diff options
| -rw-r--r-- | drivers/clocksource/Kconfig | 5 | ||||
| -rw-r--r-- | drivers/clocksource/i8253.c | 101 | ||||
| -rw-r--r-- | include/linux/i8253.h | 2 |
3 files changed, 100 insertions, 8 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 330343bcb67e..d8d3e02b912c 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -1,11 +1,14 @@ config CLKSRC_I8253 bool +config CLKEVT_I8253 + bool + config I8253_LOCK bool config CLKBLD_I8253 - def_bool y if CLKSRC_I8253 || I8253_LOCK + def_bool y if CLKSRC_I8253 || CLKEVT_I8253 || I8253_LOCK config CLKSRC_MMIO bool diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c index e594f52eb88e..27c49e60b7d6 100644 --- a/drivers/clocksource/i8253.c +++ b/drivers/clocksource/i8253.c @@ -1,13 +1,14 @@ /* * i8253 PIT clocksource */ -#include <linux/clocksource.h> +#include <linux/clockchips.h> #include <linux/init.h> #include <linux/io.h> #include <linux/spinlock.h> #include <linux/timex.h> #include <linux/module.h> #include <linux/i8253.h> +#include <linux/smp.h> /* * Protects access to I/O ports @@ -47,15 +48,15 @@ static cycle_t i8253_read(struct clocksource *cs) * 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; + outb_p(0x00, PIT_MODE); /* latch the count ASAP */ + count = inb_p(PIT_CH0); /* read the latched count */ + count |= inb_p(PIT_CH0) << 8; /* VIA686a test code... reset the latch if count > max + 1 */ if (count > LATCH) { - outb_pit(0x34, PIT_MODE); - outb_pit(PIT_LATCH & 0xff, PIT_CH0); - outb_pit(PIT_LATCH >> 8, PIT_CH0); + outb_p(0x34, PIT_MODE); + outb_p(PIT_LATCH & 0xff, PIT_CH0); + outb_p(PIT_LATCH >> 8, PIT_CH0); count = PIT_LATCH - 1; } @@ -97,3 +98,89 @@ int __init clocksource_i8253_init(void) return clocksource_register_hz(&i8253_cs, PIT_TICK_RATE); } #endif + +#ifdef CONFIG_CLKEVT_I8253 +/* + * 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_p(0x34, PIT_MODE); + outb_p(LATCH & 0xff , PIT_CH0); /* LSB */ + outb_p(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); + } + break; + + case CLOCK_EVT_MODE_ONESHOT: + /* One shot setup */ + outb_p(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_p(delta & 0xff , PIT_CH0); /* LSB */ + outb_p(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. + */ +struct clock_event_device i8253_clockevent = { + .name = "pit", + .features = CLOCK_EVT_FEAT_PERIODIC, + .set_mode = init_pit_timer, + .set_next_event = pit_next_event, +}; + +/* + * 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 clockevent_i8253_init(bool oneshot) +{ + if (oneshot) + i8253_clockevent.features |= CLOCK_EVT_FEAT_ONESHOT; + /* + * Start pit with the boot cpu mask. x86 might make it global + * when it is used as broadcast device later. + */ + i8253_clockevent.cpumask = cpumask_of(smp_processor_id()); + + clockevents_config_and_register(&i8253_clockevent, PIT_TICK_RATE, + 0xF, 0x7FFF); +} +#endif diff --git a/include/linux/i8253.h b/include/linux/i8253.h index 76039c86ab58..487d50c7db39 100644 --- a/include/linux/i8253.h +++ b/include/linux/i8253.h @@ -24,6 +24,8 @@ #define outb_pit outb_p extern raw_spinlock_t i8253_lock; +extern struct clock_event_device i8253_clockevent; +extern void clockevent_i8253_init(bool oneshot); extern void setup_pit_timer(void); |