// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Avionic Design GmbH
 * Copyright (C) 2012-2013, NVIDIA Corporation
 */

#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/host1x.h>
#include <linux/of.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/of_device.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
 * @device: host1x device to add the subdevice to
 * @driver: host1x driver containing the subdevices
 * @np: device node
 */
static int host1x_subdev_add(struct host1x_device *device,
                             struct host1x_driver *driver,
                             struct device_node *np)
{
        struct host1x_subdev *subdev;
        int err;

        subdev = kzalloc_obj(*subdev);
        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);

        /* recursively add children */
        for_each_child_of_node_scoped(np, child) {
                if (of_match_node(driver->subdevs, child) &&
                    of_device_is_available(child)) {
                        err = host1x_subdev_add(device, driver, child);
                        if (err < 0) {
                                /* XXX cleanup? */
                                return err;
                        }
                }
        }

        return 0;
}

/**
 * host1x_subdev_del() - remove subdevice
 * @subdev: subdevice to remove
 */
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
 * @device: host1x logical device
 * @driver: host1x driver
 */
static int host1x_device_parse_dt(struct host1x_device *device,
                                  struct host1x_driver *driver)
{
        int err;

        for_each_child_of_node_scoped(device->dev.parent->of_node, np) {
                if (of_match_node(driver->subdevs, np) &&
                    of_device_is_available(np)) {
                        err = host1x_subdev_add(device, driver, 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->host = &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->host = 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);
}

/**
 * host1x_device_init() - initialize a host1x logical device
 * @device: host1x logical device
 *
 * The driver for the host1x logical device can call this during execution of
 * its &host1x_driver.probe implementation to initialize each of its clients.
 * The client drivers access the subsystem specific driver data using the
 * &host1x_client.parent field and driver data associated with it (usually by
 * calling dev_get_drvdata()).
 */
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->early_init) {
                        err = client->ops->early_init(client);
                        if (err < 0) {
                                dev_err(&device->dev, "failed to early initialize %s: %d\n",
                                        dev_name(client->dev), err);
                                goto teardown_late;
                        }
                }
        }

        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);
                                goto teardown;
                        }
                }
        }

        mutex_unlock(&device->clients_lock);

        return 0;

teardown:
        list_for_each_entry_continue_reverse(client, &device->clients, list)
                if (client->ops->exit)
                        client->ops->exit(client);

        /* reset client to end of list for late teardown */
        client = list_entry(&device->clients, struct host1x_client, list);

teardown_late:
        list_for_each_entry_continue_reverse(client, &device->clients, list)
                if (client->ops->late_exit)
                        client->ops->late_exit(client);

        mutex_unlock(&device->clients_lock);
        return err;
}
EXPORT_SYMBOL(host1x_device_init);

/**
 * host1x_device_exit() - uninitialize host1x logical device
 * @device: host1x logical device
 *
 * When the driver for a host1x logical device is unloaded, it can call this
 * function to tear down each of its clients. Typically this is done after a
 * subsystem-specific data structure is removed and the functionality can no
 * longer be used.
 */
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;
                        }
                }
        }

        list_for_each_entry_reverse(client, &device->clients, list) {
                if (client->ops && client->ops->late_exit) {
                        err = client->ops->late_exit(client);
                        if (err < 0) {
                                dev_err(&device->dev, "failed to late 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, const struct device_driver *drv)
{
        return strcmp(dev_name(dev), drv->name) == 0;
}

/*
 * Note that this is really only needed for backwards compatibility
 * with libdrm, which parses this information from sysfs and will
 * fail if it can't find the OF_FULLNAME, specifically.
 */
static int host1x_device_uevent(const struct device *dev,
                                struct kobj_uevent_env *env)
{
        of_device_uevent(dev->parent, env);

        return 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 void 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)
                driver->remove(device);
}

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 (dev->driver && 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,
};

const struct bus_type host1x_bus_type = {
        .name = "host1x",
        .match = host1x_device_match,
        .uevent = host1x_device_uevent,
        .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_obj(*device);
        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;

        device->dev.dma_parms = &device->dma_parms;
        dma_set_max_seg_size(&device->dev, UINT_MAX);

        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);

        /*
         * Add device even if there are no subdevs to ensure syncpoint functionality
         * is available regardless of whether any engine subdevices are present
         */
        if (list_empty(&device->subdevs)) {
                err = device_add(&device->dev);
                if (err < 0)
                        dev_err(&device->dev, "failed to add device: %d\n", err);
                else
                        device->registered = true;
        }

        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);
}

static int host1x_devices_show(struct seq_file *s, void *data)
{
        struct host1x *host1x = s->private;
        struct host1x_device *device;

        mutex_lock(&host1x->devices_lock);

        list_for_each_entry(device, &host1x->devices, list) {
                struct host1x_subdev *subdev;

                seq_printf(s, "%s\n", dev_name(&device->dev));

                mutex_lock(&device->subdevs_lock);

                list_for_each_entry(subdev, &device->active, list)
                        seq_printf(s, "  %pOFf: %s\n", subdev->np,
                                   dev_name(subdev->client->dev));

                list_for_each_entry(subdev, &device->subdevs, list)
                        seq_printf(s, "  %pOFf:\n", subdev->np);

                mutex_unlock(&device->subdevs_lock);
        }

        mutex_unlock(&host1x->devices_lock);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(host1x_devices);

/**
 * host1x_register() - register a host1x controller
 * @host1x: host1x controller
 *
 * The host1x controller driver uses this to register a host1x controller with
 * the infrastructure. Note that all Tegra SoC generations have only ever come
 * with a single host1x instance, so this function is somewhat academic.
 */
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);

        debugfs_create_file("devices", S_IRUGO, host1x->debugfs, host1x,
                            &host1x_devices_fops);

        return 0;
}

/**
 * host1x_unregister() - unregister a host1x controller
 * @host1x: host1x controller
 *
 * The host1x controller driver uses this to remove a host1x controller from
 * the infrastructure.
 */
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;
}

/**
 * host1x_driver_register_full() - register a host1x driver
 * @driver: host1x driver
 * @owner: owner module
 *
 * Drivers for host1x logical devices call this function to register a driver
 * with the infrastructure. Note that since these drive logical devices, the
 * registration of the driver actually triggers tho logical device creation.
 * A logical device will be created for each host1x instance.
 */
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);

/**
 * host1x_driver_unregister() - unregister a host1x driver
 * @driver: host1x driver
 *
 * Unbinds the driver from each of the host1x logical devices that it is
 * bound to, effectively removing the subsystem devices that they represent.
 */
void host1x_driver_unregister(struct host1x_driver *driver)
{
        struct host1x *host1x;

        driver_unregister(&driver->driver);

        mutex_lock(&devices_lock);

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

        mutex_unlock(&devices_lock);

        mutex_lock(&drivers_lock);
        list_del_init(&driver->list);
        mutex_unlock(&drivers_lock);
}
EXPORT_SYMBOL(host1x_driver_unregister);

/**
 * __host1x_client_init() - initialize a host1x client
 * @client: host1x client
 * @key: lock class key for the client-specific mutex
 */
void __host1x_client_init(struct host1x_client *client, struct lock_class_key *key)
{
        host1x_bo_cache_init(&client->cache);
        INIT_LIST_HEAD(&client->list);
        __mutex_init(&client->lock, "host1x client lock", key);
        client->usecount = 0;
}
EXPORT_SYMBOL(__host1x_client_init);

/**
 * host1x_client_exit() - uninitialize a host1x client
 * @client: host1x client
 */
void host1x_client_exit(struct host1x_client *client)
{
        mutex_destroy(&client->lock);
}
EXPORT_SYMBOL(host1x_client_exit);

/**
 * __host1x_client_register() - register a host1x client
 * @client: host1x client
 *
 * Registers a host1x client with each host1x controller instance. Note that
 * each client will only match their parent host1x controller and will only be
 * associated with that instance. Once all clients have been registered with
 * their parent host1x controller, the infrastructure will set up the logical
 * device and call host1x_device_init(), which will in turn call each client's
 * &host1x_client_ops.init implementation.
 */
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);

/**
 * host1x_client_unregister() - unregister a host1x client
 * @client: host1x client
 *
 * Removes a host1x client from its host1x controller instance. If a logical
 * device has already been initialized, it will be torn down.
 */
void 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;
                }
        }

        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);

        host1x_bo_cache_destroy(&client->cache);
}
EXPORT_SYMBOL(host1x_client_unregister);

int host1x_client_suspend(struct host1x_client *client)
{
        int err = 0;

        mutex_lock(&client->lock);

        if (client->usecount == 1) {
                if (client->ops && client->ops->suspend) {
                        err = client->ops->suspend(client);
                        if (err < 0)
                                goto unlock;
                }
        }

        client->usecount--;
        dev_dbg(client->dev, "use count: %u\n", client->usecount);

        if (client->parent) {
                err = host1x_client_suspend(client->parent);
                if (err < 0)
                        goto resume;
        }

        goto unlock;

resume:
        if (client->usecount == 0)
                if (client->ops && client->ops->resume)
                        client->ops->resume(client);

        client->usecount++;
unlock:
        mutex_unlock(&client->lock);
        return err;
}
EXPORT_SYMBOL(host1x_client_suspend);

int host1x_client_resume(struct host1x_client *client)
{
        int err = 0;

        mutex_lock(&client->lock);

        if (client->parent) {
                err = host1x_client_resume(client->parent);
                if (err < 0)
                        goto unlock;
        }

        if (client->usecount == 0) {
                if (client->ops && client->ops->resume) {
                        err = client->ops->resume(client);
                        if (err < 0)
                                goto suspend;
                }
        }

        client->usecount++;
        dev_dbg(client->dev, "use count: %u\n", client->usecount);

        goto unlock;

suspend:
        if (client->parent)
                host1x_client_suspend(client->parent);
unlock:
        mutex_unlock(&client->lock);
        return err;
}
EXPORT_SYMBOL(host1x_client_resume);

struct host1x_bo_mapping *host1x_bo_pin(struct device *dev, struct host1x_bo *bo,
                                        enum dma_data_direction dir,
                                        struct host1x_bo_cache *cache)
{
        struct host1x_bo_mapping *mapping;

        if (cache) {
                mutex_lock(&cache->lock);

                list_for_each_entry(mapping, &cache->mappings, entry) {
                        if (mapping->bo == bo && mapping->direction == dir) {
                                kref_get(&mapping->ref);
                                goto unlock;
                        }
                }
        }

        mapping = bo->ops->pin(dev, bo, dir);
        if (IS_ERR(mapping))
                goto unlock;

        spin_lock(&mapping->bo->lock);
        list_add_tail(&mapping->list, &bo->mappings);
        spin_unlock(&mapping->bo->lock);

        if (cache) {
                INIT_LIST_HEAD(&mapping->entry);
                mapping->cache = cache;

                list_add_tail(&mapping->entry, &cache->mappings);

                /* bump reference count to track the copy in the cache */
                kref_get(&mapping->ref);
        }

unlock:
        if (cache)
                mutex_unlock(&cache->lock);

        return mapping;
}
EXPORT_SYMBOL(host1x_bo_pin);

static void __host1x_bo_unpin(struct kref *ref)
{
        struct host1x_bo_mapping *mapping = to_host1x_bo_mapping(ref);

        /*
         * When the last reference of the mapping goes away, make sure to remove the mapping from
         * the cache.
         */
        if (mapping->cache)
                list_del(&mapping->entry);

        spin_lock(&mapping->bo->lock);
        list_del(&mapping->list);
        spin_unlock(&mapping->bo->lock);

        mapping->bo->ops->unpin(mapping);
}

void host1x_bo_unpin(struct host1x_bo_mapping *mapping)
{
        struct host1x_bo_cache *cache = mapping->cache;

        if (cache)
                mutex_lock(&cache->lock);

        kref_put(&mapping->ref, __host1x_bo_unpin);

        if (cache)
                mutex_unlock(&cache->lock);
}
EXPORT_SYMBOL(host1x_bo_unpin);