linux/drivers/base/component.c

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/*
* Componentized device handling.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This is work in progress. We gather up the component devices into a list,
* and bind them when instructed. At the moment, we're specific to the DRM
* subsystem, and only handles one master device, but this doesn't have to be
* the case.
*/
#include <linux/component.h>
#include <linux/device.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
struct master {
struct list_head node;
struct list_head components;
bool bound;
const struct component_master_ops *ops;
struct device *dev;
};
struct component {
struct list_head node;
struct list_head master_node;
struct master *master;
bool bound;
const struct component_ops *ops;
struct device *dev;
};
static DEFINE_MUTEX(component_mutex);
static LIST_HEAD(component_list);
static LIST_HEAD(masters);
static struct master *__master_find(struct device *dev,
const struct component_master_ops *ops)
{
struct master *m;
list_for_each_entry(m, &masters, node)
if (m->dev == dev && (!ops || m->ops == ops))
return m;
return NULL;
}
/* Attach an unattached component to a master. */
static void component_attach_master(struct master *master, struct component *c)
{
c->master = master;
list_add_tail(&c->master_node, &master->components);
}
/* Detach a component from a master. */
static void component_detach_master(struct master *master, struct component *c)
{
list_del(&c->master_node);
c->master = NULL;
}
/*
* Add a component to a master, finding the component via the compare
* function and compare data. This is safe to call for duplicate matches
* and will not result in the same component being added multiple times.
*/
int component_master_add_child(struct master *master,
int (*compare)(struct device *, void *), void *compare_data)
{
struct component *c;
int ret = -ENXIO;
list_for_each_entry(c, &component_list, node) {
if (c->master && c->master != master)
continue;
if (compare(c->dev, compare_data)) {
if (!c->master)
component_attach_master(master, c);
ret = 0;
break;
}
}
return ret;
}
EXPORT_SYMBOL_GPL(component_master_add_child);
/* Detach all attached components from this master */
static void master_remove_components(struct master *master)
{
while (!list_empty(&master->components)) {
struct component *c = list_first_entry(&master->components,
struct component, master_node);
WARN_ON(c->master != master);
component_detach_master(master, c);
}
}
/*
* Try to bring up a master. If component is NULL, we're interested in
* this master, otherwise it's a component which must be present to try
* and bring up the master.
*
* Returns 1 for successful bringup, 0 if not ready, or -ve errno.
*/
static int try_to_bring_up_master(struct master *master,
struct component *component)
{
int ret;
if (master->bound)
return 0;
/*
* Search the list of components, looking for components that
* belong to this master, and attach them to the master.
*/
if (master->ops->add_components(master->dev, master)) {
/* Failed to find all components */
ret = 0;
goto out;
}
if (component && component->master != master) {
ret = 0;
goto out;
}
if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) {
ret = -ENOMEM;
goto out;
}
/* Found all components */
ret = master->ops->bind(master->dev);
if (ret < 0) {
devres_release_group(master->dev, NULL);
dev_info(master->dev, "master bind failed: %d\n", ret);
goto out;
}
master->bound = true;
return 1;
out:
master_remove_components(master);
return ret;
}
static int try_to_bring_up_masters(struct component *component)
{
struct master *m;
int ret = 0;
list_for_each_entry(m, &masters, node) {
ret = try_to_bring_up_master(m, component);
if (ret != 0)
break;
}
return ret;
}
static void take_down_master(struct master *master)
{
if (master->bound) {
master->ops->unbind(master->dev);
devres_release_group(master->dev, NULL);
master->bound = false;
}
master_remove_components(master);
}
int component_master_add(struct device *dev,
const struct component_master_ops *ops)
{
struct master *master;
int ret;
master = kzalloc(sizeof(*master), GFP_KERNEL);
if (!master)
return -ENOMEM;
master->dev = dev;
master->ops = ops;
INIT_LIST_HEAD(&master->components);
/* Add to the list of available masters. */
mutex_lock(&component_mutex);
list_add(&master->node, &masters);
ret = try_to_bring_up_master(master, NULL);
if (ret < 0) {
/* Delete off the list if we weren't successful */
list_del(&master->node);
kfree(master);
}
mutex_unlock(&component_mutex);
return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(component_master_add);
void component_master_del(struct device *dev,
const struct component_master_ops *ops)
{
struct master *master;
mutex_lock(&component_mutex);
master = __master_find(dev, ops);
if (master) {
take_down_master(master);
list_del(&master->node);
kfree(master);
}
mutex_unlock(&component_mutex);
}
EXPORT_SYMBOL_GPL(component_master_del);
static void component_unbind(struct component *component,
struct master *master, void *data)
{
WARN_ON(!component->bound);
component->ops->unbind(component->dev, master->dev, data);
component->bound = false;
/* Release all resources claimed in the binding of this component */
devres_release_group(component->dev, component);
}
void component_unbind_all(struct device *master_dev, void *data)
{
struct master *master;
struct component *c;
WARN_ON(!mutex_is_locked(&component_mutex));
master = __master_find(master_dev, NULL);
if (!master)
return;
list_for_each_entry_reverse(c, &master->components, master_node)
component_unbind(c, master, data);
}
EXPORT_SYMBOL_GPL(component_unbind_all);
static int component_bind(struct component *component, struct master *master,
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(master->dev, 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(master->dev, NULL);
return -ENOMEM;
}
dev_dbg(master->dev, "binding %s (ops %ps)\n",
dev_name(component->dev), component->ops);
ret = component->ops->bind(component->dev, master->dev, 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(master->dev, NULL);
dev_info(master->dev, "bound %s (ops %ps)\n",
dev_name(component->dev), component->ops);
} else {
devres_release_group(component->dev, NULL);
devres_release_group(master->dev, NULL);
dev_err(master->dev, "failed to bind %s (ops %ps): %d\n",
dev_name(component->dev), component->ops, ret);
}
return ret;
}
int component_bind_all(struct device *master_dev, void *data)
{
struct master *master;
struct component *c;
int ret = 0;
WARN_ON(!mutex_is_locked(&component_mutex));
master = __master_find(master_dev, NULL);
if (!master)
return -EINVAL;
list_for_each_entry(c, &master->components, master_node) {
ret = component_bind(c, master, data);
if (ret)
break;
}
if (ret != 0) {
list_for_each_entry_continue_reverse(c, &master->components,
master_node)
component_unbind(c, master, data);
}
return ret;
}
EXPORT_SYMBOL_GPL(component_bind_all);
int component_add(struct device *dev, const struct component_ops *ops)
{
struct component *component;
int ret;
component = kzalloc(sizeof(*component), GFP_KERNEL);
if (!component)
return -ENOMEM;
component->ops = ops;
component->dev = dev;
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) {
list_del(&component->node);
kfree(component);
}
mutex_unlock(&component_mutex);
return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(component_add);
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->master)
take_down_master(component->master);
mutex_unlock(&component_mutex);
WARN_ON(!component);
kfree(component);
}
EXPORT_SYMBOL_GPL(component_del);
MODULE_LICENSE("GPL v2");