/* * 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 <asm/sysreg.h> #include <mach/pm.h> static cycle_t read_cycle_count(void) { 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), .shift = 16, .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_DISABLED | 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: cpu_disable_idle_sleep(); break; case CLOCK_EVT_MODE_UNUSED: case CLOCK_EVT_MODE_SHUTDOWN: sysreg_write(COMPARE, 0); pr_debug("%s: stop\n", evdev->name); cpu_enable_idle_sleep(); break; default: BUG(); } } static struct clock_event_device comparator = { .name = "avr32_comparator", .features = CLOCK_EVT_FEAT_ONESHOT, .shift = 16, .rating = 50, .cpumask = CPU_MASK_CPU0, .set_next_event = comparator_next_event, .set_mode = comparator_mode, }; void __init time_init(void) { unsigned long counter_hz; int ret; xtime.tv_sec = mktime(2007, 1, 1, 0, 0, 0); xtime.tv_nsec = 0; set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); /* figure rate for counter */ counter_hz = clk_get_rate(boot_cpu_data.clk); counter.mult = clocksource_hz2mult(counter_hz, counter.shift); ret = clocksource_register(&counter); 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; 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); } }