[Intel-gfx] [PATCH 09/15] drm/i915/gt: Move multicast register handling to a dedicated file

[Matt Roper <matthew.d.roper@intel.com>]

Handling of multicast/replicated registers is spread across intel_gt.c
and intel_uncore.c today.  As multicast handling and the related
steering logic gets more complicated with the addition of new platforms
and new rules it makes sense to centralize it all in one place.

For now the existing functions have been moved to the new .c/.h as-is.
Function renames and updates to operate in a more consistent manner will
be done in subsequent patches.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
---
 drivers/gpu/drm/i915/Makefile               |   1 +
 drivers/gpu/drm/i915/gem/i915_gem_stolen.c  |   1 +
 drivers/gpu/drm/i915/gt/intel_engine_cs.c   |   1 +
 drivers/gpu/drm/i915/gt/intel_gt.c          | 262 +------------
 drivers/gpu/drm/i915/gt/intel_gt.h          |  15 -
 drivers/gpu/drm/i915/gt/intel_gt_debugfs.c  |   1 +
 drivers/gpu/drm/i915/gt/intel_gt_mcr.c      | 412 ++++++++++++++++++++
 drivers/gpu/drm/i915/gt/intel_gt_mcr.h      |  37 ++
 drivers/gpu/drm/i915/gt/intel_region_lmem.c |   1 +
 drivers/gpu/drm/i915/gt/intel_workarounds.c |   1 +
 drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c  |   1 +
 drivers/gpu/drm/i915/intel_uncore.c         | 112 ------
 drivers/gpu/drm/i915/intel_uncore.h         |   8 -
 13 files changed, 458 insertions(+), 395 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/gt/intel_gt_mcr.c
 create mode 100644 drivers/gpu/drm/i915/gt/intel_gt_mcr.h

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index c1d5540f6052..b2df1ad6729e 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -101,6 +101,7 @@ gt-y += \
 	gt/intel_gt_debugfs.o \
 	gt/intel_gt_engines_debugfs.o \
 	gt/intel_gt_irq.o \
+	gt/intel_gt_mcr.o \
 	gt/intel_gt_pm.o \
 	gt/intel_gt_pm_debugfs.o \
 	gt/intel_gt_pm_irq.o \
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
index a10d857dfd9b..81604af8b2c2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
@@ -13,6 +13,7 @@
 #include "gem/i915_gem_lmem.h"
 #include "gem/i915_gem_region.h"
 #include "gt/intel_gt.h"
+#include "gt/intel_gt_mcr.h"
 #include "gt/intel_gt_regs.h"
 #include "gt/intel_region_lmem.h"
 #include "i915_drv.h"
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index ad9e7e55ce17..7e6bd8465ed6 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -21,6 +21,7 @@
 #include "intel_engine_user.h"
 #include "intel_execlists_submission.h"
 #include "intel_gt.h"
+#include "intel_gt_mcr.h"
 #include "intel_gt_requests.h"
 #include "intel_gt_pm.h"
 #include "intel_lrc.h"
diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
index 1992325c2895..59c1ab591b86 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -17,6 +17,7 @@
 #include "intel_gt_buffer_pool.h"
 #include "intel_gt_clock_utils.h"
 #include "intel_gt_debugfs.h"
+#include "intel_gt_mcr.h"
 #include "intel_gt_pm.h"
 #include "intel_gt_regs.h"
 #include "intel_gt_requests.h"
@@ -102,78 +103,13 @@ int intel_gt_assign_ggtt(struct intel_gt *gt)
 	return gt->ggtt ? 0 : -ENOMEM;
 }
 
-static const char * const intel_steering_types[] = {
-	"L3BANK",
-	"MSLICE",
-	"LNCF",
-};
-
-static const struct intel_mmio_range icl_l3bank_steering_table[] = {
-	{ 0x00B100, 0x00B3FF },
-	{},
-};
-
-static const struct intel_mmio_range xehpsdv_mslice_steering_table[] = {
-	{ 0x004000, 0x004AFF },
-	{ 0x00C800, 0x00CFFF },
-	{ 0x00DD00, 0x00DDFF },
-	{ 0x00E900, 0x00FFFF }, /* 0xEA00 - OxEFFF is unused */
-	{},
-};
-
-static const struct intel_mmio_range xehpsdv_lncf_steering_table[] = {
-	{ 0x00B000, 0x00B0FF },
-	{ 0x00D800, 0x00D8FF },
-	{},
-};
-
-static const struct intel_mmio_range dg2_lncf_steering_table[] = {
-	{ 0x00B000, 0x00B0FF },
-	{ 0x00D880, 0x00D8FF },
-	{},
-};
-
-static u16 slicemask(struct intel_gt *gt, int count)
-{
-	u64 dss_mask = intel_sseu_get_subslices(&gt->info.sseu, 0);
-
-	return intel_slicemask_from_dssmask(dss_mask, count);
-}
-
 int intel_gt_init_mmio(struct intel_gt *gt)
 {
-	struct drm_i915_private *i915 = gt->i915;
-
 	intel_gt_init_clock_frequency(gt);
 
 	intel_uc_init_mmio(&gt->uc);
 	intel_sseu_info_init(gt);
-
-	/*
-	 * An mslice is unavailable only if both the meml3 for the slice is
-	 * disabled *and* all of the DSS in the slice (quadrant) are disabled.
-	 */
-	if (HAS_MSLICES(i915))
-		gt->info.mslice_mask =
-			slicemask(gt, GEN_DSS_PER_MSLICE) |
-			(intel_uncore_read(gt->uncore, GEN10_MIRROR_FUSE3) &
-			 GEN12_MEML3_EN_MASK);
-
-	if (IS_DG2(i915)) {
-		gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
-		gt->steering_table[LNCF] = dg2_lncf_steering_table;
-	} else if (IS_XEHPSDV(i915)) {
-		gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
-		gt->steering_table[LNCF] = xehpsdv_lncf_steering_table;
-	} else if (GRAPHICS_VER(i915) >= 11 &&
-		   GRAPHICS_VER_FULL(i915) < IP_VER(12, 50)) {
-		gt->steering_table[L3BANK] = icl_l3bank_steering_table;
-		gt->info.l3bank_mask =
-			~intel_uncore_read(gt->uncore, GEN10_MIRROR_FUSE3) &
-			GEN10_L3BANK_MASK;
-	} else if (HAS_MSLICES(i915)) {
-		MISSING_CASE(INTEL_INFO(i915)->platform);
-	}
+	intel_gt_mcr_init(gt);
 
 	return intel_engines_init_mmio(gt);
 }
@@ -873,200 +809,6 @@ void intel_gt_driver_late_release_all(struct drm_i915_private *i915)
 	}
 }
 
-/**
- * intel_gt_reg_needs_read_steering - determine whether a register read
- *     requires explicit steering
- * @gt: GT structure
- * @reg: the register to check steering requirements for
- * @type: type of multicast steering to check
- *
- * Determines whether @reg needs explicit steering of a specific type for
- * reads.
- *
- * Returns false if @reg does not belong to a register range of the given
- * steering type, or if the default (subslice-based) steering IDs are suitable
- * for @type steering too.
- */
-static bool intel_gt_reg_needs_read_steering(struct intel_gt *gt,
-					     i915_reg_t reg,
-					     enum intel_steering_type type)
-{
-	const u32 offset = i915_mmio_reg_offset(reg);
-	const struct intel_mmio_range *entry;
-
-	if (likely(!intel_gt_needs_read_steering(gt, type)))
-		return false;
-
-	for (entry = gt->steering_table[type]; entry->end; entry++) {
-		if (offset >= entry->start && offset <= entry->end)
-			return true;
-	}
-
-	return false;
-}
-
-/**
- * intel_gt_get_valid_steering - determines valid IDs for a class of MCR steering
- * @gt: GT structure
- * @type: multicast register type
- * @sliceid: Slice ID returned
- * @subsliceid: Subslice ID returned
- *
- * Determines sliceid and subsliceid values that will steer reads
- * of a specific multicast register class to a valid value.
- */
-static void intel_gt_get_valid_steering(struct intel_gt *gt,
-					enum intel_steering_type type,
-					u8 *sliceid, u8 *subsliceid)
-{
-	switch (type) {
-	case L3BANK:
-		GEM_DEBUG_WARN_ON(!gt->info.l3bank_mask); /* should be impossible! */
-
-		*sliceid = 0;		/* unused */
-		*subsliceid = __ffs(gt->info.l3bank_mask);
-		break;
-	case MSLICE:
-		GEM_DEBUG_WARN_ON(!gt->info.mslice_mask); /* should be impossible! */
-
-		*sliceid = __ffs(gt->info.mslice_mask);
-		*subsliceid = 0;	/* unused */
-		break;
-	case LNCF:
-		GEM_DEBUG_WARN_ON(!gt->info.mslice_mask); /* should be impossible! */
-
-		/*
-		 * An LNCF is always present if its mslice is present, so we
-		 * can safely just steer to LNCF 0 in all cases.
-		 */
-		*sliceid = __ffs(gt->info.mslice_mask) << 1;
-		*subsliceid = 0;	/* unused */
-		break;
-	default:
-		MISSING_CASE(type);
-		*sliceid = 0;
-		*subsliceid = 0;
-	}
-}
-
-/**
- * intel_gt_read_register_fw - reads a GT register with support for multicast
- * @gt: GT structure
- * @reg: register to read
- *
- * This function will read a GT register.  If the register is a multicast
- * register, the read will be steered to a valid instance (i.e., one that
- * isn't fused off or powered down by power gating).
- *
- * Returns the value from a valid instance of @reg.
- */
-u32 intel_gt_read_register_fw(struct intel_gt *gt, i915_reg_t reg)
-{
-	int type;
-	u8 sliceid, subsliceid;
-
-	for (type = 0; type < NUM_STEERING_TYPES; type++) {
-		if (intel_gt_reg_needs_read_steering(gt, reg, type)) {
-			intel_gt_get_valid_steering(gt, type, &sliceid,
-						    &subsliceid);
-			return intel_uncore_read_with_mcr_steering_fw(gt->uncore,
-								      reg,
-								      sliceid,
-								      subsliceid);
-		}
-	}
-
-	return intel_uncore_read_fw(gt->uncore, reg);
-}
-
-/**
- * intel_gt_get_valid_steering_for_reg - get a valid steering for a register
- * @gt: GT structure
- * @reg: register for which the steering is required
- * @sliceid: return variable for slice steering
- * @subsliceid: return variable for subslice steering
- *
- * This function returns a slice/subslice pair that is guaranteed to work for
- * read steering of the given register. Note that a value will be returned even
- * if the register is not replicated and therefore does not actually require
- * steering.
- */
-void intel_gt_get_valid_steering_for_reg(struct intel_gt *gt, i915_reg_t reg,
-					 u8 *sliceid, u8 *subsliceid)
-{
-	int type;
-
-	for (type = 0; type < NUM_STEERING_TYPES; type++) {
-		if (intel_gt_reg_needs_read_steering(gt, reg, type)) {
-			intel_gt_get_valid_steering(gt, type, sliceid,
-						    subsliceid);
-			return;
-		}
-	}
-
-	*sliceid = gt->default_steering.groupid;
-	*subsliceid = gt->default_steering.instanceid;
-}
-
-u32 intel_gt_read_register(struct intel_gt *gt, i915_reg_t reg)
-{
-	int type;
-	u8 sliceid, subsliceid;
-
-	for (type = 0; type < NUM_STEERING_TYPES; type++) {
-		if (intel_gt_reg_needs_read_steering(gt, reg, type)) {
-			intel_gt_get_valid_steering(gt, type, &sliceid,
-						    &subsliceid);
-			return intel_uncore_read_with_mcr_steering(gt->uncore,
-								   reg,
-								   sliceid,
-								   subsliceid);
-		}
-	}
-
-	return intel_uncore_read(gt->uncore, reg);
-}
-
-static void report_steering_type(struct drm_printer *p,
-				 struct intel_gt *gt,
-				 enum intel_steering_type type,
-				 bool dump_table)
-{
-	const struct intel_mmio_range *entry;
-	u8 slice, subslice;
-
-	BUILD_BUG_ON(ARRAY_SIZE(intel_steering_types) != NUM_STEERING_TYPES);
-
-	if (!gt->steering_table[type]) {
-		drm_printf(p, "%s steering: uses default steering\n",
-			   intel_steering_types[type]);
-		return;
-	}
-
-	intel_gt_get_valid_steering(gt, type, &slice, &subslice);
-	drm_printf(p, "%s steering: sliceid=0x%x, subsliceid=0x%x\n",
-		   intel_steering_types[type], slice, subslice);
-
-	if (!dump_table)
-		return;
-
-	for (entry = gt->steering_table[type]; entry->end; entry++)
-		drm_printf(p, "\t0x%06x - 0x%06x\n", entry->start, entry->end);
-}
-
-void intel_gt_report_steering(struct drm_printer *p, struct intel_gt *gt,
-			      bool dump_table)
-{
-	drm_printf(p, "Default steering: sliceid=0x%x, subsliceid=0x%x\n",
-		   gt->default_steering.groupid,
-		   gt->default_steering.instanceid);
-
-	if (HAS_MSLICES(gt->i915)) {
-		report_steering_type(p, gt, MSLICE, dump_table);
-		report_steering_type(p, gt, LNCF, dump_table);
-	}
-}
-
 static int intel_gt_tile_setup(struct intel_gt *gt, phys_addr_t phys_addr)
 {
 	int ret;
diff --git a/drivers/gpu/drm/i915/gt/intel_gt.h b/drivers/gpu/drm/i915/gt/intel_gt.h
index e76168e10a21..0c47d85256d9 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt.h
@@ -81,21 +81,6 @@ static inline bool intel_gt_is_wedged(const struct intel_gt *gt)
 	return unlikely(test_bit(I915_WEDGED, &gt->reset.flags));
 }
 
-static inline bool intel_gt_needs_read_steering(struct intel_gt *gt,
-						enum intel_steering_type type)
-{
-	return gt->steering_table[type];
-}
-
-void intel_gt_get_valid_steering_for_reg(struct intel_gt *gt, i915_reg_t reg,
-					 u8 *sliceid, u8 *subsliceid);
-
-u32 intel_gt_read_register_fw(struct intel_gt *gt, i915_reg_t reg);
-u32 intel_gt_read_register(struct intel_gt *gt, i915_reg_t reg);
-
-void intel_gt_report_steering(struct drm_printer *p, struct intel_gt *gt,
-			      bool dump_table);
-
 int intel_gt_probe_all(struct drm_i915_private *i915);
 int intel_gt_tiles_init(struct drm_i915_private *i915);
 void intel_gt_release_all(struct drm_i915_private *i915);
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_debugfs.c b/drivers/gpu/drm/i915/gt/intel_gt_debugfs.c
index d886fdc2c694..ea07f2bb846f 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_debugfs.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_debugfs.c
@@ -9,6 +9,7 @@
 #include "intel_gt.h"
 #include "intel_gt_debugfs.h"
 #include "intel_gt_engines_debugfs.h"
+#include "intel_gt_mcr.h"
 #include "intel_gt_pm_debugfs.h"
 #include "intel_sseu_debugfs.h"
 #include "pxp/intel_pxp_debugfs.h"
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_mcr.c b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c
new file mode 100644
index 000000000000..21edee03ce0f
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_gt_mcr.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+
+#include "i915_drv.h"
+
+#include "intel_gt_mcr.h"
+#include "intel_gt_regs.h"
+
+/**
+ * DOC: GT Multicast/Replicated (MCR) Register Support
+ *
+ * Some GT registers are designed as "multicast" or "replicated" registers:
+ * multiple instances of the same register share a single MMIO offset.  MCR
+ * registers are generally used when the hardware needs to potentially track
+ * independent values of a register per hardware unit (e.g., per-subslice,
+ * per-L3bank, etc.).  The specific types of replication that exist vary
+ * per-platform.
+ *
+ * MMIO accesses to MCR registers are controlled according to the settings
+ * programmed in the platform's MCR_SELECTOR register(s).  MMIO writes to MCR
+ * registers can be done in either a (i.e., a single write updates all
+ * instances of the register to the same value) or unicast (a write updates only
+ * one specific instance).  Reads of MCR registers always operate in a unicast
+ * manner regardless of how the multicast/unicast bit is set in MCR_SELECTOR.
+ * Selection of a specific MCR instance for unicast operations is referred to
+ * as "steering."
+ *
+ * If MCR register operations are steered toward a hardware unit that is
+ * fused off or currently powered down due to power gating, the MMIO operation
+ * is "terminated" by the hardware.  Terminated read operations will return a
+ * value of zero and terminated unicast write operations will be silently
+ * ignored.
+ */
+
+static const char * const intel_steering_types[] = {
+	"L3BANK",
+	"MSLICE",
+	"LNCF",
+};
+
+static const struct intel_mmio_range icl_l3bank_steering_table[] = {
+	{ 0x00B100, 0x00B3FF },
+	{},
+};
+
+static const struct intel_mmio_range xehpsdv_mslice_steering_table[] = {
+	{ 0x004000, 0x004AFF },
+	{ 0x00C800, 0x00CFFF },
+	{ 0x00DD00, 0x00DDFF },
+	{ 0x00E900, 0x00FFFF }, /* 0xEA00 - OxEFFF is unused */
+	{},
+};
+
+static const struct intel_mmio_range xehpsdv_lncf_steering_table[] = {
+	{ 0x00B000, 0x00B0FF },
+	{ 0x00D800, 0x00D8FF },
+	{},
+};
+
+static const struct intel_mmio_range dg2_lncf_steering_table[] = {
+	{ 0x00B000, 0x00B0FF },
+	{ 0x00D880, 0x00D8FF },
+	{},
+};
+
+static u16 slicemask(struct intel_gt *gt, int count)
+{
+	u64 dss_mask = intel_sseu_get_subslices(&gt->info.sseu, 0);
+
+	return intel_slicemask_from_dssmask(dss_mask, count);
+}
+
+void intel_gt_mcr_init(struct intel_gt *gt)
+{
+	struct drm_i915_private *i915 = gt->i915;
+
+	/*
+	 * An mslice is unavailable only if both the meml3 for the slice is
+	 * disabled *and* all of the DSS in the slice (quadrant) are disabled.
+	 */
+	if (HAS_MSLICES(i915))
+		gt->info.mslice_mask =
+			slicemask(gt, GEN_DSS_PER_MSLICE) |
+			(intel_uncore_read(gt->uncore, GEN10_MIRROR_FUSE3) &
+			 GEN12_MEML3_EN_MASK);
+
+	if (IS_DG2(i915)) {
+		gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
+		gt->steering_table[LNCF] = dg2_lncf_steering_table;
+	} else if (IS_XEHPSDV(i915)) {
+		gt->steering_table[MSLICE] = xehpsdv_mslice_steering_table;
+		gt->steering_table[LNCF] = xehpsdv_lncf_steering_table;
+	} else if (GRAPHICS_VER(i915) >= 11 &&
+		   GRAPHICS_VER_FULL(i915) < IP_VER(12, 50)) {
+		gt->steering_table[L3BANK] = icl_l3bank_steering_table;
+		gt->info.l3bank_mask =
+			~intel_uncore_read(gt->uncore, GEN10_MIRROR_FUSE3) &
+			GEN10_L3BANK_MASK;
+	} else if (HAS_MSLICES(i915)) {
+		MISSING_CASE(INTEL_INFO(i915)->platform);
+	}
+}
+
+/**
+ * uncore_rw_with_mcr_steering_fw - Access a register after programming
+ *				    the MCR selector register.
+ * @uncore: pointer to struct intel_uncore
+ * @reg: register being accessed
+ * @rw_flag: FW_REG_READ for read access or FW_REG_WRITE for write access
+ * @slice: slice number (ignored for multi-cast write)
+ * @subslice: sub-slice number (ignored for multi-cast write)
+ * @value: register value to be written (ignored for read)
+ *
+ * Return: 0 for write access. register value for read access.
+ *
+ * Caller needs to make sure the relevant forcewake wells are up.
+ */
+static u32 uncore_rw_with_mcr_steering_fw(struct intel_uncore *uncore,
+					  i915_reg_t reg, u8 rw_flag,
+					  int slice, int subslice, u32 value)
+{
+	u32 mcr_mask, mcr_ss, mcr, old_mcr, val = 0;
+
+	lockdep_assert_held(&uncore->lock);
+
+	if (GRAPHICS_VER(uncore->i915) >= 11) {
+		mcr_mask = GEN11_MCR_SLICE_MASK | GEN11_MCR_SUBSLICE_MASK;
+		mcr_ss = GEN11_MCR_SLICE(slice) | GEN11_MCR_SUBSLICE(subslice);
+
+		/*
+		 * Wa_22013088509
+		 *
+		 * The setting of the multicast/unicast bit usually wouldn't
+		 * matter for read operations (which always return the value
+		 * from a single register instance regardless of how that bit
+		 * is set), but some platforms have a workaround requiring us
+		 * to remain in multicast mode for reads.  There's no real
+		 * downside to this, so we'll just go ahead and do so on all
+		 * platforms; we'll only clear the multicast bit from the mask
+		 * when exlicitly doing a write operation.
+		 */
+		if (rw_flag == FW_REG_WRITE)
+			mcr_mask |= GEN11_MCR_MULTICAST;
+	} else {
+		mcr_mask = GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK;
+		mcr_ss = GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
+	}
+
+	old_mcr = mcr = intel_uncore_read_fw(uncore, GEN8_MCR_SELECTOR);
+
+	mcr &= ~mcr_mask;
+	mcr |= mcr_ss;
+	intel_uncore_write_fw(uncore, GEN8_MCR_SELECTOR, mcr);
+
+	if (rw_flag == FW_REG_READ)
+		val = intel_uncore_read_fw(uncore, reg);
+	else
+		intel_uncore_write_fw(uncore, reg, value);
+
+	mcr &= ~mcr_mask;
+	mcr |= old_mcr & mcr_mask;
+
+	intel_uncore_write_fw(uncore, GEN8_MCR_SELECTOR, mcr);
+
+	return val;
+}
+
+static u32 uncore_rw_with_mcr_steering(struct intel_uncore *uncore,
+				       i915_reg_t reg, u8 rw_flag,
+				       int slice, int subslice,
+				       u32 value)
+{
+	enum forcewake_domains fw_domains;
+	u32 val;
+
+	fw_domains = intel_uncore_forcewake_for_reg(uncore, reg,
+						    rw_flag);
+	fw_domains |= intel_uncore_forcewake_for_reg(uncore,
+						     GEN8_MCR_SELECTOR,
+						     FW_REG_READ | FW_REG_WRITE);
+
+	spin_lock_irq(&uncore->lock);
+	intel_uncore_forcewake_get__locked(uncore, fw_domains);
+
+	val = uncore_rw_with_mcr_steering_fw(uncore, reg, rw_flag,
+					     slice, subslice, value);
+
+	intel_uncore_forcewake_put__locked(uncore, fw_domains);
+	spin_unlock_irq(&uncore->lock);
+
+	return val;
+}
+
+u32 intel_uncore_read_with_mcr_steering_fw(struct intel_uncore *uncore,
+					   i915_reg_t reg, int slice, int subslice)
+{
+	return uncore_rw_with_mcr_steering_fw(uncore, reg, FW_REG_READ,
+					      slice, subslice, 0);
+}
+
+u32 intel_uncore_read_with_mcr_steering(struct intel_uncore *uncore,
+					i915_reg_t reg, int slice, int subslice)
+{
+	return uncore_rw_with_mcr_steering(uncore, reg, FW_REG_READ,
+					   slice, subslice, 0);
+}
+
+void intel_uncore_write_with_mcr_steering(struct intel_uncore *uncore,
+					  i915_reg_t reg, u32 value,
+					  int slice, int subslice)
+{
+	uncore_rw_with_mcr_steering(uncore, reg, FW_REG_WRITE,
+				    slice, subslice, value);
+}
+
+
+/**
+ * intel_gt_reg_needs_read_steering - determine whether a register read
+ *     requires explicit steering
+ * @gt: GT structure
+ * @reg: the register to check steering requirements for
+ * @type: type of multicast steering to check
+ *
+ * Determines whether @reg needs explicit steering of a specific type for
+ * reads.
+ *
+ * Returns false if @reg does not belong to a register range of the given
+ * steering type, or if the default (subslice-based) steering IDs are suitable
+ * for @type steering too.
+ */
+static bool intel_gt_reg_needs_read_steering(struct intel_gt *gt,
+					     i915_reg_t reg,
+					     enum intel_steering_type type)
+{
+	const u32 offset = i915_mmio_reg_offset(reg);
+	const struct intel_mmio_range *entry;
+
+	if (likely(!intel_gt_needs_read_steering(gt, type)))
+		return false;
+
+	for (entry = gt->steering_table[type]; entry->end; entry++) {
+		if (offset >= entry->start && offset <= entry->end)
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * intel_gt_get_valid_steering - determines valid IDs for a class of MCR steering
+ * @gt: GT structure
+ * @type: multicast register type
+ * @sliceid: Slice ID returned
+ * @subsliceid: Subslice ID returned
+ *
+ * Determines sliceid and subsliceid values that will steer reads
+ * of a specific multicast register class to a valid value.
+ */
+static void intel_gt_get_valid_steering(struct intel_gt *gt,
+					enum intel_steering_type type,
+					u8 *sliceid, u8 *subsliceid)
+{
+	switch (type) {
+	case L3BANK:
+		GEM_DEBUG_WARN_ON(!gt->info.l3bank_mask); /* should be impossible! */
+
+		*sliceid = 0;		/* unused */
+		*subsliceid = __ffs(gt->info.l3bank_mask);
+		break;
+	case MSLICE:
+		GEM_DEBUG_WARN_ON(!gt->info.mslice_mask); /* should be impossible! */
+
+		*sliceid = __ffs(gt->info.mslice_mask);
+		*subsliceid = 0;	/* unused */
+		break;
+	case LNCF:
+		GEM_DEBUG_WARN_ON(!gt->info.mslice_mask); /* should be impossible! */
+
+		/*
+		 * An LNCF is always present if its mslice is present, so we
+		 * can safely just steer to LNCF 0 in all cases.
+		 */
+		*sliceid = __ffs(gt->info.mslice_mask) << 1;
+		*subsliceid = 0;	/* unused */
+		break;
+	default:
+		MISSING_CASE(type);
+		*sliceid = 0;
+		*subsliceid = 0;
+	}
+}
+
+/**
+ * intel_gt_get_valid_steering_for_reg - get a valid steering for a register
+ * @gt: GT structure
+ * @reg: register for which the steering is required
+ * @sliceid: return variable for slice steering
+ * @subsliceid: return variable for subslice steering
+ *
+ * This function returns a slice/subslice pair that is guaranteed to work for
+ * read steering of the given register. Note that a value will be returned even
+ * if the register is not replicated and therefore does not actually require
+ * steering.
+ */
+void intel_gt_get_valid_steering_for_reg(struct intel_gt *gt, i915_reg_t reg,
+					 u8 *sliceid, u8 *subsliceid)
+{
+	int type;
+
+	for (type = 0; type < NUM_STEERING_TYPES; type++) {
+		if (intel_gt_reg_needs_read_steering(gt, reg, type)) {
+			intel_gt_get_valid_steering(gt, type, sliceid,
+						    subsliceid);
+			return;
+		}
+	}
+
+	*sliceid = gt->default_steering.groupid;
+	*subsliceid = gt->default_steering.instanceid;
+}
+
+/**
+ * intel_gt_read_register_fw - reads a GT register with support for multicast
+ * @gt: GT structure
+ * @reg: register to read
+ *
+ * This function will read a GT register.  If the register is a multicast
+ * register, the read will be steered to a valid instance (i.e., one that
+ * isn't fused off or powered down by power gating).
+ *
+ * Returns the value from a valid instance of @reg.
+ */
+u32 intel_gt_read_register_fw(struct intel_gt *gt, i915_reg_t reg)
+{
+	int type;
+	u8 sliceid, subsliceid;
+
+	for (type = 0; type < NUM_STEERING_TYPES; type++) {
+		if (intel_gt_reg_needs_read_steering(gt, reg, type)) {
+			intel_gt_get_valid_steering(gt, type, &sliceid,
+						    &subsliceid);
+			return intel_uncore_read_with_mcr_steering_fw(gt->uncore,
+								      reg,
+								      sliceid,
+								      subsliceid);
+		}
+	}
+
+	return intel_uncore_read_fw(gt->uncore, reg);
+}
+
+u32 intel_gt_read_register(struct intel_gt *gt, i915_reg_t reg)
+{
+	int type;
+	u8 sliceid, subsliceid;
+
+	for (type = 0; type < NUM_STEERING_TYPES; type++) {
+		if (intel_gt_reg_needs_read_steering(gt, reg, type)) {
+			intel_gt_get_valid_steering(gt, type, &sliceid,
+						    &subsliceid);
+			return intel_uncore_read_with_mcr_steering(gt->uncore,
+								   reg,
+								   sliceid,
+								   subsliceid);
+		}
+	}
+
+	return intel_uncore_read(gt->uncore, reg);
+}
+
+static void report_steering_type(struct drm_printer *p,
+				 struct intel_gt *gt,
+				 enum intel_steering_type type,
+				 bool dump_table)
+{
+	const struct intel_mmio_range *entry;
+	u8 slice, subslice;
+
+	BUILD_BUG_ON(ARRAY_SIZE(intel_steering_types) != NUM_STEERING_TYPES);
+
+	if (!gt->steering_table[type]) {
+		drm_printf(p, "%s steering: uses default steering\n",
+			   intel_steering_types[type]);
+		return;
+	}
+
+	intel_gt_get_valid_steering(gt, type, &slice, &subslice);
+	drm_printf(p, "%s steering: sliceid=0x%x, subsliceid=0x%x\n",
+		   intel_steering_types[type], slice, subslice);
+
+	if (!dump_table)
+		return;
+
+	for (entry = gt->steering_table[type]; entry->end; entry++)
+		drm_printf(p, "\t0x%06x - 0x%06x\n", entry->start, entry->end);
+}
+
+void intel_gt_report_steering(struct drm_printer *p, struct intel_gt *gt,
+			      bool dump_table)
+{
+	drm_printf(p, "Default steering: sliceid=0x%x, subsliceid=0x%x\n",
+		   gt->default_steering.groupid,
+		   gt->default_steering.instanceid);
+
+	if (HAS_MSLICES(gt->i915)) {
+		report_steering_type(p, gt, MSLICE, dump_table);
+		report_steering_type(p, gt, LNCF, dump_table);
+	}
+}
+
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_mcr.h b/drivers/gpu/drm/i915/gt/intel_gt_mcr.h
new file mode 100644
index 000000000000..b570c1571243
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_gt_mcr.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+
+#ifndef __INTEL_GT_MCR__
+#define __INTEL_GT_MCR__
+
+#include "intel_gt_types.h"
+
+void intel_gt_mcr_init(struct intel_gt *gt);
+
+u32 intel_uncore_read_with_mcr_steering_fw(struct intel_uncore *uncore,
+					   i915_reg_t reg,
+					   int slice, int subslice);
+u32 intel_uncore_read_with_mcr_steering(struct intel_uncore *uncore,
+					i915_reg_t reg,	int slice, int subslice);
+void intel_uncore_write_with_mcr_steering(struct intel_uncore *uncore,
+					  i915_reg_t reg, u32 value,
+					  int slice, int subslice);
+
+u32 intel_gt_read_register_fw(struct intel_gt *gt, i915_reg_t reg);
+u32 intel_gt_read_register(struct intel_gt *gt, i915_reg_t reg);
+
+static inline bool intel_gt_needs_read_steering(struct intel_gt *gt,
+						enum intel_steering_type type)
+{
+	return gt->steering_table[type];
+}
+
+void intel_gt_get_valid_steering_for_reg(struct intel_gt *gt, i915_reg_t reg,
+					 u8 *sliceid, u8 *subsliceid);
+
+void intel_gt_report_steering(struct drm_printer *p, struct intel_gt *gt,
+			      bool dump_table);
+
+#endif /* __INTEL_GT_MCR__ */
diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
index f5111c0a0060..6e788a5fc85a 100644
--- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
+++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
@@ -12,6 +12,7 @@
 #include "gem/i915_gem_region.h"
 #include "gem/i915_gem_ttm.h"
 #include "gt/intel_gt.h"
+#include "gt/intel_gt_mcr.h"
 #include "gt/intel_gt_regs.h"
 
 static int
diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index 544097c56619..e9bf0d9f50d8 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -9,6 +9,7 @@
 #include "intel_engine_regs.h"
 #include "intel_gpu_commands.h"
 #include "intel_gt.h"
+#include "intel_gt_mcr.h"
 #include "intel_gt_regs.h"
 #include "intel_ring.h"
 #include "intel_workarounds.h"
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
index e8a42d719f96..c63a6bf9e853 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ads.c
@@ -7,6 +7,7 @@
 
 #include "gt/intel_engine_regs.h"
 #include "gt/intel_gt.h"
+#include "gt/intel_gt_mcr.h"
 #include "gt/intel_gt_regs.h"
 #include "gt/intel_lrc.h"
 #include "gt/shmem_utils.h"
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 8b9caaaacc21..8069671d73d6 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -2459,118 +2459,6 @@ intel_uncore_forcewake_for_reg(struct intel_uncore *uncore,
 	return fw_domains;
 }
 
-/**
- * uncore_rw_with_mcr_steering_fw - Access a register after programming
- *				    the MCR selector register.
- * @uncore: pointer to struct intel_uncore
- * @reg: register being accessed
- * @rw_flag: FW_REG_READ for read access or FW_REG_WRITE for write access
- * @slice: slice number (ignored for multi-cast write)
- * @subslice: sub-slice number (ignored for multi-cast write)
- * @value: register value to be written (ignored for read)
- *
- * Return: 0 for write access. register value for read access.
- *
- * Caller needs to make sure the relevant forcewake wells are up.
- */
-static u32 uncore_rw_with_mcr_steering_fw(struct intel_uncore *uncore,
-					  i915_reg_t reg, u8 rw_flag,
-					  int slice, int subslice, u32 value)
-{
-	u32 mcr_mask, mcr_ss, mcr, old_mcr, val = 0;
-
-	lockdep_assert_held(&uncore->lock);
-
-	if (GRAPHICS_VER(uncore->i915) >= 11) {
-		mcr_mask = GEN11_MCR_SLICE_MASK | GEN11_MCR_SUBSLICE_MASK;
-		mcr_ss = GEN11_MCR_SLICE(slice) | GEN11_MCR_SUBSLICE(subslice);
-
-		/*
-		 * Wa_22013088509
-		 *
-		 * The setting of the multicast/unicast bit usually wouldn't
-		 * matter for read operations (which always return the value
-		 * from a single register instance regardless of how that bit
-		 * is set), but some platforms have a workaround requiring us
-		 * to remain in multicast mode for reads.  There's no real
-		 * downside to this, so we'll just go ahead and do so on all
-		 * platforms; we'll only clear the multicast bit from the mask
-		 * when exlicitly doing a write operation.
-		 */
-		if (rw_flag == FW_REG_WRITE)
-			mcr_mask |= GEN11_MCR_MULTICAST;
-	} else {
-		mcr_mask = GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK;
-		mcr_ss = GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
-	}
-
-	old_mcr = mcr = intel_uncore_read_fw(uncore, GEN8_MCR_SELECTOR);
-
-	mcr &= ~mcr_mask;
-	mcr |= mcr_ss;
-	intel_uncore_write_fw(uncore, GEN8_MCR_SELECTOR, mcr);
-
-	if (rw_flag == FW_REG_READ)
-		val = intel_uncore_read_fw(uncore, reg);
-	else
-		intel_uncore_write_fw(uncore, reg, value);
-
-	mcr &= ~mcr_mask;
-	mcr |= old_mcr & mcr_mask;
-
-	intel_uncore_write_fw(uncore, GEN8_MCR_SELECTOR, mcr);
-
-	return val;
-}
-
-static u32 uncore_rw_with_mcr_steering(struct intel_uncore *uncore,
-				       i915_reg_t reg, u8 rw_flag,
-				       int slice, int subslice,
-				       u32 value)
-{
-	enum forcewake_domains fw_domains;
-	u32 val;
-
-	fw_domains = intel_uncore_forcewake_for_reg(uncore, reg,
-						    rw_flag);
-	fw_domains |= intel_uncore_forcewake_for_reg(uncore,
-						     GEN8_MCR_SELECTOR,
-						     FW_REG_READ | FW_REG_WRITE);
-
-	spin_lock_irq(&uncore->lock);
-	intel_uncore_forcewake_get__locked(uncore, fw_domains);
-
-	val = uncore_rw_with_mcr_steering_fw(uncore, reg, rw_flag,
-					     slice, subslice, value);
-
-	intel_uncore_forcewake_put__locked(uncore, fw_domains);
-	spin_unlock_irq(&uncore->lock);
-
-	return val;
-}
-
-u32 intel_uncore_read_with_mcr_steering_fw(struct intel_uncore *uncore,
-					   i915_reg_t reg, int slice, int subslice)
-{
-	return uncore_rw_with_mcr_steering_fw(uncore, reg, FW_REG_READ,
-					      slice, subslice, 0);
-}
-
-u32 intel_uncore_read_with_mcr_steering(struct intel_uncore *uncore,
-					i915_reg_t reg, int slice, int subslice)
-{
-	return uncore_rw_with_mcr_steering(uncore, reg, FW_REG_READ,
-					   slice, subslice, 0);
-}
-
-void intel_uncore_write_with_mcr_steering(struct intel_uncore *uncore,
-					  i915_reg_t reg, u32 value,
-					  int slice, int subslice)
-{
-	uncore_rw_with_mcr_steering(uncore, reg, FW_REG_WRITE,
-				    slice, subslice, value);
-}
-
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_uncore.c"
 #include "selftests/intel_uncore.c"
diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
index 52fe3d89dd2b..b1fa912a65e7 100644
--- a/drivers/gpu/drm/i915/intel_uncore.h
+++ b/drivers/gpu/drm/i915/intel_uncore.h
@@ -210,14 +210,6 @@ intel_uncore_has_fifo(const struct intel_uncore *uncore)
 	return uncore->flags & UNCORE_HAS_FIFO;
 }
 
-u32 intel_uncore_read_with_mcr_steering_fw(struct intel_uncore *uncore,
-					   i915_reg_t reg,
-					   int slice, int subslice);
-u32 intel_uncore_read_with_mcr_steering(struct intel_uncore *uncore,
-					i915_reg_t reg,	int slice, int subslice);
-void intel_uncore_write_with_mcr_steering(struct intel_uncore *uncore,
-					  i915_reg_t reg, u32 value,
-					  int slice, int subslice);
 void
 intel_uncore_mmio_debug_init_early(struct intel_uncore_mmio_debug *mmio_debug);
 void intel_uncore_init_early(struct intel_uncore *uncore,
-- 
2.34.1