diff options
Diffstat (limited to 'arch/i386/kernel/i8253.c')
| -rw-r--r-- | arch/i386/kernel/i8253.c | 96 |
1 files changed, 88 insertions, 8 deletions
diff --git a/arch/i386/kernel/i8253.c b/arch/i386/kernel/i8253.c index 9a0060b92e3..a6bc7bb3883 100644 --- a/arch/i386/kernel/i8253.c +++ b/arch/i386/kernel/i8253.c @@ -2,7 +2,7 @@ * i8253.c 8253/PIT functions * */ -#include <linux/clocksource.h> +#include <linux/clockchips.h> #include <linux/spinlock.h> #include <linux/jiffies.h> #include <linux/sysdev.h> @@ -19,17 +19,97 @@ DEFINE_SPINLOCK(i8253_lock); EXPORT_SYMBOL(i8253_lock); -void setup_pit_timer(void) +/* + * HPET replaces the PIT, when enabled. So we need to know, which of + * the two timers is used + */ +struct clock_event_device *global_clock_event; + +/* + * Initialize the PIT timer. + * + * This is also called after resume to bring the PIT into operation again. + */ +static void init_pit_timer(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + unsigned long flags; + + spin_lock_irqsave(&i8253_lock, flags); + + switch(mode) { + case CLOCK_EVT_MODE_PERIODIC: + /* binary, mode 2, LSB/MSB, ch 0 */ + outb_p(0x34, PIT_MODE); + udelay(10); + outb_p(LATCH & 0xff , PIT_CH0); /* LSB */ + udelay(10); + outb(LATCH >> 8 , PIT_CH0); /* MSB */ + break; + + case CLOCK_EVT_MODE_ONESHOT: + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + /* One shot setup */ + outb_p(0x38, PIT_MODE); + udelay(10); + break; + } + spin_unlock_irqrestore(&i8253_lock, flags); +} + +/* + * Program the next event in oneshot mode + * + * Delta is given in PIT ticks + */ +static int pit_next_event(unsigned long delta, struct clock_event_device *evt) { unsigned long flags; spin_lock_irqsave(&i8253_lock, flags); - outb_p(0x34,PIT_MODE); /* binary, mode 2, LSB/MSB, ch 0 */ - udelay(10); - outb_p(LATCH & 0xff , PIT_CH0); /* LSB */ - udelay(10); - outb(LATCH >> 8 , PIT_CH0); /* MSB */ + outb_p(delta & 0xff , PIT_CH0); /* LSB */ + outb(delta >> 8 , PIT_CH0); /* MSB */ spin_unlock_irqrestore(&i8253_lock, flags); + + return 0; +} + +/* + * On UP the PIT can serve all of the possible timer functions. On SMP systems + * it can be solely used for the global tick. + * + * The profiling and update capabilites are switched off once the local apic is + * registered. This mechanism replaces the previous #ifdef LOCAL_APIC - + * !using_apic_timer decisions in do_timer_interrupt_hook() + */ +struct clock_event_device pit_clockevent = { + .name = "pit", + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_mode = init_pit_timer, + .set_next_event = pit_next_event, + .shift = 32, + .irq = 0, +}; + +/* + * Initialize the conversion factor and the min/max deltas of the clock event + * structure and register the clock event source with the framework. + */ +void __init setup_pit_timer(void) +{ + /* + * Start pit with the boot cpu mask and make it global after the + * IO_APIC has been initialized. + */ + pit_clockevent.cpumask = cpumask_of_cpu(0); + pit_clockevent.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, 32); + pit_clockevent.max_delta_ns = + clockevent_delta2ns(0x7FFF, &pit_clockevent); + pit_clockevent.min_delta_ns = + clockevent_delta2ns(0xF, &pit_clockevent); + clockevents_register_device(&pit_clockevent); + global_clock_event = &pit_clockevent; } /* @@ -46,7 +126,7 @@ static cycle_t pit_read(void) static u32 old_jifs; spin_lock_irqsave(&i8253_lock, flags); - /* + /* * Although our caller may have the read side of xtime_lock, * this is now a seqlock, and we are cheating in this routine * by having side effects on state that we cannot undo if |