wmi-camera.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Lenovo WMI Camera Button Driver
  4 *
  5 * Author: Ai Chao <aichao@kylinos.cn>
  6 * Copyright (C) 2024 KylinSoft Corporation.
  7 */
  8
  9#include <linux/acpi.h>
 10#include <linux/device.h>
 11#include <linux/input.h>
 12#include <linux/types.h>
 13#include <linux/module.h>
 14#include <linux/mutex.h>
 15#include <linux/wmi.h>
 16#include <linux/cleanup.h>
 17
 18#define WMI_LENOVO_CAMERABUTTON_EVENT_GUID "50C76F1F-D8E4-D895-0A3D-62F4EA400013"
 19
 20struct lenovo_wmi_priv {
 21	struct input_dev *idev;
 22	struct mutex notify_lock;	/* lenovo WMI camera button notify lock */
 23};
 24
 25enum {
 26	SW_CAMERA_OFF	= 0,
 27	SW_CAMERA_ON	= 1,
 28};
 29
 30static int camera_shutter_input_setup(struct wmi_device *wdev, u8 camera_mode)
 31{
 32	struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
 33	int err;
 34
 35	priv->idev = input_allocate_device();
 36	if (!priv->idev)
 37		return -ENOMEM;
 38
 39	priv->idev->name = "Lenovo WMI Camera Button";
 40	priv->idev->phys = "wmi/input0";
 41	priv->idev->id.bustype = BUS_HOST;
 42	priv->idev->dev.parent = &wdev->dev;
 43
 44	input_set_capability(priv->idev, EV_SW, SW_CAMERA_LENS_COVER);
 45
 46	input_report_switch(priv->idev, SW_CAMERA_LENS_COVER,
 47			    camera_mode == SW_CAMERA_ON ? 0 : 1);
 48	input_sync(priv->idev);
 49
 50	err = input_register_device(priv->idev);
 51	if (err) {
 52		input_free_device(priv->idev);
 53		priv->idev = NULL;
 54	}
 55
 56	return err;
 57}
 58
 59static void lenovo_wmi_notify(struct wmi_device *wdev, union acpi_object *obj)
 60{
 61	struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
 62	u8 camera_mode;
 63
 64	if (obj->type != ACPI_TYPE_BUFFER) {
 65		dev_err(&wdev->dev, "Bad response type %u\n", obj->type);
 66		return;
 67	}
 68
 69	if (obj->buffer.length != 1) {
 70		dev_err(&wdev->dev, "Invalid buffer length %u\n", obj->buffer.length);
 71		return;
 72	}
 73
 74	/*
 75	 * obj->buffer.pointer[0] is camera mode:
 76	 *      0 camera close
 77	 *      1 camera open
 78	 */
 79	camera_mode = obj->buffer.pointer[0];
 80	if (camera_mode > SW_CAMERA_ON) {
 81		dev_err(&wdev->dev, "Unknown camera mode %u\n", camera_mode);
 82		return;
 83	}
 84
 85	guard(mutex)(&priv->notify_lock);
 86
 87	if (!priv->idev) {
 88		if (camera_shutter_input_setup(wdev, camera_mode))
 89			dev_warn(&wdev->dev, "Failed to register input device\n");
 90		return;
 91	}
 92
 93	if (camera_mode == SW_CAMERA_ON)
 94		input_report_switch(priv->idev, SW_CAMERA_LENS_COVER, 0);
 95	else
 96		input_report_switch(priv->idev, SW_CAMERA_LENS_COVER, 1);
 97	input_sync(priv->idev);
 98}
 99
100static int lenovo_wmi_probe(struct wmi_device *wdev, const void *context)
101{
102	struct lenovo_wmi_priv *priv;
103
104	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
105	if (!priv)
106		return -ENOMEM;
107
108	dev_set_drvdata(&wdev->dev, priv);
109
110	mutex_init(&priv->notify_lock);
111
112	return 0;
113}
114
115static void lenovo_wmi_remove(struct wmi_device *wdev)
116{
117	struct lenovo_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
118
119	if (priv->idev)
120		input_unregister_device(priv->idev);
121
122	mutex_destroy(&priv->notify_lock);
123}
124
125static const struct wmi_device_id lenovo_wmi_id_table[] = {
126	{ .guid_string = WMI_LENOVO_CAMERABUTTON_EVENT_GUID },
127	{  }
128};
129MODULE_DEVICE_TABLE(wmi, lenovo_wmi_id_table);
130
131static struct wmi_driver lenovo_wmi_driver = {
132	.driver = {
133		.name = "lenovo-wmi-camera",
134		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
135	},
136	.id_table = lenovo_wmi_id_table,
137	.no_singleton = true,
138	.probe = lenovo_wmi_probe,
139	.notify = lenovo_wmi_notify,
140	.remove = lenovo_wmi_remove,
141};
142module_wmi_driver(lenovo_wmi_driver);
143
144MODULE_AUTHOR("Ai Chao <aichao@kylinos.cn>");
145MODULE_DESCRIPTION("Lenovo WMI Camera Button Driver");
146MODULE_LICENSE("GPL");