// SPDX-License-Identifier: GPL-2.0
/*
* Miscellaneous character driver for ChromeOS Embedded Controller
*
* Copyright 2014 Google, Inc.
* Copyright 2019 Google LLC
*
* This file is a rework and part of the code is ported from
* drivers/mfd/cros_ec_dev.c that was originally written by
* Bill Richardson.
*/
#include <linux/init.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/platform_data/cros_ec_chardev.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#define DRV_NAME "cros-ec-chardev"
/* Arbitrary bounded size for the event queue */
#define CROS_MAX_EVENT_LEN PAGE_SIZE
struct chardev_data {
struct cros_ec_dev *ec_dev;
struct miscdevice misc;
};
struct chardev_priv {
struct cros_ec_dev *ec_dev;
struct notifier_block notifier;
wait_queue_head_t wait_event;
unsigned long event_mask;
struct list_head events;
size_t event_len;
};
struct ec_event {
struct list_head node;
size_t size;
u8 event_type;
u8 data[];
};
static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
{
static const char * const current_image_name[] = {
"unknown", "read-only", "read-write", "invalid",
};
struct ec_response_get_version *resp;
struct cros_ec_command *msg;
int ret;
msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
if (!msg)
return -ENOMEM;
msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
msg->insize = sizeof(*resp);
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0) {
snprintf(str, maxlen,
"Unknown EC version, returned error: %d\n",
msg->result);
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;
}
static int cros_ec_chardev_mkbp_event(struct notifier_block *nb,
unsigned long queued_during_suspend,
void *_notify)
{
struct chardev_priv *priv = container_of(nb, struct chardev_priv,
notifier);
struct cros_ec_device *ec_dev = priv->ec_dev->ec_dev;
struct ec_event *event;
unsigned long event_bit = 1 << ec_dev->event_data.event_type;
int total_size = sizeof(*event) + ec_dev->event_size;
if (!(event_bit & priv->event_mask) ||
(priv->event_len + total_size) > CROS_MAX_EVENT_LEN)
return NOTIFY_DONE;
event = kzalloc(total_size, GFP_KERNEL);
if (!event)
return NOTIFY_DONE;
event->size = ec_dev->event_size;
event->event_type = ec_dev->event_data.event_type;
memcpy(event->data, &ec_dev->event_data.data, ec_dev->event_size);
spin_lock(&priv->wait_event.lock);
list_add_tail(&event->node, &priv->events);
priv->event_len += total_size;
wake_up_locked(&priv->wait_event);
spin_unlock(&priv->wait_event.lock);
return NOTIFY_OK;
}
static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv,
bool fetch, bool block)
{
struct ec_event *event;
int err;
spin_lock(&priv->wait_event.lock);
if (!block && list_empty(&priv->events)) {
event = ERR_PTR(-EWOULDBLOCK);
goto out;
}
if (!fetch) {
event = NULL;
goto out;
}
err = wait_event_interruptible_locked(priv->wait_event,
!list_empty(&priv->events));
if (err) {
event = ERR_PTR(err);
goto out;
}
event = list_first_entry(&priv->events, struct ec_event, node);
list_del(&event->node);
priv->event_len -= sizeof(*event) + event->size;
out:
spin_unlock(&priv->wait_event.lock);
return event;
}
/*
* Device file ops
*/
static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
{
struct miscdevice *mdev = filp->private_data;
struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent);
struct chardev_priv *priv;
int ret;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->ec_dev = ec_dev;
filp->private_data = priv;
INIT_LIST_HEAD(&priv->events);
init_waitqueue_head(&priv->wait_event);
nonseekable_open(inode, filp);
priv->notifier.notifier_call = cros_ec_chardev_mkbp_event;
ret = blocking_notifier_chain_register(&ec_dev->ec_dev->event_notifier,
&priv->notifier);
if (ret) {
dev_err(ec_dev->dev, "failed to register event notifier\n");
kfree(priv);
}
return ret;
}
static __poll_t cros_ec_chardev_poll(struct file *filp, poll_table *wait)
{
struct chardev_priv *priv = filp->private_data;
poll_wait(filp, &priv->wait_event, wait);
if (list_empty(&priv->events))
return 0;
return EPOLLIN | EPOLLRDNORM;
}
static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,
size_t length, loff_t *offset)
{
char msg[sizeof(struct ec_response_get_version) +
sizeof(CROS_EC_DEV_VERSION)];
struct chardev_priv *priv = filp->private_data;
struct cros_ec_dev *ec_dev = priv->ec_dev;
size_t count;
int ret;
if (priv->event_mask) { /* queued MKBP event */
struct ec_event *event;
event = cros_ec_chardev_fetch_event(priv, length != 0,
!(filp->f_flags & O_NONBLOCK));
if (IS_ERR(event))
return PTR_ERR(event);
/*
* length == 0 is special - no IO is done but we check
* for error conditions.
*/
if (length == 0)
return 0;
/* The event is 1 byte of type plus the payload */
count = min(length, event->size + 1);
ret = copy_to_user(buffer, &event->event_type, count);
kfree(event);
if (ret) /* the copy failed */
return -EFAULT;
*offset = count;
return count;
}
/*
* Legacy behavior if no event mask is defined
*/
if (*offset != 0)
return 0;
ret = ec_get_version(ec_dev, 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;
}
static int cros_ec_chardev_release(struct inode *inode, struct file *filp)
{
struct chardev_priv *priv = filp->private_data;
struct cros_ec_dev *ec_dev = priv->ec_dev;
struct ec_event *event, *e;
blocking_notifier_chain_unregister(&ec_dev->ec_dev->event_notifier,
&priv->notifier);
list_for_each_entry_safe(event, e, &priv->events, node) {
list_del(&event->node);
kfree(event);
}
kfree(priv);
return 0;
}
/*
* Ioctls
*/
static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
{
struct cros_ec_command *s_cmd;
struct cros_ec_command u_cmd;
long ret;
if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
return -EFAULT;
if (u_cmd.outsize > EC_MAX_MSG_BYTES ||
u_cmd.insize > EC_MAX_MSG_BYTES)
return -EINVAL;
s_cmd = kzalloc(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;
}
if (u_cmd.outsize != s_cmd->outsize ||
u_cmd.insize != s_cmd->insize) {
ret = -EINVAL;
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) + s_cmd->insize))
ret = -EFAULT;
exit:
kfree(s_cmd);
return ret;
}
static long cros_ec_chardev_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;
if (s_mem.bytes > sizeof(s_mem.buffer))
return -EINVAL;
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 num;
}
static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
struct chardev_priv *priv = filp->private_data;
struct cros_ec_dev *ec = priv->ec_dev;
if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
return -ENOTTY;
switch (cmd) {
case CROS_EC_DEV_IOCXCMD:
return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);
case CROS_EC_DEV_IOCRDMEM:
return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);
case CROS_EC_DEV_IOCEVENTMASK:
priv->event_mask = arg;
return 0;
}
return -ENOTTY;
}
static const struct file_operations chardev_fops = {
.open = cros_ec_chardev_open,
.poll = cros_ec_chardev_poll,
.read = cros_ec_chardev_read,
.release = cros_ec_chardev_release,
.unlocked_ioctl = cros_ec_chardev_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = cros_ec_chardev_ioctl,
#endif
};
static int cros_ec_chardev_probe(struct platform_device *pdev)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
struct chardev_data *data;
/* Create a char device: we want to create it anew */
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->ec_dev = ec_dev;
data->misc.minor = MISC_DYNAMIC_MINOR;
data->misc.fops = &chardev_fops;
data->misc.name = ec_platform->ec_name;
data->misc.parent = pdev->dev.parent;
dev_set_drvdata(&pdev->dev, data);
return misc_register(&data->misc);
}
static void cros_ec_chardev_remove(struct platform_device *pdev)
{
struct chardev_data *data = dev_get_drvdata(&pdev->dev);
misc_deregister(&data->misc);
}
static const struct platform_device_id cros_ec_chardev_id[] = {
{ DRV_NAME, 0 },
{}
};
MODULE_DEVICE_TABLE(platform, cros_ec_chardev_id);
static struct platform_driver cros_ec_chardev_driver = {
.driver = {
.name = DRV_NAME,
},
.probe = cros_ec_chardev_probe,
.remove_new = cros_ec_chardev_remove,
.id_table = cros_ec_chardev_id,
};
module_platform_driver(cros_ec_chardev_driver);
MODULE_AUTHOR("Enric Balletbo i Serra <[email protected]>");
MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver");
MODULE_LICENSE("GPL");
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