[PATCH v3 1/9] HID: hid-appletb-bl: add driver for the backlight of Apple Touch Bars

Aditya Garg
2024-08-08T13:50:43Z

This commit adds a driver for the backlight of Apple Touch Bars on x86
Macs. Note that currently only T2 Macs are supported.

This driver is based on previous work done by Ronald Tschalär
<ronald@innovation.ch>.

Signed-off-by: Kerem Karabay <kekrby@gmail.com>
Co-developed-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Aditya Garg <gargaditya08@live.com>
---
MAINTAINERS | 6 +
drivers/hid/Kconfig | 10 ++
drivers/hid/Makefile | 1 +
drivers/hid/hid-appletb-bl.c | 206 +++++++++++++++++++++++++++++++++++
drivers/hid/hid-quirks.c | 4 +-
5 files changed, 226 insertions(+), 1 deletion(-)
create mode 100644 drivers/hid/hid-appletb-bl.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 8766f3e5e..ac27f41d4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9931,6 +9931,12 @@ F: include/linux/pm.h
F: include/linux/suspend.h
F: kernel/power/

+HID APPLE TOUCH BAR DRIVERS
+M: Kerem Karabay <kekrby@gmail.com>
+L: linux-input@vger.kernel.org
+S: Maintained
+F: drivers/hid/hid-appletb-*
+
HID CORE LAYER
M: Jiri Kosina <jikos@kernel.org>
M: Benjamin Tissoires <bentiss@kernel.org>
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 08446c89e..4988c1fb2 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -148,6 +148,16 @@ config HID_APPLEIR

Say Y here if you want support for Apple infrared remote control.

+config HID_APPLETB_BL
+ tristate "Apple Touch Bar Backlight"
+ depends on BACKLIGHT_CLASS_DEVICE
+ help
+ Say Y here if you want support for the backlight of Touch Bars on x86
+ MacBook Pros.
+
+ To compile this driver as a module, choose M here: the
+ module will be called hid-appletb-bl.
+
config HID_ASUS
tristate "Asus"
depends on USB_HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index e40f1ddeb..1d825a474 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_HID_ALPS) += hid-alps.o
obj-$(CONFIG_HID_ACRUX) += hid-axff.o
obj-$(CONFIG_HID_APPLE) += hid-apple.o
obj-$(CONFIG_HID_APPLEIR) += hid-appleir.o
+obj-$(CONFIG_HID_APPLETB_BL) += hid-appletb-bl.o
obj-$(CONFIG_HID_CREATIVE_SB0540) += hid-creative-sb0540.o
obj-$(CONFIG_HID_ASUS) += hid-asus.o
obj-$(CONFIG_HID_AUREAL) += hid-aureal.o
diff --git a/drivers/hid/hid-appletb-bl.c b/drivers/hid/hid-appletb-bl.c
new file mode 100644
index 000000000..00bbe45df
--- /dev/null
+++ b/drivers/hid/hid-appletb-bl.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple Touch Bar Backlight Driver
+ *
+ * Copyright (c) 2017-2018 Ronald Tschalär
+ * Copyright (c) 2022-2023 Kerem Karabay <kekrby@gmail.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/hid.h>
+#include <linux/backlight.h>
+
+#include "hid-ids.h"
+
+#define APPLETB_BL_ON 1
+#define APPLETB_BL_DIM 3
+#define APPLETB_BL_OFF 4
+
+#define HID_UP_APPLEVENDOR_TB_BL 0xff120000
+
+#define HID_VD_APPLE_TB_BRIGHTNESS 0xff120001
+#define HID_USAGE_AUX1 0xff120020
+#define HID_USAGE_BRIGHTNESS 0xff120021
+
+static int appletb_bl_def_brightness = 2;
+module_param_named(brightness, appletb_bl_def_brightness, int, 0444);
+MODULE_PARM_DESC(brightness, "Default brightness:\n"
+ " 0 - Touchbar is off\n"
+ " 1 - Dim brightness\n"
+ " [2] - Full brightness");
+
+struct appletb_bl {
+ struct hid_field *aux1_field, *brightness_field;
+ struct backlight_device *bdev;
+
+ bool full_on;
+};
+
+const u8 appletb_bl_brightness_map[] = {
+ APPLETB_BL_OFF,
+ APPLETB_BL_DIM,
+ APPLETB_BL_ON
+};
+
+static int appletb_bl_set_brightness(struct appletb_bl *bl, u8 brightness)
+{
+ struct hid_report *report = bl->brightness_field->report;
+ struct hid_device *hdev = report->device;
+ int ret;
+
+ ret = hid_set_field(bl->aux1_field, 0, 1);
+ if (ret) {
+ hid_err(hdev, "Failed to set auxiliary field (%pe)\n", ERR_PTR(ret));
+ return ret;
+ }
+
+ ret = hid_set_field(bl->brightness_field, 0, brightness);
+ if (ret) {
+ hid_err(hdev, "Failed to set brightness field (%pe)\n", ERR_PTR(ret));
+ return ret;
+ }
+
+ if (!bl->full_on) {
+ ret = hid_hw_power(hdev, PM_HINT_FULLON);
+ if (ret < 0) {
+ hid_err(hdev, "Device didn't power on (%pe)\n", ERR_PTR(ret));
+ return ret;
+ }
+
+ bl->full_on = true;
+ }
+
+ hid_hw_request(hdev, report, HID_REQ_SET_REPORT);
+
+ if (brightness == APPLETB_BL_OFF) {
+ hid_hw_power(hdev, PM_HINT_NORMAL);
+ bl->full_on = false;
+ }
+
+ return 0;
+}
+
+static int appletb_bl_update_status(struct backlight_device *bdev)
+{
+ struct appletb_bl *bl = bl_get_data(bdev);
+ u16 brightness;
+
+ if (bdev->props.state & BL_CORE_SUSPENDED)
+ brightness = 0;
+ else
+ brightness = backlight_get_brightness(bdev);
+
+ return appletb_bl_set_brightness(bl, appletb_bl_brightness_map[brightness]);
+}
+
+static const struct backlight_ops appletb_bl_backlight_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = appletb_bl_update_status,
+};
+
+static int appletb_bl_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+ struct hid_field *aux1_field, *brightness_field;
+ struct backlight_properties bl_props = { 0 };
+ struct device *dev = &hdev->dev;
+ struct appletb_bl *bl;
+ int ret;
+
+ ret = hid_parse(hdev);
+ if (ret)
+ return dev_err_probe(dev, ret, "HID parse failed\n");
+
+ aux1_field = hid_find_field(hdev, HID_FEATURE_REPORT,
+ HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_AUX1);
+
+ brightness_field = hid_find_field(hdev, HID_FEATURE_REPORT,
+ HID_VD_APPLE_TB_BRIGHTNESS, HID_USAGE_BRIGHTNESS);
+
+ if (!aux1_field || !brightness_field)
+ return -ENODEV;
+
+ if (aux1_field->report != brightness_field->report)
+ return dev_err_probe(dev, -ENODEV, "Encountered unexpected report structure\n");
+
+ bl = devm_kzalloc(dev, sizeof(*bl), GFP_KERNEL);
+ if (!bl)
+ return -ENOMEM;
+
+ ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
+ if (ret)
+ return dev_err_probe(dev, ret, "HID hardware start failed\n");
+
+ ret = hid_hw_open(hdev);
+ if (ret) {
+ dev_err_probe(dev, ret, "HID hardware open failed\n");
+ goto stop_hw;
+ }
+
+ bl->aux1_field = aux1_field;
+ bl->brightness_field = brightness_field;
+
+ if (appletb_bl_def_brightness == 0)
+ ret = appletb_bl_set_brightness(bl, APPLETB_BL_OFF);
+ else if (appletb_bl_def_brightness == 1)
+ ret = appletb_bl_set_brightness(bl, APPLETB_BL_DIM);
+ else
+ ret = appletb_bl_set_brightness(bl, APPLETB_BL_ON);
+
+ if (ret) {
+ dev_err_probe(dev, ret, "Failed to set touch bar brightness to off\n");
+ goto close_hw;
+ }
+
+ bl_props.type = BACKLIGHT_RAW;
+ bl_props.max_brightness = ARRAY_SIZE(appletb_bl_brightness_map) - 1;
+
+ bl->bdev = devm_backlight_device_register(dev, "appletb_backlight", dev, bl,
+ &appletb_bl_backlight_ops, &bl_props);
+ if (IS_ERR(bl->bdev)) {
+ ret = PTR_ERR(bl->bdev);
+ dev_err_probe(dev, ret, "Failed to register backlight device\n");
+ goto close_hw;
+ }
+
+ hid_set_drvdata(hdev, bl);
+
+ return 0;
+
+close_hw:
+ hid_hw_close(hdev);
+stop_hw:
+ hid_hw_stop(hdev);
+
+ return ret;
+}
+
+static void appletb_bl_remove(struct hid_device *hdev)
+{
+ struct appletb_bl *bl = hid_get_drvdata(hdev);
+
+ appletb_bl_set_brightness(bl, APPLETB_BL_OFF);
+
+ hid_hw_close(hdev);
+ hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id appletb_bl_hid_ids[] = {
+ /* MacBook Pro's 2018, 2019, with T2 chip: iBridge DFR Brightness */
+ { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
+ { }
+};
+MODULE_DEVICE_TABLE(hid, appletb_bl_hid_ids);
+
+static struct hid_driver appletb_bl_hid_driver = {
+ .name = "hid-appletb-bl",
+ .id_table = appletb_bl_hid_ids,
+ .probe = appletb_bl_probe,
+ .remove = appletb_bl_remove,
+};
+module_hid_driver(appletb_bl_hid_driver);
+
+MODULE_AUTHOR("Ronald Tschalär");
+MODULE_AUTHOR("Kerem Karabay <kekrby@gmail.com>");
+MODULE_DESCRIPTION("MacBookPro Touch Bar Backlight Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
index e0bbf0c63..818d41a35 100644
--- a/drivers/hid/hid-quirks.c
+++ b/drivers/hid/hid-quirks.c
@@ -328,7 +328,6 @@ static const struct hid_device_id hid_have_special_driver[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_GEYSER1_TP_ONLY) },
{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MAGIC_KEYBOARD_2021) },
{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MAGIC_KEYBOARD_FINGERPRINT_2021) },
- { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_DISPLAY) },
#endif
#if IS_ENABLED(CONFIG_HID_APPLEIR)
@@ -338,6 +337,9 @@ static const struct hid_device_id hid_have_special_driver[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_IRCONTROL4) },
{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_IRCONTROL5) },
#endif
+#if IS_ENABLED(CONFIG_HID_APPLETB_BL)
+ { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
+#endif
#if IS_ENABLED(CONFIG_HID_ASUS)
{ HID_I2C_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_I2C_KEYBOARD) },
{ HID_I2C_DEVICE(USB_VENDOR_ID_ASUSTEK, USB_DEVICE_ID_ASUSTEK_I2C_TOUCHPAD) },
--
2.43.0