[PATCH v2] platform/x86: hp-wmi: Support omen backlight control wmi-acpi methods

[Rishit Bansal <rishitbansal0@gmail.com>]

The HP Omen Command Studio application includes a Light Studio feature
which can be used to control various features related to the keyboard
backlight via the 0x20009 command.

The command supports the following queries:

- 0x1: Checks if keyboard lighting is supported
- 0x2: Get the zone colors of each of the 4 zones on the keyboard
- 0x3: Set the zone colors of each of the 4 zones on the keyboard
- 0x4: Gets the state (on/off) of the backlight
- 0x5: Sets the state (on/off) of the backlight

This patch introduces a new sysfs led class called
"hp_omen::kbd_backlight" which can be used to control the state of the
backlight. It also includes a sysfs RW attribute called "kbd_rgb"
which can be used to get/set the current color of each zone.

Additionally, it also maps the backlight event to the KEY_KBDILLUMTOGGLE
key so it shows the correct notification on userspace.

The patch has been tested on an HP Omen 15-en0037AX (AMD) laptop.

Signed-off-by: Rishit Bansal <rishitbansal0@gmail.com>
---
Changes since v1:
 - Map backlight key to KEY_KBDILLUMTOGGLE
---
 drivers/platform/x86/hp/hp-wmi.c | 113 +++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)

diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index 0a99058be813..a9e2634a9d46 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -27,6 +27,7 @@
 #include <linux/rfkill.h>
 #include <linux/string.h>
 #include <linux/dmi.h>
+#include <linux/leds.h>
 
 MODULE_AUTHOR("Matthew Garrett <mjg59@srcf.ucam.org>");
 MODULE_DESCRIPTION("HP laptop WMI hotkeys driver");
@@ -136,6 +137,7 @@ enum hp_wmi_command {
 	HPWMI_WRITE	= 0x02,
 	HPWMI_ODM	= 0x03,
 	HPWMI_GM	= 0x20008,
+	HPWMI_KB    = 0x20009,
 };
 
 enum hp_wmi_hardware_mask {
@@ -219,6 +221,7 @@ static const struct key_entry hp_wmi_keymap[] = {
 	{ KE_KEY, 0x21a9,  { KEY_TOUCHPAD_OFF } },
 	{ KE_KEY, 0x121a9, { KEY_TOUCHPAD_ON } },
 	{ KE_KEY, 0x231b,  { KEY_HELP } },
+	{ KE_KEY, KEY_KBDILLUMTOGGLE, { KEY_KBDILLUMTOGGLE }},
 	{ KE_END, 0 }
 };
 
@@ -734,12 +737,56 @@ static ssize_t postcode_store(struct device *dev, struct device_attribute *attr,
 	return count;
 }
 
+static ssize_t kbd_rgb_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	u8 val[128];
+
+	int ret = hp_wmi_perform_query(HPWMI_HDDTEMP_QUERY, HPWMI_KB, &val,
+				       zero_if_sup(val), sizeof(val));
+
+	if (ret)
+		return ret;
+
+	strncat(buf, &val[25], 12);
+
+	return strlen(buf);
+}
+
+static ssize_t kbd_rgb_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	u8 val[128];
+	int ret;
+
+	ret = hp_wmi_perform_query(HPWMI_HDDTEMP_QUERY, HPWMI_KB, &val,
+				   zero_if_sup(val), sizeof(val));
+
+	if (ret)
+		return ret;
+
+	if (count != 12)
+		return -1;
+
+	strncpy(&val[25], buf, count);
+
+	ret = hp_wmi_perform_query(HPWMI_ALS_QUERY, HPWMI_KB, &val, sizeof(val),
+				   0);
+
+	if (ret)
+		return ret;
+
+	return count;
+}
+
 static DEVICE_ATTR_RO(display);
 static DEVICE_ATTR_RO(hddtemp);
 static DEVICE_ATTR_RW(als);
 static DEVICE_ATTR_RO(dock);
 static DEVICE_ATTR_RO(tablet);
 static DEVICE_ATTR_RW(postcode);
+static DEVICE_ATTR_RW(kbd_rgb);
 
 static struct attribute *hp_wmi_attrs[] = {
 	&dev_attr_display.attr,
@@ -748,6 +795,7 @@ static struct attribute *hp_wmi_attrs[] = {
 	&dev_attr_dock.attr,
 	&dev_attr_tablet.attr,
 	&dev_attr_postcode.attr,
+	&dev_attr_kbd_rgb.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(hp_wmi);
@@ -853,6 +901,8 @@ static void hp_wmi_notify(u32 value, void *context)
 	case HPWMI_PROXIMITY_SENSOR:
 		break;
 	case HPWMI_BACKLIT_KB_BRIGHTNESS:
+		sparse_keymap_report_event(hp_wmi_input_dev,
+						KEY_KBDILLUMTOGGLE, 1, true);
 		break;
 	case HPWMI_PEAKSHIFT_PERIOD:
 		break;
@@ -1294,6 +1344,63 @@ static int thermal_profile_setup(void)
 
 static int hp_wmi_hwmon_init(void);
 
+static struct led_classdev omen_kbd_led;
+
+static enum led_brightness get_omen_backlight_brightness(struct led_classdev *cdev)
+{
+	u8 val;
+
+	int ret = hp_wmi_perform_query(HPWMI_HARDWARE_QUERY, HPWMI_KB, &val, zero_if_sup(val), sizeof(val));
+
+	if (ret)
+		return ret;
+
+	return (val & 0x80) ? LED_ON : LED_OFF;
+}
+
+static void set_omen_backlight_brightness(struct led_classdev *cdev, enum led_brightness value)
+{
+	char buffer[4] = { (value == LED_OFF) ? 0x64 : 0xe4, 0, 0, 0 };
+
+	hp_wmi_perform_query(HPWMI_WIRELESS_QUERY, HPWMI_KB, &buffer,
+				       sizeof(buffer), 0);
+}
+
+
+static bool is_omen_lighting_supported(void)
+{
+	u8 val;
+
+	int ret = hp_wmi_perform_query(HPWMI_DISPLAY_QUERY, HPWMI_KB, &val, zero_if_sup(val), sizeof(val));
+
+	if (ret)
+		return false;
+
+	return (val & 1) == 1;
+}
+
+static int omen_backlight_init(struct device *dev)
+{
+	int ret;
+
+	omen_kbd_led.name = "hp_omen::kbd_backlight";
+	omen_kbd_led.brightness_set = set_omen_backlight_brightness;
+	omen_kbd_led.brightness_get = get_omen_backlight_brightness;
+	omen_kbd_led.max_brightness = 1;
+
+	ret = devm_led_classdev_register(dev, &omen_kbd_led);
+
+	if (ret < 0)
+		return -1;
+
+	return 0;
+}
+
+static void omen_backlight_exit(struct device *dev)
+{
+	devm_led_classdev_unregister(dev, &omen_kbd_led);
+}
+
 static int __init hp_wmi_bios_setup(struct platform_device *device)
 {
 	int err;
@@ -1321,6 +1428,9 @@ static int __init hp_wmi_bios_setup(struct platform_device *device)
 
 	thermal_profile_setup();
 
+	if (is_omen_lighting_supported())
+		omen_backlight_init(&device->dev);
+
 	return 0;
 }
 
@@ -1349,6 +1459,9 @@ static int __exit hp_wmi_bios_remove(struct platform_device *device)
 	if (platform_profile_support)
 		platform_profile_remove();
 
+	if (is_omen_lighting_supported())
+		omen_backlight_exit(&device->dev);
+
 	return 0;
 }
 
-- 
2.37.2