source: mainline/uspace/drv/block/ata_bd/ata_bd.c@ 132ab5d1

/*
 * Copyright (c) 2013 Jiri Svoboda
 * 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 bd
 * @{
 */

/**
 * @file
 * @brief ATA disk driver
 *
 * This driver supports CHS, 28-bit and 48-bit LBA addressing, as well as
 * PACKET devices. It only uses PIO transfers. There is no support DMA
 * or any other fancy features such as S.M.A.R.T, removable devices, etc.
 *
 * This driver is based on the ATA-1, ATA-2, ATA-3 and ATA/ATAPI-4 through 7
 * standards, as published by the ANSI, NCITS and INCITS standards bodies,
 * which are freely available. This driver contains no vendor-specific
 * code at this moment.
 *
 * The driver services a single controller which can have up to two disks
 * attached.
 */

#include <ddi.h>
#include <ddf/log.h>
#include <async.h>
#include <as.h>
#include <bd_srv.h>
#include <fibril_synch.h>
#include <scsi/mmc.h>
#include <scsi/sbc.h>
#include <scsi/spc.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stddef.h>
#include <str.h>
#include <inttypes.h>
#include <errno.h>
#include <byteorder.h>
#include <macros.h>

#include "ata_hw.h"
#include "ata_bd.h"
#include "main.h"

#define NAME       "ata_bd"

/** Number of defined legacy controller base addresses. */
#define LEGACY_CTLS 4

/**
 * Size of data returned from Identify Device or Identify Packet Device
 * command.
 */
static const size_t identify_data_size = 512;

static int ata_bd_init_io(ata_ctrl_t *ctrl);
static void ata_bd_fini_io(ata_ctrl_t *ctrl);

static int ata_bd_open(bd_srvs_t *, bd_srv_t *);
static int ata_bd_close(bd_srv_t *);
static int ata_bd_read_blocks(bd_srv_t *, uint64_t ba, size_t cnt, void *buf,
    size_t);
static int ata_bd_read_toc(bd_srv_t *, uint8_t session, void *buf, size_t);
static int ata_bd_write_blocks(bd_srv_t *, uint64_t ba, size_t cnt,
    const void *buf, size_t);
static int ata_bd_get_block_size(bd_srv_t *, size_t *);
static int ata_bd_get_num_blocks(bd_srv_t *, aoff64_t *);
static int ata_bd_sync_cache(bd_srv_t *, aoff64_t, size_t);

static int ata_rcmd_read(disk_t *disk, uint64_t ba, size_t cnt,
    void *buf);
static int ata_rcmd_write(disk_t *disk, uint64_t ba, size_t cnt,
    const void *buf);
static int ata_rcmd_flush_cache(disk_t *disk);
static int disk_init(ata_ctrl_t *ctrl, disk_t *d, int disk_id);
static int ata_identify_dev(disk_t *disk, void *buf);
static int ata_identify_pkt_dev(disk_t *disk, void *buf);
static int ata_cmd_packet(disk_t *disk, const void *cpkt, size_t cpkt_size,
    void *obuf, size_t obuf_size, size_t *rcvd_size);
static int ata_pcmd_inquiry(disk_t *disk, void *obuf, size_t obuf_size,
    size_t *rcvd_size);
static int ata_pcmd_read_12(disk_t *disk, uint64_t ba, size_t cnt,
    void *obuf, size_t obuf_size);
static int ata_pcmd_read_capacity(disk_t *disk, uint64_t *nblocks,
    size_t *block_size);
static int ata_pcmd_read_toc(disk_t *disk, uint8_t ses,
    void *obuf, size_t obuf_size);
static void disk_print_summary(disk_t *d);
static int coord_calc(disk_t *d, uint64_t ba, block_coord_t *bc);
static void coord_sc_program(ata_ctrl_t *ctrl, const block_coord_t *bc,
    uint16_t scnt);
static int wait_status(ata_ctrl_t *ctrl, unsigned set, unsigned n_reset,
    uint8_t *pstatus, unsigned timeout);

bd_ops_t ata_bd_ops = {
        .open = ata_bd_open,
        .close = ata_bd_close,
        .read_blocks = ata_bd_read_blocks,
        .read_toc = ata_bd_read_toc,
        .write_blocks = ata_bd_write_blocks,
        .get_block_size = ata_bd_get_block_size,
        .get_num_blocks = ata_bd_get_num_blocks,
        .sync_cache = ata_bd_sync_cache
};

static disk_t *bd_srv_disk(bd_srv_t *bd)
{
        return (disk_t *)bd->srvs->sarg;
}

static int disk_dev_idx(disk_t *disk)
{
        return (disk->disk_id & 1);
}

/** Initialize ATA controller. */
int ata_ctrl_init(ata_ctrl_t *ctrl, ata_base_t *res)
{
        int i;
        int rc;
        int n_disks;

        ddf_msg(LVL_DEBUG, "ata_ctrl_init()");

        fibril_mutex_initialize(&ctrl->lock);
        ctrl->cmd_physical = res->cmd;
        ctrl->ctl_physical = res->ctl;

        ddf_msg(LVL_NOTE, "I/O address %p/%p", (void *) ctrl->cmd_physical,
            (void *) ctrl->ctl_physical);

        rc = ata_bd_init_io(ctrl);
        if (rc != EOK)
                return rc;

        for (i = 0; i < MAX_DISKS; i++) {
                ddf_msg(LVL_NOTE, "Identify drive %d...", i);

                rc = disk_init(ctrl, &ctrl->disk[i], i);

                if (rc == EOK) {
                        disk_print_summary(&ctrl->disk[i]);
                } else {
                        ddf_msg(LVL_NOTE, "Not found.");
                }
        }

        n_disks = 0;

        for (i = 0; i < MAX_DISKS; i++) {
                /* Skip unattached drives. */
                if (ctrl->disk[i].present == false)
                        continue;

                rc = ata_fun_create(&ctrl->disk[i]);
                if (rc != EOK) {
                        ddf_msg(LVL_ERROR, "Unable to create function for "
                            "disk %d.", i);
                        goto error;
                }
                ++n_disks;
        }

        if (n_disks == 0) {
                ddf_msg(LVL_WARN, "No disks detected.");
                rc = EIO;
                goto error;
        }

        return EOK;
error:
        for (i = 0; i < MAX_DISKS; i++) {
                if (ata_fun_remove(&ctrl->disk[i]) != EOK) {
                        ddf_msg(LVL_ERROR, "Unable to clean up function for "
                            "disk %d.", i);
                }
        }
        ata_bd_fini_io(ctrl);
        return rc;
}

/** Remove ATA controller. */
int ata_ctrl_remove(ata_ctrl_t *ctrl)
{
        int i;
        int rc;

        ddf_msg(LVL_DEBUG, ": ata_ctrl_remove()");

        fibril_mutex_lock(&ctrl->lock);

        for (i = 0; i < MAX_DISKS; i++) {
                rc = ata_fun_remove(&ctrl->disk[i]);
                if (rc != EOK) {
                        ddf_msg(LVL_ERROR, "Unable to clean up function for "
                            "disk %d.", i);
                        return rc;
                }
        }

        ata_bd_fini_io(ctrl);
        fibril_mutex_unlock(&ctrl->lock);

        return EOK;
}

/** Surprise removal of ATA controller. */
int ata_ctrl_gone(ata_ctrl_t *ctrl)
{
        int i;
        int rc;

        ddf_msg(LVL_DEBUG, "ata_ctrl_gone()");

        fibril_mutex_lock(&ctrl->lock);

        for (i = 0; i < MAX_DISKS; i++) {
                rc = ata_fun_unbind(&ctrl->disk[i]);
                if (rc != EOK) {
                        ddf_msg(LVL_ERROR, "Unable to clean up function for "
                            "disk %d.", i);
                        return rc;
                }
        }

        ata_bd_fini_io(ctrl);
        fibril_mutex_unlock(&ctrl->lock);

        return EOK;
}

/** Print one-line device summary. */
static void disk_print_summary(disk_t *d)
{
        uint64_t mbytes;
        char *atype = NULL;
        char *cap = NULL;
        int rc;

        if (d->dev_type == ata_reg_dev) {
                switch (d->amode) {
                case am_chs:
                        rc = asprintf(&atype, "CHS %u cylinders, %u heads, "
                            "%u sectors", d->geom.cylinders, d->geom.heads,
                            d->geom.sectors);
                        if (rc < 0) {
                                /* Out of memory */
                                atype = NULL;
                        }
                        break;
                case am_lba28:
                        atype = str_dup("LBA-28");
                        break;
                case am_lba48:
                        atype = str_dup("LBA-48");
                        break;
                }
        } else {
                atype = str_dup("PACKET");
        }

        if (atype == NULL)
                return;

        mbytes = d->blocks / (2 * 1024);
        if (mbytes > 0) {
                rc = asprintf(&cap, " %" PRIu64 " MB.", mbytes);
                if (rc < 0) {
                        cap = NULL;
                        goto cleanup;
                }
        }

        ddf_msg(LVL_NOTE, "%s: %s %" PRIu64 " blocks%s", d->model, atype,
            d->blocks, cap);
cleanup:
        free(atype);
        free(cap);
}

/** Enable device I/O. */
static int ata_bd_init_io(ata_ctrl_t *ctrl)
{
        int rc;
        void *vaddr;

        rc = pio_enable((void *) ctrl->cmd_physical, sizeof(ata_cmd_t), &vaddr);
        if (rc != EOK) {
                ddf_msg(LVL_ERROR, "Cannot initialize device I/O space.");
                return rc;
        }

        ctrl->cmd = vaddr;

        rc = pio_enable((void *) ctrl->ctl_physical, sizeof(ata_ctl_t), &vaddr);
        if (rc != EOK) {
                ddf_msg(LVL_ERROR, "Cannot initialize device I/O space.");
                return rc;
        }

        ctrl->ctl = vaddr;

        return EOK;
}

/** Clean up device I/O. */
static void ata_bd_fini_io(ata_ctrl_t *ctrl)
{
        (void) ctrl;
        /* XXX TODO */
}

/** Initialize a disk.
 *
 * Probes for a disk, determines its parameters and initializes
 * the disk structure.
 */
static int disk_init(ata_ctrl_t *ctrl, disk_t *d, int disk_id)
{
        identify_data_t idata;
        uint8_t model[40];
        scsi_std_inquiry_data_t inq_data;
        size_t isize;
        uint16_t w;
        uint8_t c;
        uint16_t bc;
        uint64_t nblocks;
        size_t block_size;
        size_t pos, len;
        int rc;
        unsigned i;

        d->ctrl = ctrl;
        d->disk_id = disk_id;
        d->present = false;
        d->afun = NULL;

        /* Try identify command. */
        rc = ata_identify_dev(d, &idata);
        if (rc == EOK) {
                /* Success. It's a register (non-packet) device. */
                ddf_msg(LVL_NOTE, "ATA register-only device found.");
                d->dev_type = ata_reg_dev;
        } else if (rc == EIO) {
                /*
                 * There is something, but not a register device. Check to see
                 * whether the IDENTIFY command left the packet signature in
                 * the registers in case this is a packet device.
                 *
                 * According to the ATA specification, the LBA low and
                 * interrupt reason registers should be set to 0x01. However,
                 * there are many devices that do not follow this and only set
                 * the byte count registers. So, only check these.
                 */
                bc = ((uint16_t)pio_read_8(&ctrl->cmd->cylinder_high) << 8) |
                    pio_read_8(&ctrl->cmd->cylinder_low);

                if (bc == PDEV_SIGNATURE_BC) {
                        rc = ata_identify_pkt_dev(d, &idata);
                        if (rc == EOK) {
                                /* We have a packet device. */
                                d->dev_type = ata_pkt_dev;
                        } else {
                                return EIO;
                        }
                } else {
                        /* Nope. Something's there, but not recognized. */
                        return EIO;
                }
        } else {
                /* Operation timed out. That means there is no device there. */
                return EIO;
        }

        if (d->dev_type == ata_pkt_dev) {
                /* Packet device */
                d->amode = 0;

                d->geom.cylinders = 0;
                d->geom.heads = 0;
                d->geom.sectors = 0;

                d->blocks = 0;
        } else if ((idata.caps & rd_cap_lba) == 0) {
                /* Device only supports CHS addressing. */
                d->amode = am_chs;

                d->geom.cylinders = idata.cylinders;
                d->geom.heads = idata.heads;
                d->geom.sectors = idata.sectors;

                d->blocks = d->geom.cylinders * d->geom.heads * d->geom.sectors;
        } else if ((idata.cmd_set1 & cs1_addr48) == 0) {
                /* Device only supports LBA-28 addressing. */
                d->amode = am_lba28;

                d->geom.cylinders = 0;
                d->geom.heads = 0;
                d->geom.sectors = 0;

                d->blocks =
                     (uint32_t) idata.total_lba28_0 | 
                    ((uint32_t) idata.total_lba28_1 << 16);
        } else {
                /* Device supports LBA-48 addressing. */
                d->amode = am_lba48;

                d->geom.cylinders = 0;
                d->geom.heads = 0;
                d->geom.sectors = 0;

                d->blocks =
                     (uint64_t) idata.total_lba48_0 |
                    ((uint64_t) idata.total_lba48_1 << 16) |
                    ((uint64_t) idata.total_lba48_2 << 32) | 
                    ((uint64_t) idata.total_lba48_3 << 48);
        }

        /*
         * Convert model name to string representation.
         */
        for (i = 0; i < 20; i++) {
                w = idata.model_name[i];
                model[2 * i] = w >> 8;
                model[2 * i + 1] = w & 0x00ff;
        }

        len = 40;
        while (len > 0 && model[len - 1] == 0x20)
                --len;

        pos = 0;
        for (i = 0; i < len; ++i) {
                c = model[i];
                if (c >= 0x80) c = '?';

                chr_encode(c, d->model, &pos, 40);
        }
        d->model[pos] = '\0';

        if (d->dev_type == ata_pkt_dev) {
                /* Send inquiry. */
                rc = ata_pcmd_inquiry(d, &inq_data, sizeof(inq_data), &isize);
                if (rc != EOK || isize < sizeof(inq_data)) {
                        ddf_msg(LVL_ERROR, "Device inquiry failed.");
                        d->present = false;
                        return EIO;
                }

                /* Check device type. */
                if (INQUIRY_PDEV_TYPE(inq_data.pqual_devtype) != SCSI_DEV_CD_DVD)
                        ddf_msg(LVL_WARN, "Peripheral device type is not CD-ROM.");

                rc = ata_pcmd_read_capacity(d, &nblocks, &block_size);
                if (rc != EOK) {
                        ddf_msg(LVL_ERROR, "Read capacity command failed.");
                        d->present = false;
                        return EIO;
                }

                d->blocks = nblocks;
                d->block_size = block_size;
        } else {
                /* Assume register Read always uses 512-byte blocks. */
                d->block_size = 512;
        }

        d->present = true;
        return EOK;
}

static int ata_bd_open(bd_srvs_t *bds, bd_srv_t *bd)
{
        return EOK;
}

static int ata_bd_close(bd_srv_t *bd)
{
        return EOK;
}

/** Read multiple blocks from the device. */
static int ata_bd_read_blocks(bd_srv_t *bd, uint64_t ba, size_t cnt,
    void *buf, size_t size)
{
        disk_t *disk = bd_srv_disk(bd);
        int rc;

        if (size < cnt * disk->block_size)
                return EINVAL;

        while (cnt > 0) {
                if (disk->dev_type == ata_reg_dev) {
                        rc = ata_rcmd_read(disk, ba, 1, buf);
                } else {
                        rc = ata_pcmd_read_12(disk, ba, 1, buf,
                            disk->block_size);
                }

                if (rc != EOK)
                        return rc;

                ++ba;
                --cnt;
                buf += disk->block_size;
        }

        return EOK;
}

/** Read TOC from device. */
static int ata_bd_read_toc(bd_srv_t *bd, uint8_t session, void *buf, size_t size)
{
        disk_t *disk = bd_srv_disk(bd);

        return ata_pcmd_read_toc(disk, session, buf, size);
}

/** Write multiple blocks to the device. */
static int ata_bd_write_blocks(bd_srv_t *bd, uint64_t ba, size_t cnt,
    const void *buf, size_t size)
{
        disk_t *disk = bd_srv_disk(bd);
        int rc;

        if (disk->dev_type != ata_reg_dev)
                return ENOTSUP;

        if (size < cnt * disk->block_size)
                return EINVAL;

        while (cnt > 0) {
                rc = ata_rcmd_write(disk, ba, 1, buf);
                if (rc != EOK)
                        return rc;

                ++ba;
                --cnt;
                buf += disk->block_size;
        }

        return EOK;
}

/** Get device block size. */
static int ata_bd_get_block_size(bd_srv_t *bd, size_t *rbsize)
{
        disk_t *disk = bd_srv_disk(bd);

        *rbsize = disk->block_size;
        return EOK;
}

/** Get device number of blocks. */
static int ata_bd_get_num_blocks(bd_srv_t *bd, aoff64_t *rnb)
{
        disk_t *disk = bd_srv_disk(bd);

        *rnb = disk->blocks;
        return EOK;
}

/** Flush cache. */
static int ata_bd_sync_cache(bd_srv_t *bd, uint64_t ba, size_t cnt)
{
        disk_t *disk = bd_srv_disk(bd);

        /* ATA cannot flush just some blocks, we just flush everything. */
        (void)ba;
        (void)cnt;

        return ata_rcmd_flush_cache(disk);
}

/** PIO data-in command protocol. */
static int ata_pio_data_in(disk_t *disk, void *obuf, size_t obuf_size,
    size_t blk_size, size_t nblocks)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint16_t data;
        size_t i;
        uint8_t status;

        /* XXX Support multiple blocks */
        assert(nblocks == 1);
        assert(blk_size % 2 == 0);

        if (wait_status(ctrl, 0, ~SR_BSY, &status, TIMEOUT_BSY) != EOK)
                return EIO;

        if ((status & SR_DRQ) != 0) {
                /* Read data from the device buffer. */

                for (i = 0; i < blk_size / 2; i++) {
                        data = pio_read_16(&ctrl->cmd->data_port);
                        ((uint16_t *) obuf)[i] = data;
                }
        }

        if ((status & SR_ERR) != 0)
                return EIO;

        return EOK;
}

/** PIO data-out command protocol. */
static int ata_pio_data_out(disk_t *disk, const void *buf, size_t buf_size,
    size_t blk_size, size_t nblocks)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        size_t i;
        uint8_t status;

        /* XXX Support multiple blocks */
        assert(nblocks == 1);
        assert(blk_size % 2 == 0);

        if (wait_status(ctrl, 0, ~SR_BSY, &status, TIMEOUT_BSY) != EOK)
                return EIO;

        if ((status & SR_DRQ) != 0) {
                /* Write data to the device buffer. */

                for (i = 0; i < blk_size / 2; i++) {
                        pio_write_16(&ctrl->cmd->data_port, ((uint16_t *) buf)[i]);
                }
        }

        if (status & SR_ERR)
                return EIO;

        return EOK;
}

/** PIO non-data command protocol. */
static int ata_pio_nondata(disk_t *disk)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint8_t status;

        if (wait_status(ctrl, 0, ~SR_BSY, &status, TIMEOUT_BSY) != EOK)
                return EIO;

        if (status & SR_ERR)
                return EIO;

        return EOK;
}

/** Issue IDENTIFY DEVICE command.
 *
 * Reads @c identify data into the provided buffer. This is used to detect
 * whether an ATA device is present and if so, to determine its parameters.
 *
 * @param disk          Disk
 * @param buf           Pointer to a 512-byte buffer.
 *
 * @return              ETIMEOUT on timeout (this can mean the device is
 *                      not present). EIO if device responds with error.
 */
static int ata_identify_dev(disk_t *disk, void *buf)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint8_t status;
        uint8_t drv_head;

        drv_head = ((disk_dev_idx(disk) != 0) ? DHR_DRV : 0);

        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK)
                return ETIMEOUT;

        pio_write_8(&ctrl->cmd->drive_head, drv_head);

        /*
         * Do not wait for DRDY to be set in case this is a packet device.
         * We determine whether the device is present by waiting for DRQ to be
         * set after issuing the command.
         */
        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK)
                return ETIMEOUT;

        pio_write_8(&ctrl->cmd->command, CMD_IDENTIFY_DRIVE);

        if (wait_status(ctrl, 0, ~SR_BSY, &status, TIMEOUT_PROBE) != EOK)
                return ETIMEOUT;

        /*
         * If ERR is set, this may be a packet device, so return EIO to cause
         * the caller to check for one.
         */
        if ((status & SR_ERR) != 0)
                return EIO;

        /*
         * For probing purposes we need to wait for some status bit to become
         * active - otherwise we could be fooled just by receiving all zeroes.
         */
        if (wait_status(ctrl, SR_DRQ, ~SR_BSY, &status, TIMEOUT_PROBE) != EOK)
                return ETIMEOUT;

        return ata_pio_data_in(disk, buf, identify_data_size,
            identify_data_size, 1);
}

/** Issue Identify Packet Device command.
 *
 * Reads @c identify data into the provided buffer. This is used to detect
 * whether an ATAPI device is present and if so, to determine its parameters.
 *
 * @param disk          Disk
 * @param buf           Pointer to a 512-byte buffer.
 */
static int ata_identify_pkt_dev(disk_t *disk, void *buf)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint8_t drv_head;

        drv_head = ((disk_dev_idx(disk) != 0) ? DHR_DRV : 0);

        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK)
                return EIO;

        pio_write_8(&ctrl->cmd->drive_head, drv_head);

        /* For ATAPI commands we do not need to wait for DRDY. */
        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK)
                return EIO;

        pio_write_8(&ctrl->cmd->command, CMD_IDENTIFY_PKT_DEV);

        return ata_pio_data_in(disk, buf, identify_data_size,
            identify_data_size, 1);
}

/** Issue packet command (i. e. write a command packet to the device).
 *
 * Only data-in commands are supported (e.g. inquiry, read).
 *
 * @param disk          Disk
 * @param obuf          Buffer for storing data read from device
 * @param obuf_size     Size of obuf in bytes
 * @param rcvd_size     Place to store number of bytes read or @c NULL
 *
 * @return EOK on success, EIO on error.
 */
static int ata_cmd_packet(disk_t *disk, const void *cpkt, size_t cpkt_size,
    void *obuf, size_t obuf_size, size_t *rcvd_size)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        size_t i;
        uint8_t status;
        uint8_t drv_head;
        size_t data_size;
        uint16_t val;

        fibril_mutex_lock(&ctrl->lock);

        /* New value for Drive/Head register */
        drv_head =
            ((disk_dev_idx(disk) != 0) ? DHR_DRV : 0);

        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_PROBE) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        pio_write_8(&ctrl->cmd->drive_head, drv_head);

        if (wait_status(ctrl, 0, ~(SR_BSY|SR_DRQ), NULL, TIMEOUT_BSY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        /* Byte count <- max. number of bytes we can read in one transfer. */
        pio_write_8(&ctrl->cmd->cylinder_low, 0xfe);
        pio_write_8(&ctrl->cmd->cylinder_high, 0xff);

        pio_write_8(&ctrl->cmd->command, CMD_PACKET);

        if (wait_status(ctrl, SR_DRQ, ~SR_BSY, &status, TIMEOUT_BSY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        /* Write command packet. */
        for (i = 0; i < (cpkt_size + 1) / 2; i++)
                pio_write_16(&ctrl->cmd->data_port, ((uint16_t *) cpkt)[i]);

        if (wait_status(ctrl, 0, ~SR_BSY, &status, TIMEOUT_BSY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        if ((status & SR_DRQ) == 0) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        /* Read byte count. */
        data_size = (uint16_t) pio_read_8(&ctrl->cmd->cylinder_low) +
            ((uint16_t) pio_read_8(&ctrl->cmd->cylinder_high) << 8);

        /* Check whether data fits into output buffer. */
        if (data_size > obuf_size) {
                /* Output buffer is too small to store data. */
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        /* Read data from the device buffer. */
        for (i = 0; i < (data_size + 1) / 2; i++) {
                val = pio_read_16(&ctrl->cmd->data_port);
                ((uint16_t *) obuf)[i] = val;
        }

        fibril_mutex_unlock(&ctrl->lock);

        if (status & SR_ERR)
                return EIO;

        if (rcvd_size != NULL)
                *rcvd_size = data_size;
        return EOK;
}

/** Issue ATAPI Inquiry.
 *
 * @param disk          Disk
 * @param obuf          Buffer for storing inquiry data read from device
 * @param obuf_size     Size of obuf in bytes
 *
 * @return EOK on success, EIO on error.
 */
static int ata_pcmd_inquiry(disk_t *disk, void *obuf, size_t obuf_size,
    size_t *rcvd_size)
{
        uint8_t cpb[12];
        scsi_cdb_inquiry_t *cp = (scsi_cdb_inquiry_t *)cpb;
        int rc;

        memset(cpb, 0, sizeof(cpb));

        /*
         * For SFF 8020 compliance the inquiry must be padded to 12 bytes
         * and allocation length must fit in one byte.
         */
        cp->op_code = SCSI_CMD_INQUIRY;

        /* Allocation length */
        cp->alloc_len = host2uint16_t_be(min(obuf_size, 0xff));

        rc = ata_cmd_packet(disk, cpb, sizeof(cpb), obuf, obuf_size, rcvd_size);
        if (rc != EOK)
                return rc;

        return EOK;
}

/** Issue ATAPI read capacity(10) command.
 *
 * @param disk          Disk
 * @param nblocks       Place to store number of blocks
 * @param block_size    Place to store block size
 *
 * @return EOK on success, EIO on error.
 */
static int ata_pcmd_read_capacity(disk_t *disk, uint64_t *nblocks,
    size_t *block_size)
{
        scsi_cdb_read_capacity_10_t cdb;
        scsi_read_capacity_10_data_t data;
        size_t rsize;
        int rc;

        memset(&cdb, 0, sizeof(cdb));
        cdb.op_code = SCSI_CMD_READ_CAPACITY_10;

        rc = ata_cmd_packet(disk, &cdb, sizeof(cdb), &data, sizeof(data), &rsize);
        if (rc != EOK)
                return rc;

        if (rsize != sizeof(data))
                return EIO;

        *nblocks = uint32_t_be2host(data.last_lba) + 1;
        *block_size = uint32_t_be2host(data.block_size);

        return EOK;
}

/** Issue ATAPI read(12) command.
 *
 * Output buffer must be large enough to hold the data, otherwise the
 * function will fail.
 *
 * @param disk          Disk
 * @param ba            Starting block address
 * @param cnt           Number of blocks to read
 * @param obuf          Buffer for storing inquiry data read from device
 * @param obuf_size     Size of obuf in bytes
 *
 * @return EOK on success, EIO on error.
 */
static int ata_pcmd_read_12(disk_t *disk, uint64_t ba, size_t cnt,
    void *obuf, size_t obuf_size)
{
        scsi_cdb_read_12_t cp;
        int rc;

        if (ba > UINT32_MAX)
                return EINVAL;

        memset(&cp, 0, sizeof(cp));

        cp.op_code = SCSI_CMD_READ_12;
        cp.lba = host2uint32_t_be(ba);
        cp.xfer_len = host2uint32_t_be(cnt);

        rc = ata_cmd_packet(disk, &cp, sizeof(cp), obuf, obuf_size, NULL);
        if (rc != EOK)
                return rc;

        return EOK;
}

/** Issue ATAPI read TOC command.
 *
 * Read TOC in 'multi-session' format (first and last session number
 * with last session LBA).
 *
 * http://suif.stanford.edu/~csapuntz/specs/INF-8020.PDF page 171
 *
 * Output buffer must be large enough to hold the data, otherwise the
 * function will fail.
 *
 * @param disk          Disk
 * @param session       Starting session
 * @param obuf          Buffer for storing inquiry data read from device
 * @param obuf_size     Size of obuf in bytes
 *
 * @return EOK on success, EIO on error.
 */
static int ata_pcmd_read_toc(disk_t *disk, uint8_t session, void *obuf,
    size_t obuf_size)
{
        uint8_t cpb[12];
        scsi_cdb_read_toc_t *cp = (scsi_cdb_read_toc_t *)cpb;
        int rc;

        memset(cpb, 0, sizeof(cpb));

        cp->op_code = SCSI_CMD_READ_TOC;
        cp->msf = 0;
        cp->format = 0x01; /* 0x01 = multi-session mode */
        cp->track_sess_no = session;
        cp->alloc_len = host2uint16_t_be(obuf_size);
        cp->control = 0x40; /* 0x01 = multi-session mode (shifted to MSB) */

        rc = ata_cmd_packet(disk, cpb, sizeof(cpb), obuf, obuf_size, NULL);
        if (rc != EOK)
                return rc;

        return EOK;
}

/** Read a physical block from the device.
 *
 * @param disk          Disk
 * @param ba            Address the first block.
 * @param cnt           Number of blocks to transfer.
 * @param buf           Buffer for holding the data.
 *
 * @return EOK on success, EIO on error.
 */
static int ata_rcmd_read(disk_t *disk, uint64_t ba, size_t blk_cnt,
    void *buf)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint8_t drv_head;
        block_coord_t bc;
        int rc;

        /* Silence warning. */
        memset(&bc, 0, sizeof(bc));

        /* Compute block coordinates. */
        if (coord_calc(disk, ba, &bc) != EOK)
                return EINVAL;

        /* New value for Drive/Head register */
        drv_head =
            ((disk_dev_idx(disk) != 0) ? DHR_DRV : 0) |
            ((disk->amode != am_chs) ? DHR_LBA : 0) |
            (bc.h & 0x0f);

        fibril_mutex_lock(&ctrl->lock);

        /* Program a Read Sectors operation. */

        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_BSY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        pio_write_8(&ctrl->cmd->drive_head, drv_head);

        if (wait_status(ctrl, SR_DRDY, ~SR_BSY, NULL, TIMEOUT_DRDY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        /* Program block coordinates into the device. */
        coord_sc_program(ctrl, &bc, 1);

        pio_write_8(&ctrl->cmd->command, disk->amode == am_lba48 ?
            CMD_READ_SECTORS_EXT : CMD_READ_SECTORS);

        rc = ata_pio_data_in(disk, buf, blk_cnt * disk->block_size,
            disk->block_size, blk_cnt);

        fibril_mutex_unlock(&ctrl->lock);

        return rc;
}

/** Write a physical block to the device.
 *
 * @param disk          Disk
 * @param ba            Address of the first block.
 * @param cnt           Number of blocks to transfer.
 * @param buf           Buffer holding the data to write.
 *
 * @return EOK on success, EIO on error.
 */
static int ata_rcmd_write(disk_t *disk, uint64_t ba, size_t cnt,
    const void *buf)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint8_t drv_head;
        block_coord_t bc;
        int rc;

        /* Silence warning. */
        memset(&bc, 0, sizeof(bc));

        /* Compute block coordinates. */
        if (coord_calc(disk, ba, &bc) != EOK)
                return EINVAL;

        /* New value for Drive/Head register */
        drv_head =
            ((disk_dev_idx(disk) != 0) ? DHR_DRV : 0) |
            ((disk->amode != am_chs) ? DHR_LBA : 0) |
            (bc.h & 0x0f);

        fibril_mutex_lock(&ctrl->lock);

        /* Program a Write Sectors operation. */

        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_BSY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        pio_write_8(&ctrl->cmd->drive_head, drv_head);

        if (wait_status(ctrl, SR_DRDY, ~SR_BSY, NULL, TIMEOUT_DRDY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        /* Program block coordinates into the device. */
        coord_sc_program(ctrl, &bc, 1);

        pio_write_8(&ctrl->cmd->command, disk->amode == am_lba48 ?
            CMD_WRITE_SECTORS_EXT : CMD_WRITE_SECTORS);

        rc = ata_pio_data_out(disk, buf, cnt * disk->block_size,
            disk->block_size, cnt);

        fibril_mutex_unlock(&ctrl->lock);
        return rc;
}

/** Flush cached data to nonvolatile storage.
 *
 * @param disk          Disk
 *
 * @return EOK on success, EIO on error.
 */
static int ata_rcmd_flush_cache(disk_t *disk)
{
        ata_ctrl_t *ctrl = disk->ctrl;
        uint8_t drv_head;
        int rc;

        /* New value for Drive/Head register */
        drv_head =
            (disk_dev_idx(disk) != 0) ? DHR_DRV : 0;

        fibril_mutex_lock(&ctrl->lock);

        /* Program a Flush Cache operation. */

        if (wait_status(ctrl, 0, ~SR_BSY, NULL, TIMEOUT_BSY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        pio_write_8(&ctrl->cmd->drive_head, drv_head);

        if (wait_status(ctrl, SR_DRDY, ~SR_BSY, NULL, TIMEOUT_DRDY) != EOK) {
                fibril_mutex_unlock(&ctrl->lock);
                return EIO;
        }

        pio_write_8(&ctrl->cmd->command, CMD_FLUSH_CACHE);

        rc = ata_pio_nondata(disk);

        fibril_mutex_unlock(&ctrl->lock);
        return rc;
}

/** Calculate block coordinates.
 *
 * Calculates block coordinates in the best coordinate system supported
 * by the device. These can be later programmed into the device using
 * @c coord_sc_program().
 *
 * @return EOK on success or EINVAL if block index is past end of device.
 */
static int coord_calc(disk_t *d, uint64_t ba, block_coord_t *bc)
{
        uint64_t c;
        uint64_t idx;

        /* Check device bounds. */
        if (ba >= d->blocks)
                return EINVAL;

        bc->amode = d->amode;

        switch (d->amode) {
        case am_chs:
                /* Compute CHS coordinates. */
                c = ba / (d->geom.heads * d->geom.sectors);
                idx = ba % (d->geom.heads * d->geom.sectors);

                bc->cyl_lo = c & 0xff;
                bc->cyl_hi = (c >> 8) & 0xff;
                bc->h      = (idx / d->geom.sectors) & 0x0f;
                bc->sector = (1 + (idx % d->geom.sectors)) & 0xff;
                break;

        case am_lba28:
                /* Compute LBA-28 coordinates. */
                bc->c0 = ba & 0xff;             /* bits 0-7 */
                bc->c1 = (ba >> 8) & 0xff;      /* bits 8-15 */
                bc->c2 = (ba >> 16) & 0xff;     /* bits 16-23 */
                bc->h  = (ba >> 24) & 0x0f;     /* bits 24-27 */
                break;

        case am_lba48:
                /* Compute LBA-48 coordinates. */
                bc->c0 = ba & 0xff;             /* bits 0-7 */
                bc->c1 = (ba >> 8) & 0xff;      /* bits 8-15 */
                bc->c2 = (ba >> 16) & 0xff;     /* bits 16-23 */
                bc->c3 = (ba >> 24) & 0xff;     /* bits 24-31 */
                bc->c4 = (ba >> 32) & 0xff;     /* bits 32-39 */
                bc->c5 = (ba >> 40) & 0xff;     /* bits 40-47 */
                bc->h  = 0;
                break;
        }

        return EOK;
}

/** Program block coordinates and sector count into ATA registers.
 *
 * Note that bc->h must be programmed separately into the device/head register.
 *
 * @param ctrl          Controller
 * @param bc            Block coordinates
 * @param scnt          Sector count
 */
static void coord_sc_program(ata_ctrl_t *ctrl, const block_coord_t *bc,
    uint16_t scnt)
{
        ata_cmd_t *cmd = ctrl->cmd;

        if (bc->amode == am_lba48) {
                /* Write high-order bits. */
                pio_write_8(&cmd->sector_count, scnt >> 8);
                pio_write_8(&cmd->sector_number, bc->c3);
                pio_write_8(&cmd->cylinder_low, bc->c4);
                pio_write_8(&cmd->cylinder_high, bc->c5);
        }

        /* Write low-order bits. */
        pio_write_8(&cmd->sector_count, scnt & 0x00ff);
        pio_write_8(&cmd->sector_number, bc->c0);
        pio_write_8(&cmd->cylinder_low, bc->c1);
        pio_write_8(&cmd->cylinder_high, bc->c2);
}

/** Wait until some status bits are set and some are reset.
 *
 * Example: wait_status(ctrl, SR_DRDY, ~SR_BSY, ...) waits for SR_DRDY to become
 * set and SR_BSY to become reset.
 *
 * @param ctrl          Controller
 * @param set           Combination if bits which must be all set.
 * @param n_reset       Negated combination of bits which must be all reset.
 * @param pstatus       Pointer where to store last read status or NULL.
 * @param timeout       Timeout in 10ms units.
 *
 * @return              EOK on success, EIO on timeout.
 */
static int wait_status(ata_ctrl_t *ctrl, unsigned set, unsigned n_reset,
    uint8_t *pstatus, unsigned timeout)
{
        uint8_t status;
        int cnt;

        status = pio_read_8(&ctrl->cmd->status);

        /*
         * This is crude, yet simple. First try with 1us delays
         * (most likely the device will respond very fast). If not,
         * start trying every 10 ms.
         */

        cnt = 100;
        while ((status & ~n_reset) != 0 || (status & set) != set) {
                --cnt;
                if (cnt <= 0) break;

                status = pio_read_8(&ctrl->cmd->status);
        }

        cnt = timeout;
        while ((status & ~n_reset) != 0 || (status & set) != set) {
                async_usleep(10000);
                --cnt;
                if (cnt <= 0) break;

                status = pio_read_8(&ctrl->cmd->status);
        }

        if (pstatus)
                *pstatus = status;

        if (cnt == 0)
                return EIO;

        return EOK;
}

/**
 * @}
 */