Commit 4d69c80e authored by Daniel Vetter's avatar Daniel Vetter
Browse files

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: default avatarRafael 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190207232759.14553-1-daniel.vetter@ffwll.ch
parent 8834f560

Documentation/driver-api/component.rst

0 → 100644
+17 −0
Original line number Diff line number Diff line 
======================================

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:

Documentation/driver-api/device_link.rst

+3 −0
Original line number Diff line number Diff line 
.. |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

============

Documentation/driver-api/index.rst

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ available subsections can be seen below. 
   device_connection

   dma-buf

   device_link

   component

   message-based

   sound

   frame-buffer

drivers/base/component.c

+103 −3
Original line number Diff line number Diff line
@@ -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

 *

 * 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 +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;

include/linux/component.h

+70 −0
Original line number Diff line number Diff line
@@ -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)

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