asus-wireless: Toggle airplane mode LED

In the ASHS device we have the HSWC method, which calls either OWGD or
OWGS, depending on its parameter:

	Device (ASHS)
	{
		Name (_HID, "ATK4002")  // _HID: Hardware ID
		Method (HSWC, 1, Serialized)
		{
			If ((Arg0 < 0x02))
			{
				OWGD (Arg0)
				Return (One)
			}
			If ((Arg0 == 0x02))
			{
				Local0 = OWGS ()
				If (Local0)
				{
					Return (0x05)
				}
				Else
				{
					Return (0x04)
				}
			}
			If ((Arg0 == 0x03))
			{
				Return (0xFF)
			}
			If ((Arg0 == 0x04))
			{
				OWGD (Zero)
				Return (One)
			}
			If ((Arg0 == 0x05))
			{
				OWGD (One)
				Return (One)
			}
			If ((Arg0 == 0x80))
			{
				Return (One)
			}
		}
		Method (_STA, 0, NotSerialized)  // _STA: Status
		{
			If ((MSOS () >= OSW8))
			{
				Return (0x0F)
			}
			Else
			{
				Return (Zero)
			}
		}
	}

On the Asus laptops that do not have an airplane mode LED, OWGD has an
empty implementation and OWGS simply returns 0. On the ones that have an
airplane mode LED these methods have the following implementation:

	Method (OWGD, 1, Serialized)
	{
		SGPL (0x0203000F, Arg0)
		SGPL (0x0203000F, Arg0)
	}

	Method (OWGS, 0, Serialized)
	{
		Store (RGPL (0x0203000F), Local0)
		Return (Local0)
	}

Where OWGD(1) sets the airplane mode LED ON, OWGD(0) set it off, and
OWGS() returns its state.

This commit exposes the airplane mode indicator LED to userspace under
the name asus-wireless::airplane, so it can be driven according to
userspace's policy.

Signed-off-by: João Paulo Rechi Vita <jprvita@endlessm.com>
Reviewed-by: Corentin Chary <corentin.chary@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

drivers/platform/x86/Kconfig

@@ -604,6 +604,8 @@ config ASUS_WIRELESS
 	tristate "Asus Wireless Radio Control Driver"
 	depends on ACPI
 	depends on INPUT
+	select NEW_LEDS
+	select LEDS_CLASS
 	---help---
 	  The Asus Wireless Radio Control handles the airplane mode hotkey
 	  present on some Asus laptops.

drivers/platform/x86/asus-wireless.c

@@ -15,11 +15,78 @@
 #include <linux/acpi.h>
 #include <linux/input.h>
 #include <linux/pci_ids.h>
+#include <linux/leds.h>
+
+#define ASUS_WIRELESS_LED_STATUS 0x2
+#define ASUS_WIRELESS_LED_OFF 0x4
+#define ASUS_WIRELESS_LED_ON 0x5
 
 struct asus_wireless_data {
 	struct input_dev *idev;
+	struct acpi_device *adev;
+	struct workqueue_struct *wq;
+	struct work_struct led_work;
+	struct led_classdev led;
+	int led_state;
 };
 
+static u64 asus_wireless_method(acpi_handle handle, const char *method,
+				int param)
+{
+	struct acpi_object_list p;
+	union acpi_object obj;
+	acpi_status s;
+	u64 ret;
+
+	acpi_handle_debug(handle, "Evaluating method %s, parameter %#x\n",
+			  method, param);
+	obj.type = ACPI_TYPE_INTEGER;
+	obj.integer.value = param;
+	p.count = 1;
+	p.pointer = &obj;
+
+	s = acpi_evaluate_integer(handle, (acpi_string) method, &p, &ret);
+	if (ACPI_FAILURE(s))
+		acpi_handle_err(handle,
+				"Failed to eval method %s, param %#x (%d)\n",
+				method, param, s);
+	acpi_handle_debug(handle, "%s returned %#x\n", method, (uint) ret);
+	return ret;
+}
+
+static enum led_brightness led_state_get(struct led_classdev *led)
+{
+	struct asus_wireless_data *data;
+	int s;
+
+	data = container_of(led, struct asus_wireless_data, led);
+	s = asus_wireless_method(acpi_device_handle(data->adev), "HSWC",
+				 ASUS_WIRELESS_LED_STATUS);
+	if (s == ASUS_WIRELESS_LED_ON)
+		return LED_FULL;
+	return LED_OFF;
+}
+
+static void led_state_update(struct work_struct *work)
+{
+	struct asus_wireless_data *data;
+
+	data = container_of(work, struct asus_wireless_data, led_work);
+	asus_wireless_method(acpi_device_handle(data->adev), "HSWC",
+			     data->led_state);
+}
+
+static void led_state_set(struct led_classdev *led,
+				  enum led_brightness value)
+{
+	struct asus_wireless_data *data;
+
+	data = container_of(led, struct asus_wireless_data, led);
+	data->led_state = value == LED_OFF ? ASUS_WIRELESS_LED_OFF :
+					     ASUS_WIRELESS_LED_ON;
+	queue_work(data->wq, &data->led_work);
+}
+
 static void asus_wireless_notify(struct acpi_device *adev, u32 event)
 {
 	struct asus_wireless_data *data = acpi_driver_data(adev);
@@ -37,6 +104,7 @@ static void asus_wireless_notify(struct acpi_device *adev, u32 event)
 static int asus_wireless_add(struct acpi_device *adev)
 {
 	struct asus_wireless_data *data;
+	int err;
 
 	data = devm_kzalloc(&adev->dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
@@ -52,11 +120,32 @@ static int asus_wireless_add(struct acpi_device *adev)
 	data->idev->id.vendor = PCI_VENDOR_ID_ASUSTEK;
 	set_bit(EV_KEY, data->idev->evbit);
 	set_bit(KEY_RFKILL, data->idev->keybit);
-	return input_register_device(data->idev);
+	err = input_register_device(data->idev);
+	if (err)
+		return err;
+
+	data->adev = adev;
+	data->wq = create_singlethread_workqueue("asus_wireless_workqueue");
+	if (!data->wq)
+		return -ENOMEM;
+	INIT_WORK(&data->led_work, led_state_update);
+	data->led.name = "asus-wireless::airplane";
+	data->led.brightness_set = led_state_set;
+	data->led.brightness_get = led_state_get;
+	data->led.flags = LED_CORE_SUSPENDRESUME;
+	data->led.max_brightness = 1;
+	err = devm_led_classdev_register(&adev->dev, &data->led);
+	if (err)
+		destroy_workqueue(data->wq);
+	return err;
 }
 
 static int asus_wireless_remove(struct acpi_device *adev)
 {
+	struct asus_wireless_data *data = acpi_driver_data(adev);
+
+	if (data->wq)
+		destroy_workqueue(data->wq);
 	return 0;
 }