/*
 * 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 <linux/vgaarb.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.
 */

#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)

#include <linux/sort.h>

#define STACKDEPTH 8

static noinline depot_stack_handle_t __save_depot_stack(void)
{
        unsigned long entries[STACKDEPTH];
        unsigned int n;

        n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
        return stack_depot_save(entries, n, GFP_NOWAIT | __GFP_NOWARN);
}

static void __print_depot_stack(depot_stack_handle_t stack,
                                char *buf, int sz, int indent)
{
        unsigned long *entries;
        unsigned int nr_entries;

        nr_entries = stack_depot_fetch(stack, &entries);
        stack_trace_snprint(buf, sz, entries, nr_entries, indent);
}

static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
        spin_lock_init(&rpm->debug.lock);
}

static noinline depot_stack_handle_t
track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
        depot_stack_handle_t stack, *stacks;
        unsigned long flags;

        if (!rpm->available)
                return -1;

        stack = __save_depot_stack();
        if (!stack)
                return -1;

        spin_lock_irqsave(&rpm->debug.lock, flags);

        if (!rpm->debug.count)
                rpm->debug.last_acquire = stack;

        stacks = krealloc(rpm->debug.owners,
                          (rpm->debug.count + 1) * sizeof(*stacks),
                          GFP_NOWAIT | __GFP_NOWARN);
        if (stacks) {
                stacks[rpm->debug.count++] = stack;
                rpm->debug.owners = stacks;
        } else {
                stack = -1;
        }

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

        return stack;
}

static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
                                             depot_stack_handle_t stack)
{
        unsigned long flags, n;
        bool found = false;

        if (unlikely(stack == -1))
                return;

        spin_lock_irqsave(&rpm->debug.lock, flags);
        for (n = rpm->debug.count; n--; ) {
                if (rpm->debug.owners[n] == stack) {
                        memmove(rpm->debug.owners + n,
                                rpm->debug.owners + n + 1,
                                (--rpm->debug.count - n) * sizeof(stack));
                        found = true;
                        break;
                }
        }
        spin_unlock_irqrestore(&rpm->debug.lock, flags);

        if (WARN(!found,
                 "Unmatched wakeref (tracking %lu), count %u\n",
                 rpm->debug.count, atomic_read(&rpm->wakeref_count))) {
                char *buf;

                buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
                if (!buf)
                        return;

                __print_depot_stack(stack, buf, PAGE_SIZE, 2);
                DRM_DEBUG_DRIVER("wakeref %x from\n%s", stack, buf);

                stack = READ_ONCE(rpm->debug.last_release);
                if (stack) {
                        __print_depot_stack(stack, buf, PAGE_SIZE, 2);
                        DRM_DEBUG_DRIVER("wakeref last released at\n%s", buf);
                }

                kfree(buf);
        }
}

static int cmphandle(const void *_a, const void *_b)
{
        const depot_stack_handle_t * const a = _a, * const b = _b;

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

static void
__print_intel_runtime_pm_wakeref(struct drm_printer *p,
                                 const struct intel_runtime_pm_debug *dbg)
{
        unsigned long i;
        char *buf;

        buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
        if (!buf)
                return;

        if (dbg->last_acquire) {
                __print_depot_stack(dbg->last_acquire, buf, PAGE_SIZE, 2);
                drm_printf(p, "Wakeref last acquired:\n%s", buf);
        }

        if (dbg->last_release) {
                __print_depot_stack(dbg->last_release, buf, PAGE_SIZE, 2);
                drm_printf(p, "Wakeref last released:\n%s", buf);
        }

        drm_printf(p, "Wakeref count: %lu\n", dbg->count);

        sort(dbg->owners, dbg->count, sizeof(*dbg->owners), cmphandle, NULL);

        for (i = 0; i < dbg->count; i++) {
                depot_stack_handle_t stack = dbg->owners[i];
                unsigned long rep;

                rep = 1;
                while (i + 1 < dbg->count && dbg->owners[i + 1] == stack)
                        rep++, i++;
                __print_depot_stack(stack, buf, PAGE_SIZE, 2);
                drm_printf(p, "Wakeref x%lu taken at:\n%s", rep, buf);
        }

        kfree(buf);
}

static noinline void
__untrack_all_wakerefs(struct intel_runtime_pm_debug *debug,
                       struct intel_runtime_pm_debug *saved)
{
        *saved = *debug;

        debug->owners = NULL;
        debug->count = 0;
        debug->last_release = __save_depot_stack();
}

static void
dump_and_free_wakeref_tracking(struct intel_runtime_pm_debug *debug)
{
        if (debug->count) {
                struct drm_printer p = drm_debug_printer("i915");

                __print_intel_runtime_pm_wakeref(&p, debug);
        }

        kfree(debug->owners);
}

static noinline void
__intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
{
        struct intel_runtime_pm_debug dbg = {};
        unsigned long flags;

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

        __untrack_all_wakerefs(&rpm->debug, &dbg);
        spin_unlock_irqrestore(&rpm->debug.lock, flags);

        dump_and_free_wakeref_tracking(&dbg);
}

static noinline void
untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
{
        struct intel_runtime_pm_debug dbg = {};
        unsigned long flags;

        spin_lock_irqsave(&rpm->debug.lock, flags);
        __untrack_all_wakerefs(&rpm->debug, &dbg);
        spin_unlock_irqrestore(&rpm->debug.lock, flags);

        dump_and_free_wakeref_tracking(&dbg);
}

void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
                                    struct drm_printer *p)
{
        struct intel_runtime_pm_debug dbg = {};

        do {
                unsigned long alloc = dbg.count;
                depot_stack_handle_t *s;

                spin_lock_irq(&rpm->debug.lock);
                dbg.count = rpm->debug.count;
                if (dbg.count <= alloc) {
                        memcpy(dbg.owners,
                               rpm->debug.owners,
                               dbg.count * sizeof(*s));
                }
                dbg.last_acquire = rpm->debug.last_acquire;
                dbg.last_release = rpm->debug.last_release;
                spin_unlock_irq(&rpm->debug.lock);
                if (dbg.count <= alloc)
                        break;

                s = krealloc(dbg.owners,
                             dbg.count * sizeof(*s),
                             GFP_NOWAIT | __GFP_NOWARN);
                if (!s)
                        goto out;

                dbg.owners = s;
        } while (1);

        __print_intel_runtime_pm_wakeref(p, &dbg);

out:
        kfree(dbg.owners);
}

#else

static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
{
}

static depot_stack_handle_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 wref)
{
}

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)
{
        int ret;

        ret = pm_runtime_get_sync(rpm->kdev);
        WARN_ONCE(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_in_use - grab a runtime pm reference if device in use
 * @rpm: the intel_runtime_pm structure
 *
 * This function grabs a device-level runtime pm reference if the device is
 * already in use and ensures that it is powered up. It is illegal to try
 * and access the HW should intel_runtime_pm_get_if_in_use() report failure.
 *
 * 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.
 */
intel_wakeref_t intel_runtime_pm_get_if_in_use(struct intel_runtime_pm *rpm)
{
        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 (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_runtime_pm_get_noresume - 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).
 *
 * It will _not_ power up the device but instead only check that it's powered
 * on.  Therefore it is only valid to call this functions from contexts where
 * the device is known to be powered up and where trying to power it up would
 * result in hilarity and deadlocks. That pretty much means only the system
 * suspend/resume code where this is used to grab runtime pm references for
 * delayed setup down in work items.
 *
 * 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_wakelock_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 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_NEVER_SKIP);

        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);
                WARN(ret < 0, "pm_runtime_get_sync() failed: %d\n", ret);
        } else {
                pm_runtime_use_autosuspend(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 device *kdev = rpm->kdev;

        /* Transfer rpm ownership back to core */
        WARN(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)
{
        int count = atomic_read(&rpm->wakeref_count);

        WARN(count,
             "i915 raw-wakerefs=%d wakelocks=%d on cleanup\n",
             intel_rpm_raw_wakeref_count(count),
             intel_rpm_wakelock_count(count));

        untrack_all_intel_runtime_pm_wakerefs(rpm);
}

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

        rpm->kdev = kdev;
        rpm->available = HAS_RUNTIME_PM(i915);

        init_intel_runtime_pm_wakeref(rpm);
}