[v7,03/10] docs: Add Generic Counter interface documentation

On 06/21/2018 04:07 PM, William Breathitt Gray wrote:

+Userspace Interface
+===================
+
+Several sysfs attributes are generated by the Generic Counter interface,
+and reside under the /sys/bus/counter/devices/counterX directory, where
+counterX refers to the respective counter device. Please see
+Documentation/ABI/testing/sys-bus-counter-generic-sysfs for detailed
+information on each Generic Counter interface sysfs attribute.
+
+Through these sysfs attributes, programs and scripts may interact with
+the Generic Counter paradigm Counts, Signals, and Synapses of respective
+counter devices.
+

Have you considered a character device in addition to the sysfs interface?

I basically have many of the same concerns that resulted in a char dev for
gpio[1].

- With sysfs, you *can* technically poll for events, but then you have to
   seek and read or re-open the file.
- File permissions are annoying if you want a non root user to be able to
   use the device.
- A single program can't claim exclusive access to a device.
- There is no automatic cleanup if a userspace program accessing the device
    crashes.

[1]: https://www.elinux.org/images/7/74/Elce2017_new_GPIO_interface.pdf