv_to_port_speed[psiv].minor == minor
                                           && default_psiv_to_port_speed[psiv].rx_bps == bps
                                           && default_psiv_to_port_speed[psiv].tx_bps == bps) {
                                                speeds[psiv] = default_psiv_to_port_speed[psiv];
                                                usb_log_debug2("Assumed default %s speed of USB %u.", usb_str_speed(speeds[psiv].usb_speed), major);
                                                continue;
                                        }

                                        // Custom speed
                                        speeds[psiv].major = major;
                                        speeds[psiv].minor = minor;
                                        str_ncpy(speeds[psiv].name, 4, name.str, 4);
                                        speeds[psiv].usb_speed = USB_SPEED_MAX;

                                        if (sim == XHCI_PSI_PLT_SYMM || sim == XHCI_PSI_PLT_RX)
                                                speeds[psiv].rx_bps = bps;
                                        if (sim == XHCI_PSI_PLT_SYMM || sim == XHCI_PSI_PLT_TX) {
                                                speeds[psiv].tx_bps = bps;
                                                usb_log_debug2("Speed %u set up for bps %" PRIu64 " / %" PRIu64 ".", psiv, speeds[psiv].rx_bps, speeds[psiv].tx_bps);
                                        }
                                }
                        }
                }
        }
        return EOK;
}

/**
 * Initialize MMIO spaces of xHC.
 */
int hc_init_mmio(xhci_hc_t *hc, const hw_res_list_parsed_t *hw_res)
{
        int err;

        if (hw_res->mem_ranges.count != 1) {
                usb_log_error("Unexpected MMIO area, bailing out.");
                return EINVAL;
        }

        hc->mmio_range = hw_res->mem_ranges.ranges[0];

        usb_log_debug("MMIO area at %p (size %zu), IRQ %d.",
            RNGABSPTR(hc->mmio_range), RNGSZ(hc->mmio_range), hw_res->irqs.irqs[0]);

        if (RNGSZ(hc->mmio_range) < sizeof(xhci_cap_regs_t))
                return EOVERFLOW;

        void *base;
        if ((err = pio_enable_range(&hc->mmio_range, &base)))
                return err;

        hc->reg_base = base;
        hc->cap_regs = (xhci_cap_regs_t *)  base;
        hc->op_regs  = (xhci_op_regs_t *)  (base + XHCI_REG_RD(hc->cap_regs, XHCI_CAP_LENGTH));
        hc->rt_regs  = (xhci_rt_regs_t *)  (base + XHCI_REG_RD(hc->cap_regs, XHCI_CAP_RTSOFF));
        hc->db_arry  = (xhci_doorbell_t *) (base + XHCI_REG_RD(hc->cap_regs, XHCI_CAP_DBOFF));

        uintptr_t xec_offset = XHCI_REG_RD(hc->cap_regs, XHCI_CAP_XECP) * sizeof(xhci_dword_t);
        if (xec_offset > 0)
                hc->xecp = (xhci_extcap_t *) (base + xec_offset);

        usb_log_debug2("Initialized MMIO reg areas:");
        usb_log_debug2("\tCapability regs: %p", hc->cap_regs);
        usb_log_debug2("\tOperational regs: %p", hc->op_regs);
        usb_log_debug2("\tRuntime regs: %p", hc->rt_regs);
        usb_log_debug2("\tDoorbell array base: %p", hc->db_arry);

        xhci_dump_cap_regs(hc->cap_regs);

        hc->ac64 = XHCI_REG_RD(hc->cap_regs, XHCI_CAP_AC64);
        hc->max_slots = XHCI_REG_RD(hc->cap_regs, XHCI_CAP_MAX_SLOTS);

        struct timeval tv;
        getuptime(&tv);
        hc->wrap_time = tv.tv_sec * 1000000 + tv.tv_usec;
        hc->wrap_count = 0;

        unsigned ist = XHCI_REG_RD(hc->cap_regs, XHCI_CAP_IST);
        hc->ist = (ist & 0x10 >> 1) * (ist & 0xf);

        if ((err = xhci_rh_init(&hc->rh, hc)))
                goto err_pio;

        if ((err = hc_parse_ec(hc)))
                goto err_rh;

        return EOK;

err_rh:
        xhci_rh_fini(&hc->rh);
err_pio:
        pio_disable(hc->reg_base, RNGSZ(hc->mmio_range));
        return err;
}

static int event_worker(void *arg);

/**
 * Initialize structures kept in allocated memory.
 */
int hc_init_memory(xhci_hc_t *hc, ddf_dev_t *device)
{
        int err;

        if (dma_buffer_alloc(&hc->dcbaa_dma, (1 + hc->max_slots) * sizeof(uint64_t)))
                return ENOMEM;
        hc->dcbaa = hc->dcbaa_dma.virt;

        if ((err = xhci_event_ring_init(&hc->event_ring)))
                goto err_dcbaa;

        if ((err = xhci_scratchpad_alloc(hc)))
                goto err_event_ring;

        if ((err = xhci_init_commands(hc)))
                goto err_scratch;

        if ((err = xhci_bus_init(&hc->bus, hc)))
                goto err_cmd;

        fid_t fid = fibril_create(&event_worker, hc);
        if (!fid)
                goto err_bus;

        // TODO: completion_reset
        hc->event_fibril_completion.active = true;
        fibril_mutex_initialize(&hc->event_fibril_completion.guard);
        fibril_condvar_initialize(&hc->event_fibril_completion.cv);

        xhci_sw_ring_init(&hc->sw_ring, PAGE_SIZE / sizeof(xhci_trb_t));

        fibril_add_ready(fid);

        return EOK;

err_bus:
        xhci_bus_fini(&hc->bus);
err_cmd:
        xhci_fini_commands(hc);
err_scratch:
        xhci_scratchpad_free(hc);
err_event_ring:
        xhci_event_ring_fini(&hc->event_ring);
err_dcbaa:
        hc->dcbaa = NULL;
        dma_buffer_free(&hc->dcbaa_dma);
        return err;
}

/*
 * Pseudocode:
 *      ip = read(intr[0].iman)
 *      if (ip) {
 *              status = read(usbsts)
 *              assert status
 *              assert ip
 *              accept (passing status)
 *      }
 *      decline
 */
static const irq_cmd_t irq_commands[] = {
        {
                .cmd = CMD_PIO_READ_32,
                .dstarg = 3,
                .addr = NULL    /* intr[0].iman */
        },
        {
                .cmd = CMD_AND,
                .srcarg = 3,
                .dstarg = 4,
                .value = 0      /* host2xhci(32, 1) */
        },
        {
                .cmd = CMD_PREDICATE,
                .srcarg = 4,
                .value = 5
        },
        {
                .cmd = CMD_PIO_READ_32,
                .dstarg = 1,
                .addr = NULL    /* usbsts */
        },
        {
                .cmd = CMD_AND,
                .srcarg = 1,
                .dstarg = 2,
                .value = 0      /* host2xhci(32, XHCI_STATUS_ACK_MASK) */
        },
        {
                .cmd = CMD_PIO_WRITE_A_32,
                .srcarg = 2,
                .addr = NULL    /* usbsts */
        },
        {
                .cmd = CMD_PIO_WRITE_A_32,
                .srcarg = 3,
                .addr = NULL    /* intr[0].iman */
        },
        {
                .cmd = CMD_ACCEPT
        },
        {
                .cmd = CMD_DECLINE
        }
};


/**
 * Generates code to accept interrupts. The xHCI is designed primarily for
 * MSI/MSI-X, but we use PCI Interrupt Pin. In this mode, all the Interrupters
 * (except 0) are disabled.
 */
int hc_irq_code_gen(irq_code_t *code, xhci_hc_t *hc, const hw_res_list_parsed_t *hw_res)
{
        assert(code);
        assert(hw_res);

        if (hw_res->irqs.count != 1) {
                usb_log_info("Unexpected HW resources to enable interrupts.");
                return EINVAL;
        }

        code->ranges = malloc(sizeof(irq_pio_range_t));
        if (code->ranges == NULL)
                return ENOMEM;

        code->cmds = malloc(sizeof(irq_commands));
        if (code->cmds == NULL) {
                free(code->ranges);
                return ENOMEM;
        }

        code->rangecount = 1;
        code->ranges[0] = (irq_pio_range_t) {
            .base = RNGABS(hc->mmio_range),
            .size = RNGSZ(hc->mmio_range),
        };

        code->cmdcount = ARRAY_SIZE(irq_commands);
        memcpy(code->cmds, irq_commands, sizeof(irq_commands));

        void *intr0_iman = RNGABSPTR(hc->mmio_range) + XHCI_REG_RD(hc->cap_regs, XHCI_CAP_RTSOFF) + offsetof(xhci_rt_regs_t, ir[0]);
        void *usbsts = RNGABSPTR(hc->mmio_range) + XHCI_REG_RD(hc->cap_regs, XHCI_CAP_LENGTH) + offsetof(xhci_op_regs_t, usbsts);
        code->cmds[0].addr = intr0_iman;
        code->cmds[1].value = host2xhci(32, 1);
        code->cmds[3].addr = usbsts;
        code->cmds[4].value = host2xhci(32, XHCI_STATUS_ACK_MASK);
        code->cmds[5].addr = usbsts;
        code->cmds[6].addr = intr0_iman;

        return hw_res->irqs.irqs[0];
}

/**
 * Claim xHC from BIOS. Implements handoff as per Section 4.22.1 of xHCI spec.
 */
int hc_claim(xhci_hc_t *hc, ddf_dev_t *dev)
{
        /* No legacy support capability, the controller is solely for us */
        if (!hc->legsup)
                return EOK;

        if (xhci_reg_wait(&hc->op_regs->usbsts, XHCI_REG_MASK(XHCI_OP_CNR), 0))
                return ETIMEOUT;

        usb_log_debug2("LEGSUP: bios: %x, os: %x", hc->legsup->sem_bios, hc->legsup->sem_os);
        XHCI_REG_SET(hc->legsup, XHCI_LEGSUP_SEM_OS, 1);
        for (int i = 0; i <= (XHCI_LEGSUP_BIOS_TIMEOUT_US / XHCI_LEGSUP_POLLING_DELAY_1MS); i++) {
                usb_log_debug2("LEGSUP: elapsed: %i ms, bios: %x, os: %x", i,
                        XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_BIOS),
                        XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_OS));
                if (XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_BIOS) == 0) {
                        return XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_OS) == 1 ? EOK : EIO;
                }
                async_usleep(XHCI_LEGSUP_POLLING_DELAY_1MS);
        }
        usb_log_error("BIOS did not release XHCI legacy hold!");

        return ENOTSUP;
}

/**
 * Ask the xHC to reset its state. Implements sequence
 */
static int hc_reset(xhci_hc_t *hc)
{
        if (xhci_reg_wait(&hc->op_regs->usbsts, XHCI_REG_MASK(XHCI_OP_CNR), 0))
                return ETIMEOUT;

        /* Stop the HC: set R/S to 0 */
        XHCI_REG_CLR(hc->op_regs, XHCI_OP_RS, 1);

        /* Wait until the HC is halted - it shall take at most 16 ms */
        if (xhci_reg_wait(&hc->op_regs->usbsts, XHCI_REG_MASK(XHCI_OP_HCH), XHCI_REG_MASK(XHCI_OP_HCH)))
                return ETIMEOUT;

        /* Reset */
        XHCI_REG_SET(hc->op_regs, XHCI_OP_HCRST, 1);

        /* Wait until the reset is complete */
        if (xhci_reg_wait(&hc->op_regs->usbcmd, XHCI_REG_MASK(XHCI_OP_HCRST), 0))
                return ETIMEOUT;

        return EOK;
}

/**
 * Initialize the HC: section 4.2
 */
int hc_start(xhci_hc_t *hc, bool irq)
{
        int err;

        if ((err = hc_reset(hc)))
                return err;

        if (xhci_reg_wait(&hc->op_regs->usbsts, XHCI_REG_MASK(XHCI_OP_CNR), 0))
                return ETIMEOUT;

        uint64_t dcbaaptr = hc->dcbaa_dma.phys;
        XHCI_REG_WR(hc->op_regs, XHCI_OP_DCBAAP_LO, LOWER32(dcbaaptr));
        XHCI_REG_WR(hc->op_regs, XHCI_OP_DCBAAP_HI, UPPER32(dcbaaptr));
        XHCI_REG_WR(hc->op_regs, XHCI_OP_MAX_SLOTS_EN, hc->max_slots);

        uintptr_t crcr;
        xhci_trb_ring_reset_dequeue_state(&hc->cr.trb_ring, &crcr);
        XHCI_REG_WR(hc->op_regs, XHCI_OP_CRCR_LO, LOWER32(crcr));
        XHCI_REG_WR(hc->op_regs, XHCI_OP_CRCR_HI, UPPER32(crcr));

        XHCI_REG_SET(hc->op_regs, XHCI_OP_EWE, 1);

        xhci_interrupter_regs_t *intr0 = &hc->rt_regs->ir[0];
        XHCI_REG_WR(intr0, XHCI_INTR_ERSTSZ, hc->event_ring.segment_count);
        uint64_t erdp = hc->event_ring.dequeue_ptr;
        XHCI_REG_WR(intr0, XHCI_INTR_ERDP_LO, LOWER32(erdp));
        XHCI_REG_WR(intr0, XHCI_INTR_ERDP_HI, UPPER32(erdp));
        uint64_t erstptr = hc->event_ring.erst.phys;
        XHCI_REG_WR(intr0, XHCI_INTR_ERSTBA_LO, LOWER32(erstptr));
        XHCI_REG_WR(intr0, XHCI_INTR_ERSTBA_HI, UPPER32(erstptr));


        if (irq) {
                XHCI_REG_SET(intr0, XHCI_INTR_IE, 1);
                XHCI_REG_SET(hc->op_regs, XHCI_OP_INTE, 1);
        }

        XHCI_REG_SET(hc->op_regs, XHCI_OP_HSEE, 1);

        XHCI_REG_SET(hc->op_regs, XHCI_OP_RS, 1);

        xhci_rh_startup(&hc->rh);

        return EOK;
}

/**
 * Used only when polling. Shall supplement the irq_commands.
 */
int hc_status(bus_t *bus, uint32_t *status)
{
        xhci_hc_t *hc = bus_to_hc(bus);
        int ip = XHCI_REG_RD(hc->rt_regs->ir, XHCI_INTR_IP);
        if (ip) {
                *status = XHCI_REG_RD(hc->op_regs, XHCI_OP_STATUS);
                XHCI_REG_WR(hc->op_regs, XHCI_OP_STATUS, *status & XHCI_STATUS_ACK_MASK);
                XHCI_REG_WR(hc->rt_regs->ir, XHCI_INTR_IP, 1);

                /* interrupt handler expects status from irq_commands, which is
                 * in xhci order. */
                *status = host2xhci(32, *status);
        }

        usb_log_debug2("Polled status: %x", *status);
        return EOK;
}

static int xhci_handle_mfindex_wrap_event(xhci_hc_t *hc, xhci_trb_t *trb)
{
        struct timeval tv;
        getuptime(&tv);
        usb_log_debug2("Microframe index wrapped (@%lu.%li, %"PRIu64" total).", tv.tv_sec, tv.tv_usec, hc->wrap_count);
        hc->wrap_time = ((uint64_t) tv.tv_sec) * 1000000 + ((uint64_t) tv.tv_usec);
        ++hc->wrap_count;
        return EOK;
}

static int handle_port_status_change_event(xhci_hc_t *hc, xhci_trb_t *trb)
{
        uint8_t port_id = XHCI_QWORD_EXTRACT(trb->parameter, 31, 24);
        usb_log_debug("Port status change event detected for port %u.", port_id);
        xhci_rh_handle_port_change(&hc->rh, port_id);
        return EOK;
}

typedef int (*event_handler) (xhci_hc_t *, xhci_trb_t *trb);

/**
 * These events are handled by separate event handling fibril.
 */
static event_handler event_handlers [] = {
        [XHCI_TRB_TYPE_PORT_STATUS_CHANGE_EVENT] = &handle_port_status_change_event,
        [XHCI_TRB_TYPE_TRANSFER_EVENT] = &xhci_handle_transfer_event,
};

/**
 * These events are handled directly in the interrupt handler, thus they must
 * not block waiting for another interrupt.
 */
static event_handler event_handlers_fast [] = {
        [XHCI_TRB_TYPE_COMMAND_COMPLETION_EVENT] = &xhci_handle_command_completion,
        [XHCI_TRB_TYPE_MFINDEX_WRAP_EVENT] = &xhci_handle_mfindex_wrap_event,
};

static int hc_handle_event(xhci_hc_t *hc, xhci_trb_t *trb)
{
        const unsigned type = TRB_TYPE(*trb);

        if (type <= ARRAY_SIZE(event_handlers_fast) && event_handlers_fast[type])
                return event_handlers_fast[type](hc, trb);

        if (type <= ARRAY_SIZE(event_handlers) && event_handlers[type])
                return xhci_sw_ring_enqueue(&hc->sw_ring, trb);

        return ENOTSUP;
}

static int event_worker(void *arg)
{
        int err;
        xhci_trb_t trb;
        xhci_hc_t * const hc = arg;
        assert(hc);

        while (xhci_sw_ring_dequeue(&hc->sw_ring, &trb) != EINTR) {
                const unsigned type = TRB_TYPE(trb);

                if ((err = event_handlers[type](hc, &trb)))
                        usb_log_error("Failed to handle event: %s", str_error(err));
        }

        // TODO: completion_complete
        fibril_mutex_lock(&hc->event_fibril_completion.guard);
        hc->event_fibril_completion.active = false;
        fibril_condvar_wait(&hc->event_fibril_completion.cv, &hc->event_fibril_completion.guard);
        fibril_mutex_unlock(&hc->event_fibril_completion.guard);

        return EOK;
}

/**
 * Dequeue from event ring and handle dequeued events.
 *
 * As there can be events, that blocks on waiting for subsequent events,
 * we solve this problem by first copying the event TRBs from the event ring,
 * then asserting EHB and only after, handling the events.
 *
 * Whenever the event handling blocks, it switches fibril, and incoming
 * IPC notification will create new event handling fibril for us.
 */
static void hc_run_event_ring(xhci_hc_t *hc, xhci_event_ring_t *event_ring, xhci_interrupter_regs_t *intr)
{
        int err;

        xhci_trb_t trb;
        hc->event_handler = fibril_get_id();

        while ((err = xhci_event_ring_dequeue(event_ring, &trb)) != ENOENT) {
                if ((err = hc_handle_event(hc, &trb)) != EOK) {
                        usb_log_error("Failed to handle event in interrupt: %s", str_error(err));
                }

                uint64_t erdp = hc->event_ring.dequeue_ptr;
                XHCI_REG_WR(intr, XHCI_INTR_ERDP_LO, LOWER32(erdp));
                XHCI_REG_WR(intr, XHCI_INTR_ERDP_HI, UPPER32(erdp));
        }

        hc->event_handler = 0;

        /* Update the ERDP to make room in the ring. */
        uint64_t erdp = hc->event_ring.dequeue_ptr;
        erdp |= XHCI_REG_MASK(XHCI_INTR_ERDP_EHB);
        XHCI_REG_WR(intr, XHCI_INTR_ERDP_LO, LOWER32(erdp));
        XHCI_REG_WR(intr, XHCI_INTR_ERDP_HI, UPPER32(erdp));

        usb_log_debug2("Event ring run finished.");
}

/**
 * Handle an interrupt request from xHC. Resolve all situations that trigger an
 * interrupt separately.
 *
 * Note that all RW1C bits in USBSTS register are cleared at the time of
 * handling the interrupt in irq_code. This method is the top-half.
 *
 * @param status contents of USBSTS register at the time of the interrupt.
 */
void hc_interrupt(bus_t *bus, uint32_t status)
{
        xhci_hc_t *hc = bus_to_hc(bus);
        status = xhci2host(32, status);

        if (status & XHCI_REG_MASK(XHCI_OP_HSE)) {
                usb_log_error("Host controller error occured. Bad things gonna happen...");
                status &= ~XHCI_REG_MASK(XHCI_OP_HSE);
        }

        if (status & XHCI_REG_MASK(XHCI_OP_EINT)) {
                usb_log_debug2("Event interrupt, running the event ring.");
                hc_run_event_ring(hc, &hc->event_ring, &hc->rt_regs->ir[0]);
                status &= ~XHCI_REG_MASK(XHCI_OP_EINT);
        }

        if (status & XHCI_REG_MASK(XHCI_OP_SRE)) {
                usb_log_error("Save/Restore error occured. WTF, S/R mechanism not implemented!");
                status &= ~XHCI_REG_MASK(XHCI_OP_SRE);
        }

        /* According to Note on p. 302, we may safely ignore the PCD bit. */
        status &= ~XHCI_REG_MASK(XHCI_OP_PCD);

        if (status) {
                usb_log_error("Non-zero status after interrupt handling (%08x) - missing something?", status);
        }
}

/**
 * Tear down all in-memory structures.
 */
void hc_fini(xhci_hc_t *hc)
{
        xhci_sw_ring_stop(&hc->sw_ring);

        // TODO: completion_wait
        fibril_mutex_lock(&hc->event_fibril_completion.guard);
        while (hc->event_fibril_completion.active)
                fibril_condvar_wait(&hc->event_fibril_completion.cv, &hc->event_fibril_completion.guard);
        fibril_mutex_unlock(&hc->event_fibril_completion.guard);
        xhci_sw_ring_fini(&hc->sw_ring);

        xhci_bus_fini(&hc->bus);
        xhci_event_ring_fini(&hc->event_ring);
        xhci_scratchpad_free(hc);
        dma_buffer_free(&hc->dcbaa_dma);
        xhci_fini_commands(hc);
        xhci_rh_fini(&hc->rh);
        pio_disable(hc->reg_base, RNGSZ(hc->mmio_range));
        usb_log_info("Finalized.");
}

/**
 * Ring a xHC Doorbell. Implements section 4.7.
 */
void hc_ring_doorbell(xhci_hc_t *hc, unsigned doorbell, unsigned target)
{
        assert(hc);
        uint32_t v = host2xhci(32, target & BIT_RRANGE(uint32_t, 7));
        pio_write_32(&hc->db_arry[doorbell], v);
        usb_log_debug2("Ringing doorbell %d (target: %d)", doorbell, target);
}

/**
 * Issue an Enable Slot command. Allocate memory for the slot and fill the
 * DCBAA with the newly created slot.
 */
int hc_enable_slot(xhci_device_t *dev)
{
        int err;
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);

        /* Prepare memory for the context */
        if ((err = dma_buffer_alloc(&dev->dev_ctx, sizeof(xhci_device_ctx_t))))
                return err;
        memset(dev->dev_ctx.virt, 0, sizeof(xhci_device_ctx_t));

        /* Get the slot number */
        xhci_cmd_t cmd;
        xhci_cmd_init(&cmd, XHCI_CMD_ENABLE_SLOT);

        err = xhci_cmd_sync(hc, &cmd);

        /* Link them together */
        if (err == EOK) {
                dev->slot_id = cmd.slot_id;
                hc->dcbaa[dev->slot_id] = host2xhci(64, dev->dev_ctx.phys);
        }

        xhci_cmd_fini(&cmd);
        return err;
}

/**
 * Issue a Disable Slot command for a slot occupied by device.
 * Frees the device context.
 */
int hc_disable_slot(xhci_device_t *dev)
{
        int err;
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);

        if ((err = xhci_cmd_sync_inline(hc, DISABLE_SLOT, .slot_id = dev->slot_id))) {
                return err;
        }

        /* Free the device context. */
        hc->dcbaa[dev->slot_id] = 0;
        dma_buffer_free(&dev->dev_ctx);

        /* Mark the slot as invalid. */
        dev->slot_id = 0;

        return EOK;
}

/**
 * Fill a slot context that is part of an Input Context with appropriate
 * values.
 *
 * @param ctx Slot context, zeroed out.
 */
static void xhci_setup_slot_context(xhci_device_t *dev, xhci_slot_ctx_t *ctx)
{
        /* Initialize slot_ctx according to section 4.3.3 point 3. */
        XHCI_SLOT_ROOT_HUB_PORT_SET(*ctx, dev->rh_port);
        XHCI_SLOT_ROUTE_STRING_SET(*ctx, dev->route_str);
        XHCI_SLOT_SPEED_SET(*ctx, usb_speed_to_psiv[dev->base.speed]);

        /*
         * Note: This function is used even before this flag can be set, to
         *       issue the address device command. It is OK, because these
         *       flags are not required to be valid for that command.
         */
        if (dev->is_hub) {
                XHCI_SLOT_HUB_SET(*ctx, 1);
                XHCI_SLOT_NUM_PORTS_SET(*ctx, dev->num_ports);
                XHCI_SLOT_TT_THINK_TIME_SET(*ctx, dev->tt_think_time);
                XHCI_SLOT_MTT_SET(*ctx, 0); // MTT not supported yet
        }

        /* Setup Transaction Translation. TODO: Test this with HS hub. */
        if (dev->base.tt.dev != NULL) {
                xhci_device_t *hub = xhci_device_get(dev->base.tt.dev);
                XHCI_SLOT_TT_HUB_SLOT_ID_SET(*ctx, hub->slot_id);
                XHCI_SLOT_TT_HUB_PORT_SET(*ctx, dev->base.tt.port);
        }

        // As we always allocate space for whole input context, we can set this to maximum
        XHCI_SLOT_CTX_ENTRIES_SET(*ctx, 31);
}

/**
 * Prepare an empty Endpoint Input Context inside a dma buffer.
 */
static int create_configure_ep_input_ctx(xhci_device_t *dev, dma_buffer_t *dma_buf)
{
        const int err = dma_buffer_alloc(dma_buf, sizeof(xhci_input_ctx_t));
        if (err)
                return err;

        xhci_input_ctx_t *ictx = dma_buf->virt;
        memset(ictx, 0, sizeof(xhci_input_ctx_t));

        // Quoting sec. 4.6.5 and 4.6.6: A1, D0, D1 are down (already zeroed), A0 is up.
        XHCI_INPUT_CTRL_CTX_ADD_SET(ictx->ctrl_ctx, 0);
        xhci_setup_slot_context(dev, &ictx->slot_ctx);

        return EOK;
}

/**
 * Initialize a device, assigning it an address. Implements section 4.3.4.
 *
 * @param dev Device to assing an address (unconfigured yet)
 * @param ep0 EP0 of device TODO remove, can be fetched from dev
 */
int hc_address_device(xhci_device_t *dev, xhci_endpoint_t *ep0)
{
        int err = ENOMEM;
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);

        /* Although we have the precise PSIV value on devices of tier 1,
         * we have to rely on reverse mapping on others. */
        if (!usb_speed_to_psiv[dev->base.speed]) {
                usb_log_error("Device reported an USB speed (%s) that cannot be mapped to HC port speed.", usb_str_speed(dev->base.speed));
                return EINVAL;
        }

        /* Issue configure endpoint command (sec 4.3.5). */
        dma_buffer_t ictx_dma_buf;
        if ((err = create_configure_ep_input_ctx(dev, &ictx_dma_buf)))
                return err;
        xhci_input_ctx_t *ictx = ictx_dma_buf.virt;

        /* Copy endpoint 0 context and set A1 flag. */
        XHCI_INPUT_CTRL_CTX_ADD_SET(ictx->ctrl_ctx, 1);
        xhci_setup_endpoint_context(ep0, &ictx->endpoint_ctx[0]);

        /* Address device needs Ctx entries set to 1 only */
        xhci_slot_ctx_t *slot_ctx = &ictx->slot_ctx;
        XHCI_SLOT_CTX_ENTRIES_SET(*slot_ctx, 1);

        /* Issue Address Device command. */
        if ((err = xhci_cmd_sync_inline(hc, ADDRESS_DEVICE, .slot_id = dev->slot_id, .input_ctx = ictx_dma_buf)))
                return err;

        xhci_device_ctx_t *dev_ctx = dev->dev_ctx.virt;
        dev->base.address = XHCI_SLOT_DEVICE_ADDRESS(dev_ctx->slot_ctx);
        usb_log_debug2("Obtained USB address: %d.", dev->base.address);

        return EOK;
}

/**
 * Issue a Configure Device command for a device in slot.
 *
 * @param slot_id Slot ID assigned to the device.
 */
int hc_configure_device(xhci_device_t *dev)
{
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);

        /* Issue configure endpoint command (sec 4.3.5). */
        dma_buffer_t ictx_dma_buf;
        const int err = create_configure_ep_input_ctx(dev, &ictx_dma_buf);
        if (err)
                return err;

        return xhci_cmd_sync_inline(hc, CONFIGURE_ENDPOINT, .slot_id = dev->slot_id, .input_ctx = ictx_dma_buf);
}

/**
 * Issue a Deconfigure Device command for a device in slot.
 *
 * @param dev The owner of the device
 */
int hc_deconfigure_device(xhci_device_t *dev)
{
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);

        /* Issue configure endpoint command (sec 4.3.5) with the DC flag. */
        return xhci_cmd_sync_inline(hc, CONFIGURE_ENDPOINT, .slot_id = dev->slot_id, .deconfigure = true);
}

/**
 * Instruct xHC to add an endpoint with supplied endpoint context.
 *
 * @param dev The owner of the device
 * @param ep_idx Endpoint DCI in question
 * @param ep_ctx Endpoint context of the endpoint
 */
int hc_add_endpoint(xhci_device_t *dev, uint8_t ep_idx, xhci_ep_ctx_t *ep_ctx)
{
        /* Issue configure endpoint command (sec 4.3.5). */
        dma_buffer_t ictx_dma_buf;
        const int err = create_configure_ep_input_ctx(dev, &ictx_dma_buf);
        if (err)
                return err;

        xhci_input_ctx_t *ictx = ictx_dma_buf.virt;
        XHCI_INPUT_CTRL_CTX_ADD_SET(ictx->ctrl_ctx, ep_idx + 1); /* Preceded by slot ctx */
        memcpy(&ictx->endpoint_ctx[ep_idx], ep_ctx, sizeof(xhci_ep_ctx_t));

        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);
        return xhci_cmd_sync_inline(hc, CONFIGURE_ENDPOINT, .slot_id = dev->slot_id, .input_ctx = ictx_dma_buf);
}

/**
 * Instruct xHC to drop an endpoint.
 *
 * @param dev The owner of the endpoint
 * @param ep_idx Endpoint DCI in question
 */
int hc_drop_endpoint(xhci_device_t *dev, uint8_t ep_idx)
{
        /* Issue configure endpoint command (sec 4.3.5). */
        dma_buffer_t ictx_dma_buf;
        const int err = create_configure_ep_input_ctx(dev, &ictx_dma_buf);
        if (err)
                return err;

        xhci_input_ctx_t *ictx = ictx_dma_buf.virt;
        XHCI_INPUT_CTRL_CTX_DROP_SET(ictx->ctrl_ctx, ep_idx + 1); /* Preceded by slot ctx */

        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);
        return xhci_cmd_sync_inline(hc, CONFIGURE_ENDPOINT, .slot_id = dev->slot_id, .input_ctx = ictx_dma_buf);
}

/**
 * Instruct xHC to update information about an endpoint, using supplied
 * endpoint context.
 *
 * @param dev The owner of the endpoint
 * @param ep_idx Endpoint DCI in question
 * @param ep_ctx Endpoint context of the endpoint
 */
int hc_update_endpoint(xhci_device_t *dev, uint8_t ep_idx, xhci_ep_ctx_t *ep_ctx)
{
        dma_buffer_t ictx_dma_buf;
        const int err = dma_buffer_alloc(&ictx_dma_buf, sizeof(xhci_input_ctx_t));
        if (err)
                return err;

        xhci_input_ctx_t *ictx = ictx_dma_buf.virt;
        memset(ictx, 0, sizeof(xhci_input_ctx_t));

        XHCI_INPUT_CTRL_CTX_ADD_SET(ictx->ctrl_ctx, ep_idx + 1);
        memcpy(&ictx->endpoint_ctx[ep_idx], ep_ctx, sizeof(xhci_ep_ctx_t));

        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);
        return xhci_cmd_sync_inline(hc, EVALUATE_CONTEXT, .slot_id = dev->slot_id, .input_ctx = ictx_dma_buf);
}

/**
 * Instruct xHC to stop running a transfer ring on an endpoint.
 *
 * @param dev The owner of the endpoint
 * @param ep_idx Endpoint DCI in question
 */
int hc_stop_endpoint(xhci_device_t *dev, uint8_t ep_idx)
{
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);
        return xhci_cmd_sync_inline(hc, STOP_ENDPOINT, .slot_id = dev->slot_id, .endpoint_id = ep_idx);
}

/**
 * Instruct xHC to reset halted endpoint.
 *
 * @param dev The owner of the endpoint
 * @param ep_idx Endpoint DCI in question
 */
int hc_reset_endpoint(xhci_device_t *dev, uint8_t ep_idx)
{
        xhci_hc_t * const hc = bus_to_hc(dev->base.bus);
        return xhci_cmd_sync_inline(hc, RESET_ENDPOINT, .slot_id = dev->slot_id, .endpoint_id = ep_idx);
}

/**
 * @}
 */