diff options
Diffstat (limited to 'arch/avr32/kernel/time.c')
| -rw-r--r-- | arch/avr32/kernel/time.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/arch/avr32/kernel/time.c b/arch/avr32/kernel/time.c new file mode 100644 index 000000000000..b0e6b5855a38 --- /dev/null +++ b/arch/avr32/kernel/time.c @@ -0,0 +1,238 @@ +/* + * Copyright (C) 2004-2006 Atmel Corporation + * + * Based on MIPS implementation arch/mips/kernel/time.c + * Copyright 2001 MontaVista Software Inc. + * + * 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/clocksource.h> +#include <linux/time.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/kernel_stat.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/profile.h> +#include <linux/sysdev.h> + +#include <asm/div64.h> +#include <asm/sysreg.h> +#include <asm/io.h> +#include <asm/sections.h> + +static cycle_t read_cycle_count(void) +{ + return (cycle_t)sysreg_read(COUNT); +} + +static struct clocksource clocksource_avr32 = { + .name = "avr32", + .rating = 350, + .read = read_cycle_count, + .mask = CLOCKSOURCE_MASK(32), + .shift = 16, + .is_continuous = 1, +}; + +/* + * By default we provide the null RTC ops + */ +static unsigned long null_rtc_get_time(void) +{ + return mktime(2004, 1, 1, 0, 0, 0); +} + +static int null_rtc_set_time(unsigned long sec) +{ + return 0; +} + +static unsigned long (*rtc_get_time)(void) = null_rtc_get_time; +static int (*rtc_set_time)(unsigned long) = null_rtc_set_time; + +/* how many counter cycles in a jiffy? */ +static unsigned long cycles_per_jiffy; + +/* cycle counter value at the previous timer interrupt */ +static unsigned int timerhi, timerlo; + +/* the count value for the next timer interrupt */ +static unsigned int expirelo; + +static void avr32_timer_ack(void) +{ + unsigned int count; + + /* Ack this timer interrupt and set the next one */ + expirelo += cycles_per_jiffy; + if (expirelo == 0) { + printk(KERN_DEBUG "expirelo == 0\n"); + sysreg_write(COMPARE, expirelo + 1); + } else { + sysreg_write(COMPARE, expirelo); + } + + /* Check to see if we have missed any timer interrupts */ + count = sysreg_read(COUNT); + if ((count - expirelo) < 0x7fffffff) { + expirelo = count + cycles_per_jiffy; + sysreg_write(COMPARE, expirelo); + } +} + +static unsigned int avr32_hpt_read(void) +{ + return sysreg_read(COUNT); +} + +/* + * Taken from MIPS c0_hpt_timer_init(). + * + * Why is it so complicated, and what is "count"? My assumption is + * that `count' specifies the "reference cycle", i.e. the cycle since + * reset that should mean "zero". The reason COUNT is written twice is + * probably to make sure we don't get any timer interrupts while we + * are messing with the counter. + */ +static void avr32_hpt_init(unsigned int count) +{ + count = sysreg_read(COUNT) - count; + expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy; + sysreg_write(COUNT, expirelo - cycles_per_jiffy); + sysreg_write(COMPARE, expirelo); + sysreg_write(COUNT, count); +} + +/* + * Scheduler clock - returns current time in nanosec units. + */ +unsigned long long sched_clock(void) +{ + /* There must be better ways...? */ + return (unsigned long long)jiffies * (1000000000 / HZ); +} + +/* + * local_timer_interrupt() does profiling and process accounting on a + * per-CPU basis. + * + * In UP mode, it is invoked from the (global) timer_interrupt. + */ +static void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + if (current->pid) + profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(regs)); +} + +static irqreturn_t +timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + unsigned int count; + + /* ack timer interrupt and try to set next interrupt */ + count = avr32_hpt_read(); + avr32_timer_ack(); + + /* Update timerhi/timerlo for intra-jiffy calibration */ + timerhi += count < timerlo; /* Wrap around */ + timerlo = count; + + /* + * Call the generic timer interrupt handler + */ + write_seqlock(&xtime_lock); + do_timer(regs); + write_sequnlock(&xtime_lock); + + /* + * In UP mode, we call local_timer_interrupt() to do profiling + * and process accounting. + * + * SMP is not supported yet. + */ + local_timer_interrupt(irq, dev_id, regs); + + return IRQ_HANDLED; +} + +static struct irqaction timer_irqaction = { + .handler = timer_interrupt, + .flags = IRQF_DISABLED, + .name = "timer", +}; + +void __init time_init(void) +{ + unsigned long mult, shift, count_hz; + int ret; + + xtime.tv_sec = rtc_get_time(); + xtime.tv_nsec = 0; + + set_normalized_timespec(&wall_to_monotonic, + -xtime.tv_sec, -xtime.tv_nsec); + + printk("Before time_init: count=%08lx, compare=%08lx\n", + (unsigned long)sysreg_read(COUNT), + (unsigned long)sysreg_read(COMPARE)); + + count_hz = clk_get_rate(boot_cpu_data.clk); + shift = clocksource_avr32.shift; + mult = clocksource_hz2mult(count_hz, shift); + clocksource_avr32.mult = mult; + + printk("Cycle counter: mult=%lu, shift=%lu\n", mult, shift); + + { + u64 tmp; + + tmp = TICK_NSEC; + tmp <<= shift; + tmp += mult / 2; + do_div(tmp, mult); + + cycles_per_jiffy = tmp; + } + + /* This sets up the high precision timer for the first interrupt. */ + avr32_hpt_init(avr32_hpt_read()); + + printk("After time_init: count=%08lx, compare=%08lx\n", + (unsigned long)sysreg_read(COUNT), + (unsigned long)sysreg_read(COMPARE)); + + ret = clocksource_register(&clocksource_avr32); + if (ret) + printk(KERN_ERR + "timer: could not register clocksource: %d\n", ret); + + ret = setup_irq(0, &timer_irqaction); + if (ret) + printk("timer: could not request IRQ 0: %d\n", ret); +} + +static struct sysdev_class timer_class = { + set_kset_name("timer"), +}; + +static struct sys_device timer_device = { + .id = 0, + .cls = &timer_class, +}; + +static int __init init_timer_sysfs(void) +{ + int err = sysdev_class_register(&timer_class); + if (!err) + err = sysdev_register(&timer_device); + return err; +} + +device_initcall(init_timer_sysfs); |