Messages in this thread | | | Date | Sun, 31 Aug 2014 18:46:12 +0200 | From | Oleksij Rempel <> | Subject | Writing clocksource driver, tips? |
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Hello all,
currently i work on porting linux to Aplscale ASM9260, most basic parts are done, now is the time for clocksource driver. I never did it before, so i need some beginner tips. My current driver clocksource provide periodic events at 100Hz rate. But this hardvare can do more then it. This SoC has 4 32bit-timer controller attached to 100MHz source. Each controller has 4 separate timer register each of them can be configure separately for scale, match and interrupt. 3 controllers can choice the tick source. This controller looks similar to one found on NXP LPC1311, but looks like no similar hardware in drivers/clocksource.
For now i have fallowing questions: - 1 timer can be used for clocksource other as clock_event_device, how can i use other 2 timers on same controller. and how can i use other 3 controllers? - theoretically i can use clocksource_mmio_init to read directly timer_counter_register. Which scale should be used on it. 100MHz is probably too match. - should clocksource provide interrupt on overflow or some kind of limit?
-- Regards, Oleksij
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