/* * arch/arm/mach-pxa/time.c * * Author: Nicolas Pitre * Created: Jun 15, 2001 * Copyright: MontaVista Software Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/config.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/interrupt.h> #include <linux/time.h> #include <linux/signal.h> #include <linux/errno.h> #include <linux/sched.h> #include <asm/system.h> #include <asm/hardware.h> #include <asm/io.h> #include <asm/leds.h> #include <asm/irq.h> #include <asm/mach/irq.h> #include <asm/mach/time.h> #include <asm/arch/pxa-regs.h> static inline unsigned long pxa_get_rtc_time(void) { return RCNR; } static int pxa_set_rtc(void) { unsigned long current_time = xtime.tv_sec; if (RTSR & RTSR_ALE) { /* make sure not to forward the clock over an alarm */ unsigned long alarm = RTAR; if (current_time >= alarm && alarm >= RCNR) return -ERESTARTSYS; } RCNR = current_time; return 0; } /* IRQs are disabled before entering here from do_gettimeofday() */ static unsigned long pxa_gettimeoffset (void) { long ticks_to_match, elapsed, usec; /* Get ticks before next timer match */ ticks_to_match = OSMR0 - OSCR; /* We need elapsed ticks since last match */ elapsed = LATCH - ticks_to_match; /* don't get fooled by the workaround in pxa_timer_interrupt() */ if (elapsed <= 0) return 0; /* Now convert them to usec */ usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH; return usec; } static irqreturn_t pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) { int next_match; /* Loop until we get ahead of the free running timer. * This ensures an exact clock tick count and time accuracy. * IRQs are disabled inside the loop to ensure coherence between * lost_ticks (updated in do_timer()) and the match reg value, so we * can use do_gettimeofday() from interrupt handlers. * * HACK ALERT: it seems that the PXA timer regs aren't updated right * away in all cases when a write occurs. We therefore compare with * 8 instead of 0 in the while() condition below to avoid missing a * match if OSCR has already reached the next OSMR value. * Experience has shown that up to 6 ticks are needed to work around * this problem, but let's use 8 to be conservative. Note that this * affect things only when the timer IRQ has been delayed by nearly * exactly one tick period which should be a pretty rare event. */ do { timer_tick(regs); OSSR = OSSR_M0; /* Clear match on timer 0 */ next_match = (OSMR0 += LATCH); } while( (signed long)(next_match - OSCR) <= 8 ); return IRQ_HANDLED; } static struct irqaction pxa_timer_irq = { .name = "PXA Timer Tick", .flags = SA_INTERRUPT, .handler = pxa_timer_interrupt }; static void __init pxa_timer_init(void) { struct timespec tv; set_rtc = pxa_set_rtc; tv.tv_nsec = 0; tv.tv_sec = pxa_get_rtc_time(); do_settimeofday(&tv); OSMR0 = 0; /* set initial match at 0 */ OSSR = 0xf; /* clear status on all timers */ setup_irq(IRQ_OST0, &pxa_timer_irq); OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */ OSCR = 0; /* initialize free-running timer, force first match */ } #ifdef CONFIG_PM static unsigned long osmr[4], oier; static void pxa_timer_suspend(void) { osmr[0] = OSMR0; osmr[1] = OSMR1; osmr[2] = OSMR2; osmr[3] = OSMR3; oier = OIER; } static void pxa_timer_resume(void) { OSMR0 = osmr[0]; OSMR1 = osmr[1]; OSMR2 = osmr[2]; OSMR3 = osmr[3]; OIER = oier; /* * OSMR0 is the system timer: make sure OSCR is sufficiently behind */ OSCR = OSMR0 - LATCH; } #else #define pxa_timer_suspend NULL #define pxa_timer_resume NULL #endif struct sys_timer pxa_timer = { .init = pxa_timer_init, .suspend = pxa_timer_suspend, .resume = pxa_timer_resume, .offset = pxa_gettimeoffset, };