// SPDX-License-Identifier: GPL-2.0
/*
 * Async I/O region for vfio_ccw
 *
 * Copyright Red Hat, Inc. 2019
 *
 * Author(s): Cornelia Huck <cohuck@redhat.com>
 */

#include <linux/vfio.h>

#include "vfio_ccw_private.h"

static ssize_t vfio_ccw_async_region_read(struct vfio_ccw_private *private,
                                          char __user *buf, size_t count,
                                          loff_t *ppos)
{
        unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
        loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
        struct ccw_cmd_region *region;
        int ret;

        if (pos + count > sizeof(*region))
                return -EINVAL;

        mutex_lock(&private->io_mutex);
        region = private->region[i].data;
        if (copy_to_user(buf, (void *)region + pos, count))
                ret = -EFAULT;
        else
                ret = count;
        mutex_unlock(&private->io_mutex);
        return ret;
}

static ssize_t vfio_ccw_async_region_write(struct vfio_ccw_private *private,
                                           const char __user *buf, size_t count,
                                           loff_t *ppos)
{
        unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
        loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
        struct ccw_cmd_region *region;
        int ret;

        if (pos + count > sizeof(*region))
                return -EINVAL;

        if (!mutex_trylock(&private->io_mutex))
                return -EAGAIN;

        region = private->region[i].data;
        if (copy_from_user((void *)region + pos, buf, count)) {
                ret = -EFAULT;
                goto out_unlock;
        }

        vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_ASYNC_REQ);

        ret = region->ret_code ? region->ret_code : count;

out_unlock:
        mutex_unlock(&private->io_mutex);
        return ret;
}

static void vfio_ccw_async_region_release(struct vfio_ccw_private *private,
                                          struct vfio_ccw_region *region)
{

}

static const struct vfio_ccw_regops vfio_ccw_async_region_ops = {
        .read = vfio_ccw_async_region_read,
        .write = vfio_ccw_async_region_write,
        .release = vfio_ccw_async_region_release,
};

int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private)
{
        return vfio_ccw_register_dev_region(private,
                                            VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD,
                                            &vfio_ccw_async_region_ops,
                                            sizeof(struct ccw_cmd_region),
                                            VFIO_REGION_INFO_FLAG_READ |
                                            VFIO_REGION_INFO_FLAG_WRITE,
                                            private->cmd_region);
}