// SPDX-License-Identifier: GPL-2.0-or-later
/* GD ROM driver for the SEGA Dreamcast
 * copyright Adrian McMenamin, 2007
 * With thanks to Marcus Comstedt and Nathan Keynes
 * for work in reversing PIO and DMA
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <linux/cdrom.h>
#include <linux/bio.h>
#include <linux/blk-mq.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/wait.h>
#include <linux/platform_device.h>
#include <scsi/scsi.h>
#include <asm/io.h>
#include <asm/dma.h>
#include <asm/delay.h>
#include <mach/dma.h>
#include <mach/sysasic.h>

#define GDROM_DEV_NAME "gdrom"
#define GD_SESSION_OFFSET 150

/* GD Rom commands */
#define GDROM_COM_SOFTRESET 0x08
#define GDROM_COM_EXECDIAG 0x90
#define GDROM_COM_PACKET 0xA0
#define GDROM_COM_IDDEV 0xA1

/* GD Rom registers */
#define GDROM_BASE_REG                  0xA05F7000
#define GDROM_ALTSTATUS_REG             (GDROM_BASE_REG + 0x18)
#define GDROM_DATA_REG                  (GDROM_BASE_REG + 0x80)
#define GDROM_ERROR_REG         (GDROM_BASE_REG + 0x84)
#define GDROM_INTSEC_REG                (GDROM_BASE_REG + 0x88)
#define GDROM_SECNUM_REG                (GDROM_BASE_REG + 0x8C)
#define GDROM_BCL_REG                   (GDROM_BASE_REG + 0x90)
#define GDROM_BCH_REG                   (GDROM_BASE_REG + 0x94)
#define GDROM_DSEL_REG                  (GDROM_BASE_REG + 0x98)
#define GDROM_STATUSCOMMAND_REG (GDROM_BASE_REG + 0x9C)
#define GDROM_RESET_REG         (GDROM_BASE_REG + 0x4E4)

#define GDROM_DMA_STARTADDR_REG (GDROM_BASE_REG + 0x404)
#define GDROM_DMA_LENGTH_REG            (GDROM_BASE_REG + 0x408)
#define GDROM_DMA_DIRECTION_REG (GDROM_BASE_REG + 0x40C)
#define GDROM_DMA_ENABLE_REG            (GDROM_BASE_REG + 0x414)
#define GDROM_DMA_STATUS_REG            (GDROM_BASE_REG + 0x418)
#define GDROM_DMA_WAIT_REG              (GDROM_BASE_REG + 0x4A0)
#define GDROM_DMA_ACCESS_CTRL_REG       (GDROM_BASE_REG + 0x4B8)

#define GDROM_HARD_SECTOR       2048
#define BLOCK_LAYER_SECTOR      512
#define GD_TO_BLK               4

#define GDROM_DEFAULT_TIMEOUT   (HZ * 7)

static DEFINE_MUTEX(gdrom_mutex);
static const struct {
        int sense_key;
        const char * const text;
} sense_texts[] = {
        {NO_SENSE, "OK"},
        {RECOVERED_ERROR, "Recovered from error"},
        {NOT_READY, "Device not ready"},
        {MEDIUM_ERROR, "Disk not ready"},
        {HARDWARE_ERROR, "Hardware error"},
        {ILLEGAL_REQUEST, "Command has failed"},
        {UNIT_ATTENTION, "Device needs attention - disk may have been changed"},
        {DATA_PROTECT, "Data protection error"},
        {ABORTED_COMMAND, "Command aborted"},
};

static struct platform_device *pd;
static int gdrom_major;
static DECLARE_WAIT_QUEUE_HEAD(command_queue);
static DECLARE_WAIT_QUEUE_HEAD(request_queue);

struct gdromtoc {
        unsigned int entry[99];
        unsigned int first, last;
        unsigned int leadout;
};

static struct gdrom_unit {
        struct gendisk *disk;
        struct cdrom_device_info *cd_info;
        int status;
        int pending;
        int transfer;
        char disk_type;
        struct gdromtoc *toc;
        struct request_queue *gdrom_rq;
        struct blk_mq_tag_set tag_set;
} gd;

struct gdrom_id {
        char mid;
        char modid;
        char verid;
        char padA[13];
        char mname[16];
        char modname[16];
        char firmver[16];
        char padB[16];
};

static int gdrom_getsense(short *bufstring);
static int gdrom_packetcommand(struct cdrom_device_info *cd_info,
        struct packet_command *command);
static int gdrom_hardreset(struct cdrom_device_info *cd_info);

static bool gdrom_is_busy(void)
{
        return (__raw_readb(GDROM_ALTSTATUS_REG) & 0x80) != 0;
}

static bool gdrom_data_request(void)
{
        return (__raw_readb(GDROM_ALTSTATUS_REG) & 0x88) == 8;
}

static bool gdrom_wait_clrbusy(void)
{
        unsigned long timeout = jiffies + GDROM_DEFAULT_TIMEOUT;
        while ((__raw_readb(GDROM_ALTSTATUS_REG) & 0x80) &&
                (time_before(jiffies, timeout)))
                cpu_relax();
        return time_before(jiffies, timeout + 1);
}

static bool gdrom_wait_busy_sleeps(void)
{
        unsigned long timeout;
        /* Wait to get busy first */
        timeout = jiffies + GDROM_DEFAULT_TIMEOUT;
        while (!gdrom_is_busy() && time_before(jiffies, timeout))
                cpu_relax();
        /* Now wait for busy to clear */
        return gdrom_wait_clrbusy();
}

static void gdrom_identifydevice(void *buf)
{
        int c;
        short *data = buf;
        /* If the device won't clear it has probably
        * been hit by a serious failure - but we'll
        * try to return a sense key even so */
        if (!gdrom_wait_clrbusy()) {
                gdrom_getsense(NULL);
                return;
        }
        __raw_writeb(GDROM_COM_IDDEV, GDROM_STATUSCOMMAND_REG);
        if (!gdrom_wait_busy_sleeps()) {
                gdrom_getsense(NULL);
                return;
        }
        /* now read in the data */
        for (c = 0; c < 40; c++)
                data[c] = __raw_readw(GDROM_DATA_REG);
}

static void gdrom_spicommand(void *spi_string, int buflen)
{
        short *cmd = spi_string;
        unsigned long timeout;

        /* ensure IRQ_WAIT is set */
        __raw_writeb(0x08, GDROM_ALTSTATUS_REG);
        /* specify how many bytes we expect back */
        __raw_writeb(buflen & 0xFF, GDROM_BCL_REG);
        __raw_writeb((buflen >> 8) & 0xFF, GDROM_BCH_REG);
        /* other parameters */
        __raw_writeb(0, GDROM_INTSEC_REG);
        __raw_writeb(0, GDROM_SECNUM_REG);
        __raw_writeb(0, GDROM_ERROR_REG);
        /* Wait until we can go */
        if (!gdrom_wait_clrbusy()) {
                gdrom_getsense(NULL);
                return;
        }
        timeout = jiffies + GDROM_DEFAULT_TIMEOUT;
        __raw_writeb(GDROM_COM_PACKET, GDROM_STATUSCOMMAND_REG);
        while (!gdrom_data_request() && time_before(jiffies, timeout))
                cpu_relax();
        if (!time_before(jiffies, timeout + 1)) {
                gdrom_getsense(NULL);
                return;
        }
        outsw(GDROM_DATA_REG, cmd, 6);
}


/* gdrom_command_executediagnostic:
 * Used to probe for presence of working GDROM
 * Restarts GDROM device and then applies standard ATA 3
 * Execute Diagnostic Command: a return of '1' indicates device 0
 * present and device 1 absent
 */
static char gdrom_execute_diagnostic(void)
{
        gdrom_hardreset(gd.cd_info);
        if (!gdrom_wait_clrbusy())
                return 0;
        __raw_writeb(GDROM_COM_EXECDIAG, GDROM_STATUSCOMMAND_REG);
        if (!gdrom_wait_busy_sleeps())
                return 0;
        return __raw_readb(GDROM_ERROR_REG);
}

/*
 * Prepare disk command
 * byte 0 = 0x70
 * byte 1 = 0x1f
 */
static int gdrom_preparedisk_cmd(void)
{
        struct packet_command *spin_command;
        spin_command = kzalloc_obj(struct packet_command);
        if (!spin_command)
                return -ENOMEM;
        spin_command->cmd[0] = 0x70;
        spin_command->cmd[2] = 0x1f;
        spin_command->buflen = 0;
        gd.pending = 1;
        gdrom_packetcommand(gd.cd_info, spin_command);
        /* 60 second timeout */
        wait_event_interruptible_timeout(command_queue, gd.pending == 0,
                GDROM_DEFAULT_TIMEOUT);
        gd.pending = 0;
        kfree(spin_command);
        if (gd.status & 0x01) {
                /* log an error */
                gdrom_getsense(NULL);
                return -EIO;
        }
        return 0;
}

/*
 * Read TOC command
 * byte 0 = 0x14
 * byte 1 = session
 * byte 3 = sizeof TOC >> 8  ie upper byte
 * byte 4 = sizeof TOC & 0xff ie lower byte
 */
static int gdrom_readtoc_cmd(struct gdromtoc *toc, int session)
{
        int tocsize;
        struct packet_command *toc_command;
        int err = 0;

        toc_command = kzalloc_obj(struct packet_command);
        if (!toc_command)
                return -ENOMEM;
        tocsize = sizeof(struct gdromtoc);
        toc_command->cmd[0] = 0x14;
        toc_command->cmd[1] = session;
        toc_command->cmd[3] = tocsize >> 8;
        toc_command->cmd[4] = tocsize & 0xff;
        toc_command->buflen = tocsize;
        if (gd.pending) {
                err = -EBUSY;
                goto cleanup_readtoc_final;
        }
        gd.pending = 1;
        gdrom_packetcommand(gd.cd_info, toc_command);
        wait_event_interruptible_timeout(command_queue, gd.pending == 0,
                GDROM_DEFAULT_TIMEOUT);
        if (gd.pending) {
                err = -EINVAL;
                goto cleanup_readtoc;
        }
        insw(GDROM_DATA_REG, toc, tocsize/2);
        if (gd.status & 0x01)
                err = -EINVAL;

cleanup_readtoc:
        gd.pending = 0;
cleanup_readtoc_final:
        kfree(toc_command);
        return err;
}

/* TOC helpers */
static int get_entry_lba(int track)
{
        return (cpu_to_be32(track & 0xffffff00) - GD_SESSION_OFFSET);
}

static int get_entry_q_ctrl(int track)
{
        return (track & 0x000000f0) >> 4;
}

static int get_entry_track(int track)
{
        return (track & 0x0000ff00) >> 8;
}

static int gdrom_get_last_session(struct cdrom_device_info *cd_info,
        struct cdrom_multisession *ms_info)
{
        int fentry, lentry, track, data, err;

        if (!gd.toc)
                return -ENOMEM;

        /* Check if GD-ROM */
        err = gdrom_readtoc_cmd(gd.toc, 1);
        /* Not a GD-ROM so check if standard CD-ROM */
        if (err) {
                err = gdrom_readtoc_cmd(gd.toc, 0);
                if (err) {
                        pr_info("Could not get CD table of contents\n");
                        return -ENXIO;
                }
        }

        fentry = get_entry_track(gd.toc->first);
        lentry = get_entry_track(gd.toc->last);
        /* Find the first data track */
        track = get_entry_track(gd.toc->last);
        do {
                data = gd.toc->entry[track - 1];
                if (get_entry_q_ctrl(data))
                        break;  /* ie a real data track */
                track--;
        } while (track >= fentry);

        if ((track > 100) || (track < get_entry_track(gd.toc->first))) {
                pr_info("No data on the last session of the CD\n");
                gdrom_getsense(NULL);
                return -ENXIO;
        }

        ms_info->addr_format = CDROM_LBA;
        ms_info->addr.lba = get_entry_lba(data);
        ms_info->xa_flag = 1;
        return 0;
}

static int gdrom_open(struct cdrom_device_info *cd_info, int purpose)
{
        /* spin up the disk */
        return gdrom_preparedisk_cmd();
}

/* this function is required even if empty */
static void gdrom_release(struct cdrom_device_info *cd_info)
{
}

static int gdrom_drivestatus(struct cdrom_device_info *cd_info, int ignore)
{
        /* read the sense key */
        char sense = __raw_readb(GDROM_ERROR_REG);
        sense &= 0xF0;
        if (sense == 0)
                return CDS_DISC_OK;
        if (sense == 0x20)
                return CDS_DRIVE_NOT_READY;
        /* default */
        return CDS_NO_INFO;
}

static unsigned int gdrom_check_events(struct cdrom_device_info *cd_info,
                                       unsigned int clearing, int ignore)
{
        /* check the sense key */
        return (__raw_readb(GDROM_ERROR_REG) & 0xF0) == 0x60 ?
                DISK_EVENT_MEDIA_CHANGE : 0;
}

/* reset the G1 bus */
static int gdrom_hardreset(struct cdrom_device_info *cd_info)
{
        int count;
        __raw_writel(0x1fffff, GDROM_RESET_REG);
        for (count = 0xa0000000; count < 0xa0200000; count += 4)
                __raw_readl(count);
        return 0;
}

/* keep the function looking like the universal
 * CD Rom specification  - returning int */
static int gdrom_packetcommand(struct cdrom_device_info *cd_info,
        struct packet_command *command)
{
        gdrom_spicommand(&command->cmd, command->buflen);
        return 0;
}

/* Get Sense SPI command
 * From Marcus Comstedt
 * cmd = 0x13
 * cmd + 4 = length of returned buffer
 * Returns 5 16 bit words
 */
static int gdrom_getsense(short *bufstring)
{
        struct packet_command *sense_command;
        short sense[5];
        int sense_key;
        int err = -EIO;

        sense_command = kzalloc_obj(struct packet_command);
        if (!sense_command)
                return -ENOMEM;
        sense_command->cmd[0] = 0x13;
        sense_command->cmd[4] = 10;
        sense_command->buflen = 10;
        /* even if something is pending try to get
        * the sense key if possible */
        if (gd.pending && !gdrom_wait_clrbusy()) {
                err = -EBUSY;
                goto cleanup_sense_final;
        }
        gd.pending = 1;
        gdrom_packetcommand(gd.cd_info, sense_command);
        wait_event_interruptible_timeout(command_queue, gd.pending == 0,
                GDROM_DEFAULT_TIMEOUT);
        if (gd.pending)
                goto cleanup_sense;
        insw(GDROM_DATA_REG, &sense, sense_command->buflen/2);
        if (sense[1] & 40) {
                pr_info("Drive not ready - command aborted\n");
                goto cleanup_sense;
        }
        sense_key = sense[1] & 0x0F;
        if (sense_key < ARRAY_SIZE(sense_texts))
                pr_info("%s\n", sense_texts[sense_key].text);
        else
                pr_err("Unknown sense key: %d\n", sense_key);
        if (bufstring) /* return addional sense data */
                memcpy(bufstring, &sense[4], 2);
        if (sense_key < 2)
                err = 0;

cleanup_sense:
        gd.pending = 0;
cleanup_sense_final:
        kfree(sense_command);
        return err;
}

static int gdrom_audio_ioctl(struct cdrom_device_info *cdi, unsigned int cmd,
                             void *arg)
{
        return -EINVAL;
}

static const struct cdrom_device_ops gdrom_ops = {
        .open                   = gdrom_open,
        .release                = gdrom_release,
        .drive_status           = gdrom_drivestatus,
        .check_events           = gdrom_check_events,
        .get_last_session       = gdrom_get_last_session,
        .reset                  = gdrom_hardreset,
        .audio_ioctl            = gdrom_audio_ioctl,
        .generic_packet         = cdrom_dummy_generic_packet,
        .capability             = CDC_MULTI_SESSION | CDC_MEDIA_CHANGED |
                                  CDC_RESET | CDC_DRIVE_STATUS | CDC_CD_R,
};

static int gdrom_bdops_open(struct gendisk *disk, blk_mode_t mode)
{
        int ret;

        disk_check_media_change(disk);

        mutex_lock(&gdrom_mutex);
        ret = cdrom_open(gd.cd_info, mode);
        mutex_unlock(&gdrom_mutex);
        return ret;
}

static void gdrom_bdops_release(struct gendisk *disk)
{
        mutex_lock(&gdrom_mutex);
        cdrom_release(gd.cd_info);
        mutex_unlock(&gdrom_mutex);
}

static unsigned int gdrom_bdops_check_events(struct gendisk *disk,
                                             unsigned int clearing)
{
        return cdrom_check_events(gd.cd_info, clearing);
}

static int gdrom_bdops_ioctl(struct block_device *bdev, blk_mode_t mode,
        unsigned cmd, unsigned long arg)
{
        int ret;

        mutex_lock(&gdrom_mutex);
        ret = cdrom_ioctl(gd.cd_info, bdev, cmd, arg);
        mutex_unlock(&gdrom_mutex);

        return ret;
}

static const struct block_device_operations gdrom_bdops = {
        .owner                  = THIS_MODULE,
        .open                   = gdrom_bdops_open,
        .release                = gdrom_bdops_release,
        .check_events           = gdrom_bdops_check_events,
        .ioctl                  = gdrom_bdops_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl           = blkdev_compat_ptr_ioctl,
#endif
};

static irqreturn_t gdrom_command_interrupt(int irq, void *dev_id)
{
        gd.status = __raw_readb(GDROM_STATUSCOMMAND_REG);
        if (gd.pending != 1)
                return IRQ_HANDLED;
        gd.pending = 0;
        wake_up_interruptible(&command_queue);
        return IRQ_HANDLED;
}

static irqreturn_t gdrom_dma_interrupt(int irq, void *dev_id)
{
        gd.status = __raw_readb(GDROM_STATUSCOMMAND_REG);
        if (gd.transfer != 1)
                return IRQ_HANDLED;
        gd.transfer = 0;
        wake_up_interruptible(&request_queue);
        return IRQ_HANDLED;
}

static int gdrom_set_interrupt_handlers(void)
{
        int err;

        err = request_irq(HW_EVENT_GDROM_CMD, gdrom_command_interrupt,
                0, "gdrom_command", &gd);
        if (err)
                return err;
        err = request_irq(HW_EVENT_GDROM_DMA, gdrom_dma_interrupt,
                0, "gdrom_dma", &gd);
        if (err)
                free_irq(HW_EVENT_GDROM_CMD, &gd);
        return err;
}

/* Implement DMA read using SPI command
 * 0 -> 0x30
 * 1 -> mode
 * 2 -> block >> 16
 * 3 -> block >> 8
 * 4 -> block
 * 8 -> sectors >> 16
 * 9 -> sectors >> 8
 * 10 -> sectors
 */
static blk_status_t gdrom_readdisk_dma(struct request *req)
{
        int block, block_cnt;
        blk_status_t err;
        struct packet_command *read_command;
        unsigned long timeout;

        read_command = kzalloc_obj(struct packet_command);
        if (!read_command)
                return BLK_STS_RESOURCE;

        read_command->cmd[0] = 0x30;
        read_command->cmd[1] = 0x20;
        block = blk_rq_pos(req)/GD_TO_BLK + GD_SESSION_OFFSET;
        block_cnt = blk_rq_sectors(req)/GD_TO_BLK;
        __raw_writel(page_to_phys(bio_page(req->bio)) + bio_offset(req->bio),
                        GDROM_DMA_STARTADDR_REG);
        __raw_writel(block_cnt * GDROM_HARD_SECTOR, GDROM_DMA_LENGTH_REG);
        __raw_writel(1, GDROM_DMA_DIRECTION_REG);
        __raw_writel(1, GDROM_DMA_ENABLE_REG);
        read_command->cmd[2] = (block >> 16) & 0xFF;
        read_command->cmd[3] = (block >> 8) & 0xFF;
        read_command->cmd[4] = block & 0xFF;
        read_command->cmd[8] = (block_cnt >> 16) & 0xFF;
        read_command->cmd[9] = (block_cnt >> 8) & 0xFF;
        read_command->cmd[10] = block_cnt & 0xFF;
        /* set for DMA */
        __raw_writeb(1, GDROM_ERROR_REG);
        /* other registers */
        __raw_writeb(0, GDROM_SECNUM_REG);
        __raw_writeb(0, GDROM_BCL_REG);
        __raw_writeb(0, GDROM_BCH_REG);
        __raw_writeb(0, GDROM_DSEL_REG);
        __raw_writeb(0, GDROM_INTSEC_REG);
        /* Wait for registers to reset after any previous activity */
        timeout = jiffies + HZ / 2;
        while (gdrom_is_busy() && time_before(jiffies, timeout))
                cpu_relax();
        __raw_writeb(GDROM_COM_PACKET, GDROM_STATUSCOMMAND_REG);
        timeout = jiffies + HZ / 2;
        /* Wait for packet command to finish */
        while (gdrom_is_busy() && time_before(jiffies, timeout))
                cpu_relax();
        gd.pending = 1;
        gd.transfer = 1;
        outsw(GDROM_DATA_REG, &read_command->cmd, 6);
        timeout = jiffies + HZ / 2;
        /* Wait for any pending DMA to finish */
        while (__raw_readb(GDROM_DMA_STATUS_REG) &&
                time_before(jiffies, timeout))
                cpu_relax();
        /* start transfer */
        __raw_writeb(1, GDROM_DMA_STATUS_REG);
        wait_event_interruptible_timeout(request_queue,
                gd.transfer == 0, GDROM_DEFAULT_TIMEOUT);
        err = gd.transfer ? BLK_STS_IOERR : BLK_STS_OK;
        gd.transfer = 0;
        gd.pending = 0;

        blk_mq_end_request(req, err);
        kfree(read_command);
        return BLK_STS_OK;
}

static blk_status_t gdrom_queue_rq(struct blk_mq_hw_ctx *hctx,
                                   const struct blk_mq_queue_data *bd)
{
        blk_mq_start_request(bd->rq);

        switch (req_op(bd->rq)) {
        case REQ_OP_READ:
                return gdrom_readdisk_dma(bd->rq);
        case REQ_OP_WRITE:
                pr_notice("Read only device - write request ignored\n");
                return BLK_STS_IOERR;
        default:
                printk(KERN_DEBUG "gdrom: Non-fs request ignored\n");
                return BLK_STS_IOERR;
        }
}

/* Print string identifying GD ROM device */
static int gdrom_outputversion(void)
{
        struct gdrom_id *id;
        char *model_name, *manuf_name, *firmw_ver;
        int err = -ENOMEM;

        /* query device ID */
        id = kzalloc_obj(struct gdrom_id);
        if (!id)
                return err;
        gdrom_identifydevice(id);
        model_name = kstrndup(id->modname, 16, GFP_KERNEL);
        if (!model_name)
                goto free_id;
        manuf_name = kstrndup(id->mname, 16, GFP_KERNEL);
        if (!manuf_name)
                goto free_model_name;
        firmw_ver = kstrndup(id->firmver, 16, GFP_KERNEL);
        if (!firmw_ver)
                goto free_manuf_name;
        pr_info("%s from %s with firmware %s\n",
                model_name, manuf_name, firmw_ver);
        err = 0;
        kfree(firmw_ver);
free_manuf_name:
        kfree(manuf_name);
free_model_name:
        kfree(model_name);
free_id:
        kfree(id);
        return err;
}

/* set the default mode for DMA transfer */
static int gdrom_init_dma_mode(void)
{
        __raw_writeb(0x13, GDROM_ERROR_REG);
        __raw_writeb(0x22, GDROM_INTSEC_REG);
        if (!gdrom_wait_clrbusy())
                return -EBUSY;
        __raw_writeb(0xEF, GDROM_STATUSCOMMAND_REG);
        if (!gdrom_wait_busy_sleeps())
                return -EBUSY;
        /* Memory protection setting for GDROM DMA
        * Bits 31 - 16 security: 0x8843
        * Bits 15 and 7 reserved (0)
        * Bits 14 - 8 start of transfer range in 1 MB blocks OR'ed with 0x80
        * Bits 6 - 0 end of transfer range in 1 MB blocks OR'ed with 0x80
        * (0x40 | 0x80) = start range at 0x0C000000
        * (0x7F | 0x80) = end range at 0x0FFFFFFF */
        __raw_writel(0x8843407F, GDROM_DMA_ACCESS_CTRL_REG);
        __raw_writel(9, GDROM_DMA_WAIT_REG); /* DMA word setting */
        return 0;
}

static void probe_gdrom_setupcd(void)
{
        gd.cd_info->ops = &gdrom_ops;
        gd.cd_info->capacity = 1;
        strcpy(gd.cd_info->name, GDROM_DEV_NAME);
        gd.cd_info->mask = CDC_CLOSE_TRAY|CDC_OPEN_TRAY|CDC_LOCK|
                CDC_SELECT_DISC;
}

static void probe_gdrom_setupdisk(void)
{
        gd.disk->major = gdrom_major;
        gd.disk->first_minor = 1;
        gd.disk->minors = 1;
        gd.disk->flags |= GENHD_FL_NO_PART;
        strcpy(gd.disk->disk_name, GDROM_DEV_NAME);
}

static int probe_gdrom_setupqueue(void)
{
        gd.disk->queue = gd.gdrom_rq;
        return gdrom_init_dma_mode();
}

static const struct blk_mq_ops gdrom_mq_ops = {
        .queue_rq       = gdrom_queue_rq,
};

/*
 * register this as a block device and as compliant with the
 * universal CD Rom driver interface
 */
static int probe_gdrom(struct platform_device *devptr)
{
        struct queue_limits lim = {
                .logical_block_size             = GDROM_HARD_SECTOR,
                /* using DMA so memory will need to be contiguous */
                .max_segments                   = 1,
                /* set a large max size to get most from DMA */
                .max_segment_size               = 0x40000,
                .features                       = BLK_FEAT_ROTATIONAL,
        };
        int err;

        /*
         * Ensure our "one" device is initialized properly in case of previous
         * usages of it
         */
        memset(&gd, 0, sizeof(gd));

        /* Start the device */
        if (gdrom_execute_diagnostic() != 1) {
                pr_warn("ATA Probe for GDROM failed\n");
                return -ENODEV;
        }
        /* Print out firmware ID */
        if (gdrom_outputversion())
                return -ENOMEM;
        /* Register GDROM */
        gdrom_major = register_blkdev(0, GDROM_DEV_NAME);
        if (gdrom_major <= 0)
                return gdrom_major;
        pr_info("Registered with major number %d\n",
                gdrom_major);
        /* Specify basic properties of drive */
        gd.cd_info = kzalloc_obj(struct cdrom_device_info);
        if (!gd.cd_info) {
                err = -ENOMEM;
                goto probe_fail_no_mem;
        }
        probe_gdrom_setupcd();

        err = blk_mq_alloc_sq_tag_set(&gd.tag_set, &gdrom_mq_ops, 1,
                                BLK_MQ_F_BLOCKING);
        if (err)
                goto probe_fail_free_cd_info;

        gd.disk = blk_mq_alloc_disk(&gd.tag_set, &lim, NULL);
        if (IS_ERR(gd.disk)) {
                err = PTR_ERR(gd.disk);
                goto probe_fail_free_tag_set;
        }
        gd.gdrom_rq = gd.disk->queue;
        probe_gdrom_setupdisk();
        if (register_cdrom(gd.disk, gd.cd_info)) {
                err = -ENODEV;
                goto probe_fail_cleanup_disk;
        }
        gd.disk->fops = &gdrom_bdops;
        gd.disk->events = DISK_EVENT_MEDIA_CHANGE;
        /* latch on to the interrupt */
        err = gdrom_set_interrupt_handlers();
        if (err)
                goto probe_fail_cleanup_disk;

        err = probe_gdrom_setupqueue();
        if (err)
                goto probe_fail_free_irqs;

        gd.toc = kzalloc_obj(struct gdromtoc);
        if (!gd.toc) {
                err = -ENOMEM;
                goto probe_fail_free_irqs;
        }
        err = add_disk(gd.disk);
        if (err)
                goto probe_fail_add_disk;

        return 0;

probe_fail_add_disk:
        kfree(gd.toc);
probe_fail_free_irqs:
        free_irq(HW_EVENT_GDROM_DMA, &gd);
        free_irq(HW_EVENT_GDROM_CMD, &gd);
probe_fail_cleanup_disk:
        put_disk(gd.disk);
probe_fail_free_tag_set:
        blk_mq_free_tag_set(&gd.tag_set);
probe_fail_free_cd_info:
        kfree(gd.cd_info);
probe_fail_no_mem:
        unregister_blkdev(gdrom_major, GDROM_DEV_NAME);
        gdrom_major = 0;
        pr_warn("Probe failed - error is 0x%X\n", err);
        return err;
}

static void remove_gdrom(struct platform_device *devptr)
{
        blk_mq_free_tag_set(&gd.tag_set);
        free_irq(HW_EVENT_GDROM_CMD, &gd);
        free_irq(HW_EVENT_GDROM_DMA, &gd);
        del_gendisk(gd.disk);
        if (gdrom_major)
                unregister_blkdev(gdrom_major, GDROM_DEV_NAME);
        unregister_cdrom(gd.cd_info);
        kfree(gd.cd_info);
        kfree(gd.toc);
}

static struct platform_driver gdrom_driver = {
        .probe = probe_gdrom,
        .remove = remove_gdrom,
        .driver = {
                        .name = GDROM_DEV_NAME,
        },
};

static int __init init_gdrom(void)
{
        int rc;

        rc = platform_driver_register(&gdrom_driver);
        if (rc)
                return rc;
        pd = platform_device_register_simple(GDROM_DEV_NAME, -1, NULL, 0);
        if (IS_ERR(pd)) {
                platform_driver_unregister(&gdrom_driver);
                return PTR_ERR(pd);
        }
        return 0;
}

static void __exit exit_gdrom(void)
{
        platform_device_unregister(pd);
        platform_driver_unregister(&gdrom_driver);
}

module_init(init_gdrom);
module_exit(exit_gdrom);
MODULE_AUTHOR("Adrian McMenamin <adrian@mcmen.demon.co.uk>");
MODULE_DESCRIPTION("SEGA Dreamcast GD-ROM Driver");
MODULE_LICENSE("GPL");