HID: hid-appletb-kbd: add support for automatic brightness control while using the touchbar

On Windows, if there is no input by the user for 60 sec, the Touch Bar dims
automatically, and after further 15 sec, it turns off. On receiving input,
the Touch Bar resets the timer and goes back to full brightness. This patch
implements the same functionality.

Signed-off-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

Author: AdityaGarg8

drivers/hid/Kconfig

@@ -161,8 +161,10 @@ config HID_APPLETB_BL
 config HID_APPLETB_KBD
 	tristate "Apple Touch Bar Keyboard Mode"
 	depends on USB_HID
+	depends on BACKLIGHT_CLASS_DEVICE
 	depends on INPUT
 	select INPUT_SPARSEKMAP
+	select HID_APPLETB_BL
 	help
 	  Say Y here if you want support for the keyboard mode (escape,
 	  function, media and brightness keys) of Touch Bars on x86 MacBook

drivers/hid/hid-appletb-kbd.c

@@ -16,6 +16,8 @@
 #include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/string.h>
+#include <linux/backlight.h>
+#include <linux/timer.h>
 #include <linux/input/sparse-keymap.h>
 
 #include "hid-ids.h"
@@ -27,6 +29,7 @@
 #define APPLETB_KBD_MODE_MAX	APPLETB_KBD_MODE_OFF
 
 #define APPLETB_DEVID_KEYBOARD	1
+#define APPLETB_DEVID_TRACKPAD	2
 
 #define HID_USAGE_MODE		0x00ff0004
 
@@ -41,14 +44,29 @@ static bool appletb_tb_fn_toggle = true;
 module_param_named(fntoggle, appletb_tb_fn_toggle, bool, 0644);
 MODULE_PARM_DESC(fntoggle, "Switch between Fn and media controls on pressing Fn key");
 
+static bool appletb_tb_autodim = true;
+module_param_named(autodim, appletb_tb_autodim, bool, 0644);
+MODULE_PARM_DESC(autodim, "Automatically dim and turn off the Touch Bar after some time");
+
+static int appletb_tb_dim_timeout = 60;
+module_param_named(dim_timeout, appletb_tb_dim_timeout, int, 0644);
+MODULE_PARM_DESC(dim_timeout, "Dim timeout in sec");
+
+static int appletb_tb_idle_timeout = 15;
+module_param_named(idle_timeout, appletb_tb_idle_timeout, int, 0644);
+MODULE_PARM_DESC(idle_timeout, "Idle timeout in sec");
+
 struct appletb_kbd {
 	struct hid_field *mode_field;
-
-	u8 saved_mode;
-	u8 current_mode;
 	struct input_handler inp_handler;
 	struct input_handle kbd_handle;
-
+	struct input_handle tpd_handle;
+	struct backlight_device *backlight_dev;
+	struct timer_list inactivity_timer;
+	bool has_dimmed;
+	bool has_turned_off;
+	u8 saved_mode;
+	u8 current_mode;
 };
 
 static const struct key_entry appletb_kbd_keymap[] = {
@@ -146,6 +164,34 @@ static int appletb_tb_key_to_slot(unsigned int code)
 	}
 }
 
+static void appletb_inactivity_timer(struct timer_list *t)
+{
+	struct appletb_kbd *kbd = from_timer(kbd, t, inactivity_timer);
+
+	if (kbd->backlight_dev && appletb_tb_autodim) {
+		if (!kbd->has_dimmed) {
+			backlight_device_set_brightness(kbd->backlight_dev, 1);
+			kbd->has_dimmed = true;
+			mod_timer(&kbd->inactivity_timer, jiffies + msecs_to_jiffies(appletb_tb_idle_timeout * 1000));
+		} else if (!kbd->has_turned_off) {
+			backlight_device_set_brightness(kbd->backlight_dev, 0);
+			kbd->has_turned_off = true;
+		}
+	}
+}
+
+static void reset_inactivity_timer(struct appletb_kbd *kbd)
+{
+	if (kbd->backlight_dev && appletb_tb_autodim) {
+		if (kbd->has_dimmed || kbd->has_turned_off) {
+			backlight_device_set_brightness(kbd->backlight_dev, 2);
+			kbd->has_dimmed = false;
+			kbd->has_turned_off = false;
+		}
+		mod_timer(&kbd->inactivity_timer, jiffies + msecs_to_jiffies(appletb_tb_dim_timeout * 1000));
+	}
+}
+
 static int appletb_kbd_hid_event(struct hid_device *hdev, struct hid_field *field,
 				      struct hid_usage *usage, __s32 value)
 {
@@ -170,6 +216,8 @@ static int appletb_kbd_hid_event(struct hid_device *hdev, struct hid_field *fiel
 	if (slot < 0)
 		return 0;
 
+	reset_inactivity_timer(kbd);
+
 	translation = sparse_keymap_entry_from_scancode(input, usage->code);
 
 	if (translation && kbd->current_mode == APPLETB_KBD_MODE_SPCL) {
@@ -186,6 +234,8 @@ static void appletb_kbd_inp_event(struct input_handle *handle, unsigned int type
 {
 	struct appletb_kbd *kbd = handle->private;
 
+	reset_inactivity_timer(kbd);
+
 	if (type == EV_KEY && code == KEY_FN && appletb_tb_fn_toggle) {
 		if (value == 1) {
 			kbd->saved_mode = kbd->current_mode;
@@ -211,6 +261,9 @@ static int appletb_kbd_inp_connect(struct input_handler *handler,
 	if (id->driver_info == APPLETB_DEVID_KEYBOARD) {
 		handle = &kbd->kbd_handle;
 		handle->name = "tbkbd";
+	} else if (id->driver_info == APPLETB_DEVID_TRACKPAD) {
+		handle = &kbd->tpd_handle;
+		handle->name = "tbtpd";
 	} else {
 		return -ENOENT;
 	}
@@ -283,6 +336,15 @@ static const struct input_device_id appletb_kbd_input_devices[] = {
 		.keybit = { [BIT_WORD(KEY_FN)] = BIT_MASK(KEY_FN) },
 		.driver_info = APPLETB_DEVID_KEYBOARD,
 	},
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_BUS |
+			INPUT_DEVICE_ID_MATCH_VENDOR |
+			INPUT_DEVICE_ID_MATCH_KEYBIT,
+		.bustype = BUS_USB,
+		.vendor = USB_VENDOR_ID_APPLE,
+		.keybit = { [BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH) },
+		.driver_info = APPLETB_DEVID_TRACKPAD,
+	},
 	{ }
 };
 
@@ -339,6 +401,15 @@ static int appletb_kbd_probe(struct hid_device *hdev, const struct hid_device_id
 		goto stop_hw;
 	}
 
+	kbd->backlight_dev = backlight_device_get_by_name("appletb_backlight");
+		if (!kbd->backlight_dev)
+			dev_err_probe(dev, ret, "Failed to get backlight device\n");
+		else {
+			backlight_device_set_brightness(kbd->backlight_dev, 2);
+			timer_setup(&kbd->inactivity_timer, appletb_inactivity_timer, 0);
+			mod_timer(&kbd->inactivity_timer, jiffies + msecs_to_jiffies(appletb_tb_dim_timeout * 1000));
+		}
+
 	kbd->inp_handler.event = appletb_kbd_inp_event;
 	kbd->inp_handler.connect = appletb_kbd_inp_connect;
 	kbd->inp_handler.disconnect = appletb_kbd_inp_disconnect;
@@ -377,6 +448,7 @@ static void appletb_kbd_remove(struct hid_device *hdev)
 	appletb_kbd_set_mode(kbd, APPLETB_KBD_MODE_OFF);
 
 	input_unregister_handler(&kbd->inp_handler);
+	del_timer_sync(&kbd->inactivity_timer);
 
 	hid_hw_close(hdev);
 	hid_hw_stop(hdev);
@@ -425,6 +497,9 @@ static struct hid_driver appletb_kbd_hid_driver = {
 };
 module_hid_driver(appletb_kbd_hid_driver);
 
+/* The backlight driver should be loaded before the keyboard driver is initialised*/
+MODULE_SOFTDEP("pre: hid_appletb_bl");
+
 MODULE_AUTHOR("Ronald Tschalär");
 MODULE_AUTHOR("Kerem Karabay <kekrby@gmail.com>");
 MODULE_DESCRIPTION("MacBookPro Touch Bar Keyboard Mode Driver");