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