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

#include <linux/kobject.h>
#include <linux/sysfs.h>

#include "i915_drv.h"
#include "intel_engine.h"
#include "intel_engine_heartbeat.h"
#include "sysfs_engines.h"

struct kobj_engine {
        struct kobject base;
        struct intel_engine_cs *engine;
};

static struct intel_engine_cs *kobj_to_engine(struct kobject *kobj)
{
        return container_of(kobj, struct kobj_engine, base)->engine;
}

static ssize_t
name_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%s\n", kobj_to_engine(kobj)->name);
}

static struct kobj_attribute name_attr =
__ATTR(name, 0444, name_show, NULL);

static ssize_t
class_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_class);
}

static struct kobj_attribute class_attr =
__ATTR(class, 0444, class_show, NULL);

static ssize_t
inst_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", kobj_to_engine(kobj)->uabi_instance);
}

static struct kobj_attribute inst_attr =
__ATTR(instance, 0444, inst_show, NULL);

static ssize_t
mmio_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "0x%x\n", kobj_to_engine(kobj)->mmio_base);
}

static struct kobj_attribute mmio_attr =
__ATTR(mmio_base, 0444, mmio_show, NULL);

static const char * const vcs_caps[] = {
        [ilog2(I915_VIDEO_CLASS_CAPABILITY_HEVC)] = "hevc",
        [ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
};

static const char * const vecs_caps[] = {
        [ilog2(I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC)] = "sfc",
};

static ssize_t repr_trim(char *buf, ssize_t len)
{
        /* Trim off the trailing space and replace with a newline */
        if (len > PAGE_SIZE)
                len = PAGE_SIZE;
        if (len > 0)
                buf[len - 1] = '\n';

        return len;
}

static ssize_t
__caps_show(struct intel_engine_cs *engine,
            unsigned long caps, char *buf, bool show_unknown)
{
        const char * const *repr;
        int count, n;
        ssize_t len;

        switch (engine->class) {
        case VIDEO_DECODE_CLASS:
                repr = vcs_caps;
                count = ARRAY_SIZE(vcs_caps);
                break;

        case VIDEO_ENHANCEMENT_CLASS:
                repr = vecs_caps;
                count = ARRAY_SIZE(vecs_caps);
                break;

        default:
                repr = NULL;
                count = 0;
                break;
        }
        GEM_BUG_ON(count > BITS_PER_LONG);

        len = 0;
        for_each_set_bit(n, &caps, show_unknown ? BITS_PER_LONG : count) {
                if (n >= count || !repr[n]) {
                        if (GEM_WARN_ON(show_unknown))
                                len += snprintf(buf + len, PAGE_SIZE - len,
                                                "[%x] ", n);
                } else {
                        len += snprintf(buf + len, PAGE_SIZE - len,
                                        "%s ", repr[n]);
                }
                if (GEM_WARN_ON(len >= PAGE_SIZE))
                        break;
        }
        return repr_trim(buf, len);
}

static ssize_t
caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return __caps_show(engine, engine->uabi_capabilities, buf, true);
}

static struct kobj_attribute caps_attr =
__ATTR(capabilities, 0444, caps_show, NULL);

static ssize_t
all_caps_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        return __caps_show(kobj_to_engine(kobj), -1, buf, false);
}

static struct kobj_attribute all_caps_attr =
__ATTR(known_capabilities, 0444, all_caps_show, NULL);

static ssize_t
max_spin_store(struct kobject *kobj, struct kobj_attribute *attr,
               const char *buf, size_t count)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);
        unsigned long long duration;
        int err;

        /*
         * When waiting for a request, if is it currently being executed
         * on the GPU, we busywait for a short while before sleeping. The
         * premise is that most requests are short, and if it is already
         * executing then there is a good chance that it will complete
         * before we can setup the interrupt handler and go to sleep.
         * We try to offset the cost of going to sleep, by first spinning
         * on the request -- if it completed in less time than it would take
         * to go sleep, process the interrupt and return back to the client,
         * then we have saved the client some latency, albeit at the cost
         * of spinning on an expensive CPU core.
         *
         * While we try to avoid waiting at all for a request that is unlikely
         * to complete, deciding how long it is worth spinning is for is an
         * arbitrary decision: trading off power vs latency.
         */

        err = kstrtoull(buf, 0, &duration);
        if (err)
                return err;

        if (duration > jiffies_to_nsecs(2))
                return -EINVAL;

        WRITE_ONCE(engine->props.max_busywait_duration_ns, duration);

        return count;
}

static ssize_t
max_spin_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->props.max_busywait_duration_ns);
}

static struct kobj_attribute max_spin_attr =
__ATTR(max_busywait_duration_ns, 0644, max_spin_show, max_spin_store);

static ssize_t
max_spin_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->defaults.max_busywait_duration_ns);
}

static struct kobj_attribute max_spin_def =
__ATTR(max_busywait_duration_ns, 0444, max_spin_default, NULL);

static ssize_t
timeslice_store(struct kobject *kobj, struct kobj_attribute *attr,
                const char *buf, size_t count)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);
        unsigned long long duration;
        int err;

        /*
         * Execlists uses a scheduling quantum (a timeslice) to alternate
         * execution between ready-to-run contexts of equal priority. This
         * ensures that all users (though only if they of equal importance)
         * have the opportunity to run and prevents livelocks where contexts
         * may have implicit ordering due to userspace semaphores.
         */

        err = kstrtoull(buf, 0, &duration);
        if (err)
                return err;

        if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
                return -EINVAL;

        WRITE_ONCE(engine->props.timeslice_duration_ms, duration);

        if (execlists_active(&engine->execlists))
                set_timer_ms(&engine->execlists.timer, duration);

        return count;
}

static ssize_t
timeslice_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->props.timeslice_duration_ms);
}

static struct kobj_attribute timeslice_duration_attr =
__ATTR(timeslice_duration_ms, 0644, timeslice_show, timeslice_store);

static ssize_t
timeslice_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->defaults.timeslice_duration_ms);
}

static struct kobj_attribute timeslice_duration_def =
__ATTR(timeslice_duration_ms, 0444, timeslice_default, NULL);

static ssize_t
stop_store(struct kobject *kobj, struct kobj_attribute *attr,
           const char *buf, size_t count)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);
        unsigned long long duration;
        int err;

        /*
         * When we allow ourselves to sleep before a GPU reset after disabling
         * submission, even for a few milliseconds, gives an innocent context
         * the opportunity to clear the GPU before the reset occurs. However,
         * how long to sleep depends on the typical non-preemptible duration
         * (a similar problem to determining the ideal preempt-reset timeout
         * or even the heartbeat interval).
         */

        err = kstrtoull(buf, 0, &duration);
        if (err)
                return err;

        if (duration > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
                return -EINVAL;

        WRITE_ONCE(engine->props.stop_timeout_ms, duration);
        return count;
}

static ssize_t
stop_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->props.stop_timeout_ms);
}

static struct kobj_attribute stop_timeout_attr =
__ATTR(stop_timeout_ms, 0644, stop_show, stop_store);

static ssize_t
stop_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->defaults.stop_timeout_ms);
}

static struct kobj_attribute stop_timeout_def =
__ATTR(stop_timeout_ms, 0444, stop_default, NULL);

static ssize_t
preempt_timeout_store(struct kobject *kobj, struct kobj_attribute *attr,
                      const char *buf, size_t count)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);
        unsigned long long timeout;
        int err;

        /*
         * After initialising a preemption request, we give the current
         * resident a small amount of time to vacate the GPU. The preemption
         * request is for a higher priority context and should be immediate to
         * maintain high quality of service (and avoid priority inversion).
         * However, the preemption granularity of the GPU can be quite coarse
         * and so we need a compromise.
         */

        err = kstrtoull(buf, 0, &timeout);
        if (err)
                return err;

        if (timeout > jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
                return -EINVAL;

        WRITE_ONCE(engine->props.preempt_timeout_ms, timeout);

        if (READ_ONCE(engine->execlists.pending[0]))
                set_timer_ms(&engine->execlists.preempt, timeout);

        return count;
}

static ssize_t
preempt_timeout_show(struct kobject *kobj, struct kobj_attribute *attr,
                     char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->props.preempt_timeout_ms);
}

static struct kobj_attribute preempt_timeout_attr =
__ATTR(preempt_timeout_ms, 0644, preempt_timeout_show, preempt_timeout_store);

static ssize_t
preempt_timeout_default(struct kobject *kobj, struct kobj_attribute *attr,
                        char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->defaults.preempt_timeout_ms);
}

static struct kobj_attribute preempt_timeout_def =
__ATTR(preempt_timeout_ms, 0444, preempt_timeout_default, NULL);

static ssize_t
heartbeat_store(struct kobject *kobj, struct kobj_attribute *attr,
                const char *buf, size_t count)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);
        unsigned long long delay;
        int err;

        /*
         * We monitor the health of the system via periodic heartbeat pulses.
         * The pulses also provide the opportunity to perform garbage
         * collection.  However, we interpret an incomplete pulse (a missed
         * heartbeat) as an indication that the system is no longer responsive,
         * i.e. hung, and perform an engine or full GPU reset. Given that the
         * preemption granularity can be very coarse on a system, the optimal
         * value for any workload is unknowable!
         */

        err = kstrtoull(buf, 0, &delay);
        if (err)
                return err;

        if (delay >= jiffies_to_msecs(MAX_SCHEDULE_TIMEOUT))
                return -EINVAL;

        err = intel_engine_set_heartbeat(engine, delay);
        if (err)
                return err;

        return count;
}

static ssize_t
heartbeat_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->props.heartbeat_interval_ms);
}

static struct kobj_attribute heartbeat_interval_attr =
__ATTR(heartbeat_interval_ms, 0644, heartbeat_show, heartbeat_store);

static ssize_t
heartbeat_default(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
{
        struct intel_engine_cs *engine = kobj_to_engine(kobj);

        return sprintf(buf, "%lu\n", engine->defaults.heartbeat_interval_ms);
}

static struct kobj_attribute heartbeat_interval_def =
__ATTR(heartbeat_interval_ms, 0444, heartbeat_default, NULL);

static void kobj_engine_release(struct kobject *kobj)
{
        kfree(kobj);
}

static struct kobj_type kobj_engine_type = {
        .release = kobj_engine_release,
        .sysfs_ops = &kobj_sysfs_ops
};

static struct kobject *
kobj_engine(struct kobject *dir, struct intel_engine_cs *engine)
{
        struct kobj_engine *ke;

        ke = kzalloc(sizeof(*ke), GFP_KERNEL);
        if (!ke)
                return NULL;

        kobject_init(&ke->base, &kobj_engine_type);
        ke->engine = engine;

        if (kobject_add(&ke->base, dir, "%s", engine->name)) {
                kobject_put(&ke->base);
                return NULL;
        }

        /* xfer ownership to sysfs tree */
        return &ke->base;
}

static void add_defaults(struct kobj_engine *parent)
{
        static const struct attribute *files[] = {
                &max_spin_def.attr,
                &stop_timeout_def.attr,
#if CONFIG_DRM_I915_HEARTBEAT_INTERVAL
                &heartbeat_interval_def.attr,
#endif
                NULL
        };
        struct kobj_engine *ke;

        ke = kzalloc(sizeof(*ke), GFP_KERNEL);
        if (!ke)
                return;

        kobject_init(&ke->base, &kobj_engine_type);
        ke->engine = parent->engine;

        if (kobject_add(&ke->base, &parent->base, "%s", ".defaults")) {
                kobject_put(&ke->base);
                return;
        }

        if (sysfs_create_files(&ke->base, files))
                return;

        if (intel_engine_has_timeslices(ke->engine) &&
            sysfs_create_file(&ke->base, &timeslice_duration_def.attr))
                return;

        if (intel_engine_has_preempt_reset(ke->engine) &&
            sysfs_create_file(&ke->base, &preempt_timeout_def.attr))
                return;
}

void intel_engines_add_sysfs(struct drm_i915_private *i915)
{
        static const struct attribute *files[] = {
                &name_attr.attr,
                &class_attr.attr,
                &inst_attr.attr,
                &mmio_attr.attr,
                &caps_attr.attr,
                &all_caps_attr.attr,
                &max_spin_attr.attr,
                &stop_timeout_attr.attr,
#if CONFIG_DRM_I915_HEARTBEAT_INTERVAL
                &heartbeat_interval_attr.attr,
#endif
                NULL
        };

        struct device *kdev = i915->drm.primary->kdev;
        struct intel_engine_cs *engine;
        struct kobject *dir;

        dir = kobject_create_and_add("engine", &kdev->kobj);
        if (!dir)
                return;

        for_each_uabi_engine(engine, i915) {
                struct kobject *kobj;

                kobj = kobj_engine(dir, engine);
                if (!kobj)
                        goto err_engine;

                if (sysfs_create_files(kobj, files))
                        goto err_object;

                if (intel_engine_has_timeslices(engine) &&
                    sysfs_create_file(kobj, &timeslice_duration_attr.attr))
                        goto err_engine;

                if (intel_engine_has_preempt_reset(engine) &&
                    sysfs_create_file(kobj, &preempt_timeout_attr.attr))
                        goto err_engine;

                add_defaults(container_of(kobj, struct kobj_engine, base));

                if (0) {
err_object:
                        kobject_put(kobj);
err_engine:
                        dev_err(kdev, "Failed to add sysfs engine '%s'\n",
                                engine->name);
                        break;
                }
        }
}