static inline unsigned long read_CRTR(void)
{
unsigned long x1, x2;
x1 = at91_st_read(AT91_ST_CRTR);
do {
x2 = at91_st_read(AT91_ST_CRTR);
if (x1 == x2)
break;
x1 = x2;
} while (1);
return x1;
}
static void
clkevt32k_mode(enum clock_event_mode mode, struct clock_event_device *dev)
{
at91_st_write(AT91_ST_IDR, AT91_ST_PITS | AT91_ST_ALMS);
at91_st_read(AT91_ST_SR);
last_crtr = read_CRTR();
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
irqmask = AT91_ST_PITS;
at91_st_write(AT91_ST_PIMR, RM9200_TIMER_LATCH);
break;
case CLOCK_EVT_MODE_ONESHOT:
irqmask = AT91_ST_ALMS;
at91_st_write(AT91_ST_RTAR, last_crtr);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
irqmask = 0;
break;
}
at91_st_write(AT91_ST_IER, irqmask);
}
static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id)
{
u32 sr = at91_st_read(AT91_ST_SR) & irqmask;
WARN_ON_ONCE(!irqs_disabled());
if (sr & AT91_ST_ALMS) {
clkevt.event_handler(&clkevt);
return IRQ_HANDLED;
}
if (sr & AT91_ST_PITS) {
u32 crtr = read_CRTR();
while (((crtr - last_crtr) & AT91_ST_CRTV) >= RM9200_TIMER_LATCH) {
last_crtr += RM9200_TIMER_LATCH;
clkevt.event_handler(&clkevt);
}
return IRQ_HANDLED;
}
return IRQ_NONE;
}
/*
* IRQ handler for the timer.
*/
static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id)
{
u32 sr = at91_st_read(AT91_ST_SR) & irqmask;
/*
* irqs should be disabled here, but as the irq is shared they are only
* guaranteed to be off if the timer irq is registered first.
*/
WARN_ON_ONCE(!irqs_disabled());
/* simulate "oneshot" timer with alarm */
if (sr & AT91_ST_ALMS) {
clkevt.event_handler(&clkevt);
return IRQ_HANDLED;
}
/* periodic mode should handle delayed ticks */
if (sr & AT91_ST_PITS) {
u32 crtr = read_CRTR();
while (((crtr - last_crtr) & AT91_ST_CRTV) >= RM9200_TIMER_LATCH) {
last_crtr += RM9200_TIMER_LATCH;
clkevt.event_handler(&clkevt);
}
return IRQ_HANDLED;
}
/* this irq is shared ... */
return IRQ_NONE;
}
/*
* ST (system timer) module supports both clockevents and clocksource.
*/
void __init at91rm9200_timer_init(void)
{
/* For device tree enabled device: initialize here */
of_at91rm9200_st_init();
/* Disable all timer interrupts, and clear any pending ones */
at91_st_write(AT91_ST_IDR,
AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
at91_st_read(AT91_ST_SR);
/* Make IRQs happen for the system timer */
setup_irq(at91rm9200_timer_irq.irq, &at91rm9200_timer_irq);
/* The 32KiHz "Slow Clock" (tick every 30517.58 nanoseconds) is used
* directly for the clocksource and all clockevents, after adjusting
* its prescaler from the 1 Hz default.
*/
at91_st_write(AT91_ST_RTMR, 1);
/* Setup timer clockevent, with minimum of two ticks (important!!) */
clkevt.cpumask = cpumask_of(0);
clockevents_config_and_register(&clkevt, AT91_SLOW_CLOCK,
2, AT91_ST_ALMV);
/* register clocksource */
clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
}
static int
clkevt32k_next_event(unsigned long delta, struct clock_event_device *dev)
{
u32 alm;
int status = 0;
BUG_ON(delta < 2);
/* The alarm IRQ uses absolute time (now+delta), not the relative
* time (delta) in our calling convention. Like all clockevents
* using such "match" hardware, we have a race to defend against.
*
* Our defense here is to have set up the clockevent device so the
* delta is at least two. That way we never end up writing RTAR
* with the value then held in CRTR ... which would mean the match
* wouldn't trigger until 32 seconds later, after CRTR wraps.
*/
alm = read_CRTR();
/* Cancel any pending alarm; flush any pending IRQ */
at91_st_write(AT91_ST_RTAR, alm);
at91_st_read(AT91_ST_SR);
/* Schedule alarm by writing RTAR. */
alm += delta;
at91_st_write(AT91_ST_RTAR, alm);
return status;
}
static void
clkevt32k_mode(enum clock_event_mode mode, struct clock_event_device *dev)
{
/* Disable and flush pending timer interrupts */
at91_st_write(AT91_ST_IDR, AT91_ST_PITS | AT91_ST_ALMS);
at91_st_read(AT91_ST_SR);
last_crtr = read_CRTR();
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
/* PIT for periodic irqs; fixed rate of 1/HZ */
irqmask = AT91_ST_PITS;
at91_st_write(AT91_ST_PIMR, RM9200_TIMER_LATCH);
break;
case CLOCK_EVT_MODE_ONESHOT:
/* ALM for oneshot irqs, set by next_event()
* before 32 seconds have passed
*/
irqmask = AT91_ST_ALMS;
at91_st_write(AT91_ST_RTAR, last_crtr);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
irqmask = 0;
break;
}
at91_st_write(AT91_ST_IER, irqmask);
}
/*
* ST (system timer) module supports both clockevents and clocksource.
*/
void __init at91rm9200_timer_init(void)
{
/* Disable all timer interrupts, and clear any pending ones */
at91_st_write(AT91_ST_IDR,
AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
at91_st_read(AT91_ST_SR);
/* Make IRQs happen for the system timer */
setup_irq(AT91_ID_SYS, &at91rm9200_timer_irq);
/* The 32KiHz "Slow Clock" (tick every 30517.58 nanoseconds) is used
* directly for the clocksource and all clockevents, after adjusting
* its prescaler from the 1 Hz default.
*/
at91_st_write(AT91_ST_RTMR, 1);
/* Setup timer clockevent, with minimum of two ticks (important!!) */
clkevt.mult = div_sc(AT91_SLOW_CLOCK, NSEC_PER_SEC, clkevt.shift);
clkevt.max_delta_ns = clockevent_delta2ns(AT91_ST_ALMV, &clkevt);
clkevt.min_delta_ns = clockevent_delta2ns(2, &clkevt) + 1;
clkevt.cpumask = cpumask_of(0);
clockevents_register_device(&clkevt);
/* register clocksource */
clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
}
static int
clkevt32k_next_event(unsigned long delta, struct clock_event_device *dev)
{
u32 alm;
int status = 0;
BUG_ON(delta < 2);
alm = read_CRTR();
at91_st_write(AT91_ST_RTAR, alm);
at91_st_read(AT91_ST_SR);
alm += delta;
at91_st_write(AT91_ST_RTAR, alm);
return status;
}
void __init at91rm9200_timer_init(void)
{
at91_st_write(AT91_ST_IDR,
AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
at91_st_read(AT91_ST_SR);
setup_irq(AT91_ID_SYS, &at91rm9200_timer_irq);
at91_st_write(AT91_ST_RTMR, 1);
clkevt.mult = div_sc(AT91_SLOW_CLOCK, NSEC_PER_SEC, clkevt.shift);
clkevt.max_delta_ns = clockevent_delta2ns(AT91_ST_ALMV, &clkevt);
clkevt.min_delta_ns = clockevent_delta2ns(2, &clkevt) + 1;
clkevt.cpumask = cpumask_of(0);
clockevents_register_device(&clkevt);
clocksource_register_hz(&clk32k, AT91_SLOW_CLOCK);
}
