[PATCH v4 2/2] HID: hid-apple-magic-backlight: Add driver for keyboard backlight on internal Magic Keyboards

Orlando Chamberlain
2023-02-18T09:08:09Z

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

Co-developed-by: Kerem Karabay <kekrby@gmail.com>
Signed-off-by: Kerem Karabay <kekrby@gmail.com>
Signed-off-by: Orlando Chamberlain <orlandoch.dev@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
---
v3->v4:
- collect reviews from Andy and Thomas
- remove now unused hdev member of apple_magic_backlight
v2->v3:
- remove unneeded inclusion
- use s32 for report value type
- remove unneeded null check
- don't set drvdata as its never used
- prepend "hid-" to module name
v1->v2:
- drop unneeded remove function
- combine set functions
- add missing header inclusions
- avoid char as argument in favour of u8
- handful of style/formatting fixes
- use standard led name ":white:kbd_backlight"
- rename USAGE_MAGIC_BL to HID_USAGE_MAGIC_BL

MAINTAINERS | 6 ++
drivers/hid/Kconfig | 13 +++
drivers/hid/Makefile | 1 +
drivers/hid/hid-apple-magic-backlight.c | 120 ++++++++++++++++++++++++
4 files changed, 140 insertions(+)
create mode 100644 drivers/hid/hid-apple-magic-backlight.c

diff --git a/MAINTAINERS b/MAINTAINERS
index fb1471cb5ed3..3319f0c3ed1e 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@gmail.com>
+L: linux-input@vger.kernel.org
+S: Maintained
+F: drivers/hid/apple-magic-backlight.c
+
HID CORE LAYER
M: Jiri Kosina <jikos@kernel.org>
M: Benjamin Tissoires <benjamin.tissoires@redhat.com>
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index e2a5d30c8895..fe489632bfd9 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -130,6 +130,19 @@ config HID_APPLE
Say Y here if you want support for keyboards of Apple iBooks, PowerBooks,
MacBooks, MacBook Pros and Apple Aluminum.

+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 hid-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 e8014c1a2f8b..dc8df002bc86 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_HID_ACCUTOUCH) += hid-accutouch.o
obj-$(CONFIG_HID_ALPS) += hid-alps.o
obj-$(CONFIG_HID_ACRUX) += hid-axff.o
obj-$(CONFIG_HID_APPLE) += hid-apple.o
+obj-$(CONFIG_HID_APPLE_MAGIC_BACKLIGHT) += hid-apple-magic-backlight.o
obj-$(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/hid-apple-magic-backlight.c b/drivers/hid/hid-apple-magic-backlight.c
new file mode 100644
index 000000000000..f0fc02ff3b2d
--- /dev/null
+++ b/drivers/hid/hid-apple-magic-backlight.c
@@ -0,0 +1,120 @@
+// 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@gmail.com>
+ * Copyright (c) 2023 Orlando Chamberlain <orlandoch.dev@gmail.com>
+ */
+
+#include <linux/hid.h>
+#include <linux/leds.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <dt-bindings/leds/common.h>
+
+#include "hid-ids.h"
+
+#define HID_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_report *brightness;
+ struct hid_report *power;
+};
+
+static void apple_magic_backlight_report_set(struct hid_report *rep, s32 value, u8 rate)
+{
+ rep->field[0]->value[0] = value;
+ rep->field[1]->value[0] = 0x5e; /* Mimic Windows */
+ rep->field[1]->value[0] |= rate << 8;
+
+ hid_hw_request(rep->device, rep, HID_REQ_SET_REPORT);
+}
+
+static void apple_magic_backlight_set(struct apple_magic_backlight *backlight,
+ int brightness, char rate)
+{
+ apple_magic_backlight_report_set(backlight->power, brightness ? 1 : 0, rate);
+ if (brightness)
+ apple_magic_backlight_report_set(backlight->brightness, 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[0].usage != HID_USAGE_MAGIC_BL)
+ return -ENODEV;
+
+ backlight = devm_kzalloc(&hdev->dev, sizeof(*backlight), GFP_KERNEL);
+ if (!backlight)
+ return -ENOMEM;
+
+ 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->cdev.name = ":white:" LED_FUNCTION_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 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 = "hid-apple-magic-backlight",
+ .id_table = apple_magic_backlight_hid_ids,
+ .probe = apple_magic_backlight_probe,
+};
+module_hid_driver(apple_magic_backlight_hid_driver);
+
+MODULE_DESCRIPTION("MacBook Magic Keyboard Backlight");
+MODULE_AUTHOR("Orlando Chamberlain <orlandoch.dev@gmail.com>");
+MODULE_LICENSE("GPL");
--
2.39.1