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component: Add documentation

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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 2019-02-08 00:27:56 +01:00
parent 8834f5600c
commit 4d69c80e0d
5 changed files with 194 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
Documentation/driver-api/component.rst Normal file
View File

@ -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:

3
Documentation/driver-api/device_link.rst
View File

@ -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
============

1
Documentation/driver-api/index.rst
View File

@ -22,6 +22,7 @@ available subsections can be seen below.
device_connection
dma-buf
device_link
component
message-based
sound
frame-buffer

106
drivers/base/component.c
View File

@ -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 +327,24 @@ 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
*
* The match array is first created or extended if necessary.
* 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().
*
* See also component_match_add().
*/
void component_match_add_release(struct device *master,
struct component_match **matchptr,
@ -367,6 +407,18 @@ 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 +455,15 @@ 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 +491,15 @@ 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 +573,15 @@ 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 +616,18 @@ 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 +659,15 @@ 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;

70
include/linux/component.h
View File

@ -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 +92,22 @@ 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
*
* 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)