diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/tile/kernel/time.c | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/arch/tile/kernel/time.c b/arch/tile/kernel/time.c index b9ab25a889b..6bed820e142 100644 --- a/arch/tile/kernel/time.c +++ b/arch/tile/kernel/time.c @@ -36,16 +36,6 @@ /* How many cycles per second we are running at. */ static cycles_t cycles_per_sec __write_once; -/* - * We set up shift and multiply values with a minsec of five seconds, - * since our timer counter counts down 31 bits at a frequency of - * no less than 500 MHz. See @minsec for clocks_calc_mult_shift(). - * We could use a different value for the 64-bit free-running - * cycle counter, but we use the same one for consistency, and since - * we will be reasonably precise with this value anyway. - */ -#define TILE_MINSEC 5 - cycles_t get_clock_rate(void) { return cycles_per_sec; @@ -68,6 +58,14 @@ cycles_t get_cycles(void) } #endif +/* + * We use a relatively small shift value so that sched_clock() + * won't wrap around very often. + */ +#define SCHED_CLOCK_SHIFT 10 + +static unsigned long sched_clock_mult __write_once; + static cycles_t clocksource_get_cycles(struct clocksource *cs) { return get_cycles(); @@ -78,6 +76,7 @@ static struct clocksource cycle_counter_cs = { .rating = 300, .read = clocksource_get_cycles, .mask = CLOCKSOURCE_MASK(64), + .shift = 22, /* typical value, e.g. x86 tsc uses this */ .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; @@ -88,8 +87,10 @@ static struct clocksource cycle_counter_cs = { void __init setup_clock(void) { cycles_per_sec = hv_sysconf(HV_SYSCONF_CPU_SPEED); - clocksource_calc_mult_shift(&cycle_counter_cs, cycles_per_sec, - TILE_MINSEC); + sched_clock_mult = + clocksource_hz2mult(cycles_per_sec, SCHED_CLOCK_SHIFT); + cycle_counter_cs.mult = + clocksource_hz2mult(cycles_per_sec, cycle_counter_cs.shift); } void __init calibrate_delay(void) @@ -117,9 +118,14 @@ void __init time_init(void) * counter, plus bit 31, which signifies that the counter has wrapped * from zero to (2**31) - 1. The INT_TILE_TIMER interrupt will be * raised as long as bit 31 is set. + * + * The TILE_MINSEC value represents the largest range of real-time + * we can possibly cover with the timer, based on MAX_TICK combined + * with the slowest reasonable clock rate we might run at. */ #define MAX_TICK 0x7fffffff /* we have 31 bits of countdown timer */ +#define TILE_MINSEC 5 /* timer covers no more than 5 seconds */ static int tile_timer_set_next_event(unsigned long ticks, struct clock_event_device *evt) @@ -211,8 +217,7 @@ void do_timer_interrupt(struct pt_regs *regs, int fault_num) unsigned long long sched_clock(void) { return clocksource_cyc2ns(get_cycles(), - cycle_counter_cs.mult, - cycle_counter_cs.shift); + sched_clock_mult, SCHED_CLOCK_SHIFT); } int setup_profiling_timer(unsigned int multiplier) |