From 4a4cfe3836916e12282ceb5c4bdd799dc71af567 Mon Sep 17 00:00:00 2001 From: Tony Breeds Date: Sat, 22 Sep 2007 07:35:52 +1000 Subject: [POWERPC] Implement generic time of day clocksource for powerpc Signed-off-by: Tony Breeds Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/time.c | 270 ++++++++++++++++----------------------------- 1 file changed, 98 insertions(+), 172 deletions(-) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index b94e4dffba1..e71a0d8c597 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -65,17 +65,44 @@ #include #include #include -#ifdef CONFIG_PPC64 #include -#endif #ifdef CONFIG_PPC_ISERIES #include #include #endif +/* powerpc clocksource/clockevent code */ + +#include + +static cycle_t rtc_read(void); +static struct clocksource clocksource_rtc = { + .name = "rtc", + .rating = 400, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .mask = CLOCKSOURCE_MASK(64), + .shift = 22, + .mult = 0, /* To be filled in */ + .read = rtc_read, +}; + +static cycle_t timebase_read(void); +static struct clocksource clocksource_timebase = { + .name = "timebase", + .rating = 400, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .mask = CLOCKSOURCE_MASK(64), + .shift = 22, + .mult = 0, /* To be filled in */ + .read = timebase_read, +}; + #ifdef CONFIG_PPC_ISERIES static unsigned long __initdata iSeries_recal_titan; static signed long __initdata iSeries_recal_tb; + +/* Forward declaration is only needed for iSereis compiles */ +void __init clocksource_init(void); #endif #define XSEC_PER_SEC (1024*1024) @@ -343,65 +370,6 @@ void udelay(unsigned long usecs) } EXPORT_SYMBOL(udelay); -/* - * This version of gettimeofday has microsecond resolution. - */ -static inline void __do_gettimeofday(struct timeval *tv) -{ - unsigned long sec, usec; - u64 tb_ticks, xsec; - struct gettimeofday_vars *temp_varp; - u64 temp_tb_to_xs, temp_stamp_xsec; - - /* - * These calculations are faster (gets rid of divides) - * if done in units of 1/2^20 rather than microseconds. - * The conversion to microseconds at the end is done - * without a divide (and in fact, without a multiply) - */ - temp_varp = do_gtod.varp; - - /* Sampling the time base must be done after loading - * do_gtod.varp in order to avoid racing with update_gtod. - */ - data_barrier(temp_varp); - tb_ticks = get_tb() - temp_varp->tb_orig_stamp; - temp_tb_to_xs = temp_varp->tb_to_xs; - temp_stamp_xsec = temp_varp->stamp_xsec; - xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs); - sec = xsec / XSEC_PER_SEC; - usec = (unsigned long)xsec & (XSEC_PER_SEC - 1); - usec = SCALE_XSEC(usec, 1000000); - - tv->tv_sec = sec; - tv->tv_usec = usec; -} - -void do_gettimeofday(struct timeval *tv) -{ - if (__USE_RTC()) { - /* do this the old way */ - unsigned long flags, seq; - unsigned int sec, nsec, usec; - - do { - seq = read_seqbegin_irqsave(&xtime_lock, flags); - sec = xtime.tv_sec; - nsec = xtime.tv_nsec + tb_ticks_since(tb_last_jiffy); - } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); - usec = nsec / 1000; - while (usec >= 1000000) { - usec -= 1000000; - ++sec; - } - tv->tv_sec = sec; - tv->tv_usec = usec; - return; - } - __do_gettimeofday(tv); -} - -EXPORT_SYMBOL(do_gettimeofday); /* * There are two copies of tb_to_xs and stamp_xsec so that no @@ -447,56 +415,6 @@ static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec, ++(vdso_data->tb_update_count); } -/* - * When the timebase - tb_orig_stamp gets too big, we do a manipulation - * between tb_orig_stamp and stamp_xsec. The goal here is to keep the - * difference tb - tb_orig_stamp small enough to always fit inside a - * 32 bits number. This is a requirement of our fast 32 bits userland - * implementation in the vdso. If we "miss" a call to this function - * (interrupt latency, CPU locked in a spinlock, ...) and we end up - * with a too big difference, then the vdso will fallback to calling - * the syscall - */ -static __inline__ void timer_recalc_offset(u64 cur_tb) -{ - unsigned long offset; - u64 new_stamp_xsec; - u64 tlen, t2x; - u64 tb, xsec_old, xsec_new; - struct gettimeofday_vars *varp; - - if (__USE_RTC()) - return; - tlen = current_tick_length(); - offset = cur_tb - do_gtod.varp->tb_orig_stamp; - if (tlen == last_tick_len && offset < 0x80000000u) - return; - if (tlen != last_tick_len) { - t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs); - last_tick_len = tlen; - } else - t2x = do_gtod.varp->tb_to_xs; - new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC; - do_div(new_stamp_xsec, 1000000000); - new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC; - - ++vdso_data->tb_update_count; - smp_mb(); - - /* - * Make sure time doesn't go backwards for userspace gettimeofday. - */ - tb = get_tb(); - varp = do_gtod.varp; - xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs) - + varp->stamp_xsec; - xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec; - if (xsec_new < xsec_old) - new_stamp_xsec += xsec_old - xsec_new; - - update_gtod(cur_tb, new_stamp_xsec, t2x); -} - #ifdef CONFIG_SMP unsigned long profile_pc(struct pt_regs *regs) { @@ -568,6 +486,8 @@ static int __init iSeries_tb_recal(void) iSeries_recal_titan = titan; iSeries_recal_tb = tb; + /* Called here as now we know accurate values for the timebase */ + clocksource_init(); return 0; } late_initcall(iSeries_tb_recal); @@ -650,7 +570,6 @@ void timer_interrupt(struct pt_regs * regs) if (per_cpu(last_jiffy, cpu) >= tb_next_jiffy) { tb_last_jiffy = tb_next_jiffy; do_timer(1); - timer_recalc_offset(tb_last_jiffy); } write_sequnlock(&xtime_lock); } @@ -722,66 +641,6 @@ unsigned long long sched_clock(void) return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift; } -int do_settimeofday(struct timespec *tv) -{ - time_t wtm_sec, new_sec = tv->tv_sec; - long wtm_nsec, new_nsec = tv->tv_nsec; - unsigned long flags; - u64 new_xsec; - unsigned long tb_delta; - - if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) - return -EINVAL; - - write_seqlock_irqsave(&xtime_lock, flags); - - /* - * Updating the RTC is not the job of this code. If the time is - * stepped under NTP, the RTC will be updated after STA_UNSYNC - * is cleared. Tools like clock/hwclock either copy the RTC - * to the system time, in which case there is no point in writing - * to the RTC again, or write to the RTC but then they don't call - * settimeofday to perform this operation. - */ - - /* Make userspace gettimeofday spin until we're done. */ - ++vdso_data->tb_update_count; - smp_mb(); - - /* - * Subtract off the number of nanoseconds since the - * beginning of the last tick. - */ - tb_delta = tb_ticks_since(tb_last_jiffy); - tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */ - new_nsec -= SCALE_XSEC(tb_delta, 1000000000); - - wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec); - wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec); - - set_normalized_timespec(&xtime, new_sec, new_nsec); - set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); - - ntp_clear(); - - new_xsec = xtime.tv_nsec; - if (new_xsec != 0) { - new_xsec *= XSEC_PER_SEC; - do_div(new_xsec, NSEC_PER_SEC); - } - new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC; - update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs); - - vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; - vdso_data->tz_dsttime = sys_tz.tz_dsttime; - - write_sequnlock_irqrestore(&xtime_lock, flags); - clock_was_set(); - return 0; -} - -EXPORT_SYMBOL(do_settimeofday); - static int __init get_freq(char *name, int cells, unsigned long *val) { struct device_node *cpu; @@ -873,6 +732,69 @@ unsigned long read_persistent_clock(void) tm.tm_hour, tm.tm_min, tm.tm_sec); } +/* clocksource code */ +static cycle_t rtc_read(void) +{ + return (cycle_t)get_rtc(); +} + +static cycle_t timebase_read(void) +{ + return (cycle_t)get_tb(); +} + +void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) +{ + u64 t2x, stamp_xsec; + + if (clock != &clocksource_timebase) + return; + + /* Make userspace gettimeofday spin until we're done. */ + ++vdso_data->tb_update_count; + smp_mb(); + + /* XXX this assumes clock->shift == 22 */ + /* 4611686018 ~= 2^(20+64-22) / 1e9 */ + t2x = (u64) clock->mult * 4611686018ULL; + stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC; + do_div(stamp_xsec, 1000000000); + stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC; + update_gtod(clock->cycle_last, stamp_xsec, t2x); +} + +void update_vsyscall_tz(void) +{ + /* Make userspace gettimeofday spin until we're done. */ + ++vdso_data->tb_update_count; + smp_mb(); + vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; + vdso_data->tz_dsttime = sys_tz.tz_dsttime; + smp_mb(); + ++vdso_data->tb_update_count; +} + +void __init clocksource_init(void) +{ + struct clocksource *clock; + + if (__USE_RTC()) + clock = &clocksource_rtc; + else + clock = &clocksource_timebase; + + clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift); + + if (clocksource_register(clock)) { + printk(KERN_ERR "clocksource: %s is already registered\n", + clock->name); + return; + } + + printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n", + clock->name, clock->mult, clock->shift); +} + /* This function is only called on the boot processor */ void __init time_init(void) { @@ -982,6 +904,10 @@ void __init time_init(void) write_sequnlock_irqrestore(&xtime_lock, flags); + /* Register the clocksource, if we're not running on iSeries */ + if (!firmware_has_feature(FW_FEATURE_ISERIES)) + clocksource_init(); + /* Not exact, but the timer interrupt takes care of this */ set_dec(tb_ticks_per_jiffy); } -- cgit v1.2.3-70-g09d2