diff options
Diffstat (limited to 'kernel/drivers/base/component.c')
| -rw-r--r-- | kernel/drivers/base/component.c | 512 |
1 files changed, 512 insertions, 0 deletions
diff --git a/kernel/drivers/base/component.c b/kernel/drivers/base/component.c new file mode 100644 index 000000000..f748430bb --- /dev/null +++ b/kernel/drivers/base/component.c @@ -0,0 +1,512 @@ +/* + * 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 (IS_ERR(match)) + return; + } + + match->compare[match->num].fn = compare; + match->compare[match->num].data = compare_data; + match->num++; +} +EXPORT_SYMBOL(component_match_add); + +int component_master_add_with_match(struct device *dev, + const struct component_master_ops *ops, + struct component_match *match) +{ + struct master *master; + int ret; + + if (ops->add_components && match) + return -EINVAL; + + if (match) { + /* Reallocate the match array for its true size */ + match = component_match_realloc(dev, match, match->num); + if (IS_ERR(match)) + return PTR_ERR(match); + } + + master = kzalloc(sizeof(*master), GFP_KERNEL); + if (!master) + return -ENOMEM; + + master->dev = dev; + master->ops = ops; + master->match = match; + 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_with_match); + +int component_master_add(struct device *dev, + const struct component_master_ops *ops) +{ + return component_master_add_with_match(dev, ops, NULL); +} +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"); |