drm/xe: Introduce a new DRM driver for Intel GPUs

Xe, is a new driver for Intel GPUs that supports both integrated and
discrete platforms starting with Tiger Lake (first Intel Xe Architecture).

The code is at a stage where it is already functional and has experimental
support for multiple platforms starting from Tiger Lake, with initial
support implemented in Mesa (for Iris and Anv, our OpenGL and Vulkan
drivers), as well as in NEO (for OpenCL and Level0).

The new Xe driver leverages a lot from i915.

As for display, the intent is to share the display code with the i915
driver so that there is maximum reuse there. But it is not added
in this patch.

This initial work is a collaboration of many people and unfortunately
the big squashed patch won't fully honor the proper credits. But let's
get some git quick stats so we can at least try to preserve some of the
credits:

Co-developed-by: Matthew Brost <matthew.brost@intel.com>
Co-developed-by: Matthew Auld <matthew.auld@intel.com>
Co-developed-by: Matt Roper <matthew.d.roper@intel.com>
Co-developed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Co-developed-by: Francois Dugast <francois.dugast@intel.com>
Co-developed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Co-developed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Co-developed-by: Philippe Lecluse <philippe.lecluse@intel.com>
Co-developed-by: Nirmoy Das <nirmoy.das@intel.com>
Co-developed-by: Jani Nikula <jani.nikula@intel.com>
Co-developed-by: José Roberto de Souza <jose.souza@intel.com>
Co-developed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Co-developed-by: Dave Airlie <airlied@redhat.com>
Co-developed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Co-developed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Co-developed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>

1 files changed, 552 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c b/drivers/gpu/drm/xe/xe_gt_mcr.c
new file mode 100644
index 000000000000..b69c0d6c6b2f
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_gt_mcr.c
@@ -0,0 +1,552 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+
+#include "xe_gt.h"
+#include "xe_gt_mcr.h"
+#include "xe_gt_topology.h"
+#include "xe_gt_types.h"
+#include "xe_mmio.h"
+
+#include "gt/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.
+ */
+
+enum {
+	MCR_OP_READ,
+	MCR_OP_WRITE
+};
+
+static const struct xe_mmio_range xelp_l3bank_steering_table[] = {
+	{ 0x00B100, 0x00B3FF },
+	{},
+};
+
+/*
+ * Although the bspec lists more "MSLICE" ranges than shown here, some of those
+ * are of a "GAM" subclass that has special rules and doesn't need to be
+ * included here.
+ */
+static const struct xe_mmio_range xehp_mslice_steering_table[] = {
+	{ 0x00DD00, 0x00DDFF },
+	{ 0x00E900, 0x00FFFF }, /* 0xEA00 - OxEFFF is unused */
+	{},
+};
+
+static const struct xe_mmio_range xehp_lncf_steering_table[] = {
+	{ 0x00B000, 0x00B0FF },
+	{ 0x00D880, 0x00D8FF },
+	{},
+};
+
+/*
+ * We have several types of MCR registers where steering to (0,0) will always
+ * provide us with a non-terminated value.  We'll stick them all in the same
+ * table for simplicity.
+ */
+static const struct xe_mmio_range xehpc_instance0_steering_table[] = {
+	{ 0x004000, 0x004AFF },		/* HALF-BSLICE */
+	{ 0x008800, 0x00887F },		/* CC */
+	{ 0x008A80, 0x008AFF },		/* TILEPSMI */
+	{ 0x00B000, 0x00B0FF },		/* HALF-BSLICE */
+	{ 0x00B100, 0x00B3FF },		/* L3BANK */
+	{ 0x00C800, 0x00CFFF },		/* HALF-BSLICE */
+	{ 0x00D800, 0x00D8FF },		/* HALF-BSLICE */
+	{ 0x00DD00, 0x00DDFF },		/* BSLICE */
+	{ 0x00E900, 0x00E9FF },		/* HALF-BSLICE */
+	{ 0x00EC00, 0x00EEFF },		/* HALF-BSLICE */
+	{ 0x00F000, 0x00FFFF },		/* HALF-BSLICE */
+	{ 0x024180, 0x0241FF },		/* HALF-BSLICE */
+	{},
+};
+
+static const struct xe_mmio_range xelpg_instance0_steering_table[] = {
+	{ 0x000B00, 0x000BFF },         /* SQIDI */
+	{ 0x001000, 0x001FFF },         /* SQIDI */
+	{ 0x004000, 0x0048FF },         /* GAM */
+	{ 0x008700, 0x0087FF },         /* SQIDI */
+	{ 0x00B000, 0x00B0FF },         /* NODE */
+	{ 0x00C800, 0x00CFFF },         /* GAM */
+	{ 0x00D880, 0x00D8FF },         /* NODE */
+	{ 0x00DD00, 0x00DDFF },         /* OAAL2 */
+	{},
+};
+
+static const struct xe_mmio_range xelpg_l3bank_steering_table[] = {
+	{ 0x00B100, 0x00B3FF },
+	{},
+};
+
+static const struct xe_mmio_range xelp_dss_steering_table[] = {
+	{ 0x008150, 0x00815F },
+	{ 0x009520, 0x00955F },
+	{ 0x00DE80, 0x00E8FF },
+	{ 0x024A00, 0x024A7F },
+	{},
+};
+
+/* DSS steering is used for GSLICE ranges as well */
+static const struct xe_mmio_range xehp_dss_steering_table[] = {
+	{ 0x005200, 0x0052FF },		/* GSLICE */
+	{ 0x005400, 0x007FFF },		/* GSLICE */
+	{ 0x008140, 0x00815F },		/* GSLICE (0x8140-0x814F), DSS (0x8150-0x815F) */
+	{ 0x008D00, 0x008DFF },		/* DSS */
+	{ 0x0094D0, 0x00955F },		/* GSLICE (0x94D0-0x951F), DSS (0x9520-0x955F) */
+	{ 0x009680, 0x0096FF },		/* DSS */
+	{ 0x00D800, 0x00D87F },		/* GSLICE */
+	{ 0x00DC00, 0x00DCFF },		/* GSLICE */
+	{ 0x00DE80, 0x00E8FF },		/* DSS (0xE000-0xE0FF reserved ) */
+	{ 0x017000, 0x017FFF },		/* GSLICE */
+	{ 0x024A00, 0x024A7F },		/* DSS */
+	{},
+};
+
+/* DSS steering is used for COMPUTE ranges as well */
+static const struct xe_mmio_range xehpc_dss_steering_table[] = {
+	{ 0x008140, 0x00817F },		/* COMPUTE (0x8140-0x814F & 0x8160-0x817F), DSS (0x8150-0x815F) */
+	{ 0x0094D0, 0x00955F },		/* COMPUTE (0x94D0-0x951F), DSS (0x9520-0x955F) */
+	{ 0x009680, 0x0096FF },		/* DSS */
+	{ 0x00DC00, 0x00DCFF },		/* COMPUTE */
+	{ 0x00DE80, 0x00E7FF },		/* DSS (0xDF00-0xE1FF reserved ) */
+	{},
+};
+
+/* DSS steering is used for SLICE ranges as well */
+static const struct xe_mmio_range xelpg_dss_steering_table[] = {
+	{ 0x005200, 0x0052FF },		/* SLICE */
+	{ 0x005500, 0x007FFF },		/* SLICE */
+	{ 0x008140, 0x00815F },		/* SLICE (0x8140-0x814F), DSS (0x8150-0x815F) */
+	{ 0x0094D0, 0x00955F },		/* SLICE (0x94D0-0x951F), DSS (0x9520-0x955F) */
+	{ 0x009680, 0x0096FF },		/* DSS */
+	{ 0x00D800, 0x00D87F },		/* SLICE */
+	{ 0x00DC00, 0x00DCFF },		/* SLICE */
+	{ 0x00DE80, 0x00E8FF },		/* DSS (0xE000-0xE0FF reserved) */
+	{},
+};
+
+static const struct xe_mmio_range xelpmp_oaddrm_steering_table[] = {
+	{ 0x393200, 0x39323F },
+	{ 0x393400, 0x3934FF },
+	{},
+};
+
+/*
+ * DG2 GAM registers are a special case; this table is checked directly in
+ * xe_gt_mcr_get_nonterminated_steering and is not hooked up via
+ * gt->steering[].
+ */
+static const struct xe_mmio_range dg2_gam_ranges[] = {
+	{ 0x004000, 0x004AFF },
+	{ 0x00C800, 0x00CFFF },
+	{ 0x00F000, 0x00FFFF },
+	{},
+};
+
+static void init_steering_l3bank(struct xe_gt *gt)
+{
+	if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 1270) {
+		u32 mslice_mask = REG_FIELD_GET(GEN12_MEML3_EN_MASK,
+						xe_mmio_read32(gt, GEN10_MIRROR_FUSE3.reg));
+		u32 bank_mask = REG_FIELD_GET(GT_L3_EXC_MASK,
+					      xe_mmio_read32(gt, XEHP_FUSE4.reg));
+
+		/*
+		 * Group selects mslice, instance selects bank within mslice.
+		 * Bank 0 is always valid _except_ when the bank mask is 010b.
+		 */
+		gt->steering[L3BANK].group_target = __ffs(mslice_mask);
+		gt->steering[L3BANK].instance_target =
+			bank_mask & BIT(0) ? 0 : 2;
+	} else {
+		u32 fuse = REG_FIELD_GET(GEN10_L3BANK_MASK,
+					 ~xe_mmio_read32(gt, GEN10_MIRROR_FUSE3.reg));
+
+		gt->steering[L3BANK].group_target = 0;	/* unused */
+		gt->steering[L3BANK].instance_target = __ffs(fuse);
+	}
+}
+
+static void init_steering_mslice(struct xe_gt *gt)
+{
+	u32 mask = REG_FIELD_GET(GEN12_MEML3_EN_MASK,
+				 xe_mmio_read32(gt, GEN10_MIRROR_FUSE3.reg));
+
+	/*
+	 * mslice registers are valid (not terminated) if either the meml3
+	 * associated with the mslice is present, or at least one DSS associated
+	 * with the mslice is present.  There will always be at least one meml3
+	 * so we can just use that to find a non-terminated mslice and ignore
+	 * the DSS fusing.
+	 */
+	gt->steering[MSLICE].group_target = __ffs(mask);
+	gt->steering[MSLICE].instance_target = 0;	/* unused */
+
+	/*
+	 * LNCF termination is also based on mslice presence, so we'll set
+	 * it up here.  Either LNCF within a non-terminated mslice will work,
+	 * so we just always pick LNCF 0 here.
+	 */
+	gt->steering[LNCF].group_target = __ffs(mask) << 1;
+	gt->steering[LNCF].instance_target = 0;		/* unused */
+}
+
+static void init_steering_dss(struct xe_gt *gt)
+{
+	unsigned int dss = min(xe_dss_mask_group_ffs(gt->fuse_topo.g_dss_mask, 0, 0),
+			       xe_dss_mask_group_ffs(gt->fuse_topo.c_dss_mask, 0, 0));
+	unsigned int dss_per_grp = gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
+
+	gt->steering[DSS].group_target = dss / dss_per_grp;
+	gt->steering[DSS].instance_target = dss % dss_per_grp;
+}
+
+static void init_steering_oaddrm(struct xe_gt *gt)
+{
+	/*
+	 * First instance is only terminated if the entire first media slice
+	 * is absent (i.e., no VCS0 or VECS0).
+	 */
+	if (gt->info.engine_mask & (XE_HW_ENGINE_VCS0 | XE_HW_ENGINE_VECS0))
+		gt->steering[OADDRM].group_target = 0;
+	else
+		gt->steering[OADDRM].group_target = 1;
+
+	gt->steering[DSS].instance_target = 0;		/* unused */
+}
+
+static void init_steering_inst0(struct xe_gt *gt)
+{
+	gt->steering[DSS].group_target = 0;		/* unused */
+	gt->steering[DSS].instance_target = 0;		/* unused */
+}
+
+static const struct {
+	const char *name;
+	void (*init)(struct xe_gt *);
+} xe_steering_types[] = {
+	{ "L3BANK",	init_steering_l3bank },
+	{ "MSLICE",	init_steering_mslice },
+	{ "LNCF",	NULL },		/* initialized by mslice init */
+	{ "DSS",	init_steering_dss },
+	{ "OADDRM",	init_steering_oaddrm },
+	{ "INSTANCE 0",	init_steering_inst0 },
+};
+
+void xe_gt_mcr_init(struct xe_gt *gt)
+{
+	struct xe_device *xe = gt_to_xe(gt);
+
+	BUILD_BUG_ON(ARRAY_SIZE(xe_steering_types) != NUM_STEERING_TYPES);
+
+	spin_lock_init(&gt->mcr_lock);
+
+	if (gt->info.type == XE_GT_TYPE_MEDIA) {
+		drm_WARN_ON(&xe->drm, MEDIA_VER(xe) < 13);
+
+		gt->steering[OADDRM].ranges = xelpmp_oaddrm_steering_table;
+	} else if (GRAPHICS_VERx100(xe) >= 1270) {
+		gt->steering[INSTANCE0].ranges = xelpg_instance0_steering_table;
+		gt->steering[L3BANK].ranges = xelpg_l3bank_steering_table;
+		gt->steering[DSS].ranges = xelpg_dss_steering_table;
+	} else if (xe->info.platform == XE_PVC) {
+		gt->steering[INSTANCE0].ranges = xehpc_instance0_steering_table;
+		gt->steering[DSS].ranges = xehpc_dss_steering_table;
+	} else if (xe->info.platform == XE_DG2) {
+		gt->steering[MSLICE].ranges = xehp_mslice_steering_table;
+		gt->steering[LNCF].ranges = xehp_lncf_steering_table;
+		gt->steering[DSS].ranges = xehp_dss_steering_table;
+	} else {
+		gt->steering[L3BANK].ranges = xelp_l3bank_steering_table;
+		gt->steering[DSS].ranges = xelp_dss_steering_table;
+	}
+
+	/* Select non-terminated steering target for each type */
+	for (int i = 0; i < NUM_STEERING_TYPES; i++)
+		if (gt->steering[i].ranges && xe_steering_types[i].init)
+			xe_steering_types[i].init(gt);
+}
+
+/*
+ * xe_gt_mcr_get_nonterminated_steering - find group/instance values that
+ *    will steer a register to a non-terminated instance
+ * @gt: GT structure
+ * @reg: register for which the steering is required
+ * @group: return variable for group steering
+ * @instance: return variable for instance steering
+ *
+ * This function returns a group/instance 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.
+ *
+ * Returns true if the caller should steer to the @group/@instance values
+ * returned.  Returns false if the caller need not perform any steering (i.e.,
+ * the DG2 GAM range special case).
+ */
+static bool xe_gt_mcr_get_nonterminated_steering(struct xe_gt *gt,
+						 i915_mcr_reg_t reg,
+						 u8 *group, u8 *instance)
+{
+	for (int type = 0; type < NUM_STEERING_TYPES; type++) {
+		if (!gt->steering[type].ranges)
+			continue;
+
+		for (int i = 0; gt->steering[type].ranges[i].end > 0; i++) {
+			if (xe_mmio_in_range(&gt->steering[type].ranges[i], reg.reg)) {
+				*group = gt->steering[type].group_target;
+				*instance = gt->steering[type].instance_target;
+				return true;
+			}
+		}
+	}
+
+	/*
+	 * All MCR registers should usually be part of one of the steering
+	 * ranges we're tracking.  However there's one special case:  DG2
+	 * GAM registers are technically multicast registers, but are special
+	 * in a number of ways:
+	 *  - they have their own dedicated steering control register (they
+	 *    don't share 0xFDC with other MCR classes)
+	 *  - all reads should be directed to instance 1 (unicast reads against
+	 *    other instances are not allowed), and instance 1 is already the
+	 *    the hardware's default steering target, which we never change
+	 *
+	 * Ultimately this means that we can just treat them as if they were
+	 * unicast registers and all operations will work properly.
+	 */
+	for (int i = 0; dg2_gam_ranges[i].end > 0; i++)
+		if (xe_mmio_in_range(&dg2_gam_ranges[i], reg.reg))
+			return false;
+
+	/*
+	 * Not found in a steering table and not a DG2 GAM register?  We'll
+	 * just steer to 0/0 as a guess and raise a warning.
+	 */
+	drm_WARN(&gt_to_xe(gt)->drm, true,
+		 "Did not find MCR register %#x in any MCR steering table\n",
+		 reg.reg);
+	*group = 0;
+	*instance = 0;
+
+	return true;
+}
+
+#define STEER_SEMAPHORE		0xFD0
+
+/*
+ * Obtain exclusive access to MCR steering.  On MTL and beyond we also need
+ * to synchronize with external clients (e.g., firmware), so a semaphore
+ * register will also need to be taken.
+ */
+static void mcr_lock(struct xe_gt *gt)
+{
+	struct xe_device *xe = gt_to_xe(gt);
+	int ret;
+
+	spin_lock(&gt->mcr_lock);
+
+	/*
+	 * Starting with MTL we also need to grab a semaphore register
+	 * to synchronize with external agents (e.g., firmware) that now
+	 * shares the same steering control register.
+	 */
+	if (GRAPHICS_VERx100(xe) >= 1270)
+		ret = wait_for_us(xe_mmio_read32(gt, STEER_SEMAPHORE) == 0x1, 10);
+
+	drm_WARN_ON_ONCE(&xe->drm, ret == -ETIMEDOUT);
+}
+
+static void mcr_unlock(struct xe_gt *gt) {
+	/* Release hardware semaphore */
+	if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 1270)
+		xe_mmio_write32(gt, STEER_SEMAPHORE, 0x1);
+
+	spin_unlock(&gt->mcr_lock);
+}
+
+/*
+ * Access a register with specific MCR steering
+ *
+ * Caller needs to make sure the relevant forcewake wells are up.
+ */
+static u32 rw_with_mcr_steering(struct xe_gt *gt, i915_mcr_reg_t reg, u8 rw_flag,
+				int group, int instance, u32 value)
+{
+	u32 steer_reg, steer_val, val = 0;
+
+	lockdep_assert_held(&gt->mcr_lock);
+
+	if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 1270) {
+		steer_reg = MTL_MCR_SELECTOR.reg;
+		steer_val = REG_FIELD_PREP(MTL_MCR_GROUPID, group) |
+			REG_FIELD_PREP(MTL_MCR_INSTANCEID, instance);
+	} else {
+		steer_reg = GEN8_MCR_SELECTOR.reg;
+		steer_val = REG_FIELD_PREP(GEN11_MCR_SLICE_MASK, group) |
+			REG_FIELD_PREP(GEN11_MCR_SUBSLICE_MASK, instance);
+	}
+
+	/*
+	 * Always leave the hardware in multicast mode when doing reads
+	 * (see comment about Wa_22013088509 below) and only change it
+	 * to unicast mode when doing writes of a specific instance.
+	 *
+	 * No need to save old steering reg value.
+	 */
+	if (rw_flag == MCR_OP_READ)
+		steer_val |= GEN11_MCR_MULTICAST;
+
+	xe_mmio_write32(gt, steer_reg, steer_val);
+
+	if (rw_flag == MCR_OP_READ)
+		val = xe_mmio_read32(gt, reg.reg);
+	else
+		xe_mmio_write32(gt, reg.reg, value);
+
+	/*
+	 * If we turned off the multicast bit (during a write) we're required
+	 * to turn it back on before finishing.  The group and instance values
+	 * don't matter since they'll be re-programmed on the next MCR
+	 * operation.
+	 */
+	if (rw_flag == MCR_OP_WRITE)
+		xe_mmio_write32(gt, steer_reg, GEN11_MCR_MULTICAST);
+
+	return val;
+}
+
+/**
+ * xe_gt_mcr_unicast_read_any - reads a non-terminated instance of an MCR register
+ * @gt: GT structure
+ * @reg: register to read
+ *
+ * Reads a GT MCR register.  The read will be steered to a non-terminated
+ * instance (i.e., one that isn't fused off or powered down by power gating).
+ * This function assumes the caller is already holding any necessary forcewake
+ * domains.
+ *
+ * Returns the value from a non-terminated instance of @reg.
+ */
+u32 xe_gt_mcr_unicast_read_any(struct xe_gt *gt, i915_mcr_reg_t reg)
+{
+	u8 group, instance;
+	u32 val;
+	bool steer;
+
+	steer = xe_gt_mcr_get_nonterminated_steering(gt, reg, &group, &instance);
+
+	if (steer) {
+		mcr_lock(gt);
+		val = rw_with_mcr_steering(gt, reg, MCR_OP_READ,
+					   group, instance, 0);
+		mcr_unlock(gt);
+	} else {
+		/* DG2 GAM special case rules; treat as if unicast */
+		val = xe_mmio_read32(gt, reg.reg);
+	}
+
+	return val;
+}
+
+/**
+ * xe_gt_mcr_unicast_read - read a specific instance of an MCR register
+ * @gt: GT structure
+ * @reg: the MCR register to read
+ * @group: the MCR group
+ * @instance: the MCR instance
+ *
+ * Returns the value read from an MCR register after steering toward a specific
+ * group/instance.
+ */
+u32 xe_gt_mcr_unicast_read(struct xe_gt *gt,
+			   i915_mcr_reg_t reg,
+			   int group, int instance)
+{
+	u32 val;
+
+	mcr_lock(gt);
+	val = rw_with_mcr_steering(gt, reg, MCR_OP_READ, group, instance, 0);
+	mcr_unlock(gt);
+
+	return val;
+}
+
+/**
+ * xe_gt_mcr_unicast_write - write a specific instance of an MCR register
+ * @gt: GT structure
+ * @reg: the MCR register to write
+ * @value: value to write
+ * @group: the MCR group
+ * @instance: the MCR instance
+ *
+ * Write an MCR register in unicast mode after steering toward a specific
+ * group/instance.
+ */
+void xe_gt_mcr_unicast_write(struct xe_gt *gt, i915_mcr_reg_t reg, u32 value,
+			     int group, int instance)
+{
+	mcr_lock(gt);
+	rw_with_mcr_steering(gt, reg, MCR_OP_WRITE, group, instance, value);
+	mcr_unlock(gt);
+}
+
+/**
+ * xe_gt_mcr_multicast_write - write a value to all instances of an MCR register
+ * @gt: GT structure
+ * @reg: the MCR register to write
+ * @value: value to write
+ *
+ * Write an MCR register in multicast mode to update all instances.
+ */
+void xe_gt_mcr_multicast_write(struct xe_gt *gt, i915_mcr_reg_t reg, u32 value)
+{
+	/*
+	 * Synchronize with any unicast operations.  Once we have exclusive
+	 * access, the MULTICAST bit should already be set, so there's no need
+	 * to touch the steering register.
+	 */
+	mcr_lock(gt);
+	xe_mmio_write32(gt, reg.reg, value);
+	mcr_unlock(gt);
+}
+
+void xe_gt_mcr_steering_dump(struct xe_gt *gt, struct drm_printer *p)
+{
+	for (int i = 0; i < NUM_STEERING_TYPES; i++) {
+		if (gt->steering[i].ranges) {
+			drm_printf(p, "%s steering: group=%#x, instance=%#x\n",
+				   xe_steering_types[i].name,
+				   gt->steering[i].group_target,
+				   gt->steering[i].instance_target);
+			for (int j = 0; gt->steering[i].ranges[j].end; j++)
+				drm_printf(p, "\t0x%06x - 0x%06x\n",
+					   gt->steering[i].ranges[j].start,
+					   gt->steering[i].ranges[j].end);
+		}
+	}
+}