1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_sbi.c b/drivers/gpu/drm/i915/intel_sbi.c
new file mode 100644
index 000000000000..5ba8490a31e6
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_sbi.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2013-2021 Intel Corporation
+ *
+ * LPT/WPT IOSF sideband.
+ */
+
+#include "i915_drv.h"
+#include "intel_sbi.h"
+
+/* SBI access */
+static int intel_sbi_rw(struct drm_i915_private *i915, u16 reg,
+			enum intel_sbi_destination destination,
+			u32 *val, bool is_read)
+{
+	struct intel_uncore *uncore = &i915->uncore;
+	u32 cmd;
+
+	lockdep_assert_held(&i915->sb_lock);
+
+	if (intel_wait_for_register_fw(uncore,
+				       SBI_CTL_STAT, SBI_BUSY, 0,
+				       100)) {
+		drm_err(&i915->drm,
+			"timeout waiting for SBI to become ready\n");
+		return -EBUSY;
+	}
+
+	intel_uncore_write_fw(uncore, SBI_ADDR, (u32)reg << 16);
+	intel_uncore_write_fw(uncore, SBI_DATA, is_read ? 0 : *val);
+
+	if (destination == SBI_ICLK)
+		cmd = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRRD;
+	else
+		cmd = SBI_CTL_DEST_MPHY | SBI_CTL_OP_IORD;
+	if (!is_read)
+		cmd |= BIT(8);
+	intel_uncore_write_fw(uncore, SBI_CTL_STAT, cmd | SBI_BUSY);
+
+	if (__intel_wait_for_register_fw(uncore,
+					 SBI_CTL_STAT, SBI_BUSY, 0,
+					 100, 100, &cmd)) {
+		drm_err(&i915->drm,
+			"timeout waiting for SBI to complete read\n");
+		return -ETIMEDOUT;
+	}
+
+	if (cmd & SBI_RESPONSE_FAIL) {
+		drm_err(&i915->drm, "error during SBI read of reg %x\n", reg);
+		return -ENXIO;
+	}
+
+	if (is_read)
+		*val = intel_uncore_read_fw(uncore, SBI_DATA);
+
+	return 0;
+}
+
+u32 intel_sbi_read(struct drm_i915_private *i915, u16 reg,
+		   enum intel_sbi_destination destination)
+{
+	u32 result = 0;
+
+	intel_sbi_rw(i915, reg, destination, &result, true);
+
+	return result;
+}
+
+void intel_sbi_write(struct drm_i915_private *i915, u16 reg, u32 value,
+		     enum intel_sbi_destination destination)
+{
+	intel_sbi_rw(i915, reg, destination, &value, false);
+}