diff options
Diffstat (limited to 'arch/alpha/kernel/time.c')
| -rw-r--r-- | arch/alpha/kernel/time.c | 69 |
1 files changed, 31 insertions, 38 deletions
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c index 5465e93..1efbed8 100644 --- a/arch/alpha/kernel/time.c +++ b/arch/alpha/kernel/time.c @@ -51,6 +51,7 @@ #include <linux/mc146818rtc.h> #include <linux/time.h> #include <linux/timex.h> +#include <linux/clocksource.h> #include "proto.h" #include "irq_impl.h" @@ -332,6 +333,34 @@ rpcc_after_update_in_progress(void) return rpcc(); } +#ifndef CONFIG_SMP +/* Until and unless we figure out how to get cpu cycle counters + in sync and keep them there, we can't use the rpcc. */ +static cycle_t read_rpcc(struct clocksource *cs) +{ + cycle_t ret = (cycle_t)rpcc(); + return ret; +} + +static struct clocksource clocksource_rpcc = { + .name = "rpcc", + .rating = 300, + .read = read_rpcc, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS +}; + +static inline void register_rpcc_clocksource(long cycle_freq) +{ + clocksource_calc_mult_shift(&clocksource_rpcc, cycle_freq, 4); + clocksource_register(&clocksource_rpcc); +} +#else /* !CONFIG_SMP */ +static inline void register_rpcc_clocksource(long cycle_freq) +{ +} +#endif /* !CONFIG_SMP */ + void __init time_init(void) { @@ -385,6 +414,8 @@ time_init(void) __you_loose(); } + register_rpcc_clocksource(cycle_freq); + state.last_time = cc1; state.scaled_ticks_per_cycle = ((unsigned long) HZ << FIX_SHIFT) / cycle_freq; @@ -395,44 +426,6 @@ time_init(void) } /* - * Use the cycle counter to estimate an displacement from the last time - * tick. Unfortunately the Alpha designers made only the low 32-bits of - * the cycle counter active, so we overflow on 8.2 seconds on a 500MHz - * part. So we can't do the "find absolute time in terms of cycles" thing - * that the other ports do. - */ -u32 arch_gettimeoffset(void) -{ -#ifdef CONFIG_SMP - /* Until and unless we figure out how to get cpu cycle counters - in sync and keep them there, we can't use the rpcc tricks. */ - return 0; -#else - unsigned long delta_cycles, delta_usec, partial_tick; - - delta_cycles = rpcc() - state.last_time; - partial_tick = state.partial_tick; - /* - * usec = cycles * ticks_per_cycle * 2**48 * 1e6 / (2**48 * ticks) - * = cycles * (s_t_p_c) * 1e6 / (2**48 * ticks) - * = cycles * (s_t_p_c) * 15625 / (2**42 * ticks) - * - * which, given a 600MHz cycle and a 1024Hz tick, has a - * dynamic range of about 1.7e17, which is less than the - * 1.8e19 in an unsigned long, so we are safe from overflow. - * - * Round, but with .5 up always, since .5 to even is harder - * with no clear gain. - */ - - delta_usec = (delta_cycles * state.scaled_ticks_per_cycle - + partial_tick) * 15625; - delta_usec = ((delta_usec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2; - return delta_usec * 1000; -#endif -} - -/* * In order to set the CMOS clock precisely, set_rtc_mmss has to be * called 500 ms after the second nowtime has started, because when * nowtime is written into the registers of the CMOS clock, it will |
