On Tue, Aug 05, 2003 at 05:38:40PM +0400, Dmitry Antipov wrote: > Hello all, > > I'm working with IT8172-based MIPS board and want to use one of (or may > be both) on-board timers. > For my purposes, it's required to generate irq from timer rarely, for > example, each 1 sec, or each 5 sec > or so. (The usage of Linux timer interface (init_timer() etc...) is > forbidden Using linux timer seems perfect for the need. Why not? For an example of using timer you can take a look of my real time test suite http://linux.junsun.net/preemp-test/ > , and I don't want to touch > system timer to avoid the potential damage for basic timekeeping, > scheduling, etc.). I have two problems: > - timer backward counter is 16-bit wide and reaches zero too fast, even > starting from 0xffff; > - timer input clock may be one of CPU clock, CPU clock /4, CPU clock/8 > or CPU clock /16, which looks > very fast too > So, the minimum interrupt frequency from both timers is 96 ints/HZ (with > TCR0.PST0 is 0 and > TCVR0 is 0xffff) and the maximum is around 150000 ints/HZ. Even the > minimum is too large for me... > You can write a driver that "accumlates" the interrupts until a desired duration is reached before it actually does anything useful. Jun
