linux/drivers/platform/chrome/cros_ec_dev.c

346 lines
8.1 KiB
C

/*
* 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 int ec_major;
static const struct attribute_group *cros_ec_groups[] = {
&cros_ec_attr_group,
&cros_ec_lightbar_attr_group,
NULL,
};
static struct class cros_class = {
.owner = THIS_MODULE,
.name = "chromeos",
.dev_groups = cros_ec_groups,
};
/* Basic communication */
static int ec_get_version(struct cros_ec_dev *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 + ec->cmd_offset;
msg->insize = sizeof(*resp);
msg->outsize = 0;
ret = cros_ec_cmd_xfer(ec->ec_dev, 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)
{
struct cros_ec_dev *ec = container_of(inode->i_cdev,
struct cros_ec_dev, cdev);
filp->private_data = ec;
nonseekable_open(inode, filp);
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_dev *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_dev *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;
}
s_cmd->command += ec->cmd_offset;
ret = cros_ec_cmd_xfer(ec->ec_dev, 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_dev *ec, void __user *arg)
{
struct cros_ec_device *ec_dev = ec->ec_dev;
struct cros_ec_readmem s_mem = { };
long num;
/* Not every platform supports direct reads */
if (!ec_dev->cmd_readmem)
return -ENOTTY;
if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
return -EFAULT;
num = ec_dev->cmd_readmem(ec_dev, 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_dev *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 void __remove(struct device *dev)
{
struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
class_dev);
kfree(ec);
}
static int ec_device_probe(struct platform_device *pdev)
{
int retval = -ENOMEM;
struct device *dev = &pdev->dev;
struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
dev_t devno = MKDEV(ec_major, pdev->id);
struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
if (!ec)
return retval;
dev_set_drvdata(dev, ec);
ec->ec_dev = dev_get_drvdata(dev->parent);
ec->dev = dev;
ec->cmd_offset = ec_platform->cmd_offset;
device_initialize(&ec->class_dev);
cdev_init(&ec->cdev, &fops);
/*
* Add the character device
* Link cdev to the class device to be sure device is not used
* before unbinding it.
*/
ec->cdev.kobj.parent = &ec->class_dev.kobj;
retval = cdev_add(&ec->cdev, devno, 1);
if (retval) {
dev_err(dev, ": failed to add character device\n");
goto cdev_add_failed;
}
/*
* Add the class device
* Link to the character device for creating the /dev entry
* in devtmpfs.
*/
ec->class_dev.devt = ec->cdev.dev;
ec->class_dev.class = &cros_class;
ec->class_dev.parent = dev;
ec->class_dev.release = __remove;
retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
if (retval) {
dev_err(dev, "dev_set_name failed => %d\n", retval);
goto set_named_failed;
}
retval = device_add(&ec->class_dev);
if (retval) {
dev_err(dev, "device_register failed => %d\n", retval);
goto dev_reg_failed;
}
return 0;
dev_reg_failed:
set_named_failed:
dev_set_drvdata(dev, NULL);
cdev_del(&ec->cdev);
cdev_add_failed:
kfree(ec);
return retval;
}
static int ec_device_remove(struct platform_device *pdev)
{
struct cros_ec_dev *ec = dev_get_drvdata(&pdev->dev);
cdev_del(&ec->cdev);
device_unregister(&ec->class_dev);
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;
ret = class_register(&cros_class);
if (ret) {
pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
return ret;
}
/* 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_unregister(&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_unregister(&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");