// SPDX-License-Identifier: GPL-2.0+
// Expose the Chromebook Pixel lightbar to userspace
//
// Copyright (C) 2014 Google, Inc.
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kobject.h>
#include <linux/kstrtox.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#define DRV_NAME "cros-ec-lightbar"
/* Rate-limit the lightbar interface to prevent DoS. */
static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
/*
* Whether or not we have given userspace control of the lightbar.
* If this is true, we won't do anything during suspend/resume.
*/
static bool userspace_control;
static ssize_t interval_msec_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
unsigned long msec = lb_interval_jiffies * 1000 / HZ;
return sysfs_emit(buf, "%lu\n", msec);
}
static ssize_t interval_msec_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
unsigned long msec;
if (kstrtoul(buf, 0, &msec))
return -EINVAL;
lb_interval_jiffies = msec * HZ / 1000;
return count;
}
static DEFINE_MUTEX(lb_mutex);
/* Return 0 if able to throttle correctly, error otherwise */
static int lb_throttle(void)
{
static unsigned long last_access;
unsigned long now, next_timeslot;
long delay;
int ret = 0;
mutex_lock(&lb_mutex);
now = jiffies;
next_timeslot = last_access + lb_interval_jiffies;
if (time_before(now, next_timeslot)) {
delay = (long)(next_timeslot) - (long)now;
set_current_state(TASK_INTERRUPTIBLE);
if (schedule_timeout(delay) > 0) {
/* interrupted - just abort */
ret = -EINTR;
goto out;
}
now = jiffies;
}
last_access = now;
out:
mutex_unlock(&lb_mutex);
return ret;
}
static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
{
struct cros_ec_command *msg;
int len;
len = max(sizeof(struct ec_params_lightbar),
sizeof(struct ec_response_lightbar));
msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
if (!msg)
return NULL;
msg->version = 0;
msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
msg->outsize = sizeof(struct ec_params_lightbar);
msg->insize = sizeof(struct ec_response_lightbar);
return msg;
}
static int get_lightbar_version(struct cros_ec_dev *ec,
uint32_t *ver_ptr, uint32_t *flg_ptr)
{
struct ec_params_lightbar *param;
struct ec_response_lightbar *resp;
struct cros_ec_command *msg;
int ret;
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return 0;
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_VERSION;
msg->outsize = sizeof(param->cmd);
msg->result = sizeof(resp->version);
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0 && ret != -EINVAL) {
ret = 0;
goto exit;
}
switch (msg->result) {
case EC_RES_INVALID_PARAM:
/* Pixel had no version command. */
if (ver_ptr)
*ver_ptr = 0;
if (flg_ptr)
*flg_ptr = 0;
ret = 1;
goto exit;
case EC_RES_SUCCESS:
resp = (struct ec_response_lightbar *)msg->data;
/* Future devices w/lightbars should implement this command */
if (ver_ptr)
*ver_ptr = resp->version.num;
if (flg_ptr)
*flg_ptr = resp->version.flags;
ret = 1;
goto exit;
}
/* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
ret = 0;
exit:
kfree(msg);
return ret;
}
static ssize_t version_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
uint32_t version = 0, flags = 0;
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
int ret;
ret = lb_throttle();
if (ret)
return ret;
/* This should always succeed, because we check during init. */
if (!get_lightbar_version(ec, &version, &flags))
return -EIO;
return sysfs_emit(buf, "%d %d\n", version, flags);
}
static ssize_t brightness_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct ec_params_lightbar *param;
struct cros_ec_command *msg;
int ret;
unsigned int val;
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
if (kstrtouint(buf, 0, &val))
return -EINVAL;
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
param->set_brightness.num = val;
ret = lb_throttle();
if (ret)
goto exit;
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0)
goto exit;
ret = count;
exit:
kfree(msg);
return ret;
}
/*
* We expect numbers, and we'll keep reading until we find them, skipping over
* any whitespace (sysfs guarantees that the input is null-terminated). Every
* four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
* parsing error, if we don't parse any numbers, or if we have numbers left
* over.
*/
static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct ec_params_lightbar *param;
struct cros_ec_command *msg;
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
unsigned int val[4];
int ret, i = 0, j = 0, ok = 0;
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
do {
/* Skip any whitespace */
while (*buf && isspace(*buf))
buf++;
if (!*buf)
break;
ret = sscanf(buf, "%i", &val[i++]);
if (ret == 0)
goto exit;
if (i == 4) {
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_SET_RGB;
param->set_rgb.led = val[0];
param->set_rgb.red = val[1];
param->set_rgb.green = val[2];
param->set_rgb.blue = val[3];
/*
* Throttle only the first of every four transactions,
* so that the user can update all four LEDs at once.
*/
if ((j++ % 4) == 0) {
ret = lb_throttle();
if (ret)
goto exit;
}
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0)
goto exit;
i = 0;
ok = 1;
}
/* Skip over the number we just read */
while (*buf && !isspace(*buf))
buf++;
} while (*buf);
exit:
kfree(msg);
return (ok && i == 0) ? count : -EINVAL;
}
static char const *seqname[] = {
"ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
"S0S3", "S3S5", "STOP", "RUN", "KONAMI",
"TAP", "PROGRAM",
};
static ssize_t sequence_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ec_params_lightbar *param;
struct ec_response_lightbar *resp;
struct cros_ec_command *msg;
int ret;
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_GET_SEQ;
ret = lb_throttle();
if (ret)
goto exit;
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0) {
ret = sysfs_emit(buf, "XFER / EC ERROR %d / %d\n", ret, msg->result);
goto exit;
}
resp = (struct ec_response_lightbar *)msg->data;
if (resp->get_seq.num >= ARRAY_SIZE(seqname))
ret = sysfs_emit(buf, "%d\n", resp->get_seq.num);
else
ret = sysfs_emit(buf, "%s\n", seqname[resp->get_seq.num]);
exit:
kfree(msg);
return ret;
}
static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
{
struct ec_params_lightbar *param;
struct cros_ec_command *msg;
int ret;
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
param = (struct ec_params_lightbar *)msg->data;
param->cmd = cmd;
ret = lb_throttle();
if (ret)
goto error;
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0)
goto error;
ret = 0;
error:
kfree(msg);
return ret;
}
static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
{
struct ec_params_lightbar *param;
struct cros_ec_command *msg;
int ret;
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
param->manual_suspend_ctrl.enable = enable;
ret = lb_throttle();
if (ret)
goto error;
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0)
goto error;
ret = 0;
error:
kfree(msg);
return ret;
}
static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct ec_params_lightbar *param;
struct cros_ec_command *msg;
unsigned int num;
int ret, len;
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
for (len = 0; len < count; len++)
if (!isalnum(buf[len]))
break;
for (num = 0; num < ARRAY_SIZE(seqname); num++)
if (!strncasecmp(seqname[num], buf, len))
break;
if (num >= ARRAY_SIZE(seqname)) {
ret = kstrtouint(buf, 0, &num);
if (ret)
return ret;
}
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_SEQ;
param->seq.num = num;
ret = lb_throttle();
if (ret)
goto exit;
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0)
goto exit;
ret = count;
exit:
kfree(msg);
return ret;
}
static ssize_t program_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
int extra_bytes, max_size, ret;
struct ec_params_lightbar *param;
struct cros_ec_command *msg;
struct cros_ec_dev *ec = to_cros_ec_dev(dev);
/*
* We might need to reject the program for size reasons. The EC
* enforces a maximum program size, but we also don't want to try
* and send a program that is too big for the protocol. In order
* to ensure the latter, we also need to ensure we have extra bytes
* to represent the rest of the packet.
*/
extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
if (count > max_size) {
dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
(unsigned int)count, max_size);
return -EINVAL;
}
msg = alloc_lightbar_cmd_msg(ec);
if (!msg)
return -ENOMEM;
ret = lb_throttle();
if (ret)
goto exit;
dev_info(dev, "Copying %zu byte program to EC", count);
param = (struct ec_params_lightbar *)msg->data;
param->cmd = LIGHTBAR_CMD_SET_PROGRAM;
param->set_program.size = count;
memcpy(param->set_program.data, buf, count);
/*
* We need to set the message size manually or else it will use
* EC_LB_PROG_LEN. This might be too long, and the program
* is unlikely to use all of the space.
*/
msg->outsize = count + extra_bytes;
ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
if (ret < 0)
goto exit;
ret = count;
exit:
kfree(msg);
return ret;
}
static ssize_t userspace_control_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sysfs_emit(buf, "%d\n", userspace_control);
}
static ssize_t userspace_control_store(struct device *dev,
struct device_attribute *attr,
const char *buf,
size_t count)
{
bool enable;
int ret;
ret = kstrtobool(buf, &enable);
if (ret < 0)
return ret;
userspace_control = enable;
return count;
}
/* Module initialization */
static DEVICE_ATTR_RW(interval_msec);
static DEVICE_ATTR_RO(version);
static DEVICE_ATTR_WO(brightness);
static DEVICE_ATTR_WO(led_rgb);
static DEVICE_ATTR_RW(sequence);
static DEVICE_ATTR_WO(program);
static DEVICE_ATTR_RW(userspace_control);
static struct attribute *__lb_cmds_attrs[] = {
&dev_attr_interval_msec.attr,
&dev_attr_version.attr,
&dev_attr_brightness.attr,
&dev_attr_led_rgb.attr,
&dev_attr_sequence.attr,
&dev_attr_program.attr,
&dev_attr_userspace_control.attr,
NULL,
};
static const struct attribute_group cros_ec_lightbar_attr_group = {
.name = "lightbar",
.attrs = __lb_cmds_attrs,
};
static int cros_ec_lightbar_probe(struct platform_device *pd)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
struct device *dev = &pd->dev;
int ret;
/*
* Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
* devices like 'cros_pd' doesn't have a lightbar.
*/
if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
return -ENODEV;
/*
* Ask then for the lightbar version, if it's 0 then the 'cros_ec'
* doesn't have a lightbar.
*/
if (!get_lightbar_version(ec_dev, NULL, NULL))
return -ENODEV;
/* Take control of the lightbar from the EC. */
lb_manual_suspend_ctrl(ec_dev, 1);
ret = sysfs_create_group(&ec_dev->class_dev.kobj,
&cros_ec_lightbar_attr_group);
if (ret < 0)
dev_err(dev, "failed to create %s attributes. err=%d\n",
cros_ec_lightbar_attr_group.name, ret);
return ret;
}
static void cros_ec_lightbar_remove(struct platform_device *pd)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
sysfs_remove_group(&ec_dev->class_dev.kobj,
&cros_ec_lightbar_attr_group);
/* Let the EC take over the lightbar again. */
lb_manual_suspend_ctrl(ec_dev, 0);
}
static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
if (userspace_control)
return 0;
return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
}
static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
{
struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
if (userspace_control)
return 0;
return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
}
static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
cros_ec_lightbar_suspend, cros_ec_lightbar_resume);
static const struct platform_device_id cros_ec_lightbar_id[] = {
{ DRV_NAME, 0 },
{}
};
MODULE_DEVICE_TABLE(platform, cros_ec_lightbar_id);
static struct platform_driver cros_ec_lightbar_driver = {
.driver = {
.name = DRV_NAME,
.pm = &cros_ec_lightbar_pm_ops,
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
.probe = cros_ec_lightbar_probe,
.remove_new = cros_ec_lightbar_remove,
.id_table = cros_ec_lightbar_id,
};
module_platform_driver(cros_ec_lightbar_driver);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
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