diff options
Diffstat (limited to 'arch/avr32/kernel/time.c')
| -rw-r--r-- | arch/avr32/kernel/time.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/arch/avr32/kernel/time.c b/arch/avr32/kernel/time.c new file mode 100644 index 000000000..d0f771be9 --- /dev/null +++ b/arch/avr32/kernel/time.c @@ -0,0 +1,160 @@ +/* + * Copyright (C) 2004-2007 Atmel Corporation + * + * 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/clk.h> +#include <linux/clockchips.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/kernel.h> +#include <linux/time.h> +#include <linux/cpu.h> + +#include <asm/sysreg.h> + +#include <mach/pm.h> + + +static cycle_t read_cycle_count(struct clocksource *cs) +{ + return (cycle_t)sysreg_read(COUNT); +} + +/* + * The architectural cycle count registers are a fine clocksource unless + * the system idle loop use sleep states like "idle": the CPU cycles + * measured by COUNT (and COMPARE) don't happen during sleep states. + * Their duration also changes if cpufreq changes the CPU clock rate. + * So we rate the clocksource using COUNT as very low quality. + */ +static struct clocksource counter = { + .name = "avr32_counter", + .rating = 50, + .read = read_cycle_count, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evdev = dev_id; + + if (unlikely(!(intc_get_pending(0) & 1))) + return IRQ_NONE; + + /* + * Disable the interrupt until the clockevent subsystem + * reprograms it. + */ + sysreg_write(COMPARE, 0); + + evdev->event_handler(evdev); + return IRQ_HANDLED; +} + +static struct irqaction timer_irqaction = { + .handler = timer_interrupt, + /* Oprofile uses the same irq as the timer, so allow it to be shared */ + .flags = IRQF_TIMER | IRQF_SHARED, + .name = "avr32_comparator", +}; + +static int comparator_next_event(unsigned long delta, + struct clock_event_device *evdev) +{ + unsigned long flags; + + raw_local_irq_save(flags); + + /* The time to read COUNT then update COMPARE must be less + * than the min_delta_ns value for this clockevent source. + */ + sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1); + + raw_local_irq_restore(flags); + + return 0; +} + +static void comparator_mode(enum clock_event_mode mode, + struct clock_event_device *evdev) +{ + switch (mode) { + case CLOCK_EVT_MODE_ONESHOT: + pr_debug("%s: start\n", evdev->name); + /* FALLTHROUGH */ + case CLOCK_EVT_MODE_RESUME: + /* + * If we're using the COUNT and COMPARE registers we + * need to force idle poll. + */ + cpu_idle_poll_ctrl(true); + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + sysreg_write(COMPARE, 0); + pr_debug("%s: stop\n", evdev->name); + if (evdev->mode == CLOCK_EVT_MODE_ONESHOT || + evdev->mode == CLOCK_EVT_MODE_RESUME) { + /* + * Only disable idle poll if we have forced that + * in a previous call. + */ + cpu_idle_poll_ctrl(false); + } + break; + default: + BUG(); + } +} + +static struct clock_event_device comparator = { + .name = "avr32_comparator", + .features = CLOCK_EVT_FEAT_ONESHOT, + .shift = 16, + .rating = 50, + .set_next_event = comparator_next_event, + .set_mode = comparator_mode, +}; + +void read_persistent_clock(struct timespec *ts) +{ + ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0); + ts->tv_nsec = 0; +} + +void __init time_init(void) +{ + unsigned long counter_hz; + int ret; + + /* figure rate for counter */ + counter_hz = clk_get_rate(boot_cpu_data.clk); + ret = clocksource_register_hz(&counter, counter_hz); + if (ret) + pr_debug("timer: could not register clocksource: %d\n", ret); + + /* setup COMPARE clockevent */ + comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift); + comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator); + comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1; + comparator.cpumask = cpumask_of(0); + + sysreg_write(COMPARE, 0); + timer_irqaction.dev_id = &comparator; + + ret = setup_irq(0, &timer_irqaction); + if (ret) + pr_debug("timer: could not request IRQ 0: %d\n", ret); + else { + clockevents_register_device(&comparator); + + pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name, + ((counter_hz + 500) / 1000) / 1000, + ((counter_hz + 500) / 1000) % 1000); + } +} |