From 60dbd6633178a8625ed71329da0167c6d50c559c Mon Sep 17 00:00:00 2001 From: Jesper Nilsson Date: Fri, 30 Jul 2010 17:33:07 +0200 Subject: CRIS: GENERIC_TIME fixes GENERIC_TIME was not functional for CRIS, giving random backward time jumps. For CRISv32 implement a new clocksource using the free running counter and ditch the arch_gettimeoffset. The random time jumps still existed, but turned out to be the write_seqlock which was missing around our do_timer() call. So switch over to GENERIC_TIME using the clocksource for CRISv32. CRISv10 doesn't have the free running counter needed for the clocksource trick, but we can still use GENERIC_TIME with arch_gettimeoffset. Unfortunately, there were problems in using the prescaler register to timer0 for the gettimeoffset calculation, so it is now ignored, making our resolution worse by the tune of 40usec (0.4%) worst case. At the same time, clean up some formatting and use NSEC_PER_SEC instead of 1000000000. Signed-off-by: Jesper Nilsson --- arch/cris/Kconfig | 5 ++- arch/cris/arch-v10/kernel/time.c | 54 +------------------------ arch/cris/arch-v32/kernel/time.c | 85 ++++++++++++++++------------------------ arch/cris/kernel/time.c | 7 +++- 4 files changed, 45 insertions(+), 106 deletions(-) (limited to 'arch') diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig index e25bf4440b51..4827c72b9634 100644 --- a/arch/cris/Kconfig +++ b/arch/cris/Kconfig @@ -27,7 +27,7 @@ config GENERIC_CMOS_UPDATE def_bool y config ARCH_USES_GETTIMEOFFSET - def_bool y + def_bool n config GENERIC_IOMAP bool @@ -131,16 +131,19 @@ choice config ETRAX100LX bool "ETRAX-100LX-v1" + select ARCH_USES_GETTIMEOFFSET help Support version 1 of the ETRAX 100LX. config ETRAX100LX_V2 bool "ETRAX-100LX-v2" + select ARCH_USES_GETTIMEOFFSET help Support version 2 of the ETRAX 100LX. config SVINTO_SIM bool "ETRAX-100LX-for-xsim-simulator" + select ARCH_USES_GETTIMEOFFSET help Support the xsim ETRAX Simulator. diff --git a/arch/cris/arch-v10/kernel/time.c b/arch/cris/arch-v10/kernel/time.c index 30adae594aef..00eb36f8debf 100644 --- a/arch/cris/arch-v10/kernel/time.c +++ b/arch/cris/arch-v10/kernel/time.c @@ -61,66 +61,16 @@ unsigned long get_ns_in_jiffie(void) unsigned long do_slow_gettimeoffset(void) { - unsigned long count, t1; - unsigned long usec_count = 0; - unsigned short presc_count; - - static unsigned long count_p = TIMER0_DIV;/* for the first call after boot */ - static unsigned long jiffies_p = 0; - - /* - * cache volatile jiffies temporarily; we have IRQs turned off. - */ - unsigned long jiffies_t; + unsigned long count; /* The timer interrupt comes from Etrax timer 0. In order to get * better precision, we check the current value. It might have * underflowed already though. */ - -#ifndef CONFIG_SVINTO_SIM - /* Not available in the xsim simulator. */ count = *R_TIMER0_DATA; - presc_count = *R_TIM_PRESC_STATUS; - /* presc_count might be wrapped */ - t1 = *R_TIMER0_DATA; - if (count != t1){ - /* it wrapped, read prescaler again... */ - presc_count = *R_TIM_PRESC_STATUS; - count = t1; - } -#else - count = 0; - presc_count = 0; -#endif - - jiffies_t = jiffies; - /* - * avoiding timer inconsistencies (they are rare, but they happen)... - * there are one problem that must be avoided here: - * 1. the timer counter underflows - */ - if( jiffies_t == jiffies_p ) { - if( count > count_p ) { - /* Timer wrapped, use new count and prescale - * increase the time corresponding to one jiffie - */ - usec_count = 1000000/HZ; - } - } else - jiffies_p = jiffies_t; - count_p = count; - if (presc_count >= PRESCALE_VALUE/2 ){ - presc_count = PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2; - } else { - presc_count = PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2; - } /* Convert timer value to usec */ - usec_count += ( (TIMER0_DIV - count) * (1000000/HZ)/TIMER0_DIV ) + - (( (presc_count) * (1000000000/PRESCALE_FREQ))/1000); - - return usec_count; + return (TIMER0_DIV - count) * ((NSEC_PER_SEC/1000)/HZ)/TIMER0_DIV; } /* Excerpt from the Etrax100 HSDD about the built-in watchdog: diff --git a/arch/cris/arch-v32/kernel/time.c b/arch/cris/arch-v32/kernel/time.c index 1ee0e1010228..a545211e999d 100644 --- a/arch/cris/arch-v32/kernel/time.c +++ b/arch/cris/arch-v32/kernel/time.c @@ -1,13 +1,13 @@ /* * linux/arch/cris/arch-v32/kernel/time.c * - * Copyright (C) 2003-2007 Axis Communications AB + * Copyright (C) 2003-2010 Axis Communications AB * */ #include #include -#include +#include #include #include #include @@ -36,6 +36,30 @@ /* Number of 763 counts before watchdog bites */ #define ETRAX_WD_CNT ((2*ETRAX_WD_HZ)/HZ + 1) +/* Register the continuos readonly timer available in FS and ARTPEC-3. */ +static cycle_t read_cont_rotime(struct clocksource *cs) +{ + return (u32)REG_RD(timer, regi_timer0, r_time); +} + +static struct clocksource cont_rotime = { + .name = "crisv32_rotime", + .rating = 300, + .read = read_cont_rotime, + .mask = CLOCKSOURCE_MASK(32), + .shift = 10, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int __init etrax_init_cont_rotime(void) +{ + cont_rotime.mult = clocksource_khz2mult(100000, cont_rotime.shift); + clocksource_register(&cont_rotime); + return 0; +} +arch_initcall(etrax_init_cont_rotime); + + unsigned long timer_regs[NR_CPUS] = { regi_timer0, @@ -67,43 +91,6 @@ unsigned long get_ns_in_jiffie(void) return ns; } -unsigned long do_slow_gettimeoffset(void) -{ - unsigned long count; - unsigned long usec_count = 0; - - /* For the first call after boot */ - static unsigned long count_p = TIMER0_DIV; - static unsigned long jiffies_p = 0; - - /* Cache volatile jiffies temporarily; we have IRQs turned off. */ - unsigned long jiffies_t; - - /* The timer interrupt comes from Etrax timer 0. In order to get - * better precision, we check the current value. It might have - * underflowed already though. */ - count = REG_RD(timer, regi_timer0, r_tmr0_data); - jiffies_t = jiffies; - - /* Avoiding timer inconsistencies (they are rare, but they happen) - * There is one problem that must be avoided here: - * 1. the timer counter underflows - */ - if( jiffies_t == jiffies_p ) { - if( count > count_p ) { - /* Timer wrapped, use new count and prescale. - * Increase the time corresponding to one jiffy. - */ - usec_count = 1000000/HZ; - } - } else - jiffies_p = jiffies_t; - count_p = count; - /* Convert timer value to usec */ - /* 100 MHz timer, divide by 100 to get usec */ - usec_count += (TIMER0_DIV - count) / 100; - return usec_count; -} /* From timer MDS describing the hardware watchdog: * 4.3.1 Watchdog Operation @@ -126,8 +113,7 @@ static short int watchdog_key = 42; /* arbitrary 7 bit number */ * is used though, so set this really low. */ #define WATCHDOG_MIN_FREE_PAGES 8 -void -reset_watchdog(void) +void reset_watchdog(void) { #if defined(CONFIG_ETRAX_WATCHDOG) reg_timer_rw_wd_ctrl wd_ctrl = { 0 }; @@ -147,8 +133,7 @@ reset_watchdog(void) /* stop the watchdog - we still need the correct key */ -void -stop_watchdog(void) +void stop_watchdog(void) { #if defined(CONFIG_ETRAX_WATCHDOG) reg_timer_rw_wd_ctrl wd_ctrl = { 0 }; @@ -162,8 +147,7 @@ stop_watchdog(void) extern void show_registers(struct pt_regs *regs); -void -handle_watchdog_bite(struct pt_regs* regs) +void handle_watchdog_bite(struct pt_regs *regs) { #if defined(CONFIG_ETRAX_WATCHDOG) extern int cause_of_death; @@ -203,8 +187,7 @@ handle_watchdog_bite(struct pt_regs* regs) */ extern void cris_do_profile(struct pt_regs *regs); -static inline irqreturn_t -timer_interrupt(int irq, void *dev_id) +static inline irqreturn_t timer_interrupt(int irq, void *dev_id) { struct pt_regs *regs = get_irq_regs(); int cpu = smp_processor_id(); @@ -233,7 +216,9 @@ timer_interrupt(int irq, void *dev_id) return IRQ_HANDLED; /* Call the real timer interrupt handler */ + write_seqlock(&xtime_lock); do_timer(1); + write_sequnlock(&xtime_lock); return IRQ_HANDLED; } @@ -246,8 +231,7 @@ static struct irqaction irq_timer = { .name = "timer" }; -void __init -cris_timer_init(void) +void __init cris_timer_init(void) { int cpu = smp_processor_id(); reg_timer_rw_tmr0_ctrl tmr0_ctrl = { 0 }; @@ -273,8 +257,7 @@ cris_timer_init(void) REG_WR(timer, timer_regs[cpu], rw_intr_mask, timer_intr_mask); } -void __init -time_init(void) +void __init time_init(void) { reg_intr_vect_rw_mask intr_mask; diff --git a/arch/cris/kernel/time.c b/arch/cris/kernel/time.c index c72730d20ef6..b5096430ce1c 100644 --- a/arch/cris/kernel/time.c +++ b/arch/cris/kernel/time.c @@ -39,13 +39,16 @@ int have_rtc; /* used to remember if we have an RTC or not */; extern unsigned long loops_per_jiffy; /* init/main.c */ unsigned long loops_per_usec; + +#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET extern unsigned long do_slow_gettimeoffset(void); static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset; u32 arch_gettimeoffset(void) { - return do_gettimeoffset() * 1000; + return do_gettimeoffset() * 1000; } +#endif /* * BUG: This routine does not handle hour overflow properly; it just @@ -151,7 +154,7 @@ cris_do_profile(struct pt_regs* regs) unsigned long long sched_clock(void) { - return (unsigned long long)jiffies * (1000000000 / HZ) + + return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ) + get_ns_in_jiffie(); } -- cgit v1.2.2