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.oCROSSCOMPILE := /opt/codesourcery/arm-2009q1/bin/arm-none-linux-gnueabi-CC  := $(CROSSCOMPILE)gcc KDIR:=/home/***/ti-ezsdk_dm816x-evm_5_03_01_15/board-support/linux-2.6.37-psp04.00.01.13.patch2PWD :=$(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。