[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
Series "Series without cover letter"
Commit 4d69c80e0d0fd8cf12d985841eb0fce5c29819ad
Headers show

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

Greg Kroah-Hartman Feb. 8, 2019, 11:51 a.m.
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>
Daniel Vetter Feb. 8, 2019, 3:29 p.m.
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
Daniel Vetter Feb. 8, 2019, 3:45 p.m.
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
Randy Dunlap Feb. 18, 2019, 3:31 a.m.
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.