我的开发板是TINY6410，现在做项目需要用到两路PWM波，但是开发板上两个PWM口都被占用了，所以想到用定时器来控制IO口，模拟实现PWM输出的功能。
我是参考
http://blog.csdn.net/gfocean/article/details/6245927这篇博客里的内容改动的。根据博客中的这篇文章，可以输出PWM波，但是在该博文中，在初始化部分即启动了定时器中断，所以在TINY6410一启动后，就输出了PWM波，这不是我想要的，所以根据这篇文章进行了修改，在ioctl函数中启动定时器，但是修改后，就不能输出PWM了。小弟新手，希望大侠能帮忙看看，不胜感激！代码如下：
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/hardware.h>
#include <plat/regs-timer.h>
#include <mach/regs-irq.h>
#include <asm/mach/time.h>
#include <linux/clk.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <mach/map.h>
#include <asm/ioctl.h>
#include <plat/gpio-cfg.h>
#include <mach/regs-clock.h>
#include <mach/regs-gpio.h>
#include <mach/gpio-bank-c.h> //IOPWM:GPC4
#include <linux/ioctl.h>
#include <linux/timer.h>
#include <linux/irq.h>
#define DEVICE_NAME "iopwm"
#define iopwm_irq IRQ_TIMER1
static struct semaphore lock1;
struct cdev *iopwm_cdev;
unsigned int counter=0;
unsigned int f=0;
//unsigned int pwm[]={110,55};
//unsigned int pwm=100;
//unsigned int duty=50;
unsigned long tmp;
static irqreturn_t iopwm_interrupt(int irq , void *dev_id)
{
if(irq !=IRQ_TIMER1){
printk("bad irq % d in timer0 /n", irq);
return -1;
}
// printk("good irq % d in timer0 /n", irq);
counter++;
if(counter ==1)
{
tmp = readl(S3C64XX_GPCDAT);
tmp |= (0x10);
writel(tmp, S3C64XX_GPCDAT);
}
if(counter ==2)
{
tmp = readl(S3C64XX_GPCDAT);
tmp &= ~(0x10);
writel(tmp, S3C64XX_GPCDAT);
counter=0;
}
return IRQ_RETVAL(IRQ_HANDLED);
}
void iopwm_timerinit(int freq)
{
unsigned long tcfg0,tcfg1,cstat;
struct clk *clk_p;
unsigned long pclk,tcnt;
//unsigned long freq=20000;
{
unsigned temp;
temp = readl(S3C64XX_GPCPUD);
temp = (temp & ~(0x3<<8))|(0x2<<8); //设置GPC4为上拉输出
writel(temp, S3C64XX_GPCPUD);
temp = readl(S3C64XX_GPCCON);
temp = (temp & ~(0xf<<16))|(0x1<<16); //23:20 0001
writel(temp, S3C64XX_GPCCON);
temp = readl(S3C64XX_GPCDAT);
temp |= (0x10);
writel(temp, S3C64XX_GPCDAT);
}
//tcon = __raw_readl(S3C_TCON);
tcfg1 = __raw_readl(S3C_TCFG1);
tcfg0 = __raw_readl(S3C_TCFG0);
//prescaler = 50
tcfg0 &= ~S3C_TCFG_PRESCALER0_MASK;
tcfg0 |= (50 - 1);
//mux = 1/16
tcfg1 &= ~S3C_TCFG1_MUX1_MASK;
tcfg1 |= S3C_TCFG1_MUX1_DIV16;
__raw_writel(tcfg1, S3C_TCFG1);
__raw_writel(tcfg0, S3C_TCFG0);
clk_p = clk_get(NULL, "pclk");
pclk = clk_get_rate(clk_p);
tcnt = (pclk/50/16)/freq;
printk("TCNT is %ld/n",tcnt);
__raw_writel(tcnt, S3C_TCNTB(1));
__raw_writel(0, S3C_TCMPB(1));
//¶šÊ±Æ÷1ÖжÏʹÄÜ
cstat = __raw_readl(S3C_TINT_CSTAT);
//cstat &=~S3C_TINT_CSTAT_T0INTEN;
cstat |=0x2;
__raw_writel(cstat,S3C_TINT_CSTAT);
printk("init iopwm success!\n");
}
void start_timer(void)
{
unsigned long tcon;
tcon = __raw_readl(S3C_TCON);
tcon &= ~0xf1<<4;
tcon |= 0xb<<8; //disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, start timer 1
__raw_writel(tcon, S3C_TCON);
tcon &= ~0x2<<8; //clear manual update bit
__raw_writel(tcon, S3C_TCON);
}
void stop_timer(void)
{
unsigned long tcon;
tcon = __raw_readl(S3C_TCON);
tcon &= ~0xf1<<4;
tcon |= 0xa<<8; //disable deadzone, auto-reload, inv-off, update TCNTB0&TCMPB0, stop timer 1
__raw_writel(tcon, S3C_TCON);
}
static int iopwm_open(struct inode *inode, struct file *file)
{
if (!down_trylock(&lock1))
return 0;
else
return -EBUSY;
}
static int iopwm_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned int arg)
{
switch (cmd)
{
case 1:
f=arg*2;
iopwm_timerinit(f);
stop_timer();
break;
case 0:
f=arg*2;
iopwm_timerinit(f);
start_timer();
break;
default:
return -EINVAL;
}
return 0;
}
static int iopwm_close(struct inode *inode,struct file *filp)
{
free_irq(iopwm_irq,NULL);
up(&lock1);
return 0;
}
static struct file_operations iopwm_fops={
.owner=THIS_MODULE,
.open=iopwm_open,
.unlocked_ioctl=iopwm_ioctl,
.release=iopwm_close,
};
static struct miscdevice misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DEVICE_NAME,
.fops = &iopwm_fops,
};
static int __init iopwm_init(void)
{
int ret;
init_MUTEX(&lock1);
ret = misc_register(&misc);
printk (DEVICE_NAME"\tinitialized\n");
iopwm_timerinit(1000);
stop_timer();
ret=request_irq(iopwm_irq,iopwm_interrupt,IRQ_TYPE_LEVEL_HIGH, DEVICE_NAME, NULL);
if(ret<0){
printk("Register IOPWM failed!/n");
return ret;
}
return ret;
}
static void __exit iopwm_exit(void)
{
free_irq(iopwm_irq,NULL);
misc_deregister(&misc);
}
module_init(iopwm_init);
module_exit(iopwm_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("
gfpeak@gmail.com");
