diff options
Diffstat (limited to 'arch/x86/kernel/i8253.c')
| -rw-r--r-- | arch/x86/kernel/i8253.c | 72 |
1 files changed, 48 insertions, 24 deletions
diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c index a42c80745325..ef62b07b2b48 100644 --- a/arch/x86/kernel/i8253.c +++ b/arch/x86/kernel/i8253.c @@ -13,10 +13,17 @@ #include <asm/delay.h> #include <asm/i8253.h> #include <asm/io.h> +#include <asm/hpet.h> DEFINE_SPINLOCK(i8253_lock); EXPORT_SYMBOL(i8253_lock); +#ifdef CONFIG_X86_32 +static void pit_disable_clocksource(void); +#else +static inline void pit_disable_clocksource(void) { } +#endif + /* * HPET replaces the PIT, when enabled. So we need to know, which of * the two timers is used @@ -31,38 +38,38 @@ struct clock_event_device *global_clock_event; static void init_pit_timer(enum clock_event_mode mode, struct clock_event_device *evt) { - unsigned long flags; - - spin_lock_irqsave(&i8253_lock, flags); + spin_lock(&i8253_lock); switch(mode) { case CLOCK_EVT_MODE_PERIODIC: /* binary, mode 2, LSB/MSB, ch 0 */ - outb_p(0x34, PIT_MODE); - outb_p(LATCH & 0xff , PIT_CH0); /* LSB */ - outb(LATCH >> 8 , PIT_CH0); /* MSB */ + 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_p(0x30, PIT_MODE); - outb_p(0, PIT_CH0); - outb_p(0, PIT_CH0); + outb_pit(0x30, PIT_MODE); + outb_pit(0, PIT_CH0); + outb_pit(0, PIT_CH0); } + pit_disable_clocksource(); break; case CLOCK_EVT_MODE_ONESHOT: /* One shot setup */ - outb_p(0x38, PIT_MODE); + pit_disable_clocksource(); + outb_pit(0x38, PIT_MODE); break; case CLOCK_EVT_MODE_RESUME: /* Nothing to do here */ break; } - spin_unlock_irqrestore(&i8253_lock, flags); + spin_unlock(&i8253_lock); } /* @@ -72,12 +79,10 @@ static void init_pit_timer(enum clock_event_mode mode, */ static int pit_next_event(unsigned long delta, struct clock_event_device *evt) { - unsigned long flags; - - spin_lock_irqsave(&i8253_lock, flags); - outb_p(delta & 0xff , PIT_CH0); /* LSB */ - outb(delta >> 8 , PIT_CH0); /* MSB */ - spin_unlock_irqrestore(&i8253_lock, flags); + spin_lock(&i8253_lock); + outb_pit(delta & 0xff , PIT_CH0); /* LSB */ + outb_pit(delta >> 8 , PIT_CH0); /* MSB */ + spin_unlock(&i8253_lock); return 0; } @@ -148,15 +153,15 @@ static cycle_t pit_read(void) * count), it cannot be newer. */ jifs = jiffies; - outb_p(0x00, PIT_MODE); /* latch the count ASAP */ - count = inb_p(PIT_CH0); /* read the latched count */ - count |= inb_p(PIT_CH0) << 8; + 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_p(0x34, PIT_MODE); - outb_p(LATCH & 0xff, PIT_CH0); - outb(LATCH >> 8, PIT_CH0); + outb_pit(0x34, PIT_MODE); + outb_pit(LATCH & 0xff, PIT_CH0); + outb_pit(LATCH >> 8, PIT_CH0); count = LATCH - 1; } @@ -195,9 +200,28 @@ static struct clocksource clocksource_pit = { .shift = 20, }; +static void pit_disable_clocksource(void) +{ + /* + * Use mult to check whether it is registered or not + */ + if (clocksource_pit.mult) { + clocksource_unregister(&clocksource_pit); + clocksource_pit.mult = 0; + } +} + static int __init init_pit_clocksource(void) { - if (num_possible_cpus() > 1) /* PIT does not scale! */ + /* + * Several reasons not to register PIT as a clocksource: + * + * - On SMP PIT does not scale due to i8253_lock + * - when HPET is enabled + * - when local APIC timer is active (PIT is switched off) + */ + if (num_possible_cpus() > 1 || is_hpet_enabled() || + pit_clockevent.mode != CLOCK_EVT_MODE_PERIODIC) return 0; clocksource_pit.mult = clocksource_hz2mult(CLOCK_TICK_RATE, 20); |