On Thursday 15 May 2014 15:56:03 Michal Simek wrote: > IP is configurable as is normal for us. > You can select IP with just one timer. > It means register locations for specific timer are fixed. > http://www.xilinx.com/support/documentation/ip_documentation/xps_timer.pdf > > timer0 - offset 0x0 > timer1 - offset 0x10 (doesn't need to be synthesized) > > There is one interrupt for both timers. > > Timers can be as timers (up/down count/ reload with or without IRQs) > But then one options is to use both timers and generate PWM signal. > From full ip description in DT you can see xlnx,gen0-assert = <1>; > which can suggest that this IP can output PMW signal. > (We can also detect if PWM0 signal is connected just to be sure > that PWM can be enabled). > > There is also capture trigger mode where external signal start/stop > timer counting. > > It means there are 3 modes - timer, capture and PWM. > Timer (clocksource, clockevent) requires specific handling, > PWM has own subsystem and not sure if there is any subsystem for > capture mode. Is there any? I don't think so. Possibly somewhere in IIO. > Not every timer configuration is suitable for all things > but fully configured timer can be used in all 3 modes. > > > I think that make sense to register and map all timers in the system > and classify them with flags (like can't be used for capture or PMW > if there are not outputs connected) and then use the best > timer for clocksource and clockevent. The best candidate is IP > with the lowest IRQ number in dual timer mode but in general > whatever timer can be used that's why we can't probably avoid > timer specification in DT. > In spite of this smells because you are saying via DT > to Linux which timer should be used for what purpose. We had discussions about this in the past, but I don't remember the outcome of that. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
