// SPDX-License-Identifier: GPL-2.0
/*
 * Channel path related status regions for vfio_ccw
 *
 * Copyright IBM Corp. 2020
 *
 * Author(s): Farhan Ali <alifm@linux.ibm.com>
 *            Eric Farman <farman@linux.ibm.com>
 */

#include <linux/slab.h>
#include <linux/vfio.h>
#include "vfio_ccw_private.h"

static ssize_t vfio_ccw_schib_region_read(struct vfio_ccw_private *private,
                                          char __user *buf, size_t count,
                                          loff_t *ppos)
{
        struct subchannel *sch = to_subchannel(private->vdev.dev->parent);
        unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
        loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
        struct ccw_schib_region *region;
        int ret;

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

        mutex_lock(&private->io_mutex);
        region = private->region[i].data;

        if (cio_update_schib(sch)) {
                ret = -ENODEV;
                goto out;
        }

        memcpy(region, &sch->schib, sizeof(*region));

        if (copy_to_user(buf, (void *)region + pos, count)) {
                ret = -EFAULT;
                goto out;
        }

        ret = count;

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

static ssize_t vfio_ccw_schib_region_write(struct vfio_ccw_private *private,
                                           const char __user *buf, size_t count,
                                           loff_t *ppos)
{
        return -EINVAL;
}


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

}

static const struct vfio_ccw_regops vfio_ccw_schib_region_ops = {
        .read = vfio_ccw_schib_region_read,
        .write = vfio_ccw_schib_region_write,
        .release = vfio_ccw_schib_region_release,
};

int vfio_ccw_register_schib_dev_regions(struct vfio_ccw_private *private)
{
        return vfio_ccw_register_dev_region(private,
                                            VFIO_REGION_SUBTYPE_CCW_SCHIB,
                                            &vfio_ccw_schib_region_ops,
                                            sizeof(struct ccw_schib_region),
                                            VFIO_REGION_INFO_FLAG_READ,
                                            private->schib_region);
}

static ssize_t vfio_ccw_crw_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_crw_region *region;
        struct vfio_ccw_crw *crw;
        int ret;

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

        crw = list_first_entry_or_null(&private->crw,
                                       struct vfio_ccw_crw, next);

        if (crw)
                list_del(&crw->next);

        mutex_lock(&private->io_mutex);
        region = private->region[i].data;

        if (crw)
                memcpy(&region->crw, &crw->crw, sizeof(region->crw));

        if (copy_to_user(buf, (void *)region + pos, count))
                ret = -EFAULT;
        else
                ret = count;

        region->crw = 0;

        mutex_unlock(&private->io_mutex);

        kfree(crw);

        /* Notify the guest if more CRWs are on our queue */
        if (!list_empty(&private->crw) && private->crw_trigger)
                eventfd_signal(private->crw_trigger);

        return ret;
}

static ssize_t vfio_ccw_crw_region_write(struct vfio_ccw_private *private,
                                         const char __user *buf, size_t count,
                                         loff_t *ppos)
{
        return -EINVAL;
}

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

}

static const struct vfio_ccw_regops vfio_ccw_crw_region_ops = {
        .read = vfio_ccw_crw_region_read,
        .write = vfio_ccw_crw_region_write,
        .release = vfio_ccw_crw_region_release,
};

int vfio_ccw_register_crw_dev_regions(struct vfio_ccw_private *private)
{
        return vfio_ccw_register_dev_region(private,
                                            VFIO_REGION_SUBTYPE_CCW_CRW,
                                            &vfio_ccw_crw_region_ops,
                                            sizeof(struct ccw_crw_region),
                                            VFIO_REGION_INFO_FLAG_READ,
                                            private->crw_region);
}