// 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, "%-40s %20s\n", "aggregate_device name", "status");
seq_puts(s, "-------------------------------------------------------------\n");
seq_printf(s, "%-40s %20s\n\n",
dev_name(m->parent), m->bound ? "bound" : "not bound");
seq_printf(s, "%-40s %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, "%-40s %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_array(num, sizeof(*new), GFP_KERNEL);
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(sizeof(*adev), GFP_KERNEL);
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);
static void component_unbind(struct component *component,
struct aggregate_device *adev, void *data)
{
WARN_ON(!component->bound);
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(sizeof(*component), GFP_KERNEL);
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);
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