/*
* 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,
.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);
clockevent_bfin.cpumask = cpumask_of(0);
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();
}
