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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mach-pxa/time.c | |
download | kernel_samsung_smdk4412-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip kernel_samsung_smdk4412-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz kernel_samsung_smdk4412-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.bz2 |
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'arch/arm/mach-pxa/time.c')
-rw-r--r-- | arch/arm/mach-pxa/time.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c new file mode 100644 index 0000000..473fb61 --- /dev/null +++ b/arch/arm/mach-pxa/time.c @@ -0,0 +1,164 @@ +/* + * 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; + + write_seqlock(&xtime_lock); + + /* 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 ); + + write_sequnlock(&xtime_lock); + + 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, +}; |