platform/x86: add support for Huawei WMI hotkeys

This driver adds support for missing hotkeys on some Huawei laptops.
Laptops such as the Matebook X have non functioning hotkeys. Whereas
newer laptops such as the Matebook X Pro come with working hotkeys out
of the box.

Old laptops, such as the Matebook X, report hotkey events through ACPI
device "\WMI0". However, new laptops, such as the Matebook X Pro, does
not have this WMI device.

All the hotkeys on the Matebook X Pro work fine without this patch
except (micmute, wlan, and huawei key). These keys and the brightness
keys report events to "\AMW0" ACPI device. One problem is that
brightness keys on the Matebook X Pro work without this patch. This
results in reporting two brightness key press events one is captured
by ACPI and another by this driver.

A solution would be to check if such event came from the "\AMW0" WMI
driver then skip reporting event. Another solution would be to leave
this to user-space to handle. Which can be achieved by using "hwdb"
tables and remap those keys to "unknown". This solution seems more
natural to me because it leaves the decision to user-space.
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ayman Bagabas <ayman.bagabas@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

drivers/platform/x86/Kconfig

@@ -1292,6 +1292,23 @@ config INTEL_ATOMISP2_PM
 	  To compile this driver as a module, choose M here: the module
 	  will be called intel_atomisp2_pm.
 
+config HUAWEI_WMI
+	tristate "Huawei WMI hotkeys driver"
+	depends on ACPI_WMI
+	depends on INPUT
+	select INPUT_SPARSEKMAP
+	select LEDS_CLASS
+	select LEDS_TRIGGERS
+	select LEDS_TRIGGER_AUDIO
+	select NEW_LEDS
+	help
+	  This driver provides support for Huawei WMI hotkeys.
+	  It enables the missing keys and adds support to the micmute
+	  LED found on some of these laptops.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called huawei-wmi.
+
 endif # X86_PLATFORM_DEVICES
 
 config PMC_ATOM

drivers/platform/x86/Makefile

@@ -32,6 +32,7 @@ obj-$(CONFIG_ACERHDF)		+= acerhdf.o
 obj-$(CONFIG_HP_ACCEL)		+= hp_accel.o
 obj-$(CONFIG_HP_WIRELESS)	+= hp-wireless.o
 obj-$(CONFIG_HP_WMI)		+= hp-wmi.o
+obj-$(CONFIG_HUAWEI_WMI)		+= huawei-wmi.o
 obj-$(CONFIG_AMILO_RFKILL)	+= amilo-rfkill.o
 obj-$(CONFIG_GPD_POCKET_FAN)	+= gpd-pocket-fan.o
 obj-$(CONFIG_TC1100_WMI)	+= tc1100-wmi.o

drivers/platform/x86/huawei-wmi.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Huawei WMI hotkeys
+ *
+ *  Copyright (C) 2018	      Ayman Bagabas <ayman.bagabas@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/input.h>
+#include <linux/input/sparse-keymap.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/wmi.h>
+
+/*
+ * Huawei WMI GUIDs
+ */
+#define WMI0_EVENT_GUID "59142400-C6A3-40fa-BADB-8A2652834100"
+#define AMW0_EVENT_GUID "ABBC0F5C-8EA1-11D1-A000-C90629100000"
+
+#define WMI0_EXPENSIVE_GUID "39142400-C6A3-40fa-BADB-8A2652834100"
+
+struct huawei_wmi_priv {
+	struct input_dev *idev;
+	struct led_classdev cdev;
+	acpi_handle handle;
+	char *acpi_method;
+};
+
+static const struct key_entry huawei_wmi_keymap[] = {
+	{ KE_KEY,    0x281, { KEY_BRIGHTNESSDOWN } },
+	{ KE_KEY,    0x282, { KEY_BRIGHTNESSUP } },
+	{ KE_KEY,    0x284, { KEY_MUTE } },
+	{ KE_KEY,    0x285, { KEY_VOLUMEDOWN } },
+	{ KE_KEY,    0x286, { KEY_VOLUMEUP } },
+	{ KE_KEY,    0x287, { KEY_MICMUTE } },
+	{ KE_KEY,    0x289, { KEY_WLAN } },
+	// Huawei |M| key
+	{ KE_KEY,    0x28a, { KEY_CONFIG } },
+	// Keyboard backlight
+	{ KE_IGNORE, 0x293, { KEY_KBDILLUMTOGGLE } },
+	{ KE_IGNORE, 0x294, { KEY_KBDILLUMUP } },
+	{ KE_IGNORE, 0x295, { KEY_KBDILLUMUP } },
+	{ KE_END,	 0 }
+};
+
+static int huawei_wmi_micmute_led_set(struct led_classdev *led_cdev,
+		enum led_brightness brightness)
+{
+	struct huawei_wmi_priv *priv = dev_get_drvdata(led_cdev->dev->parent);
+	acpi_status status;
+	union acpi_object args[3];
+	struct acpi_object_list arg_list = {
+		.pointer = args,
+		.count = ARRAY_SIZE(args),
+	};
+
+	args[0].type = args[1].type = args[2].type = ACPI_TYPE_INTEGER;
+	args[1].integer.value = 0x04;
+
+	if (strcmp(priv->acpi_method, "SPIN") == 0) {
+		args[0].integer.value = 0;
+		args[2].integer.value = brightness ? 1 : 0;
+	} else if (strcmp(priv->acpi_method, "WPIN") == 0) {
+		args[0].integer.value = 1;
+		args[2].integer.value = brightness ? 0 : 1;
+	} else {
+		return -EINVAL;
+	}
+
+	status = acpi_evaluate_object(priv->handle, priv->acpi_method, &arg_list, NULL);
+	if (ACPI_FAILURE(status))
+		return -ENXIO;
+
+	return 0;
+}
+
+static int huawei_wmi_leds_setup(struct wmi_device *wdev)
+{
+	struct huawei_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
+
+	priv->handle = ec_get_handle();
+	if (!priv->handle)
+		return 0;
+
+	if (acpi_has_method(priv->handle, "SPIN"))
+		priv->acpi_method = "SPIN";
+	else if (acpi_has_method(priv->handle, "WPIN"))
+		priv->acpi_method = "WPIN";
+	else
+		return 0;
+
+	priv->cdev.name = "platform::micmute";
+	priv->cdev.max_brightness = 1;
+	priv->cdev.brightness_set_blocking = huawei_wmi_micmute_led_set;
+	priv->cdev.default_trigger = "audio-micmute";
+	priv->cdev.brightness = ledtrig_audio_get(LED_AUDIO_MICMUTE);
+	priv->cdev.dev = &wdev->dev;
+	priv->cdev.flags = LED_CORE_SUSPENDRESUME;
+
+	return devm_led_classdev_register(&wdev->dev, &priv->cdev);
+}
+
+static void huawei_wmi_process_key(struct wmi_device *wdev, int code)
+{
+	struct huawei_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
+	const struct key_entry *key;
+
+	/*
+	 * WMI0 uses code 0x80 to indicate a hotkey event.
+	 * The actual key is fetched from the method WQ00
+	 * using WMI0_EXPENSIVE_GUID.
+	 */
+	if (code == 0x80) {
+		struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
+		union acpi_object *obj;
+		acpi_status status;
+
+		status = wmi_query_block(WMI0_EXPENSIVE_GUID, 0, &response);
+		if (ACPI_FAILURE(status))
+			return;
+
+		obj = (union acpi_object *)response.pointer;
+		if (obj && obj->type == ACPI_TYPE_INTEGER)
+			code = obj->integer.value;
+
+		kfree(response.pointer);
+	}
+
+	key = sparse_keymap_entry_from_scancode(priv->idev, code);
+	if (!key) {
+		dev_info(&wdev->dev, "Unknown key pressed, code: 0x%04x\n", code);
+		return;
+	}
+
+	sparse_keymap_report_entry(priv->idev, key, 1, true);
+}
+
+static void huawei_wmi_notify(struct wmi_device *wdev,
+		union acpi_object *obj)
+{
+	if (obj->type == ACPI_TYPE_INTEGER)
+		huawei_wmi_process_key(wdev, obj->integer.value);
+	else
+		dev_info(&wdev->dev, "Bad response type %d\n", obj->type);
+}
+
+static int huawei_wmi_input_setup(struct wmi_device *wdev)
+{
+	struct huawei_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
+	int err;
+
+	priv->idev = devm_input_allocate_device(&wdev->dev);
+	if (!priv->idev)
+		return -ENOMEM;
+
+	priv->idev->name = "Huawei WMI hotkeys";
+	priv->idev->phys = "wmi/input0";
+	priv->idev->id.bustype = BUS_HOST;
+	priv->idev->dev.parent = &wdev->dev;
+
+	err = sparse_keymap_setup(priv->idev, huawei_wmi_keymap, NULL);
+	if (err)
+		return err;
+
+	return input_register_device(priv->idev);
+}
+
+static int huawei_wmi_probe(struct wmi_device *wdev)
+{
+	struct huawei_wmi_priv *priv;
+	int err;
+
+	priv = devm_kzalloc(&wdev->dev, sizeof(struct huawei_wmi_priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	dev_set_drvdata(&wdev->dev, priv);
+
+	err = huawei_wmi_input_setup(wdev);
+	if (err)
+		return err;
+
+	return huawei_wmi_leds_setup(wdev);
+}
+
+static const struct wmi_device_id huawei_wmi_id_table[] = {
+	{ .guid_string = WMI0_EVENT_GUID },
+	{ .guid_string = AMW0_EVENT_GUID },
+	{  }
+};
+
+static struct wmi_driver huawei_wmi_driver = {
+	.driver = {
+		.name = "huawei-wmi",
+	},
+	.id_table = huawei_wmi_id_table,
+	.probe = huawei_wmi_probe,
+	.notify = huawei_wmi_notify,
+};
+
+module_wmi_driver(huawei_wmi_driver);
+
+MODULE_ALIAS("wmi:"WMI0_EVENT_GUID);
+MODULE_ALIAS("wmi:"AMW0_EVENT_GUID);
+MODULE_AUTHOR("Ayman Bagabas <ayman.bagabas@gmail.com>");
+MODULE_DESCRIPTION("Huawei WMI hotkeys");
+MODULE_LICENSE("GPL v2");