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1// SPDX-License-Identifier: GPL-2.02/*3 * Driver for the ChromeOS human presence sensor (HPS), attached via I2C.4 *5 * The driver exposes HPS as a character device, although currently no read or6 * write operations are supported. Instead, the driver only controls the power7 * state of the sensor, keeping it on only while userspace holds an open file8 * descriptor to the HPS device.9 *10 * Copyright 2022 Google LLC.11 */12 13#include <linux/acpi.h>14#include <linux/fs.h>15#include <linux/gpio/consumer.h>16#include <linux/i2c.h>17#include <linux/miscdevice.h>18#include <linux/module.h>19#include <linux/pm_runtime.h>20 21#define HPS_ACPI_ID "GOOG0020"22 23struct hps_drvdata {24 struct i2c_client *client;25 struct miscdevice misc_device;26 struct gpio_desc *enable_gpio;27};28 29static void hps_set_power(struct hps_drvdata *hps, bool state)30{31 gpiod_set_value_cansleep(hps->enable_gpio, state);32}33 34static int hps_open(struct inode *inode, struct file *file)35{36 struct hps_drvdata *hps = container_of(file->private_data,37 struct hps_drvdata, misc_device);38 struct device *dev = &hps->client->dev;39 40 return pm_runtime_resume_and_get(dev);41}42 43static int hps_release(struct inode *inode, struct file *file)44{45 struct hps_drvdata *hps = container_of(file->private_data,46 struct hps_drvdata, misc_device);47 struct device *dev = &hps->client->dev;48 49 return pm_runtime_put(dev);50}51 52static const struct file_operations hps_fops = {53 .owner = THIS_MODULE,54 .open = hps_open,55 .release = hps_release,56};57 58static int hps_i2c_probe(struct i2c_client *client)59{60 struct hps_drvdata *hps;61 int ret;62 63 hps = devm_kzalloc(&client->dev, sizeof(*hps), GFP_KERNEL);64 if (!hps)65 return -ENOMEM;66 67 hps->misc_device.parent = &client->dev;68 hps->misc_device.minor = MISC_DYNAMIC_MINOR;69 hps->misc_device.name = "cros-hps";70 hps->misc_device.fops = &hps_fops;71 72 i2c_set_clientdata(client, hps);73 hps->client = client;74 75 /*76 * HPS is powered on from firmware before entering the kernel, so we77 * acquire the line with GPIOD_OUT_HIGH here to preserve the existing78 * state. The peripheral is powered off after successful probe below.79 */80 hps->enable_gpio = devm_gpiod_get(&client->dev, "enable", GPIOD_OUT_HIGH);81 if (IS_ERR(hps->enable_gpio)) {82 ret = PTR_ERR(hps->enable_gpio);83 dev_err(&client->dev, "failed to get enable gpio: %d\n", ret);84 return ret;85 }86 87 ret = misc_register(&hps->misc_device);88 if (ret) {89 dev_err(&client->dev, "failed to initialize misc device: %d\n", ret);90 return ret;91 }92 93 hps_set_power(hps, false);94 pm_runtime_enable(&client->dev);95 return 0;96}97 98static void hps_i2c_remove(struct i2c_client *client)99{100 struct hps_drvdata *hps = i2c_get_clientdata(client);101 102 pm_runtime_disable(&client->dev);103 misc_deregister(&hps->misc_device);104 105 /*106 * Re-enable HPS, in order to return it to its default state107 * (i.e. powered on).108 */109 hps_set_power(hps, true);110}111 112static int hps_suspend(struct device *dev)113{114 struct i2c_client *client = to_i2c_client(dev);115 struct hps_drvdata *hps = i2c_get_clientdata(client);116 117 hps_set_power(hps, false);118 return 0;119}120 121static int hps_resume(struct device *dev)122{123 struct i2c_client *client = to_i2c_client(dev);124 struct hps_drvdata *hps = i2c_get_clientdata(client);125 126 hps_set_power(hps, true);127 return 0;128}129static DEFINE_RUNTIME_DEV_PM_OPS(hps_pm_ops, hps_suspend, hps_resume, NULL);130 131static const struct i2c_device_id hps_i2c_id[] = {132 { "cros-hps", 0 },133 { }134};135MODULE_DEVICE_TABLE(i2c, hps_i2c_id);136 137#ifdef CONFIG_ACPI138static const struct acpi_device_id hps_acpi_id[] = {139 { HPS_ACPI_ID, 0 },140 { }141};142MODULE_DEVICE_TABLE(acpi, hps_acpi_id);143#endif /* CONFIG_ACPI */144 145static struct i2c_driver hps_i2c_driver = {146 .probe = hps_i2c_probe,147 .remove = hps_i2c_remove,148 .id_table = hps_i2c_id,149 .driver = {150 .name = "cros-hps",151 .pm = pm_ptr(&hps_pm_ops),152 .acpi_match_table = ACPI_PTR(hps_acpi_id),153 },154};155module_i2c_driver(hps_i2c_driver);156 157MODULE_ALIAS("acpi:" HPS_ACPI_ID);158MODULE_AUTHOR("Sami Kyöstilä <skyostil@chromium.org>");159MODULE_DESCRIPTION("Driver for ChromeOS HPS");160MODULE_LICENSE("GPL");161