platform/x86: acer-wmi: Add support for SW_TABLET_MODE on Switch devices

Add support for SW_TABLET_MODE on the Acer Switch 10 (SW5-012) and the
acer Switch 10 (S1003) models.

There is no way to detect if this is supported, so this uses DMI based
quirks setting force_caps to ACER_CAP_KBD_DOCK (these devices have no
other acer-wmi based functionality).

The new SW_TABLET_MODE functionality can be tested on devices which
are not in the DMI table by passing acer_wmi.force_caps=0x40 on the
kernel commandline.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20201019185628.264473-6-hdegoede@redhat.com

drivers/platform/x86/acer-wmi.c

@@ -30,6 +30,7 @@
 #include <linux/input/sparse-keymap.h>
 #include <acpi/video.h>
 
+ACPI_MODULE_NAME(KBUILD_MODNAME);
 MODULE_AUTHOR("Carlos Corbacho");
 MODULE_DESCRIPTION("Acer Laptop WMI Extras Driver");
 MODULE_LICENSE("GPL");
@@ -80,7 +81,7 @@ MODULE_ALIAS("wmi:676AA15E-6A47-4D9F-A2CC-1E6D18D14026");
 
 enum acer_wmi_event_ids {
 	WMID_HOTKEY_EVENT = 0x1,
-	WMID_ACCEL_EVENT = 0x5,
+	WMID_ACCEL_OR_KBD_DOCK_EVENT = 0x5,
 };
 
 static const struct key_entry acer_wmi_keymap[] __initconst = {
@@ -127,7 +128,9 @@ struct event_return_value {
 	u8 function;
 	u8 key_num;
 	u16 device_state;
-	u32 reserved;
+	u16 reserved1;
+	u8 kbd_dock_state;
+	u8 reserved2;
 } __attribute__((packed));
 
 /*
@@ -211,6 +214,7 @@ struct hotkey_function_type_aa {
 #define ACER_CAP_BRIGHTNESS		BIT(3)
 #define ACER_CAP_THREEG			BIT(4)
 #define ACER_CAP_SET_FUNCTION_MODE	BIT(5)
+#define ACER_CAP_KBD_DOCK		BIT(6)
 
 /*
  * Interface type flags
@@ -316,6 +320,15 @@ static int __init dmi_matched(const struct dmi_system_id *dmi)
 	return 1;
 }
 
+static int __init set_force_caps(const struct dmi_system_id *dmi)
+{
+	if (force_caps == -1) {
+		force_caps = (uintptr_t)dmi->driver_data;
+		pr_info("Found %s, set force_caps to 0x%x\n", dmi->ident, force_caps);
+	}
+	return 1;
+}
+
 static struct quirk_entry quirk_unknown = {
 };
 
@@ -494,6 +507,24 @@ static const struct dmi_system_id acer_quirks[] __initconst = {
 		},
 		.driver_data = &quirk_acer_travelmate_2490,
 	},
+	{
+		.callback = set_force_caps,
+		.ident = "Acer Aspire Switch 10 SW5-012",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire SW5-012"),
+		},
+		.driver_data = (void *)ACER_CAP_KBD_DOCK,
+	},
+	{
+		.callback = set_force_caps,
+		.ident = "Acer One 10 (S1003)",
+		.matches = {
+			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Acer"),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "One S1003"),
+		},
+		.driver_data = (void *)ACER_CAP_KBD_DOCK,
+	},
 	{}
 };
 
@@ -1535,6 +1566,71 @@ static int acer_gsensor_event(void)
 	return 0;
 }
 
+/*
+ * Switch series keyboard dock status
+ */
+static int acer_kbd_dock_state_to_sw_tablet_mode(u8 kbd_dock_state)
+{
+	switch (kbd_dock_state) {
+	case 0x01: /* Docked, traditional clamshell laptop mode */
+		return 0;
+	case 0x04: /* Stand-alone tablet */
+	case 0x40: /* Docked, tent mode, keyboard not usable */
+		return 1;
+	default:
+		pr_warn("Unknown kbd_dock_state 0x%02x\n", kbd_dock_state);
+	}
+
+	return 0;
+}
+
+static void acer_kbd_dock_get_initial_state(void)
+{
+	u8 *output, input[8] = { 0x05, 0x00, };
+	struct acpi_buffer input_buf = { sizeof(input), input };
+	struct acpi_buffer output_buf = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+	int sw_tablet_mode;
+
+	status = wmi_evaluate_method(WMID_GUID3, 0, 0x2, &input_buf, &output_buf);
+	if (ACPI_FAILURE(status)) {
+		ACPI_EXCEPTION((AE_INFO, status, "Error getting keyboard-dock initial status"));
+		return;
+	}
+
+	obj = output_buf.pointer;
+	if (!obj || obj->type != ACPI_TYPE_BUFFER || obj->buffer.length != 8) {
+		pr_err("Unexpected output format getting keyboard-dock initial status\n");
+		goto out_free_obj;
+	}
+
+	output = obj->buffer.pointer;
+	if (output[0] != 0x00 || (output[3] != 0x05 && output[3] != 0x45)) {
+		pr_err("Unexpected output [0]=0x%02x [3]=0x%02x getting keyboard-dock initial status\n",
+		       output[0], output[3]);
+		goto out_free_obj;
+	}
+
+	sw_tablet_mode = acer_kbd_dock_state_to_sw_tablet_mode(output[4]);
+	input_report_switch(acer_wmi_input_dev, SW_TABLET_MODE, sw_tablet_mode);
+
+out_free_obj:
+	kfree(obj);
+}
+
+static void acer_kbd_dock_event(const struct event_return_value *event)
+{
+	int sw_tablet_mode;
+
+	if (!has_cap(ACER_CAP_KBD_DOCK))
+		return;
+
+	sw_tablet_mode = acer_kbd_dock_state_to_sw_tablet_mode(event->kbd_dock_state);
+	input_report_switch(acer_wmi_input_dev, SW_TABLET_MODE, sw_tablet_mode);
+	input_sync(acer_wmi_input_dev);
+}
+
 /*
  * Rfkill devices
  */
@@ -1762,8 +1858,9 @@ static void acer_wmi_notify(u32 value, void *context)
 			sparse_keymap_report_event(acer_wmi_input_dev, scancode, 1, true);
 		}
 		break;
-	case WMID_ACCEL_EVENT:
+	case WMID_ACCEL_OR_KBD_DOCK_EVENT:
 		acer_gsensor_event();
+		acer_kbd_dock_event(&return_value);
 		break;
 	default:
 		pr_warn("Unknown function number - %d - %d\n",
@@ -1928,6 +2025,9 @@ static int __init acer_wmi_input_setup(void)
 	if (err)
 		goto err_free_dev;
 
+	if (has_cap(ACER_CAP_KBD_DOCK))
+		input_set_capability(acer_wmi_input_dev, EV_SW, SW_TABLET_MODE);
+
 	status = wmi_install_notify_handler(ACERWMID_EVENT_GUID,
 						acer_wmi_notify, NULL);
 	if (ACPI_FAILURE(status)) {
@@ -1935,6 +2035,9 @@ static int __init acer_wmi_input_setup(void)
 		goto err_free_dev;
 	}
 
+	if (has_cap(ACER_CAP_KBD_DOCK))
+		acer_kbd_dock_get_initial_state();
+
 	err = input_register_device(acer_wmi_input_dev);
 	if (err)
 		goto err_uninstall_notifier;