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.*/- /**
* @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.*/}; @@ -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.*/- /**
* @unbind:** Called when either the aggregate driver, using* component_master_del(), or one of its components, using* component_del(), is unregistered.*/};
@@ -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.