Hi William What's the status on these? If you are happy that reviews and testing is complete enough, do you want me to take them after I pick up the eqep driver (hopefully shortly dependent on the pull request Greg has from me being fine). Thanks, Jonathan On Sun, 6 Oct 2019 16:03:08 -0400 William Breathitt Gray <vilhelm.gray@xxxxxxxxx> wrote: > Changes in v5: > - Add changes and additions to generic-counter.rst to clarify theory > and use of the Generic Counter interface > - Fix typo in counter.h action_get description comment > > The changes in this patchset will not affect the userspace interface. > Rather, these changes are intended to simplify the kernelspace Counter > callbacks for counter device driver authors. > > The following main changes are proposed: > > * Retire the opaque counter_count_read_value/counter_count_write_value > structures and simply represent count data as an unsigned integer. > > * Retire the opaque counter_signal_read_value structure and represent > Signal data as a counter_signal_value enum. > > These changes should reduce some complexity and code in the use and > implementation of the count_read, count_write, and signal_read > callbacks. > > The opaque structures for Count data and Signal data were introduced > originally in anticipation of supporting various representations of > counter data (e.g. arbitrary-precision tallies, floating-point spherical > coordinate positions, etc). However, with the counter device drivers > that have appeared, it's become apparent that utilizing opaque > structures in kernelspace is not the best approach to take. > > I believe it is best to let userspace applications decide how to > interpret the count data they receive. There are a couple of reasons why > it would be good to do so: > > * Users use their devices in unexpected ways. > > For example, a quadrature encoder counter device is typically used to > keep track of the position of a motor, but a user could set the device > in a pulse-direction mode and instead use it to count sporadic rising > edges from an arbitrary signal line unrelated to positioning. Users > should have the freedom to decide what their data represents. > > * Most counter devices represent data as unsigned integers anyway. > > For example, whether the device is a tally counter or position > counter, the count data is represented to the user as an unsigned > integer value. So specifying that one device is representing tallies > while the other specifies positions does not provide much utility from > an interface perspective. > > For these reasons, the count_read and count_write callbacks have been > redefined to pass count data directly as unsigned long instead of passed > via opaque structures: > > count_read(struct counter_device *counter, > struct counter_count *count, unsigned long *val); > count_write(struct counter_device *counter, > struct counter_count *count, unsigned long val); > > Similarly, the signal_read is redefined to pass Signal data directly as > a counter_signal_value enum instead of via an opaque structure: > > signal_read(struct counter_device *counter, > struct counter_signal *signal, > enum counter_signal_value *val); > > The counter_signal_value enum is simply the counter_signal_level enum > redefined to remove the references to the Signal data "level" data type. > > William Breathitt Gray (3): > counter: Simplify the count_read and count_write callbacks > docs: driver-api: generic-counter: Update Count and Signal data types > counter: Fix typo in action_get description > > Documentation/driver-api/generic-counter.rst | 162 +++++++++++-------- > drivers/counter/104-quad-8.c | 33 ++-- > drivers/counter/counter.c | 101 ++---------- > drivers/counter/ftm-quaddec.c | 14 +- > drivers/counter/stm32-lptimer-cnt.c | 5 +- > drivers/counter/stm32-timer-cnt.c | 17 +- > drivers/counter/ti-eqep.c | 19 +-- > include/linux/counter.h | 76 ++------- > 8 files changed, 144 insertions(+), 283 deletions(-) > > > base-commit: 0c3aa63a842d84990bd02622f2fa50d2bd33c652 > prerequisite-patch-id: ebe284609b3db8d4130ea2915f7f7b185c743a70 > prerequisite-patch-id: cbe857759f10d875690df125d18bc04f585ac7c9 > prerequisite-patch-id: 21f2660dc88627387ee4666d08044c63dd961dae
