DM8168 PWM驱动与測试程序

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，如今就要进入主题了。

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
");
	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
");
	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 

測试程序 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 !
");
		exit(1);
	}
	else
	{
		printf("open success ! duty_cycle : %s
",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;
}

測试 ：

模块编译后载入：insmod dm8168_pwm.ko

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

执行：./pwm_test 50

输出为50%的PWM波形，測试成功。