hid-appletb-bl.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Apple Touch Bar Backlight Driver
  4 *
  5 * Copyright (c) 2017-2018 Ronald Tschalär
  6 * Copyright (c) 2022-2023 Kerem Karabay <kekrby@gmail.com>
  7 */
  8
  9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 10
 11#include <linux/hid.h>
 12#include <linux/backlight.h>
 13#include <linux/device.h>
 14
 15#include "hid-ids.h"
 16
 17#define APPLETB_BL_ON			1
 18#define APPLETB_BL_DIM			3
 19#define APPLETB_BL_OFF			4
 20
 21#define HID_UP_APPLEVENDOR_TB_BL	0xff120000
 22
 23#define HID_VD_APPLE_TB_BRIGHTNESS	0xff120001
 24#define HID_USAGE_AUX1			0xff120020
 25#define HID_USAGE_BRIGHTNESS		0xff120021
 26
 27static int appletb_bl_def_brightness = 2;
 28module_param_named(brightness, appletb_bl_def_brightness, int, 0444);
 29MODULE_PARM_DESC(brightness, "Default brightness:\n"
 30			 "    0 - Touchbar is off\n"
 31			 "    1 - Dim brightness\n"
 32			 "    [2] - Full brightness");
 33
 34struct appletb_bl {
 35	struct hid_field *aux1_field, *brightness_field;
 36	struct backlight_device *bdev;
 37
 38	bool full_on;
 39};
 40
 41static const u8 appletb_bl_brightness_map[] = {
 42	APPLETB_BL_OFF,
 43	APPLETB_BL_DIM,
 44	APPLETB_BL_ON,
 45};
 46
 47static int appletb_bl_set_brightness(struct appletb_bl *bl, u8 brightness)
 48{
 49	struct hid_report *report = bl->brightness_field->report;
 50	struct hid_device *hdev = report->device;
 51	int ret;
 52
 53	ret = hid_set_field(bl->aux1_field, 0, 1);
 54	if (ret) {
 55		hid_err(hdev, "Failed to set auxiliary field (%pe)\n", ERR_PTR(ret));
 56		return ret;
 57	}
 58
 59	ret = hid_set_field(bl->brightness_field, 0, brightness);
 60	if (ret) {
 61		hid_err(hdev, "Failed to set brightness field (%pe)\n", ERR_PTR(ret));
 62		return ret;
 63	}
 64
 65	if (!bl->full_on) {
 66		ret = hid_hw_power(hdev, PM_HINT_FULLON);
 67		if (ret < 0) {
 68			hid_err(hdev, "Device didn't power on (%pe)\n", ERR_PTR(ret));
 69			return ret;
 70		}
 71
 72		bl->full_on = true;
 73	}
 74
 75	hid_hw_request(hdev, report, HID_REQ_SET_REPORT);
 76
 77	if (brightness == APPLETB_BL_OFF) {
 78		hid_hw_power(hdev, PM_HINT_NORMAL);
 79		bl->full_on = false;
 80	}
 81
 82	return 0;
 83}
 84
 85static int appletb_bl_update_status(struct backlight_device *bdev)
 86{
 87	struct appletb_bl *bl = bl_get_data(bdev);
 88	u8 brightness;
 89
 90	if (backlight_is_blank(bdev))
 91		brightness = APPLETB_BL_OFF;
 92	else
 93		brightness = appletb_bl_brightness_map[backlight_get_brightness(bdev)];
 94
 95	return appletb_bl_set_brightness(bl, brightness);
 96}
 97
 98static const struct backlight_ops appletb_bl_backlight_ops = {
 99	.options = BL_CORE_SUSPENDRESUME,
100	.update_status = appletb_bl_update_status,
101};
102
103static int appletb_bl_probe(struct hid_device *hdev, const struct hid_device_id *id)
104{
105	struct hid_field *aux1_field, *brightness_field;
106	struct backlight_properties bl_props = { 0 };
107	struct device *dev = &hdev->dev;
108	struct appletb_bl *bl;
109	int ret;
110
111	ret = hid_parse(hdev);
112	if (ret)
113		return dev_err_probe(dev, ret, "HID parse failed\n");
114
115	aux1_field = hid_find_field(hdev, HID_FEATURE_REPORT,
116				    HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_AUX1);
117
118	brightness_field = hid_find_field(hdev, HID_FEATURE_REPORT,
119					  HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_BRIGHTNESS);
120
121	if (!aux1_field || !brightness_field)
122		return -ENODEV;
123
124	if (aux1_field->report != brightness_field->report)
125		return dev_err_probe(dev, -ENODEV, "Encountered unexpected report structure\n");
126
127	bl = devm_kzalloc(dev, sizeof(*bl), GFP_KERNEL);
128	if (!bl)
129		return -ENOMEM;
130
131	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
132	if (ret)
133		return dev_err_probe(dev, ret, "HID hardware start failed\n");
134
135	ret = hid_hw_open(hdev);
136	if (ret) {
137		dev_err_probe(dev, ret, "HID hardware open failed\n");
138		goto stop_hw;
139	}
140
141	bl->aux1_field = aux1_field;
142	bl->brightness_field = brightness_field;
143
144	ret = appletb_bl_set_brightness(bl,
145		appletb_bl_brightness_map[(appletb_bl_def_brightness > 2) ? 2 : appletb_bl_def_brightness]);
146
147	if (ret) {
148		dev_err_probe(dev, ret, "Failed to set default touch bar brightness to %d\n",
149			      appletb_bl_def_brightness);
150		goto close_hw;
151	}
152
153	bl_props.type = BACKLIGHT_RAW;
154	bl_props.max_brightness = ARRAY_SIZE(appletb_bl_brightness_map) - 1;
155
156	bl->bdev = devm_backlight_device_register(dev, "appletb_backlight", dev, bl,
157						  &appletb_bl_backlight_ops, &bl_props);
158	if (IS_ERR(bl->bdev)) {
159		ret = PTR_ERR(bl->bdev);
160		dev_err_probe(dev, ret, "Failed to register backlight device\n");
161		goto close_hw;
162	}
163
164	hid_set_drvdata(hdev, bl);
165
166	return 0;
167
168close_hw:
169	hid_hw_close(hdev);
170stop_hw:
171	hid_hw_stop(hdev);
172
173	return ret;
174}
175
176static void appletb_bl_remove(struct hid_device *hdev)
177{
178	struct appletb_bl *bl = hid_get_drvdata(hdev);
179
180	appletb_bl_set_brightness(bl, APPLETB_BL_OFF);
181
182	hid_hw_close(hdev);
183	hid_hw_stop(hdev);
184}
185
186static const struct hid_device_id appletb_bl_hid_ids[] = {
187	/* MacBook Pro's 2018, 2019, with T2 chip: iBridge DFR Brightness */
188	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
189	{ }
190};
191MODULE_DEVICE_TABLE(hid, appletb_bl_hid_ids);
192
193static struct hid_driver appletb_bl_hid_driver = {
194	.name = "hid-appletb-bl",
195	.id_table = appletb_bl_hid_ids,
196	.probe = appletb_bl_probe,
197	.remove = appletb_bl_remove,
198};
199module_hid_driver(appletb_bl_hid_driver);
200
201MODULE_AUTHOR("Ronald Tschalär");
202MODULE_AUTHOR("Kerem Karabay <kekrby@gmail.com>");
203MODULE_DESCRIPTION("MacBook Pro Touch Bar Backlight driver");
204MODULE_LICENSE("GPL");