diff options
Diffstat (limited to 'drivers/platform/chrome/cros_hps_i2c.c')
| -rw-r--r-- | drivers/platform/chrome/cros_hps_i2c.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/drivers/platform/chrome/cros_hps_i2c.c b/drivers/platform/chrome/cros_hps_i2c.c new file mode 100644 index 000000000000..92da59d94745 --- /dev/null +++ b/drivers/platform/chrome/cros_hps_i2c.c @@ -0,0 +1,162 @@ +// 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 int 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); + + return 0; +} + +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_new = 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"); |