// SPDX-License-Identifier: GPL-2.0
/*
 * Componentized device handling.
 */
#include <linux/component.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/debugfs.h>

/**
 * DOC: overview
 *
 * The component helper allows drivers to collect a pile of sub-devices,
 * including their bound drivers, into an aggregate driver. Various subsystems
 * already provide functions to get hold of such components, e.g.
 * of_clk_get_by_name(). The component helper can be used when such a
 * subsystem-specific way to find a device is not available: The component
 * helper fills the niche of aggregate drivers for specific hardware, where
 * further standardization into a subsystem would not be practical. The common
 * example is when a logical device (e.g. a DRM display driver) is spread around
 * the SoC on various components (scanout engines, blending blocks, transcoders
 * for various outputs and so on).
 *
 * The component helper also doesn't solve runtime dependencies, e.g. for system
 * suspend and resume operations. See also :ref:`device links<device_link>`.
 *
 * Components are registered using component_add() and unregistered with
 * component_del(), usually from the driver's probe and disconnect functions.
 *
 * Aggregate drivers first assemble a component match list of what they need
 * using component_match_add(). This is then registered as an aggregate driver
 * using component_master_add_with_match(), and unregistered using
 * component_master_del().
 */

struct component;

struct component_match_array {
        void *data;
        int (*compare)(struct device *, void *);
        int (*compare_typed)(struct device *, int, void *);
        void (*release)(struct device *, void *);
        struct component *component;
        bool duplicate;
};

struct component_match {
        size_t alloc;
        size_t num;
        struct component_match_array *compare;
};

struct aggregate_device {
        struct list_head node;
        bool bound;

        const struct component_master_ops *ops;
        struct device *parent;
        struct component_match *match;
};

struct component {
        struct list_head node;
        struct aggregate_device *adev;
        bool bound;

        const struct component_ops *ops;
        int subcomponent;
        struct device *dev;
};

static DEFINE_MUTEX(component_mutex);
static LIST_HEAD(component_list);
static LIST_HEAD(aggregate_devices);

#ifdef CONFIG_DEBUG_FS

static struct dentry *component_debugfs_dir;

static int component_devices_show(struct seq_file *s, void *data)
{
        struct aggregate_device *m = s->private;
        struct component_match *match = m->match;
        size_t i;

        mutex_lock(&component_mutex);
        seq_printf(s, "%-50s %20s\n", "aggregate_device name", "status");
        seq_puts(s, "-----------------------------------------------------------------------\n");
        seq_printf(s, "%-50s %20s\n\n",
                   dev_name(m->parent), m->bound ? "bound" : "not bound");

        seq_printf(s, "%-50s %20s\n", "device name", "status");
        seq_puts(s, "-----------------------------------------------------------------------\n");
        for (i = 0; i < match->num; i++) {
                struct component *component = match->compare[i].component;

                seq_printf(s, "%-50s %20s\n",
                           component ? dev_name(component->dev) : "(unknown)",
                           component ? (component->bound ? "bound" : "not bound") : "not registered");
        }
        mutex_unlock(&component_mutex);

        return 0;
}

DEFINE_SHOW_ATTRIBUTE(component_devices);

static int __init component_debug_init(void)
{
        component_debugfs_dir = debugfs_create_dir("device_component", NULL);

        return 0;
}

core_initcall(component_debug_init);

static void component_debugfs_add(struct aggregate_device *m)
{
        debugfs_create_file(dev_name(m->parent), 0444, component_debugfs_dir, m,
                            &component_devices_fops);
}

static void component_debugfs_del(struct aggregate_device *m)
{
        debugfs_lookup_and_remove(dev_name(m->parent), component_debugfs_dir);
}

#else

static void component_debugfs_add(struct aggregate_device *m)
{ }

static void component_debugfs_del(struct aggregate_device *m)
{ }

#endif

static struct aggregate_device *__aggregate_find(struct device *parent,
        const struct component_master_ops *ops)
{
        struct aggregate_device *m;

        list_for_each_entry(m, &aggregate_devices, node)
                if (m->parent == parent && (!ops || m->ops == ops))
                        return m;

        return NULL;
}

static struct component *find_component(struct aggregate_device *adev,
        struct component_match_array *mc)
{
        struct component *c;

        list_for_each_entry(c, &component_list, node) {
                if (c->adev && c->adev != adev)
                        continue;

                if (mc->compare && mc->compare(c->dev, mc->data))
                        return c;

                if (mc->compare_typed &&
                    mc->compare_typed(c->dev, c->subcomponent, mc->data))
                        return c;
        }

        return NULL;
}

static int find_components(struct aggregate_device *adev)
{
        struct component_match *match = adev->match;
        size_t i;
        int ret = 0;

        /*
         * Scan the array of match functions and attach
         * any components which are found to this adev.
         */
        for (i = 0; i < match->num; i++) {
                struct component_match_array *mc = &match->compare[i];
                struct component *c;

                dev_dbg(adev->parent, "Looking for component %zu\n", i);

                if (match->compare[i].component)
                        continue;

                c = find_component(adev, mc);
                if (!c) {
                        ret = -ENXIO;
                        break;
                }

                dev_dbg(adev->parent, "found component %s, duplicate %u\n",
                        dev_name(c->dev), !!c->adev);

                /* Attach this component to the adev */
                match->compare[i].duplicate = !!c->adev;
                match->compare[i].component = c;
                c->adev = adev;
        }
        return ret;
}

/* Detach component from associated aggregate_device */
static void remove_component(struct aggregate_device *adev, struct component *c)
{
        size_t i;

        /* Detach the component from this adev. */
        for (i = 0; i < adev->match->num; i++)
                if (adev->match->compare[i].component == c)
                        adev->match->compare[i].component = NULL;
}

/*
 * Try to bring up an aggregate device.  If component is NULL, we're interested
 * in this aggregate device, otherwise it's a component which must be present
 * to try and bring up the aggregate device.
 *
 * Returns 1 for successful bringup, 0 if not ready, or -ve errno.
 */
static int try_to_bring_up_aggregate_device(struct aggregate_device *adev,
        struct component *component)
{
        int ret;

        dev_dbg(adev->parent, "trying to bring up adev\n");

        if (find_components(adev)) {
                dev_dbg(adev->parent, "master has incomplete components\n");
                return 0;
        }

        if (component && component->adev != adev) {
                dev_dbg(adev->parent, "master is not for this component (%s)\n",
                        dev_name(component->dev));
                return 0;
        }

        if (!devres_open_group(adev->parent, adev, GFP_KERNEL))
                return -ENOMEM;

        /* Found all components */
        ret = adev->ops->bind(adev->parent);
        if (ret < 0) {
                devres_release_group(adev->parent, NULL);
                if (ret != -EPROBE_DEFER)
                        dev_info(adev->parent, "adev bind failed: %d\n", ret);
                return ret;
        }

        devres_close_group(adev->parent, NULL);
        adev->bound = true;
        return 1;
}

static int try_to_bring_up_masters(struct component *component)
{
        struct aggregate_device *adev;
        int ret = 0;

        list_for_each_entry(adev, &aggregate_devices, node) {
                if (!adev->bound) {
                        ret = try_to_bring_up_aggregate_device(adev, component);
                        if (ret != 0)
                                break;
                }
        }

        return ret;
}

static void take_down_aggregate_device(struct aggregate_device *adev)
{
        if (adev->bound) {
                adev->ops->unbind(adev->parent);
                devres_release_group(adev->parent, adev);
                adev->bound = false;
        }
}

/**
 * component_compare_of - A common component compare function for of_node
 * @dev: component device
 * @data: @compare_data from component_match_add_release()
 *
 * A common compare function when compare_data is device of_node. e.g.
 * component_match_add_release(masterdev, &match, component_release_of,
 * component_compare_of, component_dev_of_node)
 */
int component_compare_of(struct device *dev, void *data)
{
        return device_match_of_node(dev, data);
}
EXPORT_SYMBOL_GPL(component_compare_of);

/**
 * component_release_of - A common component release function for of_node
 * @dev: component device
 * @data: @compare_data from component_match_add_release()
 *
 * About the example, Please see component_compare_of().
 */
void component_release_of(struct device *dev, void *data)
{
        of_node_put(data);
}
EXPORT_SYMBOL_GPL(component_release_of);

/**
 * component_compare_dev - A common component compare function for dev
 * @dev: component device
 * @data: @compare_data from component_match_add_release()
 *
 * A common compare function when compare_data is struce device. e.g.
 * component_match_add(masterdev, &match, component_compare_dev, component_dev)
 */
int component_compare_dev(struct device *dev, void *data)
{
        return dev == data;
}
EXPORT_SYMBOL_GPL(component_compare_dev);

/**
 * component_compare_dev_name - A common component compare function for device name
 * @dev: component device
 * @data: @compare_data from component_match_add_release()
 *
 * A common compare function when compare_data is device name string. e.g.
 * component_match_add(masterdev, &match, component_compare_dev_name,
 * "component_dev_name")
 */
int component_compare_dev_name(struct device *dev, void *data)
{
        return device_match_name(dev, data);
}
EXPORT_SYMBOL_GPL(component_compare_dev_name);

static void devm_component_match_release(struct device *parent, void *res)
{
        struct component_match *match = res;
        unsigned int i;

        for (i = 0; i < match->num; i++) {
                struct component_match_array *mc = &match->compare[i];

                if (mc->release)
                        mc->release(parent, mc->data);
        }

        kfree(match->compare);
}

static int component_match_realloc(struct component_match *match, size_t num)
{
        struct component_match_array *new;

        if (match->alloc == num)
                return 0;

        new = kmalloc_objs(*new, num);
        if (!new)
                return -ENOMEM;

        if (match->compare) {
                memcpy(new, match->compare, sizeof(*new) *
                                            min(match->num, num));
                kfree(match->compare);
        }
        match->compare = new;
        match->alloc = num;

        return 0;
}

static void __component_match_add(struct device *parent,
        struct component_match **matchptr,
        void (*release)(struct device *, void *),
        int (*compare)(struct device *, void *),
        int (*compare_typed)(struct device *, int, void *),
        void *compare_data)
{
        struct component_match *match = *matchptr;

        if (IS_ERR(match))
                return;

        if (!match) {
                match = devres_alloc(devm_component_match_release,
                                     sizeof(*match), GFP_KERNEL);
                if (!match) {
                        *matchptr = ERR_PTR(-ENOMEM);
                        return;
                }

                devres_add(parent, match);

                *matchptr = match;
        }

        if (match->num == match->alloc) {
                size_t new_size = match->alloc + 16;
                int ret;

                ret = component_match_realloc(match, new_size);
                if (ret) {
                        *matchptr = ERR_PTR(ret);
                        return;
                }
        }

        match->compare[match->num].compare = compare;
        match->compare[match->num].compare_typed = compare_typed;
        match->compare[match->num].release = release;
        match->compare[match->num].data = compare_data;
        match->compare[match->num].component = NULL;
        match->num++;
}

/**
 * component_match_add_release - add a component match entry with release callback
 * @parent: parent device of the aggregate driver
 * @matchptr: pointer to the list of component matches
 * @release: release function for @compare_data
 * @compare: compare function to match against all components
 * @compare_data: opaque pointer passed to the @compare function
 *
 * Adds a new component match to the list stored in @matchptr, which the
 * aggregate driver needs to function. The list of component matches pointed to
 * by @matchptr must be initialized to NULL before adding the first match. This
 * only matches against components added with component_add().
 *
 * The allocated match list in @matchptr is automatically released using devm
 * actions, where upon @release will be called to free any references held by
 * @compare_data, e.g. when @compare_data is a &device_node that must be
 * released with of_node_put().
 *
 * See also component_match_add() and component_match_add_typed().
 */
void component_match_add_release(struct device *parent,
        struct component_match **matchptr,
        void (*release)(struct device *, void *),
        int (*compare)(struct device *, void *), void *compare_data)
{
        __component_match_add(parent, matchptr, release, compare, NULL,
                              compare_data);
}
EXPORT_SYMBOL(component_match_add_release);

/**
 * component_match_add_typed - add a component match entry for a typed component
 * @parent: parent device of the aggregate driver
 * @matchptr: pointer to the list of component matches
 * @compare_typed: compare function to match against all typed components
 * @compare_data: opaque pointer passed to the @compare function
 *
 * Adds a new component match to the list stored in @matchptr, which the
 * aggregate driver needs to function. The list of component matches pointed to
 * by @matchptr must be initialized to NULL before adding the first match. This
 * only matches against components added with component_add_typed().
 *
 * The allocated match list in @matchptr is automatically released using devm
 * actions.
 *
 * See also component_match_add_release() and component_match_add_typed().
 */
void component_match_add_typed(struct device *parent,
        struct component_match **matchptr,
        int (*compare_typed)(struct device *, int, void *), void *compare_data)
{
        __component_match_add(parent, matchptr, NULL, NULL, compare_typed,
                              compare_data);
}
EXPORT_SYMBOL(component_match_add_typed);

static void free_aggregate_device(struct aggregate_device *adev)
{
        struct component_match *match = adev->match;
        int i;

        component_debugfs_del(adev);
        list_del(&adev->node);

        if (match) {
                for (i = 0; i < match->num; i++) {
                        struct component *c = match->compare[i].component;
                        if (c)
                                c->adev = NULL;
                }
        }

        kfree(adev);
}

/**
 * component_master_add_with_match - register an aggregate driver
 * @parent: parent device of the aggregate driver
 * @ops: callbacks for the aggregate driver
 * @match: component match list for the aggregate driver
 *
 * Registers a new aggregate driver consisting of the components added to @match
 * by calling one of the component_match_add() functions. Once all components in
 * @match are available, it will be assembled by calling
 * &component_master_ops.bind from @ops. Must be unregistered by calling
 * component_master_del().
 */
int component_master_add_with_match(struct device *parent,
        const struct component_master_ops *ops,
        struct component_match *match)
{
        struct aggregate_device *adev;
        int ret;

        /* Reallocate the match array for its true size */
        ret = component_match_realloc(match, match->num);
        if (ret)
                return ret;

        adev = kzalloc_obj(*adev);
        if (!adev)
                return -ENOMEM;

        adev->parent = parent;
        adev->ops = ops;
        adev->match = match;

        component_debugfs_add(adev);
        /* Add to the list of available aggregate devices. */
        mutex_lock(&component_mutex);
        list_add(&adev->node, &aggregate_devices);

        ret = try_to_bring_up_aggregate_device(adev, NULL);

        if (ret < 0)
                free_aggregate_device(adev);

        mutex_unlock(&component_mutex);

        return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(component_master_add_with_match);

/**
 * component_master_del - unregister an aggregate driver
 * @parent: parent device of the aggregate driver
 * @ops: callbacks for the aggregate driver
 *
 * Unregisters an aggregate driver registered with
 * component_master_add_with_match(). If necessary the aggregate driver is first
 * disassembled by calling &component_master_ops.unbind from @ops.
 */
void component_master_del(struct device *parent,
        const struct component_master_ops *ops)
{
        struct aggregate_device *adev;

        mutex_lock(&component_mutex);
        adev = __aggregate_find(parent, ops);
        if (adev) {
                take_down_aggregate_device(adev);
                free_aggregate_device(adev);
        }
        mutex_unlock(&component_mutex);
}
EXPORT_SYMBOL_GPL(component_master_del);

bool component_master_is_bound(struct device *parent,
        const struct component_master_ops *ops)
{
        struct aggregate_device *adev;

        guard(mutex)(&component_mutex);
        adev = __aggregate_find(parent, ops);
        if (!adev)
                return 0;

        return adev->bound;
}
EXPORT_SYMBOL_GPL(component_master_is_bound);

static void component_unbind(struct component *component,
        struct aggregate_device *adev, void *data)
{
        if (WARN_ON(!component->bound))
                return;

        dev_dbg(adev->parent, "unbinding %s component %p (ops %ps)\n",
                dev_name(component->dev), component, component->ops);

        if (component->ops && component->ops->unbind)
                component->ops->unbind(component->dev, adev->parent, data);
        component->bound = false;

        /* Release all resources claimed in the binding of this component */
        devres_release_group(component->dev, component);
}

/**
 * component_unbind_all - unbind all components of an aggregate driver
 * @parent: parent device of the aggregate driver
 * @data: opaque pointer, passed to all components
 *
 * Unbinds all components of the aggregate device by passing @data to their
 * &component_ops.unbind functions. Should be called from
 * &component_master_ops.unbind.
 */
void component_unbind_all(struct device *parent, void *data)
{
        struct aggregate_device *adev;
        struct component *c;
        size_t i;

        WARN_ON(!mutex_is_locked(&component_mutex));

        adev = __aggregate_find(parent, NULL);
        if (!adev)
                return;

        /* Unbind components in reverse order */
        for (i = adev->match->num; i--; )
                if (!adev->match->compare[i].duplicate) {
                        c = adev->match->compare[i].component;
                        component_unbind(c, adev, data);
                }
}
EXPORT_SYMBOL_GPL(component_unbind_all);

static int component_bind(struct component *component, struct aggregate_device *adev,
        void *data)
{
        int ret;

        /*
         * Each component initialises inside its own devres group.
         * This allows us to roll-back a failed component without
         * affecting anything else.
         */
        if (!devres_open_group(adev->parent, NULL, GFP_KERNEL))
                return -ENOMEM;

        /*
         * Also open a group for the device itself: this allows us
         * to release the resources claimed against the sub-device
         * at the appropriate moment.
         */
        if (!devres_open_group(component->dev, component, GFP_KERNEL)) {
                devres_release_group(adev->parent, NULL);
                return -ENOMEM;
        }

        dev_dbg(adev->parent, "binding %s (ops %ps)\n",
                dev_name(component->dev), component->ops);

        ret = component->ops->bind(component->dev, adev->parent, data);
        if (!ret) {
                component->bound = true;

                /*
                 * Close the component device's group so that resources
                 * allocated in the binding are encapsulated for removal
                 * at unbind.  Remove the group on the DRM device as we
                 * can clean those resources up independently.
                 */
                devres_close_group(component->dev, NULL);
                devres_remove_group(adev->parent, NULL);

                dev_info(adev->parent, "bound %s (ops %ps)\n",
                         dev_name(component->dev), component->ops);
        } else {
                devres_release_group(component->dev, NULL);
                devres_release_group(adev->parent, NULL);

                if (ret != -EPROBE_DEFER)
                        dev_err(adev->parent, "failed to bind %s (ops %ps): %d\n",
                                dev_name(component->dev), component->ops, ret);
        }

        return ret;
}

/**
 * component_bind_all - bind all components of an aggregate driver
 * @parent: parent device of the aggregate driver
 * @data: opaque pointer, passed to all components
 *
 * Binds all components of the aggregate @dev by passing @data to their
 * &component_ops.bind functions. Should be called from
 * &component_master_ops.bind.
 */
int component_bind_all(struct device *parent, void *data)
{
        struct aggregate_device *adev;
        struct component *c;
        size_t i;
        int ret = 0;

        WARN_ON(!mutex_is_locked(&component_mutex));

        adev = __aggregate_find(parent, NULL);
        if (!adev)
                return -EINVAL;

        /* Bind components in match order */
        for (i = 0; i < adev->match->num; i++)
                if (!adev->match->compare[i].duplicate) {
                        c = adev->match->compare[i].component;
                        ret = component_bind(c, adev, data);
                        if (ret)
                                break;
                }

        if (ret != 0) {
                for (; i > 0; i--)
                        if (!adev->match->compare[i - 1].duplicate) {
                                c = adev->match->compare[i - 1].component;
                                component_unbind(c, adev, data);
                        }
        }

        return ret;
}
EXPORT_SYMBOL_GPL(component_bind_all);

static int __component_add(struct device *dev, const struct component_ops *ops,
        int subcomponent)
{
        struct component *component;
        int ret;

        component = kzalloc_obj(*component);
        if (!component)
                return -ENOMEM;

        component->ops = ops;
        component->dev = dev;
        component->subcomponent = subcomponent;

        dev_dbg(dev, "adding component (ops %ps)\n", ops);

        mutex_lock(&component_mutex);
        list_add_tail(&component->node, &component_list);

        ret = try_to_bring_up_masters(component);
        if (ret < 0) {
                if (component->adev)
                        remove_component(component->adev, component);
                list_del(&component->node);

                kfree(component);
        }
        mutex_unlock(&component_mutex);

        return ret < 0 ? ret : 0;
}

/**
 * component_add_typed - register a component
 * @dev: component device
 * @ops: component callbacks
 * @subcomponent: nonzero identifier for subcomponents
 *
 * Register a new component for @dev. Functions in @ops will be call when the
 * aggregate driver is ready to bind the overall driver by calling
 * component_bind_all(). See also &struct component_ops.
 *
 * @subcomponent must be nonzero and is used to differentiate between multiple
 * components registered on the same device @dev. These components are match
 * using component_match_add_typed().
 *
 * The component needs to be unregistered at driver unload/disconnect by
 * calling component_del().
 *
 * See also component_add().
 */
int component_add_typed(struct device *dev, const struct component_ops *ops,
        int subcomponent)
{
        if (WARN_ON(subcomponent == 0))
                return -EINVAL;

        return __component_add(dev, ops, subcomponent);
}
EXPORT_SYMBOL_GPL(component_add_typed);

/**
 * component_add - register a component
 * @dev: component device
 * @ops: component callbacks
 *
 * Register a new component for @dev. Functions in @ops will be called when the
 * aggregate driver is ready to bind the overall driver by calling
 * component_bind_all(). See also &struct component_ops.
 *
 * The component needs to be unregistered at driver unload/disconnect by
 * calling component_del().
 *
 * See also component_add_typed() for a variant that allows multiple different
 * components on the same device.
 */
int component_add(struct device *dev, const struct component_ops *ops)
{
        return __component_add(dev, ops, 0);
}
EXPORT_SYMBOL_GPL(component_add);

/**
 * component_del - unregister a component
 * @dev: component device
 * @ops: component callbacks
 *
 * Unregister a component added with component_add(). If the component is bound
 * into an aggregate driver, this will force the entire aggregate driver, including
 * all its components, to be unbound.
 */
void component_del(struct device *dev, const struct component_ops *ops)
{
        struct component *c, *component = NULL;

        mutex_lock(&component_mutex);
        list_for_each_entry(c, &component_list, node)
                if (c->dev == dev && c->ops == ops) {
                        list_del(&c->node);
                        component = c;
                        break;
                }

        if (component && component->adev) {
                take_down_aggregate_device(component->adev);
                remove_component(component->adev, component);
        }

        mutex_unlock(&component_mutex);

        WARN_ON(!component);
        kfree(component);
}
EXPORT_SYMBOL_GPL(component_del);