What is the use of driver to components?
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 components (scanout engines, blending blocks, transcoders for various outputs and so on). Show The component helper also doesn’t solve runtime dependencies, e.g. for system suspend and resume operations. See also device links. 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(). API¶struct component_ops¶callbacks for component drivers Definition struct component_ops { int (*bind)(struct device *comp, struct device *master, void *master_data); void (*unbind)(struct device *comp, struct device *master, void *master_data); }; Members bindCalled through component_bind_all() when the aggregate driver is ready to bind the overall driver. unbindCalled 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. Description Components are registered with component_add() and unregistered with component_del(). structcomponent_master_ops¶callback for the aggregate driver Definition struct component_master_ops { int (*bind)(struct device *master); void (*unbind)(struct device *master); }; Members bindCalled 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:
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. unbindCalled when either the aggregate driver, using component_master_del(), or one of its components, using component_del(), is unregistered. Description Aggregate drivers are registered with component_master_add_with_match() and unregistered with component_master_del(). void component_match_add(structdevice*parent, structcomponent_match **matchptr, int(*compare)(struct device*,void*), void *compare_data)¶add a component match entry Parameters struct device *parentdevice with the aggregate driver struct component_match **matchptrpointer to the list of component matches int (*compare)(struct device *, void *)compare function to match against all components void *compare_dataopaque pointer passed to the compare function Description Adds a new component match to the list stored in matchptr, which the parent aggregate driver needs to function. The list of component matches pointed to by matchptr must be initialized to NULL before adding the first match. This only matches against components added with component_add(). The allocated match list in matchptr is automatically released using devm actions. See also component_match_add_release() and component_match_add_typed(). intcomponent_compare_of(structdevice *dev, void*data)¶A common component compare function for of_node Parameters struct device *devcomponent device void *datacompare_data from component_match_add_release() Description A common compare function when compare_data is device of_node. e.g. component_match_add_release(masterdev, match, component_release_of, component_compare_of, component_dev_of_node) voidcomponent_release_of(structdevice*dev, void *data)¶A common component release function for of_node Parameters struct device *devcomponent device void *datacompare_data from component_match_add_release() Description About the example, Please see component_compare_of(). int component_compare_dev(structdevice*dev, void *data)¶A common component compare function for dev Parameters struct device *devcomponent device void *datacompare_data from component_match_add_release() Description A common compare function when compare_data is struce device. e.g. component_match_add(masterdev, match, component_compare_dev, component_dev) int component_compare_dev_name(structdevice*dev, void *data)¶A common component compare function for device name Parameters struct device *devcomponent device void *datacompare_data from component_match_add_release() Description A common compare function when compare_data is device name string. e.g. component_match_add(masterdev, match, component_compare_dev_name, “component_dev_name”) void component_match_add_release(structdevice*parent, structcomponent_match **matchptr, void(*release)(struct device*,void*), int (*compare)(structdevice*,void*), void*compare_data)¶add a component match entry with release callback Parameters struct device *parentparent device of the aggregate driver struct component_match **matchptrpointer to the list of component matches void (*release)(struct device *, void *)release function for compare_data int (*compare)(struct device *, void *)compare function to match against all components opaque pointer passed to the compare function Description Adds a new component match to the list stored in matchptr, which the aggregate driver needs to function. The list of component matches pointed to by matchptr must be initialized to NULL before adding the first match. This only matches against components added with component_add(). 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() and component_match_add_typed(). voidcomponent_match_add_typed(struct device*parent, structcomponent_match**matchptr, int (*compare_typed)(structdevice*,int, void*), void*compare_data)¶add a component match entry for a typed component Parameters struct device *parentparent device of the aggregate driver struct component_match **matchptrpointer to the list of component matches int (*compare_typed)(struct device *, int, void *)compare function to match against all typed components void *compare_dataopaque pointer passed to the compare function Description Adds a new component match to the list stored in matchptr, which the aggregate driver needs to function. The list of component matches pointed to by matchptr must be initialized to NULL before adding the first match. This only matches against components added with component_add_typed(). The allocated match list in matchptr is automatically released using devm actions. See also component_match_add_release() and component_match_add_typed(). int component_master_add_with_match(structdevice*parent, conststruct component_master_ops*ops, structcomponent_match *match)¶register an aggregate driver Parameters struct device *parentparent device of the aggregate driver const struct component_master_ops *opscallbacks for the aggregate driver struct component_match *matchcomponent match list for the aggregate driver Description 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(). void component_master_del(structdevice*parent, conststruct component_master_ops*ops)¶unregister an aggregate driver Parameters struct device *parentparent device of the aggregate driver const struct component_master_ops *opscallbacks for the aggregate driver Description 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. voidcomponent_unbind_all(struct device*parent, void*data)¶unbind all components of an aggregate driver Parameters struct device *parentparent device of the aggregate driver void *dataopaque pointer, passed to all components Description Unbinds all components of the aggregate device by passing data to their component_ops.unbind functions. Should be called from component_master_ops.unbind. intcomponent_bind_all(struct device*parent, void*data)¶bind all components of an aggregate driver Parameters struct device *parentparent device of the aggregate driver void *dataopaque pointer, passed to all components Description Binds all components of the aggregate dev by passing data to their component_ops.bind functions. Should be called from component_master_ops.bind. intcomponent_add_typed(struct device*dev, conststructcomponent_ops *ops, intsubcomponent)¶register a component Parameters struct device *devcomponent device const struct component_ops *opscomponent callbacks int subcomponentnonzero identifier for subcomponents Description Register a new component for dev. Functions in ops will be call when the aggregate driver is ready to bind the overall driver by calling component_bind_all(). See also struct component_ops. subcomponent must be nonzero and is used to differentiate between multiple components registerd on the same device dev. These components are match using component_match_add_typed(). The component needs to be unregistered at driver unload/disconnect by calling component_del(). See also component_add(). int component_add(structdevice*dev, conststruct component_ops*ops)¶register a component Parameters struct device *devcomponent device const struct component_ops *opscomponent callbacks Description 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(). See also component_add_typed() for a variant that allows multipled different components on the same device. voidcomponent_del(structdevice*dev, conststructcomponent_ops*ops)¶unregister a component Parameters struct device *devcomponent device const struct component_ops *opscomponent callbacks Description 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. What is a component driver?In electronics, a driver is a circuit or component used to control another circuit or component, such as a high-power transistor, liquid crystal display (LCD), stepper motors, and numerous others.
What is device driver and its uses?A device driver is a particular form of software application that allows one hardware device (such as a personal computer) to interact with another hardware device (such as a printer). A device driver may also be called a software driver.
What computer components are needed for drivers?What hardware device drivers should be updated?. BIOS updates.. CD or DVD drive drivers and firmware.. Controllers.. Display drivers.. Keyboard drivers.. Mouse drivers.. Modem drivers.. Motherboard drivers, firmware, and updates.. |