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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 component_match {
size_t alloc;
size_t num;
struct {
void *data;
int (*fn)(struct device *, void *);
} compare[0];
};
struct master {
struct list_head node;
struct list_head components;
bool bound;
const struct component_master_ops *ops;
struct device *dev;
struct component_match *match;
};
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);
static int find_components(struct master *master)
{
struct component_match *match = master->match;
size_t i;
int ret = 0;
if (!match) {
/*
* Search the list of components, looking for components that
* belong to this master, and attach them to the master.
*/
return master->ops->add_components(master->dev, master);
}
/*
* Scan the array of match functions and attach
* any components which are found to this master.
*/
for (i = 0; i < match->num; i++) {
ret = component_master_add_child(master,
match->compare[i].fn,
match->compare[i].data);
if (ret)
break;
}
return ret;
}
/* 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 (find_components(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);
}
static size_t component_match_size(size_t num)
{
return offsetof(struct component_match, compare[num]);
}
static struct component_match *component_match_realloc(struct device *dev,
struct component_match *match, size_t num)
{
struct component_match *new;
if (match && match->alloc == num)
return match;
new = devm_kmalloc(dev, component_match_size(num), GFP_KERNEL);
if (!new)
return ERR_PTR(-ENOMEM);
if (match) {
memcpy(new, match, component_match_size(min(match->num, num)));
devm_kfree(dev, match);
} else {
new->num = 0;
}
new->alloc = num;
return new;
}
/*
* Add a component to be matched.
*
* The match array is first created or extended if necessary.
*/
void component_match_add(struct device *dev, struct component_match **matchptr,
int (*compare)(struct device *, void *), void *compare_data)
{
struct component_match *match = *matchptr;
if (IS_ERR(match))
return;
if (!match || match->num == match->alloc) {
size_t new_size = match ? match->alloc + 16 : 15;
match = component_match_realloc(dev, match, new_size);
*matchptr = match;
if (<
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