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Diffstat (limited to 'arch/xtensa/kernel/time.c')
| -rw-r--r-- | arch/xtensa/kernel/time.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c new file mode 100644 index 000000000..2a1823de6 --- /dev/null +++ b/arch/xtensa/kernel/time.c @@ -0,0 +1,181 @@ +/* + * arch/xtensa/kernel/time.c + * + * Timer and clock support. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2005 Tensilica Inc. + * + * Chris Zankel <chris@zankel.net> + */ + +#include <linux/errno.h> +#include <linux/sched.h> +#include <linux/time.h> +#include <linux/clocksource.h> +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/irq.h> +#include <linux/profile.h> +#include <linux/delay.h> +#include <linux/irqdomain.h> +#include <linux/sched_clock.h> + +#include <asm/timex.h> +#include <asm/platform.h> + +unsigned long ccount_freq; /* ccount Hz */ +EXPORT_SYMBOL(ccount_freq); + +static cycle_t ccount_read(struct clocksource *cs) +{ + return (cycle_t)get_ccount(); +} + +static u64 notrace ccount_sched_clock_read(void) +{ + return get_ccount(); +} + +static struct clocksource ccount_clocksource = { + .name = "ccount", + .rating = 200, + .read = ccount_read, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int ccount_timer_set_next_event(unsigned long delta, + struct clock_event_device *dev); +static void ccount_timer_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt); +struct ccount_timer { + struct clock_event_device evt; + int irq_enabled; + char name[24]; +}; +static DEFINE_PER_CPU(struct ccount_timer, ccount_timer); + +static int ccount_timer_set_next_event(unsigned long delta, + struct clock_event_device *dev) +{ + unsigned long flags, next; + int ret = 0; + + local_irq_save(flags); + next = get_ccount() + delta; + set_linux_timer(next); + if (next - get_ccount() > delta) + ret = -ETIME; + local_irq_restore(flags); + + return ret; +} + +static void ccount_timer_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + struct ccount_timer *timer = + container_of(evt, struct ccount_timer, evt); + + /* + * There is no way to disable the timer interrupt at the device level, + * only at the intenable register itself. Since enable_irq/disable_irq + * calls are nested, we need to make sure that these calls are + * balanced. + */ + switch (mode) { + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + if (timer->irq_enabled) { + disable_irq(evt->irq); + timer->irq_enabled = 0; + } + break; + case CLOCK_EVT_MODE_RESUME: + case CLOCK_EVT_MODE_ONESHOT: + if (!timer->irq_enabled) { + enable_irq(evt->irq); + timer->irq_enabled = 1; + } + default: + break; + } +} + +static irqreturn_t timer_interrupt(int irq, void *dev_id); +static struct irqaction timer_irqaction = { + .handler = timer_interrupt, + .flags = IRQF_TIMER, + .name = "timer", +}; + +void local_timer_setup(unsigned cpu) +{ + struct ccount_timer *timer = &per_cpu(ccount_timer, cpu); + struct clock_event_device *clockevent = &timer->evt; + + timer->irq_enabled = 1; + clockevent->name = timer->name; + snprintf(timer->name, sizeof(timer->name), "ccount_clockevent_%u", cpu); + clockevent->features = CLOCK_EVT_FEAT_ONESHOT; + clockevent->rating = 300; + clockevent->set_next_event = ccount_timer_set_next_event; + clockevent->set_mode = ccount_timer_set_mode; + clockevent->cpumask = cpumask_of(cpu); + clockevent->irq = irq_create_mapping(NULL, LINUX_TIMER_INT); + if (WARN(!clockevent->irq, "error: can't map timer irq")) + return; + clockevents_config_and_register(clockevent, ccount_freq, + 0xf, 0xffffffff); +} + +void __init time_init(void) +{ +#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT + printk("Calibrating CPU frequency "); + platform_calibrate_ccount(); + printk("%d.%02d MHz\n", (int)ccount_freq/1000000, + (int)(ccount_freq/10000)%100); +#else + ccount_freq = CONFIG_XTENSA_CPU_CLOCK*1000000UL; +#endif + clocksource_register_hz(&ccount_clocksource, ccount_freq); + local_timer_setup(0); + setup_irq(this_cpu_ptr(&ccount_timer)->evt.irq, &timer_irqaction); + sched_clock_register(ccount_sched_clock_read, 32, ccount_freq); + clocksource_of_init(); +} + +/* + * The timer interrupt is called HZ times per second. + */ + +irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = &this_cpu_ptr(&ccount_timer)->evt; + + set_linux_timer(get_linux_timer()); + evt->event_handler(evt); + + /* Allow platform to do something useful (Wdog). */ + platform_heartbeat(); + + return IRQ_HANDLED; +} + +#ifndef CONFIG_GENERIC_CALIBRATE_DELAY +void calibrate_delay(void) +{ + loops_per_jiffy = ccount_freq / HZ; + printk("Calibrating delay loop (skipped)... " + "%lu.%02lu BogoMIPS preset\n", + loops_per_jiffy/(1000000/HZ), + (loops_per_jiffy/(10000/HZ)) % 100); +} +#endif |