// SPDX-License-Identifier: GPL-2.0+
/*
 * VFIO based AP device driver
 *
 * Copyright IBM Corp. 2018
 *
 * Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
 *            Pierre Morel <pmorel@linux.ibm.com>
 */

#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <asm/facility.h>
#include "vfio_ap_private.h"

#define VFIO_AP_ROOT_NAME "vfio_ap"
#define VFIO_AP_DEV_NAME "matrix"

MODULE_AUTHOR("IBM Corporation");
MODULE_DESCRIPTION("VFIO AP device driver, Copyright IBM Corp. 2018");
MODULE_LICENSE("GPL v2");

static struct ap_driver vfio_ap_drv;

struct ap_matrix_dev *matrix_dev;

/* Only type 10 adapters (CEX4 and later) are supported
 * by the AP matrix device driver
 */
static struct ap_device_id ap_queue_ids[] = {
        { .dev_type = AP_DEVICE_TYPE_CEX4,
          .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
        { .dev_type = AP_DEVICE_TYPE_CEX5,
          .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
        { .dev_type = AP_DEVICE_TYPE_CEX6,
          .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
        { .dev_type = AP_DEVICE_TYPE_CEX7,
          .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
        { /* end of sibling */ },
};

MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);

/**
 * vfio_ap_queue_dev_probe:
 *
 * Allocate a vfio_ap_queue structure and associate it
 * with the device as driver_data.
 */
static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
{
        struct vfio_ap_queue *q;

        q = kzalloc(sizeof(*q), GFP_KERNEL);
        if (!q)
                return -ENOMEM;
        dev_set_drvdata(&apdev->device, q);
        q->apqn = to_ap_queue(&apdev->device)->qid;
        q->saved_isc = VFIO_AP_ISC_INVALID;
        return 0;
}

/**
 * vfio_ap_queue_dev_remove:
 *
 * Takes the matrix lock to avoid actions on this device while removing
 * Free the associated vfio_ap_queue structure
 */
static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
{
        struct vfio_ap_queue *q;

        mutex_lock(&matrix_dev->lock);
        q = dev_get_drvdata(&apdev->device);
        vfio_ap_mdev_reset_queue(q, 1);
        dev_set_drvdata(&apdev->device, NULL);
        kfree(q);
        mutex_unlock(&matrix_dev->lock);
}

static void vfio_ap_matrix_dev_release(struct device *dev)
{
        struct ap_matrix_dev *matrix_dev = dev_get_drvdata(dev);

        kfree(matrix_dev);
}

static int matrix_bus_match(struct device *dev, struct device_driver *drv)
{
        return 1;
}

static struct bus_type matrix_bus = {
        .name = "matrix",
        .match = &matrix_bus_match,
};

static struct device_driver matrix_driver = {
        .name = "vfio_ap",
        .bus = &matrix_bus,
        .suppress_bind_attrs = true,
};

static int vfio_ap_matrix_dev_create(void)
{
        int ret;
        struct device *root_device;

        root_device = root_device_register(VFIO_AP_ROOT_NAME);
        if (IS_ERR(root_device))
                return PTR_ERR(root_device);

        ret = bus_register(&matrix_bus);
        if (ret)
                goto bus_register_err;

        matrix_dev = kzalloc(sizeof(*matrix_dev), GFP_KERNEL);
        if (!matrix_dev) {
                ret = -ENOMEM;
                goto matrix_alloc_err;
        }

        /* Fill in config info via PQAP(QCI), if available */
        if (test_facility(12)) {
                ret = ap_qci(&matrix_dev->info);
                if (ret)
                        goto matrix_alloc_err;
        }

        mutex_init(&matrix_dev->lock);
        INIT_LIST_HEAD(&matrix_dev->mdev_list);

        dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
        matrix_dev->device.parent = root_device;
        matrix_dev->device.bus = &matrix_bus;
        matrix_dev->device.release = vfio_ap_matrix_dev_release;
        matrix_dev->vfio_ap_drv = &vfio_ap_drv;

        ret = device_register(&matrix_dev->device);
        if (ret)
                goto matrix_reg_err;

        ret = driver_register(&matrix_driver);
        if (ret)
                goto matrix_drv_err;

        return 0;

matrix_drv_err:
        device_unregister(&matrix_dev->device);
matrix_reg_err:
        put_device(&matrix_dev->device);
matrix_alloc_err:
        bus_unregister(&matrix_bus);
bus_register_err:
        root_device_unregister(root_device);
        return ret;
}

static void vfio_ap_matrix_dev_destroy(void)
{
        struct device *root_device = matrix_dev->device.parent;

        driver_unregister(&matrix_driver);
        device_unregister(&matrix_dev->device);
        bus_unregister(&matrix_bus);
        root_device_unregister(root_device);
}

static int __init vfio_ap_init(void)
{
        int ret;

        /* If there are no AP instructions, there is nothing to pass through. */
        if (!ap_instructions_available())
                return -ENODEV;

        ret = vfio_ap_matrix_dev_create();
        if (ret)
                return ret;

        memset(&vfio_ap_drv, 0, sizeof(vfio_ap_drv));
        vfio_ap_drv.probe = vfio_ap_queue_dev_probe;
        vfio_ap_drv.remove = vfio_ap_queue_dev_remove;
        vfio_ap_drv.ids = ap_queue_ids;

        ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
        if (ret) {
                vfio_ap_matrix_dev_destroy();
                return ret;
        }

        ret = vfio_ap_mdev_register();
        if (ret) {
                ap_driver_unregister(&vfio_ap_drv);
                vfio_ap_matrix_dev_destroy();

                return ret;
        }

        return 0;
}

static void __exit vfio_ap_exit(void)
{
        vfio_ap_mdev_unregister();
        ap_driver_unregister(&vfio_ap_drv);
        vfio_ap_matrix_dev_destroy();
}

module_init(vfio_ap_init);
module_exit(vfio_ap_exit);