diff options
Diffstat (limited to 'drivers/base/component.c')
| -rw-r--r-- | drivers/base/component.c | 779 |
1 files changed, 779 insertions, 0 deletions
diff --git a/drivers/base/component.c b/drivers/base/component.c new file mode 100644 index 000000000..dcfbe7251 --- /dev/null +++ b/drivers/base/component.c @@ -0,0 +1,779 @@ +// 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/mutex.h> +#include <linux/slab.h> +#include <linux/debugfs.h> + +/** + * DOC: overview + * + * The component helper allows drivers to collect a pile of sub-devices, + * including their bound drivers, into an aggregate driver. Various subsystems + * already provide functions to get hold of such components, e.g. + * of_clk_get_by_name(). The component helper can be used when such a + * subsystem-specific way to find a device is not available: The component + * helper fills the niche of aggregate drivers for specific hardware, where + * further standardization into a subsystem would not be practical. The common + * example is when a logical device (e.g. a DRM display driver) is spread around + * the SoC on various components (scanout engines, blending blocks, transcoders + * for various outputs and so on). + * + * The component helper also doesn't solve runtime dependencies, e.g. for system + * suspend and resume operations. See also :ref:`device links<device_link>`. + * + * Components are registered using component_add() and unregistered with + * component_del(), usually from the driver's probe and disconnect functions. + * + * Aggregate drivers first assemble a component match list of what they need + * using component_match_add(). This is then registered as an aggregate driver + * using component_master_add_with_match(), and unregistered using + * component_master_del(). + */ + +struct component; + +struct component_match_array { + void *data; + int (*compare)(struct device *, void *); + int (*compare_typed)(struct device *, int, 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; + int subcomponent; + 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 component *component = match->compare[i].component; + + seq_printf(s, "%-40s %20s\n", + component ? dev_name(component->dev) : "(unknown)", + component ? (component->bound ? "bound" : "not bound") : "not registered"); + } + mutex_unlock(&component_mutex); + + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(component_devices); + +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, + struct component_match_array *mc) +{ + struct component *c; + + list_for_each_entry(c, &component_list, node) { + if (c->master && c->master != master) + continue; + + if (mc->compare && mc->compare(c->dev, mc->data)) + return c; + + if (mc->compare_typed && + mc->compare_typed(c->dev, c->subcomponent, mc->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); + 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); + if (ret != -EPROBE_DEFER) + 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; +} + +static void __component_match_add(struct device *master, + struct component_match **matchptr, + void (*release)(struct device *, void *), + int (*compare)(struct device *, void *), + int (*compare_typed)(struct device *, int, 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].compare_typed = compare_typed; + match->compare[match->num].release = release; + match->compare[match->num].data = compare_data; + match->compare[match->num].component = NULL; + match->num++; +} + +/** + * component_match_add_release - add a component match entry with release callback + * @master: device with the aggregate driver + * @matchptr: pointer to the list of component matches + * @release: release function for @compare_data + * @compare: compare function to match against all components + * @compare_data: opaque pointer passed to the @compare function + * + * Adds a new component match to the list stored in @matchptr, which the @master + * aggregate driver needs to function. The list of component matches pointed to + * by @matchptr must be initialized to NULL before adding the first match. This + * only matches against components added with component_add(). + * + * The allocated match list in @matchptr is automatically released using devm + * actions, where upon @release will be called to free any references held by + * @compare_data, e.g. when @compare_data is a &device_node that must be + * released with of_node_put(). + * + * See also component_match_add() and component_match_add_typed(). + */ +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) +{ + __component_match_add(master, matchptr, release, compare, NULL, + compare_data); +} +EXPORT_SYMBOL(component_match_add_release); + +/** + * component_match_add_typed - add a component match entry for a typed component + * @master: device with the aggregate driver + * @matchptr: pointer to the list of component matches + * @compare_typed: compare function to match against all typed components + * @compare_data: opaque pointer passed to the @compare function + * + * Adds a new component match to the list stored in @matchptr, which the @master + * aggregate driver needs to function. The list of component matches pointed to + * by @matchptr must be initialized to NULL before adding the first match. This + * only matches against components added with component_add_typed(). + * + * The allocated match list in @matchptr is automatically released using devm + * actions. + * + * See also component_match_add_release() and component_match_add_typed(). + */ +void component_match_add_typed(struct device *master, + struct component_match **matchptr, + int (*compare_typed)(struct device *, int, void *), void *compare_data) +{ + __component_match_add(master, matchptr, NULL, NULL, compare_typed, + compare_data); +} +EXPORT_SYMBOL(component_match_add_typed); + +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); +} + +/** + * component_master_add_with_match - register an aggregate driver + * @dev: device with the aggregate driver + * @ops: callbacks for the aggregate driver + * @match: component match list for the aggregate driver + * + * Registers a new aggregate driver consisting of the components added to @match + * by calling one of the component_match_add() functions. Once all components in + * @match are available, it will be assembled by calling + * &component_master_ops.bind from @ops. Must be unregistered by calling + * component_master_del(). + */ +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); + +/** + * component_master_del - unregister an aggregate driver + * @dev: device with the aggregate driver + * @ops: callbacks for the aggregate driver + * + * Unregisters an aggregate driver registered with + * component_master_add_with_match(). If necessary the aggregate driver is first + * disassembled by calling &component_master_ops.unbind from @ops. + */ +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); + + if (component->ops && component->ops->unbind) + 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); +} + +/** + * component_unbind_all - unbind all components of an aggregate driver + * @master_dev: device with the aggregate driver + * @data: opaque pointer, passed to all components + * + * Unbinds all components of the aggregate @dev by passing @data to their + * &component_ops.unbind functions. Should be called from + * &component_master_ops.unbind. + */ +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); + + if (ret != -EPROBE_DEFER) + dev_err(master->dev, "failed to bind %s (ops %ps): %d\n", + dev_name(component->dev), component->ops, ret); + } + + return ret; +} + +/** + * component_bind_all - bind all components of an aggregate driver + * @master_dev: device with the aggregate driver + * @data: opaque pointer, passed to all components + * + * Binds all components of the aggregate @dev by passing @data to their + * &component_ops.bind functions. Should be called from + * &component_master_ops.bind. + */ +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 > 0; i--) + if (!master->match->compare[i - 1].duplicate) { + c = master->match->compare[i - 1].component; + component_unbind(c, master, data); + } + } + + return ret; +} +EXPORT_SYMBOL_GPL(component_bind_all); + +static int __component_add(struct device *dev, const struct component_ops *ops, + int subcomponent) +{ + struct component *component; + int ret; + + component = kzalloc(sizeof(*component), GFP_KERNEL); + if (!component) + return -ENOMEM; + + component->ops = ops; + component->dev = dev; + component->subcomponent = subcomponent; + + 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; +} + +/** + * component_add_typed - register a component + * @dev: component device + * @ops: component callbacks + * @subcomponent: nonzero identifier for subcomponents + * + * Register a new component for @dev. Functions in @ops will be call when the + * aggregate driver is ready to bind the overall driver by calling + * component_bind_all(). See also &struct component_ops. + * + * @subcomponent must be nonzero and is used to differentiate between multiple + * components registerd on the same device @dev. These components are match + * using component_match_add_typed(). + * + * The component needs to be unregistered at driver unload/disconnect by + * calling component_del(). + * + * See also component_add(). + */ +int component_add_typed(struct device *dev, const struct component_ops *ops, + int subcomponent) +{ + if (WARN_ON(subcomponent == 0)) + return -EINVAL; + + return __component_add(dev, ops, subcomponent); +} +EXPORT_SYMBOL_GPL(component_add_typed); + +/** + * component_add - register a component + * @dev: component device + * @ops: component callbacks + * + * Register a new component for @dev. Functions in @ops will be called when the + * aggregate driver is ready to bind the overall driver by calling + * component_bind_all(). See also &struct component_ops. + * + * The component needs to be unregistered at driver unload/disconnect by + * calling component_del(). + * + * See also component_add_typed() for a variant that allows multipled different + * components on the same device. + */ +int component_add(struct device *dev, const struct component_ops *ops) +{ + return __component_add(dev, ops, 0); +} +EXPORT_SYMBOL_GPL(component_add); + +/** + * component_del - unregister a component + * @dev: component device + * @ops: component callbacks + * + * Unregister a component added with component_add(). If the component is bound + * into an aggregate driver, this will force the entire aggregate driver, including + * all its components, to be unbound. + */ +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); |