[RFC PATCH 2/3] platform: lenovo: add WMI hotkeys driver

[David Cemin <dcemin@nvidia.com>]

Lenovo consumer laptops deliver their vendor specific Fn keys (microphone
mute, airplane mode, performance mode, the Smart Key and Smart Connect
keys) as WMI events on GUID 8FC0DE0C-B4E4-43FD-B0F3-8871711C1294 instead
of keyboard usages. On x86, ideapad-laptop consumes these events, but it
depends on i8042 and on the IdeaPad VPC ACPI device, neither of which
exist on the ACPI based arm64 models. Add a small WMI driver that reports
the same key codes through a sparse keymap, so desktops see the generic
input events.

The key map follows ideapad-laptop. One code seen on the Yoga 9 2-in-1
16 (arm64) is new: 0x48 for the Smart Connect key.

Both drivers match the same GUID. The probe declines when the IdeaPad
VPC device (VPC2004) is present, so machines handled by ideapad-laptop,
including its Fn lock LED and DYTC performance mode handling, keep that
driver.

Signed-off-by: David Cemin <dcemin@nvidia.com>
---
 MAINTAINERS                           |   6 +
 drivers/platform/lenovo/Kconfig       |  14 +++
 drivers/platform/lenovo/Makefile      |   1 +
 drivers/platform/lenovo/wmi-hotkeys.c | 151 ++++++++++++++++++++++++++
 4 files changed, 172 insertions(+)
 create mode 100644 drivers/platform/lenovo/wmi-hotkeys.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 3b0ad5a3debe..207684aeaf69 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15173,6 +15173,12 @@ F:	Documentation/wmi/devices/lenovo-wmi-other.rst
 F:	drivers/platform/lenovo/
 F:	drivers/platform/x86/lenovo/*
 
+LENOVO WMI HOTKEYS DRIVER
+M:	David Cemin <dcemin@nvidia.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	drivers/platform/lenovo/wmi-hotkeys.c
+
 LENOVO WMI HOTKEY UTILITIES DRIVER
 M:	Jackie Dong <xy-jackie@139.com>
 L:	platform-driver-x86@vger.kernel.org
diff --git a/drivers/platform/lenovo/Kconfig b/drivers/platform/lenovo/Kconfig
index 8222322ca671..ba4248d56e5f 100644
--- a/drivers/platform/lenovo/Kconfig
+++ b/drivers/platform/lenovo/Kconfig
@@ -41,6 +41,20 @@ config LENOVO_WMI_HOTKEY_UTILITIES
 	  such as LED control for audio/mic mute event for Ideapad, YOGA, XiaoXin,
 	  Gaming, ThinkBook and so on.
 
+config LENOVO_WMI_HOTKEYS
+	tristate "Lenovo WMI hotkeys driver"
+	depends on ACPI_WMI
+	depends on INPUT
+	select INPUT_SPARSEKMAP
+	help
+	  Say Y or M here to enable the vendor specific Fn keys (microphone
+	  mute, airplane mode, performance mode, star key) on Lenovo laptops
+	  that deliver them as WMI events and are not handled by the
+	  ideapad-laptop driver, such as the ACPI based arm64 models.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called lenovo-wmi-hotkeys.
+
 config LENOVO_WMI_CAMERA
 	tristate "Lenovo WMI Camera Button driver"
 	depends on ACPI_WMI
diff --git a/drivers/platform/lenovo/Makefile b/drivers/platform/lenovo/Makefile
index 1cac115dd735..d3f5e3ac14c2 100644
--- a/drivers/platform/lenovo/Makefile
+++ b/drivers/platform/lenovo/Makefile
@@ -8,6 +8,7 @@ lenovo-target-$(CONFIG_LENOVO_WMI_HELPERS)	+= wmi-helpers.o
 lenovo-target-$(CONFIG_LENOVO_WMI_EVENTS)	+= wmi-events.o
 lenovo-target-$(CONFIG_LENOVO_WMI_CAPDATA)	+= wmi-capdata.o
 lenovo-target-$(CONFIG_LENOVO_WMI_HOTKEY_UTILITIES)	+= wmi-hotkey-utilities.o
+lenovo-target-$(CONFIG_LENOVO_WMI_HOTKEYS)	+= wmi-hotkeys.o
 lenovo-target-$(CONFIG_LENOVO_WMI_CAMERA)	+= wmi-camera.o
 lenovo-target-$(CONFIG_LENOVO_WMI_GAMEZONE)	+= wmi-gamezone.o
 lenovo-target-$(CONFIG_LENOVO_WMI_TUNING)	+= wmi-other.o
diff --git a/drivers/platform/lenovo/wmi-hotkeys.c b/drivers/platform/lenovo/wmi-hotkeys.c
new file mode 100644
index 000000000000..fc18867d8144
--- /dev/null
+++ b/drivers/platform/lenovo/wmi-hotkeys.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Lenovo WMI hotkey driver
+ *
+ * Lenovo consumer laptops deliver their vendor specific Fn keys (microphone
+ * mute, airplane mode, performance mode, the star key and others) as WMI
+ * events on GUID 8FC0DE0C-B4E4-43FD-B0F3-8871711C1294 instead of keyboard
+ * usages.  On x86 ideapad-laptop consumes these events; that driver depends
+ * on i8042 and the IdeaPad VPC device, neither of which exist on the arm64
+ * platforms.  This driver consumes the same event and reports the keys the
+ * same way, so desktops see the usual generic key codes.
+ *
+ * The key codes follow the mapping used by ideapad-laptop.
+ */
+
+#include <linux/acpi.h>
+#include <linux/input.h>
+#include <linux/input/sparse-keymap.h>
+#include <linux/module.h>
+#include <linux/wmi.h>
+
+#define LENOVO_FN_KEYS_WMI_GUID	"8FC0DE0C-B4E4-43FD-B0F3-8871711C1294"
+
+static const struct key_entry lenovo_wmi_hotkeys_keymap[] = {
+	/* Customizable Lenovo Hotkey ("star" with 'S' inside) */
+	{ KE_KEY, 0x01, { KEY_FAVORITES } },
+	/* Fn lock toggled on / off, firmware handles the LED */
+	{ KE_IGNORE, 0x02 },
+	{ KE_IGNORE, 0x03 },
+	{ KE_KEY, 0x04, { KEY_SELECTIVE_SCREENSHOT } },
+	/* Lenovo Support */
+	{ KE_KEY, 0x07, { KEY_HELP } },
+	{ KE_KEY, 0x0a, { KEY_REFRESH_RATE_TOGGLE } },
+	{ KE_KEY, 0x0e, { KEY_PICKUP_PHONE } },
+	{ KE_KEY, 0x0f, { KEY_HANGUP_PHONE } },
+	{ KE_KEY, 0x10, { KEY_REFRESH_RATE_TOGGLE } },
+	/* Sound profile switch */
+	{ KE_KEY, 0x12, { KEY_PROG2 } },
+	/* Dark mode toggle */
+	{ KE_KEY, 0x13, { KEY_PROG1 } },
+	/* Lenovo Support */
+	{ KE_KEY, 0x27, { KEY_HELP } },
+	/* Lenovo Virtual Background application */
+	{ KE_KEY, 0x28, { KEY_PROG3 } },
+	{ KE_KEY, 0x29, { KEY_TOUCHPAD_TOGGLE } },
+	{ KE_KEY, 0x2a, { KEY_ROOT_MENU } },
+	/* Shift + PrtSc */
+	{ KE_KEY, 0x2d, { KEY_SELECTIVE_SCREENSHOT } },
+	/* Performance mode, Fn+Q */
+	{ KE_KEY, 0x3d, { KEY_PROG4 } },
+	{ KE_KEY, 0x3e, { KEY_MICMUTE } },
+	{ KE_KEY, 0x3f, { KEY_RFKILL } },
+	/*
+	 * Keyboard backlight level after Fn+Space, handled by the firmware:
+	 * 0x40 off, 0x41 low, 0x42 high, 0x43 also seen
+	 */
+	{ KE_IGNORE, 0x40 },
+	{ KE_IGNORE, 0x41 },
+	{ KE_IGNORE, 0x42 },
+	{ KE_IGNORE, 0x43 },
+	/* Star, user assignable key */
+	{ KE_KEY, 0x44, { KEY_PROG1 } },
+	/* Eye care */
+	{ KE_KEY, 0x45, { KEY_PROG3 } },
+	/* Smart Connect, phone to PC link */
+	{ KE_KEY, 0x48, { KEY_PROG2 } },
+	{ KE_END },
+};
+
+struct lenovo_wmi_hotkeys {
+	struct input_dev *input;
+};
+
+static int lenovo_wmi_hotkeys_probe(struct wmi_device *wdev, const void *context)
+{
+	struct lenovo_wmi_hotkeys *priv;
+	int ret;
+
+	/*
+	 * ideapad-laptop binds the same GUID and handles these events together
+	 * with the IdeaPad VPC device (Fn lock LED, DYTC performance mode
+	 * cycling).  Leave those machines to it.
+	 */
+	if (acpi_dev_found("VPC2004")) {
+		dev_dbg(&wdev->dev, "IdeaPad VPC present, deferring to ideapad-laptop\n");
+		return -ENODEV;
+	}
+
+	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->input = devm_input_allocate_device(&wdev->dev);
+	if (!priv->input)
+		return -ENOMEM;
+
+	priv->input->name = "Lenovo WMI hotkeys";
+	priv->input->phys = "wmi/input0";
+	priv->input->id.bustype = BUS_HOST;
+	priv->input->dev.parent = &wdev->dev;
+
+	ret = sparse_keymap_setup(priv->input, lenovo_wmi_hotkeys_keymap, NULL);
+	if (ret)
+		return ret;
+
+	ret = input_register_device(priv->input);
+	if (ret)
+		return ret;
+
+	dev_set_drvdata(&wdev->dev, priv);
+
+	return 0;
+}
+
+static void lenovo_wmi_hotkeys_notify(struct wmi_device *wdev, union acpi_object *data)
+{
+	struct lenovo_wmi_hotkeys *priv = dev_get_drvdata(&wdev->dev);
+	u32 code;
+
+	if (!data || data->type != ACPI_TYPE_INTEGER) {
+		dev_dbg(&wdev->dev, "event data is not an integer\n");
+		return;
+	}
+
+	code = data->integer.value;
+	dev_dbg(&wdev->dev, "hotkey event 0x%x\n", code);
+
+	if (!sparse_keymap_report_event(priv->input, code, 1, true))
+		dev_info_ratelimited(&wdev->dev, "unknown hotkey event 0x%x\n", code);
+}
+
+static const struct wmi_device_id lenovo_wmi_hotkeys_id_table[] = {
+	{ LENOVO_FN_KEYS_WMI_GUID, NULL },
+	{ }
+};
+MODULE_DEVICE_TABLE(wmi, lenovo_wmi_hotkeys_id_table);
+
+static struct wmi_driver lenovo_wmi_hotkeys_driver = {
+	.driver = {
+		.name = "lenovo-wmi-hotkeys",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = lenovo_wmi_hotkeys_id_table,
+	.probe = lenovo_wmi_hotkeys_probe,
+	.notify = lenovo_wmi_hotkeys_notify,
+	.no_singleton = true,
+};
+module_wmi_driver(lenovo_wmi_hotkeys_driver);
+
+MODULE_DESCRIPTION("Lenovo WMI hotkey driver");
+MODULE_LICENSE("GPL");
-- 
2.56.1