counter: Introduce the Generic Counter interface

2019-04-25T19:33:37Z

This patch introduces the Generic Counter interface for supporting counter devices. In the context of the Generic Counter interface, a counter is defined as a device that reports one or more "counts" based on the state changes of one or more "signals" as evaluated by a defined "count function." Driver callbacks should be provided to communicate with the device: to read and write various Signals and Counts, and to set and get the "action mode" and "count function" for various Synapses and Counts respectively. To support a counter device, a driver must first allocate the available Counter Signals via counter_signal structures. These Signals should be stored as an array and set to the signals array member of an allocated counter_device structure before the Counter is registered to the system. Counter Counts may be allocated via counter_count structures, and respective Counter Signal associations (Synapses) made via counter_synapse structures. Associated counter_synapse structures are stored as an array and set to the the synapses array member of the respective counter_count structure. These counter_count structures are set to the counts array member of an allocated counter_device structure before the Counter is registered to the system. A counter device is registered to the system by passing the respective initialized counter_device structure to the counter_register function; similarly, the counter_unregister function unregisters the respective Counter. The devm_counter_register and devm_counter_unregister functions serve as device memory-managed versions of the counter_register and counter_unregister functions respectively. Reviewed-by: Jonathan Cameron Signed-off-by: William Breathitt Gray Signed-off-by: Greg Kroah-Hartman

user/sven/linux.git/include/linux/counter.h, branch v5.4.55

counter: Introduce the Generic Counter interface