intel_gt.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2019 Intel Corporation
 */

#include "debugfs_gt.h"

#include "gem/i915_gem_lmem.h"
#include "i915_drv.h"
#include "intel_context.h"
#include "intel_gt.h"
#include "intel_gt_buffer_pool.h"
#include "intel_gt_clock_utils.h"
#include "intel_gt_pm.h"
#include "intel_gt_requests.h"
#include "intel_migrate.h"
#include "intel_mocs.h"
#include "intel_rc6.h"
#include "intel_renderstate.h"
#include "intel_rps.h"
#include "intel_uncore.h"
#include "intel_pm.h"
#include "shmem_utils.h"

void intel_gt_init_early(struct intel_gt *gt, struct drm_i915_private *i915)
{
	gt->i915 = i915;
	gt->uncore = &i915->uncore;

	spin_lock_init(&gt->irq_lock);

	INIT_LIST_HEAD(&gt->closed_vma);
	spin_lock_init(&gt->closed_lock);

	init_llist_head(&gt->watchdog.list);
	INIT_WORK(&gt->watchdog.work, intel_gt_watchdog_work);

	intel_gt_init_buffer_pool(gt);
	intel_gt_init_reset(gt);
	intel_gt_init_requests(gt);
	intel_gt_init_timelines(gt);
	intel_gt_pm_init_early(gt);

	intel_uc_init_early(&gt->uc);
	intel_rps_init_early(&gt->rps);
}

int intel_gt_probe_lmem(struct intel_gt *gt)
{
	struct drm_i915_private *i915 = gt->i915;
	struct intel_memory_region *mem;
	int id;
	int err;

	mem = intel_gt_setup_lmem(gt);
	if (mem == ERR_PTR(-ENODEV))
		mem = intel_gt_setup_fake_lmem(gt);
	if (IS_ERR(mem)) {
		err = PTR_ERR(mem);
		if (err == -ENODEV)
			return 0;

		drm_err(&i915->drm,
			"Failed to setup region(%d) type=%d\n",
			err, INTEL_MEMORY_LOCAL);
		return err;
	}

	id = INTEL_REGION_LMEM;

	mem->id = id;

	intel_memory_region_set_name(mem, "local%u", mem->instance);

	GEM_BUG_ON(!HAS_REGION(i915, id));
	GEM_BUG_ON(i915->mm.regions[id]);
	i915->mm.regions[id] = mem;

	return 0;
}

void intel_gt_init_hw_early(struct intel_gt *gt, struct i915_ggtt *ggtt)
{
	gt->ggtt = ggtt;
}

static const struct intel_mmio_range icl_l3bank_steering_table[] = {
	{ 0x00B100, 0x00B3FF },
	{},
};

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 (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);
	}

	return intel_engines_init_mmio(gt);
}

static void init_unused_ring(struct intel_gt *gt, u32 base)
{
	struct intel_uncore *uncore = gt->uncore;

	intel_uncore_write(uncore, RING_CTL(base), 0);
	intel_uncore_write(uncore, RING_HEAD(base), 0);
	intel_uncore_write(uncore, RING_TAIL(base), 0);
	intel_uncore_write(uncore, RING_START(base), 0);
}

static void init_unused_rings(struct intel_gt *gt)
{
	struct drm_i915_private *i915 = gt->i915;

	if (IS_I830(i915)) {
		init_unused_ring(gt, PRB1_BASE);
		init_unused_ring(gt, SRB0_BASE);
		init_unused_ring(gt, SRB1_BASE);
		init_unused_ring(gt, SRB2_BASE);
		init_unused_ring(gt, SRB3_BASE);
	} else if (GRAPHICS_VER(i915) == 2) {
		init_unused_ring(gt, SRB0_BASE);
		init_unused_ring(gt, SRB1_BASE);
	} else if (GRAPHICS_VER(i915) == 3) {
		init_unused_ring(gt, PRB1_BASE);
		init_unused_ring(gt, PRB2_BASE);
	}
}

int intel_gt_init_hw(struct intel_gt *gt)
{
	struct drm_i915_private *i915 = gt->i915;
	struct intel_uncore *uncore = gt->uncore;
	int ret;

	gt->last_init_time = ktime_get();

	/* Double layer security blanket, see i915_gem_init() */
	intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL);

	if (HAS_EDRAM(i915) && GRAPHICS_VER(i915) < 9)
		intel_uncore_rmw(uncore, HSW_IDICR, 0, IDIHASHMSK(0xf));

	if (IS_HASWELL(i915))
		intel_uncore_write(uncore,
				   MI_PREDICATE_RESULT_2,
				   IS_HSW_GT3(i915) ?
				   LOWER_SLICE_ENABLED : LOWER_SLICE_DISABLED);

	/* Apply the GT workarounds... */
	intel_gt_apply_workarounds(gt);
	/* ...and determine whether they are sticking. */
	intel_gt_verify_workarounds(gt, "init");

	intel_gt_init_swizzling(gt);

	/*
	 * At least 830 can leave some of the unused rings
	 * "active" (ie. head != tail) after resume which
	 * will prevent c3 entry. Makes sure all unused rings
	 * are totally idle.
	 */
	init_unused_rings(gt);

	ret = i915_ppgtt_init_hw(gt);
	if (ret) {
		DRM_ERROR("Enabling PPGTT failed (%d)\n", ret);
		goto out;
	}

	/* We can't enable contexts until all firmware is loaded */
	ret = intel_uc_init_hw(&gt->uc);
	if (ret) {
		i915_probe_error(i915, "Enabling uc failed (%d)\n", ret);
		goto out;
	}

	intel_mocs_init(gt);

out:
	intel_uncore_forcewake_put(uncore, FORCEWAKE_ALL);
	return ret;
}

static void rmw_set(struct intel_uncore *uncore, i915_reg_t reg, u32 set)
{
	intel_uncore_rmw(uncore, reg, 0, set);
}

static void rmw_clear(struct intel_uncore *uncore, i915_reg_t reg, u32 clr)
{
	intel_uncore_rmw(uncore, reg, clr, 0);
}

static void clear_register(struct intel_uncore *uncore, i915_reg_t reg)
{
	intel_uncore_rmw(uncore, reg, 0, 0);
}

static void gen6_clear_engine_error_register(struct intel_engine_cs *engine)
{
	GEN6_RING_FAULT_REG_RMW(engine, RING_FAULT_VALID, 0);
	GEN6_RING_FAULT_REG_POSTING_READ(engine);
}

void
intel_gt_clear_error_registers(struct intel_gt *gt,
			       intel_engine_mask_t engine_mask)
{
	struct drm_i915_private *i915 = gt->i915;
	struct intel_uncore *uncore = gt->uncore;
	u32 eir;

	if (GRAPHICS_VER(i915) != 2)
		clear_register(uncore, PGTBL_ER);

	if (GRAPHICS_VER(i915) < 4)
		clear_register(uncore, IPEIR(RENDER_RING_BASE));
	else
		clear_register(uncore, IPEIR_I965);

	clear_register(uncore, EIR);
	eir = intel_uncore_read(uncore, EIR);
	if (eir) {
		/*
		 * some errors might have become stuck,
		 * mask them.
		 */
		DRM_DEBUG_DRIVER("EIR stuck: 0x%08x, masking\n", eir);
		rmw_set(uncore, EMR, eir);
		intel_uncore_write(uncore, GEN2_IIR,
				   I915_MASTER_ERROR_INTERRUPT);
	}

	if (GRAPHICS_VER(i915) >= 12) {
		rmw_clear(uncore, GEN12_RING_FAULT_REG, RING_FAULT_VALID);
		intel_uncore_posting_read(uncore, GEN12_RING_FAULT_REG);
	} else if (GRAPHICS_VER(i915) >= 8) {
		rmw_clear(uncore, GEN8_RING_FAULT_REG, RING_FAULT_VALID);
		intel_uncore_posting_read(uncore, GEN8_RING_FAULT_REG);
	} else if (GRAPHICS_VER(i915) >= 6) {
		struct intel_engine_cs *engine;
		enum intel_engine_id id;

		for_each_engine_masked(engine, gt, engine_mask, id)
			gen6_clear_engine_error_register(engine);
	}
}

static void gen6_check_faults(struct intel_gt *gt)
{
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	u32 fault;

	for_each_engine(engine, gt, id) {
		fault = GEN6_RING_FAULT_REG_READ(engine);
		if (fault & RING_FAULT_VALID) {
			drm_dbg(&engine->i915->drm, "Unexpected fault\n"
				"\tAddr: 0x%08lx\n"
				"\tAddress space: %s\n"
				"\tSource ID: %d\n"
				"\tType: %d\n",
				fault & PAGE_MASK,
				fault & RING_FAULT_GTTSEL_MASK ?
				"GGTT" : "PPGTT",
				RING_FAULT_SRCID(fault),
				RING_FAULT_FAULT_TYPE(fault));
		}
	}
}

static void gen8_check_faults(struct intel_gt *gt)
{
	struct intel_uncore *uncore = gt->uncore;
	i915_reg_t fault_reg, fault_data0_reg, fault_data1_reg;
	u32 fault;

	if (GRAPHICS_VER(gt->i915) >= 12) {
		fault_reg = GEN12_RING_FAULT_REG;
		fault_data0_reg = GEN12_FAULT_TLB_DATA0;
		fault_data1_reg = GEN12_FAULT_TLB_DATA1;
	} else {
		fault_reg = GEN8_RING_FAULT_REG;
		fault_data0_reg = GEN8_FAULT_TLB_DATA0;
		fault_data1_reg = GEN8_FAULT_TLB_DATA1;
	}

	fault = intel_uncore_read(uncore, fault_reg);
	if (fault & RING_FAULT_VALID) {
		u32 fault_data0, fault_data1;
		u64 fault_addr;

		fault_data0 = intel_uncore_read(uncore, fault_data0_reg);
		fault_data1 = intel_uncore_read(uncore, fault_data1_reg);

		fault_addr = ((u64)(fault_data1 & FAULT_VA_HIGH_BITS) << 44) |
			     ((u64)fault_data0 << 12);

		drm_dbg(&uncore->i915->drm, "Unexpected fault\n"
			"\tAddr: 0x%08x_%08x\n"
			"\tAddress space: %s\n"
			"\tEngine ID: %d\n"
			"\tSource ID: %d\n"
			"\tType: %d\n",
			upper_32_bits(fault_addr), lower_32_bits(fault_addr),
			fault_data1 & FAULT_GTT_SEL ? "GGTT" : "PPGTT",
			GEN8_RING_FAULT_ENGINE_ID(fault),
			RING_FAULT_SRCID(fault),
			RING_FAULT_FAULT_TYPE(fault));
	}
}

void intel_gt_check_and_clear_faults(struct intel_gt *gt)
{
	struct drm_i915_private *i915 = gt->i915;

	/* From GEN8 onwards we only have one 'All Engine Fault Register' */
	if (GRAPHICS_VER(i915) >= 8)
		gen8_check_faults(gt);
	else if (GRAPHICS_VER(i915) >= 6)
		gen6_check_faults(gt);
	else
		return;

	intel_gt_clear_error_registers(gt, ALL_ENGINES);
}

void intel_gt_flush_ggtt_writes(struct intel_gt *gt)
{
	struct intel_uncore *uncore = gt->uncore;
	intel_wakeref_t wakeref;

	/*
	 * No actual flushing is required for the GTT write domain for reads
	 * from the GTT domain. Writes to it "immediately" go to main memory
	 * as far as we know, so there's no chipset flush. It also doesn't
	 * land in the GPU render cache.
	 *
	 * However, we do have to enforce the order so that all writes through
	 * the GTT land before any writes to the device, such as updates to
	 * the GATT itself.
	 *
	 * We also have to wait a bit for the writes to land from the GTT.
	 * An uncached read (i.e. mmio) seems to be ideal for the round-trip
	 * timing. This issue has only been observed when switching quickly
	 * between GTT writes and CPU reads from inside the kernel on recent hw,
	 * and it appears to only affect discrete GTT blocks (i.e. on LLC
	 * system agents we cannot reproduce this behaviour, until Cannonlake
	 * that was!).
	 */

	wmb();

	if (INTEL_INFO(gt->i915)->has_coherent_ggtt)
		return;

	intel_gt_chipset_flush(gt);

	with_intel_runtime_pm_if_in_use(uncore->rpm, wakeref) {
		unsigned long flags;

		spin_lock_irqsave(&uncore->lock, flags);
		intel_uncore_posting_read_fw(uncore,
					     RING_HEAD(RENDER_RING_BASE));
		spin_unlock_irqrestore(&uncore->lock, flags);
	}
}

void intel_gt_chipset_flush(struct intel_gt *gt)
{
	wmb();
	if (GRAPHICS_VER(gt->i915) < 6)
		intel_gtt_chipset_flush();
}

void intel_gt_driver_register(struct intel_gt *gt)
{
	intel_rps_driver_register(&gt->rps);

	debugfs_gt_register(gt);
}

static int intel_gt_init_scratch(struct intel_gt *gt, unsigned int size)
{
	struct drm_i915_private *i915 = gt->i915;
	struct drm_i915_gem_object *obj;
	struct i915_vma *vma;
	int ret;

	obj = i915_gem_object_create_lmem(i915, size, I915_BO_ALLOC_VOLATILE);
	if (IS_ERR(obj))
		obj = i915_gem_object_create_stolen(i915, size);
	if (IS_ERR(obj))
		obj = i915_gem_object_create_internal(i915, size);
	if (IS_ERR(obj)) {
		drm_err(&i915->drm, "Failed to allocate scratch page\n");
		return PTR_ERR(obj);
	}

	vma = i915_vma_instance(obj, &gt->ggtt->vm, NULL);
	if (IS_ERR(vma)) {
		ret = PTR_ERR(vma);
		goto err_unref;
	}

	ret = i915_ggtt_pin(vma, NULL, 0, PIN_HIGH);
	if (ret)
		goto err_unref;

	gt->scratch = i915_vma_make_unshrinkable(vma);

	return 0;

err_unref:
	i915_gem_object_put(obj);
	return ret;
}

static void intel_gt_fini_scratch(struct intel_gt *gt)
{
	i915_vma_unpin_and_release(&gt->scratch, 0);
}

static struct i915_address_space *kernel_vm(struct intel_gt *gt)
{
	if (INTEL_PPGTT(gt->i915) > INTEL_PPGTT_ALIASING)
		return &i915_ppgtt_create(gt)->vm;
	else
		return i915_vm_get(&gt->ggtt->vm);
}

static int __engines_record_defaults(struct intel_gt *gt)
{
	struct i915_request *requests[I915_NUM_ENGINES] = {};
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	int err = 0;

	/*
	 * As we reset the gpu during very early sanitisation, the current
	 * register state on the GPU should reflect its defaults values.
	 * We load a context onto the hw (with restore-inhibit), then switch
	 * over to a second context to save that default register state. We
	 * can then prime every new context with that state so they all start
	 * from the same default HW values.
	 */

	for_each_engine(engine, gt, id) {
		struct intel_renderstate so;
		struct intel_context *ce;
		struct i915_request *rq;

		/* We must be able to switch to something! */
		GEM_BUG_ON(!engine->kernel_context);

		ce = intel_context_create(engine);
		if (IS_ERR(ce)) {
			err = PTR_ERR(ce);
			goto out;
		}

		err = intel_renderstate_init(&so, ce);
		if (err)
			goto err;

		rq = i915_request_create(ce);
		if (IS_ERR(rq)) {
			err = PTR_ERR(rq);
			goto err_fini;
		}

		err = intel_engine_emit_ctx_wa(rq);
		if (err)
			goto err_rq;

		err = intel_renderstate_emit(&so, rq);
		if (err)
			goto err_rq;

err_rq:
		requests[id] = i915_request_get(rq);
		i915_request_add(rq);
err_fini:
		intel_renderstate_fini(&so, ce);
err:
		if (err) {
			intel_context_put(ce);
			goto out;
		}
	}

	/* Flush the default context image to memory, and enable powersaving. */
	if (intel_gt_wait_for_idle(gt, I915_GEM_IDLE_TIMEOUT) == -ETIME) {
		err = -EIO;
		goto out;
	}

	for (id = 0; id < ARRAY_SIZE(requests); id++) {
		struct i915_request *rq;
		struct file *state;

		rq = requests[id];
		if (!rq)
			continue;

		if (rq->fence.error) {
			err = -EIO;
			goto out;
		}

		GEM_BUG_ON(!test_bit(CONTEXT_ALLOC_BIT, &rq->context->flags));
		if (!rq->context->state)
			continue;

		/* Keep a copy of the state's backing pages; free the obj */
		state = shmem_create_from_object(rq->context->state->obj);
		if (IS_ERR(state)) {
			err = PTR_ERR(state);
			goto out;
		}
		rq->engine->default_state = state;
	}

out:
	/*
	 * If we have to abandon now, we expect the engines to be idle
	 * and ready to be torn-down. The quickest way we can accomplish
	 * this is by declaring ourselves wedged.
	 */
	if (err)
		intel_gt_set_wedged(gt);

	for (id = 0; id < ARRAY_SIZE(requests); id++) {
		struct intel_context *ce;
		struct i915_request *rq;

		rq = requests[id];
		if (!rq)
			continue;

		ce = rq->context;
		i915_request_put(rq);
		intel_context_put(ce);
	}
	return err;
}

static int __engines_verify_workarounds(struct intel_gt *gt)
{
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	int err = 0;

	if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
		return 0;

	for_each_engine(engine, gt, id) {
		if (intel_engine_verify_workarounds(engine, "load"))
			err = -EIO;
	}

	/* Flush and restore the kernel context for safety */
	if (intel_gt_wait_for_idle(gt, I915_GEM_IDLE_TIMEOUT) == -ETIME)
		err = -EIO;

	return err;
}

static void __intel_gt_disable(struct intel_gt *gt)
{
	intel_gt_set_wedged_on_fini(gt);

	intel_gt_suspend_prepare(gt);
	intel_gt_suspend_late(gt);

	GEM_BUG_ON(intel_gt_pm_is_awake(gt));
}

int intel_gt_wait_for_idle(struct intel_gt *gt, long timeout)
{
	long remaining_timeout;

	/* If the device is asleep, we have no requests outstanding */
	if (!intel_gt_pm_is_awake(gt))
		return 0;

	while ((timeout = intel_gt_retire_requests_timeout(gt, timeout,
							   &remaining_timeout)) > 0) {
		cond_resched();
		if (signal_pending(current))
			return -EINTR;
	}

	return timeout ? timeout : intel_uc_wait_for_idle(&gt->uc,
							  remaining_timeout);
}

int intel_gt_init(struct intel_gt *gt)
{
	int err;

	err = i915_inject_probe_error(gt->i915, -ENODEV);
	if (err)
		return err;

	/*
	 * This is just a security blanket to placate dragons.
	 * On some systems, we very sporadically observe that the first TLBs
	 * used by the CS may be stale, despite us poking the TLB reset. If
	 * we hold the forcewake during initialisation these problems
	 * just magically go away.
	 */
	intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_ALL);

	err = intel_gt_init_scratch(gt,
				    GRAPHICS_VER(gt->i915) == 2 ? SZ_256K : SZ_4K);
	if (err)
		goto out_fw;

	intel_gt_pm_init(gt);

	gt->vm = kernel_vm(gt);
	if (!gt->vm) {
		err = -ENOMEM;
		goto err_pm;
	}

	err = intel_engines_init(gt);
	if (err)
		goto err_engines;

	err = intel_uc_init(&gt->uc);
	if (err)
		goto err_engines;

	err = intel_gt_resume(gt);
	if (err)
		goto err_uc_init;

	err = __engines_record_defaults(gt);
	if (err)
		goto err_gt;

	err = __engines_verify_workarounds(gt);
	if (err)
		goto err_gt;

	intel_uc_init_late(&gt->uc);

	err = i915_inject_probe_error(gt->i915, -EIO);
	if (err)
		goto err_gt;

	intel_migrate_init(&gt->migrate, gt);

	goto out_fw;
err_gt:
	__intel_gt_disable(gt);
	intel_uc_fini_hw(&gt->uc);
err_uc_init:
	intel_uc_fini(&gt->uc);
err_engines:
	intel_engines_release(gt);
	i915_vm_put(fetch_and_zero(&gt->vm));
err_pm:
	intel_gt_pm_fini(gt);
	intel_gt_fini_scratch(gt);
out_fw:
	if (err)
		intel_gt_set_wedged_on_init(gt);
	intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_ALL);
	return err;
}

void intel_gt_driver_remove(struct intel_gt *gt)
{
	__intel_gt_disable(gt);

	intel_migrate_fini(&gt->migrate);
	intel_uc_driver_remove(&gt->uc);

	intel_engines_release(gt);
}

void intel_gt_driver_unregister(struct intel_gt *gt)
{
	intel_wakeref_t wakeref;

	intel_rps_driver_unregister(&gt->rps);

	/*
	 * Upon unregistering the device to prevent any new users, cancel
	 * all in-flight requests so that we can quickly unbind the active
	 * resources.
	 */
	intel_gt_set_wedged(gt);

	/* Scrub all HW state upon release */
	with_intel_runtime_pm(gt->uncore->rpm, wakeref)
		__intel_gt_reset(gt, ALL_ENGINES);
}

void intel_gt_driver_release(struct intel_gt *gt)
{
	struct i915_address_space *vm;

	vm = fetch_and_zero(&gt->vm);
	if (vm) /* FIXME being called twice on error paths :( */
		i915_vm_put(vm);

	intel_gt_pm_fini(gt);
	intel_gt_fini_scratch(gt);
	intel_gt_fini_buffer_pool(gt);
}

void intel_gt_driver_late_release(struct intel_gt *gt)
{
	/* We need to wait for inflight RCU frees to release their grip */
	rcu_barrier();

	intel_uc_driver_late_release(&gt->uc);
	intel_gt_fini_requests(gt);
	intel_gt_fini_reset(gt);
	intel_gt_fini_timelines(gt);
	intel_engines_free(gt);
}

/**
 * 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);
}

void intel_gt_info_print(const struct intel_gt_info *info,
			 struct drm_printer *p)
{
	drm_printf(p, "available engines: %x\n", info->engine_mask);

	intel_sseu_dump(&info->sseu, p);
}