/*
 * Copyright (C) 2012 Avionic Design GmbH
 * Copyright (C) 2012-2013, NVIDIA Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/host1x.h>
#include <linux/of.h>
#include <linux/slab.h>

#include "bus.h"
#include "dev.h"

static DEFINE_MUTEX(clients_lock);
static LIST_HEAD(clients);

static DEFINE_MUTEX(drivers_lock);
static LIST_HEAD(drivers);

static DEFINE_MUTEX(devices_lock);
static LIST_HEAD(devices);

struct host1x_subdev {
        struct host1x_client *client;
        struct device_node *np;
        struct list_head list;
};

/**
 * host1x_subdev_add() - add a new subdevice with an associated device node
 */
static int host1x_subdev_add(struct host1x_device *device,
                             struct device_node *np)
{
        struct host1x_subdev *subdev;

        subdev = kzalloc(sizeof(*subdev), GFP_KERNEL);
        if (!subdev)
                return -ENOMEM;

        INIT_LIST_HEAD(&subdev->list);
        subdev->np = of_node_get(np);

        mutex_lock(&device->subdevs_lock);
        list_add_tail(&subdev->list, &device->subdevs);
        mutex_unlock(&device->subdevs_lock);

        return 0;
}

/**
 * host1x_subdev_del() - remove subdevice
 */
static void host1x_subdev_del(struct host1x_subdev *subdev)
{
        list_del(&subdev->list);
        of_node_put(subdev->np);
        kfree(subdev);
}

/**
 * host1x_device_parse_dt() - scan device tree and add matching subdevices
 */
static int host1x_device_parse_dt(struct host1x_device *device,
                                  struct host1x_driver *driver)
{
        struct device_node *np;
        int err;

        for_each_child_of_node(device->dev.parent->of_node, np) {
                if (of_match_node(driver->subdevs, np) &&
                    of_device_is_available(np)) {
                        err = host1x_subdev_add(device, np);
                        if (err < 0)
                                return err;
                }
        }

        return 0;
}

static void host1x_subdev_register(struct host1x_device *device,
                                   struct host1x_subdev *subdev,
                                   struct host1x_client *client)
{
        int err;

        /*
         * Move the subdevice to the list of active (registered) subdevices
         * and associate it with a client. At the same time, associate the
         * client with its parent device.
         */
        mutex_lock(&device->subdevs_lock);
        mutex_lock(&device->clients_lock);
        list_move_tail(&client->list, &device->clients);
        list_move_tail(&subdev->list, &device->active);
        client->parent = &device->dev;
        subdev->client = client;
        mutex_unlock(&device->clients_lock);
        mutex_unlock(&device->subdevs_lock);

        if (list_empty(&device->subdevs)) {
                err = device_add(&device->dev);
                if (err < 0)
                        dev_err(&device->dev, "failed to add: %d\n", err);
                else
                        device->registered = true;
        }
}

static void __host1x_subdev_unregister(struct host1x_device *device,
                                       struct host1x_subdev *subdev)
{
        struct host1x_client *client = subdev->client;

        /*
         * If all subdevices have been activated, we're about to remove the
         * first active subdevice, so unload the driver first.
         */
        if (list_empty(&device->subdevs)) {
                if (device->registered) {
                        device->registered = false;
                        device_del(&device->dev);
                }
        }

        /*
         * Move the subdevice back to the list of idle subdevices and remove
         * it from list of clients.
         */
        mutex_lock(&device->clients_lock);
        subdev->client = NULL;
        client->parent = NULL;
        list_move_tail(&subdev->list, &device->subdevs);
        /*
         * XXX: Perhaps don't do this here, but rather explicitly remove it
         * when the device is about to be deleted.
         *
         * This is somewhat complicated by the fact that this function is
         * used to remove the subdevice when a client is unregistered but
         * also when the composite device is about to be removed.
         */
        list_del_init(&client->list);
        mutex_unlock(&device->clients_lock);
}

static void host1x_subdev_unregister(struct host1x_device *device,
                                     struct host1x_subdev *subdev)
{
        mutex_lock(&device->subdevs_lock);
        __host1x_subdev_unregister(device, subdev);
        mutex_unlock(&device->subdevs_lock);
}

int host1x_device_init(struct host1x_device *device)
{
        struct host1x_client *client;
        int err;

        mutex_lock(&device->clients_lock);

        list_for_each_entry(client, &device->clients, list) {
                if (client->ops && client->ops->init) {
                        err = client->ops->init(client);
                        if (err < 0) {
                                dev_err(&device->dev,
                                        "failed to initialize %s: %d\n",
                                        dev_name(client->dev), err);
                                mutex_unlock(&device->clients_lock);
                                return err;
                        }
                }
        }

        mutex_unlock(&device->clients_lock);

        return 0;
}
EXPORT_SYMBOL(host1x_device_init);

int host1x_device_exit(struct host1x_device *device)
{
        struct host1x_client *client;
        int err;

        mutex_lock(&device->clients_lock);

        list_for_each_entry_reverse(client, &device->clients, list) {
                if (client->ops && client->ops->exit) {
                        err = client->ops->exit(client);
                        if (err < 0) {
                                dev_err(&device->dev,
                                        "failed to cleanup %s: %d\n",
                                        dev_name(client->dev), err);
                                mutex_unlock(&device->clients_lock);
                                return err;
                        }
                }
        }

        mutex_unlock(&device->clients_lock);

        return 0;
}
EXPORT_SYMBOL(host1x_device_exit);

static int host1x_add_client(struct host1x *host1x,
                             struct host1x_client *client)
{
        struct host1x_device *device;
        struct host1x_subdev *subdev;

        mutex_lock(&host1x->devices_lock);

        list_for_each_entry(device, &host1x->devices, list) {
                list_for_each_entry(subdev, &device->subdevs, list) {
                        if (subdev->np == client->dev->of_node) {
                                host1x_subdev_register(device, subdev, client);
                                mutex_unlock(&host1x->devices_lock);
                                return 0;
                        }
                }
        }

        mutex_unlock(&host1x->devices_lock);
        return -ENODEV;
}

static int host1x_del_client(struct host1x *host1x,
                             struct host1x_client *client)
{
        struct host1x_device *device, *dt;
        struct host1x_subdev *subdev;

        mutex_lock(&host1x->devices_lock);

        list_for_each_entry_safe(device, dt, &host1x->devices, list) {
                list_for_each_entry(subdev, &device->active, list) {
                        if (subdev->client == client) {
                                host1x_subdev_unregister(device, subdev);
                                mutex_unlock(&host1x->devices_lock);
                                return 0;
                        }
                }
        }

        mutex_unlock(&host1x->devices_lock);
        return -ENODEV;
}

static int host1x_device_match(struct device *dev, struct device_driver *drv)
{
        return strcmp(dev_name(dev), drv->name) == 0;
}

static int host1x_device_probe(struct device *dev)
{
        struct host1x_driver *driver = to_host1x_driver(dev->driver);
        struct host1x_device *device = to_host1x_device(dev);

        if (driver->probe)
                return driver->probe(device);

        return 0;
}

static int host1x_device_remove(struct device *dev)
{
        struct host1x_driver *driver = to_host1x_driver(dev->driver);
        struct host1x_device *device = to_host1x_device(dev);

        if (driver->remove)
                return driver->remove(device);

        return 0;
}

static void host1x_device_shutdown(struct device *dev)
{
        struct host1x_driver *driver = to_host1x_driver(dev->driver);
        struct host1x_device *device = to_host1x_device(dev);

        if (driver->shutdown)
                driver->shutdown(device);
}

static const struct dev_pm_ops host1x_device_pm_ops = {
        .suspend = pm_generic_suspend,
        .resume = pm_generic_resume,
        .freeze = pm_generic_freeze,
        .thaw = pm_generic_thaw,
        .poweroff = pm_generic_poweroff,
        .restore = pm_generic_restore,
};

struct bus_type host1x_bus_type = {
        .name = "host1x",
        .match = host1x_device_match,
        .probe = host1x_device_probe,
        .remove = host1x_device_remove,
        .shutdown = host1x_device_shutdown,
        .pm = &host1x_device_pm_ops,
};

static void __host1x_device_del(struct host1x_device *device)
{
        struct host1x_subdev *subdev, *sd;
        struct host1x_client *client, *cl;

        mutex_lock(&device->subdevs_lock);

        /* unregister subdevices */
        list_for_each_entry_safe(subdev, sd, &device->active, list) {
                /*
                 * host1x_subdev_unregister() will remove the client from
                 * any lists, so we'll need to manually add it back to the
                 * list of idle clients.
                 *
                 * XXX: Alternatively, perhaps don't remove the client from
                 * any lists in host1x_subdev_unregister() and instead do
                 * that explicitly from host1x_unregister_client()?
                 */
                client = subdev->client;

                __host1x_subdev_unregister(device, subdev);

                /* add the client to the list of idle clients */
                mutex_lock(&clients_lock);
                list_add_tail(&client->list, &clients);
                mutex_unlock(&clients_lock);
        }

        /* remove subdevices */
        list_for_each_entry_safe(subdev, sd, &device->subdevs, list)
                host1x_subdev_del(subdev);

        mutex_unlock(&device->subdevs_lock);

        /* move clients to idle list */
        mutex_lock(&clients_lock);
        mutex_lock(&device->clients_lock);

        list_for_each_entry_safe(client, cl, &device->clients, list)
                list_move_tail(&client->list, &clients);

        mutex_unlock(&device->clients_lock);
        mutex_unlock(&clients_lock);

        /* finally remove the device */
        list_del_init(&device->list);
}

static void host1x_device_release(struct device *dev)
{
        struct host1x_device *device = to_host1x_device(dev);

        __host1x_device_del(device);
        kfree(device);
}

static int host1x_device_add(struct host1x *host1x,
                             struct host1x_driver *driver)
{
        struct host1x_client *client, *tmp;
        struct host1x_subdev *subdev;
        struct host1x_device *device;
        int err;

        device = kzalloc(sizeof(*device), GFP_KERNEL);
        if (!device)
                return -ENOMEM;

        device_initialize(&device->dev);

        mutex_init(&device->subdevs_lock);
        INIT_LIST_HEAD(&device->subdevs);
        INIT_LIST_HEAD(&device->active);
        mutex_init(&device->clients_lock);
        INIT_LIST_HEAD(&device->clients);
        INIT_LIST_HEAD(&device->list);
        device->driver = driver;

        device->dev.coherent_dma_mask = host1x->dev->coherent_dma_mask;
        device->dev.dma_mask = &device->dev.coherent_dma_mask;
        dev_set_name(&device->dev, "%s", driver->driver.name);
        device->dev.release = host1x_device_release;
        device->dev.bus = &host1x_bus_type;
        device->dev.parent = host1x->dev;

        err = host1x_device_parse_dt(device, driver);
        if (err < 0) {
                kfree(device);
                return err;
        }

        list_add_tail(&device->list, &host1x->devices);

        mutex_lock(&clients_lock);

        list_for_each_entry_safe(client, tmp, &clients, list) {
                list_for_each_entry(subdev, &device->subdevs, list) {
                        if (subdev->np == client->dev->of_node) {
                                host1x_subdev_register(device, subdev, client);
                                break;
                        }
                }
        }

        mutex_unlock(&clients_lock);

        return 0;
}

/*
 * Removes a device by first unregistering any subdevices and then removing
 * itself from the list of devices.
 *
 * This function must be called with the host1x->devices_lock held.
 */
static void host1x_device_del(struct host1x *host1x,
                              struct host1x_device *device)
{
        if (device->registered) {
                device->registered = false;
                device_del(&device->dev);
        }

        put_device(&device->dev);
}

static void host1x_attach_driver(struct host1x *host1x,
                                 struct host1x_driver *driver)
{
        struct host1x_device *device;
        int err;

        mutex_lock(&host1x->devices_lock);

        list_for_each_entry(device, &host1x->devices, list) {
                if (device->driver == driver) {
                        mutex_unlock(&host1x->devices_lock);
                        return;
                }
        }

        err = host1x_device_add(host1x, driver);
        if (err < 0)
                dev_err(host1x->dev, "failed to allocate device: %d\n", err);

        mutex_unlock(&host1x->devices_lock);
}

static void host1x_detach_driver(struct host1x *host1x,
                                 struct host1x_driver *driver)
{
        struct host1x_device *device, *tmp;

        mutex_lock(&host1x->devices_lock);

        list_for_each_entry_safe(device, tmp, &host1x->devices, list)
                if (device->driver == driver)
                        host1x_device_del(host1x, device);

        mutex_unlock(&host1x->devices_lock);
}

int host1x_register(struct host1x *host1x)
{
        struct host1x_driver *driver;

        mutex_lock(&devices_lock);
        list_add_tail(&host1x->list, &devices);
        mutex_unlock(&devices_lock);

        mutex_lock(&drivers_lock);

        list_for_each_entry(driver, &drivers, list)
                host1x_attach_driver(host1x, driver);

        mutex_unlock(&drivers_lock);

        return 0;
}

int host1x_unregister(struct host1x *host1x)
{
        struct host1x_driver *driver;

        mutex_lock(&drivers_lock);

        list_for_each_entry(driver, &drivers, list)
                host1x_detach_driver(host1x, driver);

        mutex_unlock(&drivers_lock);

        mutex_lock(&devices_lock);
        list_del_init(&host1x->list);
        mutex_unlock(&devices_lock);

        return 0;
}

int host1x_driver_register_full(struct host1x_driver *driver,
                                struct module *owner)
{
        struct host1x *host1x;

        INIT_LIST_HEAD(&driver->list);

        mutex_lock(&drivers_lock);
        list_add_tail(&driver->list, &drivers);
        mutex_unlock(&drivers_lock);

        mutex_lock(&devices_lock);

        list_for_each_entry(host1x, &devices, list)
                host1x_attach_driver(host1x, driver);

        mutex_unlock(&devices_lock);

        driver->driver.bus = &host1x_bus_type;
        driver->driver.owner = owner;

        return driver_register(&driver->driver);
}
EXPORT_SYMBOL(host1x_driver_register_full);

void host1x_driver_unregister(struct host1x_driver *driver)
{
        mutex_lock(&drivers_lock);
        list_del_init(&driver->list);
        mutex_unlock(&drivers_lock);
}
EXPORT_SYMBOL(host1x_driver_unregister);

int host1x_client_register(struct host1x_client *client)
{
        struct host1x *host1x;
        int err;

        mutex_lock(&devices_lock);

        list_for_each_entry(host1x, &devices, list) {
                err = host1x_add_client(host1x, client);
                if (!err) {
                        mutex_unlock(&devices_lock);
                        return 0;
                }
        }

        mutex_unlock(&devices_lock);

        mutex_lock(&clients_lock);
        list_add_tail(&client->list, &clients);
        mutex_unlock(&clients_lock);

        return 0;
}
EXPORT_SYMBOL(host1x_client_register);

int host1x_client_unregister(struct host1x_client *client)
{
        struct host1x_client *c;
        struct host1x *host1x;
        int err;

        mutex_lock(&devices_lock);

        list_for_each_entry(host1x, &devices, list) {
                err = host1x_del_client(host1x, client);
                if (!err) {
                        mutex_unlock(&devices_lock);
                        return 0;
                }
        }

        mutex_unlock(&devices_lock);
        mutex_lock(&clients_lock);

        list_for_each_entry(c, &clients, list) {
                if (c == client) {
                        list_del_init(&c->list);
                        break;
                }
        }

        mutex_unlock(&clients_lock);

        return 0;
}
EXPORT_SYMBOL(host1x_client_unregister);