drm/amd: add support to check whether the system is set to s3

This will be used to help make decisions on what to do in
misconfigured systems.

v2: squash in semicolon fix from Stephen Rothwell

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: superm1

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1421,9 +1421,11 @@ static inline int amdgpu_acpi_smart_shift_update(struct drm_device *dev,
 #endif
 
 #if defined(CONFIG_ACPI) && defined(CONFIG_SUSPEND)
+bool amdgpu_acpi_is_s3_active(struct amdgpu_device *adev);
 bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev);
 #else
 static inline bool amdgpu_acpi_is_s0ix_active(struct amdgpu_device *adev) { return false; }
+static inline bool amdgpu_acpi_is_s3_active(struct amdgpu_device *adev) { return false; }
 #endif
 
 int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,

drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c

@@ -1032,6 +1032,19 @@ void amdgpu_acpi_detect(void)
 }
 
 #if IS_ENABLED(CONFIG_SUSPEND)
+/**
+ * amdgpu_acpi_is_s3_active
+ *
+ * @adev: amdgpu_device_pointer
+ *
+ * returns true if supported, false if not.
+ */
+bool amdgpu_acpi_is_s3_active(struct amdgpu_device *adev)
+{
+	return !(adev->flags & AMD_IS_APU) ||
+		(pm_suspend_target_state == PM_SUSPEND_MEM);
+}
+
 /**
  * amdgpu_acpi_is_s0ix_active
  *