// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2021 Intel Corporation. All rights rsvd. */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/device/bus.h>
#include "idxd.h"

extern void device_driver_detach(struct device *dev);

#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
        struct driver_attribute driver_attr_##_name =           \
        __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)

static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count)
{
        const struct bus_type *bus = drv->bus;
        struct device *dev;
        int rc = -ENODEV;

        dev = bus_find_device_by_name(bus, NULL, buf);
        if (!dev)
                return -ENODEV;

        if (dev->driver) {
                device_driver_detach(dev);
                rc = count;
        }

        put_device(dev);

        return rc;
}
static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);

static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count)
{
        const struct bus_type *bus = drv->bus;
        struct device *dev;
        struct device_driver *alt_drv = NULL;
        int rc = -ENODEV;
        struct idxd_dev *idxd_dev;

        dev = bus_find_device_by_name(bus, NULL, buf);
        if (!dev)
                return -ENODEV;

        if (dev->driver || drv != &dsa_drv.drv)
                goto err_put_dev;

        idxd_dev = confdev_to_idxd_dev(dev);
        if (is_idxd_dev(idxd_dev)) {
                alt_drv = driver_find("idxd", bus);
        } else if (is_idxd_wq_dev(idxd_dev)) {
                struct idxd_wq *wq = confdev_to_wq(dev);

                if (is_idxd_wq_kernel(wq))
                        alt_drv = driver_find("dmaengine", bus);
                else if (is_idxd_wq_user(wq))
                        alt_drv = driver_find("user", bus);
        }
        if (!alt_drv)
                goto err_put_dev;

        rc = device_driver_attach(alt_drv, dev);
        if (rc < 0)
                goto err_put_dev;

        put_device(dev);

        return count;

err_put_dev:
        put_device(dev);

        return rc;
}
static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);

static struct attribute *dsa_drv_compat_attrs[] = {
        &driver_attr_bind.attr,
        &driver_attr_unbind.attr,
        NULL,
};

static const struct attribute_group dsa_drv_compat_attr_group = {
        .attrs = dsa_drv_compat_attrs,
};

static const struct attribute_group *dsa_drv_compat_groups[] = {
        &dsa_drv_compat_attr_group,
        NULL,
};

static int idxd_dsa_drv_probe(struct idxd_dev *idxd_dev)
{
        return -ENODEV;
}

static void idxd_dsa_drv_remove(struct idxd_dev *idxd_dev)
{
}

static enum idxd_dev_type dev_types[] = {
        IDXD_DEV_NONE,
};

struct idxd_device_driver dsa_drv = {
        .name = "dsa",
        .probe = idxd_dsa_drv_probe,
        .remove = idxd_dsa_drv_remove,
        .type = dev_types,
        .drv = {
                .suppress_bind_attrs = true,
                .groups = dsa_drv_compat_groups,
        },
};

module_idxd_driver(dsa_drv);
MODULE_IMPORT_NS("IDXD");