drivers/platform/chrome/cros_ec_dev.c - linux - Git at Google

 /*
  * cros_ec_dev - expose the Chrome OS Embedded Controller to user-space
  *
  * Copyright (C) 2014 Google, Inc.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that 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.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/fs.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>

 #include "cros_ec_dev.h"

 /* Device variables */
 #define CROS_MAX_DEV 128
 static struct class *cros_class;
 static int ec_major;

 /* Basic communication */
 static int ec_get_version(struct cros_ec_device *ec, char *str, int maxlen)
 {
 	struct ec_response_get_version *resp;
 	static const char * const current_image_name[] = {
 		"unknown", "read-only", "read-write", "invalid",
 	};
 	struct cros_ec_command *msg;
 	int ret;

 	msg = kmalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
 	if (!msg)
 		return -ENOMEM;

 	msg->version = 0;
 	msg->command = EC_CMD_GET_VERSION;
 	msg->insize = sizeof(*resp);
 	msg->outsize = 0;

 	ret = cros_ec_cmd_xfer(ec, msg);
 	if (ret < 0)
 		goto exit;

 	if (msg->result != EC_RES_SUCCESS) {
 		snprintf(str, maxlen,
 			 "%s\nUnknown EC version: EC returned %d\n",
 			 CROS_EC_DEV_VERSION, msg->result);
 		ret = -EINVAL;
 		goto exit;
 	}

 	resp = (struct ec_response_get_version *)msg->data;
 	if (resp->current_image >= ARRAY_SIZE(current_image_name))
 		resp->current_image = 3; /* invalid */

 	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
 		 resp->version_string_ro, resp->version_string_rw,
 		 current_image_name[resp->current_image]);

 	ret = 0;
 exit:
 	kfree(msg);
 	return ret;
 }

 /* Device file ops */
 static int ec_device_open(struct inode *inode, struct file *filp)
 {
 	filp->private_data = container_of(inode->i_cdev,
 					  struct cros_ec_device, cdev);
 	return 0;
 }

 static int ec_device_release(struct inode *inode, struct file *filp)
 {
 	return 0;
 }

 static ssize_t ec_device_read(struct file *filp, char __user *buffer,
 			      size_t length, loff_t *offset)
 {
 	struct cros_ec_device *ec = filp->private_data;
 	char msg[sizeof(struct ec_response_get_version) +
 		 sizeof(CROS_EC_DEV_VERSION)];
 	size_t count;
 	int ret;

 	if (*offset != 0)
 		return 0;

 	ret = ec_get_version(ec, msg, sizeof(msg));
 	if (ret)
 		return ret;

 	count = min(length, strlen(msg));

 	if (copy_to_user(buffer, msg, count))
 		return -EFAULT;

 	*offset = count;
 	return count;
 }

 /* Ioctls */
 static long ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg)
 {
 	long ret;
 	struct cros_ec_command u_cmd;
 	struct cros_ec_command *s_cmd;

 	if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
 		return -EFAULT;

 	s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
 			GFP_KERNEL);
 	if (!s_cmd)
 		return -ENOMEM;

 	if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
 		ret = -EFAULT;
 		goto exit;
 	}

 	ret = cros_ec_cmd_xfer(ec, s_cmd);
 	/* Only copy data to userland if data was received. */
 	if (ret < 0)
 		goto exit;

 	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize))
 		ret = -EFAULT;
 exit:
 	kfree(s_cmd);
 	return ret;
 }

 static long ec_device_ioctl_readmem(struct cros_ec_device *ec, void __user *arg)
 {
 	struct cros_ec_readmem s_mem = { };
 	long num;

 	/* Not every platform supports direct reads */
 	if (!ec->cmd_readmem)
 		return -ENOTTY;

 	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
 		return -EFAULT;

 	num = ec->cmd_readmem(ec, s_mem.offset, s_mem.bytes, s_mem.buffer);
 	if (num <= 0)
 		return num;

 	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
 		return -EFAULT;

 	return 0;
 }

 static long ec_device_ioctl(struct file *filp, unsigned int cmd,
 			    unsigned long arg)
 {
 	struct cros_ec_device *ec = filp->private_data;

 	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
 		return -ENOTTY;

 	switch (cmd) {
 	case CROS_EC_DEV_IOCXCMD:
 		return ec_device_ioctl_xcmd(ec, (void __user *)arg);
 	case CROS_EC_DEV_IOCRDMEM:
 		return ec_device_ioctl_readmem(ec, (void __user *)arg);
 	}

 	return -ENOTTY;
 }

 /* Module initialization */
 static const struct file_operations fops = {
 	.open = ec_device_open,
 	.release = ec_device_release,
 	.read = ec_device_read,
 	.unlocked_ioctl = ec_device_ioctl,
 };

 static int ec_device_probe(struct platform_device *pdev)
 {
 	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
 	int retval = -ENOTTY;
 	dev_t devno = MKDEV(ec_major, 0);

 	/* Instantiate it (and remember the EC) */
 	cdev_init(&ec->cdev, &fops);

 	retval = cdev_add(&ec->cdev, devno, 1);
 	if (retval) {
 		dev_err(&pdev->dev, ": failed to add character device\n");
 		return retval;
 	}

 	ec->vdev = device_create(cros_class, NULL, devno, ec,
 				 CROS_EC_DEV_NAME);
 	if (IS_ERR(ec->vdev)) {
 		retval = PTR_ERR(ec->vdev);
 		dev_err(&pdev->dev, ": failed to create device\n");
 		cdev_del(&ec->cdev);
 		return retval;
 	}

 	/* Initialize extra interfaces */
 	ec_dev_sysfs_init(ec);
 	ec_dev_lightbar_init(ec);

 	return 0;
 }

 static int ec_device_remove(struct platform_device *pdev)
 {
 	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);

 	ec_dev_lightbar_remove(ec);
 	ec_dev_sysfs_remove(ec);
 	device_destroy(cros_class, MKDEV(ec_major, 0));
 	cdev_del(&ec->cdev);
 	return 0;
 }

 static struct platform_driver cros_ec_dev_driver = {
 	.driver = {
 		.name = "cros-ec-ctl",
 	},
 	.probe = ec_device_probe,
 	.remove = ec_device_remove,
 };

 static int __init cros_ec_dev_init(void)
 {
 	int ret;
 	dev_t dev = 0;

 	cros_class = class_create(THIS_MODULE, "chromeos");
 	if (IS_ERR(cros_class)) {
 		pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
 		return PTR_ERR(cros_class);
 	}

 	/* Get a range of minor numbers (starting with 0) to work with */
 	ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
 	if (ret < 0) {
 		pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
 		goto failed_chrdevreg;
 	}
 	ec_major = MAJOR(dev);

 	/* Register the driver */
 	ret = platform_driver_register(&cros_ec_dev_driver);
 	if (ret < 0) {
 		pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
 		goto failed_devreg;
 	}
 	return 0;

 failed_devreg:
 	unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
 failed_chrdevreg:
 	class_destroy(cros_class);
 	return ret;
 }

 static void __exit cros_ec_dev_exit(void)
 {
 	platform_driver_unregister(&cros_ec_dev_driver);
 	unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
 	class_destroy(cros_class);
 }

 module_init(cros_ec_dev_init);
 module_exit(cros_ec_dev_exit);

 MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
 MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
 MODULE_VERSION("1.0");
 MODULE_LICENSE("GPL");
	/*
	* cros_ec_dev - expose the Chrome OS Embedded Controller to user-space
	*
	* Copyright (C) 2014 Google, Inc.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that 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.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/fs.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/uaccess.h>

	#include "cros_ec_dev.h"

	/* Device variables */
	#define CROS_MAX_DEV 128
	static struct class *cros_class;
	static int ec_major;

	/* Basic communication */
	static int ec_get_version(struct cros_ec_device ec, char str, int maxlen)
	{
	struct ec_response_get_version *resp;
	static const char * const current_image_name[] = {
	"unknown", "read-only", "read-write", "invalid",
	};
	struct cros_ec_command *msg;
	int ret;

	msg = kmalloc(sizeof(msg) + sizeof(resp), GFP_KERNEL);
	if (!msg)
	return -ENOMEM;

	msg->version = 0;
	msg->command = EC_CMD_GET_VERSION;
	msg->insize = sizeof(*resp);
	msg->outsize = 0;

	ret = cros_ec_cmd_xfer(ec, msg);
	if (ret < 0)
	goto exit;

	if (msg->result != EC_RES_SUCCESS) {
	snprintf(str, maxlen,
	"%s\nUnknown EC version: EC returned %d\n",
	CROS_EC_DEV_VERSION, msg->result);
	ret = -EINVAL;
	goto exit;
	}

	resp = (struct ec_response_get_version *)msg->data;
	if (resp->current_image >= ARRAY_SIZE(current_image_name))
	resp->current_image = 3; /* invalid */

	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
	resp->version_string_ro, resp->version_string_rw,
	current_image_name[resp->current_image]);

	ret = 0;
	exit:
	kfree(msg);
	return ret;
	}

	/* Device file ops */
	static int ec_device_open(struct inode inode, struct file filp)
	{
	filp->private_data = container_of(inode->i_cdev,
	struct cros_ec_device, cdev);
	return 0;
	}

	static int ec_device_release(struct inode inode, struct file filp)
	{
	return 0;
	}

	static ssize_t ec_device_read(struct file filp, char __user buffer,
	size_t length, loff_t *offset)
	{
	struct cros_ec_device *ec = filp->private_data;
	char msg[sizeof(struct ec_response_get_version) +
	sizeof(CROS_EC_DEV_VERSION)];
	size_t count;
	int ret;

	if (*offset != 0)
	return 0;

	ret = ec_get_version(ec, msg, sizeof(msg));
	if (ret)
	return ret;

	count = min(length, strlen(msg));

	if (copy_to_user(buffer, msg, count))
	return -EFAULT;

	*offset = count;
	return count;
	}

	/* Ioctls */
	static long ec_device_ioctl_xcmd(struct cros_ec_device ec, void __user arg)
	{
	long ret;
	struct cros_ec_command u_cmd;
	struct cros_ec_command *s_cmd;

	if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
	return -EFAULT;

	s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
	GFP_KERNEL);
	if (!s_cmd)
	return -ENOMEM;

	if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
	ret = -EFAULT;
	goto exit;
	}

	ret = cros_ec_cmd_xfer(ec, s_cmd);
	/* Only copy data to userland if data was received. */
	if (ret < 0)
	goto exit;

	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize))
	ret = -EFAULT;
	exit:
	kfree(s_cmd);
	return ret;
	}

	static long ec_device_ioctl_readmem(struct cros_ec_device ec, void __user arg)
	{
	struct cros_ec_readmem s_mem = { };
	long num;

	/* Not every platform supports direct reads */
	if (!ec->cmd_readmem)
	return -ENOTTY;

	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
	return -EFAULT;

	num = ec->cmd_readmem(ec, s_mem.offset, s_mem.bytes, s_mem.buffer);
	if (num <= 0)
	return num;

	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
	return -EFAULT;

	return 0;
	}

	static long ec_device_ioctl(struct file *filp, unsigned int cmd,
	unsigned long arg)
	{
	struct cros_ec_device *ec = filp->private_data;

	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
	return -ENOTTY;

	switch (cmd) {
	case CROS_EC_DEV_IOCXCMD:
	return ec_device_ioctl_xcmd(ec, (void __user *)arg);
	case CROS_EC_DEV_IOCRDMEM:
	return ec_device_ioctl_readmem(ec, (void __user *)arg);
	}

	return -ENOTTY;
	}

	/* Module initialization */
	static const struct file_operations fops = {
	.open = ec_device_open,
	.release = ec_device_release,
	.read = ec_device_read,
	.unlocked_ioctl = ec_device_ioctl,
	};

	static int ec_device_probe(struct platform_device *pdev)
	{
	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
	int retval = -ENOTTY;
	dev_t devno = MKDEV(ec_major, 0);

	/* Instantiate it (and remember the EC) */
	cdev_init(&ec->cdev, &fops);

	retval = cdev_add(&ec->cdev, devno, 1);
	if (retval) {
	dev_err(&pdev->dev, ": failed to add character device\n");
	return retval;
	}

	ec->vdev = device_create(cros_class, NULL, devno, ec,
	CROS_EC_DEV_NAME);
	if (IS_ERR(ec->vdev)) {
	retval = PTR_ERR(ec->vdev);
	dev_err(&pdev->dev, ": failed to create device\n");
	cdev_del(&ec->cdev);
	return retval;
	}

	/* Initialize extra interfaces */
	ec_dev_sysfs_init(ec);
	ec_dev_lightbar_init(ec);

	return 0;
	}

	static int ec_device_remove(struct platform_device *pdev)
	{
	struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);

	ec_dev_lightbar_remove(ec);
	ec_dev_sysfs_remove(ec);
	device_destroy(cros_class, MKDEV(ec_major, 0));
	cdev_del(&ec->cdev);
	return 0;
	}

	static struct platform_driver cros_ec_dev_driver = {
	.driver = {
	.name = "cros-ec-ctl",
	},
	.probe = ec_device_probe,
	.remove = ec_device_remove,
	};

	static int __init cros_ec_dev_init(void)
	{
	int ret;
	dev_t dev = 0;

	cros_class = class_create(THIS_MODULE, "chromeos");
	if (IS_ERR(cros_class)) {
	pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
	return PTR_ERR(cros_class);
	}

	/* Get a range of minor numbers (starting with 0) to work with */
	ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
	if (ret < 0) {
	pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
	goto failed_chrdevreg;
	}
	ec_major = MAJOR(dev);

	/* Register the driver */
	ret = platform_driver_register(&cros_ec_dev_driver);
	if (ret < 0) {
	pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
	goto failed_devreg;
	}
	return 0;

	failed_devreg:
	unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
	failed_chrdevreg:
	class_destroy(cros_class);
	return ret;
	}

	static void __exit cros_ec_dev_exit(void)
	{
	platform_driver_unregister(&cros_ec_dev_driver);
	unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
	class_destroy(cros_class);
	}

	module_init(cros_ec_dev_init);
	module_exit(cros_ec_dev_exit);

	MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
	MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
	MODULE_VERSION("1.0");
	MODULE_LICENSE("GPL");