/*
 * V4L2 asynchronous subdevice registration API
 *
 * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>

#include <media/v4l2-async.h>
#include <media/v4l2-device.h>
#include <media/v4l2-subdev.h>

static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
{
#if IS_ENABLED(CONFIG_I2C)
        struct i2c_client *client = i2c_verify_client(sd->dev);
        return client &&
                asd->match.i2c.adapter_id == client->adapter->nr &&
                asd->match.i2c.address == client->addr;
#else
        return false;
#endif
}

static bool match_devname(struct v4l2_subdev *sd,
                          struct v4l2_async_subdev *asd)
{
        return !strcmp(asd->match.device_name.name, dev_name(sd->dev));
}

static bool match_of(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
{
        return sd->of_node == asd->match.of.node;
}

static bool match_custom(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
{
        if (!asd->match.custom.match)
                /* Match always */
                return true;

        return asd->match.custom.match(sd->dev, asd);
}

static LIST_HEAD(subdev_list);
static LIST_HEAD(notifier_list);
static DEFINE_MUTEX(list_lock);

static struct v4l2_async_subdev *v4l2_async_belongs(struct v4l2_async_notifier *notifier,
                                                    struct v4l2_subdev *sd)
{
        bool (*match)(struct v4l2_subdev *, struct v4l2_async_subdev *);
        struct v4l2_async_subdev *asd;

        list_for_each_entry(asd, &notifier->waiting, list) {
                /* bus_type has been verified valid before */
                switch (asd->match_type) {
                case V4L2_ASYNC_MATCH_CUSTOM:
                        match = match_custom;
                        break;
                case V4L2_ASYNC_MATCH_DEVNAME:
                        match = match_devname;
                        break;
                case V4L2_ASYNC_MATCH_I2C:
                        match = match_i2c;
                        break;
                case V4L2_ASYNC_MATCH_OF:
                        match = match_of;
                        break;
                default:
                        /* Cannot happen, unless someone breaks us */
                        WARN_ON(true);
                        return NULL;
                }

                /* match cannot be NULL here */
                if (match(sd, asd))
                        return asd;
        }

        return NULL;
}

static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
                                  struct v4l2_subdev *sd,
                                  struct v4l2_async_subdev *asd)
{
        int ret;

        /* Remove from the waiting list */
        list_del(&asd->list);
        sd->asd = asd;
        sd->notifier = notifier;

        if (notifier->bound) {
                ret = notifier->bound(notifier, sd, asd);
                if (ret < 0)
                        return ret;
        }
        /* Move from the global subdevice list to notifier's done */
        list_move(&sd->async_list, &notifier->done);

        ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
        if (ret < 0) {
                if (notifier->unbind)
                        notifier->unbind(notifier, sd, asd);
                return ret;
        }

        if (list_empty(&notifier->waiting) && notifier->complete)
                return notifier->complete(notifier);

        return 0;
}

static void v4l2_async_cleanup(struct v4l2_subdev *sd)
{
        v4l2_device_unregister_subdev(sd);
        /* Subdevice driver will reprobe and put the subdev back onto the list */
        list_del_init(&sd->async_list);
        sd->asd = NULL;
        sd->dev = NULL;
}

int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
                                 struct v4l2_async_notifier *notifier)
{
        struct v4l2_subdev *sd, *tmp;
        struct v4l2_async_subdev *asd;
        int i;

        if (!notifier->num_subdevs || notifier->num_subdevs > V4L2_MAX_SUBDEVS)
                return -EINVAL;

        notifier->v4l2_dev = v4l2_dev;
        INIT_LIST_HEAD(&notifier->waiting);
        INIT_LIST_HEAD(&notifier->done);

        for (i = 0; i < notifier->num_subdevs; i++) {
                asd = notifier->subdevs[i];

                switch (asd->match_type) {
                case V4L2_ASYNC_MATCH_CUSTOM:
                case V4L2_ASYNC_MATCH_DEVNAME:
                case V4L2_ASYNC_MATCH_I2C:
                case V4L2_ASYNC_MATCH_OF:
                        break;
                default:
                        dev_err(notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL,
                                "Invalid match type %u on %p\n",
                                asd->match_type, asd);
                        return -EINVAL;
                }
                list_add_tail(&asd->list, &notifier->waiting);
        }

        mutex_lock(&list_lock);

        /* Keep also completed notifiers on the list */
        list_add(&notifier->list, &notifier_list);

        list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
                int ret;

                asd = v4l2_async_belongs(notifier, sd);
                if (!asd)
                        continue;

                ret = v4l2_async_test_notify(notifier, sd, asd);
                if (ret < 0) {
                        mutex_unlock(&list_lock);
                        return ret;
                }
        }

        mutex_unlock(&list_lock);

        return 0;
}
EXPORT_SYMBOL(v4l2_async_notifier_register);

void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
{
        struct v4l2_subdev *sd, *tmp;
        unsigned int notif_n_subdev = notifier->num_subdevs;
        unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
        struct device **dev;
        int i = 0;

        if (!notifier->v4l2_dev)
                return;

        dev = kmalloc(n_subdev * sizeof(*dev), GFP_KERNEL);
        if (!dev) {
                dev_err(notifier->v4l2_dev->dev,
                        "Failed to allocate device cache!\n");
        }

        mutex_lock(&list_lock);

        list_del(&notifier->list);

        list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
                struct device *d;

                d = get_device(sd->dev);

                v4l2_async_cleanup(sd);

                /* If we handled USB devices, we'd have to lock the parent too */
                device_release_driver(d);

                if (notifier->unbind)
                        notifier->unbind(notifier, sd, sd->asd);

                /*
                 * Store device at the device cache, in order to call
                 * put_device() on the final step
                 */
                if (dev)
                        dev[i++] = d;
                else
                        put_device(d);
        }

        mutex_unlock(&list_lock);

        /*
         * Call device_attach() to reprobe devices
         *
         * NOTE: If dev allocation fails, i is 0, and the whole loop won't be
         * executed.
         */
        while (i--) {
                struct device *d = dev[i];

                if (d && device_attach(d) < 0) {
                        const char *name = "(none)";
                        int lock = device_trylock(d);

                        if (lock && d->driver)
                                name = d->driver->name;
                        dev_err(d, "Failed to re-probe to %s\n", name);
                        if (lock)
                                device_unlock(d);
                }
                put_device(d);
        }
        kfree(dev);

        notifier->v4l2_dev = NULL;

        /*
         * Don't care about the waiting list, it is initialised and populated
         * upon notifier registration.
         */
}
EXPORT_SYMBOL(v4l2_async_notifier_unregister);

int v4l2_async_register_subdev(struct v4l2_subdev *sd)
{
        struct v4l2_async_notifier *notifier;

        /*
         * No reference taken. The reference is held by the device
         * (struct v4l2_subdev.dev), and async sub-device does not
         * exist independently of the device at any point of time.
         */
        if (!sd->of_node && sd->dev)
                sd->of_node = sd->dev->of_node;

        mutex_lock(&list_lock);

        INIT_LIST_HEAD(&sd->async_list);

        list_for_each_entry(notifier, &notifier_list, list) {
                struct v4l2_async_subdev *asd = v4l2_async_belongs(notifier, sd);
                if (asd) {
                        int ret = v4l2_async_test_notify(notifier, sd, asd);
                        mutex_unlock(&list_lock);
                        return ret;
                }
        }

        /* None matched, wait for hot-plugging */
        list_add(&sd->async_list, &subdev_list);

        mutex_unlock(&list_lock);

        return 0;
}
EXPORT_SYMBOL(v4l2_async_register_subdev);

void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
{
        struct v4l2_async_notifier *notifier = sd->notifier;

        if (!sd->asd) {
                if (!list_empty(&sd->async_list))
                        v4l2_async_cleanup(sd);
                return;
        }

        mutex_lock(&list_lock);

        list_add(&sd->asd->list, &notifier->waiting);

        v4l2_async_cleanup(sd);

        if (notifier->unbind)
                notifier->unbind(notifier, sd, sd->asd);

        mutex_unlock(&list_lock);
}
EXPORT_SYMBOL(v4l2_async_unregister_subdev);