timer.c

#include <timer.h>
#include <gic.h>

static void do_timer4(void)
{
	u32 val;

	val = ioread32(TINT_CSTAT);
	if (val & (1 << 9)) {
		printf("auto change display pic...\n");
	}	 

	iowrite32(val, TINT_CSTAT);
}

void timer4_init(u32 periodms)
{
	u32 val;

	/*对于TIMER2, TIMER3, TIMER4第一级分频后的频率为1MHz*/
	val = ioread32(TCFG0);
	val &= ~(0xff << 8);
	val |= (99 << 8);
	iowrite32(val, TCFG0);
	/*第二级分频后的频率为1MHz*/
	val = ioread32(TCFG1);
	val &= ~(0xf << 16);
	iowrite32(val, TCFG1);

	// f = 1000000HZ, T=1/f = 1us = 0.001ms;
	iowrite32(periodms*1000, TCNTB4);

	val = ioread32(TCON);
	val &= ~(0x7 << 20);
	iowrite32(val, TCON);

	/*将TCNTB4里的值更新进逻辑单元*/
	val = ioread32(TCON);
	val |= (1 << 21) | (1 << 22); 
	iowrite32(val, TCON);

	val = ioread32(TCON);
	val &= ~(1 << 21);
	iowrite32(val, TCON);

	/*启动timer4工作和设置自动加载功能*/
	val = ioread32(TCON);
	val |= (1 << 20);
	iowrite32(val, TCON);
	
	/*使能timer4中断*/
	val = ioread32(TINT_CSTAT);
	val |= 1 << 4;
	iowrite32(val, TINT_CSTAT);
#define TIMER4ID 73
	irq_request_cpu0(TIMER4ID, do_timer4, 0);	
}

void timer0_init(u32 periodus, u32 dutyus)
{
	u32 val;

	/*第一级分频后的频率为1MHz*/
	val = ioread32(TCFG0);
	val &= ~0xff;
	val |= 99;
	iowrite32(val, TCFG0);
	/*第二级分频后的频率为1MHz*/
	val = ioread32(TCFG1);
	val &= ~0xf;
	iowrite32(val, TCFG1);

	// f = 1000000HZ, T=1/f = 1us;
	iowrite32(periodus, TCNTB0);
	iowrite32(periodus - dutyus, TCMPB0);

	val = ioread32(TCON);
	val &= ~0xf;
	iowrite32(val, TCON);

	/*将TCNTB0和TCMPB0里的值更新进逻辑单元*/
	val = ioread32(TCON);
	val |= (1 << 3) | (1 << 1); 
	iowrite32(val, TCON);

	val = ioread32(TCON);
	val &= ~(1 << 1);
	iowrite32(val, TCON);

	/*启动timer4工作和设置自动加载功能*/
	val = ioread32(TCON);
	val |= (1 << 0);
	iowrite32(val, TCON);
}

void beep_set_hz(u32 freq)
{
#define USPERSEC 1000000UL
	u32 tmp = USPERSEC/freq;
	u32 val;

	/*设置GPD0的0引脚为TOU0*/
	val = ioread32(GPD0CON);
	val &= ~0xf;
	val |= 0x2;
	iowrite32(val, GPD0CON);

	timer0_init(tmp, tmp >> 1);
}