[PATCH 3/3] HID: apple-magic-backlight: Add driver for keyboard backlight on internal Magic Keyboards

From: Aditya Garg
Date: Thu Feb 09 2023 - 22:45:33 EST

From: Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>

This driver adds support for the keyboard backlight on Intel T2 Macs
with internal Magic Keyboards (MacBookPro16,x and MacBookAir9,1)

Signed-off-by: Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>
Co-developed-by: Kerem Karabay <kekrby@xxxxxxxxx>
Signed-off-by: Kerem Karabay <kekrby@xxxxxxxxx>
Signed-off-by: Aditya Garg <gargaditya08@xxxxxxxx>
---
MAINTAINERS | 6 ++
drivers/hid/Kconfig | 13 +++
drivers/hid/Makefile | 1 +
drivers/hid/apple-magic-backlight.c | 143 ++++++++++++++++++++++++++++
4 files changed, 163 insertions(+)
create mode 100644 drivers/hid/apple-magic-backlight.c

diff --git a/MAINTAINERS b/MAINTAINERS
index fb1471cb5..3319f0c3e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9201,6 +9201,12 @@ F: include/linux/pm.h
F: include/linux/suspend.h
F: kernel/power/

+HID APPLE MAGIC BACKLIGHT DRIVER
+M: Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>
+L: linux-input@xxxxxxxxxxxxxxx
+S: Maintained
+F: drivers/hid/apple-magic-backlight.c
+
HID CORE LAYER
M: Jiri Kosina <jikos@xxxxxxxxxx>
M: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 4ec669267..ad4612ec5 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -156,6 +156,19 @@ config HID_APPLE_TOUCHBAR
To compile this driver as a module, choose M here: the
module will be called apple-touchbar.

+config HID_APPLE_MAGIC_BACKLIGHT
+ tristate "Apple Magic Keyboard Backlight"
+ depends on USB_HID
+ depends on LEDS_CLASS
+ depends on NEW_LEDS
+ help
+ Say Y here if you want support for the keyboard backlight on Macs with
+ the magic keyboard (MacBookPro16,x and MacBookAir9,1). Note that this
+ driver is not for external magic keyboards.
+
+ To compile this driver as a module, choose M here: the
+ module will be called apple-magic-backlight.
+
config HID_APPLEIR
tristate "Apple infrared receiver"
depends on (USB_HID)
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index c792e42fe..a961914ec 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_HID_ACRUX) += hid-axff.o
obj-$(CONFIG_HID_APPLE) += hid-apple.o
obj-$(CONFIG_HID_APPLE_IBRIDGE) += apple-ibridge.o
obj-$(CONFIG_HID_APPLE_TOUCHBAR) += apple-touchbar.o
+obj-$(CONFIG_HID_APPLE_MAGIC_BACKLIGHT) += apple-magic-backlight.o
obj-$(CONFIG_HID_APPLEIR) += hid-appleir.o
obj-$(CONFIG_HID_CREATIVE_SB0540) += hid-creative-sb0540.o
obj-$(CONFIG_HID_ASUS) += hid-asus.o
diff --git a/drivers/hid/apple-magic-backlight.c b/drivers/hid/apple-magic-backlight.c
new file mode 100644
index 000000000..9b128f6df
--- /dev/null
+++ b/drivers/hid/apple-magic-backlight.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple Magic Keyboard Backlight Driver
+ *
+ * For Intel Macs with internal Magic Keyboard (MacBookPro16,1-4 and MacBookAir9,1)
+ *
+ * Copyright (c) 2022 Kerem Karabay <kekrby@xxxxxxxxx>
+ * Copyright (c) 2023 Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>
+ */
+
+#include <linux/hid.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+
+#define USAGE_MAGIC_BL 0xff00000f
+
+#define APPLE_MAGIC_REPORT_ID_POWER 3
+#define APPLE_MAGIC_REPORT_ID_BRIGHTNESS 1
+
+struct apple_magic_backlight {
+ struct led_classdev cdev;
+ struct hid_device *hdev;
+ struct hid_report *brightness;
+ struct hid_report *power;
+};
+
+static void apple_magic_backlight_power_set(struct apple_magic_backlight *backlight,
+ char power, char rate)
+{
+ struct hid_report *rep = backlight->power;
+
+ rep->field[0]->value[0] = power ? 1 : 0;
+ rep->field[1]->value[0] = 0x5e; /* Mimic Windows */
+ rep->field[1]->value[0] |= rate << 8;
+
+ hid_hw_request(backlight->hdev, backlight->power, HID_REQ_SET_REPORT);
+}
+
+static void apple_magic_backlight_brightness_set(struct apple_magic_backlight *backlight,
+ int brightness, char rate)
+{
+ struct hid_report *rep = backlight->brightness;
+
+ rep->field[0]->value[0] = brightness;
+ rep->field[1]->value[0] = 0x5e; /* Mimic Windows */
+ rep->field[1]->value[0] |= rate << 8;
+
+ hid_hw_request(backlight->hdev, backlight->brightness, HID_REQ_SET_REPORT);
+}
+
+static void apple_magic_backlight_set(struct apple_magic_backlight *backlight,
+ int brightness, char rate)
+{
+ apple_magic_backlight_power_set(backlight, brightness, rate);
+ if (brightness)
+ apple_magic_backlight_brightness_set(backlight, brightness, rate);
+}
+
+static int apple_magic_backlight_led_set(struct led_classdev *led_cdev,
+ enum led_brightness brightness)
+{
+ struct apple_magic_backlight *backlight = container_of(led_cdev,
+ struct apple_magic_backlight, cdev);
+
+ apple_magic_backlight_set(backlight, brightness, 1);
+ return 0;
+}
+
+static int apple_magic_backlight_probe(struct hid_device *hdev,
+ const struct hid_device_id *id)
+{
+ struct apple_magic_backlight *backlight;
+ int rc;
+
+ rc = hid_parse(hdev);
+ if (rc)
+ return rc;
+
+ /* Ensure this usb endpoint is for the keyboard backlight, not touchbar
+ * backlight.
+ */
+ if (!(hdev->collection && hdev->collection[0].usage == USAGE_MAGIC_BL))
+ return -ENODEV;
+
+ backlight = devm_kzalloc(&hdev->dev, sizeof(*backlight), GFP_KERNEL);
+
+ if (!backlight)
+ return -ENOMEM;
+
+ hid_set_drvdata(hdev, backlight);
+
+ rc = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+ if (rc)
+ return rc;
+
+ backlight->brightness = hid_register_report(hdev, HID_FEATURE_REPORT,
+ APPLE_MAGIC_REPORT_ID_BRIGHTNESS, 0);
+ backlight->power = hid_register_report(hdev, HID_FEATURE_REPORT,
+ APPLE_MAGIC_REPORT_ID_POWER, 0);
+
+ if (!backlight->brightness || !backlight->power) {
+ rc = -ENODEV;
+ goto hw_stop;
+ }
+
+ backlight->hdev = hdev;
+ backlight->cdev.name = "apple::kbd_backlight";
+ backlight->cdev.max_brightness = backlight->brightness->field[0]->logical_maximum;
+ backlight->cdev.brightness_set_blocking = apple_magic_backlight_led_set;
+
+ apple_magic_backlight_set(backlight, 0, 0);
+
+ return devm_led_classdev_register(&hdev->dev, &backlight->cdev);
+
+hw_stop:
+ hid_hw_stop(hdev);
+ return rc;
+}
+
+static void apple_magic_backlight_remove(struct hid_device *hdev)
+{
+ hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id apple_magic_backlight_hid_ids[] = {
+ { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
+ { }
+};
+MODULE_DEVICE_TABLE(hid, apple_magic_backlight_hid_ids);
+
+static struct hid_driver apple_magic_backlight_hid_driver = {
+ .name = "apple-magic-backlight",
+ .id_table = apple_magic_backlight_hid_ids,
+ .probe = apple_magic_backlight_probe,
+ .remove = apple_magic_backlight_remove,
+};
+
+module_hid_driver(apple_magic_backlight_hid_driver);
+
+MODULE_DESCRIPTION("MacBook Magic Keyboard Backlight");
+MODULE_AUTHOR("Orlando Chamberlain <orlandoch.dev@xxxxxxxxx>");
+MODULE_LICENSE("GPL");
--
2.37.2