linux/drivers/base/component.c
Maciej Purski 59e73854b5 component: add debugfs support
Currently there is no information in any vfs about which devices
a master component consists of, what makes debugging hard if
one of the component devices fails to register.

Add 'device_component' directory to debugfs. Create a new file for each
component master, when it has been added. Remove it on a master
deletion. Show a list of devices required by the given master and their
status (registered or not). This provides an easy way to check, which
device has failed to register if the given master device is not
available in the system.

Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-12-18 16:51:11 +01:00

606 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Componentized device handling.
*
* 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>
#include <linux/debugfs.h>
struct component;
struct component_match_array {
void *data;
int (*compare)(struct device *, 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 master {
struct list_head node;
bool bound;
const struct component_master_ops *ops;
struct device *dev;
struct component_match *match;
struct dentry *dentry;
};
struct component {
struct list_head 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);
#ifdef CONFIG_DEBUG_FS
static struct dentry *component_debugfs_dir;
static int component_devices_show(struct seq_file *s, void *data)
{
struct master *m = s->private;
struct component_match *match = m->match;
size_t i;
mutex_lock(&component_mutex);
seq_printf(s, "%-40s %20s\n", "master name", "status");
seq_puts(s, "-------------------------------------------------------------\n");
seq_printf(s, "%-40s %20s\n\n",
dev_name(m->dev), 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 device *d = (struct device *)match->compare[i].data;
seq_printf(s, "%-40s %20s\n", dev_name(d),
match->compare[i].component ?
"registered" : "not registered");
}
mutex_unlock(&component_mutex);
return 0;
}
static int component_devices_open(struct inode *inode, struct file *file)
{
return single_open(file, component_devices_show, inode->i_private);
}
static const struct file_operations component_devices_fops = {
.open = component_devices_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
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_master_debugfs_add(struct master *m)
{
m->dentry = debugfs_create_file(dev_name(m->dev), 0444,
component_debugfs_dir,
m, &component_devices_fops);
}
static void component_master_debugfs_del(struct master *m)
{
debugfs_remove(m->dentry);
m->dentry = NULL;
}
#else
static void component_master_debugfs_add(struct master *m)
{ }
static void component_master_debugfs_del(struct master *m)
{ }
#endif
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;
}
static struct component *find_component(struct master *master,
int (*compare)(struct device *, void *), void *compare_data)
{
struct component *c;
list_for_each_entry(c, &component_list, node) {
if (c->master && c->master != master)
continue;
if (compare(c->dev, compare_data))
return c;
}
return NULL;
}
static int find_components(struct master *master)
{
struct component_match *match = master->match;
size_t i;
int ret = 0;
/*
* Scan the array of match functions and attach
* any components which are found to this master.
*/
for (i = 0; i < match->num; i++) {
struct component_match_array *mc = &match->compare[i];
struct component *c;
dev_dbg(master->dev, "Looking for component %zu\n", i);
if (match->compare[i].component)
continue;
c = find_component(master, mc->compare, mc->data);
if (!c) {
ret = -ENXIO;
break;
}
dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master);
/* Attach this component to the master */
match->compare[i].duplicate = !!c->master;
match->compare[i].component = c;
c->master = master;
}
return ret;
}
/* Detach component from associated master */
static void remove_component(struct master *master, struct component *c)
{
size_t i;
/* Detach the component from this master. */
for (i = 0; i < master->match->num; i++)
if (master->match->compare[i].component == c)
master->match->compare[i].component = NULL;
}
/*
* 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;
dev_dbg(master->dev, "trying to bring up master\n");
if (find_components(master)) {
dev_dbg(master->dev, "master has incomplete components\n");
return 0;
}
if (component && component->master != master) {
dev_dbg(master->dev, "master is not for this component (%s)\n",
dev_name(component->dev));
return 0;
}
if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
return -ENOMEM;
/* 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);
return ret;
}
master->bound = true;
return 1;
}
static int try_to_bring_up_masters(struct component *component)
{
struct master *m;
int ret = 0;
list_for_each_entry(m, &masters, node) {
if (!m->bound) {
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;
}
}
static void component_match_release(struct device *master,
struct component_match *match)
{
unsigned int i;
for (i = 0; i < match->num; i++) {
struct component_match_array *mc = &match->compare[i];
if (mc->release)
mc->release(master, mc->data);
}
kfree(match->compare);
}
static void devm_component_match_release(struct device *dev, void *res)
{
component_match_release(dev, res);
}
static int component_match_realloc(struct device *dev,
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;
}
/*
* Add a component to be matched, with a release function.
*
* The match array is first created or extended if necessary.
*/
void component_match_add_release(struct device *master,
struct component_match **matchptr,
void (*release)(struct device *, void *),
int (*compare)(struct device *, 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(master, match);
*matchptr = match;
}
if (match->num == match->alloc) {
size_t new_size = match->alloc + 16;
int ret;
ret = component_match_realloc(master, match, new_size);
if (ret) {
*matchptr = ERR_PTR(ret);
return;
}
}
match->compare[match->num].compare = compare;
match->compare[match->num].release = release;
match->compare[match->num].data = compare_data;
match->compare[match->num].component = NULL;
match->num++;
}
EXPORT_SYMBOL(component_match_add_release);
static void free_master(struct master *master)
{
struct component_match *match = master->match;
int i;
component_master_debugfs_del(master);
list_del(&master->node);
if (match) {
for (i = 0; i < match->num; i++) {
struct component *c = match->compare[i].component;
if (c)
c->master = NULL;
}
}
kfree(master);
}
int component_master_add_with_match(struct device *dev,
const struct component_master_ops *ops,
struct component_match *match)
{
struct master *master;
int ret;
/* Reallocate the match array for its true size */
ret = component_match_realloc(dev, match, match->num);
if (ret)
return ret;
master = kzalloc(sizeof(*master), GFP_KERNEL);
if (!master)
return -ENOMEM;
master->dev = dev;
master->ops = ops;
master->match = match;
component_master_debugfs_add(master);
/* 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)
free_master(master);
mutex_unlock(&component_mutex);
return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(component_master_add_with_match);
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);
free_master(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;
size_t i;
WARN_ON(!mutex_is_locked(&component_mutex));
master = __master_find(master_dev, NULL);
if (!master)
return;
/* Unbind components in reverse order */
for (i = master->match->num; i--; )
if (!master->match->compare[i].duplicate) {
c = master->match->compare[i].component;
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;
size_t i;
int ret = 0;
WARN_ON(!mutex_is_locked(&component_mutex));
master = __master_find(master_dev, NULL);
if (!master)
return -EINVAL;
/* Bind components in match order */
for (i = 0; i < master->match->num; i++)
if (!master->match->compare[i].duplicate) {
c = master->match->compare[i].component;
ret = component_bind(c, master, data);
if (ret)
break;
}
if (ret != 0) {
for (; i--; )
if (!master->match->compare[i].duplicate) {
c = master->match->compare[i].component;
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) {
if (component->master)
remove_component(component->master, component);
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);
remove_component(component->master, component);
}
mutex_unlock(&component_mutex);
WARN_ON(!component);
kfree(component);
}
EXPORT_SYMBOL_GPL(component_del);
MODULE_LICENSE("GPL v2");