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

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2003-2018, Intel Corporation. All rights reserved.
 * Intel Management Engine Interface (Intel MEI) Linux driver
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/sched/signal.h>
#include <linux/uuid.h>
#include <linux/compat.h>
#include <linux/jiffies.h>
#include <linux/interrupt.h>

#include <linux/mei.h>

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

static struct class *mei_class;
static dev_t mei_devt;
#define MEI_MAX_DEVS  MINORMASK
static DEFINE_MUTEX(mei_minor_lock);
static DEFINE_IDR(mei_idr);

/**
 * mei_open - the open function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * Return: 0 on success, <0 on error
 */
static int mei_open(struct inode *inode, struct file *file)
{
	struct mei_device *dev;
	struct mei_cl *cl;

	int err;

	dev = container_of(inode->i_cdev, struct mei_device, cdev);
	if (!dev)
		return -ENODEV;

	mutex_lock(&dev->device_lock);

	if (dev->dev_state != MEI_DEV_ENABLED) {
		dev_dbg(dev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
		    mei_dev_state_str(dev->dev_state));
		err = -ENODEV;
		goto err_unlock;
	}

	cl = mei_cl_alloc_linked(dev);
	if (IS_ERR(cl)) {
		err = PTR_ERR(cl);
		goto err_unlock;
	}

	cl->fp = file;
	file->private_data = cl;

	mutex_unlock(&dev->device_lock);

	return nonseekable_open(inode, file);

err_unlock:
	mutex_unlock(&dev->device_lock);
	return err;
}

/**
 * mei_release - the release function
 *
 * @inode: pointer to inode structure
 * @file: pointer to file structure
 *
 * Return: 0 on success, <0 on error
 */
static int mei_release(struct inode *inode, struct file *file)
{
	struct mei_cl *cl = file->private_data;
	struct mei_device *dev;
	int rets;

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

	dev = cl->dev;

	mutex_lock(&dev->device_lock);

	rets = mei_cl_disconnect(cl);

	mei_cl_flush_queues(cl, file);
	cl_dbg(dev, cl, "removing\n");

	mei_cl_unlink(cl);

	file->private_data = NULL;

	kfree(cl);

	mutex_unlock(&dev->device_lock);
	return rets;
}


/**
 * mei_read - the read function.
 *
 * @file: pointer to file structure
 * @ubuf: pointer to user buffer
 * @length: buffer length
 * @offset: data offset in buffer
 *
 * Return: >=0 data length on success , <0 on error
 */
static ssize_t mei_read(struct file *file, char __user *ubuf,
			size_t length, loff_t *offset)
{
	struct mei_cl *cl = file->private_data;
	struct mei_device *dev;
	struct mei_cl_cb *cb = NULL;
	bool nonblock = !!(file->f_flags & O_NONBLOCK);
	ssize_t rets;

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

	dev = cl->dev;


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

	if (length == 0) {
		rets = 0;
		goto out;
	}

	if (ubuf == NULL) {
		rets = -EMSGSIZE;
		goto out;
	}

	cb = mei_cl_read_cb(cl, file);
	if (cb)
		goto copy_buffer;

	if (*offset > 0)
		*offset = 0;

	rets = mei_cl_read_start(cl, length, file);
	if (rets && rets != -EBUSY) {
		cl_dbg(dev, cl, "mei start read failure status = %zd\n", rets);
		goto out;
	}

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

	mutex_unlock(&dev->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(&dev->device_lock);

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

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

copy_buffer:
	/* now copy the data to user space */
	if (cb->status) {
		rets = cb->status;
		cl_dbg(dev, cl,