161 lines
3.9 KiB
C
161 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Driver for the ChromeOS human presence sensor (HPS), attached via I2C.
|
|
*
|
|
* The driver exposes HPS as a character device, although currently no read or
|
|
* write operations are supported. Instead, the driver only controls the power
|
|
* state of the sensor, keeping it on only while userspace holds an open file
|
|
* descriptor to the HPS device.
|
|
*
|
|
* Copyright 2022 Google LLC.
|
|
*/
|
|
|
|
#include <linux/acpi.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/gpio/consumer.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/miscdevice.h>
|
|
#include <linux/module.h>
|
|
#include <linux/pm_runtime.h>
|
|
|
|
#define HPS_ACPI_ID "GOOG0020"
|
|
|
|
struct hps_drvdata {
|
|
struct i2c_client *client;
|
|
struct miscdevice misc_device;
|
|
struct gpio_desc *enable_gpio;
|
|
};
|
|
|
|
static void hps_set_power(struct hps_drvdata *hps, bool state)
|
|
{
|
|
gpiod_set_value_cansleep(hps->enable_gpio, state);
|
|
}
|
|
|
|
static int hps_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct hps_drvdata *hps = container_of(file->private_data,
|
|
struct hps_drvdata, misc_device);
|
|
struct device *dev = &hps->client->dev;
|
|
|
|
return pm_runtime_resume_and_get(dev);
|
|
}
|
|
|
|
static int hps_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct hps_drvdata *hps = container_of(file->private_data,
|
|
struct hps_drvdata, misc_device);
|
|
struct device *dev = &hps->client->dev;
|
|
|
|
return pm_runtime_put(dev);
|
|
}
|
|
|
|
static const struct file_operations hps_fops = {
|
|
.owner = THIS_MODULE,
|
|
.open = hps_open,
|
|
.release = hps_release,
|
|
};
|
|
|
|
static int hps_i2c_probe(struct i2c_client *client)
|
|
{
|
|
struct hps_drvdata *hps;
|
|
int ret;
|
|
|
|
hps = devm_kzalloc(&client->dev, sizeof(*hps), GFP_KERNEL);
|
|
if (!hps)
|
|
return -ENOMEM;
|
|
|
|
hps->misc_device.parent = &client->dev;
|
|
hps->misc_device.minor = MISC_DYNAMIC_MINOR;
|
|
hps->misc_device.name = "cros-hps";
|
|
hps->misc_device.fops = &hps_fops;
|
|
|
|
i2c_set_clientdata(client, hps);
|
|
hps->client = client;
|
|
|
|
/*
|
|
* HPS is powered on from firmware before entering the kernel, so we
|
|
* acquire the line with GPIOD_OUT_HIGH here to preserve the existing
|
|
* state. The peripheral is powered off after successful probe below.
|
|
*/
|
|
hps->enable_gpio = devm_gpiod_get(&client->dev, "enable", GPIOD_OUT_HIGH);
|
|
if (IS_ERR(hps->enable_gpio)) {
|
|
ret = PTR_ERR(hps->enable_gpio);
|
|
dev_err(&client->dev, "failed to get enable gpio: %d\n", ret);
|
|
return ret;
|
|
}
|
|
|
|
ret = misc_register(&hps->misc_device);
|
|
if (ret) {
|
|
dev_err(&client->dev, "failed to initialize misc device: %d\n", ret);
|
|
return ret;
|
|
}
|
|
|
|
hps_set_power(hps, false);
|
|
pm_runtime_enable(&client->dev);
|
|
return 0;
|
|
}
|
|
|
|
static void hps_i2c_remove(struct i2c_client *client)
|
|
{
|
|
struct hps_drvdata *hps = i2c_get_clientdata(client);
|
|
|
|
pm_runtime_disable(&client->dev);
|
|
misc_deregister(&hps->misc_device);
|
|
|
|
/*
|
|
* Re-enable HPS, in order to return it to its default state
|
|
* (i.e. powered on).
|
|
*/
|
|
hps_set_power(hps, true);
|
|
}
|
|
|
|
static int hps_suspend(struct device *dev)
|
|
{
|
|
struct i2c_client *client = to_i2c_client(dev);
|
|
struct hps_drvdata *hps = i2c_get_clientdata(client);
|
|
|
|
hps_set_power(hps, false);
|
|
return 0;
|
|
}
|
|
|
|
static int hps_resume(struct device *dev)
|
|
{
|
|
struct i2c_client *client = to_i2c_client(dev);
|
|
struct hps_drvdata *hps = i2c_get_clientdata(client);
|
|
|
|
hps_set_power(hps, true);
|
|
return 0;
|
|
}
|
|
static UNIVERSAL_DEV_PM_OPS(hps_pm_ops, hps_suspend, hps_resume, NULL);
|
|
|
|
static const struct i2c_device_id hps_i2c_id[] = {
|
|
{ "cros-hps", 0 },
|
|
{ }
|
|
};
|
|
MODULE_DEVICE_TABLE(i2c, hps_i2c_id);
|
|
|
|
#ifdef CONFIG_ACPI
|
|
static const struct acpi_device_id hps_acpi_id[] = {
|
|
{ HPS_ACPI_ID, 0 },
|
|
{ }
|
|
};
|
|
MODULE_DEVICE_TABLE(acpi, hps_acpi_id);
|
|
#endif /* CONFIG_ACPI */
|
|
|
|
static struct i2c_driver hps_i2c_driver = {
|
|
.probe = hps_i2c_probe,
|
|
.remove = hps_i2c_remove,
|
|
.id_table = hps_i2c_id,
|
|
.driver = {
|
|
.name = "cros-hps",
|
|
.pm = &hps_pm_ops,
|
|
.acpi_match_table = ACPI_PTR(hps_acpi_id),
|
|
},
|
|
};
|
|
module_i2c_driver(hps_i2c_driver);
|
|
|
|
MODULE_ALIAS("acpi:" HPS_ACPI_ID);
|
|
MODULE_AUTHOR("Sami Kyöstilä <skyostil@chromium.org>");
|
|
MODULE_DESCRIPTION("Driver for ChromeOS HPS");
|
|
MODULE_LICENSE("GPL");
|