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Diffstat (limited to 'arch/arm/mach-pxa/time.c')
| -rw-r--r-- | arch/arm/mach-pxa/time.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c new file mode 100644 index 00000000..3d6c9bd9 --- /dev/null +++ b/arch/arm/mach-pxa/time.c @@ -0,0 +1,170 @@ +/* + * arch/arm/mach-pxa/time.c + * + * 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 + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/clockchips.h> + +#include <asm/div64.h> +#include <asm/mach/irq.h> +#include <asm/mach/time.h> +#include <asm/sched_clock.h> +#include <mach/regs-ost.h> +#include <mach/irqs.h> + +/* + * This is PXA's sched_clock implementation. This has a resolution + * of at least 308 ns and a maximum value of 208 days. + * + * The return value is guaranteed to be monotonic in that range as + * long as there is always less than 582 seconds between successive + * calls to sched_clock() which should always be the case in practice. + */ + +static u32 notrace pxa_read_sched_clock(void) +{ + return OSCR; +} + + +#define MIN_OSCR_DELTA 16 + +static irqreturn_t +pxa_ost0_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *c = dev_id; + + /* Disarm the compare/match, signal the event. */ + OIER &= ~OIER_E0; + OSSR = OSSR_M0; + c->event_handler(c); + + return IRQ_HANDLED; +} + +static int +pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev) +{ + unsigned long next, oscr; + + OIER |= OIER_E0; + next = OSCR + delta; + OSMR0 = next; + oscr = OSCR; + + return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0; +} + +static void +pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev) +{ + switch (mode) { + case CLOCK_EVT_MODE_ONESHOT: + OIER &= ~OIER_E0; + OSSR = OSSR_M0; + break; + + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + /* initializing, released, or preparing for suspend */ + OIER &= ~OIER_E0; + OSSR = OSSR_M0; + break; + + case CLOCK_EVT_MODE_RESUME: + case CLOCK_EVT_MODE_PERIODIC: + break; + } +} + +static struct clock_event_device ckevt_pxa_osmr0 = { + .name = "osmr0", + .features = CLOCK_EVT_FEAT_ONESHOT, + .rating = 200, + .set_next_event = pxa_osmr0_set_next_event, + .set_mode = pxa_osmr0_set_mode, +}; + +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) +{ + unsigned long clock_tick_rate = get_clock_tick_rate(); + + OIER = 0; + OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3; + + setup_sched_clock(pxa_read_sched_clock, 32, clock_tick_rate); + + clockevents_calc_mult_shift(&ckevt_pxa_osmr0, clock_tick_rate, 4); + ckevt_pxa_osmr0.max_delta_ns = + clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0); + ckevt_pxa_osmr0.min_delta_ns = + clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_pxa_osmr0) + 1; + ckevt_pxa_osmr0.cpumask = cpumask_of(0); + + setup_irq(IRQ_OST0, &pxa_ost0_irq); + + clocksource_mmio_init(&OSCR, "oscr0", clock_tick_rate, 200, 32, + clocksource_mmio_readl_up); + clockevents_register_device(&ckevt_pxa_osmr0); +} + +#ifdef CONFIG_PM +static unsigned long osmr[4], oier, oscr; + +static void pxa_timer_suspend(void) +{ + osmr[0] = OSMR0; + osmr[1] = OSMR1; + osmr[2] = OSMR2; + osmr[3] = OSMR3; + oier = OIER; + oscr = OSCR; +} + +static void pxa_timer_resume(void) +{ + /* + * Ensure that we have at least MIN_OSCR_DELTA between match + * register 0 and the OSCR, to guarantee that we will receive + * the one-shot timer interrupt. We adjust OSMR0 in preference + * to OSCR to guarantee that OSCR is monotonically incrementing. + */ + if (osmr[0] - oscr < MIN_OSCR_DELTA) + osmr[0] += MIN_OSCR_DELTA; + + OSMR0 = osmr[0]; + OSMR1 = osmr[1]; + OSMR2 = osmr[2]; + OSMR3 = osmr[3]; + OIER = oier; + OSCR = oscr; +} +#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, +}; |