component: Add documentation
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. v4: Remove a few superflous "This". Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 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> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190207232759.14553-1-daniel.vetter@ffwll.ch
This commit is contained in:
Daniel Vetter
parent
8834f5600c
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4d69c80e0d
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@ -0,0 +1,17 @@
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======================================
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Component Helper for Aggregate Drivers
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======================================
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.. kernel-doc:: drivers/base/component.c
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:doc: overview
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API
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===
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.. kernel-doc:: include/linux/component.h
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:internal:
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.. kernel-doc:: drivers/base/component.c
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:export:
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@ -1,6 +1,9 @@
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.. |struct dev_pm_domain| replace:: :c:type:`struct dev_pm_domain <dev_pm_domain>`
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.. |struct generic_pm_domain| replace:: :c:type:`struct generic_pm_domain <generic_pm_domain>`
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.. _device_link:
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============
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Device links
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============
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@ -22,6 +22,7 @@ available subsections can be seen below.
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device_connection
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dma-buf
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device_link
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component
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message-based
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sound
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frame-buffer
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@ -16,6 +16,32 @@
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#include <linux/slab.h>
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#include <linux/debugfs.h>
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/**
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* DOC: overview
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*
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* The component helper allows drivers to collect a pile of sub-devices,
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* including their bound drivers, into an aggregate driver. Various subsystems
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* already provide functions to get hold of such components, e.g.
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* of_clk_get_by_name(). The component helper can be used when such a
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* subsystem-specific way to find a device is not available: The component
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* helper fills the niche of aggregate drivers for specific hardware, where
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* further standardization into a subsystem would not be practical. The common
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* example is when a logical device (e.g. a DRM display driver) is spread around
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* the SoC on various component (scanout engines, blending blocks, transcoders
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* for various outputs and so on).
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*
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* The component helper also doesn't solve runtime dependencies, e.g. for system
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* suspend and resume operations. See also :ref:`device links<device_link>`.
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*
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* Components are registered using component_add() and unregistered with
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* component_del(), usually from the driver's probe and disconnect functions.
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*
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* Aggregate drivers first assemble a component match list of what they need
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* using component_match_add(). This is then registered as an aggregate driver
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* using component_master_add_with_match(), and unregistered using
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* component_master_del().
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*/
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struct component;
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struct component_match_array {
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@ -301,10 +327,24 @@ static int component_match_realloc(struct device *dev,
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return 0;
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}
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/*
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* Add a component to be matched, with a release function.
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/**
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* component_match_add_release - add a component match with release callback
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* @master: device with the aggregate driver
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* @matchptr: pointer to the list of component matches
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* @release: release function for @compare_data
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* @compare: compare function to match against all components
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* @compare_data: opaque pointer passed to the @compare function
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*
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* The match array is first created or extended if necessary.
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* Adds a new component match to the list stored in @matchptr, which the @master
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* aggregate driver needs to function. The list of component matches pointed to
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* by @matchptr must be initialized to NULL before adding the first match.
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*
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* The allocated match list in @matchptr is automatically released using devm
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* actions, where upon @release will be called to free any references held by
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* @compare_data, e.g. when @compare_data is a &device_node that must be
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* released with of_node_put().
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*
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* See also component_match_add().
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*/
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void component_match_add_release(struct device *master,
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struct component_match **matchptr,
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@ -367,6 +407,18 @@ static void free_master(struct master *master)
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kfree(master);
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}
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/**
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* component_master_add_with_match - register an aggregate driver
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* @dev: device with the aggregate driver
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* @ops: callbacks for the aggregate driver
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* @match: component match list for the aggregate driver
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*
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* Registers a new aggregate driver consisting of the components added to @match
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* by calling one of the component_match_add() functions. Once all components in
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* @match are available, it will be assembled by calling
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* &component_master_ops.bind from @ops. Must be unregistered by calling
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* component_master_del().
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*/
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int component_master_add_with_match(struct device *dev,
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const struct component_master_ops *ops,
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struct component_match *match)
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@ -403,6 +455,15 @@ int component_master_add_with_match(struct device *dev,
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}
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EXPORT_SYMBOL_GPL(component_master_add_with_match);
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/**
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* component_master_del - unregister an aggregate driver
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* @dev: device with the aggregate driver
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* @ops: callbacks for the aggregate driver
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*
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* Unregisters an aggregate driver registered with
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* component_master_add_with_match(). If necessary the aggregate driver is first
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* disassembled by calling &component_master_ops.unbind from @ops.
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*/
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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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@ -430,6 +491,15 @@ static void component_unbind(struct component *component,
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devres_release_group(component->dev, component);
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}
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/**
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* component_unbind_all - unbind all component to an aggregate driver
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* @master_dev: device with the aggregate driver
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* @data: opaque pointer, passed to all components
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*
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* Unbinds all components to the aggregate @dev by passing @data to their
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* &component_ops.unbind functions. Should be called from
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* &component_master_ops.unbind.
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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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@ -503,6 +573,15 @@ static int component_bind(struct component *component, struct master *master,
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return ret;
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}
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/**
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* component_bind_all - bind all component to an aggregate driver
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* @master_dev: device with the aggregate driver
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* @data: opaque pointer, passed to all components
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*
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* Binds all components to the aggregate @dev by passing @data to their
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* &component_ops.bind functions. Should be called from
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* &component_master_ops.bind.
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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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@ -537,6 +616,18 @@ int component_bind_all(struct device *master_dev, void *data)
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}
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EXPORT_SYMBOL_GPL(component_bind_all);
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/**
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* component_add - register a component
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* @dev: component device
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* @ops: component callbacks
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*
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* Register a new component for @dev. Functions in @ops will be called when the
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* aggregate driver is ready to bind the overall driver by calling
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* component_bind_all(). See also &struct component_ops.
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*
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* The component needs to be unregistered at driver unload/disconnect by calling
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* component_del().
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*/
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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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@ -568,6 +659,15 @@ int component_add(struct device *dev, const struct component_ops *ops)
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}
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EXPORT_SYMBOL_GPL(component_add);
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/**
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* component_del - unregister a component
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* @dev: component device
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* @ops: component callbacks
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*
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* Unregister a component added with component_add(). If the component is bound
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* into an aggregate driver, this will force the entire aggregate driver, including
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* all its components, to be unbound.
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*/
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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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@ -4,11 +4,31 @@
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#include <linux/stddef.h>
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struct device;
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/**
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* struct component_ops - callbacks for component drivers
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*
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* Components are registered with component_add() and unregistered with
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* component_del().
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*/
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struct component_ops {
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/**
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* @bind:
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*
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* Called through component_bind_all() when the aggregate driver is
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* ready to bind the overall driver.
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*/
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int (*bind)(struct device *comp, struct device *master,
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void *master_data);
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/**
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* @unbind:
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*
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* Called through component_unbind_all() when the aggregate driver is
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* ready to bind the overall driver, or when component_bind_all() fails
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* part-ways through and needs to unbind some already bound components.
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*/
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void (*unbind)(struct device *comp, struct device *master,
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void *master_data);
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};
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@ -21,8 +41,42 @@ void component_unbind_all(struct device *master, void *master_data);
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struct master;
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/**
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* struct component_master_ops - callback for the aggregate driver
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*
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* Aggregate drivers are registered with component_master_add_with_match() and
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* unregistered with component_master_del().
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*/
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struct component_master_ops {
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/**
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* @bind:
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*
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* Called when all components or the aggregate driver, as specified in
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* the match list passed to component_master_add_with_match(), are
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* ready. Usually there are 3 steps to bind an aggregate driver:
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*
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* 1. Allocate a structure for the aggregate driver.
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*
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* 2. Bind all components to the aggregate driver by calling
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* component_bind_all() with the aggregate driver structure as opaque
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* pointer data.
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*
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* 3. Register the aggregate driver with the subsystem to publish its
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* interfaces.
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*
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* Note that the lifetime of the aggregate driver does not align with
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* any of the underlying &struct device instances. Therefore devm cannot
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* be used and all resources acquired or allocated in this callback must
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* be explicitly released in the @unbind callback.
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*/
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int (*bind)(struct device *master);
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/**
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* @unbind:
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*
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* Called when either the aggregate driver, using
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* component_master_del(), or one of its components, using
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* component_del(), is unregistered.
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*/
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void (*unbind)(struct device *master);
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};
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@ -38,6 +92,22 @@ void component_match_add_release(struct device *master,
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void (*release)(struct device *, void *),
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int (*compare)(struct device *, void *), void *compare_data);
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/**
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* component_match_add - add a compent match
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* @master: device with the aggregate driver
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* @matchptr: pointer to the list of component matches
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* @compare: compare function to match against all components
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* @compare_data: opaque pointer passed to the @compare function
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*
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* Adds a new component match to the list stored in @matchptr, which the @master
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* aggregate driver needs to function. The list of component matches pointed to
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* by @matchptr must be initialized to NULL before adding the first match.
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*
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* The allocated match list in @matchptr is automatically released using devm
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* actions.
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*
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* See also component_match_add_release().
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*/
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static inline void component_match_add(struct device *master,
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struct component_match **matchptr,
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int (*compare)(struct device *, void *), void *compare_data)
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