drm/i915/huc: Unified css_header struct for GuC and HuC

HuC firmware css header has almost exactly same definition as GuC
firmware except for the sw_version. Also, add a new member fw_type
into intel_uc_fw to indicate what kind of fw it is. So, the loader
will pull right sw_version from header.

v2: rebased on-top of drm-intel-nightly
v3: rebased. Rename device_id to guc_branch_client_version,
make guc_sw_version a union. <Jeff Mcgee>. Put UC_FW_TYPE_GUC
and UC_FW_TYPE_HUC into an enum.
v4: rebased on top of drm-tip.Update dev to dev_priv in
intel_uc_fw_fetch.
v5: rebased. Add INTEL_ prefix to an enum. Add fw_type declaration
from patch 1.Combine two different unions for huc and guc version,
reserved etc into one union with two structs.
v6: rebased. Change fw_type to enum.
v7: rebased. Rename the enum fw_type to intel_uc_fw_type.

Cc: Michal Wajdeczko <michal.wajdeczko.@intel.com>
Tested-by: Xiang Haihao <haihao.xiang@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Alex Dai <yu.dai@intel.com>
Signed-off-by: Peter Antoine <peter.antoine@intel.com>
Reviewed-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1484356631-16139-3-git-send-email-anusha.srivatsa@intel.com
diff --git a/drivers/gpu/drm/i915/intel_guc_fwif.h b/drivers/gpu/drm/i915/intel_guc_fwif.h
index 3202b32..ed1ab40 100644
--- a/drivers/gpu/drm/i915/intel_guc_fwif.h
+++ b/drivers/gpu/drm/i915/intel_guc_fwif.h
@@ -145,7 +145,7 @@
  * The GuC firmware layout looks like this:
  *
  *     +-------------------------------+
- *     |        guc_css_header         |
+ *     |         uc_css_header         |
  *     |                               |
  *     | contains major/minor version  |
  *     +-------------------------------+
@@ -172,9 +172,16 @@
  * 3. Length info of each component can be found in header, in dwords.
  * 4. Modulus and exponent key are not required by driver. They may not appear
  *    in fw. So driver will load a truncated firmware in this case.
+ *
+ * HuC firmware layout is same as GuC firmware.
+ *
+ * HuC firmware css header is different. However, the only difference is where
+ * the version information is saved. The uc_css_header is unified to support
+ * both. Driver should get HuC version from uc_css_header.huc_sw_version, while
+ * uc_css_header.guc_sw_version for GuC.
  */
 
-struct guc_css_header {
+struct uc_css_header {
 	uint32_t module_type;
 	/* header_size includes all non-uCode bits, including css_header, rsa
 	 * key, modulus key and exponent data. */
@@ -205,8 +212,16 @@ struct guc_css_header {
 
 	char username[8];
 	char buildnumber[12];
-	uint32_t device_id;
-	uint32_t guc_sw_version;
+	union {
+		struct {
+			uint32_t branch_client_version;
+			uint32_t sw_version;
+	} guc;
+		struct {
+			uint32_t sw_version;
+			uint32_t reserved;
+	} huc;
+	};
 	uint32_t prod_preprod_fw;
 	uint32_t reserved[12];
 	uint32_t header_info;