drm/i915/get_params: Add HuC status to getparams

This patch will allow for getparams to return the status of the HuC.
As the HuC has to be validated by the GuC this patch uses the validated
status to show when the HuC is loaded and ready for use. You cannot use
the loaded status as with the GuC as the HuC is verified after it is
loaded and is not usable until it is verified.

v2: removed the forewakes as the registers are already force-woken.
     (T.Ursulin)
v3: rebased on top of drm-tip. Removed any reference to intel_huc.h
v4: rebased. Rename I915_PARAM_HAS_HUC to I915_PARAM_HUC_STATUS.
Remove intel_is_huc_valid() since it is used only in one place.
Put the case of I915_PARAM_HAS_HUC() in the right place.
v5: rebased. Add a comment to specify that I915_READ(reg)
does not read garbage value. The register HUC_STATUS2 is force
woken and no rpm is needed.

Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Peter Antoine <peter.antoine@intel.com>
Reviewed-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1484755558-1234-6-git-send-email-anusha.srivatsa@intel.com

drivers/gpu/drm/i915/i915_drv.c

@@ -49,6 +49,7 @@
 #include "i915_trace.h"
 #include "i915_vgpu.h"
 #include "intel_drv.h"
+#include "intel_uc.h"
 
 static struct drm_driver driver;
 
@@ -315,6 +316,12 @@ static int i915_getparam(struct drm_device *dev, void *data,
 	case I915_PARAM_MIN_EU_IN_POOL:
 		value = INTEL_INFO(dev_priv)->sseu.min_eu_in_pool;
 		break;
+	case I915_PARAM_HUC_STATUS:
+		/* The register is already force-woken. We dont need
+		 * any rpm here
+		 */
+		value = I915_READ(HUC_STATUS2) & HUC_FW_VERIFIED;
+		break;
 	case I915_PARAM_MMAP_GTT_VERSION:
 		/* Though we've started our numbering from 1, and so class all
 		 * earlier versions as 0, in effect their value is undefined as

include/uapi/drm/i915_drm.h

@@ -395,6 +395,7 @@ typedef struct drm_i915_irq_wait {
  * priorities and the driver will attempt to execute batches in priority order.
  */
 #define I915_PARAM_HAS_SCHEDULER	 41
+#define I915_PARAM_HUC_STATUS		 42
 
 typedef struct drm_i915_getparam {
 	__s32 param;