diff options
Diffstat (limited to 'arch/powerpc/kernel/time.c')
| -rw-r--r-- | arch/powerpc/kernel/time.c | 96 |
1 files changed, 71 insertions, 25 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index 2b33cfa..fe6f3a2 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -59,10 +59,10 @@ #include <linux/suspend.h> #include <linux/rtc.h> #include <linux/sched/cputime.h> +#include <linux/processor.h> #include <asm/trace.h> #include <asm/io.h> -#include <asm/processor.h> #include <asm/nvram.h> #include <asm/cache.h> #include <asm/machdep.h> @@ -442,6 +442,7 @@ void __delay(unsigned long loops) unsigned long start; int diff; + spin_begin(); if (__USE_RTC()) { start = get_rtcl(); do { @@ -449,13 +450,14 @@ void __delay(unsigned long loops) diff = get_rtcl() - start; if (diff < 0) diff += 1000000000; + spin_cpu_relax(); } while (diff < loops); } else { start = get_tbl(); while (get_tbl() - start < loops) - HMT_low(); - HMT_medium(); + spin_cpu_relax(); } + spin_end(); } EXPORT_SYMBOL(__delay); @@ -675,7 +677,7 @@ EXPORT_SYMBOL_GPL(tb_to_ns); * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b * are 64-bit unsigned numbers. */ -unsigned long long sched_clock(void) +notrace unsigned long long sched_clock(void) { if (__USE_RTC()) return get_rtc(); @@ -739,12 +741,20 @@ static int __init get_freq(char *name, int cells, unsigned long *val) static void start_cpu_decrementer(void) { #if defined(CONFIG_BOOKE) || defined(CONFIG_40x) + unsigned int tcr; + /* Clear any pending timer interrupts */ mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS); - /* Enable decrementer interrupt */ - mtspr(SPRN_TCR, TCR_DIE); -#endif /* defined(CONFIG_BOOKE) || defined(CONFIG_40x) */ + tcr = mfspr(SPRN_TCR); + /* + * The watchdog may have already been enabled by u-boot. So leave + * TRC[WP] (Watchdog Period) alone. + */ + tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */ + tcr |= TCR_DIE; /* Enable decrementer */ + mtspr(SPRN_TCR, tcr); +#endif } void __init generic_calibrate_decr(void) @@ -823,38 +833,76 @@ void read_persistent_clock(struct timespec *ts) } /* clocksource code */ -static u64 rtc_read(struct clocksource *cs) +static notrace u64 rtc_read(struct clocksource *cs) { return (u64)get_rtc(); } -static u64 timebase_read(struct clocksource *cs) +static notrace u64 timebase_read(struct clocksource *cs) { return (u64)get_tb(); } -void update_vsyscall_old(struct timespec *wall_time, struct timespec *wtm, - struct clocksource *clock, u32 mult, u64 cycle_last) + +void update_vsyscall(struct timekeeper *tk) { + struct timespec xt; + struct clocksource *clock = tk->tkr_mono.clock; + u32 mult = tk->tkr_mono.mult; + u32 shift = tk->tkr_mono.shift; + u64 cycle_last = tk->tkr_mono.cycle_last; u64 new_tb_to_xs, new_stamp_xsec; - u32 frac_sec; + u64 frac_sec; if (clock != &clocksource_timebase) return; + xt.tv_sec = tk->xtime_sec; + xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift); + /* Make userspace gettimeofday spin until we're done. */ ++vdso_data->tb_update_count; smp_mb(); - /* 19342813113834067 ~= 2^(20+64) / 1e9 */ - new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift); - new_stamp_xsec = (u64) wall_time->tv_nsec * XSEC_PER_SEC; - do_div(new_stamp_xsec, 1000000000); - new_stamp_xsec += (u64) wall_time->tv_sec * XSEC_PER_SEC; + /* + * This computes ((2^20 / 1e9) * mult) >> shift as a + * 0.64 fixed-point fraction. + * The computation in the else clause below won't overflow + * (as long as the timebase frequency is >= 1.049 MHz) + * but loses precision because we lose the low bits of the constant + * in the shift. Note that 19342813113834067 ~= 2^(20+64) / 1e9. + * For a shift of 24 the error is about 0.5e-9, or about 0.5ns + * over a second. (Shift values are usually 22, 23 or 24.) + * For high frequency clocks such as the 512MHz timebase clock + * on POWER[6789], the mult value is small (e.g. 32768000) + * and so we can shift the constant by 16 initially + * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the + * remaining shifts after the multiplication, which gives a + * more accurate result (e.g. with mult = 32768000, shift = 24, + * the error is only about 1.2e-12, or 0.7ns over 10 minutes). + */ + if (mult <= 62500000 && clock->shift >= 16) + new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16); + else + new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift); + + /* + * Compute the fractional second in units of 2^-32 seconds. + * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift + * in nanoseconds, so multiplying that by 2^32 / 1e9 gives + * it in units of 2^-32 seconds. + * We assume shift <= 32 because clocks_calc_mult_shift() + * generates shift values in the range 0 - 32. + */ + frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift); + do_div(frac_sec, NSEC_PER_SEC); - BUG_ON(wall_time->tv_nsec >= NSEC_PER_SEC); - /* this is tv_nsec / 1e9 as a 0.32 fraction */ - frac_sec = ((u64) wall_time->tv_nsec * 18446744073ULL) >> 32; + /* + * Work out new stamp_xsec value for any legacy users of systemcfg. + * stamp_xsec is in units of 2^-20 seconds. + */ + new_stamp_xsec = frac_sec >> 12; + new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC; /* * tb_update_count is used to allow the userspace gettimeofday code @@ -864,15 +912,13 @@ void update_vsyscall_old(struct timespec *wall_time, struct timespec *wtm, * the two values of tb_update_count match and are even then the * tb_to_xs and stamp_xsec values are consistent. If not, then it * loops back and reads them again until this criteria is met. - * We expect the caller to have done the first increment of - * vdso_data->tb_update_count already. */ vdso_data->tb_orig_stamp = cycle_last; vdso_data->stamp_xsec = new_stamp_xsec; vdso_data->tb_to_xs = new_tb_to_xs; - vdso_data->wtom_clock_sec = wtm->tv_sec; - vdso_data->wtom_clock_nsec = wtm->tv_nsec; - vdso_data->stamp_xtime = *wall_time; + vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec; + vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec; + vdso_data->stamp_xtime = xt; vdso_data->stamp_sec_fraction = frac_sec; smp_wmb(); ++(vdso_data->tb_update_count); |
