source: mainline/uspace/drv/bus/usb/xhci/hc.c@ dcf0597

/*
 * 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/utils/malloc32.h>
#include "debug.h"
#include "hc.h"
#include "rh.h"
#include "hw_struct/trb.h"
#include "commands.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(mjr, psie, psim) { \
        .name = "USB ", \
        .major = mjr, \
        .minor = 0, \
        .rx_bps = PSI_TO_BPS(psie, psim), \
        .tx_bps = PSI_TO_BPS(psie, psim) \
}
static const xhci_port_speed_t ps_default_full  = PORT_SPEED(2, 2, 12);
static const xhci_port_speed_t ps_default_low   = PORT_SPEED(2, 1, 1500);
static const xhci_port_speed_t ps_default_high  = PORT_SPEED(2, 2, 480);
static const xhci_port_speed_t ps_default_super = PORT_SPEED(3, 3, 5);

/**
 * Walk the list of extended capabilities.
 */
static int hc_parse_ec(xhci_hc_t *hc)
{
        unsigned psic, major, minor;
        xhci_sp_name_t name;

        xhci_port_speed_t *speeds = hc->rh.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;
                        }

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

                                if (major == 2) {
                                        speeds[1] = ps_default_full;
                                        speeds[2] = ps_default_low;
                                        speeds[3] = ps_default_high;
                                } else if (major == 3) {
                                        speeds[4] = ps_default_super;
                                } 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);

                                        speeds[psiv].major = major;
                                        speeds[psiv].minor = minor;
                                        str_ncpy(speeds[psiv].name, 4, name.str, 4);

                                        uint64_t bps = PSI_TO_BPS(psie, psim);

                                        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;
}

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.\n",
            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->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);

        if ((err = hc_parse_ec(hc))) {
                pio_disable(hc->base, RNGSZ(hc->mmio_range));
                return err;
        }

        return EOK;
}

int hc_init_memory(xhci_hc_t *hc)
{
        int err;

        hc->dcbaa = malloc32((1 + hc->max_slots) * sizeof(uint64_t));
        if (!hc->dcbaa)
                return ENOMEM;

        hc->dcbaa_virt = malloc((1 + hc->max_slots) * sizeof(xhci_virt_device_ctx_t));
        if (!hc->dcbaa_virt) {
                err = ENOMEM;
                goto err_dcbaa;
        }

        if ((err = xhci_trb_ring_init(&hc->command_ring, hc)))
                goto err_dcbaa_virt;

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

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

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

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

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


        return EOK;

err_rh:
        xhci_rh_fini(&hc->rh);
err_cmd:
        xhci_fini_commands(hc);
err_scratch:
        xhci_scratchpad_free(hc);
err_event_ring:
        xhci_event_ring_fini(&hc->event_ring);
err_cmd_ring:
        xhci_trb_ring_fini(&hc->command_ring);
err_dcbaa_virt:
        free32(hc->dcbaa_virt);
err_dcbaa:
        free32(hc->dcbaa);
        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];
}

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;

        /* Section 4.22.1 */
        /* TODO: Test this with USB3-aware BIOS */
        usb_log_debug2("LEGSUP: bios: %x, os: %x", hc->legsup->sem_bios, hc->legsup->sem_os);
        XHCI_REG_WR(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) {
                        assert(XHCI_REG_RD(hc->legsup, XHCI_LEGSUP_SEM_OS) == 1);
                        return EOK;
                }
                async_usleep(XHCI_LEGSUP_POLLING_DELAY_1MS);
        }
        usb_log_error("BIOS did not release XHCI legacy hold!\n");

        return ENOTSUP;
}

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

        /* Wait 16 ms until the HC is halted */
        async_usleep(16000);
        assert(XHCI_REG_RD(hc->op_regs, XHCI_OP_HCH));

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

        /* Wait until the reset is complete */
        while (XHCI_REG_RD(hc->op_regs, XHCI_OP_HCRST))
                async_usleep(1000);

        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;

        while (XHCI_REG_RD(hc->op_regs, XHCI_OP_CNR))
                async_usleep(1000);

        uint64_t dcbaaptr = addr_to_phys(hc->dcbaa);
        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, 0);

        uint64_t crptr = xhci_trb_ring_get_dequeue_ptr(&hc->command_ring);
        XHCI_REG_WR(hc->op_regs, XHCI_OP_CRCR_LO, LOWER32(crptr) >> 6);
        XHCI_REG_WR(hc->op_regs, XHCI_OP_CRCR_HI, UPPER32(crptr));

        uint64_t erstptr = addr_to_phys(hc->event_ring.erst);
        uint64_t erdp = hc->event_ring.dequeue_ptr;
        xhci_interrupter_regs_t *intr0 = &hc->rt_regs->ir[0];
        XHCI_REG_WR(intr0, XHCI_INTR_ERSTSZ, hc->event_ring.segment_count);
        XHCI_REG_WR(intr0, XHCI_INTR_ERDP_LO, LOWER32(erdp));
        XHCI_REG_WR(intr0, XHCI_INTR_ERDP_HI, UPPER32(erdp));
        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_RS, 1);

        /* The reset changed status of all ports, and SW originated reason does
         * not cause an interrupt.
         */
        xhci_rh_handle_port_change(&hc->rh);

        return EOK;
}

/**
 * Used only when polling. Shall supplement the irq_commands.
 */
int hc_status(xhci_hc_t *hc, uint32_t *status)
{
        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("HC(%p): Polled status: %x", hc, *status);
        return EOK;
}

int hc_schedule(xhci_hc_t *hc, usb_transfer_batch_t *batch)
{
        assert(batch);

        usb_log_debug2("EP(%d:%d) started %s transfer of size %lu.",
                batch->ep->target.address, batch->ep->target.endpoint,
                usb_str_transfer_type(batch->ep->transfer_type),
                batch->buffer_size);

        if (!batch->ep->target.address) {
                usb_log_error("Attempted to schedule transfer to address 0.");
                return EINVAL;
        }

        switch (batch->ep->transfer_type) {
        case USB_TRANSFER_CONTROL:
                return xhci_schedule_control_transfer(hc, batch);
        case USB_TRANSFER_ISOCHRONOUS:
                /* TODO: Implement me. */
                break;
        case USB_TRANSFER_BULK:
                return xhci_schedule_bulk_transfer(hc, batch);
        case USB_TRANSFER_INTERRUPT:
                /* TODO: Implement me. */
                break;
        }

        return EOK;
}

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

static event_handler event_handlers [] = {
        [XHCI_TRB_TYPE_COMMAND_COMPLETION_EVENT] = &xhci_handle_command_completion,
        [XHCI_TRB_TYPE_PORT_STATUS_CHANGE_EVENT] = &xhci_rh_handle_port_status_change_event,
        [XHCI_TRB_TYPE_TRANSFER_EVENT] = &xhci_handle_transfer_event,
};

static int hc_handle_event(xhci_hc_t *hc, xhci_trb_t *trb, xhci_interrupter_regs_t *intr)
{
        unsigned type = TRB_TYPE(*trb);
        if (type >= ARRAY_SIZE(event_handlers) || !event_handlers[type])
                return ENOTSUP;

        return event_handlers[type](hc, trb);
}

static void hc_run_event_ring(xhci_hc_t *hc, xhci_event_ring_t *event_ring, xhci_interrupter_regs_t *intr)
{
        int err;
        ssize_t size = 16;
        xhci_trb_t *queue = malloc(sizeof(xhci_trb_t) * size);
        if (!queue) {
                usb_log_error("Not enough memory to run the event ring.");
                return;
        }

        xhci_trb_t *head = queue;

        while ((err = xhci_event_ring_dequeue(event_ring, head)) != ENOENT) {
                if (err != EOK) {
                        usb_log_warning("Error while accessing event ring: %s", str_error(err));
                        break;
                }

                usb_log_debug2("Dequeued trb from event ring: %s", xhci_trb_str_type(TRB_TYPE(*head)));
                head++;

                /* Expand the array if needed. */
                if (head - queue >= size) {
                        size *= 2;
                        xhci_trb_t *new_queue = realloc(queue, size);
                        if (new_queue == NULL)
                                break; /* Will process only those TRBs we have memory for. */

                        head = new_queue + (head - queue);
                }
        }

        /* Update the ERDP to make room in the ring. */
        usb_log_debug2("Copying from ring finished, updating ERDP.");
        hc->event_ring.dequeue_ptr = host2xhci(64, addr_to_phys(hc->event_ring.dequeue_trb));
        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));
        XHCI_REG_SET(intr, XHCI_INTR_ERDP_EHB, 1);

        /* Handle all of the collected events if possible. */
        if (head == queue)
                usb_log_warning("No events to be handled!");

        for (xhci_trb_t *tail = queue; tail != head; tail++) {
                if ((err = hc_handle_event(hc, tail, intr)) != EOK) {
                        usb_log_error("Failed to handle event: %s", str_error(err));
                }
        }

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

void hc_interrupt(xhci_hc_t *hc, uint32_t status)
{
        status = xhci2host(32, status);

        if (status & XHCI_REG_MASK(XHCI_OP_PCD)) {
                usb_log_debug2("Root hub interrupt.");
                xhci_rh_handle_port_change(&hc->rh);
                status &= ~XHCI_REG_MASK(XHCI_OP_PCD);
        }

        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);
        }

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

static void hc_dcbaa_fini(xhci_hc_t *hc)
{
        xhci_trb_ring_t* trb_ring;
        xhci_scratchpad_free(hc);

        /* Idx 0 already deallocated by xhci_scratchpad_free. */
        for (unsigned i = 1; i < hc->max_slots + 1; ++i) {
                if (hc->dcbaa_virt[i].dev_ctx) {
                        free32(hc->dcbaa_virt[i].dev_ctx);
                        hc->dcbaa_virt[i].dev_ctx = NULL;
                }

                for (unsigned i = 0; i < XHCI_EP_COUNT; ++i) {
                        trb_ring = hc->dcbaa_virt[i].trs[i];
                        if (trb_ring) {
                                hc->dcbaa_virt[i].trs[i] = NULL;
                                xhci_trb_ring_fini(trb_ring);
                                free32(trb_ring);
                        }
                }
        }

        free32(hc->dcbaa);
        free32(hc->dcbaa_virt);
}

void hc_fini(xhci_hc_t *hc)
{
        xhci_bus_fini(&hc->bus);
        xhci_trb_ring_fini(&hc->command_ring);
        xhci_event_ring_fini(&hc->event_ring);
        hc_dcbaa_fini(hc);
        xhci_fini_commands(hc);
        xhci_rh_fini(&hc->rh);
        pio_disable(hc->base, RNGSZ(hc->mmio_range));
        usb_log_info("HC(%p): Finalized.", hc);
}

int 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);
        return EOK;
}

/**
 * @}
 */