minix/kernel/arch/i386/clock.c
Kees van Reeuwijk a701e290f7 Removed unused symbols.
Made some functions PRIVATE, including ones that aren't used anywhere.
2010-01-25 18:13:48 +00:00

121 lines
3.2 KiB
C

/* i386-specific clock functions. */
#include <ibm/ports.h>
#include <minix/portio.h>
#include "../../kernel.h"
#include "../../clock.h"
#ifdef CONFIG_APIC
#include "apic.h"
#endif
#define CLOCK_ACK_BIT 0x80 /* PS/2 clock interrupt acknowledge bit */
/* Clock parameters. */
#define COUNTER_FREQ (2*TIMER_FREQ) /* counter frequency using square wave */
#define LATCH_COUNT 0x00 /* cc00xxxx, c = channel, x = any */
#define SQUARE_WAVE 0x36 /* ccaammmb, a = access, m = mode, b = BCD */
/* 11x11, 11 = LSB then MSB, x11 = sq wave */
#define TIMER_FREQ 1193182 /* clock frequency for timer in PC and AT */
#define TIMER_COUNT(freq) (TIMER_FREQ/(freq)) /* initial value for counter*/
PRIVATE irq_hook_t pic_timer_hook; /* interrupt handler hook */
/*===========================================================================*
* init_8235A_timer *
*===========================================================================*/
PUBLIC int init_8253A_timer(unsigned freq)
{
/* Initialize channel 0 of the 8253A timer to, e.g., 60 Hz,
* and register the CLOCK task's interrupt handler to be run
* on every clock tick.
*/
outb(TIMER_MODE, SQUARE_WAVE); /* run continuously */
outb(TIMER0, (TIMER_COUNT(freq) & 0xff)); /* timer low byte */
outb(TIMER0, TIMER_COUNT(freq) >> 8); /* timer high byte */
return OK;
}
/*===========================================================================*
* stop_8235A_timer *
*===========================================================================*/
PUBLIC void stop_8253A_timer(void)
{
/* Reset the clock to the BIOS rate. (For rebooting.) */
outb(TIMER_MODE, 0x36);
outb(TIMER0, 0);
outb(TIMER0, 0);
}
/*===========================================================================*
* read_8235A_timer *
*===========================================================================*/
PRIVATE clock_t read_8253A_timer(void)
{
/* Read the counter of channel 0 of the 8253A timer. This counter
* counts down at a rate of TIMER_FREQ and restarts at
* TIMER_COUNT-1 when it reaches zero. A hardware interrupt
* (clock tick) occurs when the counter gets to zero and restarts
* its cycle.
*/
u32_t count;
outb(TIMER_MODE, LATCH_COUNT);
count = inb(TIMER0);
count |= (inb(TIMER0) << 8);
return count;
}
PUBLIC int arch_init_local_timer(unsigned freq)
{
#ifdef CONFIG_APIC
/* if we know the address, lapic is enabled and we should use it */
if (lapic_addr) {
lapic_set_timer_periodic(freq);
} else
{
BOOT_VERBOSE(kprintf("Initiating legacy i8253 timer\n"));
#else
{
#endif
init_8253A_timer(freq);
}
return 0;
}
PUBLIC void arch_stop_local_timer(void)
{
#ifdef CONFIG_APIC
if (lapic_addr) {
lapic_stop_timer();
} else
#endif
{
stop_8253A_timer();
}
}
PUBLIC int arch_register_local_timer_handler(irq_handler_t handler)
{
#ifdef CONFIG_APIC
if (lapic_addr) {
/* Using APIC, it is configured in apic_idt_init() */
BOOT_VERBOSE(kprintf("Using LAPIC timer as tick source\n"));
} else
#endif
{
/* Using PIC, Initialize the CLOCK's interrupt hook. */
pic_timer_hook.proc_nr_e = NONE;
pic_timer_hook.irq = CLOCK_IRQ;
put_irq_handler(&pic_timer_hook, CLOCK_IRQ, handler);
}
return 0;
}