HID: apple: Add support for magic keyboard backlight on T2 Macs

Unlike T2 Macs with Butterfly keyboard, who have their keyboard backlight
on the USB device the T2 Macs with Magic keyboard have their backlight on
the Touchbar backlight device (05ac:8102).

Support for Butterfly keyboards has already been added in
commit 9018eacbe623 ("HID: apple: Add support for keyboard backlight on
certain T2 Macs.") This patch adds support for the Magic keyboards.

Signed-off-by: Orlando Chamberlain <orlandoch.dev@gmail.com>
Co-developed-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Aditya Garg <gargaditya08@live.com>
Link: https://patch.msgid.link/E1D444EA-7FD0-42DA-B198-50B0F03298FB@live.com
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
index bd022e0043569cc84c5323a53749e06f122dbcbe..6dedb84d7cc397107ae52f288db797b009bf6ee1 100644 (file)
--- a/drivers/hid/hid-apple.c
+++ b/drivers/hid/hid-apple.c
@@ -8,6 +8,8 @@
  *  Copyright (c) 2006-2007 Jiri Kosina
  *  Copyright (c) 2008 Jiri Slaby <jirislaby@gmail.com>
  *  Copyright (c) 2019 Paul Pawlowski <paul@mrarm.io>
+ *  Copyright (c) 2023 Orlando Chamberlain <orlandoch.dev@gmail.com>
+ *  Copyright (c) 2024 Aditya Garg <gargaditya08@live.com>
  */
 
 /*
@@ -23,6 +25,7 @@
 #include <linux/timer.h>
 #include <linux/string.h>
 #include <linux/leds.h>
+#include <dt-bindings/leds/common.h>
 
 #include "hid-ids.h"
 
@@ -38,12 +41,17 @@
 #define APPLE_RDESC_BATTERY    BIT(9)
 #define APPLE_BACKLIGHT_CTL    BIT(10)
 #define APPLE_IS_NON_APPLE     BIT(11)
+#define APPLE_MAGIC_BACKLIGHT  BIT(12)
 
 #define APPLE_FLAG_FKEY                0x01
 
 #define HID_COUNTRY_INTERNATIONAL_ISO  13
 #define APPLE_BATTERY_TIMEOUT_MS       60000
 
+#define HID_USAGE_MAGIC_BL                     0xff00000f
+#define APPLE_MAGIC_REPORT_ID_POWER            3
+#define APPLE_MAGIC_REPORT_ID_BRIGHTNESS       1
+
 static unsigned int fnmode = 3;
 module_param(fnmode, uint, 0644);
 MODULE_PARM_DESC(fnmode, "Mode of fn key on Apple keyboards (0 = disabled, "
@@ -81,6 +89,12 @@ struct apple_sc_backlight {
        struct hid_device *hdev;
 };
 
+struct apple_magic_backlight {
+       struct led_classdev cdev;
+       struct hid_report *brightness;
+       struct hid_report *power;
+};
+
 struct apple_sc {
        struct hid_device *hdev;
        unsigned long quirks;
@@ -822,6 +836,66 @@ cleanup_and_exit:
        return ret;
 }
 
+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_init(struct hid_device *hdev)
+{
+       struct apple_magic_backlight *backlight;
+       struct hid_report_enum *report_enum;
+
+       /*
+        * 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;
+
+       report_enum = &hdev->report_enum[HID_FEATURE_REPORT];
+       backlight->brightness = report_enum->report_id_hash[APPLE_MAGIC_REPORT_ID_BRIGHTNESS];
+       backlight->power = report_enum->report_id_hash[APPLE_MAGIC_REPORT_ID_POWER];
+
+       if (!backlight->brightness || !backlight->power)
+               return -ENODEV;
+
+       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);
+
+}
+
 static int apple_probe(struct hid_device *hdev,
                const struct hid_device_id *id)
 {
@@ -860,7 +934,18 @@ static int apple_probe(struct hid_device *hdev,
        if (quirks & APPLE_BACKLIGHT_CTL)
                apple_backlight_init(hdev);
 
+       if (quirks & APPLE_MAGIC_BACKLIGHT) {
+               ret = apple_magic_backlight_init(hdev);
+               if (ret)
+                       goto out_err;
+       }
+
        return 0;
+
+out_err:
+       del_timer_sync(&asc->battery_timer);
+       hid_hw_stop(hdev);
+       return ret;
 }
 
 static void apple_remove(struct hid_device *hdev)
@@ -1073,6 +1158,8 @@ static const struct hid_device_id apple_devices[] = {
                .driver_data = APPLE_HAS_FN | APPLE_ISO_TILDE_QUIRK | APPLE_RDESC_BATTERY },
        { HID_BLUETOOTH_DEVICE(BT_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MAGIC_KEYBOARD_NUMPAD_2021),
                .driver_data = APPLE_HAS_FN | APPLE_ISO_TILDE_QUIRK },
+       { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT),
+               .driver_data = APPLE_MAGIC_BACKLIGHT },
 
        { }
 };