1 files changed, 111 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_freq.c b/drivers/gpu/drm/i915/i915_freq.c
new file mode 100644
index 000000000000..9bdaea34aef9
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_freq.c
@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: MIT
+/* Copyright © 2025 Intel Corporation */
+
+#include <drm/drm_print.h>
+
+#include "i915_drv.h"
+#include "i915_freq.h"
+#include "intel_mchbar_regs.h"
+
+unsigned int i9xx_fsb_freq(struct drm_i915_private *i915)
+{
+	u32 fsb;
+
+	/*
+	 * Note that this only reads the state of the FSB
+	 * straps, not the actual FSB frequency. Some BIOSen
+	 * let you configure each independently. Ideally we'd
+	 * read out the actual FSB frequency but sadly we
+	 * don't know which registers have that information,
+	 * and all the relevant docs have gone to bit heaven :(
+	 */
+	fsb = intel_uncore_read(&i915->uncore, CLKCFG) & CLKCFG_FSB_MASK;
+
+	if (IS_PINEVIEW(i915) || IS_MOBILE(i915)) {
+		switch (fsb) {
+		case CLKCFG_FSB_400:
+			return 400000;
+		case CLKCFG_FSB_533:
+			return 533333;
+		case CLKCFG_FSB_667:
+			return 666667;
+		case CLKCFG_FSB_800:
+			return 800000;
+		case CLKCFG_FSB_1067:
+			return 1066667;
+		case CLKCFG_FSB_1333:
+			return 1333333;
+		default:
+			MISSING_CASE(fsb);
+			return 1333333;
+		}
+	} else {
+		switch (fsb) {
+		case CLKCFG_FSB_400_ALT:
+			return 400000;
+		case CLKCFG_FSB_533:
+			return 533333;
+		case CLKCFG_FSB_667:
+			return 666667;
+		case CLKCFG_FSB_800:
+			return 800000;
+		case CLKCFG_FSB_1067_ALT:
+			return 1066667;
+		case CLKCFG_FSB_1333_ALT:
+			return 1333333;
+		case CLKCFG_FSB_1600_ALT:
+			return 1600000;
+		default:
+			MISSING_CASE(fsb);
+			return 1333333;
+		}
+	}
+}
+
+unsigned int ilk_fsb_freq(struct drm_i915_private *i915)
+{
+	u16 fsb;
+
+	fsb = intel_uncore_read16(&i915->uncore, CSIPLL0) & 0x3ff;
+
+	switch (fsb) {
+	case 0x00c:
+		return 3200000;
+	case 0x00e:
+		return 3733333;
+	case 0x010:
+		return 4266667;
+	case 0x012:
+		return 4800000;
+	case 0x014:
+		return 5333333;
+	case 0x016:
+		return 5866667;
+	case 0x018:
+		return 6400000;
+	default:
+		drm_dbg(&i915->drm, "unknown fsb frequency 0x%04x\n", fsb);
+		return 0;
+	}
+}
+
+unsigned int ilk_mem_freq(struct drm_i915_private *i915)
+{
+	u16 ddrpll;
+
+	ddrpll = intel_uncore_read16(&i915->uncore, DDRMPLL1);
+	switch (ddrpll & 0xff) {
+	case 0xc:
+		return 800000;
+	case 0x10:
+		return 1066667;
+	case 0x14:
+		return 1333333;
+	case 0x18:
+		return 1600000;
+	default:
+		drm_dbg(&i915->drm, "unknown memory frequency 0x%02x\n",
+			ddrpll & 0xff);
+		return 0;
+	}
+}