Someone owes me a beer ...
While typing these I think doing an s/component_master/aggregate/ would be useful: - it's shorter :-) - I think component/aggregate is much more meaningful naming than component/puppetmaster or something like that. At least to my English ear "aggregate" emphasizes much more the "assemble a pile of things into something bigger" aspect, and there's not really much of a control hierarchy between aggregate and constituing components.
But that's way more than a quick doc typing exercise ...
Thanks to Ram for commenting on an initial draft of these docs.
v2: Review from Rafael: - git add Documenation/driver-api/component.rst - lots of polish to the wording + spelling fixes.
v3: Review from Russell: - s/framework/helper - clarify the documentation for component_match_add functions.
Cc: "C, Ramalingam" ramalingam.c@intel.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Russell King rmk+kernel@arm.linux.org.uk Cc: Rafael J. Wysocki rafael@kernel.org Cc: Jaroslav Kysela perex@perex.cz Cc: Takashi Iwai tiwai@suse.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Jani Nikula jani.nikula@linux.intel.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- Documentation/driver-api/component.rst | 17 ++++ Documentation/driver-api/device_link.rst | 3 + Documentation/driver-api/index.rst | 1 + drivers/base/component.c | 107 ++++++++++++++++++++++- include/linux/component.h | 71 +++++++++++++++ 5 files changed, 196 insertions(+), 3 deletions(-) create mode 100644 Documentation/driver-api/component.rst
diff --git a/Documentation/driver-api/component.rst b/Documentation/driver-api/component.rst new file mode 100644 index 000000000000..2da4a8f20607 --- /dev/null +++ b/Documentation/driver-api/component.rst @@ -0,0 +1,17 @@ +====================================== +Component Helper for Aggregate Drivers +====================================== + +.. kernel-doc:: drivers/base/component.c + :doc: overview + + +API +=== + +.. kernel-doc:: include/linux/component.h + :internal: + +.. kernel-doc:: drivers/base/component.c + :export: + diff --git a/Documentation/driver-api/device_link.rst b/Documentation/driver-api/device_link.rst index d6763272e747..2d5919b2b337 100644 --- a/Documentation/driver-api/device_link.rst +++ b/Documentation/driver-api/device_link.rst @@ -1,6 +1,9 @@ .. |struct dev_pm_domain| replace:: :c:type:`struct dev_pm_domain <dev_pm_domain>` .. |struct generic_pm_domain| replace:: :c:type:`struct generic_pm_domain <generic_pm_domain>`
+ +.. _device_link: + ============ Device links ============ diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index ab38ced66a44..c0b600ed9961 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -22,6 +22,7 @@ available subsections can be seen below. device_connection dma-buf device_link + component message-based sound frame-buffer diff --git a/drivers/base/component.c b/drivers/base/component.c index ddcea8739c12..f34d4b784709 100644 --- a/drivers/base/component.c +++ b/drivers/base/component.c @@ -16,6 +16,32 @@ #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 component (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 { @@ -301,10 +327,25 @@ static int component_match_realloc(struct device *dev, return 0; }
-/* - * Add a component to be matched, with a release function. +/** + * component_match_add_release - add a component match 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 + * + * This 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. + * + * 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(). * - * The match array is first created or extended if necessary. + * See also component_match_add(). */ void component_match_add_release(struct device *master, struct component_match **matchptr, @@ -367,6 +408,18 @@ static void free_master(struct master *master) 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) @@ -403,6 +456,15 @@ int component_master_add_with_match(struct device *dev, } 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) { @@ -430,6 +492,15 @@ static void component_unbind(struct component *component, devres_release_group(component->dev, component); }
+/** + * component_unbind_all - unbind all component to an aggregate driver + * @master_dev: device with the aggregate driver + * @data: opaque pointer, passed to all components + * + * Unbinds all components to 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; @@ -503,6 +574,15 @@ static int component_bind(struct component *component, struct master *master, return ret; }
+/** + * component_bind_all - bind all component to an aggregate driver + * @master_dev: device with the aggregate driver + * @data: opaque pointer, passed to all components + * + * Binds all components to 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; @@ -537,6 +617,18 @@ int component_bind_all(struct device *master_dev, void *data) } EXPORT_SYMBOL_GPL(component_bind_all);
+/** + * 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(). + */ int component_add(struct device *dev, const struct component_ops *ops) { struct component *component; @@ -568,6 +660,15 @@ int component_add(struct device *dev, const struct component_ops *ops) } 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; diff --git a/include/linux/component.h b/include/linux/component.h index e71fbbbc74e2..4911598b4c42 100644 --- a/include/linux/component.h +++ b/include/linux/component.h @@ -4,11 +4,31 @@
#include <linux/stddef.h>
+ struct device;
+/** + * struct component_ops - callbacks for component drivers + * + * Components are registered with component_add() and unregistered with + * component_del(). + */ struct component_ops { + /** + * @bind: + * + * Called through component_bind_all() when the aggregate driver is + * ready to bind the overall driver. + */ int (*bind)(struct device *comp, struct device *master, void *master_data); + /** + * @unbind: + * + * Called through component_unbind_all() when the aggregate driver is + * ready to bind the overall driver, or when component_bind_all() fails + * part-ways through and needs to unbind some already bound components. + */ void (*unbind)(struct device *comp, struct device *master, void *master_data); }; @@ -21,8 +41,42 @@ void component_unbind_all(struct device *master, void *master_data);
struct master;
+/** + * struct component_master_ops - callback for the aggregate driver + * + * Aggregate drivers are registered with component_master_add_with_match() and + * unregistered with component_master_del(). + */ struct component_master_ops { + /** + * @bind: + * + * Called when all components or the aggregate driver, as specified in + * the match list passed to component_master_add_with_match(), are + * ready. Usually there are 3 steps to bind an aggregate driver: + * + * 1. Allocate a structure for the aggregate driver. + * + * 2. Bind all components to the aggregate driver by calling + * component_bind_all() with the aggregate driver structure as opaque + * pointer data. + * + * 3. Register the aggregate driver with the subsystem to publish its + * interfaces. + * + * Note that the lifetime of the aggregate driver does not align with + * any of the underlying &struct device instances. Therefore devm cannot + * be used and all resources acquired or allocated in this callback must + * be explicitly released in the @unbind callback. + */ int (*bind)(struct device *master); + /** + * @unbind: + * + * Called when either the aggregate driver, using + * component_master_del(), or one of its components, using + * component_del(), is unregistered. + */ void (*unbind)(struct device *master); };
@@ -38,6 +92,23 @@ void component_match_add_release(struct device *master, void (*release)(struct device *, void *), int (*compare)(struct device *, void *), void *compare_data);
+/** + * component_match_add - add a compent match + * @master: device with the aggregate driver + * @matchptr: pointer to the list of component matches + * @compare: compare function to match against all components + * @compare_data: opaque pointer passed to the @compare function + * + * This 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. + * + * The allocated match list in @matchptr is automatically released using devm + * actions. + * + * See also component_match_add_release(). + */ static inline void component_match_add(struct device *master, struct component_match **matchptr, int (*compare)(struct device *, void *), void *compare_data)