/*
 * Copyright © 2012-2014 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eugeni Dodonov <eugeni.dodonov@intel.com>
 *    Daniel Vetter <daniel.vetter@ffwll.ch>
 *
 */

#include <linux/pm_runtime.h>

#include <drm/drm_print.h>

#include "i915_drv.h"
#include "i915_trace.h"

/**
 * DOC: runtime pm
 *
 * The i915 driver supports dynamic enabling and disabling of entire hardware
 * blocks at runtime. This is especially important on the display side where
 * software is supposed to control many power gates manually on recent hardware,
 * since on the GT side a lot of the power management is done by the hardware.
 * But even there some manual control at the device level is required.
 *
 * Since i915 supports a diverse set of platforms with a unified codebase and
 * hardware engineers just love to shuffle functionality around between power
 * domains there's a sizeable amount of indirection required. This file provides
 * generic functions to the driver for grabbing and releasing references for
 * abstract power domains. It then maps those to the actual power wells
 * present for a given platform.
 */

static struct drm_i915_private *rpm_to_i915(struct intel_runtime_pm *rpm)
{
	return container_of(rpm, struct drm_i915_private, runtime_pm);
}

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)

static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
	ref_tracker_dir_init(&rpm->debug, INTEL_REFTRACK_DEAD_COUNT, dev_name(rpm->kdev));
}

static intel_wakeref_t
track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
	if (!rpm->available || rpm->no_wakeref_tracking)
		return -1;

	return intel_ref_tracker_alloc(&rpm->debug);
}

static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
					     intel_wakeref_t wakeref)
{
	if (!rpm->available || rpm->no_wakeref_tracking)
		return;

	intel_ref_tracker_free(&rpm->debug, wakeref);
}

static void untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
{
	ref_tracker_dir_exit(&rpm->debug);
}

static noinline void
__intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
{
	unsigned long flags;

	if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
					 &rpm->debug.lock,
					 flags))
		return;

	ref_tracker_dir_print_locked(&rpm->debug, INTEL_REFTRACK_PRINT_LIMIT);
	spin_unlock_irqrestore(&rpm->debug.lock, flags);
}

void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
				    struct drm_printer *p)
{
	intel_ref_tracker_show(&rpm->debug, p);
}

#else

static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
}

static intel_wakeref_t
track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
	return -1;
}

static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
					     intel_wakeref_t wakeref)
{
}

static void
__intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
{
	atomic_dec(&rpm->wakeref_count);
}

static void
untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
{
}

#endif

static void
intel_runtime_pm_acquire(struct intel_runtime_pm *rpm, bool wakelock)
{
	if (wakelock) {
		atomic_add(1 + INTEL_RPM_WAKELOCK_BIAS, &rpm->wakeref_count);
		assert_rpm_wakelock_held(rpm);
	} else {
		atomic_inc(&rpm->wakeref_count);
		assert_rpm_raw_wakeref_held(rpm);
	}
}

static void
intel_runtime_pm_release(struct intel_runtime_pm *rpm, int wakelock)
{
	if (wakelock) {
		assert_rpm_wakelock_held(rpm);
		atomic_sub(INTEL_RPM_WAKELOCK_BIAS, &rpm->wakeref_count);
	} else {
		assert_rpm_raw_wakeref_held(rpm);
	}

	__intel_wakeref_dec_and_check_tracking(rpm);
}

static intel_wakeref_t __intel_runtime_pm_get(struct intel_runtime_pm *rpm,
					      bool wakelock)
{
	struct drm_i915_private *i915 = rpm_to_i915(rpm);
	int ret;

	ret = pm_runtime_get_sync(rpm->kdev);
	drm_WARN_ONCE(&i915->drm, ret < 0,
		      "pm_runtime_get_sync() failed: %d\n", ret);

	intel_runtime_pm_acquire(rpm, wakelock);

	return track_intel_runtime_pm_wakeref(rpm);
}

/**
 * intel_runtime_pm_get_raw - grab a raw runtime pm reference
 * @rpm: the intel_runtime_pm structure
 *
 * This is the unlocked version of intel_display_power_is_enabled() and should
 * only be used from error capture and recovery code where deadlocks are
 * possible.
 * This function grabs a device-level runtime pm reference (mostly used for
 * asynchronous PM management from display code) and ensures that it is powered
 * up. Raw references are not considered during wakelock assert checks.
 *
 * Any runtime pm reference obtained by this function must have a symmetric
 * call to intel_runtime_pm_put_raw() to release the reference again.
 *
 * Returns: the wakeref cookie to pass to intel_runtime_pm_put_raw(), evaluates
 * as True if the wakeref was acquired, or False otherwise.
 */
intel_wakeref_t intel_runtime_pm_get_raw(struct intel_runtime_pm *rpm)
{
	return __intel_runtime_pm_get(rpm, false);
}

/**
 * intel_runtime_pm_get - grab a runtime pm reference
 * @rpm: the intel_runtime_pm structure
 *
 * This function grabs a device-level runtime pm reference (mostly used for GEM
 * code to ensure the GTT or GT is on) and ensures that it is powered up.
 *
 * Any runtime pm reference obtained by this function must have a symmetric
 * call to intel_runtime_pm_put() to release the reference again.
 *
 * Returns: the wakeref cookie to pass to intel_runtime_pm_put()
 */
intel_wakeref_t intel_runtime_pm_get(struct intel_runtime_pm *rpm)
{
	return __intel_runtime_pm_get(rpm, true);
}

/**
 * __intel_runtime_pm_get_if_active - grab a runtime pm reference if device is active
 * @rpm: the intel_runtime_pm structure
 * @ignore_usecount: get a ref even if dev->power.usage_count is 0
 *
 * This function grabs a device-level runtime pm reference if the device is
 * already active and ensures that it is powered up. It is illegal to try
 * and access the HW should intel_runtime_pm_get_if_active() report failure.
 *
 * If @ignore_usecount is true, a reference will be acquired even if there is no
 * user requiring the device to be powered up (dev->power.usage_count == 0).
 * If the function returns false in this case then it's guaranteed that the
 * device's runtime suspend hook has been called already or that it will be
 * called (and hence it's also guaranteed that the device's runtime resume
 * hook will be called eventually).
 *
 * Any runtime pm reference obtained by this function must have a symmetric
 * call to intel_runtime_pm_put() to release the reference again.
 *
 * Returns: the wakeref cookie to pass to intel_runtime_pm_put(), evaluates
 * as True if the wakeref was acquired, or False otherwise.
 */
static intel_wakeref_t __intel_runtime_pm_get_if_active(struct intel_runtime_pm *rpm,
							bool ignore_usecount)
{
	if (IS_ENABLED(CONFIG_PM)) {
		/*
		 * In cases runtime PM is disabled by the RPM core and we get
		 * an -EINVAL return value we are not supposed to call this
		 * function, since the power state is undefined. This applies
		 * atm to the late/early system suspend/resume handlers.
		 */
		if ((ignore_usecount &&
		     pm_runtime_get_if_active(rpm->kdev) <= 0) ||
		    (!ignore_usecount &&
		     pm_runtime_get_if_in_use(rpm->kdev) <= 0))
			return 0;
	}

	intel_runtime_pm_acquire(rpm, true);

	return track_intel_runtime_pm_wakeref(rpm);
}

intel_wakeref_t intel_runtime_pm_get_if_in_use(struct intel_runtime_pm *rpm)
{
	return __intel_runtime_pm_get_if_active(rpm, false);
}

intel_wakeref_t intel_runtime_pm_get_if_active(struct intel_runtime_pm *rpm)
{
	return __intel_runtime_pm_get_if_active(rpm, true);
}

/**
 * intel_runtime_pm_get_noresume - grab a runtime pm reference
 * @rpm: the intel_runtime_pm structure
 *
 * This function grabs a device-level runtime pm reference.
 *
 * It will _not_ resume the device but instead only get an extra wakeref.
 * Therefore it is only valid to call this functions from contexts where
 * the device is known to be active and with another wakeref previously hold.
 *
 * Any runtime pm reference obtained by this function must have a symmetric
 * call to intel_runtime_pm_put() to release the reference again.
 *
 * Returns: the wakeref cookie to pass to intel_runtime_pm_put()
 */
intel_wakeref_t intel_runtime_pm_get_noresume(struct intel_runtime_pm *rpm)
{
	assert_rpm_raw_wakeref_held(rpm);
	pm_runtime_get_noresume(rpm->kdev);

	intel_runtime_pm_acquire(rpm, true);

	return track_intel_runtime_pm_wakeref(rpm);
}

static void __intel_runtime_pm_put(struct intel_runtime_pm *rpm,
				   intel_wakeref_t wref,
				   bool wakelock)
{
	struct device *kdev = rpm->kdev;

	untrack_intel_runtime_pm_wakeref(rpm, wref);

	intel_runtime_pm_release(rpm, wakelock);

	pm_runtime_mark_last_busy(kdev);
	pm_runtime_put_autosuspend(kdev);
}

/**
 * intel_runtime_pm_put_raw - release a raw runtime pm reference
 * @rpm: the intel_runtime_pm structure
 * @wref: wakeref acquired for the reference that is being released
 *
 * This function drops the device-level runtime pm reference obtained by
 * intel_runtime_pm_get_raw() and might power down the corresponding
 * hardware block right away if this is the last reference.
 */
void
intel_runtime_pm_put_raw(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
{
	__intel_runtime_pm_put(rpm, wref, false);
}

/**
 * intel_runtime_pm_put_unchecked - release an unchecked runtime pm reference
 * @rpm: the intel_runtime_pm structure
 *
 * This function drops the device-level runtime pm reference obtained by
 * intel_runtime_pm_get() and might power down the corresponding
 * hardware block right away if this is the last reference.
 *
 * This function exists only for historical reasons and should be avoided in
 * new code, as the correctness of its use cannot be checked. Always use
 * intel_runtime_pm_put() instead.
 */
void intel_runtime_pm_put_unchecked(struct intel_runtime_pm *rpm)
{
	__intel_runtime_pm_put(rpm, -1, true);
}

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
/**
 * intel_runtime_pm_put - release a runtime pm reference
 * @rpm: the intel_runtime_pm structure
 * @wref: wakeref acquired for the reference that is being released
 *
 * This function drops the device-level runtime pm reference obtained by
 * intel_runtime_pm_get() and might power down the corresponding
 * hardware block right away if this is the last reference.
 */
void intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
{
	__intel_runtime_pm_put(rpm, wref, true);
}
#endif

/**
 * intel_runtime_pm_enable - enable runtime pm
 * @rpm: the intel_runtime_pm structure
 *
 * This function enables runtime pm at the end of the driver load sequence.
 *
 * Note that this function does currently not enable runtime pm for the
 * subordinate display power domains. That is done by
 * intel_power_domains_enable().
 */
void intel_runtime_pm_enable(struct intel_runtime_pm *rpm)
{
	struct drm_i915_private *i915 = rpm_to_i915(rpm);
	struct device *kdev = rpm->kdev;

	/*
	 * Disable the system suspend direct complete optimization, which can
	 * leave the device suspended skipping the driver's suspend handlers
	 * if the device was already runtime suspended. This is needed due to
	 * the difference in our runtime and system suspend sequence and
	 * becaue the HDA driver may require us to enable the audio power
	 * domain during system suspend.
	 */
	dev_pm_set_driver_flags(kdev, DPM_FLAG_NO_DIRECT_COMPLETE);

	pm_runtime_set_autosuspend_delay(kdev, 10000); /* 10s */
	pm_runtime_mark_last_busy(kdev);

	/*
	 * Take a permanent reference to disable the RPM functionality and drop
	 * it only when unloading the driver. Use the low level get/put helpers,
	 * so the driver's own RPM reference tracking asserts also work on
	 * platforms without RPM support.
	 */
	if (!rpm->available) {
		int ret;

		pm_runtime_dont_use_autosuspend(kdev);
		ret = pm_runtime_get_sync(kdev);
		drm_WARN(&i915->drm, ret < 0,
			 "pm_runtime_get_sync() failed: %d\n", ret);
	} else {
		pm_runtime_use_autosuspend(kdev);
	}

	/*
	 *  FIXME: Temp hammer to keep autosupend disable on lmem supported platforms.
	 *  As per PCIe specs 5.3.1.4.1, all iomem read write request over a PCIe
	 *  function will be unsupported in case PCIe endpoint function is in D3.
	 *  Let's keep i915 autosuspend control 'on' till we fix all known issue
	 *  with lmem access in D3.
	 */
	if (!IS_DGFX(i915))
		pm_runtime_allow(kdev);

	/*
	 * The core calls the driver load handler with an RPM reference held.
	 * We drop that here and will reacquire it during unloading in
	 * intel_power_domains_fini().
	 */
	pm_runtime_put_autosuspend(kdev);
}

void intel_runtime_pm_disable(struct intel_runtime_pm *rpm)
{
	struct drm_i915_private *i915 = rpm_to_i915(rpm);
	struct device *kdev = rpm->kdev;

	/* Transfer rpm ownership back to core */
	drm_WARN(&i915->drm, pm_runtime_get_sync(kdev) < 0,
		 "Failed to pass rpm ownership back to core\n");

	pm_runtime_dont_use_autosuspend(kdev);

	if (!rpm->available)
		pm_runtime_put(kdev);
}

void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm)
{
	struct drm_i915_private *i915 = rpm_to_i915(rpm);
	int count = atomic_read(&rpm->wakeref_count);

	intel_wakeref_auto_fini(&rpm->userfault_wakeref);

	drm_WARN(&i915->drm, count,
		 "i915 raw-wakerefs=%d wakelocks=%d on cleanup\n",
		 intel_rpm_raw_wakeref_count(count),
		 intel_rpm_wakelock_count(count));
}

void intel_runtime_pm_driver_last_release(struct intel_runtime_pm *rpm)
{
	intel_runtime_pm_driver_release(rpm);
	untrack_all_intel_runtime_pm_wakerefs(rpm);
}

void intel_runtime_pm_init_early(struct intel_runtime_pm *rpm)
{
	struct drm_i915_private *i915 = rpm_to_i915(rpm);
	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
	struct device *kdev = &pdev->dev;

	rpm->kdev = kdev;
	rpm->available = HAS_RUNTIME_PM(i915);
	atomic_set(&rpm->wakeref_count, 0);

	init_intel_runtime_pm_wakeref(rpm);
	INIT_LIST_HEAD(&rpm->lmem_userfault_list);
	spin_lock_init(&rpm->lmem_userfault_lock);
	intel_wakeref_auto_init(&rpm->userfault_wakeref, i915);
}