DM8168 PWM驱动与测试程序

昨天把DM8168的Timer设置给摸了一遍，为写PWM的底层驱动做好了准备，现在就要进入主题了。

dm8168_pwm.c:

 

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/uaccess.h> /* copy_to_user,copy_from_user */
#include <linux/miscdevice.h>
#include <linux/device.h>
#include <asm/io.h>

static struct class  *pwm_class;

volatile unsigned long *CLK_CTL;
volatile unsigned long *TCLR;
volatile unsigned long *TCRR;
volatile unsigned long *TLDR;
volatile unsigned long *TMAR;

int pwm_open (struct inode *inode,struct file *filp)

{
    *CLK_CTL = 0x00000002;
    *TCLR    = 0;
    *TLDR    = 0xffffffe0;
    *TMAR    = 0xfffffff0;
    *TCRR    = 0xffffffe0;
    return 0;
}

ssize_t pwm_read (struct file *filp, char __user *buf, size_t count,loff_t *f_pos)
{
    return 0;
}

ssize_t pwm_write (struct file *filp, const char __user *buf, size_t count,loff_t *f_pos)
{
    char duty_buf[2];
    int ret;
    ret = copy_from_user(duty_buf,buf,count);
    *TMAR    = 0xffffffe0 + (unsigned char)(duty_buf[0]*30/100);  //分辨率略低，仅为demo
    *TCLR    = 0x1843;
    return count;
}

struct file_operations pwm_fops =
{
    .owner   = THIS_MODULE,
    .open    = pwm_open,
    .read    = pwm_read,
    .write   = pwm_write,
} ;

int major;
int pwm_init (void)
{

    major = register_chrdev(0,"DM8168_PWM",&pwm_fops);
    pwm_class = class_create(THIS_MODULE, "DM8168_PWM");
    device_create(pwm_class,NULL,MKDEV(major,0),NULL,"pwm");

    CLK_CTL = (volatile unsigned long *)ioremap(0x4818157C,4);
    TCLR    = (volatile unsigned long *)ioremap(0x48044038,4);
    TCRR    = (volatile unsigned long *)ioremap(0x4804403C,4);
    TLDR    = (volatile unsigned long *)ioremap(0x48044040,4);
    TMAR    = (volatile unsigned long *)ioremap(0x4804404C,4);
    printk ("pwm is ready\n");
    return 0;
}

void pwm_exit (void)
{
    unregister_chrdev(major,"DM8168_PWM");
    device_destroy(pwm_class,MKDEV(major,0));
    class_destroy(pwm_class);

    iounmap(CLK_CTL);
    iounmap(TCLR);
    iounmap(TCRR);
    iounmap(TLDR);
    iounmap(TMAR);
    printk ("module exit\n");
    return ;
}

MODULE_LICENSE("GPL");
module_init(pwm_init);
module_exit(pwm_exit);

Makefile:

 

 

obj-m:= dm8168_pwm.o

CROSSCOMPILE := /opt/codesourcery/arm-2009q1/bin/arm-none-linux-gnueabi-

CC  := $(CROSSCOMPILE)gcc

KDIR:=/home/***/ti-ezsdk_dm816x-evm_5_03_01_15/board-support/linux-2.6.37-psp04.00.01.13.patch2

PWD :=$(shell pwd)

default:
    $(MAKE) -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi-
clean:
    rm -rf *.ko *.o .*cmd *.mod.c .tmp_versions

 

 

测试程序 pwm_test.c:

 

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>

int pow_10(char m)
{
    int j;
    int res=1;
    for(j=0;j<m;j++)
    {
        res = res * 10;
    }
    return res;
}

int main(int argc, char *argv[])
{
    int  fd;
    char *buf;
    char i;
    int  val=0;

    fd=open("/dev/pwm",O_RDWR);
    if(fd<0)
    {
        printf("open device failed !\n");
        exit(1);
    }
    else
    {
        printf("open success ! duty_cycle : %s\n",argv[1]);
        buf=argv[1];
        buf+=strlen(argv[1])-1;
    }

    for(i=0;i<strlen(argv[1]);i++)
    {
        val += pow_10(i)*(*buf-0x30);
        buf --;
    }
    write(fd,&val,1);
    close(fd);
    return 0;
}

测试 ：

 

模块编译后加载：insmod dm8168_pwm.ko

交叉编译测试程序：arm-none-linux-gnueabi-gcc -o pwm_test pwm_test.c

运行：./pwm_test 50

输出为50%的PWM波形，测试成功。