diff options
Diffstat (limited to 'arch/xtensa/kernel/time.c')
| -rw-r--r-- | arch/xtensa/kernel/time.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c new file mode 100644 index 000000000000..e07287db5a40 --- /dev/null +++ b/arch/xtensa/kernel/time.c @@ -0,0 +1,227 @@ +/* + * arch/xtensa/kernel/time.c + * + * Timer and clock support. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2005 Tensilica Inc. + * + * Chris Zankel <chris@zankel.net> + */ + +#include <linux/config.h> +#include <linux/errno.h> +#include <linux/time.h> +#include <linux/timex.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/irq.h> +#include <linux/profile.h> +#include <linux/delay.h> + +#include <asm/timex.h> +#include <asm/platform.h> + + +extern volatile unsigned long wall_jiffies; + +u64 jiffies_64 = INITIAL_JIFFIES; +EXPORT_SYMBOL(jiffies_64); + +spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED; +EXPORT_SYMBOL(rtc_lock); + + +#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT +unsigned long ccount_per_jiffy; /* per 1/HZ */ +unsigned long ccount_nsec; /* nsec per ccount increment */ +#endif + +unsigned int last_ccount_stamp; +static long last_rtc_update = 0; + +/* + * Scheduler clock - returns current tim in nanosec units. + */ + +unsigned long long sched_clock(void) +{ + return (unsigned long long)jiffies * (1000000000 / HZ); +} + +static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs); +static struct irqaction timer_irqaction = { + .handler = timer_interrupt, + .flags = SA_INTERRUPT, + .name = "timer", +}; + +void __init time_init(void) +{ + time_t sec_o, sec_n = 0; + + /* The platform must provide a function to calibrate the processor + * speed for the CALIBRATE. + */ + +#if CONFIG_XTENSA_CALIBRATE_CCOUNT + printk("Calibrating CPU frequency "); + platform_calibrate_ccount(); + printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ), + (int)(ccount_per_jiffy/(10000/HZ))%100); +#endif + + /* Set time from RTC (if provided) */ + + if (platform_get_rtc_time(&sec_o) == 0) + while (platform_get_rtc_time(&sec_n)) + if (sec_o != sec_n) + break; + + xtime.tv_nsec = 0; + last_rtc_update = xtime.tv_sec = sec_n; + last_ccount_stamp = get_ccount(); + + set_normalized_timespec(&wall_to_monotonic, + -xtime.tv_sec, -xtime.tv_nsec); + + /* Initialize the linux timer interrupt. */ + + setup_irq(LINUX_TIMER_INT, &timer_irqaction); + set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY); +} + + +int do_settimeofday(struct timespec *tv) +{ + time_t wtm_sec, sec = tv->tv_sec; + long wtm_nsec, nsec = tv->tv_nsec; + unsigned long ccount; + + if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) + return -EINVAL; + + write_seqlock_irq(&xtime_lock); + + /* This is revolting. We need to set "xtime" correctly. However, the + * value in this location is the value at the most recent update of + * wall time. Discover what correction gettimeofday() would have + * made, and then undo it! + */ + ccount = get_ccount(); + nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC; + nsec -= (jiffies - wall_jiffies) * CCOUNT_PER_JIFFY * CCOUNT_NSEC; + + wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); + wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); + + set_normalized_timespec(&xtime, sec, nsec); + set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); + + time_adjust = 0; /* stop active adjtime() */ + time_status |= STA_UNSYNC; + time_maxerror = NTP_PHASE_LIMIT; + time_esterror = NTP_PHASE_LIMIT; + write_sequnlock_irq(&xtime_lock); + return 0; +} + +EXPORT_SYMBOL(do_settimeofday); + + +void do_gettimeofday(struct timeval *tv) +{ + unsigned long flags; + unsigned long sec, usec, delta, lost, seq; + + do { + seq = read_seqbegin_irqsave(&xtime_lock, flags); + + delta = get_ccount() - last_ccount_stamp; + sec = xtime.tv_sec; + usec = (xtime.tv_nsec / NSEC_PER_USEC); + + lost = jiffies - wall_jiffies; + + } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); + + usec += lost * (1000000UL/HZ) + (delta * CCOUNT_NSEC) / NSEC_PER_USEC; + for (; usec >= 1000000; sec++, usec -= 1000000) + ; + + tv->tv_sec = sec; + tv->tv_usec = usec; +} + +EXPORT_SYMBOL(do_gettimeofday); + +/* + * The timer interrupt is called HZ times per second. + */ + +irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs) +{ + + unsigned long next; + + next = get_linux_timer(); + +again: + while ((signed long)(get_ccount() - next) > 0) { + + profile_tick(CPU_PROFILING, regs); +#ifndef CONFIG_SMP + update_process_times(user_mode(regs)); +#endif + + write_seqlock(&xtime_lock); + + last_ccount_stamp = next; + next += CCOUNT_PER_JIFFY; + do_timer (regs); /* Linux handler in kernel/timer.c */ + + if ((time_status & STA_UNSYNC) == 0 && + xtime.tv_sec - last_rtc_update >= 659 && + abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ && + jiffies - wall_jiffies == 1) { + + if (platform_set_rtc_time(xtime.tv_sec+1) == 0) + last_rtc_update = xtime.tv_sec+1; + else + /* Do it again in 60 s */ + last_rtc_update += 60; + } + write_sequnlock(&xtime_lock); + } + + /* NOTE: writing CCOMPAREn clears the interrupt. */ + + set_linux_timer (next); + + /* Make sure we didn't miss any tick... */ + + if ((signed long)(get_ccount() - next) > 0) + goto again; + + /* Allow platform to do something usefull (Wdog). */ + + platform_heartbeat(); + + return IRQ_HANDLED; +} + +#ifndef CONFIG_GENERIC_CALIBRATE_DELAY +void __devinit calibrate_delay(void) +{ + loops_per_jiffy = CCOUNT_PER_JIFFY; + printk("Calibrating delay loop (skipped)... " + "%lu.%02lu BogoMIPS preset\n", + loops_per_jiffy/(1000000/HZ), + (loops_per_jiffy/(10000/HZ)) % 100); +} +#endif + |