nuclear@33: #include <stdio.h>
nuclear@37: #include <time.h>
nuclear@33: #include "intr.h"
nuclear@33: #include "asmops.h"
nuclear@34: #include "timer.h"
nuclear@51: #include "proc.h"
nuclear@51: #include "sched.h"
nuclear@33: #include "config.h"
nuclear@33: 
nuclear@33: /* frequency of the oscillator driving the 8254 timer */
nuclear@33: #define OSC_FREQ_HZ		1193182
nuclear@33: 
nuclear@33: /* macro to divide and round to the nearest integer */
nuclear@33: #define DIV_ROUND(a, b) ((a) / (b) + ((a) % (b)) / ((b) / 2))
nuclear@33: 
nuclear@33: /* I/O ports connected to the 8254 */
nuclear@33: #define PORT_DATA0	0x40
nuclear@33: #define PORT_DATA1	0x41
nuclear@33: #define PORT_DATA2	0x42
nuclear@33: #define PORT_CMD	0x43
nuclear@33: 
nuclear@33: /* command bits */
nuclear@33: #define CMD_CHAN0			0
nuclear@33: #define CMD_CHAN1			(1 << 6)
nuclear@33: #define CMD_CHAN2			(2 << 6)
nuclear@33: #define CMD_RDBACK			(3 << 6)
nuclear@33: 
nuclear@33: #define CMD_LATCH			0
nuclear@33: #define CMD_ACCESS_LOW		(1 << 4)
nuclear@33: #define CMD_ACCESS_HIGH		(2 << 4)
nuclear@33: #define CMD_ACCESS_BOTH		(3 << 4)
nuclear@33: 
nuclear@33: #define CMD_OP_INT_TERM		0
nuclear@33: #define CMD_OP_ONESHOT		(1 << 1)
nuclear@33: #define CMD_OP_RATE			(2 << 1)
nuclear@33: #define CMD_OP_SQWAVE		(3 << 1)
nuclear@33: #define CMD_OP_SOFT_STROBE	(4 << 1)
nuclear@33: #define CMD_OP_HW_STROBE	(5 << 1)
nuclear@33: 
nuclear@33: #define CMD_MODE_BIN		0
nuclear@33: #define CMD_MODE_BCD		1
nuclear@33: 
nuclear@33: 
nuclear@51: #define MSEC_TO_TICKS(ms)	((ms) * TICK_FREQ_HZ / 1000)
nuclear@51: 
nuclear@51: struct timer_event {
nuclear@51: 	int dt;	/* remaining ticks delta from the previous event */
nuclear@51: 	struct timer_event *next;
nuclear@51: };
nuclear@51: 
nuclear@51: 
nuclear@63: static void timer_handler();
nuclear@33: 
nuclear@33: 
nuclear@51: static struct timer_event *evlist;
nuclear@51: 
nuclear@51: 
nuclear@33: void init_timer(void)
nuclear@33: {
nuclear@34: 	/* calculate the reload count: round(osc / freq) */
nuclear@34: 	int reload_count = DIV_ROUND(OSC_FREQ_HZ, TICK_FREQ_HZ);
nuclear@33: 
nuclear@33: 	/* set the mode to square wave for channel 0, both low
nuclear@34: 	 * and high reload count bytes will follow...
nuclear@33: 	 */
nuclear@33: 	outb(CMD_CHAN0 | CMD_ACCESS_BOTH | CMD_OP_SQWAVE, PORT_CMD);
nuclear@33: 
nuclear@34: 	/* write the low and high bytes of the reload count to the
nuclear@33: 	 * port for channel 0
nuclear@33: 	 */
nuclear@34: 	outb(reload_count & 0xff, PORT_DATA0);
nuclear@34: 	outb((reload_count >> 8) & 0xff, PORT_DATA0);
nuclear@33: 
nuclear@33: 	/* set the timer interrupt handler */
nuclear@63: 	interrupt(IRQ_TO_INTR(0), timer_handler);
nuclear@33: }
nuclear@33: 
nuclear@55: void sleep(unsigned long msec)
nuclear@51: {
nuclear@51: 	int ticks, tsum, istate;
nuclear@51: 	struct timer_event *ev, *node;
nuclear@51: 
nuclear@55: 	printf("sleep(%lu)\n", msec);
nuclear@51: 
nuclear@51: 	if((ticks = MSEC_TO_TICKS(msec)) <= 0) {
nuclear@55: 		return;
nuclear@51: 	}
nuclear@51: 
nuclear@51: 	if(!(ev = malloc(sizeof *ev))) {
nuclear@55: 		printf("sleep: failed to allocate timer_event structure\n");
nuclear@55: 		return;
nuclear@51: 	}
nuclear@51: 
nuclear@51: 	istate = get_intr_state();
nuclear@51: 	disable_intr();
nuclear@51: 
nuclear@51: 	/* insert at the beginning */
nuclear@51: 	if(!evlist || ticks <= evlist->dt) {
nuclear@51: 		ev->next = evlist;
nuclear@51: 		evlist = ev;
nuclear@51: 
nuclear@51: 		ev->dt = ticks;
nuclear@51: 		if(ev->next) {
nuclear@51: 			ev->next->dt -= ticks;
nuclear@51: 		}
nuclear@55: 	} else {
nuclear@51: 
nuclear@55: 		tsum = evlist->dt;
nuclear@55: 		node = evlist;
nuclear@51: 
nuclear@55: 		while(node->next && ticks > tsum + node->next->dt) {
nuclear@55: 			tsum += node->next->dt;
nuclear@55: 			node = node->next;
nuclear@55: 		}
nuclear@51: 
nuclear@55: 		ev->next = node->next;
nuclear@55: 		node->next = ev;
nuclear@51: 
nuclear@55: 		/* fix the relative times */
nuclear@55: 		ev->dt = ticks - tsum;
nuclear@55: 		if(ev->next) {
nuclear@55: 			ev->next->dt -= ev->dt;
nuclear@55: 		}
nuclear@51: 	}
nuclear@51: 
nuclear@51: 	set_intr_state(istate);
nuclear@55: 
nuclear@55: 	/* wait on the address of this timer event */
nuclear@55: 	wait(ev);
nuclear@51: }
nuclear@51: 
nuclear@33: /* This will be called by the interrupt dispatcher approximately
nuclear@33:  * every 1/250th of a second, so it must be extremely fast.
nuclear@33:  * For now, just increasing a tick counter will suffice.
nuclear@33:  */
nuclear@63: static void timer_handler(int inum)
nuclear@33: {
nuclear@51: 	int istate;
nuclear@57: 	struct process *p;
nuclear@51: 
nuclear@33: 	nticks++;
nuclear@51: 
nuclear@56: 	/*printf("TICKS: %d\n", nticks);*/
nuclear@51: 
nuclear@51: 	istate = get_intr_state();
nuclear@51: 	disable_intr();
nuclear@51: 
nuclear@51: 	/* find out if there are any timers that have to go off */
nuclear@51: 	if(evlist) {
nuclear@51: 		evlist->dt--;
nuclear@51: 
nuclear@56: 		while(evlist && evlist->dt <= 0) {
nuclear@51: 			struct timer_event *ev = evlist;
nuclear@51: 			evlist = evlist->next;
nuclear@51: 
nuclear@51: 			printf("timer going off!!!\n");
nuclear@55: 			/* wake up all processes waiting on this address */
nuclear@55: 			wakeup(ev);
nuclear@51: 			free(ev);
nuclear@51: 		}
nuclear@51: 	}
nuclear@51: 
nuclear@57: 	/* decrement the process' ticks_left and call the scheduler to decide if
nuclear@57: 	 * it's time to switch processes
nuclear@57: 	 */
nuclear@57: 	if((p = get_current_proc())) {
nuclear@57: 		p->ticks_left--;
nuclear@57: 	}
nuclear@56: 	schedule();
nuclear@51: 
nuclear@51: 	set_intr_state(istate);
nuclear@33: }