[PATCH 1/2] Input: soc_button_array - add support for Microsoft Surface 3 (MSHW0028) buttons

[Hans de Goede <hdegoede@redhat.com>]

The drivers/platform/surface/surface3_button.c code is alsmost a 1:1 copy
of the soc_button_array code.

The only big difference is that it binds to an i2c_client rather then to
a platform_device. The cause of this is the ACPI resources for the MSHW0028
device containing a bogus I2cSerialBusV2 resource which causes the kernel
to instantiate an i2c_client for it instead of a platform_device.

Add "MSHW0028" to the ignore_serial_bus_ids[] list in drivers/apci/scan.c,
so that a platform_device will be instantiated and add support for
the MSHW0028 HID to soc_button_array.

This fully replaces surface3_button, which will be removed in a separate
commit (since it binds to the now no longer created i2c_client it no
longer does anyyhing after this commit).

Note the MSHW0028 id is used by Microsoft to describe the tablet buttons on
both the Surface 3 and the Surface 3 Pro and the actual API/implementation
for the Surface 3 Pro is quite different. The changes in this commit should
not impact the separate surfacepro3_button driver:

1. Because of the bogus I2cSerialBusV2 resource problem that driver binds
   to the acpi_device itself, so instantiating a platform_device instead of
   an i2c_client does not matter.

2. The soc_button_array driver will not bind to the MSHW0028 device on
   the Surface 3 Pro, because it has no GPIO resources.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/acpi/scan.c                   |  5 +++++
 drivers/input/misc/soc_button_array.c | 24 +++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 4463c2eda61e..e993c8b253f5 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1749,6 +1749,11 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
 		{"INT3515", },
 		/* Non-conforming _HID for Cirrus Logic already released */
 		{"CLSA0100", },
+	/*
+	 * Some ACPI devs contain SerialBus resources even though they are not
+	 * attached to a serial bus at all.
+	 */
+		{"MSHW0028", },
 	/*
 	 * HIDs of device with an UartSerialBusV2 resource for which userspace
 	 * expects a regular tty cdev to be created (instead of the in kernel
diff --git a/drivers/input/misc/soc_button_array.c b/drivers/input/misc/soc_button_array.c
index cb6ec59a045d..cbb1599a520e 100644
--- a/drivers/input/misc/soc_button_array.c
+++ b/drivers/input/misc/soc_button_array.c
@@ -469,6 +469,27 @@ static const struct soc_device_data soc_device_INT33D3 = {
 	.button_info = soc_button_INT33D3,
 };
 
+/*
+ * Button info for Microsoft Surface 3 (non pro), this is indentical to
+ * the PNP0C40 info except that the home button is active-high.
+ *
+ * The Surface 3 Pro also has a MSHW0028 ACPI device, but that uses a custom
+ * version of the drivers/platform/x86/intel/hid.c 5 button array ACPI API
+ * instead. A check() callback is not necessary though as the Surface 3 Pro
+ * MSHW0028 ACPI device's resource table does not contain any GPIOs.
+ */
+static const struct soc_button_info soc_button_MSHW0028[] = {
+	{ "power", 0, EV_KEY, KEY_POWER, false, true, true },
+	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
+	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
+	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
+	{ }
+};
+
+static const struct soc_device_data soc_device_MSHW0028 = {
+	.button_info = soc_button_MSHW0028,
+};
+
 /*
  * Special device check for Surface Book 2 and Surface Pro (2017).
  * Both, the Surface Pro 4 (surfacepro3_button.c) and the above mentioned
@@ -535,7 +556,8 @@ static const struct acpi_device_id soc_button_acpi_match[] = {
 	{ "ID9001", (unsigned long)&soc_device_INT33D3 },
 	{ "ACPI0011", 0 },
 
-	/* Microsoft Surface Devices (5th and 6th generation) */
+	/* Microsoft Surface Devices (3th, 5th and 6th generation) */
+	{ "MSHW0028", (unsigned long)&soc_device_MSHW0028 },
 	{ "MSHW0040", (unsigned long)&soc_device_MSHW0040 },
 
 	{ }
-- 
2.35.1