[mirror_ubuntu-hirsute-kernel.git] / drivers / block / sunvdc.c

/* sunvdc.c: Sun LDOM Virtual Disk Client.
 *
 * Copyright (C) 2007, 2008 David S. Miller <davem@davemloft.net>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/blk-mq.h>
#include <linux/hdreg.h>
#include <linux/genhd.h>
#include <linux/cdrom.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/scatterlist.h>

#include <asm/vio.h>
#include <asm/ldc.h>

#define DRV_MODULE_NAME         "sunvdc"
#define PFX DRV_MODULE_NAME     ": "
#define DRV_MODULE_VERSION      "1.2"
#define DRV_MODULE_RELDATE      "November 24, 2014"

static char version[] =
        DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n";
MODULE_AUTHOR("David S. Miller (davem@davemloft.net)");
MODULE_DESCRIPTION("Sun LDOM virtual disk client driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_MODULE_VERSION);

#define VDC_TX_RING_SIZE        512
#define VDC_DEFAULT_BLK_SIZE    512

#define MAX_XFER_BLKS           (128 * 1024)
#define MAX_XFER_SIZE           (MAX_XFER_BLKS / VDC_DEFAULT_BLK_SIZE)
#define MAX_RING_COOKIES        ((MAX_XFER_BLKS / PAGE_SIZE) + 2)

#define WAITING_FOR_LINK_UP     0x01
#define WAITING_FOR_TX_SPACE    0x02
#define WAITING_FOR_GEN_CMD     0x04
#define WAITING_FOR_ANY         -1

#define VDC_MAX_RETRIES 10

static struct workqueue_struct *sunvdc_wq;

struct vdc_req_entry {
        struct request          *req;
};

struct vdc_port {
        struct vio_driver_state vio;

        struct gendisk          *disk;

        struct vdc_completion   *cmp;

        u64                     req_id;
        u64                     seq;
        struct vdc_req_entry    rq_arr[VDC_TX_RING_SIZE];

        unsigned long           ring_cookies;

        u64                     max_xfer_size;
        u32                     vdisk_block_size;
        u32                     drain;

        u64                     ldc_timeout;
        struct delayed_work     ldc_reset_timer_work;
        struct work_struct      ldc_reset_work;

        /* The server fills these in for us in the disk attribute
         * ACK packet.
         */
        u64                     operations;
        u32                     vdisk_size;
        u8                      vdisk_type;
        u8                      vdisk_mtype;
        u32                     vdisk_phys_blksz;

        struct blk_mq_tag_set   tag_set;

        char                    disk_name[32];
};

static void vdc_ldc_reset(struct vdc_port *port);
static void vdc_ldc_reset_work(struct work_struct *work);
static void vdc_ldc_reset_timer_work(struct work_struct *work);

static inline struct vdc_port *to_vdc_port(struct vio_driver_state *vio)
{
        return container_of(vio, struct vdc_port, vio);
}

/* Ordered from largest major to lowest */
static struct vio_version vdc_versions[] = {
        { .major = 1, .minor = 2 },
        { .major = 1, .minor = 1 },
        { .major = 1, .minor = 0 },
};

static inline int vdc_version_supported(struct vdc_port *port,
                                        u16 major, u16 minor)
{
        return port->vio.ver.major == major && port->vio.ver.minor >= minor;
}

#define VDCBLK_NAME     "vdisk"
static int vdc_major;
#define PARTITION_SHIFT 3

static inline u32 vdc_tx_dring_avail(struct vio_dring_state *dr)
{
        return vio_dring_avail(dr, VDC_TX_RING_SIZE);
}

static int vdc_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
        struct gendisk *disk = bdev->bd_disk;
        sector_t nsect = get_capacity(disk);
        sector_t cylinders = nsect;

        geo->heads = 0xff;
        geo->sectors = 0x3f;
        sector_div(cylinders, geo->heads * geo->sectors);
        geo->cylinders = cylinders;
        if ((sector_t)(geo->cylinders + 1) * geo->heads * geo->sectors < nsect)
                geo->cylinders = 0xffff;

        return 0;
}

/* Add ioctl/CDROM_GET_CAPABILITY to support cdrom_id in udev
 * when vdisk_mtype is VD_MEDIA_TYPE_CD or VD_MEDIA_TYPE_DVD.
 * Needed to be able to install inside an ldom from an iso image.
 */
static int vdc_ioctl(struct block_device *bdev, fmode_t mode,
                     unsigned command, unsigned long argument)
{
        int i;
        struct gendisk *disk;

        switch (command) {
        case CDROMMULTISESSION:
                pr_debug(PFX "Multisession CDs not supported\n");
                for (i = 0; i < sizeof(struct cdrom_multisession); i++)
                        if (put_user(0, (char __user *)(argument + i)))
                                return -EFAULT;
                return 0;

        case CDROM_GET_CAPABILITY:
                disk = bdev->bd_disk;

                if (bdev->bd_disk && (disk->flags & GENHD_FL_CD))
                        return 0;
                return -EINVAL;

        default:
                pr_debug(PFX "ioctl %08x not supported\n", command);
                return -EINVAL;
        }
}

static const struct block_device_operations vdc_fops = {
        .owner          = THIS_MODULE,
        .getgeo         = vdc_getgeo,
        .ioctl          = vdc_ioctl,
};

static void vdc_blk_queue_start(struct vdc_port *port)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];

        /* restart blk queue when ring is half emptied. also called after
         * handshake completes, so check for initial handshake before we've
         * allocated a disk.
         */
        if (port->disk && vdc_tx_dring_avail(dr) * 100 / VDC_TX_RING_SIZE >= 50)
                blk_mq_start_hw_queues(port->disk->queue);
}

static void vdc_finish(struct vio_driver_state *vio, int err, int waiting_for)
{
        if (vio->cmp &&
            (waiting_for == -1 ||
             vio->cmp->waiting_for == waiting_for)) {
                vio->cmp->err = err;
                complete(&vio->cmp->com);
                vio->cmp = NULL;
        }
}

static void vdc_handshake_complete(struct vio_driver_state *vio)
{
        struct vdc_port *port = to_vdc_port(vio);

        cancel_delayed_work(&port->ldc_reset_timer_work);
        vdc_finish(vio, 0, WAITING_FOR_LINK_UP);
        vdc_blk_queue_start(port);
}

static int vdc_handle_unknown(struct vdc_port *port, void *arg)
{
        struct vio_msg_tag *pkt = arg;

        printk(KERN_ERR PFX "Received unknown msg [%02x:%02x:%04x:%08x]\n",
               pkt->type, pkt->stype, pkt->stype_env, pkt->sid);
        printk(KERN_ERR PFX "Resetting connection.\n");

        ldc_disconnect(port->vio.lp);

        return -ECONNRESET;
}

static int vdc_send_attr(struct vio_driver_state *vio)
{
        struct vdc_port *port = to_vdc_port(vio);
        struct vio_disk_attr_info pkt;

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

        pkt.tag.type = VIO_TYPE_CTRL;
        pkt.tag.stype = VIO_SUBTYPE_INFO;
        pkt.tag.stype_env = VIO_ATTR_INFO;
        pkt.tag.sid = vio_send_sid(vio);

        pkt.xfer_mode = VIO_DRING_MODE;
        pkt.vdisk_block_size = port->vdisk_block_size;
        pkt.max_xfer_size = port->max_xfer_size;

        viodbg(HS, "SEND ATTR xfer_mode[0x%x] blksz[%u] max_xfer[%llu]\n",
               pkt.xfer_mode, pkt.vdisk_block_size, pkt.max_xfer_size);

        return vio_ldc_send(&port->vio, &pkt, sizeof(pkt));
}

static int vdc_handle_attr(struct vio_driver_state *vio, void *arg)
{
        struct vdc_port *port = to_vdc_port(vio);
        struct vio_disk_attr_info *pkt = arg;

        viodbg(HS, "GOT ATTR stype[0x%x] ops[%llx] disk_size[%llu] disk_type[%x] "
               "mtype[0x%x] xfer_mode[0x%x] blksz[%u] max_xfer[%llu]\n",
               pkt->tag.stype, pkt->operations,
               pkt->vdisk_size, pkt->vdisk_type, pkt->vdisk_mtype,
               pkt->xfer_mode, pkt->vdisk_block_size,
               pkt->max_xfer_size);

        if (pkt->tag.stype == VIO_SUBTYPE_ACK) {
                switch (pkt->vdisk_type) {
                case VD_DISK_TYPE_DISK:
                case VD_DISK_TYPE_SLICE:
                        break;

                default:
                        printk(KERN_ERR PFX "%s: Bogus vdisk_type 0x%x\n",
                               vio->name, pkt->vdisk_type);
                        return -ECONNRESET;
                }

                if (pkt->vdisk_block_size > port->vdisk_block_size) {
                        printk(KERN_ERR PFX "%s: BLOCK size increased "
                               "%u --> %u\n",
                               vio->name,
                               port->vdisk_block_size, pkt->vdisk_block_size);
                        return -ECONNRESET;
                }

                port->operations = pkt->operations;
                port->vdisk_type = pkt->vdisk_type;
                if (vdc_version_supported(port, 1, 1)) {
                        port->vdisk_size = pkt->vdisk_size;
                        port->vdisk_mtype = pkt->vdisk_mtype;
                }
                if (pkt->max_xfer_size < port->max_xfer_size)
                        port->max_xfer_size = pkt->max_xfer_size;
                port->vdisk_block_size = pkt->vdisk_block_size;

                port->vdisk_phys_blksz = VDC_DEFAULT_BLK_SIZE;
                if (vdc_version_supported(port, 1, 2))
                        port->vdisk_phys_blksz = pkt->phys_block_size;

                return 0;
        } else {
                printk(KERN_ERR PFX "%s: Attribute NACK\n", vio->name);

                return -ECONNRESET;
        }
}

static void vdc_end_special(struct vdc_port *port, struct vio_disk_desc *desc)
{
        int err = desc->status;

        vdc_finish(&port->vio, -err, WAITING_FOR_GEN_CMD);
}

static void vdc_end_one(struct vdc_port *port, struct vio_dring_state *dr,
                        unsigned int index)
{
        struct vio_disk_desc *desc = vio_dring_entry(dr, index);
        struct vdc_req_entry *rqe = &port->rq_arr[index];
        struct request *req;

        if (unlikely(desc->hdr.state != VIO_DESC_DONE))
                return;

        ldc_unmap(port->vio.lp, desc->cookies, desc->ncookies);
        desc->hdr.state = VIO_DESC_FREE;
        dr->cons = vio_dring_next(dr, index);

        req = rqe->req;
        if (req == NULL) {
                vdc_end_special(port, desc);
                return;
        }

        rqe->req = NULL;

        blk_mq_end_request(req, desc->status ? BLK_STS_IOERR : 0);

        vdc_blk_queue_start(port);
}

static int vdc_ack(struct vdc_port *port, void *msgbuf)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct vio_dring_data *pkt = msgbuf;

        if (unlikely(pkt->dring_ident != dr->ident ||
                     pkt->start_idx != pkt->end_idx ||
                     pkt->start_idx >= VDC_TX_RING_SIZE))
                return 0;

        vdc_end_one(port, dr, pkt->start_idx);

        return 0;
}

static int vdc_nack(struct vdc_port *port, void *msgbuf)
{
        /* XXX Implement me XXX */
        return 0;
}

static void vdc_event(void *arg, int event)
{
        struct vdc_port *port = arg;
        struct vio_driver_state *vio = &port->vio;
        unsigned long flags;
        int err;

        spin_lock_irqsave(&vio->lock, flags);

        if (unlikely(event == LDC_EVENT_RESET)) {
                vio_link_state_change(vio, event);
                queue_work(sunvdc_wq, &port->ldc_reset_work);
                goto out;
        }

        if (unlikely(event == LDC_EVENT_UP)) {
                vio_link_state_change(vio, event);
                goto out;
        }

        if (unlikely(event != LDC_EVENT_DATA_READY)) {
                pr_warn(PFX "Unexpected LDC event %d\n", event);
                goto out;
        }

        err = 0;
        while (1) {
                union {
                        struct vio_msg_tag tag;
                        u64 raw[8];
                } msgbuf;

                err = ldc_read(vio->lp, &msgbuf, sizeof(msgbuf));
                if (unlikely(err < 0)) {
                        if (err == -ECONNRESET)
                                vio_conn_reset(vio);
                        break;
                }
                if (err == 0)
                        break;
                viodbg(DATA, "TAG [%02x:%02x:%04x:%08x]\n",
                       msgbuf.tag.type,
                       msgbuf.tag.stype,
                       msgbuf.tag.stype_env,
                       msgbuf.tag.sid);
                err = vio_validate_sid(vio, &msgbuf.tag);
                if (err < 0)
                        break;

                if (likely(msgbuf.tag.type == VIO_TYPE_DATA)) {
                        if (msgbuf.tag.stype == VIO_SUBTYPE_ACK)
                                err = vdc_ack(port, &msgbuf);
                        else if (msgbuf.tag.stype == VIO_SUBTYPE_NACK)
                                err = vdc_nack(port, &msgbuf);
                        else
                                err = vdc_handle_unknown(port, &msgbuf);
                } else if (msgbuf.tag.type == VIO_TYPE_CTRL) {
                        err = vio_control_pkt_engine(vio, &msgbuf);
                } else {
                        err = vdc_handle_unknown(port, &msgbuf);
                }
                if (err < 0)
                        break;
        }
        if (err < 0)
                vdc_finish(&port->vio, err, WAITING_FOR_ANY);
out:
        spin_unlock_irqrestore(&vio->lock, flags);
}

static int __vdc_tx_trigger(struct vdc_port *port)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct vio_dring_data hdr = {
                .tag = {
                        .type           = VIO_TYPE_DATA,
                        .stype          = VIO_SUBTYPE_INFO,
                        .stype_env      = VIO_DRING_DATA,
                        .sid            = vio_send_sid(&port->vio),
                },
                .dring_ident            = dr->ident,
                .start_idx              = dr->prod,
                .end_idx                = dr->prod,
        };
        int err, delay;
        int retries = 0;

        hdr.seq = dr->snd_nxt;
        delay = 1;
        do {
                err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
                if (err > 0) {
                        dr->snd_nxt++;
                        break;
                }
                udelay(delay);
                if ((delay <<= 1) > 128)
                        delay = 128;
                if (retries++ > VDC_MAX_RETRIES)
                        break;
        } while (err == -EAGAIN);

        if (err == -ENOTCONN)
                vdc_ldc_reset(port);
        return err;
}

static int __send_request(struct request *req)
{
        struct vdc_port *port = req->rq_disk->private_data;
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        struct scatterlist sg[MAX_RING_COOKIES];
        struct vdc_req_entry *rqe;
        struct vio_disk_desc *desc;
        unsigned int map_perm;
        int nsg, err, i;
        u64 len;
        u8 op;

        if (WARN_ON(port->ring_cookies > MAX_RING_COOKIES))
                return -EINVAL;

        map_perm = LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;

        if (rq_data_dir(req) == READ) {
                map_perm |= LDC_MAP_W;
                op = VD_OP_BREAD;
        } else {
                map_perm |= LDC_MAP_R;
                op = VD_OP_BWRITE;
        }

        sg_init_table(sg, port->ring_cookies);
        nsg = blk_rq_map_sg(req->q, req, sg);

        len = 0;
        for (i = 0; i < nsg; i++)
                len += sg[i].length;

        desc = vio_dring_cur(dr);

        err = ldc_map_sg(port->vio.lp, sg, nsg,
                         desc->cookies, port->ring_cookies,
                         map_perm);
        if (err < 0) {
                printk(KERN_ERR PFX "ldc_map_sg() failure, err=%d.\n", err);
                return err;
        }

        rqe = &port->rq_arr[dr->prod];
        rqe->req = req;

        desc->hdr.ack = VIO_ACK_ENABLE;
        desc->req_id = port->req_id;
        desc->operation = op;
        if (port->vdisk_type == VD_DISK_TYPE_DISK) {
                desc->slice = 0xff;
        } else {
                desc->slice = 0;
        }
        desc->status = ~0;
        desc->offset = (blk_rq_pos(req) << 9) / port->vdisk_block_size;
        desc->size = len;
        desc->ncookies = err;

        /* This has to be a non-SMP write barrier because we are writing
         * to memory which is shared with the peer LDOM.
         */
        wmb();
        desc->hdr.state = VIO_DESC_READY;

        err = __vdc_tx_trigger(port);
        if (err < 0) {
                printk(KERN_ERR PFX "vdc_tx_trigger() failure, err=%d\n", err);
        } else {
                port->req_id++;
                dr->prod = vio_dring_next(dr, dr->prod);
        }

        return err;
}

static blk_status_t vdc_queue_rq(struct blk_mq_hw_ctx *hctx,
                                 const struct blk_mq_queue_data *bd)
{
        struct vdc_port *port = hctx->queue->queuedata;
        struct vio_dring_state *dr;
        unsigned long flags;

        dr = &port->vio.drings[VIO_DRIVER_TX_RING];

        blk_mq_start_request(bd->rq);

        spin_lock_irqsave(&port->vio.lock, flags);

        /*
         * Doing drain, just end the request in error
         */
        if (unlikely(port->drain)) {
                spin_unlock_irqrestore(&port->vio.lock, flags);
                return BLK_STS_IOERR;
        }

        if (unlikely(vdc_tx_dring_avail(dr) < 1)) {
                spin_unlock_irqrestore(&port->vio.lock, flags);
                blk_mq_stop_hw_queue(hctx);
                return BLK_STS_DEV_RESOURCE;
        }

        if (__send_request(bd->rq) < 0) {
                spin_unlock_irqrestore(&port->vio.lock, flags);
                return BLK_STS_IOERR;
        }

        spin_unlock_irqrestore(&port->vio.lock, flags);
        return BLK_STS_OK;
}

static int generic_request(struct vdc_port *port, u8 op, void *buf, int len)
{
        struct vio_dring_state *dr;
        struct vio_completion comp;
        struct vio_disk_desc *desc;
        unsigned int map_perm;
        unsigned long flags;
        int op_len, err;
        void *req_buf;

        if (!(((u64)1 << (u64)op) & port->operations))
                return -EOPNOTSUPP;

        switch (op) {
        case VD_OP_BREAD:
        case VD_OP_BWRITE:
        default:
                return -EINVAL;

        case VD_OP_FLUSH:
                op_len = 0;
                map_perm = 0;
                break;

        case VD_OP_GET_WCE:
                op_len = sizeof(u32);
                map_perm = LDC_MAP_W;
                break;

        case VD_OP_SET_WCE:
                op_len = sizeof(u32);
                map_perm = LDC_MAP_R;
                break;

        case VD_OP_GET_VTOC:
                op_len = sizeof(struct vio_disk_vtoc);
                map_perm = LDC_MAP_W;
                break;

        case VD_OP_SET_VTOC:
                op_len = sizeof(struct vio_disk_vtoc);
                map_perm = LDC_MAP_R;
                break;

        case VD_OP_GET_DISKGEOM:
                op_len = sizeof(struct vio_disk_geom);
                map_perm = LDC_MAP_W;
                break;

        case VD_OP_SET_DISKGEOM:
                op_len = sizeof(struct vio_disk_geom);
                map_perm = LDC_MAP_R;
                break;

        case VD_OP_SCSICMD:
                op_len = 16;
                map_perm = LDC_MAP_RW;
                break;

        case VD_OP_GET_DEVID:
                op_len = sizeof(struct vio_disk_devid);
                map_perm = LDC_MAP_W;
                break;

        case VD_OP_GET_EFI:
        case VD_OP_SET_EFI:
                return -EOPNOTSUPP;
        };

        map_perm |= LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;

        op_len = (op_len + 7) & ~7;
        req_buf = kzalloc(op_len, GFP_KERNEL);
        if (!req_buf)
                return -ENOMEM;

        if (len > op_len)
                len = op_len;

        if (map_perm & LDC_MAP_R)
                memcpy(req_buf, buf, len);

        spin_lock_irqsave(&port->vio.lock, flags);

        dr = &port->vio.drings[VIO_DRIVER_TX_RING];

        /* XXX If we want to use this code generically we have to
         * XXX handle TX ring exhaustion etc.
         */
        desc = vio_dring_cur(dr);

        err = ldc_map_single(port->vio.lp, req_buf, op_len,
                             desc->cookies, port->ring_cookies,
                             map_perm);
        if (err < 0) {
                spin_unlock_irqrestore(&port->vio.lock, flags);
                kfree(req_buf);
                return err;
        }

        init_completion(&comp.com);
        comp.waiting_for = WAITING_FOR_GEN_CMD;
        port->vio.cmp = &comp;

        desc->hdr.ack = VIO_ACK_ENABLE;
        desc->req_id = port->req_id;
        desc->operation = op;
        desc->slice = 0;
        desc->status = ~0;
        desc->offset = 0;
        desc->size = op_len;
        desc->ncookies = err;

        /* This has to be a non-SMP write barrier because we are writing
         * to memory which is shared with the peer LDOM.
         */
        wmb();
        desc->hdr.state = VIO_DESC_READY;

        err = __vdc_tx_trigger(port);
        if (err >= 0) {
                port->req_id++;
                dr->prod = vio_dring_next(dr, dr->prod);
                spin_unlock_irqrestore(&port->vio.lock, flags);

                wait_for_completion(&comp.com);
                err = comp.err;
        } else {
                port->vio.cmp = NULL;
                spin_unlock_irqrestore(&port->vio.lock, flags);
        }

        if (map_perm & LDC_MAP_W)
                memcpy(buf, req_buf, len);

        kfree(req_buf);

        return err;
}

static int vdc_alloc_tx_ring(struct vdc_port *port)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        unsigned long len, entry_size;
        int ncookies;
        void *dring;

        entry_size = sizeof(struct vio_disk_desc) +
                (sizeof(struct ldc_trans_cookie) * port->ring_cookies);
        len = (VDC_TX_RING_SIZE * entry_size);

        ncookies = VIO_MAX_RING_COOKIES;
        dring = ldc_alloc_exp_dring(port->vio.lp, len,
                                    dr->cookies, &ncookies,
                                    (LDC_MAP_SHADOW |
                                     LDC_MAP_DIRECT |
                                     LDC_MAP_RW));
        if (IS_ERR(dring))
                return PTR_ERR(dring);

        dr->base = dring;
        dr->entry_size = entry_size;
        dr->num_entries = VDC_TX_RING_SIZE;
        dr->prod = dr->cons = 0;
        dr->pending = VDC_TX_RING_SIZE;
        dr->ncookies = ncookies;

        return 0;
}

static void vdc_free_tx_ring(struct vdc_port *port)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];

        if (dr->base) {
                ldc_free_exp_dring(port->vio.lp, dr->base,
                                   (dr->entry_size * dr->num_entries),
                                   dr->cookies, dr->ncookies);
                dr->base = NULL;
                dr->entry_size = 0;
                dr->num_entries = 0;
                dr->pending = 0;
                dr->ncookies = 0;
        }
}

static int vdc_port_up(struct vdc_port *port)
{
        struct vio_completion comp;

        init_completion(&comp.com);
        comp.err = 0;
        comp.waiting_for = WAITING_FOR_LINK_UP;
        port->vio.cmp = &comp;

        vio_port_up(&port->vio);
        wait_for_completion(&comp.com);
        return comp.err;
}

static void vdc_port_down(struct vdc_port *port)
{
        ldc_disconnect(port->vio.lp);
        ldc_unbind(port->vio.lp);
        vdc_free_tx_ring(port);
        vio_ldc_free(&port->vio);
}

static const struct blk_mq_ops vdc_mq_ops = {
        .queue_rq       = vdc_queue_rq,
};

static void cleanup_queue(struct request_queue *q)
{
        struct vdc_port *port = q->queuedata;

        blk_cleanup_queue(q);
        blk_mq_free_tag_set(&port->tag_set);
}

static struct request_queue *init_queue(struct vdc_port *port)
{
        struct request_queue *q;

        q = blk_mq_init_sq_queue(&port->tag_set, &vdc_mq_ops, VDC_TX_RING_SIZE,
                                        BLK_MQ_F_SHOULD_MERGE);
        if (IS_ERR(q))
                return q;

        q->queuedata = port;
        return q;
}

static int probe_disk(struct vdc_port *port)
{
        struct request_queue *q;
        struct gendisk *g;
        int err;

        err = vdc_port_up(port);
        if (err)
                return err;

        /* Using version 1.2 means vdisk_phys_blksz should be set unless the
         * disk is reserved by another system.
         */
        if (vdc_version_supported(port, 1, 2) && !port->vdisk_phys_blksz)
                return -ENODEV;

        if (vdc_version_supported(port, 1, 1)) {
                /* vdisk_size should be set during the handshake, if it wasn't
                 * then the underlying disk is reserved by another system
                 */
                if (port->vdisk_size == -1)
                        return -ENODEV;
        } else {
                struct vio_disk_geom geom;

                err = generic_request(port, VD_OP_GET_DISKGEOM,
                                      &geom, sizeof(geom));
                if (err < 0) {
                        printk(KERN_ERR PFX "VD_OP_GET_DISKGEOM returns "
                               "error %d\n", err);
                        return err;
                }
                port->vdisk_size = ((u64)geom.num_cyl *
                                    (u64)geom.num_hd *
                                    (u64)geom.num_sec);
        }

        q = init_queue(port);
        if (IS_ERR(q)) {
                printk(KERN_ERR PFX "%s: Could not allocate queue.\n",
                       port->vio.name);
                return PTR_ERR(q);
        }
        g = alloc_disk(1 << PARTITION_SHIFT);
        if (!g) {
                printk(KERN_ERR PFX "%s: Could not allocate gendisk.\n",
                       port->vio.name);
                cleanup_queue(q);
                return -ENOMEM;
        }

        port->disk = g;

        /* Each segment in a request is up to an aligned page in size. */
        blk_queue_segment_boundary(q, PAGE_SIZE - 1);
        blk_queue_max_segment_size(q, PAGE_SIZE);

        blk_queue_max_segments(q, port->ring_cookies);
        blk_queue_max_hw_sectors(q, port->max_xfer_size);
        g->major = vdc_major;
        g->first_minor = port->vio.vdev->dev_no << PARTITION_SHIFT;
        strcpy(g->disk_name, port->disk_name);

        g->fops = &vdc_fops;
        g->queue = q;
        g->private_data = port;

        set_capacity(g, port->vdisk_size);

        if (vdc_version_supported(port, 1, 1)) {
                switch (port->vdisk_mtype) {
                case VD_MEDIA_TYPE_CD:
                        pr_info(PFX "Virtual CDROM %s\n", port->disk_name);
                        g->flags |= GENHD_FL_CD;
                        g->flags |= GENHD_FL_REMOVABLE;
                        set_disk_ro(g, 1);
                        break;

                case VD_MEDIA_TYPE_DVD:
                        pr_info(PFX "Virtual DVD %s\n", port->disk_name);
                        g->flags |= GENHD_FL_CD;
                        g->flags |= GENHD_FL_REMOVABLE;
                        set_disk_ro(g, 1);
                        break;

                case VD_MEDIA_TYPE_FIXED:
                        pr_info(PFX "Virtual Hard disk %s\n", port->disk_name);
                        break;
                }
        }

        blk_queue_physical_block_size(q, port->vdisk_phys_blksz);

        pr_info(PFX "%s: %u sectors (%u MB) protocol %d.%d\n",
               g->disk_name,
               port->vdisk_size, (port->vdisk_size >> (20 - 9)),
               port->vio.ver.major, port->vio.ver.minor);

        device_add_disk(&port->vio.vdev->dev, g, NULL);

        return 0;
}

static struct ldc_channel_config vdc_ldc_cfg = {
        .event          = vdc_event,
        .mtu            = 64,
        .mode           = LDC_MODE_UNRELIABLE,
};

static struct vio_driver_ops vdc_vio_ops = {
        .send_attr              = vdc_send_attr,
        .handle_attr            = vdc_handle_attr,
        .handshake_complete     = vdc_handshake_complete,
};

static void print_version(void)
{
        static int version_printed;

        if (version_printed++ == 0)
                printk(KERN_INFO "%s", version);
}

struct vdc_check_port_data {
        int     dev_no;
        char    *type;
};

static int vdc_device_probed(struct device *dev, void *arg)
{
        struct vio_dev *vdev = to_vio_dev(dev);
        struct vdc_check_port_data *port_data;

        port_data = (struct vdc_check_port_data *)arg;

        if ((vdev->dev_no == port_data->dev_no) &&
            (!(strcmp((char *)&vdev->type, port_data->type))) &&
                dev_get_drvdata(dev)) {
                /* This device has already been configured
                 * by vdc_port_probe()
                 */
                return 1;
        } else {
                return 0;
        }
}

/* Determine whether the VIO device is part of an mpgroup
 * by locating all the virtual-device-port nodes associated
 * with the parent virtual-device node for the VIO device
 * and checking whether any of these nodes are vdc-ports
 * which have already been configured.
 *
 * Returns true if this device is part of an mpgroup and has
 * already been probed.
 */
static bool vdc_port_mpgroup_check(struct vio_dev *vdev)
{
        struct vdc_check_port_data port_data;
        struct device *dev;

        port_data.dev_no = vdev->dev_no;
        port_data.type = (char *)&vdev->type;

        dev = device_find_child(vdev->dev.parent, &port_data,
                                vdc_device_probed);

        if (dev)
                return true;

        return false;
}

static int vdc_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)
{
        struct mdesc_handle *hp;
        struct vdc_port *port;
        int err;
        const u64 *ldc_timeout;

        print_version();

        hp = mdesc_grab();

        err = -ENODEV;
        if ((vdev->dev_no << PARTITION_SHIFT) & ~(u64)MINORMASK) {
                printk(KERN_ERR PFX "Port id [%llu] too large.\n",
                       vdev->dev_no);
                goto err_out_release_mdesc;
        }

        /* Check if this device is part of an mpgroup */
        if (vdc_port_mpgroup_check(vdev)) {
                printk(KERN_WARNING
                        "VIO: Ignoring extra vdisk port %s",
                        dev_name(&vdev->dev));
                goto err_out_release_mdesc;
        }

        port = kzalloc(sizeof(*port), GFP_KERNEL);
        err = -ENOMEM;
        if (!port) {
                printk(KERN_ERR PFX "Cannot allocate vdc_port.\n");
                goto err_out_release_mdesc;
        }

        if (vdev->dev_no >= 26)
                snprintf(port->disk_name, sizeof(port->disk_name),
                         VDCBLK_NAME "%c%c",
                         'a' + ((int)vdev->dev_no / 26) - 1,
                         'a' + ((int)vdev->dev_no % 26));
        else
                snprintf(port->disk_name, sizeof(port->disk_name),
                         VDCBLK_NAME "%c", 'a' + ((int)vdev->dev_no % 26));
        port->vdisk_size = -1;

        /* Actual wall time may be double due to do_generic_file_read() doing
         * a readahead I/O first, and once that fails it will try to read a
         * single page.
         */
        ldc_timeout = mdesc_get_property(hp, vdev->mp, "vdc-timeout", NULL);
        port->ldc_timeout = ldc_timeout ? *ldc_timeout : 0;
        INIT_DELAYED_WORK(&port->ldc_reset_timer_work, vdc_ldc_reset_timer_work);
        INIT_WORK(&port->ldc_reset_work, vdc_ldc_reset_work);

        err = vio_driver_init(&port->vio, vdev, VDEV_DISK,
                              vdc_versions, ARRAY_SIZE(vdc_versions),
                              &vdc_vio_ops, port->disk_name);
        if (err)
                goto err_out_free_port;

        port->vdisk_block_size = VDC_DEFAULT_BLK_SIZE;
        port->max_xfer_size = MAX_XFER_SIZE;
        port->ring_cookies = MAX_RING_COOKIES;

        err = vio_ldc_alloc(&port->vio, &vdc_ldc_cfg, port);
        if (err)
                goto err_out_free_port;

        err = vdc_alloc_tx_ring(port);
        if (err)
                goto err_out_free_ldc;

        err = probe_disk(port);
        if (err)
                goto err_out_free_tx_ring;

        /* Note that the device driver_data is used to determine
         * whether the port has been probed.
         */
        dev_set_drvdata(&vdev->dev, port);

        mdesc_release(hp);

        return 0;

err_out_free_tx_ring:
        vdc_free_tx_ring(port);

err_out_free_ldc:
        vio_ldc_free(&port->vio);

err_out_free_port:
        kfree(port);

err_out_release_mdesc:
        mdesc_release(hp);
        return err;
}

static int vdc_port_remove(struct vio_dev *vdev)
{
        struct vdc_port *port = dev_get_drvdata(&vdev->dev);

        if (port) {
                blk_mq_stop_hw_queues(port->disk->queue);

                flush_work(&port->ldc_reset_work);
                cancel_delayed_work_sync(&port->ldc_reset_timer_work);
                del_timer_sync(&port->vio.timer);

                del_gendisk(port->disk);
                cleanup_queue(port->disk->queue);
                put_disk(port->disk);
                port->disk = NULL;

                vdc_free_tx_ring(port);
                vio_ldc_free(&port->vio);

                dev_set_drvdata(&vdev->dev, NULL);

                kfree(port);
        }
        return 0;
}

static void vdc_requeue_inflight(struct vdc_port *port)
{
        struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
        u32 idx;

        for (idx = dr->cons; idx != dr->prod; idx = vio_dring_next(dr, idx)) {
                struct vio_disk_desc *desc = vio_dring_entry(dr, idx);
                struct vdc_req_entry *rqe = &port->rq_arr[idx];
                struct request *req;

                ldc_unmap(port->vio.lp, desc->cookies, desc->ncookies);
                desc->hdr.state = VIO_DESC_FREE;
                dr->cons = vio_dring_next(dr, idx);

                req = rqe->req;
                if (req == NULL) {
                        vdc_end_special(port, desc);
                        continue;
                }

                rqe->req = NULL;
                blk_mq_requeue_request(req, false);
        }
}

static void vdc_queue_drain(struct vdc_port *port)
{
        struct request_queue *q = port->disk->queue;

        /*
         * Mark the queue as draining, then freeze/quiesce to ensure
         * that all existing requests are seen in ->queue_rq() and killed
         */
        port->drain = 1;
        spin_unlock_irq(&port->vio.lock);

        blk_mq_freeze_queue(q);
        blk_mq_quiesce_queue(q);

        spin_lock_irq(&port->vio.lock);
        port->drain = 0;
        blk_mq_unquiesce_queue(q);
        blk_mq_unfreeze_queue(q);
}

static void vdc_ldc_reset_timer_work(struct work_struct *work)
{
        struct vdc_port *port;
        struct vio_driver_state *vio;

        port = container_of(work, struct vdc_port, ldc_reset_timer_work.work);
        vio = &port->vio;

        spin_lock_irq(&vio->lock);
        if (!(port->vio.hs_state & VIO_HS_COMPLETE)) {
                pr_warn(PFX "%s ldc down %llu seconds, draining queue\n",
                        port->disk_name, port->ldc_timeout);
                vdc_queue_drain(port);
                vdc_blk_queue_start(port);
        }
        spin_unlock_irq(&vio->lock);
}

static void vdc_ldc_reset_work(struct work_struct *work)
{
        struct vdc_port *port;
        struct vio_driver_state *vio;
        unsigned long flags;

        port = container_of(work, struct vdc_port, ldc_reset_work);
        vio = &port->vio;

        spin_lock_irqsave(&vio->lock, flags);
        vdc_ldc_reset(port);
        spin_unlock_irqrestore(&vio->lock, flags);
}

static void vdc_ldc_reset(struct vdc_port *port)
{
        int err;

        assert_spin_locked(&port->vio.lock);

        pr_warn(PFX "%s ldc link reset\n", port->disk_name);
        blk_mq_stop_hw_queues(port->disk->queue);
        vdc_requeue_inflight(port);
        vdc_port_down(port);

        err = vio_ldc_alloc(&port->vio, &vdc_ldc_cfg, port);
        if (err) {
                pr_err(PFX "%s vio_ldc_alloc:%d\n", port->disk_name, err);
                return;
        }

        err = vdc_alloc_tx_ring(port);
        if (err) {
                pr_err(PFX "%s vio_alloc_tx_ring:%d\n", port->disk_name, err);
                goto err_free_ldc;
        }

        if (port->ldc_timeout)
                mod_delayed_work(system_wq, &port->ldc_reset_timer_work,
                          round_jiffies(jiffies + HZ * port->ldc_timeout));
        mod_timer(&port->vio.timer, round_jiffies(jiffies + HZ));
        return;

err_free_ldc:
        vio_ldc_free(&port->vio);
}

static const struct vio_device_id vdc_port_match[] = {
        {
                .type = "vdc-port",
        },
        {},
};
MODULE_DEVICE_TABLE(vio, vdc_port_match);

static struct vio_driver vdc_port_driver = {
        .id_table       = vdc_port_match,
        .probe          = vdc_port_probe,
        .remove         = vdc_port_remove,
        .name           = "vdc_port",
};

static int __init vdc_init(void)
{
        int err;

        sunvdc_wq = alloc_workqueue("sunvdc", 0, 0);
        if (!sunvdc_wq)
                return -ENOMEM;

        err = register_blkdev(0, VDCBLK_NAME);
        if (err < 0)
                goto out_free_wq;

        vdc_major = err;

        err = vio_register_driver(&vdc_port_driver);
        if (err)
                goto out_unregister_blkdev;

        return 0;

out_unregister_blkdev:
        unregister_blkdev(vdc_major, VDCBLK_NAME);
        vdc_major = 0;

out_free_wq:
        destroy_workqueue(sunvdc_wq);
        return err;
}

static void __exit vdc_exit(void)
{
        vio_unregister_driver(&vdc_port_driver);
        unregister_blkdev(vdc_major, VDCBLK_NAME);
        destroy_workqueue(sunvdc_wq);
}

module_init(vdc_init);
module_exit(vdc_exit);