diff options
| -rw-r--r-- | arch/arm/mach-pxa/time.c | 258 |
1 files changed, 128 insertions, 130 deletions
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c index 6f91fd2d061..98d27e646b0 100644 --- a/arch/arm/mach-pxa/time.c +++ b/arch/arm/mach-pxa/time.c @@ -1,9 +1,11 @@ /* * arch/arm/mach-pxa/time.c * - * Author: Nicolas Pitre - * Created: Jun 15, 2001 - * Copyright: MontaVista Software Inc. + * PXA clocksource, clockevents, and OST interrupt handlers. + * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>. + * + * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001 + * by MontaVista Software, Inc. (Nico, your code rocks!) * * 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 @@ -12,164 +14,160 @@ #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 <linux/clocksource.h> - -#include <asm/system.h> -#include <asm/hardware.h> -#include <asm/io.h> -#include <asm/leds.h> -#include <asm/irq.h> +#include <linux/clockchips.h> + #include <asm/mach/irq.h> #include <asm/mach/time.h> #include <asm/arch/pxa-regs.h> - -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; -} - -#ifdef CONFIG_NO_IDLE_HZ -static unsigned long initial_match; -static int match_posponed; -#endif - static irqreturn_t -pxa_timer_interrupt(int irq, void *dev_id) +pxa_ost0_interrupt(int irq, void *dev_id) { int next_match; - - write_seqlock(&xtime_lock); - -#ifdef CONFIG_NO_IDLE_HZ - if (match_posponed) { - match_posponed = 0; - OSMR0 = initial_match; - } -#endif - - /* Loop until we get ahead of the free running timer. - * This ensures an exact clock tick count and time accuracy. - * Since IRQs are disabled at this point, coherence between - * lost_ticks(updated in do_timer()) and the match reg value is - * ensured, hence 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. + struct clock_event_device *c = dev_id; + + if (c->mode == CLOCK_EVT_MODE_ONESHOT) { + /* Disarm the compare/match, signal the event. */ + OIER &= ~OIER_E0; + c->event_handler(c); + } else if (c->mode == CLOCK_EVT_MODE_PERIODIC) { + /* Call the event handler as many times as necessary + * to recover missed events, if any (if we update + * OSMR0 and OSCR0 is still ahead of us, we've missed + * the event). As we're dealing with that, re-arm the + * compare/match for the next event. + * + * HACK ALERT: + * + * There's a latency between the instruction that + * writes to OSMR0 and the actual commit to the + * physical hardware, because the CPU doesn't (have + * to) run at bus speed, there's a write buffer + * between the CPU and the bus, etc. etc. So if the + * target OSCR0 is "very close", to the OSMR0 load + * value, the update to OSMR0 might not get to the + * hardware in time and we'll miss that interrupt. + * + * To be safe, if the new OSMR0 is "very close" to the + * target OSCR0 value, we call the event_handler as + * though the event actually happened. According to + * Nico's comment in the previous version of this + * code, experience has shown that 6 OSCR ticks is + * "very close" but he went with 8. We will use 16, + * based on the results of testing on PXA270. + * + * To be doubly sure, we also tell clkevt via + * clockevents_register_device() not to ask for + * anything that might put us "very close". */ +#define MIN_OSCR_DELTA 16 do { - timer_tick(); - OSSR = OSSR_M0; /* Clear match on timer 0 */ + OSSR = OSSR_M0; next_match = (OSMR0 += LATCH); - } while( (signed long)(next_match - OSCR) <= 8 ); - - write_sequnlock(&xtime_lock); + c->event_handler(c); + } while (((signed long)(next_match - OSCR) <= MIN_OSCR_DELTA) + && (c->mode == CLOCK_EVT_MODE_PERIODIC)); + } return IRQ_HANDLED; } -static struct irqaction pxa_timer_irq = { - .name = "PXA Timer Tick", - .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, - .handler = pxa_timer_interrupt, +static int +pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev) +{ + unsigned long irqflags; + + raw_local_irq_save(irqflags); + OSMR0 = OSCR + delta; + OSSR = OSSR_M0; + OIER |= OIER_E0; + raw_local_irq_restore(irqflags); + return 0; +} + +static void +pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev) +{ + unsigned long irqflags; + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + raw_local_irq_save(irqflags); + OSMR0 = OSCR + LATCH; + OSSR = OSSR_M0; + OIER |= OIER_E0; + raw_local_irq_restore(irqflags); + break; + + case CLOCK_EVT_MODE_ONESHOT: + raw_local_irq_save(irqflags); + OIER &= ~OIER_E0; + raw_local_irq_restore(irqflags); + break; + + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + /* initializing, released, or preparing for suspend */ + raw_local_irq_save(irqflags); + OIER &= ~OIER_E0; + raw_local_irq_restore(irqflags); + break; + } +} + +static struct clock_event_device ckevt_pxa_osmr0 = { + .name = "osmr0", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .shift = 32, + .rating = 200, + .cpumask = CPU_MASK_CPU0, + .set_next_event = pxa_osmr0_set_next_event, + .set_mode = pxa_osmr0_set_mode, }; -static cycle_t pxa_get_cycles(void) +static cycle_t pxa_read_oscr(void) { return OSCR; } -static struct clocksource clocksource_pxa = { - .name = "pxa_timer", +static struct clocksource cksrc_pxa_oscr0 = { + .name = "oscr0", .rating = 200, - .read = pxa_get_cycles, + .read = pxa_read_oscr, .mask = CLOCKSOURCE_MASK(32), .shift = 20, .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +static struct irqaction pxa_ost0_irq = { + .name = "ost0", + .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, + .handler = pxa_ost0_interrupt, + .dev_id = &ckevt_pxa_osmr0, +}; + static void __init pxa_timer_init(void) { - struct timespec tv; - unsigned long flags; + OIER = 0; + OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3; - set_rtc = pxa_set_rtc; + ckevt_pxa_osmr0.mult = + div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, ckevt_pxa_osmr0.shift); + ckevt_pxa_osmr0.max_delta_ns = + clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0); + ckevt_pxa_osmr0.min_delta_ns = + clockevent_delta2ns(MIN_OSCR_DELTA, &ckevt_pxa_osmr0) + 1; - OIER = 0; /* disable any timer interrupts */ - OSSR = 0xf; /* clear status on all timers */ - setup_irq(IRQ_OST0, &pxa_timer_irq); - local_irq_save(flags); - OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */ - OSMR0 = OSCR + LATCH; /* set initial match */ - local_irq_restore(flags); - - /* - * OSCR runs continuously on PXA and is not written to, - * so we can use it as clock source directly. - */ - clocksource_pxa.mult = - clocksource_hz2mult(CLOCK_TICK_RATE, clocksource_pxa.shift); - clocksource_register(&clocksource_pxa); -} - -#ifdef CONFIG_NO_IDLE_HZ -static int pxa_dyn_tick_enable_disable(void) -{ - /* nothing to do */ - return 0; -} + cksrc_pxa_oscr0.mult = + clocksource_hz2mult(CLOCK_TICK_RATE, cksrc_pxa_oscr0.shift); -static void pxa_dyn_tick_reprogram(unsigned long ticks) -{ - if (ticks > 1) { - initial_match = OSMR0; - OSMR0 = initial_match + ticks * LATCH; - match_posponed = 1; - } -} + setup_irq(IRQ_OST0, &pxa_ost0_irq); -static irqreturn_t -pxa_dyn_tick_handler(int irq, void *dev_id) -{ - if (match_posponed) { - match_posponed = 0; - OSMR0 = initial_match; - if ( (signed long)(initial_match - OSCR) <= 8 ) - return pxa_timer_interrupt(irq, dev_id); - } - return IRQ_NONE; + clocksource_register(&cksrc_pxa_oscr0); + clockevents_register_device(&ckevt_pxa_osmr0); } -static struct dyn_tick_timer pxa_dyn_tick = { - .enable = pxa_dyn_tick_enable_disable, - .disable = pxa_dyn_tick_enable_disable, - .reprogram = pxa_dyn_tick_reprogram, - .handler = pxa_dyn_tick_handler, -}; -#endif - #ifdef CONFIG_PM static unsigned long osmr[4], oier; @@ -191,7 +189,10 @@ static void pxa_timer_resume(void) OIER = oier; /* - * OSMR0 is the system timer: make sure OSCR is sufficiently behind + * OSCR0 is the system timer, which has to increase + * monotonically until it rolls over in hardware. The value + * (OSMR0 - LATCH) is OSCR0 at the most recent system tick, + * which is a handy value to restore to OSCR0. */ OSCR = OSMR0 - LATCH; } @@ -204,7 +205,4 @@ struct sys_timer pxa_timer = { .init = pxa_timer_init, .suspend = pxa_timer_suspend, .resume = pxa_timer_resume, -#ifdef CONFIG_NO_IDLE_HZ - .dyn_tick = &pxa_dyn_tick, -#endif }; |