platform/x86: Add and use a dual_accel_detect() helper

Various 360 degree hinges (yoga) style 2-in-1 devices use 2 accelerometers
to allow the OS to determine the angle between the display and the base of
the device.

On Windows these are read by a special HingeAngleService process which
calls undocumented ACPI methods, to let the firmware know if the 2-in-1 is
in tablet- or laptop-mode. The firmware may use this to disable the kbd and
touchpad to avoid spurious input in tablet-mode as well as to report
SW_TABLET_MODE info to the OS.

Since Linux does not call these undocumented methods, the SW_TABLET_MODE
info reported by various pdx86 drivers is incorrect on these devices.

Before this commit the intel-hid and thinkpad_acpi code already had 2
hardcoded checks for ACPI hardware-ids of dual-accel sensors to avoid
reporting broken info.

And now we also have a bug-report about the same problem in the intel-vbtn
code. Since there are at least 3 different ACPI hardware-ids in play, add
a new dual_accel_detect() helper which checks for all 3, rather then
adding different hardware-ids to the drivers as bug-reports trickle in.
Having shared code which checks all known hardware-ids is esp. important
for the intel-hid and intel-vbtn drivers as these are generic drivers
which are used on a lot of devices.

The BOSC0200 hardware-id requires special handling, because often it is
used for a single-accelerometer setup. Only in a few cases it refers to
a dual-accel setup, in which case there will be 2 I2cSerialBus resources
in the device's resource-list, so the helper checks for this.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=209011
Reported-and-tested-by: Julius Lehmann <julius@devpi.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210729082134.6683-1-hdegoede@redhat.com

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/platform/x86/intel-vbtn.c b/drivers/platform/x86/intel-vbtn.c
index 888a764efad1..309166431063 100644
--- a/drivers/platform/x86/intel-vbtn.c
+++ b/drivers/platform/x86/intel-vbtn.c
@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/suspend.h>
+#include "dual_accel_detect.h"
 
 /* Returned when NOT in tablet mode on some HP Stream x360 11 models */
 #define VGBS_TABLET_MODE_FLAG_ALT	0x10
@@ -66,6 +67,7 @@ static const struct key_entry intel_vbtn_switchmap[] = {
 struct intel_vbtn_priv {
 	struct input_dev *buttons_dev;
 	struct input_dev *switches_dev;
+	bool dual_accel;
 	bool has_buttons;
 	bool has_switches;
 	bool wakeup_mode;
@@ -160,6 +162,10 @@ static void notify_handler(acpi_handle handle, u32 event, void *context)
 		input_dev = priv->buttons_dev;
 	} else if ((ke = sparse_keymap_entry_from_scancode(priv->switches_dev, event))) {
 		if (!priv->has_switches) {
+			/* See dual_accel_detect.h for more info */
+			if (priv->dual_accel)
+				return;
+
 			dev_info(&device->dev, "Registering Intel Virtual Switches input-dev after receiving a switch event\n");
 			ret = input_register_device(priv->switches_dev);
 			if (ret)
@@ -248,11 +254,15 @@ static const struct dmi_system_id dmi_switches_allow_list[] = {
 	{} /* Array terminator */
 };
 
-static bool intel_vbtn_has_switches(acpi_handle handle)
+static bool intel_vbtn_has_switches(acpi_handle handle, bool dual_accel)
 {
 	unsigned long long vgbs;
 	acpi_status status;
 
+	/* See dual_accel_detect.h for more info */
+	if (dual_accel)
+		return false;
+
 	if (!dmi_check_system(dmi_switches_allow_list))
 		return false;
 
@@ -263,13 +273,14 @@ static bool intel_vbtn_has_switches(acpi_handle handle)
 static int intel_vbtn_probe(struct platform_device *device)
 {
 	acpi_handle handle = ACPI_HANDLE(&device->dev);
-	bool has_buttons, has_switches;
+	bool dual_accel, has_buttons, has_switches;
 	struct intel_vbtn_priv *priv;
 	acpi_status status;
 	int err;
 
+	dual_accel = dual_accel_detect();
 	has_buttons = acpi_has_method(handle, "VBDL");
-	has_switches = intel_vbtn_has_switches(handle);
+	has_switches = intel_vbtn_has_switches(handle, dual_accel);
 
 	if (!has_buttons && !has_switches) {
 		dev_warn(&device->dev, "failed to read Intel Virtual Button driver\n");
@@ -281,6 +292,7 @@ static int intel_vbtn_probe(struct platform_device *device)
 		return -ENOMEM;
 	dev_set_drvdata(&device->dev, priv);
 
+	priv->dual_accel = dual_accel;
 	priv->has_buttons = has_buttons;
 	priv->has_switches = has_switches;