// 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"
#include "vfio_ap_debug.h"

#define VFIO_AP_ROOT_NAME "vfio_ap"
#define VFIO_AP_DEV_NAME "matrix"
#define AP_QUEUE_ASSIGNED "assigned"
#define AP_QUEUE_UNASSIGNED "unassigned"
#define AP_QUEUE_IN_USE "in use"

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

struct ap_matrix_dev *matrix_dev;
debug_info_t *vfio_ap_dbf_info;

/* 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 },
	{ .dev_type = AP_DEVICE_TYPE_CEX8,
	  .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
	{ /* end of sibling */ },
};

static struct ap_matrix_mdev *vfio_ap_mdev_for_queue(struct vfio_ap_queue *q)
{
	struct ap_matrix_mdev *matrix_mdev;
	unsigned long apid = AP_QID_CARD(q->apqn);
	unsigned long apqi = AP_QID_QUEUE(q->apqn);

	list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
		if (test_bit_inv(apid, matrix_mdev->matrix.apm) &&
		    test_bit_inv(apqi, matrix_mdev->matrix.aqm))
			return matrix_mdev;
	}

	return NULL;
}

static ssize_t status_show(struct device *dev,
			   struct device_attribute *attr,
			   char *buf)
{
	ssize_t nchars = 0;
	struct vfio_ap_queue *q;
	struct ap_matrix_mdev *matrix_mdev;
	struct ap_device *apdev = to_ap_dev(dev);

	mutex_lock(&matrix_dev->lock);
	q = dev_get_drvdata(&apdev->device);
	matrix_mdev = vfio_ap_mdev_for_queue(q);

	if (matrix_mdev) {
		if (matrix_mdev->kvm)
			nchars = scnprintf(buf, PAGE_SIZE, "%s\n",
					   AP_QUEUE_IN_USE);
		else
			nchars = scnprintf(buf, PAGE_SIZE, "%s\n",
					   AP_QUEUE_ASSIGNED);
	} else {
		nchars = scnprintf(buf, PAGE_SIZE, "%s\n",
				   AP_QUEUE_UNASSIGNED);
	}

	mutex_unlock(&matrix_dev->lock);

	return nchars;
}

static DEVICE_ATTR_RO(status);

static struct attribute *vfio_queue_attrs[] = {
	&dev_attr_status.attr,
	NULL,
};

static const struct attribute_group vfio_queue_attr_group = {
	.attrs = vfio_queue_attrs,
};

/**
 * vfio_ap_queue_dev_probe: Allocate a vfio_ap_queue structure and associate it
 *			    with the device as driver_data.
 *
 * @apdev: the AP device being probed
 *
 * Return: returns 0 if the probe succeeded; otherwise, returns an error if
 *	   storage could not be allocated for a vfio_ap_queue object or the
 *	   sysfs 'status' attribute could not be created for the queue device.
 */
static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
{
	int ret;
	struct vfio_ap_queue *q;

	q = kzalloc(sizeof(*q), GFP_KERNEL);
	if (!q)
		return -ENOMEM;

	mutex_lock(&matrix_dev->lock);
	dev_set_drvdata(&apdev->device, q);
	q->apqn = to_ap_queue(&apdev->device)->qid;
	q->saved_isc = VFIO_AP_ISC_INVALID;

	ret = sysfs_create_group(&apdev->device.kobj, &vfio_queue_attr_group);
	if (ret) {
		dev_set_drvdata(&apdev->device, NULL);
		kfree(q);
	}

	mutex_unlock(&matrix_dev->lock);

	return ret;
}

/**
 * vfio_ap_queue_dev_remove: Free the associated vfio_ap_queue structure.
 *
 * @apdev: the AP device being removed
 *
 * Takes the matrix lock to avoid actions on this device while doing the remove.
 */
static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
{
	struct vfio_ap_queue *q;

	mutex_lock(&matrix_dev->lock);
	sysfs_remove_group(&apdev->device.kobj, &vfio_queue_attr_group);
	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 struct ap_driver vfio_ap_drv = {
	.probe = vfio_ap_queue_dev_probe,
	.remove = vfio_ap_queue_dev_remove,
	.ids = ap_queue_ids,
};

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_dbf_info_init(void)
{
	vfio_ap_dbf_info = debug_register("vfio_ap", 1, 1,
					  DBF_MAX_SPRINTF_ARGS * sizeof(long));

	if (!vfio_ap_dbf_info)
		return -ENOENT;

	debug_register_view(vfio_ap_dbf_info, &debug_sprintf_view);
	debug_set_level(vfio_ap_dbf_info, DBF_WARN);

	return 0;
}

static int __init vfio_ap_init(void)
{
	int ret;

	ret = vfio_ap_dbf_info_init();
	if (ret)
		return 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;

	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();
	debug_unregister(vfio_ap_dbf_info);
}

module_init(vfio_ap_init);
module_exit(vfio_ap_exit);