// SPDX-License-Identifier: GPL-2.0-only
/*
 * LED Triggers Core
 *
 * Copyright 2005-2007 Openedhand Ltd.
 *
 * Author: Richard Purdie <rpurdie@openedhand.com>
 */

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/timer.h>
#include <linux/rwsem.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include "leds.h"

/*
 * Nests outside led_cdev->trigger_lock
 */
static DECLARE_RWSEM(triggers_list_lock);
static LIST_HEAD(trigger_list);

 /* Used by LED Class */

static inline bool
trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
{
        return !trig->trigger_type || trig->trigger_type == led_cdev->trigger_type;
}

ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
                          const struct bin_attribute *bin_attr, char *buf,
                          loff_t pos, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct led_classdev *led_cdev = dev_get_drvdata(dev);
        struct led_trigger *trig;
        int ret = count;

        mutex_lock(&led_cdev->led_access);

        if (led_sysfs_is_disabled(led_cdev)) {
                ret = -EBUSY;
                goto unlock;
        }

        if (sysfs_streq(buf, "none")) {
                led_trigger_remove(led_cdev);
                goto unlock;
        }

        if (sysfs_streq(buf, "default")) {
                led_trigger_set_default(led_cdev);
                goto unlock;
        }

        down_read(&triggers_list_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
                if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
                        down_write(&led_cdev->trigger_lock);
                        led_trigger_set(led_cdev, trig);
                        up_write(&led_cdev->trigger_lock);

                        up_read(&triggers_list_lock);
                        goto unlock;
                }
        }
        /* we come here only if buf matches no trigger */
        ret = -EINVAL;
        up_read(&triggers_list_lock);

unlock:
        mutex_unlock(&led_cdev->led_access);
        return ret;
}
EXPORT_SYMBOL_GPL(led_trigger_write);

__printf(3, 4)
static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
{
        va_list args;
        int i;

        va_start(args, fmt);
        if (size <= 0)
                i = vsnprintf(NULL, 0, fmt, args);
        else
                i = vscnprintf(buf, size, fmt, args);
        va_end(args);

        return i;
}

static int led_trigger_format(char *buf, size_t size,
                              struct led_classdev *led_cdev)
{
        struct led_trigger *trig;
        int len = led_trigger_snprintf(buf, size, "%s",
                                       led_cdev->trigger ? "none" : "[none]");

        if (led_cdev->default_trigger)
                len += led_trigger_snprintf(buf + len, size - len, " default");

        list_for_each_entry(trig, &trigger_list, next_trig) {
                bool hit;

                if (!trigger_relevant(led_cdev, trig))
                        continue;

                hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);

                len += led_trigger_snprintf(buf + len, size - len,
                                            " %s%s%s", hit ? "[" : "",
                                            trig->name, hit ? "]" : "");
        }

        len += led_trigger_snprintf(buf + len, size - len, "\n");

        return len;
}

/*
 * It was stupid to create 10000 cpu triggers, but we are stuck with it now.
 * Don't make that mistake again. We work around it here by creating binary
 * attribute, which is not limited by length. This is _not_ good design, do not
 * copy it.
 */
ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
                        const struct bin_attribute *attr, char *buf,
                        loff_t pos, size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct led_classdev *led_cdev = dev_get_drvdata(dev);
        void *data;
        int len;

        down_read(&triggers_list_lock);
        down_read(&led_cdev->trigger_lock);

        len = led_trigger_format(NULL, 0, led_cdev);
        data = kvmalloc(len + 1, GFP_KERNEL);
        if (!data) {
                up_read(&led_cdev->trigger_lock);
                up_read(&triggers_list_lock);
                return -ENOMEM;
        }
        len = led_trigger_format(data, len + 1, led_cdev);

        up_read(&led_cdev->trigger_lock);
        up_read(&triggers_list_lock);

        len = memory_read_from_buffer(buf, count, &pos, data, len);

        kvfree(data);

        return len;
}
EXPORT_SYMBOL_GPL(led_trigger_read);

/* Caller must ensure led_cdev->trigger_lock held */
int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
{
        char *event = NULL;
        char *envp[2];
        const char *name;
        int ret;

        if (!led_cdev->trigger && !trig)
                return 0;

        name = trig ? trig->name : "none";
        event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);

        /* Remove any existing trigger */
        if (led_cdev->trigger) {
                spin_lock(&led_cdev->trigger->leddev_list_lock);
                list_del_rcu(&led_cdev->trig_list);
                spin_unlock(&led_cdev->trigger->leddev_list_lock);

                /* ensure it's no longer visible on the led_cdevs list */
                synchronize_rcu();

                cancel_work_sync(&led_cdev->set_brightness_work);
                led_stop_software_blink(led_cdev);
                device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
                if (led_cdev->trigger->deactivate)
                        led_cdev->trigger->deactivate(led_cdev);
                led_cdev->trigger = NULL;
                led_cdev->trigger_data = NULL;
                led_cdev->activated = false;
                led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
                led_set_brightness(led_cdev, LED_OFF);
        }
        if (trig) {
                spin_lock(&trig->leddev_list_lock);
                list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
                spin_unlock(&trig->leddev_list_lock);
                led_cdev->trigger = trig;

                /*
                 * Some activate() calls use led_trigger_event() to initialize
                 * the brightness of the LED for which the trigger is being set.
                 * Ensure the led_cdev is visible on trig->led_cdevs for this.
                 */
                synchronize_rcu();

                /*
                 * If "set brightness to 0" is pending in workqueue,
                 * we don't want that to be reordered after ->activate()
                 */
                flush_work(&led_cdev->set_brightness_work);

                ret = 0;
                if (trig->activate)
                        ret = trig->activate(led_cdev);
                else
                        led_set_brightness(led_cdev, trig->brightness);
                if (ret)
                        goto err_activate;

                ret = device_add_groups(led_cdev->dev, trig->groups);
                if (ret) {
                        dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
                        goto err_add_groups;
                }
        }

        if (event) {
                envp[0] = event;
                envp[1] = NULL;
                if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
                        dev_err(led_cdev->dev,
                                "%s: Error sending uevent\n", __func__);
                kfree(event);
        }

        return 0;

err_add_groups:

        if (trig->deactivate)
                trig->deactivate(led_cdev);
err_activate:

        spin_lock(&led_cdev->trigger->leddev_list_lock);
        list_del_rcu(&led_cdev->trig_list);
        spin_unlock(&led_cdev->trigger->leddev_list_lock);
        synchronize_rcu();
        led_cdev->trigger = NULL;
        led_cdev->trigger_data = NULL;
        led_set_brightness(led_cdev, LED_OFF);
        kfree(event);

        return ret;
}
EXPORT_SYMBOL_GPL(led_trigger_set);

void led_trigger_remove(struct led_classdev *led_cdev)
{
        down_write(&led_cdev->trigger_lock);
        led_trigger_set(led_cdev, NULL);
        up_write(&led_cdev->trigger_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_remove);

static bool led_match_default_trigger(struct led_classdev *led_cdev,
                                      struct led_trigger *trig)
{
        if (!strcmp(led_cdev->default_trigger, trig->name) &&
            trigger_relevant(led_cdev, trig)) {
                led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
                led_trigger_set(led_cdev, trig);
                return true;
        }

        return false;
}

void led_trigger_set_default(struct led_classdev *led_cdev)
{
        struct led_trigger *trig;
        bool found = false;

        if (!led_cdev->default_trigger)
                return;

        if (!strcmp(led_cdev->default_trigger, "none")) {
                led_trigger_remove(led_cdev);
                return;
        }

        down_read(&triggers_list_lock);
        down_write(&led_cdev->trigger_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
                found = led_match_default_trigger(led_cdev, trig);
                if (found)
                        break;
        }
        up_write(&led_cdev->trigger_lock);
        up_read(&triggers_list_lock);

        /*
         * If default trigger wasn't found, maybe trigger module isn't loaded yet.
         * Once loaded it will re-probe with all led_cdev's.
         */
        if (!found)
                request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
}
EXPORT_SYMBOL_GPL(led_trigger_set_default);

/* LED Trigger Interface */

int led_trigger_register(struct led_trigger *trig)
{
        struct led_classdev *led_cdev;
        struct led_trigger *_trig;

        spin_lock_init(&trig->leddev_list_lock);
        INIT_LIST_HEAD(&trig->led_cdevs);

        down_write(&triggers_list_lock);
        /* Make sure the trigger's name isn't already in use */
        list_for_each_entry(_trig, &trigger_list, next_trig) {
                if (!strcmp(_trig->name, trig->name) &&
                    (trig->trigger_type == _trig->trigger_type ||
                     !trig->trigger_type || !_trig->trigger_type)) {
                        up_write(&triggers_list_lock);
                        return -EEXIST;
                }
        }
        /* Add to the list of led triggers */
        list_add_tail(&trig->next_trig, &trigger_list);
        up_write(&triggers_list_lock);

        /* Register with any LEDs that have this as a default trigger */
        down_read(&leds_list_lock);
        list_for_each_entry(led_cdev, &leds_list, node) {
                down_write(&led_cdev->trigger_lock);
                if (!led_cdev->trigger && led_cdev->default_trigger)
                        led_match_default_trigger(led_cdev, trig);
                up_write(&led_cdev->trigger_lock);
        }
        up_read(&leds_list_lock);

        return 0;
}
EXPORT_SYMBOL_GPL(led_trigger_register);

void led_trigger_unregister(struct led_trigger *trig)
{
        struct led_classdev *led_cdev;

        if (list_empty_careful(&trig->next_trig))
                return;

        /* Remove from the list of led triggers */
        down_write(&triggers_list_lock);
        list_del_init(&trig->next_trig);
        up_write(&triggers_list_lock);

        /* Remove anyone actively using this trigger */
        down_read(&leds_list_lock);
        list_for_each_entry(led_cdev, &leds_list, node) {
                down_write(&led_cdev->trigger_lock);
                if (led_cdev->trigger == trig)
                        led_trigger_set(led_cdev, NULL);
                up_write(&led_cdev->trigger_lock);
        }
        up_read(&leds_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister);

static void devm_led_trigger_release(struct device *dev, void *res)
{
        led_trigger_unregister(*(struct led_trigger **)res);
}

int devm_led_trigger_register(struct device *dev,
                              struct led_trigger *trig)
{
        struct led_trigger **dr;
        int rc;

        dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
                          GFP_KERNEL);
        if (!dr)
                return -ENOMEM;

        *dr = trig;

        rc = led_trigger_register(trig);
        if (rc)
                devres_free(dr);
        else
                devres_add(dev, dr);

        return rc;
}
EXPORT_SYMBOL_GPL(devm_led_trigger_register);

/* Simple LED Trigger Interface */

void led_trigger_event(struct led_trigger *trig,
                        enum led_brightness brightness)
{
        struct led_classdev *led_cdev;

        if (!trig)
                return;

        trig->brightness = brightness;

        rcu_read_lock();
        list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
                led_set_brightness(led_cdev, brightness);
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(led_trigger_event);

void led_mc_trigger_event(struct led_trigger *trig,
                          unsigned int *intensity_value, unsigned int num_colors,
                          enum led_brightness brightness)
{
        struct led_classdev *led_cdev;

        if (!trig)
                return;

        rcu_read_lock();
        list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
                if (!(led_cdev->flags & LED_MULTI_COLOR))
                        continue;

                led_mc_set_brightness(led_cdev, intensity_value, num_colors, brightness);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(led_mc_trigger_event);

static void led_trigger_blink_setup(struct led_trigger *trig,
                             unsigned long delay_on,
                             unsigned long delay_off,
                             int oneshot,
                             int invert)
{
        struct led_classdev *led_cdev;

        if (!trig)
                return;

        rcu_read_lock();
        list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
                if (oneshot)
                        led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
                                              invert);
                else
                        led_blink_set_nosleep(led_cdev, delay_on, delay_off);
        }
        rcu_read_unlock();
}

void led_trigger_blink(struct led_trigger *trig,
                       unsigned long delay_on,
                       unsigned long delay_off)
{
        led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
}
EXPORT_SYMBOL_GPL(led_trigger_blink);

void led_trigger_blink_oneshot(struct led_trigger *trig,
                               unsigned long delay_on,
                               unsigned long delay_off,
                               int invert)
{
        led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
}
EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);

void led_trigger_register_simple(const char *name, struct led_trigger **tp)
{
        struct led_trigger *trig;
        int err;

        trig = kzalloc_obj(struct led_trigger);

        if (trig) {
                trig->name = name;
                err = led_trigger_register(trig);
                if (err < 0) {
                        kfree(trig);
                        trig = NULL;
                        pr_warn("LED trigger %s failed to register (%d)\n",
                                name, err);
                }
        } else {
                pr_warn("LED trigger %s failed to register (no memory)\n",
                        name);
        }
        *tp = trig;
}
EXPORT_SYMBOL_GPL(led_trigger_register_simple);

void led_trigger_unregister_simple(struct led_trigger *trig)
{
        if (trig)
                led_trigger_unregister(trig);
        kfree(trig);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);