/*
 * Intel Management Engine Interface (Intel MEI) Linux driver
 * Copyright (c) 2012-2013, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/interrupt.h>
#include <linux/mei_cl_bus.h>

#include "mei_dev.h"
#include "client.h"

#define to_mei_cl_driver(d) container_of(d, struct mei_cl_driver, driver)
#define to_mei_cl_device(d) container_of(d, struct mei_cl_device, dev)

/**
 * __mei_cl_send - internal client send (write)
 *
 * @cl: host client
 * @buf: buffer to send
 * @length: buffer length
 * @blocking: wait for write completion
 *
 * Return: written size bytes or < 0 on error
 */
ssize_t __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length,
			bool blocking)
{
	struct mei_device *bus;
	struct mei_cl_cb *cb = NULL;
	ssize_t rets;

	if (WARN_ON(!cl || !cl->dev))
		return -ENODEV;

	bus = cl->dev;

	mutex_lock(&bus->device_lock);
	if (!mei_cl_is_connected(cl)) {
		rets = -ENODEV;
		goto out;
	}

	/* Check if we have an ME client device */
	if (!mei_me_cl_is_active(cl->me_cl)) {
		rets = -ENOTTY;
		goto out;
	}

	if (length > mei_cl_mtu(cl)) {
		rets = -EFBIG;
		goto out;
	}

	cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, NULL);
	if (!cb) {
		rets = -ENOMEM;
		goto out;
	}

	memcpy(cb->buf.data, buf, length);

	rets = mei_cl_write(cl, cb, blocking);

out:
	mutex_unlock(&bus->device_lock);
	if (rets < 0)
		mei_io_cb_free(cb);

	return rets;
}

/**
 * __mei_cl_recv - internal client receive (read)
 *
 * @cl: host client
 * @buf: buffer to send
 * @length: buffer length
 *
 * Return: read size in bytes of < 0 on error
 */
ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length)
{
	struct mei_device *bus;
	struct mei_cl_cb *cb;
	size_t r_length;
	ssize_t rets;

	if (WARN_ON(!cl || !cl->dev))
		return -ENODEV;

	bus = cl->dev;

	mutex_lock(&bus->device_lock);

	cb = mei_cl_read_cb(cl, NULL);
	if (cb)
		goto copy;

	rets = mei_cl_read_start(cl, length, NULL);
	if (rets && rets != -EBUSY)
		goto out;

	/* wait on event only if there is no other waiter */
	if (list_empty(&cl->rd_completed) && !waitqueue_active(&cl->rx_wait)) {

		mutex_unlock(&bus->device_lock);

		if (wait_event_interruptible(cl->rx_wait,
				(!list_empty(&cl->rd_completed)) ||
				(!mei_cl_is_connected(cl)))) {

			if (signal_pending(current))
				return -EINTR;
			return -ERESTARTSYS;
		}

		mutex_lock(&bus->device_lock);

		if (!mei_cl_is_connected(cl)) {
			rets = -EBUSY;
			goto out;
		}
	}

	cb = mei_cl_read_cb(cl, NULL);
	if (!cb) {
		rets = 0;
		goto out;
	}

copy:
	if (cb->status) {
		rets = cb->status;
		goto free;
	}

	r_length = min_t(size_t, length, cb->buf_idx);
	memcpy(buf, cb->buf.data, r_length);
	rets = r_length;

free:
	mei_io_cb_free(cb);
out:
	mutex_unlock(&bus->device_lock);

	return rets;
}

/**
 * mei_cl_send - me device send  (write)
 *
 * @cldev: me client device
 * @buf: buffer to send
 * @length: buffer length
 *
 * Return: written size in bytes or < 0 on error
 */
ssize_t mei_cl_send(struct mei_cl_device *cldev, u8 *buf, size_t length)
{
	struct mei_cl *cl = cldev->cl;

	if (cl == NULL)
		return -ENODEV;

	return __mei_cl_send(cl, buf, length, 1);
}
EXPORT_SYMBOL_GPL(mei_cl_send);

/**
 * mei_cl_recv - client receive (read)
 *
 * @cldev: me client device
 * @buf: buffer to send
 * @length: buffer length
 *
 * Return: read size in bytes of < 0 on error
 */
ssize_t mei_cl_recv(struct mei_cl_device *cldev, u8 *buf, size_t length)
{
	struct mei_cl *cl = cldev->cl;

	if (cl == NULL)
		return -ENODEV;

	return __mei_cl_recv(cl, buf, length);
}
EXPORT_SYMBOL_GPL(mei_cl_recv);

/**
 * mei_bus_event_work  - dispatch rx event for a bus device
 *    and schedule new work
 *
 * @work: work
 */
static void mei_bus_event_work(struct work_struct *work)
{
	struct mei_cl_device *cldev;

	cldev = container_of(work, struct mei_cl_device, event_work);

	if (cldev->event_cb)
		cldev->event_cb(cldev, cldev->events, cldev->event_context);

	cldev->events = 0;

	/* Prepare for the next read */
	if (cldev->events_mask & BIT(MEI_CL_EVENT_RX))
		mei_cl_read_start(cldev->cl, 0, NULL);
}

/**
 * mei_cl_bus_notify_event - schedule notify cb on bus client
 *
 * @cl: host client
 */
void mei_cl_bus_notify_event(struct mei_cl *cl)
{
	struct mei_cl_device *cldev = cl->cldev;

	if (!cldev || !cldev->event_cb)
		return;

	if (!(cldev->events_mask & BIT(MEI_CL_EVENT_NOTIF)))
		return;

	if (!cl->notify_ev)
		return;

	set_bit(MEI_CL_EVENT_NOTIF, &cldev->events);

	schedule_work(&cldev->event_work);

	cl->notify_ev = false;
}

/**
 * mei_cl_bus_rx_event  - schedule rx evenet
 *
 * @cl: host client
 */
void mei_cl_bus_rx_event(struct mei_cl *cl)
{
	struct mei_cl_device *cldev = cl->cldev;

	if (!cldev || !cldev->event_cb)
		return;

	if (!(cldev->events_mask & BIT(MEI_CL_EVENT_RX)))
		return;

	set_bit(MEI_CL_EVENT_RX, &cldev->events);

	schedule_work(&cldev->event_work);
}

/**
 * mei_cl_register_event_cb - register event callback
 *
 * @cldev: me client devices
 * @event_cb: callback function
 * @events_mask: requested events bitmask
 * @context: driver context data
 *
 * Return: 0 on success
 *         -EALREADY if an callback is already registered
 *         <0 on other errors
 */
int mei_cl_register_event_cb(struct mei_cl_device *cldev,
			  unsigned long events_mask,
			  mei_cl_event_cb_t event_cb, void *context)
{
	int ret;

	if (cldev->event_cb)
		return -EALREADY;

	cldev->events = 0;
	cldev->events_mask = events_mask;
	cldev->event_cb = event_cb;
	cldev->event_context = context;
	INIT_WORK(&cldev->event_work, mei_bus_event_work);

	if (cldev->events_mask & BIT(MEI_CL_EVENT_RX)) {
		ret = mei_cl_read_start(cldev->cl, 0, NULL);
		if (ret && ret != -EBUSY)
			return ret;
	}

	if (cldev->events_mask & BIT(MEI_CL_EVENT_NOTIF)) {
		mutex_lock(&cldev->cl->dev->device_lock);
		ret = mei_cl_notify_request(cldev->cl, NULL, event_cb ? 1 : 0);
		mutex_unlock(&cldev->cl->dev->device_lock);
		if (ret)
			return ret;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(mei_cl_register_event_cb);

/**
 * mei_cl_get_drvdata - driver data getter
 *
 * @cldev: mei client device
 *
 * Return: driver private data
 */
void *mei_cl_get_drvdata(const struct mei_cl_device *cldev)
{
	return dev_get_drvdata(&cldev->dev);
}
EXPORT_SYMBOL_GPL(mei_cl_get_drvdata);

/**
 * mei_cl_set_drvdata - driver data setter
 *
 * @cldev: mei client device
 * @data: data to store
 */
void mei_cl_set_drvdata(struct mei_cl_device *cldev, void *data)
{
	dev_set_drvdata(&cldev->dev, data);
}
EXPORT_SYMBOL_GPL(mei_cl_set_drvdata);

/**
 * mei_cl_enable_device - enable me client device
 *     create connection with me client
 *
 * @cldev: me client device
 *
 * Return: 0 on success and < 0 on error
 */
int mei_cl_enable_device(struct mei_cl_device *cldev)
{
	struct mei_device *bus = cldev->bus;
	struct mei_cl *cl;
	int ret;

	cl = cldev->cl;

	if (!cl) {
		mutex_lock(&bus->device_lock);
		cl = mei_cl_alloc_linked(bus, MEI_HOST_CLIENT_ID_ANY);
		mutex_unlock(&bus->device_lock);
		if (IS_ERR(cl))
			return PTR_ERR(cl);
		/* update pointers */
		cldev->cl = cl;
		cl->cldev = cldev;
	}

	mutex_lock(&bus->device_lock);
	if (mei_cl_is_connected(cl)) {
		ret = 0;
		goto out;
	}

	if (!mei_me_cl_is_active(cldev->me_cl)) {
		dev_err(&cldev->dev, "me client is not active\n");
		ret = -ENOTTY;
		goto out;
	}

	ret = mei_cl_connect(cl, cldev->me_cl, NULL);
	if (ret < 0)
		dev_err(&cldev->dev, "cannot connect\n");

out:
	mutex_unlock(&bus->device_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(mei_cl_enable_device);

/**
 * mei_cl_disable_device - disable me client device
 *     disconnect form the me client
 *
 * @cldev: me client device
 *
 * Return: 0 on success and < 0 on error
 */
int mei_cl_disable_device(struct mei_cl_device *cldev)
{
	struct mei_device *bus;
	struct mei_cl *cl;
	int err;

	if (!cldev || !cldev->cl)
		return -ENODEV;

	cl = cldev->cl;

	bus = cldev->bus;

	cldev->event_cb = NULL;

	mutex_lock(&bus->device_lock);

	if (!mei_cl_is_connected(cl)) {
		dev_err(bus->dev, "Already disconnected");
		err = 0;
		goto out;
	}

	err = mei_cl_disconnect(cl);
	if (err < 0)
		dev_err(bus->dev, "Could not disconnect from the ME client");

out:
	/* Flush queues and remove any pending read */
	mei_cl_flush_queues(cl, NULL);
	mei_cl_unlink(cl);

	kfree(cl);
	cldev->cl = NULL;

	mutex_unlock(&bus->device_lock);
	return err;
}
EXPORT_SYMBOL_GPL(mei_cl_disable_device);

/**
 * mei_cl_device_find - find matching entry in the driver id table
 *
 * @cldev: me client device
 * @cldrv: me client driver
 *
 * Return: id on success; NULL if no id is matching
 */
static const
struct mei_cl_device_id *mei_cl_device_find(struct mei_cl_device *cldev,
					    struct mei_cl_driver *cldrv)
{
	const struct mei_cl_device_id *id;
	const uuid_le *uuid;

	uuid = mei_me_cl_uuid(cldev->me_cl);

	id = cldrv->id_table;
	while (uuid_le_cmp(NULL_UUID_LE, id->uuid)) {
		if (!uuid_le_cmp(*uuid, id->uuid)) {

			if (!cldev->name[0])
				return id;

			if (!strncmp(cldev->name, id->name, sizeof(id->name)))
				return id;
		}

		id++;
	}

	return NULL;
}

/**
 * mei_cl_device_match  - device match function
 *
 * @dev: device
 * @drv: driver
 *
 * Return:  1 if matching device was found 0 otherwise
 */
static int mei_cl_device_match(struct device *dev, struct device_driver *drv)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);
	struct mei_cl_driver *cldrv = to_mei_cl_driver(drv);
	const struct mei_cl_device_id *found_id;

	if (!cldev)
		return 0;

	if (!cldev->do_match)
		return 0;

	if (!cldrv || !cldrv->id_table)
		return 0;

	found_id = mei_cl_device_find(cldev, cldrv);
	if (found_id)
		return 1;

	return 0;
}

/**
 * mei_cl_device_probe - bus probe function
 *
 * @dev: device
 *
 * Return:  0 on success; < 0 otherwise
 */
static int mei_cl_device_probe(struct device *dev)
{
	struct mei_cl_device *cldev;
	struct mei_cl_driver *cldrv;
	const struct mei_cl_device_id *id;

	cldev = to_mei_cl_device(dev);
	cldrv = to_mei_cl_driver(dev->driver);

	if (!cldev)
		return 0;

	if (!cldrv || !cldrv->probe)
		return -ENODEV;

	id = mei_cl_device_find(cldev, cldrv);
	if (!id)
		return -ENODEV;

	__module_get(THIS_MODULE);

	return cldrv->probe(cldev, id);
}

/**
 * mei_cl_device_remove - remove device from the bus
 *
 * @dev: device
 *
 * Return:  0 on success; < 0 otherwise
 */
static int mei_cl_device_remove(struct device *dev)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);
	struct mei_cl_driver *cldrv;
	int ret = 0;

	if (!cldev || !dev->driver)
		return 0;

	if (cldev->event_cb) {
		cldev->event_cb = NULL;
		cancel_work_sync(&cldev->event_work);
	}

	cldrv = to_mei_cl_driver(dev->driver);
	if (cldrv->remove)
		ret = cldrv->remove(cldev);

	module_put(THIS_MODULE);
	dev->driver = NULL;
	return ret;

}

static ssize_t name_show(struct device *dev, struct device_attribute *a,
			     char *buf)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);
	size_t len;

	len = snprintf(buf, PAGE_SIZE, "%s", cldev->name);

	return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
}
static DEVICE_ATTR_RO(name);

static ssize_t uuid_show(struct device *dev, struct device_attribute *a,
			     char *buf)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);
	const uuid_le *uuid = mei_me_cl_uuid(cldev->me_cl);
	size_t len;

	len = snprintf(buf, PAGE_SIZE, "%pUl", uuid);

	return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
}
static DEVICE_ATTR_RO(uuid);

static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
			     char *buf)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);
	const uuid_le *uuid = mei_me_cl_uuid(cldev->me_cl);
	size_t len;

	len = snprintf(buf, PAGE_SIZE, "mei:%s:" MEI_CL_UUID_FMT ":",
		cldev->name, MEI_CL_UUID_ARGS(uuid->b));

	return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *mei_cl_dev_attrs[] = {
	&dev_attr_name.attr,
	&dev_attr_uuid.attr,
	&dev_attr_modalias.attr,
	NULL,
};
ATTRIBUTE_GROUPS(mei_cl_dev);

/**
 * mei_cl_device_uevent - me client bus uevent handler
 *
 * @dev: device
 * @env: uevent kobject
 *
 * Return: 0 on success -ENOMEM on when add_uevent_var fails
 */
static int mei_cl_device_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);
	const uuid_le *uuid = mei_me_cl_uuid(cldev->me_cl);

	if (add_uevent_var(env, "MEI_CL_UUID=%pUl", uuid))
		return -ENOMEM;

	if (add_uevent_var(env, "MEI_CL_NAME=%s", cldev->name))
		return -ENOMEM;

	if (add_uevent_var(env, "MODALIAS=mei:%s:" MEI_CL_UUID_FMT ":",
		cldev->name, MEI_CL_UUID_ARGS(uuid->b)))
		return -ENOMEM;

	return 0;
}

static struct bus_type mei_cl_bus_type = {
	.name		= "mei",
	.dev_groups	= mei_cl_dev_groups,
	.match		= mei_cl_device_match,
	.probe		= mei_cl_device_probe,
	.remove		= mei_cl_device_remove,
	.uevent		= mei_cl_device_uevent,
};

static struct mei_device *mei_dev_bus_get(struct mei_device *bus)
{
	if (bus)
		get_device(bus->dev);

	return bus;
}

static void mei_dev_bus_put(struct mei_device *bus)
{
	if (bus)
		put_device(bus->dev);
}

static void mei_cl_dev_release(struct device *dev)
{
	struct mei_cl_device *cldev = to_mei_cl_device(dev);

	if (!cldev)
		return;

	mei_me_cl_put(cldev->me_cl);
	mei_dev_bus_put(cldev->bus);
	kfree(cldev);
}

static struct device_type mei_cl_device_type = {
	.release	= mei_cl_dev_release,
};

/**
 * mei_cl_dev_alloc - initialize and allocate mei client device
 *
 * @bus: mei device
 * @me_cl: me client
 *
 * Return: allocated device structur or NULL on allocation failure
 */
static struct mei_cl_device *mei_cl_dev_alloc(struct mei_device *bus,
					      struct mei_me_client *me_cl)
{
	struct mei_cl_device *cldev;

	cldev = kzalloc(sizeof(struct mei_cl_device), GFP_KERNEL);
	if (!cldev)
		return NULL;

	device_initialize(&cldev->dev);
	cldev->dev.parent = bus->dev;
	cldev->dev.bus    = &mei_cl_bus_type;
	cldev->dev.type   = &mei_cl_device_type;
	cldev->bus        = mei_dev_bus_get(bus);
	cldev->me_cl      = mei_me_cl_get(me_cl);
	cldev->is_added   = 0;
	INIT_LIST_HEAD(&cldev->bus_list);

	return cldev;
}

/**
 * mei_cl_dev_setup - setup me client device
 *    run fix up routines and set the device name
 *
 * @bus: mei device
 * @cldev: me client device
 *
 * Return: true if the device is eligible for enumeration
 */
static bool mei_cl_dev_setup(struct mei_device *bus,
			     struct mei_cl_device *cldev)
{
	cldev->do_match = 1;
	mei_cl_dev_fixup(cldev);

	if (cldev->do_match)
		dev_set_name(&cldev->dev, "mei:%s:%pUl",
			     cldev->name, mei_me_cl_uuid(cldev->me_cl));

	return cldev->do_match == 1;
}

/**
 * mei_cl_bus_dev_add - add me client devices
 *
 * @cldev: me client device
 *
 * Return: 0 on success; < 0 on failre
 */
static int mei_cl_bus_dev_add(struct mei_cl_device *cldev)
{
	int ret;

	dev_dbg(cldev->bus->dev, "adding %pUL\n", mei_me_cl_uuid(cldev->me_cl));
	ret = device_add(&cldev->dev);
	if (!ret)
		cldev->is_added = 1;

	return ret;
}

/**
 * mei_cl_bus_dev_stop - stop the driver
 *
 * @cldev: me client device
 */
static void mei_cl_bus_dev_stop(struct mei_cl_device *cldev)
{
	if (cldev->is_added)
		device_release_driver(&cldev->dev);
}

/**
 * mei_cl_bus_dev_destroy - destroy me client devices object
 *
 * @cldev: me client device
 */
static void mei_cl_bus_dev_destroy(struct mei_cl_device *cldev)
{
	if (!cldev->is_added)
		return;

	device_del(&cldev->dev);

	mutex_lock(&cldev->bus->cl_bus_lock);
	list_del_init(&cldev->bus_list);
	mutex_unlock(&cldev->bus->cl_bus_lock);

	cldev->is_added = 0;
	put_device(&cldev->dev);
}

/**
 * mei_cl_bus_remove_device - remove a devices form the bus
 *
 * @cldev: me client device
 */
static void mei_cl_bus_remove_device(struct mei_cl_device *cldev)
{
	mei_cl_bus_dev_stop(cldev);
	mei_cl_bus_dev_destroy(cldev);
}

/**
 * mei_cl_bus_remove_devices - remove all devices form the bus
 *
 * @bus: mei device
 */
void mei_cl_bus_remove_devices(struct mei_device *bus)
{
	struct mei_cl_device *cldev, *next;

	list_for_each_entry_safe(cldev, next, &bus->device_list, bus_list)
		mei_cl_bus_remove_device(cldev);
}


/**
 * mei_cl_dev_init - allocate and initializes an mei client devices
 *     based on me client
 *
 * @bus: mei device
 * @me_cl: me client
 */
static void mei_cl_dev_init(struct mei_device *bus, struct mei_me_client *me_cl)
{
	struct mei_cl_device *cldev;

	dev_dbg(bus->dev, "initializing %pUl", mei_me_cl_uuid(me_cl));

	if (me_cl->bus_added)
		return;

	cldev = mei_cl_dev_alloc(bus, me_cl);
	if (!cldev)
		return;

	mutex_lock(&cldev->bus->cl_bus_lock);
	me_cl->bus_added = true;
	list_add_tail(&cldev->bus_list, &bus->device_list);
	mutex_unlock(&cldev->bus->cl_bus_lock);

}

/**
 * mei_cl_bus_rescan - scan me clients list and add create
 *    devices for eligible clients
 *
 * @bus: mei device
 */
void mei_cl_bus_rescan(struct mei_device *bus)
{
	struct mei_cl_device *cldev, *n;
	struct mei_me_client *me_cl;

	down_read(&bus->me_clients_rwsem);
	list_for_each_entry(me_cl, &bus->me_clients, list)
		mei_cl_dev_init(bus, me_cl);
	up_read(&bus->me_clients_rwsem);

	mutex_lock(&bus->cl_bus_lock);
	list_for_each_entry_safe(cldev, n, &bus->device_list, bus_list) {

		if (!mei_me_cl_is_active(cldev->me_cl)) {
			mei_cl_bus_remove_device(cldev);
			continue;
		}

		if (cldev->is_added)
			continue;

		if (mei_cl_dev_setup(bus, cldev))
			mei_cl_bus_dev_add(cldev);
		else {
			list_del_init(&cldev->bus_list);
			put_device(&cldev->dev);
		}
	}
	mutex_unlock(&bus->cl_bus_lock);

	dev_dbg(bus->dev, "rescan end");
}

int __mei_cl_driver_register(struct mei_cl_driver *cldrv, struct module *owner)
{
	int err;

	cldrv->driver.name = cldrv->name;
	cldrv->driver.owner = owner;
	cldrv->driver.bus = &mei_cl_bus_type;

	err = driver_register(&cldrv->driver);
	if (err)
		return err;

	pr_debug("mei: driver [%s] registered\n", cldrv->driver.name);

	return 0;
}
EXPORT_SYMBOL_GPL(__mei_cl_driver_register);

void mei_cl_driver_unregister(struct mei_cl_driver *cldrv)
{
	driver_unregister(&cldrv->driver);

	pr_debug("mei: driver [%s] unregistered\n", cldrv->driver.name);
}
EXPORT_SYMBOL_GPL(mei_cl_driver_unregister);


int __init mei_cl_bus_init(void)
{
	return bus_register(&mei_cl_bus_type);
}

void __exit mei_cl_bus_exit(void)
{
	bus_unregister(&mei_cl_bus_type);
}