drm/xe/rtp: Add match helper for gslice fused off

Add match helper to detect when the first gslice is fused off, as needed
by future workarounds.

v2:
  - Add warning if called on a platform without geometry pipeline
    (Matt Roper)
  - Hardcode 4 as the number of gslices, which matches all the currently
    supported platforms. PVC doesn't have geometry pipeline and
    shouldn't use this function (Matt Roper)

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230314003012.2600353-2-lucas.demarchi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_rtp.c

@@ -8,6 +8,7 @@
 #include <drm/xe_drm.h>
 
 #include "xe_gt.h"
+#include "xe_gt_topology.h"
 #include "xe_macros.h"
 #include "xe_reg_sr.h"
 
@@ -170,3 +171,18 @@ bool xe_rtp_match_first_render_or_compute(const struct xe_gt *gt,
 	return render_compute_mask &&
 		hwe->engine_id == __ffs(render_compute_mask);
 }
+
+bool xe_rtp_match_first_gslice_fused_off(const struct xe_gt *gt,
+					 const struct xe_hw_engine *hwe)
+{
+	unsigned int dss_per_gslice = 4;
+	unsigned int dss;
+
+	if (drm_WARN(&gt_to_xe(gt)->drm, !gt->fuse_topo.g_dss_mask,
+		     "Checking gslice for platform without geometry pipeline\n"))
+		return false;
+
+	dss = xe_dss_mask_group_ffs(gt->fuse_topo.g_dss_mask, 0, 0);
+
+	return dss >= dss_per_gslice;
+}

drivers/gpu/drm/xe/xe_rtp.h

@@ -427,4 +427,15 @@ bool xe_rtp_match_even_instance(const struct xe_gt *gt,
 bool xe_rtp_match_first_render_or_compute(const struct xe_gt *gt,
 					  const struct xe_hw_engine *hwe);
 
+/*
+ * xe_rtp_match_first_gslice_fused_off - Match when first gslice is fused off
+ *
+ * @gt: GT structure
+ * @hwe: Engine instance
+ *
+ * Returns: true if first gslice is fused off, false otherwise.
+ */
+bool xe_rtp_match_first_gslice_fused_off(const struct xe_gt *gt,
+					 const struct xe_hw_engine *hwe);
+
 #endif