diff options
Diffstat (limited to 'arch/blackfin/kernel/time-ts.c')
| -rw-r--r-- | arch/blackfin/kernel/time-ts.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/arch/blackfin/kernel/time-ts.c b/arch/blackfin/kernel/time-ts.c new file mode 100644 index 000000000000..4482c47c09e5 --- /dev/null +++ b/arch/blackfin/kernel/time-ts.c @@ -0,0 +1,219 @@ +/* + * linux/arch/kernel/time-ts.c + * + * Based on arm clockevents implementation and old bfin time tick. + * + * Copyright(C) 2008, GeoTechnologies, Vitja Makarov + * + * This code is licenced under the GPL version 2. For details see + * kernel-base/COPYING. + */ +#include <linux/module.h> +#include <linux/profile.h> +#include <linux/interrupt.h> +#include <linux/time.h> +#include <linux/timex.h> +#include <linux/irq.h> +#include <linux/clocksource.h> +#include <linux/clockchips.h> +#include <linux/cpufreq.h> + +#include <asm/blackfin.h> +#include <asm/time.h> + +#ifdef CONFIG_CYCLES_CLOCKSOURCE + +/* Accelerators for sched_clock() + * convert from cycles(64bits) => nanoseconds (64bits) + * basic equation: + * ns = cycles / (freq / ns_per_sec) + * ns = cycles * (ns_per_sec / freq) + * ns = cycles * (10^9 / (cpu_khz * 10^3)) + * ns = cycles * (10^6 / cpu_khz) + * + * Then we use scaling math (suggested by george@mvista.com) to get: + * ns = cycles * (10^6 * SC / cpu_khz) / SC + * ns = cycles * cyc2ns_scale / SC + * + * And since SC is a constant power of two, we can convert the div + * into a shift. + * + * We can use khz divisor instead of mhz to keep a better precision, since + * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. + * (mathieu.desnoyers@polymtl.ca) + * + * -johnstul@us.ibm.com "math is hard, lets go shopping!" + */ + +static unsigned long cyc2ns_scale; +#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ + +static inline void set_cyc2ns_scale(unsigned long cpu_khz) +{ + cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz; +} + +static inline unsigned long long cycles_2_ns(cycle_t cyc) +{ + return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; +} + +static cycle_t read_cycles(void) +{ + return get_cycles(); +} + +unsigned long long sched_clock(void) +{ + return cycles_2_ns(read_cycles()); +} + +static struct clocksource clocksource_bfin = { + .name = "bfin_cycles", + .rating = 350, + .read = read_cycles, + .mask = CLOCKSOURCE_MASK(64), + .shift = 22, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int __init bfin_clocksource_init(void) +{ + set_cyc2ns_scale(get_cclk() / 1000); + + clocksource_bfin.mult = clocksource_hz2mult(get_cclk(), clocksource_bfin.shift); + + if (clocksource_register(&clocksource_bfin)) + panic("failed to register clocksource"); + + return 0; +} + +#else +# define bfin_clocksource_init() +#endif + +static int bfin_timer_set_next_event(unsigned long cycles, + struct clock_event_device *evt) +{ + bfin_write_TCOUNT(cycles); + CSYNC(); + return 0; +} + +static void bfin_timer_set_mode(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: { + unsigned long tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1); + bfin_write_TCNTL(TMPWR); + bfin_write_TSCALE(TIME_SCALE - 1); + CSYNC(); + bfin_write_TPERIOD(tcount); + bfin_write_TCOUNT(tcount); + bfin_write_TCNTL(TMPWR | TMREN | TAUTORLD); + CSYNC(); + break; + } + case CLOCK_EVT_MODE_ONESHOT: + bfin_write_TSCALE(0); + bfin_write_TCOUNT(0); + bfin_write_TCNTL(TMPWR | TMREN); + CSYNC(); + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + bfin_write_TCNTL(0); + CSYNC(); + break; + case CLOCK_EVT_MODE_RESUME: + break; + } +} + +static void __init bfin_timer_init(void) +{ + /* power up the timer, but don't enable it just yet */ + bfin_write_TCNTL(TMPWR); + CSYNC(); + + /* + * the TSCALE prescaler counter. + */ + bfin_write_TSCALE(TIME_SCALE - 1); + bfin_write_TPERIOD(0); + bfin_write_TCOUNT(0); + + /* now enable the timer */ + CSYNC(); +} + +/* + * timer_interrupt() needs to keep up the real-time clock, + * as well as call the "do_timer()" routine every clocktick + */ +#ifdef CONFIG_CORE_TIMER_IRQ_L1 +__attribute__((l1_text)) +#endif +irqreturn_t timer_interrupt(int irq, void *dev_id); + +static struct clock_event_device clockevent_bfin = { + .name = "bfin_core_timer", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .shift = 32, + .cpumask = CPU_MASK_CPU0, + .set_next_event = bfin_timer_set_next_event, + .set_mode = bfin_timer_set_mode, +}; + +static struct irqaction bfin_timer_irq = { + .name = "Blackfin Core Timer", + .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, + .handler = timer_interrupt, + .dev_id = &clockevent_bfin, +}; + +irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + evt->event_handler(evt); + return IRQ_HANDLED; +} + +static int __init bfin_clockevent_init(void) +{ + setup_irq(IRQ_CORETMR, &bfin_timer_irq); + bfin_timer_init(); + + clockevent_bfin.mult = div_sc(get_cclk(), NSEC_PER_SEC, clockevent_bfin.shift); + clockevent_bfin.max_delta_ns = clockevent_delta2ns(-1, &clockevent_bfin); + clockevent_bfin.min_delta_ns = clockevent_delta2ns(100, &clockevent_bfin); + clockevents_register_device(&clockevent_bfin); + + return 0; +} + +void __init time_init(void) +{ + time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */ + +#ifdef CONFIG_RTC_DRV_BFIN + /* [#2663] hack to filter junk RTC values that would cause + * userspace to have to deal with time values greater than + * 2^31 seconds (which uClibc cannot cope with yet) + */ + if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) { + printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n"); + bfin_write_RTC_STAT(0); + } +#endif + + /* Initialize xtime. From now on, xtime is updated with timer interrupts */ + xtime.tv_sec = secs_since_1970; + xtime.tv_nsec = 0; + set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); + + bfin_clocksource_init(); + bfin_clockevent_init(); +} |