[1/4] component: Add documentation

Submitted by Daniel Vetter on Feb. 7, 2019, 11:27 p.m.

Details

Message ID 20190207232759.14553-1-daniel.vetter@ffwll.ch
State Accepted
Commit 4d69c80e0d0fd8cf12d985841eb0fce5c29819ad
Headers show
Series "Series without cover letter" ( rev: 1 ) in Intel GFX

Not browsing as part of any series.

Commit Message

Daniel Vetter Feb. 7, 2019, 11:27 p.m.
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>
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                 | 106 ++++++++++++++++++++++-
 include/linux/component.h                |  70 +++++++++++++++
 5 files changed, 194 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/driver-api/component.rst

Patch hide | download patch | download mbox

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..1624c2a892a5 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 +327,24 @@  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;
diff --git a/include/linux/component.h b/include/linux/component.h
index e71fbbbc74e2..83da25bdf59c 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 +92,22 @@  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)

Comments

On Fri, Feb 08, 2019 at 12:27:56AM +0100, Daniel Vetter wrote:
> 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>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Thanks for doing this!

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On Fri, Feb 08, 2019 at 12:51:23PM +0100, Greg Kroah-Hartman wrote:
> On Fri, Feb 08, 2019 at 12:27:56AM +0100, Daniel Vetter wrote:
> > 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>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> 
> Thanks for doing this!
> 
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Thanks for reviewing (obviously includes Rafael and Russell too)!

For merging I see two options:
- All through drm-intel, but will only land in 5.2 because the feature
  cut-off has already happened for i915. So a bit awkward.
- Topic branch with the 2 component patches plus the snd-hda/drm-i915
  patch, so that you/Takashi/drm can pull it in as needed. The drm
  component doc patch (3/4 in this series) I can pull in later on.

Greg/Takashi, any preferences?

Thanks, Daniel
On Fri, Feb 8, 2019 at 4:29 PM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> On Fri, Feb 08, 2019 at 12:51:23PM +0100, Greg Kroah-Hartman wrote:
> > On Fri, Feb 08, 2019 at 12:27:56AM +0100, Daniel Vetter wrote:
> > > 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>
> > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> >
> > Thanks for doing this!
> >
> > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> Thanks for reviewing (obviously includes Rafael and Russell too)!
>
> For merging I see two options:
> - All through drm-intel, but will only land in 5.2 because the feature
>   cut-off has already happened for i915. So a bit awkward.
> - Topic branch with the 2 component patches plus the snd-hda/drm-i915
>   patch, so that you/Takashi/drm can pull it in as needed. The drm
>   component doc patch (3/4 in this series) I can pull in later on.
>
> Greg/Takashi, any preferences?

Just realized that for the mei side of this series I need a topic
branch anyway, so topic branch it is. I'll prep that so that CI can
beat on it over the w/e, and we can rebase the i915/mei series on top,
and then send out the topic pull to everyone early next week. You can
then all decide whether you need it or not.

Cheers, Daniel
On 2/7/19 3:27 PM, Daniel Vetter wrote:

Hi Daniel,

I have a few possible changes for this documentation (see below).

> ---
>  Documentation/driver-api/component.rst   |  17 ++++
>  Documentation/driver-api/device_link.rst |   3 +
>  Documentation/driver-api/index.rst       |   1 +
>  drivers/base/component.c                 | 106 ++++++++++++++++++++++-
>  include/linux/component.h                |  70 +++++++++++++++
>  5 files changed, 194 insertions(+), 3 deletions(-)
>  create mode 100644 Documentation/driver-api/component.rst
> 



> diff --git a/drivers/base/component.c b/drivers/base/component.c
> index ddcea8739c12..1624c2a892a5 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

              on various components

> + * 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

                                        components {of | from} 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

                             {of | from}

> + * &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

                                    components

> + * @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;
> diff --git a/include/linux/component.h b/include/linux/component.h
> index e71fbbbc74e2..83da25bdf59c 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 +92,22 @@ 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

                                  component match entry (or item)
?

> + * @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)
> 


cheers.