/* * 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 __bfin_cycles_off + (get_cycles() << __bfin_cycles_mod); } 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(TIME_SCALE - 1); 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) { unsigned long timer_clk; timer_clk = get_cclk() / TIME_SCALE; setup_irq(IRQ_CORETMR, &bfin_timer_irq); bfin_timer_init(); clockevent_bfin.mult = div_sc(timer_clk, 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(); }