| /* |
| * 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 u32 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); |
| |
| setup_sched_clock(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); |
| } |