diff options
Diffstat (limited to 'arch/x86/kernel/i8253.c')
| -rw-r--r-- | arch/x86/kernel/i8253.c | 183 |
1 files changed, 6 insertions, 177 deletions
diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c index 2dfd3159744..f2b96de3c7c 100644 --- a/arch/x86/kernel/i8253.c +++ b/arch/x86/kernel/i8253.c @@ -3,195 +3,27 @@ * */ #include <linux/clockchips.h> -#include <linux/interrupt.h> -#include <linux/spinlock.h> -#include <linux/jiffies.h> #include <linux/module.h> #include <linux/timex.h> -#include <linux/delay.h> -#include <linux/init.h> -#include <linux/io.h> +#include <linux/i8253.h> -#include <asm/i8253.h> #include <asm/hpet.h> +#include <asm/time.h> #include <asm/smp.h> -DEFINE_RAW_SPINLOCK(i8253_lock); -EXPORT_SYMBOL(i8253_lock); - /* * 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) -{ - raw_spin_lock(&i8253_lock); - - switch (mode) { - case CLOCK_EVT_MODE_PERIODIC: - /* binary, mode 2, LSB/MSB, ch 0 */ - outb_pit(0x34, PIT_MODE); - outb_pit(LATCH & 0xff , PIT_CH0); /* LSB */ - outb_pit(LATCH >> 8 , PIT_CH0); /* MSB */ - break; - - case CLOCK_EVT_MODE_SHUTDOWN: - case CLOCK_EVT_MODE_UNUSED: - if (evt->mode == CLOCK_EVT_MODE_PERIODIC || - evt->mode == CLOCK_EVT_MODE_ONESHOT) { - outb_pit(0x30, PIT_MODE); - outb_pit(0, PIT_CH0); - outb_pit(0, PIT_CH0); - } - break; - - case CLOCK_EVT_MODE_ONESHOT: - /* One shot setup */ - outb_pit(0x38, PIT_MODE); - break; - - case CLOCK_EVT_MODE_RESUME: - /* Nothing to do here */ - break; - } - raw_spin_unlock(&i8253_lock); -} - -/* - * 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) -{ - raw_spin_lock(&i8253_lock); - outb_pit(delta & 0xff , PIT_CH0); /* LSB */ - outb_pit(delta >> 8 , PIT_CH0); /* MSB */ - raw_spin_unlock(&i8253_lock); - - 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 capabilities 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() - */ -static struct clock_event_device pit_ce = { - .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_ce.cpumask = cpumask_of(smp_processor_id()); - pit_ce.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, pit_ce.shift); - pit_ce.max_delta_ns = clockevent_delta2ns(0x7FFF, &pit_ce); - pit_ce.min_delta_ns = clockevent_delta2ns(0xF, &pit_ce); - - clockevents_register_device(&pit_ce); - global_clock_event = &pit_ce; + clockevent_i8253_init(true); + global_clock_event = &i8253_clockevent; } #ifndef CONFIG_X86_64 -/* - * Since the PIT overflows every tick, its not very useful - * to just read by itself. So use jiffies to emulate a free - * running counter: - */ -static cycle_t pit_read(struct clocksource *cs) -{ - static int old_count; - static u32 old_jifs; - unsigned long flags; - int count; - u32 jifs; - - raw_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 - * there is a collision on the seqlock and our caller has to - * retry. (Namely, old_jifs and old_count.) So we must treat - * jiffies as volatile despite the lock. We read jiffies - * before latching the timer count to guarantee that although - * the jiffies value might be older than the count (that is, - * the counter may underflow between the last point where - * jiffies was incremented and the point where we latch the - * count), it cannot be newer. - */ - jifs = jiffies; - outb_pit(0x00, PIT_MODE); /* latch the count ASAP */ - count = inb_pit(PIT_CH0); /* read the latched count */ - count |= inb_pit(PIT_CH0) << 8; - - /* VIA686a test code... reset the latch if count > max + 1 */ - if (count > LATCH) { - outb_pit(0x34, PIT_MODE); - outb_pit(LATCH & 0xff, PIT_CH0); - outb_pit(LATCH >> 8, PIT_CH0); - count = LATCH - 1; - } - - /* - * It's possible for count to appear to go the wrong way for a - * couple of reasons: - * - * 1. The timer counter underflows, but we haven't handled the - * resulting interrupt and incremented jiffies yet. - * 2. Hardware problem with the timer, not giving us continuous time, - * the counter does small "jumps" upwards on some Pentium systems, - * (see c't 95/10 page 335 for Neptun bug.) - * - * Previous attempts to handle these cases intelligently were - * buggy, so we just do the simple thing now. - */ - if (count > old_count && jifs == old_jifs) - count = old_count; - - old_count = count; - old_jifs = jifs; - - raw_spin_unlock_irqrestore(&i8253_lock, flags); - - count = (LATCH - 1) - count; - - return (cycle_t)(jifs * LATCH) + count; -} - -static struct clocksource pit_cs = { - .name = "pit", - .rating = 110, - .read = pit_read, - .mask = CLOCKSOURCE_MASK(32), - .mult = 0, - .shift = 20, -}; - static int __init init_pit_clocksource(void) { /* @@ -202,13 +34,10 @@ static int __init init_pit_clocksource(void) * - when local APIC timer is active (PIT is switched off) */ if (num_possible_cpus() > 1 || is_hpet_enabled() || - pit_ce.mode != CLOCK_EVT_MODE_PERIODIC) + i8253_clockevent.mode != CLOCK_EVT_MODE_PERIODIC) return 0; - pit_cs.mult = clocksource_hz2mult(CLOCK_TICK_RATE, pit_cs.shift); - - return clocksource_register(&pit_cs); + return clocksource_i8253_init(); } arch_initcall(init_pit_clocksource); - #endif /* !CONFIG_X86_64 */ |