platform: x86: dell-laptop: Add support for keyboard backlight

This patch adds the support for the configuration of the keyboard
backlight on supported Dell laptops.

With this patch it is possible to set:
* keyboard backlight level
* timeout after which the backlight will be automatically turned off
* input activity triggers (keyboard, touchpad, mouse) that enable the backlight
* ambient light settings

The settings are exposed via /sys/class/leds/dell::kbd_backlight/

The code is based on the newly released documentation by Dell in the
libsmbios project.
Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

Documentation/ABI/testing/sysfs-platform-dell-laptop

+What:		/sys/class/leds/dell::kbd_backlight/als_enabled
+Date:		December 2014
+KernelVersion:	3.19
+Contact:	Gabriele Mazzotta <gabriele.mzt@gmail.com>,
+		Pali Rohár <pali.rohar@gmail.com>
+Description:
+		This file allows to control the automatic keyboard
+		illumination mode on some systems that have an ambient
+		light sensor. Write 1 to this file to enable the auto
+		mode, 0 to disable it.
+
+What:		/sys/class/leds/dell::kbd_backlight/als_setting
+Date:		December 2014
+KernelVersion:	3.19
+Contact:	Gabriele Mazzotta <gabriele.mzt@gmail.com>,
+		Pali Rohár <pali.rohar@gmail.com>
+Description:
+		This file allows to specifiy the on/off threshold value,
+		as reported by the ambient light sensor.
+
+What:		/sys/class/leds/dell::kbd_backlight/start_triggers
+Date:		December 2014
+KernelVersion:	3.19
+Contact:	Gabriele Mazzotta <gabriele.mzt@gmail.com>,
+		Pali Rohár <pali.rohar@gmail.com>
+Description:
+		This file allows to control the input triggers that
+		turn on the keyboard backlight illumination that is
+		disabled because of inactivity.
+		Read the file to see the triggers available. The ones
+		enabled are preceded by '+', those disabled by '-'.
+
+		To enable a trigger, write its name preceded by '+' to
+		this file. To disable a trigger, write its name preceded
+		by '-' instead.
+
+		For example, to enable the keyboard as trigger run:
+		    echo +keyboard > /sys/class/leds/dell::kbd_backlight/start_triggers
+		To disable it:
+		    echo -keyboard > /sys/class/leds/dell::kbd_backlight/start_triggers
+
+		Note that not all the available triggers can be configured.
+
+What:		/sys/class/leds/dell::kbd_backlight/stop_timeout
+Date:		December 2014
+KernelVersion:	3.19
+Contact:	Gabriele Mazzotta <gabriele.mzt@gmail.com>,
+		Pali Rohár <pali.rohar@gmail.com>
+Description:
+		This file allows to specify the interval after which the
+		keyboard illumination is disabled because of inactivity.
+		The timeouts are expressed in seconds, minutes, hours and
+		days, for which the symbols are 's', 'm', 'h' and 'd'
+		respectively.
+
+		To configure the timeout, write to this file a value along
+		with any the above units. If no unit is specified, the value
+		is assumed to be expressed in seconds.
+
+		For example, to set the timeout to 10 minutes run:
+		    echo 10m > /sys/class/leds/dell::kbd_backlight/stop_timeout
+
+		Note that when this file is read, the returned value might be
+		expressed in a different unit than the one used when the timeout
+		was set.
+
+		Also note that only some timeouts are supported and that
+		some systems might fall back to a specific timeout in case
+		an invalid timeout is written to this file.

drivers/platform/x86/dell-laptop.c

@@ -2,9 +2,11 @@
  *  Driver for Dell laptop extras
  *
  *  Copyright (c) Red Hat <mjg@redhat.com>
+ *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
+ *  Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
  *
- *  Based on documentation in the libsmbios package, Copyright (C) 2005 Dell
- *  Inc.
+ *  Based on documentation in the libsmbios package:
+ *  Copyright (C) 2005-2014 Dell Inc.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2 as
@@ -32,6 +34,13 @@
 #include "../../firmware/dcdbas.h"
 
 #define BRIGHTNESS_TOKEN 0x7d
+#define KBD_LED_OFF_TOKEN 0x01E1
+#define KBD_LED_ON_TOKEN 0x01E2
+#define KBD_LED_AUTO_TOKEN 0x01E3
+#define KBD_LED_AUTO_25_TOKEN 0x02EA
+#define KBD_LED_AUTO_50_TOKEN 0x02EB
+#define KBD_LED_AUTO_75_TOKEN 0x02EC
+#define KBD_LED_AUTO_100_TOKEN 0x02F6
 
 /* This structure will be modified by the firmware when we enter
  * system management mode, hence the volatiles */
@@ -62,6 +71,13 @@ struct calling_interface_structure {
 
 struct quirk_entry {
 	u8 touchpad_led;
+
+	int needs_kbd_timeouts;
+	/*
+	 * Ordered list of timeouts expressed in seconds.
+	 * The list must end with -1
+	 */
+	int kbd_timeouts[];
 };
 
 static struct quirk_entry *quirks;
@@ -76,6 +92,15 @@ static int __init dmi_matched(const struct dmi_system_id *dmi)
 	return 1;
 }
 
+/*
+ * These values come from Windows utility provided by Dell. If any other value
+ * is used then BIOS silently set timeout to 0 without any error message.
+ */
+static struct quirk_entry quirk_dell_xps13_9333 = {
+	.needs_kbd_timeouts = 1,
+	.kbd_timeouts = { 0, 5, 15, 60, 5 * 60, 15 * 60, -1 },
+};
+
 static int da_command_address;
 static int da_command_code;
 static int da_num_tokens;
@@ -267,6 +292,15 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
 		},
 		.driver_data = &quirk_dell_vostro_v130,
 	},
+	{
+		.callback = dmi_matched,
+		.ident = "Dell XPS13 9333",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "XPS13 9333"),
+		},
+		.driver_data = &quirk_dell_xps13_9333,
+	},
 	{ }
 };
 
@@ -331,17 +365,29 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy)
 	}
 }
 
-static int find_token_location(int tokenid)
+static int find_token_id(int tokenid)
 {
 	int i;
+
 	for (i = 0; i < da_num_tokens; i++) {
 		if (da_tokens[i].tokenID == tokenid)
-			return da_tokens[i].location;
+			return i;
 	}
 
 	return -1;
 }
 
+static int find_token_location(int tokenid)
+{
+	int id;
+
+	id = find_token_id(tokenid);
+	if (id == -1)
+		return -1;
+
+	return da_tokens[id].location;
+}
+
 static struct calling_interface_buffer *
 dell_send_request(struct calling_interface_buffer *buffer, int class,
 		  int select)
@@ -362,6 +408,20 @@ dell_send_request(struct calling_interface_buffer *buffer, int class,
 	return buffer;
 }
 
+static inline int dell_smi_error(int value)
+{
+	switch (value) {
+	case 0: /* Completed successfully */
+		return 0;
+	case -1: /* Completed with error */
+		return -EIO;
+	case -2: /* Function not supported */
+		return -ENXIO;
+	default: /* Unknown error */
+		return -EINVAL;
+	}
+}
+
 /* Derived from information in DellWirelessCtl.cpp:
    Class 17, select 11 is radio control. It returns an array of 32-bit values.
 
@@ -716,7 +776,7 @@ static int dell_send_intensity(struct backlight_device *bd)
 	else
 		dell_send_request(buffer, 1, 1);
 
-out:
+ out:
 	release_buffer();
 	return ret;
 }
@@ -740,7 +800,7 @@ static int dell_get_intensity(struct backlight_device *bd)
 
 	ret = buffer->output[1];
 
-out:
+ out:
 	release_buffer();
 	return ret;
 }
@@ -789,6 +849,1018 @@ static void touchpad_led_exit(void)
 	led_classdev_unregister(&touchpad_led);
 }
 
+/*
+ * Derived from information in smbios-keyboard-ctl:
+ *
+ * cbClass 4
+ * cbSelect 11
+ * Keyboard illumination
+ * cbArg1 determines the function to be performed
+ *
+ * cbArg1 0x0 = Get Feature Information
+ *  cbRES1         Standard return codes (0, -1, -2)
+ *  cbRES2, word0  Bitmap of user-selectable modes
+ *     bit 0     Always off (All systems)
+ *     bit 1     Always on (Travis ATG, Siberia)
+ *     bit 2     Auto: ALS-based On; ALS-based Off (Travis ATG)
+ *     bit 3     Auto: ALS- and input-activity-based On; input-activity based Off
+ *     bit 4     Auto: Input-activity-based On; input-activity based Off
+ *     bit 5     Auto: Input-activity-based On (illumination level 25%); input-activity based Off
+ *     bit 6     Auto: Input-activity-based On (illumination level 50%); input-activity based Off
+ *     bit 7     Auto: Input-activity-based On (illumination level 75%); input-activity based Off
+ *     bit 8     Auto: Input-activity-based On (illumination level 100%); input-activity based Off
+ *     bits 9-15 Reserved for future use
+ *  cbRES2, byte2  Reserved for future use
+ *  cbRES2, byte3  Keyboard illumination type
+ *     0         Reserved
+ *     1         Tasklight
+ *     2         Backlight
+ *     3-255     Reserved for future use
+ *  cbRES3, byte0  Supported auto keyboard illumination trigger bitmap.
+ *     bit 0     Any keystroke
+ *     bit 1     Touchpad activity
+ *     bit 2     Pointing stick
+ *     bit 3     Any mouse
+ *     bits 4-7  Reserved for future use
+ *  cbRES3, byte1  Supported timeout unit bitmap
+ *     bit 0     Seconds
+ *     bit 1     Minutes
+ *     bit 2     Hours
+ *     bit 3     Days
+ *     bits 4-7  Reserved for future use
+ *  cbRES3, byte2  Number of keyboard light brightness levels
+ *  cbRES4, byte0  Maximum acceptable seconds value (0 if seconds not supported).
+ *  cbRES4, byte1  Maximum acceptable minutes value (0 if minutes not supported).
+ *  cbRES4, byte2  Maximum acceptable hours value (0 if hours not supported).
+ *  cbRES4, byte3  Maximum acceptable days value (0 if days not supported)
+ *
+ * cbArg1 0x1 = Get Current State
+ *  cbRES1         Standard return codes (0, -1, -2)
+ *  cbRES2, word0  Bitmap of current mode state
+ *     bit 0     Always off (All systems)
+ *     bit 1     Always on (Travis ATG, Siberia)
+ *     bit 2     Auto: ALS-based On; ALS-based Off (Travis ATG)
+ *     bit 3     Auto: ALS- and input-activity-based On; input-activity based Off
+ *     bit 4     Auto: Input-activity-based On; input-activity based Off
+ *     bit 5     Auto: Input-activity-based On (illumination level 25%); input-activity based Off
+ *     bit 6     Auto: Input-activity-based On (illumination level 50%); input-activity based Off
+ *     bit 7     Auto: Input-activity-based On (illumination level 75%); input-activity based Off
+ *     bit 8     Auto: Input-activity-based On (illumination level 100%); input-activity based Off
+ *     bits 9-15 Reserved for future use
+ *     Note: Only One bit can be set
+ *  cbRES2, byte2  Currently active auto keyboard illumination triggers.
+ *     bit 0     Any keystroke
+ *     bit 1     Touchpad activity
+ *     bit 2     Pointing stick
+ *     bit 3     Any mouse
+ *     bits 4-7  Reserved for future use
+ *  cbRES2, byte3  Current Timeout
+ *     bits 7:6  Timeout units indicator:
+ *     00b       Seconds
+ *     01b       Minutes
+ *     10b       Hours
+ *     11b       Days
+ *     bits 5:0  Timeout value (0-63) in sec/min/hr/day
+ *     NOTE: A value of 0 means always on (no timeout) if any bits of RES3 byte
+ *     are set upon return from the [Get feature information] call.
+ *  cbRES3, byte0  Current setting of ALS value that turns the light on or off.
+ *  cbRES3, byte1  Current ALS reading
+ *  cbRES3, byte2  Current keyboard light level.
+ *
+ * cbArg1 0x2 = Set New State
+ *  cbRES1         Standard return codes (0, -1, -2)
+ *  cbArg2, word0  Bitmap of current mode state
+ *     bit 0     Always off (All systems)
+ *     bit 1     Always on (Travis ATG, Siberia)
+ *     bit 2     Auto: ALS-based On; ALS-based Off (Travis ATG)
+ *     bit 3     Auto: ALS- and input-activity-based On; input-activity based Off
+ *     bit 4     Auto: Input-activity-based On; input-activity based Off
+ *     bit 5     Auto: Input-activity-based On (illumination level 25%); input-activity based Off
+ *     bit 6     Auto: Input-activity-based On (illumination level 50%); input-activity based Off
+ *     bit 7     Auto: Input-activity-based On (illumination level 75%); input-activity based Off
+ *     bit 8     Auto: Input-activity-based On (illumination level 100%); input-activity based Off
+ *     bits 9-15 Reserved for future use
+ *     Note: Only One bit can be set
+ *  cbArg2, byte2  Desired auto keyboard illumination triggers. Must remain inactive to allow
+ *                 keyboard to turn off automatically.
+ *     bit 0     Any keystroke
+ *     bit 1     Touchpad activity
+ *     bit 2     Pointing stick
+ *     bit 3     Any mouse
+ *     bits 4-7  Reserved for future use
+ *  cbArg2, byte3  Desired Timeout
+ *     bits 7:6  Timeout units indicator:
+ *     00b       Seconds
+ *     01b       Minutes
+ *     10b       Hours
+ *     11b       Days
+ *     bits 5:0  Timeout value (0-63) in sec/min/hr/day
+ *  cbArg3, byte0  Desired setting of ALS value that turns the light on or off.
+ *  cbArg3, byte2  Desired keyboard light level.
+ */
+
+
+enum kbd_timeout_unit {
+	KBD_TIMEOUT_SECONDS = 0,
+	KBD_TIMEOUT_MINUTES,
+	KBD_TIMEOUT_HOURS,
+	KBD_TIMEOUT_DAYS,
+};
+
+enum kbd_mode_bit {
+	KBD_MODE_BIT_OFF = 0,
+	KBD_MODE_BIT_ON,
+	KBD_MODE_BIT_ALS,
+	KBD_MODE_BIT_TRIGGER_ALS,
+	KBD_MODE_BIT_TRIGGER,
+	KBD_MODE_BIT_TRIGGER_25,
+	KBD_MODE_BIT_TRIGGER_50,
+	KBD_MODE_BIT_TRIGGER_75,
+	KBD_MODE_BIT_TRIGGER_100,
+};
+
+#define kbd_is_als_mode_bit(bit) \
+	((bit) == KBD_MODE_BIT_ALS || (bit) == KBD_MODE_BIT_TRIGGER_ALS)
+#define kbd_is_trigger_mode_bit(bit) \
+	((bit) >= KBD_MODE_BIT_TRIGGER_ALS && (bit) <= KBD_MODE_BIT_TRIGGER_100)
+#define kbd_is_level_mode_bit(bit) \
+	((bit) >= KBD_MODE_BIT_TRIGGER_25 && (bit) <= KBD_MODE_BIT_TRIGGER_100)
+
+struct kbd_info {
+	u16 modes;
+	u8 type;
+	u8 triggers;
+	u8 levels;
+	u8 seconds;
+	u8 minutes;
+	u8 hours;
+	u8 days;
+};
+
+struct kbd_state {
+	u8 mode_bit;
+	u8 triggers;
+	u8 timeout_value;
+	u8 timeout_unit;
+	u8 als_setting;
+	u8 als_value;
+	u8 level;
+};
+
+static const int kbd_tokens[] = {
+	KBD_LED_OFF_TOKEN,
+	KBD_LED_AUTO_25_TOKEN,
+	KBD_LED_AUTO_50_TOKEN,
+	KBD_LED_AUTO_75_TOKEN,
+	KBD_LED_AUTO_100_TOKEN,
+	KBD_LED_ON_TOKEN,
+};
+
+static u16 kbd_token_bits;
+
+static struct kbd_info kbd_info;
+static bool kbd_als_supported;
+static bool kbd_triggers_supported;
+
+static u8 kbd_mode_levels[16];
+static int kbd_mode_levels_count;
+
+static u8 kbd_previous_level;
+static u8 kbd_previous_mode_bit;
+
+static bool kbd_led_present;
+
+/*
+ * NOTE: there are three ways to set the keyboard backlight level.
+ * First, via kbd_state.mode_bit (assigning KBD_MODE_BIT_TRIGGER_* value).
+ * Second, via kbd_state.level (assigning numerical value <= kbd_info.levels).
+ * Third, via SMBIOS tokens (KBD_LED_* in kbd_tokens)
+ *
+ * There are laptops which support only one of these methods. If we want to
+ * support as many machines as possible we need to implement all three methods.
+ * The first two methods use the kbd_state structure. The third uses SMBIOS
+ * tokens. If kbd_info.levels == 0, the machine does not support setting the
+ * keyboard backlight level via kbd_state.level.
+ */
+
+static int kbd_get_info(struct kbd_info *info)
+{
+	u8 units;
+	int ret;
+
+	get_buffer();
+
+	buffer->input[0] = 0x0;
+	dell_send_request(buffer, 4, 11);
+	ret = buffer->output[0];
+
+	if (ret) {
+		ret = dell_smi_error(ret);
+		goto out;
+	}
+
+	info->modes = buffer->output[1] & 0xFFFF;
+	info->type = (buffer->output[1] >> 24) & 0xFF;
+	info->triggers = buffer->output[2] & 0xFF;
+	units = (buffer->output[2] >> 8) & 0xFF;
+	info->levels = (buffer->output[2] >> 16) & 0xFF;
+
+	if (units & BIT(0))
+		info->seconds = (buffer->output[3] >> 0) & 0xFF;
+	if (units & BIT(1))
+		info->minutes = (buffer->output[3] >> 8) & 0xFF;
+	if (units & BIT(2))
+		info->hours = (buffer->output[3] >> 16) & 0xFF;
+	if (units & BIT(3))
+		info->days = (buffer->output[3] >> 24) & 0xFF;
+
+ out:
+	release_buffer();
+	return ret;
+}
+
+static unsigned int kbd_get_max_level(void)
+{
+	if (kbd_info.levels != 0)
+		return kbd_info.levels;
+	if (kbd_mode_levels_count > 0)
+		return kbd_mode_levels_count - 1;
+	return 0;
+}
+
+static int kbd_get_level(struct kbd_state *state)
+{
+	int i;
+
+	if (kbd_info.levels != 0)
+		return state->level;
+
+	if (kbd_mode_levels_count > 0) {
+		for (i = 0; i < kbd_mode_levels_count; ++i)
+			if (kbd_mode_levels[i] == state->mode_bit)
+				return i;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int kbd_set_level(struct kbd_state *state, u8 level)
+{
+	if (kbd_info.levels != 0) {
+		if (level != 0)
+			kbd_previous_level = level;
+		if (state->level == level)
+			return 0;
+		state->level = level;
+		if (level != 0 && state->mode_bit == KBD_MODE_BIT_OFF)
+			state->mode_bit = kbd_previous_mode_bit;
+		else if (level == 0 && state->mode_bit != KBD_MODE_BIT_OFF) {
+			kbd_previous_mode_bit = state->mode_bit;
+			state->mode_bit = KBD_MODE_BIT_OFF;
+		}
+		return 0;
+	}
+
+	if (kbd_mode_levels_count > 0 && level < kbd_mode_levels_count) {
+		if (level != 0)
+			kbd_previous_level = level;
+		state->mode_bit = kbd_mode_levels[level];
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int kbd_get_state(struct kbd_state *state)
+{
+	int ret;
+
+	get_buffer();
+
+	buffer->input[0] = 0x1;
+	dell_send_request(buffer, 4, 11);
+	ret = buffer->output[0];
+
+	if (ret) {
+		ret = dell_smi_error(ret);
+		goto out;
+	}
+
+	state->mode_bit = ffs(buffer->output[1] & 0xFFFF);
+	if (state->mode_bit != 0)
+		state->mode_bit--;
+
+	state->triggers = (buffer->output[1] >> 16) & 0xFF;
+	state->timeout_value = (buffer->output[1] >> 24) & 0x3F;
+	state->timeout_unit = (buffer->output[1] >> 30) & 0x3;
+	state->als_setting = buffer->output[2] & 0xFF;
+	state->als_value = (buffer->output[2] >> 8) & 0xFF;
+	state->level = (buffer->output[2] >> 16) & 0xFF;
+
+ out:
+	release_buffer();
+	return ret;
+}
+
+static int kbd_set_state(struct kbd_state *state)
+{
+	int ret;
+
+	get_buffer();
+	buffer->input[0] = 0x2;
+	buffer->input[1] = BIT(state->mode_bit) & 0xFFFF;
+	buffer->input[1] |= (state->triggers & 0xFF) << 16;
+	buffer->input[1] |= (state->timeout_value & 0x3F) << 24;
+	buffer->input[1] |= (state->timeout_unit & 0x3) << 30;
+	buffer->input[2] = state->als_setting & 0xFF;
+	buffer->input[2] |= (state->level & 0xFF) << 16;
+	dell_send_request(buffer, 4, 11);
+	ret = buffer->output[0];
+	release_buffer();
+
+	return dell_smi_error(ret);
+}
+
+static int kbd_set_state_safe(struct kbd_state *state, struct kbd_state *old)
+{
+	int ret;
+
+	ret = kbd_set_state(state);
+	if (ret == 0)
+		return 0;
+
+	/*
+	 * When setting the new state fails,try to restore the previous one.
+	 * This is needed on some machines where BIOS sets a default state when
+	 * setting a new state fails. This default state could be all off.
+	 */
+
+	if (kbd_set_state(old))
+		pr_err("Setting old previous keyboard state failed\n");
+
+	return ret;
+}
+
+static int kbd_set_token_bit(u8 bit)
+{
+	int id;
+	int ret;
+
+	if (bit >= ARRAY_SIZE(kbd_tokens))
+		return -EINVAL;
+
+	id = find_token_id(kbd_tokens[bit]);
+	if (id == -1)
+		return -EINVAL;
+
+	get_buffer();
+	buffer->input[0] = da_tokens[id].location;
+	buffer->input[1] = da_tokens[id].value;
+	dell_send_request(buffer, 1, 0);
+	ret = buffer->output[0];
+	release_buffer();
+
+	return dell_smi_error(ret);
+}
+
+static int kbd_get_token_bit(u8 bit)
+{
+	int id;
+	int ret;
+	int val;
+
+	if (bit >= ARRAY_SIZE(kbd_tokens))
+		return -EINVAL;
+
+	id = find_token_id(kbd_tokens[bit]);
+	if (id == -1)
+		return -EINVAL;
+
+	get_buffer();
+	buffer->input[0] = da_tokens[id].location;
+	dell_send_request(buffer, 0, 0);
+	ret = buffer->output[0];
+	val = buffer->output[1];
+	release_buffer();
+
+	if (ret)
+		return dell_smi_error(ret);
+
+	return (val == da_tokens[id].value);
+}
+
+static int kbd_get_first_active_token_bit(void)
+{
+	int i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(kbd_tokens); ++i) {
+		ret = kbd_get_token_bit(i);
+		if (ret == 1)
+			return i;
+	}
+
+	return ret;
+}
+
+static int kbd_get_valid_token_counts(void)
+{
+	return hweight16(kbd_token_bits);
+}
+
+static inline int kbd_init_info(void)
+{
+	struct kbd_state state;
+	int ret;
+	int i;
+
+	ret = kbd_get_info(&kbd_info);
+	if (ret)
+		return ret;
+
+	kbd_get_state(&state);
+
+	/* NOTE: timeout value is stored in 6 bits so max value is 63 */
+	if (kbd_info.seconds > 63)
+		kbd_info.seconds = 63;
+	if (kbd_info.minutes > 63)
+		kbd_info.minutes = 63;
+	if (kbd_info.hours > 63)
+		kbd_info.hours = 63;
+	if (kbd_info.days > 63)
+		kbd_info.days = 63;
+
+	/* NOTE: On tested machines ON mode did not work and caused
+	 *       problems (turned backlight off) so do not use it
+	 */
+	kbd_info.modes &= ~BIT(KBD_MODE_BIT_ON);
+
+	kbd_previous_level = kbd_get_level(&state);
+	kbd_previous_mode_bit = state.mode_bit;
+
+	if (kbd_previous_level == 0 && kbd_get_max_level() != 0)
+		kbd_previous_level = 1;
+
+	if (kbd_previous_mode_bit == KBD_MODE_BIT_OFF) {
+		kbd_previous_mode_bit =
+			ffs(kbd_info.modes & ~BIT(KBD_MODE_BIT_OFF));
+		if (kbd_previous_mode_bit != 0)
+			kbd_previous_mode_bit--;
+	}
+
+	if (kbd_info.modes & (BIT(KBD_MODE_BIT_ALS) |
+			      BIT(KBD_MODE_BIT_TRIGGER_ALS)))
+		kbd_als_supported = true;
+
+	if (kbd_info.modes & (
+	    BIT(KBD_MODE_BIT_TRIGGER_ALS) | BIT(KBD_MODE_BIT_TRIGGER) |
+	    BIT(KBD_MODE_BIT_TRIGGER_25) | BIT(KBD_MODE_BIT_TRIGGER_50) |
+	    BIT(KBD_MODE_BIT_TRIGGER_75) | BIT(KBD_MODE_BIT_TRIGGER_100)
+	   ))
+		kbd_triggers_supported = true;
+
+	/* kbd_mode_levels[0] is reserved, see below */
+	for (i = 0; i < 16; ++i)
+		if (kbd_is_level_mode_bit(i) && (BIT(i) & kbd_info.modes))
+			kbd_mode_levels[1 + kbd_mode_levels_count++] = i;
+
+	/*
+	 * Find the first supported mode and assign to kbd_mode_levels[0].
+	 * This should be 0 (off), but we cannot depend on the BIOS to
+	 * support 0.
+	 */
+	if (kbd_mode_levels_count > 0) {
+		for (i = 0; i < 16; ++i) {
+			if (BIT(i) & kbd_info.modes) {
+				kbd_mode_levels[0] = i;
+				break;
+			}
+		}
+		kbd_mode_levels_count++;
+	}
+
+	return 0;
+
+}
+
+static inline void kbd_init_tokens(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(kbd_tokens); ++i)
+		if (find_token_id(kbd_tokens[i]) != -1)
+			kbd_token_bits |= BIT(i);
+}
+
+static void kbd_init(void)
+{
+	int ret;
+
+	ret = kbd_init_info();
+	kbd_init_tokens();
+
+	if (kbd_token_bits != 0 || ret == 0)
+		kbd_led_present = true;
+}
+
+static ssize_t kbd_led_timeout_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct kbd_state new_state;
+	struct kbd_state state;
+	bool convert;
+	int value;
+	int ret;
+	char ch;
+	u8 unit;
+	int i;
+
+	ret = sscanf(buf, "%d %c", &value, &ch);
+	if (ret < 1)
+		return -EINVAL;
+	else if (ret == 1)
+		ch = 's';
+
+	if (value < 0)
+		return -EINVAL;
+
+	convert = false;
+
+	switch (ch) {
+	case 's':
+		if (value > kbd_info.seconds)
+			convert = true;
+		unit = KBD_TIMEOUT_SECONDS;
+		break;
+	case 'm':
+		if (value > kbd_info.minutes)
+			convert = true;
+		unit = KBD_TIMEOUT_MINUTES;
+		break;
+	case 'h':
+		if (value > kbd_info.hours)
+			convert = true;
+		unit = KBD_TIMEOUT_HOURS;
+		break;
+	case 'd':
+		if (value > kbd_info.days)
+			convert = true;
+		unit = KBD_TIMEOUT_DAYS;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (quirks && quirks->needs_kbd_timeouts)
+		convert = true;
+
+	if (convert) {
+		/* Convert value from current units to seconds */
+		switch (unit) {
+		case KBD_TIMEOUT_DAYS:
+			value *= 24;
+		case KBD_TIMEOUT_HOURS:
+			value *= 60;
+		case KBD_TIMEOUT_MINUTES:
+			value *= 60;
+			unit = KBD_TIMEOUT_SECONDS;
+		}
+
+		if (quirks && quirks->needs_kbd_timeouts) {
+			for (i = 0; quirks->kbd_timeouts[i] != -1; i++) {
+				if (value <= quirks->kbd_timeouts[i]) {
+					value = quirks->kbd_timeouts[i];
+					break;
+				}
+			}
+		}
+
+		if (value <= kbd_info.seconds && kbd_info.seconds) {
+			unit = KBD_TIMEOUT_SECONDS;
+		} else if (value / 60 <= kbd_info.minutes && kbd_info.minutes) {
+			value /= 60;
+			unit = KBD_TIMEOUT_MINUTES;
+		} else if (value / (60 * 60) <= kbd_info.hours && kbd_info.hours) {
+			value /= (60 * 60);
+			unit = KBD_TIMEOUT_HOURS;
+		} else if (value / (60 * 60 * 24) <= kbd_info.days && kbd_info.days) {
+			value /= (60 * 60 * 24);
+			unit = KBD_TIMEOUT_DAYS;
+		} else {
+			return -EINVAL;
+		}
+	}
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	new_state = state;
+	new_state.timeout_value = value;
+	new_state.timeout_unit = unit;
+
+	ret = kbd_set_state_safe(&new_state, &state);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t kbd_led_timeout_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct kbd_state state;
+	int ret;
+	int len;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	len = sprintf(buf, "%d", state.timeout_value);
+
+	switch (state.timeout_unit) {
+	case KBD_TIMEOUT_SECONDS:
+		return len + sprintf(buf+len, "s\n");
+	case KBD_TIMEOUT_MINUTES:
+		return len + sprintf(buf+len, "m\n");
+	case KBD_TIMEOUT_HOURS:
+		return len + sprintf(buf+len, "h\n");
+	case KBD_TIMEOUT_DAYS:
+		return len + sprintf(buf+len, "d\n");
+	default:
+		return -EINVAL;
+	}
+
+	return len;
+}
+
+static DEVICE_ATTR(stop_timeout, S_IRUGO | S_IWUSR,
+		   kbd_led_timeout_show, kbd_led_timeout_store);
+
+static const char * const kbd_led_triggers[] = {
+	"keyboard",
+	"touchpad",
+	/*"trackstick"*/ NULL, /* NOTE: trackstick is just alias for touchpad */
+	"mouse",
+};
+
+static ssize_t kbd_led_triggers_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct kbd_state new_state;
+	struct kbd_state state;
+	bool triggers_enabled = false;
+	int trigger_bit = -1;
+	char trigger[21];
+	int i, ret;
+
+	ret = sscanf(buf, "%20s", trigger);
+	if (ret != 1)
+		return -EINVAL;
+
+	if (trigger[0] != '+' && trigger[0] != '-')
+		return -EINVAL;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	if (kbd_triggers_supported)
+		triggers_enabled = kbd_is_trigger_mode_bit(state.mode_bit);
+
+	if (kbd_triggers_supported) {
+		for (i = 0; i < ARRAY_SIZE(kbd_led_triggers); ++i) {
+			if (!(kbd_info.triggers & BIT(i)))
+				continue;
+			if (!kbd_led_triggers[i])
+				continue;
+			if (strcmp(trigger+1, kbd_led_triggers[i]) != 0)
+				continue;
+			if (trigger[0] == '+' &&
+			    triggers_enabled && (state.triggers & BIT(i)))
+				return count;
+			if (trigger[0] == '-' &&
+			    (!triggers_enabled || !(state.triggers & BIT(i))))
+				return count;
+			trigger_bit = i;
+			break;
+		}
+	}
+
+	if (trigger_bit != -1) {
+		new_state = state;
+		if (trigger[0] == '+')
+			new_state.triggers |= BIT(trigger_bit);
+		else {
+			new_state.triggers &= ~BIT(trigger_bit);
+			/* NOTE: trackstick bit (2) must be disabled when
+			 *       disabling touchpad bit (1), otherwise touchpad
+			 *       bit (1) will not be disabled */
+			if (trigger_bit == 1)
+				new_state.triggers &= ~BIT(2);
+		}
+		if ((kbd_info.triggers & new_state.triggers) !=
+		    new_state.triggers)
+			return -EINVAL;
+		if (new_state.triggers && !triggers_enabled) {
+			new_state.mode_bit = KBD_MODE_BIT_TRIGGER;
+			kbd_set_level(&new_state, kbd_previous_level);
+		} else if (new_state.triggers == 0) {
+			kbd_set_level(&new_state, 0);
+		}
+		if (!(kbd_info.modes & BIT(new_state.mode_bit)))
+			return -EINVAL;
+		ret = kbd_set_state_safe(&new_state, &state);
+		if (ret)
+			return ret;
+		if (new_state.mode_bit != KBD_MODE_BIT_OFF)
+			kbd_previous_mode_bit = new_state.mode_bit;
+		return count;
+	}
+
+	return -EINVAL;
+}
+
+static ssize_t kbd_led_triggers_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct kbd_state state;
+	bool triggers_enabled;
+	int level, i, ret;
+	int len = 0;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	len = 0;
+
+	if (kbd_triggers_supported) {
+		triggers_enabled = kbd_is_trigger_mode_bit(state.mode_bit);
+		level = kbd_get_level(&state);
+		for (i = 0; i < ARRAY_SIZE(kbd_led_triggers); ++i) {
+			if (!(kbd_info.triggers & BIT(i)))
+				continue;
+			if (!kbd_led_triggers[i])
+				continue;
+			if ((triggers_enabled || level <= 0) &&
+			    (state.triggers & BIT(i)))
+				buf[len++] = '+';
+			else
+				buf[len++] = '-';
+			len += sprintf(buf+len, "%s ", kbd_led_triggers[i]);
+		}
+	}
+
+	if (len)
+		buf[len - 1] = '\n';
+
+	return len;
+}
+
+static DEVICE_ATTR(start_triggers, S_IRUGO | S_IWUSR,
+		   kbd_led_triggers_show, kbd_led_triggers_store);
+
+static ssize_t kbd_led_als_enabled_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct kbd_state new_state;
+	struct kbd_state state;
+	bool triggers_enabled = false;
+	int enable;
+	int ret;
+
+	ret = kstrtoint(buf, 0, &enable);
+	if (ret)
+		return ret;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	if (enable == kbd_is_als_mode_bit(state.mode_bit))
+		return count;
+
+	new_state = state;
+
+	if (kbd_triggers_supported)
+		triggers_enabled = kbd_is_trigger_mode_bit(state.mode_bit);
+
+	if (enable) {
+		if (triggers_enabled)
+			new_state.mode_bit = KBD_MODE_BIT_TRIGGER_ALS;
+		else
+			new_state.mode_bit = KBD_MODE_BIT_ALS;
+	} else {
+		if (triggers_enabled) {
+			new_state.mode_bit = KBD_MODE_BIT_TRIGGER;
+			kbd_set_level(&new_state, kbd_previous_level);
+		} else {
+			new_state.mode_bit = KBD_MODE_BIT_ON;
+		}
+	}
+	if (!(kbd_info.modes & BIT(new_state.mode_bit)))
+		return -EINVAL;
+
+	ret = kbd_set_state_safe(&new_state, &state);
+	if (ret)
+		return ret;
+	kbd_previous_mode_bit = new_state.mode_bit;
+
+	return count;
+}
+
+static ssize_t kbd_led_als_enabled_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct kbd_state state;
+	bool enabled = false;
+	int ret;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+	enabled = kbd_is_als_mode_bit(state.mode_bit);
+
+	return sprintf(buf, "%d\n", enabled ? 1 : 0);
+}
+
+static DEVICE_ATTR(als_enabled, S_IRUGO | S_IWUSR,
+		   kbd_led_als_enabled_show, kbd_led_als_enabled_store);
+
+static ssize_t kbd_led_als_setting_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct kbd_state state;
+	struct kbd_state new_state;
+	u8 setting;
+	int ret;
+
+	ret = kstrtou8(buf, 10, &setting);
+	if (ret)
+		return ret;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	new_state = state;
+	new_state.als_setting = setting;
+
+	ret = kbd_set_state_safe(&new_state, &state);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t kbd_led_als_setting_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct kbd_state state;
+	int ret;
+
+	ret = kbd_get_state(&state);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%d\n", state.als_setting);
+}
+
+static DEVICE_ATTR(als_setting, S_IRUGO | S_IWUSR,
+		   kbd_led_als_setting_show, kbd_led_als_setting_store);
+
+static struct attribute *kbd_led_attrs[] = {
+	&dev_attr_stop_timeout.attr,
+	&dev_attr_start_triggers.attr,
+	NULL,
+};
+
+static const struct attribute_group kbd_led_group = {
+	.attrs = kbd_led_attrs,
+};
+
+static struct attribute *kbd_led_als_attrs[] = {
+	&dev_attr_als_enabled.attr,
+	&dev_attr_als_setting.attr,
+	NULL,
+};
+
+static const struct attribute_group kbd_led_als_group = {
+	.attrs = kbd_led_als_attrs,
+};
+
+static const struct attribute_group *kbd_led_groups[] = {
+	&kbd_led_group,
+	&kbd_led_als_group,
+	NULL,
+};
+
+static enum led_brightness kbd_led_level_get(struct led_classdev *led_cdev)
+{
+	int ret;
+	u16 num;
+	struct kbd_state state;
+
+	if (kbd_get_max_level()) {
+		ret = kbd_get_state(&state);
+		if (ret)
+			return 0;
+		ret = kbd_get_level(&state);
+		if (ret < 0)
+			return 0;
+		return ret;
+	}
+
+	if (kbd_get_valid_token_counts()) {
+		ret = kbd_get_first_active_token_bit();
+		if (ret < 0)
+			return 0;
+		for (num = kbd_token_bits; num != 0 && ret > 0; --ret)
+			num &= num - 1; /* clear the first bit set */
+		if (num == 0)
+			return 0;
+		return ffs(num) - 1;
+	}
+
+	pr_warn("Keyboard brightness level control not supported\n");
+	return 0;
+}
+
+static void kbd_led_level_set(struct led_classdev *led_cdev,
+			      enum led_brightness value)
+{
+	struct kbd_state state;
+	struct kbd_state new_state;
+	u16 num;
+
+	if (kbd_get_max_level()) {
+		if (kbd_get_state(&state))
+			return;
+		new_state = state;
+		if (kbd_set_level(&new_state, value))
+			return;
+		kbd_set_state_safe(&new_state, &state);
+		return;
+	}
+
+	if (kbd_get_valid_token_counts()) {
+		for (num = kbd_token_bits; num != 0 && value > 0; --value)
+			num &= num - 1; /* clear the first bit set */
+		if (num == 0)
+			return;
+		kbd_set_token_bit(ffs(num) - 1);
+		return;
+	}
+
+	pr_warn("Keyboard brightness level control not supported\n");
+}
+
+static struct led_classdev kbd_led = {
+	.name           = "dell::kbd_backlight",
+	.brightness_set = kbd_led_level_set,
+	.brightness_get = kbd_led_level_get,
+	.groups         = kbd_led_groups,
+};
+
+static int __init kbd_led_init(struct device *dev)
+{
+	kbd_init();
+	if (!kbd_led_present)
+		return -ENODEV;
+	if (!kbd_als_supported)
+		kbd_led_groups[1] = NULL;
+	kbd_led.max_brightness = kbd_get_max_level();
+	if (!kbd_led.max_brightness) {
+		kbd_led.max_brightness = kbd_get_valid_token_counts();
+		if (kbd_led.max_brightness)
+			kbd_led.max_brightness--;
+	}
+	return led_classdev_register(dev, &kbd_led);
+}
+
+static void brightness_set_exit(struct led_classdev *led_cdev,
+				enum led_brightness value)
+{
+	/* Don't change backlight level on exit */
+};
+
+static void kbd_led_exit(void)
+{
+	if (!kbd_led_present)
+		return;
+	kbd_led.brightness_set = brightness_set_exit;
+	led_classdev_unregister(&kbd_led);
+}
+
 static int __init dell_init(void)
 {
 	int max_intensity = 0;
@@ -841,6 +1913,8 @@ static int __init dell_init(void)
 	if (quirks && quirks->touchpad_led)
 		touchpad_led_init(&platform_device->dev);
 
+	kbd_led_init(&platform_device->dev);
+
 	dell_laptop_dir = debugfs_create_dir("dell_laptop", NULL);
 	if (dell_laptop_dir != NULL)
 		debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
@@ -908,6 +1982,7 @@ static void __exit dell_exit(void)
 	debugfs_remove_recursive(dell_laptop_dir);
 	if (quirks && quirks->touchpad_led)
 		touchpad_led_exit();
+	kbd_led_exit();
 	i8042_remove_filter(dell_laptop_i8042_filter);
 	cancel_delayed_work_sync(&dell_rfkill_work);
 	backlight_device_unregister(dell_backlight_device);
@@ -924,5 +1999,7 @@ module_init(dell_init);
 module_exit(dell_exit);
 
 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
+MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
+MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 MODULE_DESCRIPTION("Dell laptop driver");
 MODULE_LICENSE("GPL");