[PATCH 1/2] platform: Fix device check for surfacepro3_button

Maximilian Luz
2019-06-20T11:51:49Z

Do not use the surfacepro3_button driver on newer Microsoft Surface
models, only use it on the Surface Pro 3 and 4. Newer models (5th, 6th
and possibly future generations) use the same device as the Surface Pro
4 to represent their volume and power buttons (MSHW0040), but their
acutal implementation is significantly different. This patch ensures
that the surfacepro3_button driver is only used on the Pro 3 and 4
models, allowing a different driver to bind on other models.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
---
drivers/platform/x86/surfacepro3_button.c | 38 +++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/drivers/platform/x86/surfacepro3_button.c b/drivers/platform/x86/surfacepro3_button.c
index 47c6d000465a..0e2c7dfafd9f 100644
--- a/drivers/platform/x86/surfacepro3_button.c
+++ b/drivers/platform/x86/surfacepro3_button.c
@@ -20,6 +20,12 @@
#define SURFACE_BUTTON_OBJ_NAME "VGBI"
#define SURFACE_BUTTON_DEVICE_NAME "Surface Pro 3/4 Buttons"

+#define MSHW0040_DSM_REVISION 0x01
+#define MSHW0040_DSM_GET_OMPR 0x02 // get OEM Platform Revision
+static const guid_t MSHW0040_DSM_UUID =
+ GUID_INIT(0x6fd05c69, 0xcde3, 0x49f4, 0x95, 0xed, 0xab, 0x16, 0x65,
+ 0x49, 0x80, 0x35);
+
#define SURFACE_BUTTON_NOTIFY_TABLET_MODE 0xc8

#define SURFACE_BUTTON_NOTIFY_PRESS_POWER 0xc6
@@ -142,6 +148,34 @@ static int surface_button_resume(struct device *dev)
}
#endif

+/*
+ * Surface Pro 4 and Surface Book 2 / Surface Pro 2017 use the same device
+ * ID (MSHW0040) for the power/volume buttons. Make sure this is the right
+ * device by checking for the _DSM method and OEM Platform Revision.
+ */
+static int surface_button_check_MSHW0040(struct acpi_device *dev)
+{
+ acpi_handle handle = dev->handle;
+ union acpi_object *result;
+ u64 oem_platform_rev = 0;
+
+ // get OEM platform revision
+ result = acpi_evaluate_dsm_typed(handle, &MSHW0040_DSM_UUID,
+ MSHW0040_DSM_REVISION,
+ MSHW0040_DSM_GET_OMPR,
+ NULL, ACPI_TYPE_INTEGER);
+
+ if (result) {
+ oem_platform_rev = result->integer.value;
+ ACPI_FREE(result);
+ }
+
+ dev_dbg(&dev->dev, "OEM Platform Revision %llu\n", oem_platform_rev);
+
+ return oem_platform_rev == 0 ? 0 : -ENODEV;
+}
+
+
static int surface_button_add(struct acpi_device *device)
{
struct surface_button *button;
@@ -154,6 +188,10 @@ static int surface_button_add(struct acpi_device *device)
strlen(SURFACE_BUTTON_OBJ_NAME)))
return -ENODEV;

+ error = surface_button_check_MSHW0040(device);
+ if (error)
+ return error;
+
button = kzalloc(sizeof(struct surface_button), GFP_KERNEL);
if (!button)
return -ENOMEM;
--
2.22.0