drm/i915: Parse and set stepping for platforms with GMD

Expand the current stepping convention to accommodate the GMD
stepping info. Typically GMD step maps to letter stepping
by "A + step %4" and number to "A + step /4" i.e, GMD step
0 maps to STEP_A0, 1 to _A1, 2 to _A2, 3 to _A3, 4 to STEP_B0...

Future platforms might break this formulae and may require a table
mapping to decode GMD step compatible with the convention.

v2:
 - Pass the updated ip version structure
v3:
 - Skip using GMD to step table(MattR)

Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220916014648.1310346-3-radhakrishna.sripada@intel.com

drivers/gpu/drm/i915/intel_step.c

@@ -135,6 +135,19 @@ static const struct intel_step_info adlp_n_revids[] = {
 	[0x0] = { COMMON_GT_MEDIA_STEP(A0), .display_step = STEP_D0 },
 };
 
+static u8 gmd_to_intel_step(struct drm_i915_private *i915,
+			    struct ip_version *gmd)
+{
+	u8 step = gmd->step + STEP_A0;
+
+	if (step >= STEP_FUTURE) {
+		drm_dbg(&i915->drm, "Using future steppings\n");
+		return STEP_FUTURE;
+	}
+
+	return step;
+}
+
 static void pvc_step_init(struct drm_i915_private *i915, int pci_revid);
 
 void intel_step_init(struct drm_i915_private *i915)
@@ -144,6 +157,18 @@ void intel_step_init(struct drm_i915_private *i915)
 	int revid = INTEL_REVID(i915);
 	struct intel_step_info step = {};
 
+	if (HAS_GMD_ID(i915)) {
+		step.graphics_step = gmd_to_intel_step(i915,
+						       &RUNTIME_INFO(i915)->graphics.ip);
+		step.media_step = gmd_to_intel_step(i915,
+						    &RUNTIME_INFO(i915)->media.ip);
+		step.display_step = gmd_to_intel_step(i915,
+						      &RUNTIME_INFO(i915)->display.ip);
+		RUNTIME_INFO(i915)->step = step;
+
+		return;
+	}
+
 	if (IS_PONTEVECCHIO(i915)) {
 		pvc_step_init(i915, revid);
 		return;

drivers/gpu/drm/i915/intel_step.h

@@ -11,6 +11,10 @@
 struct drm_i915_private;
 
 struct intel_step_info {
+	/*
+	 * It is expected to have 4 number steps per letter. Deviation from
+	 * the expectation breaks gmd_to_intel_step().
+	 */
 	u8 graphics_step;	/* Represents the compute tile on Xe_HPC */
 	u8 display_step;
 	u8 media_step;
@@ -23,21 +27,43 @@ struct intel_step_info {
 	func(A0)			\
 	func(A1)			\
 	func(A2)			\
+	func(A3)			\
 	func(B0)			\
 	func(B1)			\
 	func(B2)			\
 	func(B3)			\
 	func(C0)			\
 	func(C1)			\
+	func(C2)			\
+	func(C3)			\
 	func(D0)			\
 	func(D1)			\
+	func(D2)			\
+	func(D3)			\
 	func(E0)			\
+	func(E1)			\
+	func(E2)			\
+	func(E3)			\
 	func(F0)			\
+	func(F1)			\
+	func(F2)			\
+	func(F3)			\
 	func(G0)			\
+	func(G1)			\
+	func(G2)			\
+	func(G3)			\
 	func(H0)			\
+	func(H1)			\
+	func(H2)			\
+	func(H3)			\
 	func(I0)			\
 	func(I1)			\
-	func(J0)
+	func(I2)			\
+	func(I3)			\
+	func(J0)			\
+	func(J1)			\
+	func(J2)			\
+	func(J3)
 
 /*
  * Symbolic steppings that do not match the hardware. These are valid both as gt