// SPDX-License-Identifier: GPL-2.0
/*
 * ccw based virtio transport
 *
 * Copyright IBM Corp. 2012, 2014
 *
 *    Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
 */

#include <linux/kernel_stat.h>
#include <linux/init.h>
#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/virtio_ring.h>
#include <linux/pfn.h>
#include <linux/async.h>
#include <linux/wait.h>
#include <linux/list.h>
#include <linux/bitops.h>
#include <linux/moduleparam.h>
#include <linux/io.h>
#include <linux/kvm_para.h>
#include <linux/notifier.h>
#include <asm/diag.h>
#include <asm/setup.h>
#include <asm/irq.h>
#include <asm/cio.h>
#include <asm/ccwdev.h>
#include <asm/virtio-ccw.h>
#include <asm/isc.h>
#include <asm/airq.h>

/*
 * virtio related functions
 */

struct vq_config_block {
        __u16 index;
        __u16 num;
} __packed;

#define VIRTIO_CCW_CONFIG_SIZE 0x100
/* same as PCI config space size, should be enough for all drivers */

struct vcdev_dma_area {
        unsigned long indicators;
        unsigned long indicators2;
        struct vq_config_block config_block;
        __u8 status;
};

struct virtio_ccw_device {
        struct virtio_device vdev;
        __u8 config[VIRTIO_CCW_CONFIG_SIZE];
        struct ccw_device *cdev;
        __u32 curr_io;
        int err;
        unsigned int revision; /* Transport revision */
        wait_queue_head_t wait_q;
        spinlock_t lock;
        rwlock_t irq_lock;
        struct mutex io_lock; /* Serializes I/O requests */
        struct list_head virtqueues;
        bool is_thinint;
        bool going_away;
        bool device_lost;
        unsigned int config_ready;
        void *airq_info;
        struct vcdev_dma_area *dma_area;
};

static inline unsigned long *indicators(struct virtio_ccw_device *vcdev)
{
        return &vcdev->dma_area->indicators;
}

static inline unsigned long *indicators2(struct virtio_ccw_device *vcdev)
{
        return &vcdev->dma_area->indicators2;
}

struct vq_info_block_legacy {
        __u64 queue;
        __u32 align;
        __u16 index;
        __u16 num;
} __packed;

struct vq_info_block {
        __u64 desc;
        __u32 res0;
        __u16 index;
        __u16 num;
        __u64 avail;
        __u64 used;
} __packed;

struct virtio_feature_desc {
        __le32 features;
        __u8 index;
} __packed;

struct virtio_thinint_area {
        unsigned long summary_indicator;
        unsigned long indicator;
        u64 bit_nr;
        u8 isc;
} __packed;

struct virtio_rev_info {
        __u16 revision;
        __u16 length;
        __u8 data[];
};

/* the highest virtio-ccw revision we support */
#define VIRTIO_CCW_REV_MAX 2

struct virtio_ccw_vq_info {
        struct virtqueue *vq;
        int num;
        union {
                struct vq_info_block s;
                struct vq_info_block_legacy l;
        } *info_block;
        int bit_nr;
        struct list_head node;
        long cookie;
};

#define VIRTIO_AIRQ_ISC IO_SCH_ISC /* inherit from subchannel */

#define VIRTIO_IV_BITS (L1_CACHE_BYTES * 8)
#define MAX_AIRQ_AREAS 20

static int virtio_ccw_use_airq = 1;

struct airq_info {
        rwlock_t lock;
        u8 summary_indicator_idx;
        struct airq_struct airq;
        struct airq_iv *aiv;
};
static struct airq_info *airq_areas[MAX_AIRQ_AREAS];
static DEFINE_MUTEX(airq_areas_lock);

static u8 *summary_indicators;

static inline u8 *get_summary_indicator(struct airq_info *info)
{
        return summary_indicators + info->summary_indicator_idx;
}

#define CCW_CMD_SET_VQ 0x13
#define CCW_CMD_VDEV_RESET 0x33
#define CCW_CMD_SET_IND 0x43
#define CCW_CMD_SET_CONF_IND 0x53
#define CCW_CMD_READ_FEAT 0x12
#define CCW_CMD_WRITE_FEAT 0x11
#define CCW_CMD_READ_CONF 0x22
#define CCW_CMD_WRITE_CONF 0x21
#define CCW_CMD_WRITE_STATUS 0x31
#define CCW_CMD_READ_VQ_CONF 0x32
#define CCW_CMD_READ_STATUS 0x72
#define CCW_CMD_SET_IND_ADAPTER 0x73
#define CCW_CMD_SET_VIRTIO_REV 0x83

#define VIRTIO_CCW_DOING_SET_VQ 0x00010000
#define VIRTIO_CCW_DOING_RESET 0x00040000
#define VIRTIO_CCW_DOING_READ_FEAT 0x00080000
#define VIRTIO_CCW_DOING_WRITE_FEAT 0x00100000
#define VIRTIO_CCW_DOING_READ_CONFIG 0x00200000
#define VIRTIO_CCW_DOING_WRITE_CONFIG 0x00400000
#define VIRTIO_CCW_DOING_WRITE_STATUS 0x00800000
#define VIRTIO_CCW_DOING_SET_IND 0x01000000
#define VIRTIO_CCW_DOING_READ_VQ_CONF 0x02000000
#define VIRTIO_CCW_DOING_SET_CONF_IND 0x04000000
#define VIRTIO_CCW_DOING_SET_IND_ADAPTER 0x08000000
#define VIRTIO_CCW_DOING_SET_VIRTIO_REV 0x10000000
#define VIRTIO_CCW_DOING_READ_STATUS 0x20000000
#define VIRTIO_CCW_INTPARM_MASK 0xffff0000

static struct virtio_ccw_device *to_vc_device(struct virtio_device *vdev)
{
        return container_of(vdev, struct virtio_ccw_device, vdev);
}

static void drop_airq_indicator(struct virtqueue *vq, struct airq_info *info)
{
        unsigned long i, flags;

        write_lock_irqsave(&info->lock, flags);
        for (i = 0; i < airq_iv_end(info->aiv); i++) {
                if (vq == (void *)airq_iv_get_ptr(info->aiv, i)) {
                        airq_iv_free_bit(info->aiv, i);
                        airq_iv_set_ptr(info->aiv, i, 0);
                        break;
                }
        }
        write_unlock_irqrestore(&info->lock, flags);
}

static void virtio_airq_handler(struct airq_struct *airq, bool floating)
{
        struct airq_info *info = container_of(airq, struct airq_info, airq);
        unsigned long ai;

        inc_irq_stat(IRQIO_VAI);
        read_lock(&info->lock);
        /* Walk through indicators field, summary indicator active. */
        for (ai = 0;;) {
                ai = airq_iv_scan(info->aiv, ai, airq_iv_end(info->aiv));
                if (ai == -1UL)
                        break;
                vring_interrupt(0, (void *)airq_iv_get_ptr(info->aiv, ai));
        }
        *(get_summary_indicator(info)) = 0;
        smp_wmb();
        /* Walk through indicators field, summary indicator not active. */
        for (ai = 0;;) {
                ai = airq_iv_scan(info->aiv, ai, airq_iv_end(info->aiv));
                if (ai == -1UL)
                        break;
                vring_interrupt(0, (void *)airq_iv_get_ptr(info->aiv, ai));
        }
        read_unlock(&info->lock);
}

static struct airq_info *new_airq_info(int index)
{
        struct airq_info *info;
        int rc;

        info = kzalloc(sizeof(*info), GFP_KERNEL);
        if (!info)
                return NULL;
        rwlock_init(&info->lock);
        info->aiv = airq_iv_create(VIRTIO_IV_BITS, AIRQ_IV_ALLOC | AIRQ_IV_PTR
                                   | AIRQ_IV_CACHELINE);
        if (!info->aiv) {
                kfree(info);
                return NULL;
        }
        info->airq.handler = virtio_airq_handler;
        info->summary_indicator_idx = index;
        info->airq.lsi_ptr = get_summary_indicator(info);
        info->airq.lsi_mask = 0xff;
        info->airq.isc = VIRTIO_AIRQ_ISC;
        rc = register_adapter_interrupt(&info->airq);
        if (rc) {
                airq_iv_release(info->aiv);
                kfree(info);
                return NULL;
        }
        return info;
}

static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,
                                        u64 *first, void **airq_info)
{
        int i, j;
        struct airq_info *info;
        unsigned long indicator_addr = 0;
        unsigned long bit, flags;

        for (i = 0; i < MAX_AIRQ_AREAS && !indicator_addr; i++) {
                mutex_lock(&airq_areas_lock);
                if (!airq_areas[i])
                        airq_areas[i] = new_airq_info(i);
                info = airq_areas[i];
                mutex_unlock(&airq_areas_lock);
                if (!info)
                        return 0;
                write_lock_irqsave(&info->lock, flags);
                bit = airq_iv_alloc(info->aiv, nvqs);
                if (bit == -1UL) {
                        /* Not enough vacancies. */
                        write_unlock_irqrestore(&info->lock, flags);
                        continue;
                }
                *first = bit;
                *airq_info = info;
                indicator_addr = (unsigned long)info->aiv->vector;
                for (j = 0; j < nvqs; j++) {
                        airq_iv_set_ptr(info->aiv, bit + j,
                                        (unsigned long)vqs[j]);
                }
                write_unlock_irqrestore(&info->lock, flags);
        }
        return indicator_addr;
}

static void virtio_ccw_drop_indicators(struct virtio_ccw_device *vcdev)
{
        struct virtio_ccw_vq_info *info;

        if (!vcdev->airq_info)
                return;
        list_for_each_entry(info, &vcdev->virtqueues, node)
                drop_airq_indicator(info->vq, vcdev->airq_info);
}

static int doing_io(struct virtio_ccw_device *vcdev, __u32 flag)
{
        unsigned long flags;
        __u32 ret;

        spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
        if (vcdev->err)
                ret = 0;
        else
                ret = vcdev->curr_io & flag;
        spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
        return ret;
}

static int ccw_io_helper(struct virtio_ccw_device *vcdev,
                         struct ccw1 *ccw, __u32 intparm)
{
        int ret;
        unsigned long flags;
        int flag = intparm & VIRTIO_CCW_INTPARM_MASK;

        mutex_lock(&vcdev->io_lock);
        do {
                spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
                ret = ccw_device_start(vcdev->cdev, ccw, intparm, 0, 0);
                if (!ret) {
                        if (!vcdev->curr_io)
                                vcdev->err = 0;
                        vcdev->curr_io |= flag;
                }
                spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
                cpu_relax();
        } while (ret == -EBUSY);
        wait_event(vcdev->wait_q, doing_io(vcdev, flag) == 0);
        ret = ret ? ret : vcdev->err;
        mutex_unlock(&vcdev->io_lock);
        return ret;
}

static void virtio_ccw_drop_indicator(struct virtio_ccw_device *vcdev,
                                      struct ccw1 *ccw)
{
        int ret;
        unsigned long *indicatorp = NULL;
        struct virtio_thinint_area *thinint_area = NULL;
        struct airq_info *airq_info = vcdev->airq_info;

        if (vcdev->is_thinint) {
                thinint_area = ccw_device_dma_zalloc(vcdev->cdev,
                                                     sizeof(*thinint_area));
                if (!thinint_area)
                        return;
                thinint_area->summary_indicator =
                        (unsigned long) get_summary_indicator(airq_info);
                thinint_area->isc = VIRTIO_AIRQ_ISC;
                ccw->cmd_code = CCW_CMD_SET_IND_ADAPTER;
                ccw->count = sizeof(*thinint_area);
                ccw->cda = (__u32)(unsigned long) thinint_area;
        } else {
                /* payload is the address of the indicators */
                indicatorp = ccw_device_dma_zalloc(vcdev->cdev,
                                                   sizeof(indicators(vcdev)));
                if (!indicatorp)
                        return;
                *indicatorp = 0;
                ccw->cmd_code = CCW_CMD_SET_IND;
                ccw->count = sizeof(indicators(vcdev));
                ccw->cda = (__u32)(unsigned long) indicatorp;
        }
        /* Deregister indicators from host. */
        *indicators(vcdev) = 0;
        ccw->flags = 0;
        ret = ccw_io_helper(vcdev, ccw,
                            vcdev->is_thinint ?
                            VIRTIO_CCW_DOING_SET_IND_ADAPTER :
                            VIRTIO_CCW_DOING_SET_IND);
        if (ret && (ret != -ENODEV))
                dev_info(&vcdev->cdev->dev,
                         "Failed to deregister indicators (%d)\n", ret);
        else if (vcdev->is_thinint)
                virtio_ccw_drop_indicators(vcdev);
        ccw_device_dma_free(vcdev->cdev, indicatorp, sizeof(indicators(vcdev)));
        ccw_device_dma_free(vcdev->cdev, thinint_area, sizeof(*thinint_area));
}

static bool virtio_ccw_kvm_notify(struct virtqueue *vq)
{
        struct virtio_ccw_vq_info *info = vq->priv;
        struct virtio_ccw_device *vcdev;
        struct subchannel_id schid;

        vcdev = to_vc_device(info->vq->vdev);
        ccw_device_get_schid(vcdev->cdev, &schid);
        BUILD_BUG_ON(sizeof(struct subchannel_id) != sizeof(unsigned int));
        info->cookie = kvm_hypercall3(KVM_S390_VIRTIO_CCW_NOTIFY,
                                      *((unsigned int *)&schid),
                                      vq->index, info->cookie);
        if (info->cookie < 0)
                return false;
        return true;
}

static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
                                   struct ccw1 *ccw, int index)
{
        int ret;

        vcdev->dma_area->config_block.index = index;
        ccw->cmd_code = CCW_CMD_READ_VQ_CONF;
        ccw->flags = 0;
        ccw->count = sizeof(struct vq_config_block);
        ccw->cda = (__u32)(unsigned long)(&vcdev->dma_area->config_block);
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
        if (ret)
                return ret;
        return vcdev->dma_area->config_block.num ?: -ENOENT;
}

static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vq->vdev);
        struct virtio_ccw_vq_info *info = vq->priv;
        unsigned long flags;
        int ret;
        unsigned int index = vq->index;

        /* Remove from our list. */
        spin_lock_irqsave(&vcdev->lock, flags);
        list_del(&info->node);
        spin_unlock_irqrestore(&vcdev->lock, flags);

        /* Release from host. */
        if (vcdev->revision == 0) {
                info->info_block->l.queue = 0;
                info->info_block->l.align = 0;
                info->info_block->l.index = index;
                info->info_block->l.num = 0;
                ccw->count = sizeof(info->info_block->l);
        } else {
                info->info_block->s.desc = 0;
                info->info_block->s.index = index;
                info->info_block->s.num = 0;
                info->info_block->s.avail = 0;
                info->info_block->s.used = 0;
                ccw->count = sizeof(info->info_block->s);
        }
        ccw->cmd_code = CCW_CMD_SET_VQ;
        ccw->flags = 0;
        ccw->cda = (__u32)(unsigned long)(info->info_block);
        ret = ccw_io_helper(vcdev, ccw,
                            VIRTIO_CCW_DOING_SET_VQ | index);
        /*
         * -ENODEV isn't considered an error: The device is gone anyway.
         * This may happen on device detach.
         */
        if (ret && (ret != -ENODEV))
                dev_warn(&vq->vdev->dev, "Error %d while deleting queue %d\n",
                         ret, index);

        vring_del_virtqueue(vq);
        ccw_device_dma_free(vcdev->cdev, info->info_block,
                            sizeof(*info->info_block));
        kfree(info);
}

static void virtio_ccw_del_vqs(struct virtio_device *vdev)
{
        struct virtqueue *vq, *n;
        struct ccw1 *ccw;
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return;

        virtio_ccw_drop_indicator(vcdev, ccw);

        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
                virtio_ccw_del_vq(vq, ccw);

        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
}

static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
                                             int i, vq_callback_t *callback,
                                             const char *name, bool ctx,
                                             struct ccw1 *ccw)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        int err;
        struct virtqueue *vq = NULL;
        struct virtio_ccw_vq_info *info;
        u64 queue;
        unsigned long flags;
        bool may_reduce;

        /* Allocate queue. */
        info = kzalloc(sizeof(struct virtio_ccw_vq_info), GFP_KERNEL);
        if (!info) {
                dev_warn(&vcdev->cdev->dev, "no info\n");
                err = -ENOMEM;
                goto out_err;
        }
        info->info_block = ccw_device_dma_zalloc(vcdev->cdev,
                                                 sizeof(*info->info_block));
        if (!info->info_block) {
                dev_warn(&vcdev->cdev->dev, "no info block\n");
                err = -ENOMEM;
                goto out_err;
        }
        info->num = virtio_ccw_read_vq_conf(vcdev, ccw, i);
        if (info->num < 0) {
                err = info->num;
                goto out_err;
        }
        may_reduce = vcdev->revision > 0;
        vq = vring_create_virtqueue(i, info->num, KVM_VIRTIO_CCW_RING_ALIGN,
                                    vdev, true, may_reduce, ctx,
                                    virtio_ccw_kvm_notify, callback, name);

        if (!vq) {
                /* For now, we fail if we can't get the requested size. */
                dev_warn(&vcdev->cdev->dev, "no vq\n");
                err = -ENOMEM;
                goto out_err;
        }
        /* it may have been reduced */
        info->num = virtqueue_get_vring_size(vq);

        /* Register it with the host. */
        queue = virtqueue_get_desc_addr(vq);
        if (vcdev->revision == 0) {
                info->info_block->l.queue = queue;
                info->info_block->l.align = KVM_VIRTIO_CCW_RING_ALIGN;
                info->info_block->l.index = i;
                info->info_block->l.num = info->num;
                ccw->count = sizeof(info->info_block->l);
        } else {
                info->info_block->s.desc = queue;
                info->info_block->s.index = i;
                info->info_block->s.num = info->num;
                info->info_block->s.avail = (__u64)virtqueue_get_avail_addr(vq);
                info->info_block->s.used = (__u64)virtqueue_get_used_addr(vq);
                ccw->count = sizeof(info->info_block->s);
        }
        ccw->cmd_code = CCW_CMD_SET_VQ;
        ccw->flags = 0;
        ccw->cda = (__u32)(unsigned long)(info->info_block);
        err = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_SET_VQ | i);
        if (err) {
                dev_warn(&vcdev->cdev->dev, "SET_VQ failed\n");
                goto out_err;
        }

        info->vq = vq;
        vq->priv = info;

        /* Save it to our list. */
        spin_lock_irqsave(&vcdev->lock, flags);
        list_add(&info->node, &vcdev->virtqueues);
        spin_unlock_irqrestore(&vcdev->lock, flags);

        return vq;

out_err:
        if (vq)
                vring_del_virtqueue(vq);
        if (info) {
                ccw_device_dma_free(vcdev->cdev, info->info_block,
                                    sizeof(*info->info_block));
        }
        kfree(info);
        return ERR_PTR(err);
}

static int virtio_ccw_register_adapter_ind(struct virtio_ccw_device *vcdev,
                                           struct virtqueue *vqs[], int nvqs,
                                           struct ccw1 *ccw)
{
        int ret;
        struct virtio_thinint_area *thinint_area = NULL;
        struct airq_info *info;

        thinint_area = ccw_device_dma_zalloc(vcdev->cdev,
                                             sizeof(*thinint_area));
        if (!thinint_area) {
                ret = -ENOMEM;
                goto out;
        }
        /* Try to get an indicator. */
        thinint_area->indicator = get_airq_indicator(vqs, nvqs,
                                                     &thinint_area->bit_nr,
                                                     &vcdev->airq_info);
        if (!thinint_area->indicator) {
                ret = -ENOSPC;
                goto out;
        }
        info = vcdev->airq_info;
        thinint_area->summary_indicator =
                (unsigned long) get_summary_indicator(info);
        thinint_area->isc = VIRTIO_AIRQ_ISC;
        ccw->cmd_code = CCW_CMD_SET_IND_ADAPTER;
        ccw->flags = CCW_FLAG_SLI;
        ccw->count = sizeof(*thinint_area);
        ccw->cda = (__u32)(unsigned long)thinint_area;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_SET_IND_ADAPTER);
        if (ret) {
                if (ret == -EOPNOTSUPP) {
                        /*
                         * The host does not support adapter interrupts
                         * for virtio-ccw, stop trying.
                         */
                        virtio_ccw_use_airq = 0;
                        pr_info("Adapter interrupts unsupported on host\n");
                } else
                        dev_warn(&vcdev->cdev->dev,
                                 "enabling adapter interrupts = %d\n", ret);
                virtio_ccw_drop_indicators(vcdev);
        }
out:
        ccw_device_dma_free(vcdev->cdev, thinint_area, sizeof(*thinint_area));
        return ret;
}

static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
                               struct virtqueue *vqs[],
                               vq_callback_t *callbacks[],
                               const char * const names[],
                               const bool *ctx,
                               struct irq_affinity *desc)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        unsigned long *indicatorp = NULL;
        int ret, i, queue_idx = 0;
        struct ccw1 *ccw;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return -ENOMEM;

        for (i = 0; i < nvqs; ++i) {
                if (!names[i]) {
                        vqs[i] = NULL;
                        continue;
                }

                vqs[i] = virtio_ccw_setup_vq(vdev, queue_idx++, callbacks[i],
                                             names[i], ctx ? ctx[i] : false,
                                             ccw);
                if (IS_ERR(vqs[i])) {
                        ret = PTR_ERR(vqs[i]);
                        vqs[i] = NULL;
                        goto out;
                }
        }
        ret = -ENOMEM;
        /*
         * We need a data area under 2G to communicate. Our payload is
         * the address of the indicators.
        */
        indicatorp = ccw_device_dma_zalloc(vcdev->cdev,
                                           sizeof(indicators(vcdev)));
        if (!indicatorp)
                goto out;
        *indicatorp = (unsigned long) indicators(vcdev);
        if (vcdev->is_thinint) {
                ret = virtio_ccw_register_adapter_ind(vcdev, vqs, nvqs, ccw);
                if (ret)
                        /* no error, just fall back to legacy interrupts */
                        vcdev->is_thinint = false;
        }
        if (!vcdev->is_thinint) {
                /* Register queue indicators with host. */
                *indicators(vcdev) = 0;
                ccw->cmd_code = CCW_CMD_SET_IND;
                ccw->flags = 0;
                ccw->count = sizeof(indicators(vcdev));
                ccw->cda = (__u32)(unsigned long) indicatorp;
                ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_SET_IND);
                if (ret)
                        goto out;
        }
        /* Register indicators2 with host for config changes */
        *indicatorp = (unsigned long) indicators2(vcdev);
        *indicators2(vcdev) = 0;
        ccw->cmd_code = CCW_CMD_SET_CONF_IND;
        ccw->flags = 0;
        ccw->count = sizeof(indicators2(vcdev));
        ccw->cda = (__u32)(unsigned long) indicatorp;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_SET_CONF_IND);
        if (ret)
                goto out;

        if (indicatorp)
                ccw_device_dma_free(vcdev->cdev, indicatorp,
                                    sizeof(indicators(vcdev)));
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
        return 0;
out:
        if (indicatorp)
                ccw_device_dma_free(vcdev->cdev, indicatorp,
                                    sizeof(indicators(vcdev)));
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
        virtio_ccw_del_vqs(vdev);
        return ret;
}

static void virtio_ccw_reset(struct virtio_device *vdev)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        struct ccw1 *ccw;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return;

        /* Zero status bits. */
        vcdev->dma_area->status = 0;

        /* Send a reset ccw on device. */
        ccw->cmd_code = CCW_CMD_VDEV_RESET;
        ccw->flags = 0;
        ccw->count = 0;
        ccw->cda = 0;
        ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_RESET);
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
}

static u64 virtio_ccw_get_features(struct virtio_device *vdev)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        struct virtio_feature_desc *features;
        int ret;
        u64 rc;
        struct ccw1 *ccw;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return 0;

        features = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*features));
        if (!features) {
                rc = 0;
                goto out_free;
        }
        /* Read the feature bits from the host. */
        features->index = 0;
        ccw->cmd_code = CCW_CMD_READ_FEAT;
        ccw->flags = 0;
        ccw->count = sizeof(*features);
        ccw->cda = (__u32)(unsigned long)features;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_FEAT);
        if (ret) {
                rc = 0;
                goto out_free;
        }

        rc = le32_to_cpu(features->features);

        if (vcdev->revision == 0)
                goto out_free;

        /* Read second half of the feature bits from the host. */
        features->index = 1;
        ccw->cmd_code = CCW_CMD_READ_FEAT;
        ccw->flags = 0;
        ccw->count = sizeof(*features);
        ccw->cda = (__u32)(unsigned long)features;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_FEAT);
        if (ret == 0)
                rc |= (u64)le32_to_cpu(features->features) << 32;

out_free:
        ccw_device_dma_free(vcdev->cdev, features, sizeof(*features));
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
        return rc;
}

static void ccw_transport_features(struct virtio_device *vdev)
{
        /*
         * Currently nothing to do here.
         */
}

static int virtio_ccw_finalize_features(struct virtio_device *vdev)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        struct virtio_feature_desc *features;
        struct ccw1 *ccw;
        int ret;

        if (vcdev->revision >= 1 &&
            !__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
                dev_err(&vdev->dev, "virtio: device uses revision 1 "
                        "but does not have VIRTIO_F_VERSION_1\n");
                return -EINVAL;
        }

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return -ENOMEM;

        features = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*features));
        if (!features) {
                ret = -ENOMEM;
                goto out_free;
        }
        /* Give virtio_ring a chance to accept features. */
        vring_transport_features(vdev);

        /* Give virtio_ccw a chance to accept features. */
        ccw_transport_features(vdev);

        features->index = 0;
        features->features = cpu_to_le32((u32)vdev->features);
        /* Write the first half of the feature bits to the host. */
        ccw->cmd_code = CCW_CMD_WRITE_FEAT;
        ccw->flags = 0;
        ccw->count = sizeof(*features);
        ccw->cda = (__u32)(unsigned long)features;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);
        if (ret)
                goto out_free;

        if (vcdev->revision == 0)
                goto out_free;

        features->index = 1;
        features->features = cpu_to_le32(vdev->features >> 32);
        /* Write the second half of the feature bits to the host. */
        ccw->cmd_code = CCW_CMD_WRITE_FEAT;
        ccw->flags = 0;
        ccw->count = sizeof(*features);
        ccw->cda = (__u32)(unsigned long)features;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_FEAT);

out_free:
        ccw_device_dma_free(vcdev->cdev, features, sizeof(*features));
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));

        return ret;
}

static void virtio_ccw_get_config(struct virtio_device *vdev,
                                  unsigned int offset, void *buf, unsigned len)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        int ret;
        struct ccw1 *ccw;
        void *config_area;
        unsigned long flags;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return;

        config_area = ccw_device_dma_zalloc(vcdev->cdev,
                                            VIRTIO_CCW_CONFIG_SIZE);
        if (!config_area)
                goto out_free;

        /* Read the config area from the host. */
        ccw->cmd_code = CCW_CMD_READ_CONF;
        ccw->flags = 0;
        ccw->count = offset + len;
        ccw->cda = (__u32)(unsigned long)config_area;
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_CONFIG);
        if (ret)
                goto out_free;

        spin_lock_irqsave(&vcdev->lock, flags);
        memcpy(vcdev->config, config_area, offset + len);
        if (vcdev->config_ready < offset + len)
                vcdev->config_ready = offset + len;
        spin_unlock_irqrestore(&vcdev->lock, flags);
        if (buf)
                memcpy(buf, config_area + offset, len);

out_free:
        ccw_device_dma_free(vcdev->cdev, config_area, VIRTIO_CCW_CONFIG_SIZE);
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
}

static void virtio_ccw_set_config(struct virtio_device *vdev,
                                  unsigned int offset, const void *buf,
                                  unsigned len)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        struct ccw1 *ccw;
        void *config_area;
        unsigned long flags;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return;

        config_area = ccw_device_dma_zalloc(vcdev->cdev,
                                            VIRTIO_CCW_CONFIG_SIZE);
        if (!config_area)
                goto out_free;

        /* Make sure we don't overwrite fields. */
        if (vcdev->config_ready < offset)
                virtio_ccw_get_config(vdev, 0, NULL, offset);
        spin_lock_irqsave(&vcdev->lock, flags);
        memcpy(&vcdev->config[offset], buf, len);
        /* Write the config area to the host. */
        memcpy(config_area, vcdev->config, sizeof(vcdev->config));
        spin_unlock_irqrestore(&vcdev->lock, flags);
        ccw->cmd_code = CCW_CMD_WRITE_CONF;
        ccw->flags = 0;
        ccw->count = offset + len;
        ccw->cda = (__u32)(unsigned long)config_area;
        ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_CONFIG);

out_free:
        ccw_device_dma_free(vcdev->cdev, config_area, VIRTIO_CCW_CONFIG_SIZE);
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
}

static u8 virtio_ccw_get_status(struct virtio_device *vdev)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        u8 old_status = vcdev->dma_area->status;
        struct ccw1 *ccw;

        if (vcdev->revision < 2)
                return vcdev->dma_area->status;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return old_status;

        ccw->cmd_code = CCW_CMD_READ_STATUS;
        ccw->flags = 0;
        ccw->count = sizeof(vcdev->dma_area->status);
        ccw->cda = (__u32)(unsigned long)&vcdev->dma_area->status;
        ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_STATUS);
/*
 * If the channel program failed (should only happen if the device
 * was hotunplugged, and then we clean up via the machine check
 * handler anyway), vcdev->dma_area->status was not overwritten and we just
 * return the old status, which is fine.
*/
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));

        return vcdev->dma_area->status;
}

static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        u8 old_status = vcdev->dma_area->status;
        struct ccw1 *ccw;
        int ret;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return;

        /* Write the status to the host. */
        vcdev->dma_area->status = status;
        ccw->cmd_code = CCW_CMD_WRITE_STATUS;
        ccw->flags = 0;
        ccw->count = sizeof(status);
        ccw->cda = (__u32)(unsigned long)&vcdev->dma_area->status;
        /* We use ssch for setting the status which is a serializing
         * instruction that guarantees the memory writes have
         * completed before ssch.
         */
        ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_STATUS);
        /* Write failed? We assume status is unchanged. */
        if (ret)
                vcdev->dma_area->status = old_status;
        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
}

static const char *virtio_ccw_bus_name(struct virtio_device *vdev)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);

        return dev_name(&vcdev->cdev->dev);
}

static void virtio_ccw_synchronize_cbs(struct virtio_device *vdev)
{
        struct virtio_ccw_device *vcdev = to_vc_device(vdev);
        struct airq_info *info = vcdev->airq_info;

        if (info) {
                /*
                 * This device uses adapter interrupts: synchronize with
                 * vring_interrupt() called by virtio_airq_handler()

                 * via the indicator area lock.
                 */
                write_lock_irq(&info->lock);
                write_unlock_irq(&info->lock);
        } else {
                /* This device uses classic interrupts: synchronize
                 * with vring_interrupt() called by
                 * virtio_ccw_int_handler() via the per-device
                 * irq_lock
                 */
                write_lock_irq(&vcdev->irq_lock);
                write_unlock_irq(&vcdev->irq_lock);
        }
}

static const struct virtio_config_ops virtio_ccw_config_ops = {
        .get_features = virtio_ccw_get_features,
        .finalize_features = virtio_ccw_finalize_features,
        .get = virtio_ccw_get_config,
        .set = virtio_ccw_set_config,
        .get_status = virtio_ccw_get_status,
        .set_status = virtio_ccw_set_status,
        .reset = virtio_ccw_reset,
        .find_vqs = virtio_ccw_find_vqs,
        .del_vqs = virtio_ccw_del_vqs,
        .bus_name = virtio_ccw_bus_name,
        .synchronize_cbs = virtio_ccw_synchronize_cbs,
};


/*
 * ccw bus driver related functions
 */

static void virtio_ccw_release_dev(struct device *_d)
{
        struct virtio_device *dev = dev_to_virtio(_d);
        struct virtio_ccw_device *vcdev = to_vc_device(dev);

        ccw_device_dma_free(vcdev->cdev, vcdev->dma_area,
                            sizeof(*vcdev->dma_area));
        kfree(vcdev);
}

static int irb_is_error(struct irb *irb)
{
        if (scsw_cstat(&irb->scsw) != 0)
                return 1;
        if (scsw_dstat(&irb->scsw) & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
                return 1;
        if (scsw_cc(&irb->scsw) != 0)
                return 1;
        return 0;
}

static struct virtqueue *virtio_ccw_vq_by_ind(struct virtio_ccw_device *vcdev,
                                              int index)
{
        struct virtio_ccw_vq_info *info;
        unsigned long flags;
        struct virtqueue *vq;

        vq = NULL;
        spin_lock_irqsave(&vcdev->lock, flags);
        list_for_each_entry(info, &vcdev->virtqueues, node) {
                if (info->vq->index == index) {
                        vq = info->vq;
                        break;
                }
        }
        spin_unlock_irqrestore(&vcdev->lock, flags);
        return vq;
}

static void virtio_ccw_check_activity(struct virtio_ccw_device *vcdev,
                                      __u32 activity)
{
        if (vcdev->curr_io & activity) {
                switch (activity) {
                case VIRTIO_CCW_DOING_READ_FEAT:
                case VIRTIO_CCW_DOING_WRITE_FEAT:
                case VIRTIO_CCW_DOING_READ_CONFIG:
                case VIRTIO_CCW_DOING_WRITE_CONFIG:
                case VIRTIO_CCW_DOING_WRITE_STATUS:
                case VIRTIO_CCW_DOING_READ_STATUS:
                case VIRTIO_CCW_DOING_SET_VQ:
                case VIRTIO_CCW_DOING_SET_IND:
                case VIRTIO_CCW_DOING_SET_CONF_IND:
                case VIRTIO_CCW_DOING_RESET:
                case VIRTIO_CCW_DOING_READ_VQ_CONF:
                case VIRTIO_CCW_DOING_SET_IND_ADAPTER:
                case VIRTIO_CCW_DOING_SET_VIRTIO_REV:
                        vcdev->curr_io &= ~activity;
                        wake_up(&vcdev->wait_q);
                        break;
                default:
                        /* don't know what to do... */
                        dev_warn(&vcdev->cdev->dev,
                                 "Suspicious activity '%08x'\n", activity);
                        WARN_ON(1);
                        break;
                }
        }
}

static void virtio_ccw_int_handler(struct ccw_device *cdev,
                                   unsigned long intparm,
                                   struct irb *irb)
{
        __u32 activity = intparm & VIRTIO_CCW_INTPARM_MASK;
        struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
        int i;
        struct virtqueue *vq;

        if (!vcdev)
                return;
        if (IS_ERR(irb)) {
                vcdev->err = PTR_ERR(irb);
                virtio_ccw_check_activity(vcdev, activity);
                /* Don't poke around indicators, something's wrong. */
                return;
        }
        /* Check if it's a notification from the host. */
        if ((intparm == 0) &&
            (scsw_stctl(&irb->scsw) ==
             (SCSW_STCTL_ALERT_STATUS | SCSW_STCTL_STATUS_PEND))) {
                /* OK */
        }
        if (irb_is_error(irb)) {
                /* Command reject? */
                if ((scsw_dstat(&irb->scsw) & DEV_STAT_UNIT_CHECK) &&
                    (irb->ecw[0] & SNS0_CMD_REJECT))
                        vcdev->err = -EOPNOTSUPP;
                else
                        /* Map everything else to -EIO. */
                        vcdev->err = -EIO;
        }
        virtio_ccw_check_activity(vcdev, activity);
#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
        /*
         * Paired with virtio_ccw_synchronize_cbs() and interrupts are
         * disabled here.
         */
        read_lock(&vcdev->irq_lock);
#endif
        for_each_set_bit(i, indicators(vcdev),
                         sizeof(*indicators(vcdev)) * BITS_PER_BYTE) {
                /* The bit clear must happen before the vring kick. */
                clear_bit(i, indicators(vcdev));
                barrier();
                vq = virtio_ccw_vq_by_ind(vcdev, i);
                vring_interrupt(0, vq);
        }
#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
        read_unlock(&vcdev->irq_lock);
#endif
        if (test_bit(0, indicators2(vcdev))) {
                virtio_config_changed(&vcdev->vdev);
                clear_bit(0, indicators2(vcdev));
        }
}

/*
 * We usually want to autoonline all devices, but give the admin
 * a way to exempt devices from this.
 */
#define __DEV_WORDS ((__MAX_SUBCHANNEL + (8*sizeof(long) - 1)) / \
                     (8*sizeof(long)))
static unsigned long devs_no_auto[__MAX_SSID + 1][__DEV_WORDS];

static char *no_auto = "";

module_param(no_auto, charp, 0444);
MODULE_PARM_DESC(no_auto, "list of ccw bus id ranges not to be auto-onlined");

static int virtio_ccw_check_autoonline(struct ccw_device *cdev)
{
        struct ccw_dev_id id;

        ccw_device_get_id(cdev, &id);
        if (test_bit(id.devno, devs_no_auto[id.ssid]))
                return 0;
        return 1;
}

static void virtio_ccw_auto_online(void *data, async_cookie_t cookie)
{
        struct ccw_device *cdev = data;
        int ret;

        ret = ccw_device_set_online(cdev);
        if (ret)
                dev_warn(&cdev->dev, "Failed to set online: %d\n", ret);
}

static int virtio_ccw_probe(struct ccw_device *cdev)
{
        cdev->handler = virtio_ccw_int_handler;

        if (virtio_ccw_check_autoonline(cdev))
                async_schedule(virtio_ccw_auto_online, cdev);
        return 0;
}

static struct virtio_ccw_device *virtio_grab_drvdata(struct ccw_device *cdev)
{
        unsigned long flags;
        struct virtio_ccw_device *vcdev;

        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        vcdev = dev_get_drvdata(&cdev->dev);
        if (!vcdev || vcdev->going_away) {
                spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
                return NULL;
        }
        vcdev->going_away = true;
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        return vcdev;
}

static void virtio_ccw_remove(struct ccw_device *cdev)
{
        unsigned long flags;
        struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);

        if (vcdev && cdev->online) {
                if (vcdev->device_lost)
                        virtio_break_device(&vcdev->vdev);
                unregister_virtio_device(&vcdev->vdev);
                spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
                dev_set_drvdata(&cdev->dev, NULL);
                spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        }
        cdev->handler = NULL;
}

static int virtio_ccw_offline(struct ccw_device *cdev)
{
        unsigned long flags;
        struct virtio_ccw_device *vcdev = virtio_grab_drvdata(cdev);

        if (!vcdev)
                return 0;
        if (vcdev->device_lost)
                virtio_break_device(&vcdev->vdev);
        unregister_virtio_device(&vcdev->vdev);
        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        dev_set_drvdata(&cdev->dev, NULL);
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        return 0;
}

static int virtio_ccw_set_transport_rev(struct virtio_ccw_device *vcdev)
{
        struct virtio_rev_info *rev;
        struct ccw1 *ccw;
        int ret;

        ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
        if (!ccw)
                return -ENOMEM;
        rev = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*rev));
        if (!rev) {
                ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
                return -ENOMEM;
        }

        /* Set transport revision */
        ccw->cmd_code = CCW_CMD_SET_VIRTIO_REV;
        ccw->flags = 0;
        ccw->count = sizeof(*rev);
        ccw->cda = (__u32)(unsigned long)rev;

        vcdev->revision = VIRTIO_CCW_REV_MAX;
        do {
                rev->revision = vcdev->revision;
                /* none of our supported revisions carry payload */
                rev->length = 0;
                ret = ccw_io_helper(vcdev, ccw,
                                    VIRTIO_CCW_DOING_SET_VIRTIO_REV);
                if (ret == -EOPNOTSUPP) {
                        if (vcdev->revision == 0)
                                /*
                                 * The host device does not support setting
                                 * the revision: let's operate it in legacy
                                 * mode.
                                 */
                                ret = 0;
                        else
                                vcdev->revision--;
                }
        } while (ret == -EOPNOTSUPP);

        ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
        ccw_device_dma_free(vcdev->cdev, rev, sizeof(*rev));
        return ret;
}

static int virtio_ccw_online(struct ccw_device *cdev)
{
        int ret;
        struct virtio_ccw_device *vcdev;
        unsigned long flags;

        vcdev = kzalloc(sizeof(*vcdev), GFP_KERNEL);
        if (!vcdev) {
                dev_warn(&cdev->dev, "Could not get memory for virtio\n");
                ret = -ENOMEM;
                goto out_free;
        }
        vcdev->vdev.dev.parent = &cdev->dev;
        vcdev->cdev = cdev;
        vcdev->dma_area = ccw_device_dma_zalloc(vcdev->cdev,
                                                sizeof(*vcdev->dma_area));
        if (!vcdev->dma_area) {
                ret = -ENOMEM;
                goto out_free;
        }

        vcdev->is_thinint = virtio_ccw_use_airq; /* at least try */

        vcdev->vdev.dev.release = virtio_ccw_release_dev;
        vcdev->vdev.config = &virtio_ccw_config_ops;
        init_waitqueue_head(&vcdev->wait_q);
        INIT_LIST_HEAD(&vcdev->virtqueues);
        spin_lock_init(&vcdev->lock);
        rwlock_init(&vcdev->irq_lock);
        mutex_init(&vcdev->io_lock);

        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        dev_set_drvdata(&cdev->dev, vcdev);
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        vcdev->vdev.id.vendor = cdev->id.cu_type;
        vcdev->vdev.id.device = cdev->id.cu_model;

        ret = virtio_ccw_set_transport_rev(vcdev);
        if (ret)
                goto out_free;

        ret = register_virtio_device(&vcdev->vdev);
        if (ret) {
                dev_warn(&cdev->dev, "Failed to register virtio device: %d\n",
                         ret);
                goto out_put;
        }
        return 0;
out_put:
        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
        dev_set_drvdata(&cdev->dev, NULL);
        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
        put_device(&vcdev->vdev.dev);
        return ret;
out_free:
        if (vcdev) {
                ccw_device_dma_free(vcdev->cdev, vcdev->dma_area,
                                    sizeof(*vcdev->dma_area));
        }
        kfree(vcdev);
        return ret;
}

static int virtio_ccw_cio_notify(struct ccw_device *cdev, int event)
{
        int rc;
        struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);

        /*
         * Make sure vcdev is set
         * i.e. set_offline/remove callback not already running
         */
        if (!vcdev)
                return NOTIFY_DONE;

        switch (event) {
        case CIO_GONE:
                vcdev->device_lost = true;
                rc = NOTIFY_DONE;
                break;
        case CIO_OPER:
                rc = NOTIFY_OK;
                break;
        default:
                rc = NOTIFY_DONE;
                break;
        }
        return rc;
}

static struct ccw_device_id virtio_ids[] = {
        { CCW_DEVICE(0x3832, 0) },
        {},
};

static struct ccw_driver virtio_ccw_driver = {
        .driver = {
                .owner = THIS_MODULE,
                .name = "virtio_ccw",
        },
        .ids = virtio_ids,
        .probe = virtio_ccw_probe,
        .remove = virtio_ccw_remove,
        .set_offline = virtio_ccw_offline,
        .set_online = virtio_ccw_online,
        .notify = virtio_ccw_cio_notify,
        .int_class = IRQIO_VIR,
};

static int __init pure_hex(char **cp, unsigned int *val, int min_digit,
                           int max_digit, int max_val)
{
        int diff;

        diff = 0;
        *val = 0;

        while (diff <= max_digit) {
                int value = hex_to_bin(**cp);

                if (value < 0)
                        break;
                *val = *val * 16 + value;
                (*cp)++;
                diff++;
        }

        if ((diff < min_digit) || (diff > max_digit) || (*val > max_val))
                return 1;

        return 0;
}

static int __init parse_busid(char *str, unsigned int *cssid,
                              unsigned int *ssid, unsigned int *devno)
{
        char *str_work;
        int rc, ret;

        rc = 1;

        if (*str == '\0')
                goto out;

        str_work = str;
        ret = pure_hex(&str_work, cssid, 1, 2, __MAX_CSSID);
        if (ret || (str_work[0] != '.'))
                goto out;
        str_work++;
        ret = pure_hex(&str_work, ssid, 1, 1, __MAX_SSID);
        if (ret || (str_work[0] != '.'))
                goto out;
        str_work++;
        ret = pure_hex(&str_work, devno, 4, 4, __MAX_SUBCHANNEL);
        if (ret || (str_work[0] != '\0'))
                goto out;

        rc = 0;
out:
        return rc;
}

static void __init no_auto_parse(void)
{
        unsigned int from_cssid, to_cssid, from_ssid, to_ssid, from, to;
        char *parm, *str;
        int rc;

        str = no_auto;
        while ((parm = strsep(&str, ","))) {
                rc = parse_busid(strsep(&parm, "-"), &from_cssid,
                                 &from_ssid, &from);
                if (rc)
                        continue;
                if (parm != NULL) {
                        rc = parse_busid(parm, &to_cssid,
                                         &to_ssid, &to);
                        if ((from_ssid > to_ssid) ||
                            ((from_ssid == to_ssid) && (from > to)))
                                rc = -EINVAL;
                } else {
                        to_cssid = from_cssid;
                        to_ssid = from_ssid;
                        to = from;
                }
                if (rc)
                        continue;
                while ((from_ssid < to_ssid) ||
                       ((from_ssid == to_ssid) && (from <= to))) {
                        set_bit(from, devs_no_auto[from_ssid]);
                        from++;
                        if (from > __MAX_SUBCHANNEL) {
                                from_ssid++;
                                from = 0;
                        }
                }
        }
}

static int __init virtio_ccw_init(void)
{
        int rc;

        /* parse no_auto string before we do anything further */
        no_auto_parse();

        summary_indicators = cio_dma_zalloc(MAX_AIRQ_AREAS);
        if (!summary_indicators)
                return -ENOMEM;
        rc = ccw_driver_register(&virtio_ccw_driver);
        if (rc)
                cio_dma_free(summary_indicators, MAX_AIRQ_AREAS);
        return rc;
}
device_initcall(virtio_ccw_init);