1 files changed, 106 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_step.c b/drivers/gpu/drm/i915/intel_step.c
new file mode 100644
index 000000000000..4d71547a5b83
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_step.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020,2021 Intel Corporation
+ */
+
+#include "i915_drv.h"
+#include "intel_step.h"
+
+/*
+ * KBL revision ID ordering is bizarre; higher revision ID's map to lower
+ * steppings in some cases.  So rather than test against the revision ID
+ * directly, let's map that into our own range of increasing ID's that we
+ * can test against in a regular manner.
+ */
+
+
+/* FIXME: what about REVID_E0 */
+static const struct intel_step_info kbl_revids[] = {
+	[0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
+	[1] = { .gt_step = STEP_B0, .display_step = STEP_B0 },
+	[2] = { .gt_step = STEP_C0, .display_step = STEP_B0 },
+	[3] = { .gt_step = STEP_D0, .display_step = STEP_B0 },
+	[4] = { .gt_step = STEP_F0, .display_step = STEP_C0 },
+	[5] = { .gt_step = STEP_C0, .display_step = STEP_B1 },
+	[6] = { .gt_step = STEP_D1, .display_step = STEP_B1 },
+	[7] = { .gt_step = STEP_G0, .display_step = STEP_C0 },
+};
+
+static const struct intel_step_info tgl_uy_revid_step_tbl[] = {
+	[0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
+	[1] = { .gt_step = STEP_B0, .display_step = STEP_C0 },
+	[2] = { .gt_step = STEP_B1, .display_step = STEP_C0 },
+	[3] = { .gt_step = STEP_C0, .display_step = STEP_D0 },
+};
+
+/* Same GT stepping between tgl_uy_revids and tgl_revids don't mean the same HW */
+static const struct intel_step_info tgl_revid_step_tbl[] = {
+	[0] = { .gt_step = STEP_A0, .display_step = STEP_B0 },
+	[1] = { .gt_step = STEP_B0, .display_step = STEP_D0 },
+};
+
+static const struct intel_step_info adls_revid_step_tbl[] = {
+	[0x0] = { .gt_step = STEP_A0, .display_step = STEP_A0 },
+	[0x1] = { .gt_step = STEP_A0, .display_step = STEP_A2 },
+	[0x4] = { .gt_step = STEP_B0, .display_step = STEP_B0 },
+	[0x8] = { .gt_step = STEP_C0, .display_step = STEP_B0 },
+	[0xC] = { .gt_step = STEP_D0, .display_step = STEP_C0 },
+};
+
+void intel_step_init(struct drm_i915_private *i915)
+{
+	const struct intel_step_info *revids = NULL;
+	int size = 0;
+	int revid = INTEL_REVID(i915);
+	struct intel_step_info step = {};
+
+	if (IS_ALDERLAKE_S(i915)) {
+		revids = adls_revid_step_tbl;
+		size = ARRAY_SIZE(adls_revid_step_tbl);
+	} else if (IS_TGL_U(i915) || IS_TGL_Y(i915)) {
+		revids = tgl_uy_revid_step_tbl;
+		size = ARRAY_SIZE(tgl_uy_revid_step_tbl);
+	} else if (IS_TIGERLAKE(i915)) {
+		revids = tgl_revid_step_tbl;
+		size = ARRAY_SIZE(tgl_revid_step_tbl);
+	} else if (IS_KABYLAKE(i915)) {
+		revids = kbl_revids;
+		size = ARRAY_SIZE(kbl_revids);
+	}
+
+	/* Not using the stepping scheme for the platform yet. */
+	if (!revids)
+		return;
+
+	if (revid < size && revids[revid].gt_step != STEP_NONE) {
+		step = revids[revid];
+	} else {
+		drm_warn(&i915->drm, "Unknown revid 0x%02x\n", revid);
+
+		/*
+		 * If we hit a gap in the revid array, use the information for
+		 * the next revid.
+		 *
+		 * This may be wrong in all sorts of ways, especially if the
+		 * steppings in the array are not monotonically increasing, but
+		 * it's better than defaulting to 0.
+		 */
+		while (revid < size && revids[revid].gt_step == STEP_NONE)
+			revid++;
+
+		if (revid < size) {
+			drm_dbg(&i915->drm, "Using steppings for revid 0x%02x\n",
+				revid);
+			step = revids[revid];
+		} else {
+			drm_dbg(&i915->drm, "Using future steppings\n");
+			step.gt_step = STEP_FUTURE;
+			step.display_step = STEP_FUTURE;
+		}
+	}
+
+	if (drm_WARN_ON(&i915->drm, step.gt_step == STEP_NONE))
+		return;
+
+	RUNTIME_INFO(i915)->step = step;
+}