// SPDX-License-Identifier: MIT
/*
 * Copyright © 2020 Intel Corporation
 */

#include <linux/sort.h>

#include "intel_engine_pm.h"
#include "intel_gt_pm.h"
#include "intel_rc6.h"
#include "selftest_rps.h"
#include "selftests/igt_flush_test.h"
#include "selftests/igt_spinner.h"
#include "selftests/librapl.h"

static void dummy_rps_work(struct work_struct *wrk)
{
}

static void sleep_for_ei(struct intel_rps *rps, int timeout_us)
{
	/* Flush any previous EI */
	usleep_range(timeout_us, 2 * timeout_us);

	/* Reset the interrupt status */
	rps_disable_interrupts(rps);
	GEM_BUG_ON(rps->pm_iir);
	rps_enable_interrupts(rps);

	/* And then wait for the timeout, for real this time */
	usleep_range(2 * timeout_us, 3 * timeout_us);
}

static int __rps_up_interrupt(struct intel_rps *rps,
			      struct intel_engine_cs *engine,
			      struct igt_spinner *spin)
{
	struct intel_uncore *uncore = engine->uncore;
	struct i915_request *rq;
	u32 timeout;

	if (!intel_engine_can_store_dword(engine))
		return 0;

	mutex_lock(&rps->lock);
	GEM_BUG_ON(!rps->active);
	intel_rps_set(rps, rps->min_freq);
	mutex_unlock(&rps->lock);

	rq = igt_spinner_create_request(spin, engine->kernel_context, MI_NOOP);
	if (IS_ERR(rq))
		return PTR_ERR(rq);

	i915_request_get(rq);
	i915_request_add(rq);

	if (!igt_wait_for_spinner(spin, rq)) {
		pr_err("%s: RPS spinner did not start\n",
		       engine->name);
		i915_request_put(rq);
		intel_gt_set_wedged(engine->gt);
		return -EIO;
	}

	if (!rps->active) {
		pr_err("%s: RPS not enabled on starting spinner\n",
		       engine->name);
		igt_spinner_end(spin);
		i915_request_put(rq);
		return -EINVAL;
	}

	if (!(rps->pm_events & GEN6_PM_RP_UP_THRESHOLD)) {
		pr_err("%s: RPS did not register UP interrupt\n",
		       engine->name);
		i915_request_put(rq);
		return -EINVAL;
	}

	if (rps->last_freq != rps->min_freq) {
		pr_err("%s: RPS did not program min frequency\n",
		       engine->name);
		i915_request_put(rq);
		return -EINVAL;
	}

	timeout = intel_uncore_read(uncore, GEN6_RP_UP_EI);
	timeout = GT_PM_INTERVAL_TO_US(engine->i915, timeout);

	sleep_for_ei(rps, timeout);
	GEM_BUG_ON(i915_request_completed(rq));

	igt_spinner_end(spin);
	i915_request_put(rq);

	if (rps->cur_freq != rps->min_freq) {
		pr_err("%s: Frequency unexpectedly changed [up], now %d!\n",
		       engine->name, intel_rps_read_actual_frequency(rps));
		return -EINVAL;
	}

	if (!(rps->pm_iir & GEN6_PM_RP_UP_THRESHOLD)) {
		pr_err("%s: UP interrupt not recorded for spinner, pm_iir:%x, prev_up:%x, up_threshold:%x, up_ei:%x\n",
		       engine->name, rps->pm_iir,
		       intel_uncore_read(uncore, GEN6_RP_PREV_UP),
		       intel_uncore_read(uncore, GEN6_RP_UP_THRESHOLD),
		       intel_uncore_read(uncore, GEN6_RP_UP_EI));
		return -EINVAL;
	}

	return 0;
}

static int __rps_down_interrupt(struct intel_rps *rps,
				struct intel_engine_cs *engine)
{
	struct intel_uncore *uncore = engine->uncore;
	u32 timeout;

	mutex_lock(&rps->lock);
	GEM_BUG_ON(!rps->active);
	intel_rps_set(rps, rps->max_freq);
	mutex_unlock(&rps->lock);

	if (!(rps->pm_events & GEN6_PM_RP_DOWN_THRESHOLD)) {
		pr_err("%s: RPS did not register DOWN interrupt\n",
		       engine->name);
		return -EINVAL;
	}

	if (rps->last_freq != rps->max_freq) {
		pr_err("%s: RPS did not program max frequency\n",
		       engine->name);
		return -EINVAL;
	}

	timeout = intel_uncore_read(uncore, GEN6_RP_DOWN_EI);
	timeout = GT_PM_INTERVAL_TO_US(engine->i915, timeout);

	sleep_for_ei(rps, timeout);

	if (rps->cur_freq != rps->max_freq) {
		pr_err("%s: Frequency unexpectedly changed [down], now %d!\n",
		       engine->name,
		       intel_rps_read_actual_frequency(rps));
		return -EINVAL;
	}

	if (!(rps->pm_iir & (GEN6_PM_RP_DOWN_THRESHOLD | GEN6_PM_RP_DOWN_TIMEOUT))) {
		pr_err("%s: DOWN interrupt not recorded for idle, pm_iir:%x, prev_down:%x, down_threshold:%x, down_ei:%x [prev_up:%x, up_threshold:%x, up_ei:%x]\n",
		       engine->name, rps->pm_iir,
		       intel_uncore_read(uncore, GEN6_RP_PREV_DOWN),
		       intel_uncore_read(uncore, GEN6_RP_DOWN_THRESHOLD),
		       intel_uncore_read(uncore, GEN6_RP_DOWN_EI),
		       intel_uncore_read(uncore, GEN6_RP_PREV_UP),
		       intel_uncore_read(uncore, GEN6_RP_UP_THRESHOLD),
		       intel_uncore_read(uncore, GEN6_RP_UP_EI));
		return -EINVAL;
	}

	return 0;
}

int live_rps_interrupt(void *arg)
{
	struct intel_gt *gt = arg;
	struct intel_rps *rps = &gt->rps;
	void (*saved_work)(struct work_struct *wrk);
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	struct igt_spinner spin;
	u32 pm_events;
	int err = 0;

	/*
	 * First, let's check whether or not we are receiving interrupts.
	 */

	if (!rps->enabled || rps->max_freq <= rps->min_freq)
		return 0;

	intel_gt_pm_get(gt);
	pm_events = rps->pm_events;
	intel_gt_pm_put(gt);
	if (!pm_events) {
		pr_err("No RPS PM events registered, but RPS is enabled?\n");
		return -ENODEV;
	}

	if (igt_spinner_init(&spin, gt))
		return -ENOMEM;

	intel_gt_pm_wait_for_idle(gt);
	saved_work = rps->work.func;
	rps->work.func = dummy_rps_work;

	for_each_engine(engine, gt, id) {
		/* Keep the engine busy with a spinner; expect an UP! */
		if (pm_events & GEN6_PM_RP_UP_THRESHOLD) {
			intel_gt_pm_wait_for_idle(engine->gt);
			GEM_BUG_ON(rps->active);

			intel_engine_pm_get(engine);
			err = __rps_up_interrupt(rps, engine, &spin);
			intel_engine_pm_put(engine);
			if (err)
				goto out;

			intel_gt_pm_wait_for_idle(engine->gt);
		}

		/* Keep the engine awake but idle and check for DOWN */
		if (pm_events & GEN6_PM_RP_DOWN_THRESHOLD) {
			intel_engine_pm_get(engine);
			intel_rc6_disable(&gt->rc6);

			err = __rps_down_interrupt(rps, engine);

			intel_rc6_enable(&gt->rc6);
			intel_engine_pm_put(engine);
			if (err)
				goto out;
		}
	}

out:
	if (igt_flush_test(gt->i915))
		err = -EIO;

	igt_spinner_fini(&spin);

	intel_gt_pm_wait_for_idle(gt);
	rps->work.func = saved_work;

	return err;
}

static u64 __measure_power(int duration_ms)
{
	u64 dE, dt;

	dt = ktime_get();
	dE = librapl_energy_uJ();
	usleep_range(1000 * duration_ms, 2000 * duration_ms);
	dE = librapl_energy_uJ() - dE;
	dt = ktime_get() - dt;

	return div64_u64(1000 * 1000 * dE, dt);
}

static int cmp_u64(const void *A, const void *B)
{
	const u64 *a = A, *b = B;

	if (a < b)
		return -1;
	else if (a > b)
		return 1;
	else
		return 0;
}

static u64 measure_power_at(struct intel_rps *rps, int freq)
{
	u64 x[5];
	int i;

	mutex_lock(&rps->lock);
	GEM_BUG_ON(!rps->active);
	intel_rps_set(rps, freq);
	mutex_unlock(&rps->lock);

	msleep(20); /* more than enough time to stabilise! */

	i = read_cagf(rps);
	if (i != freq)
		pr_notice("Running at %x [%uMHz], not target %x [%uMHz]\n",
			  i, intel_gpu_freq(rps, i),
			  freq, intel_gpu_freq(rps, freq));

	for (i = 0; i < 5; i++)
		x[i] = __measure_power(5);

	/* A simple triangle filter for better result stability */
	sort(x, 5, sizeof(*x), cmp_u64, NULL);
	return div_u64(x[1] + 2 * x[2] + x[3], 4);
}

int live_rps_power(void *arg)
{
	struct intel_gt *gt = arg;
	struct intel_rps *rps = &gt->rps;
	void (*saved_work)(struct work_struct *wrk);
	struct intel_engine_cs *engine;
	enum intel_engine_id id;
	struct igt_spinner spin;
	int err = 0;

	/*
	 * Our fundamental assumption is that running at lower frequency
	 * actually saves power. Let's see if our RAPL measurement support
	 * that theory.
	 */

	if (!rps->enabled || rps->max_freq <= rps->min_freq)
		return 0;

	if (!librapl_energy_uJ())
		return 0;

	if (igt_spinner_init(&spin, gt))
		return -ENOMEM;

	intel_gt_pm_wait_for_idle(gt);
	saved_work = rps->work.func;
	rps->work.func = dummy_rps_work;

	for_each_engine(engine, gt, id) {
		struct i915_request *rq;
		u64 min, max;

		if (!intel_engine_can_store_dword(engine))
			continue;

		rq = igt_spinner_create_request(&spin,
						engine->kernel_context,
						MI_NOOP);
		if (IS_ERR(rq)) {
			err = PTR_ERR(rq);
			break;
		}

		i915_request_add(rq);

		if (!igt_wait_for_spinner(&spin, rq)) {
			pr_err("%s: RPS spinner did not start\n",
			       engine->name);
			intel_gt_set_wedged(engine->gt);
			err = -EIO;
			break;
		}

		max = measure_power_at(rps, rps->max_freq);
		min = measure_power_at(rps, rps->min_freq);

		igt_spinner_end(&spin);

		pr_info("%s: min:%llumW @ %uMHz, max:%llumW @ %uMHz\n",
			engine->name,
			min, intel_gpu_freq(rps, rps->min_freq),
			max, intel_gpu_freq(rps, rps->max_freq));
		if (11 * min > 10 * max) {
			pr_err("%s: did not conserve power when setting lower frequency!\n",
			       engine->name);
			err = -EINVAL;
			break;
		}

		if (igt_flush_test(gt->i915)) {
			err = -EIO;
			break;
		}
	}

	igt_spinner_fini(&spin);

	intel_gt_pm_wait_for_idle(gt);
	rps->work.func = saved_work;

	return err;
}