diff options
Diffstat (limited to 'drivers/clocksource/pxa_timer.c')
| -rw-r--r-- | drivers/clocksource/pxa_timer.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/drivers/clocksource/pxa_timer.c b/drivers/clocksource/pxa_timer.c new file mode 100644 index 000000000000..fca174e3865d --- /dev/null +++ b/drivers/clocksource/pxa_timer.c @@ -0,0 +1,162 @@ +/* + * 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 <linux/sched_clock.h> + +#include <asm/div64.h> +#include <asm/mach/irq.h> +#include <asm/mach/time.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 u64 notrace pxa_read_sched_clock(void) +{ + return readl_relaxed(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. */ + writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER); + writel_relaxed(OSSR_M0, OSSR); + 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; + + writel_relaxed(readl_relaxed(OIER) | OIER_E0, OIER); + next = readl_relaxed(OSCR) + delta; + writel_relaxed(next, OSMR0); + oscr = readl_relaxed(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: + writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER); + writel_relaxed(OSSR_M0, OSSR); + break; + + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + /* initializing, released, or preparing for suspend */ + writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER); + writel_relaxed(OSSR_M0, OSSR); + break; + + case CLOCK_EVT_MODE_RESUME: + case CLOCK_EVT_MODE_PERIODIC: + break; + } +} + +#ifdef CONFIG_PM +static unsigned long osmr[4], oier, oscr; + +static void pxa_timer_suspend(struct clock_event_device *cedev) +{ + osmr[0] = readl_relaxed(OSMR0); + osmr[1] = readl_relaxed(OSMR1); + osmr[2] = readl_relaxed(OSMR2); + osmr[3] = readl_relaxed(OSMR3); + oier = readl_relaxed(OIER); + oscr = readl_relaxed(OSCR); +} + +static void pxa_timer_resume(struct clock_event_device *cedev) +{ + /* + * 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; + + writel_relaxed(osmr[0], OSMR0); + writel_relaxed(osmr[1], OSMR1); + writel_relaxed(osmr[2], OSMR2); + writel_relaxed(osmr[3], OSMR3); + writel_relaxed(oier, OIER); + writel_relaxed(oscr, OSCR); +} +#else +#define pxa_timer_suspend NULL +#define pxa_timer_resume NULL +#endif + +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, + .suspend = pxa_timer_suspend, + .resume = pxa_timer_resume, +}; + +static struct irqaction pxa_ost0_irq = { + .name = "ost0", + .flags = IRQF_TIMER | IRQF_IRQPOLL, + .handler = pxa_ost0_interrupt, + .dev_id = &ckevt_pxa_osmr0, +}; + +void __init pxa_timer_init(void) +{ + unsigned long clock_tick_rate = get_clock_tick_rate(); + + writel_relaxed(0, OIER); + writel_relaxed(OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3, OSSR); + + sched_clock_register(pxa_read_sched_clock, 32, clock_tick_rate); + + 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_config_and_register(&ckevt_pxa_osmr0, clock_tick_rate, + MIN_OSCR_DELTA * 2, 0x7fffffff); +} |