path: root/drivers/misc/mei/bus.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2012-2019, Intel Corporation. All rights reserved.
 * Intel Management Engine Interface (Intel MEI) Linux driver
 */

#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/sched/signal.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)

/**
 * __mei_cl_send - internal client send (write)
 *
 * @cl: host client
 * @buf: buffer to send
 * @length: buffer length
 * @mode: sending mode
 *
 * Return: written size bytes or < 0 on error
 */
ssize_t __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length,
		      unsigned int mode)
{
	struct mei_device *bus;
	struct mei_cl_cb *cb;
	ssize_t rets;

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

	bus = cl->dev;

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

	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;
	}

	while (cl->tx_cb_queued >= bus->tx_queue_limit) {
		mutex_unlock(&bus->device_lock);
		rets = wait_event_interruptible(cl->tx_wait,
				cl->writing_state == MEI_WRITE_COMPLETE ||
				(!mei_cl_is_connected(cl)));
		mutex_lock(&bus->device_lock);
		if (rets) {
			if (signal_pending(current))
				rets = -EINTR;
			goto out;
		}
		if (!mei_cl_is_connected(cl)) {
			rets = -ENODEV;
			goto out;
		}
	}

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

	cb->internal = !!(mode & MEI_CL_IO_TX_INTERNAL);
	cb->blocking = !!(mode & MEI_CL_IO_TX_BLOCKING);
	memcpy(cb->buf.data, buf, length);

	rets = mei_cl_write(cl, cb);

out:
	mutex_unlock(&bus->device_lock);

	return rets;
}

/**
 * __mei_cl_recv - internal client receive (read)
 *
 * @cl: host client
 * @buf: buffer to receive
 * @length: buffer length
 * @mode: io mode
 * @timeout: recv timeout, 0 for infinite timeout
 *
 * Return: read size in bytes of < 0 on error
 */
ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length,
		      unsigned int mode, unsigned long timeout)
{
	struct mei_device *bus;
	struct mei_cl_cb *cb;
	size_t r_length;
	ssize_t rets;
	bool nonblock = !!(mode & MEI_CL_IO_RX_NONBLOCK);

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

	bus = cl->dev;

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

	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;

	if (nonblock) {
		rets = -EAGAIN;
		goto out;
	}

	/* wait on event only if there is no other waiter */
	/* synchronized under device mutex */
	if (!waitqueue_active(&cl->rx_wait)) {

		mutex_unlock(&bus->device_lock);

		if (timeout) {
			rets = wait_event_interruptible_timeout
					(cl->rx_wait,
					(!list_empty(&cl->rd_completed)) ||
					(!mei_cl_is_connected(cl)),
					msecs_to_jiffies(timeout));
			if (rets == 0)
				return -ETIME;
			if (rets < 0) {
				if (signal_pending(current))
					return -EINTR;
				return -ERESTARTSYS;
			}
		} else