4002-keyboard-backlight.patch

diff --git a/drivers/hid/hid-apple.c b/drivers/hid/hid-apple.c
index b1143139599a..73d3c083112e 100644
--- a/drivers/hid/hid-apple.c
+++ b/drivers/hid/hid-apple.c
@@ -7,6 +7,7 @@
  *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
  *  Copyright (c) 2006-2007 Jiri Kosina
  *  Copyright (c) 2008 Jiri Slaby <jirislaby@gmail.com>
+ *  Copyright (c) 2019 Paul Pawlowski <paul@mrarm.io>
  */
 
 /*
@@ -30,6 +31,7 @@
 #define APPLE_INVERT_HWHEEL	0x0040
 #define APPLE_IGNORE_HIDINPUT	0x0080
 #define APPLE_NUMLOCK_EMULATION	0x0100
+#define APPLE_BACKLIGHT_CTL	0x0200
 
 #define APPLE_FLAG_FKEY		0x01
 
@@ -51,10 +53,17 @@ MODULE_PARM_DESC(swap_opt_cmd, "Swap the Option (\"Alt\") and Command (\"Flag\")
 		"(For people who want to keep Windows PC keyboard muscle memory. "
 		"[0] = as-is, Mac layout. 1 = swapped, Windows layout.)");
 
+struct apple_sc_backlight {
+	struct led_classdev cdev;
+	struct hid_device *hdev;
+	unsigned short backlight_off, backlight_on_min, backlight_on_max;
+};
+
 struct apple_sc {
 	unsigned long quirks;
 	unsigned int fn_on;
 	DECLARE_BITMAP(pressed_numlock, KEY_CNT);
+	struct apple_sc_backlight *backlight;
 };
 
 struct apple_key_translation {
@@ -162,6 +171,19 @@ static const struct apple_key_translation swapped_option_cmd_keys[] = {
 	{ }
 };
 
+struct apple_backlight_config_report {
+	u8 report_id;
+	u8 version;
+	u16 backlight_off, backlight_on_min, backlight_on_max;
+};
+
+struct apple_backlight_set_report {
+	u8 report_id;
+	u8 version;
+	u16 backlight;
+	u16 rate;
+};
+
 static const struct apple_key_translation *apple_find_translation(
 		const struct apple_key_translation *table, u16 from)
 {
@@ -370,6 +392,101 @@ static int apple_input_mapped(struct hid_device *hdev, struct hid_input *hi,
 	return 0;
 }
 
+static bool apple_backlight_check_support(struct hid_device *hdev)
+{
+	int i;
+	unsigned hid;
+	struct hid_report *report;
+
+	list_for_each_entry(report, &hdev->report_enum[HID_INPUT_REPORT].report_list, list) {
+		for (i = 0; i < report->maxfield; i++) {
+			hid = report->field[i]->usage->hid;
+			if ((hid & HID_USAGE_PAGE) == HID_UP_MSVENDOR && (hid & HID_USAGE) == 0xf)
+				return true;
+		}
+	}
+
+	return false;
+}
+
+static int apple_backlight_set(struct hid_device *hdev, u16 value, u16 rate)
+{
+	int ret = 0;
+	struct apple_backlight_set_report *rep;
+
+	rep = kmalloc(sizeof(*rep), GFP_KERNEL);
+	if (rep == NULL)
+		return -ENOMEM;
+
+	rep->report_id = 0xB0;
+	rep->version = 1;
+	rep->backlight = value;
+	rep->rate = rate;
+
+	ret = hid_hw_raw_request(hdev, 0xB0u, (u8 *) rep, sizeof(*rep), HID_OUTPUT_REPORT, HID_REQ_SET_REPORT);
+
+	kfree(rep);
+	return ret;
+}
+
+static int apple_backlight_led_set(struct led_classdev *led_cdev,
+	enum led_brightness brightness)
+{
+	struct apple_sc_backlight *backlight = container_of(led_cdev, struct apple_sc_backlight, cdev);
+	return apple_backlight_set(backlight->hdev, brightness, 0);
+}
+
+static int apple_backlight_init(struct hid_device *hdev)
+{
+	int ret;
+	struct apple_sc *asc = hid_get_drvdata(hdev);
+	struct apple_backlight_config_report *rep;
+
+	if (!apple_backlight_check_support(hdev))
+		return -EINVAL;
+
+	rep = kmalloc(0x200, GFP_KERNEL);
+	if (rep == NULL)
+		return -ENOMEM;
+
+	ret = hid_hw_raw_request(hdev, 0xBFu, (u8 *) rep, sizeof(*rep), HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
+	if (ret < 0) {
+		hid_err(hdev, "backlight request failed: %d\n", ret);
+		goto cleanup_and_exit;
+	}
+	if (ret < 8 || rep->version != 1) {
+		hid_err(hdev, "backlight config struct: bad version %i\n", rep->version);
+		ret = -EINVAL;
+		goto cleanup_and_exit;
+	}
+
+	hid_dbg(hdev, "backlight config: off=%u, on_min=%u, on_max=%u\n",
+		rep->backlight_off, rep->backlight_on_min, rep->backlight_on_max);
+
+	asc->backlight = devm_kzalloc(&hdev->dev, sizeof(*asc->backlight), GFP_KERNEL);
+	if (!asc->backlight) {
+		ret = -ENOMEM;
+		goto cleanup_and_exit;
+	}
+
+	asc->backlight->hdev = hdev;
+	asc->backlight->cdev.name = "apple::kbd_backlight";
+	asc->backlight->cdev.max_brightness = rep->backlight_on_max;
+	asc->backlight->cdev.brightness_set_blocking = apple_backlight_led_set;
+
+	ret = apple_backlight_set(hdev, 0, 0);
+	if (ret < 0) {
+		hid_err(hdev, "backlight set request failed: %d\n", ret);
+		goto cleanup_and_exit;
+	}
+
+	ret = devm_led_classdev_register(&hdev->dev, &asc->backlight->cdev);
+
+cleanup_and_exit:
+	kfree(rep);
+	return ret;
+}
+
 static int apple_probe(struct hid_device *hdev,
 		const struct hid_device_id *id)
 {
@@ -405,6 +522,12 @@ static int apple_probe(struct hid_device *hdev,
 		return ret;
 	}
 
+	if (quirks & APPLE_BACKLIGHT_CTL) {
+		ret = apple_backlight_init(hdev);
+		if (ret < 0)
+			hid_warn(hdev, "backlight init failed: %d\n", ret);
+	}
+
 	return 0;
 }
 
@@ -562,15 +685,15 @@ static const struct hid_device_id apple_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRING9_JIS),
 		.driver_data = APPLE_HAS_FN | APPLE_RDESC_JIS },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRING10_T2_A),
-		.driver_data = APPLE_HAS_FN },
+		.driver_data = APPLE_HAS_FN | APPLE_BACKLIGHT_CTL },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRING10_T2_B),
-		.driver_data = APPLE_HAS_FN },
+		.driver_data = APPLE_HAS_FN | APPLE_BACKLIGHT_CTL },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRING10_T2_C),
-		.driver_data = APPLE_HAS_FN },
+		.driver_data = APPLE_HAS_FN | APPLE_BACKLIGHT_CTL },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRING10_T2_D),
-		.driver_data = APPLE_HAS_FN },
+		.driver_data = APPLE_HAS_FN | APPLE_BACKLIGHT_CTL },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_WELLSPRING11_T2),
-		.driver_data = APPLE_HAS_FN },
+		.driver_data = APPLE_HAS_FN | APPLE_BACKLIGHT_CTL },
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_ALU_WIRELESS_2009_ANSI),
 		.driver_data = APPLE_NUMLOCK_EMULATION | APPLE_HAS_FN },
 	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_ALU_WIRELESS_2009_ISO),