diff options
author | Mikael Pettersson <mikpe@it.uu.se> | 2009-10-29 11:46:54 -0700 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2009-10-29 11:46:54 -0700 |
commit | 469d30448dad13600cdd246024f9db8e80614c45 (patch) | |
tree | a610e9dd4b40dd540376eba7aaaed2538298f828 /arch/arm/plat-iop | |
parent | a91549a8f27e63e0e537fe1c20d4845581de894f (diff) | |
download | talos-op-linux-469d30448dad13600cdd246024f9db8e80614c45.tar.gz talos-op-linux-469d30448dad13600cdd246024f9db8e80614c45.zip |
iop: clockevent support
This updates the IOP platform to expose the interrupting
timer 0 as a clockevent object. The timer interrupt handler
is changed to call the clockevent ->event_handler() instead
of timer_tick(), and ->set_next_event() and ->set_mode()
operations are added to allow the mode of the timer to be
updated (required for ONESHOT/NOHZ mode).
Timer 0 must now be properly initialised, which requires
a new write_tcr0() function from the mach-specific code.
The mode of timer 0 must be read at the start of ->set_mode(),
which requires a new read_tmr0() function from the mach-
specific code.
Initial setup of timer 0 is also rewritten to be more robust.
Tested on n2100, compile-tested for all plat-iop machines.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'arch/arm/plat-iop')
-rw-r--r-- | arch/arm/plat-iop/time.c | 101 |
1 files changed, 90 insertions, 11 deletions
diff --git a/arch/arm/plat-iop/time.c b/arch/arm/plat-iop/time.c index 5506c9b45612..a550e96394ab 100644 --- a/arch/arm/plat-iop/time.c +++ b/arch/arm/plat-iop/time.c @@ -20,6 +20,7 @@ #include <linux/timex.h> #include <linux/io.h> #include <linux/clocksource.h> +#include <linux/clockchips.h> #include <mach/hardware.h> #include <asm/irq.h> #include <asm/uaccess.h> @@ -64,7 +65,81 @@ static void __init iop_clocksource_set_hz(struct clocksource *cs, unsigned int h cs->name, cs->shift, cs->mult); } +/* + * IOP clockevents (interrupting timer 0). + */ +static int iop_set_next_event(unsigned long delta, + struct clock_event_device *unused) +{ + u32 tmr = IOP_TMR_PRIVILEGED | IOP_TMR_RATIO_1_1; + + BUG_ON(delta == 0); + write_tmr0(tmr & ~(IOP_TMR_EN | IOP_TMR_RELOAD)); + write_tcr0(delta); + write_tmr0((tmr & ~IOP_TMR_RELOAD) | IOP_TMR_EN); + + return 0; +} + static unsigned long ticks_per_jiffy; + +static void iop_set_mode(enum clock_event_mode mode, + struct clock_event_device *unused) +{ + u32 tmr = read_tmr0(); + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + write_tmr0(tmr & ~IOP_TMR_EN); + write_tcr0(ticks_per_jiffy - 1); + tmr |= (IOP_TMR_RELOAD | IOP_TMR_EN); + break; + case CLOCK_EVT_MODE_ONESHOT: + /* ->set_next_event sets period and enables timer */ + tmr &= ~(IOP_TMR_RELOAD | IOP_TMR_EN); + break; + case CLOCK_EVT_MODE_RESUME: + tmr |= IOP_TMR_EN; + break; + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + default: + tmr &= ~IOP_TMR_EN; + break; + } + + write_tmr0(tmr); +} + +static struct clock_event_device iop_clockevent = { + .name = "iop_timer0", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .rating = 300, + .set_next_event = iop_set_next_event, + .set_mode = iop_set_mode, +}; + +static void __init iop_clockevent_set_hz(struct clock_event_device *ce, unsigned int hz) +{ + u64 temp; + u32 shift; + + /* Find shift and mult values for hz. */ + shift = 32; + do { + temp = (u64) hz << shift; + do_div(temp, NSEC_PER_SEC); + if ((temp >> 32) == 0) + break; + } while (--shift != 0); + + ce->shift = shift; + ce->mult = (u32) temp; + + printk(KERN_INFO "clockevent: %s uses shift %u mult %#lx\n", + ce->name, ce->shift, ce->mult); +} + static unsigned long ticks_per_usec; static unsigned long next_jiffy_time; @@ -95,14 +170,10 @@ unsigned long iop_gettimeoffset(void) static irqreturn_t iop_timer_interrupt(int irq, void *dev_id) { - write_tisr(1); - - while ((signed long)(next_jiffy_time - read_tcr1()) - >= ticks_per_jiffy) { - timer_tick(); - next_jiffy_time -= ticks_per_jiffy; - } + struct clock_event_device *evt = dev_id; + write_tisr(1); + evt->event_handler(evt); return IRQ_HANDLED; } @@ -110,6 +181,7 @@ static struct irqaction iop_timer_irq = { .name = "IOP Timer Tick", .handler = iop_timer_interrupt, .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL, + .dev_id = &iop_clockevent, }; static unsigned long iop_tick_rate; @@ -132,10 +204,19 @@ void __init iop_init_time(unsigned long tick_rate) IOP_TMR_RELOAD | IOP_TMR_RATIO_1_1; /* - * We use timer 0 for our timer interrupt, and timer 1 as - * monotonic counter for tracking missed jiffies. + * Set up interrupting clockevent timer 0. */ + write_tmr0(timer_ctl & ~IOP_TMR_EN); + setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq); + iop_clockevent_set_hz(&iop_clockevent, tick_rate); + iop_clockevent.max_delta_ns = + clockevent_delta2ns(0xfffffffe, &iop_clockevent); + iop_clockevent.min_delta_ns = + clockevent_delta2ns(0xf, &iop_clockevent); + iop_clockevent.cpumask = cpumask_of(0); + clockevents_register_device(&iop_clockevent); write_trr0(ticks_per_jiffy - 1); + write_tcr0(ticks_per_jiffy - 1); write_tmr0(timer_ctl); /* @@ -146,6 +227,4 @@ void __init iop_init_time(unsigned long tick_rate) write_tmr1(timer_ctl); iop_clocksource_set_hz(&iop_clocksource, tick_rate); clocksource_register(&iop_clocksource); - - setup_irq(IRQ_IOP_TIMER0, &iop_timer_irq); } |