IMX6输出可控PWM

驱动部分

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <linux/fs.h>  

/************硬件相关***************/
#include <mach/iomux-mx6q.h>

#define PWM_FREQENCY 1
#define DEV_NAME    "mypwm"
#define PWM_DEBUG 1   
/*pwm for this my_pwm*/
struct pwm_device *pwm = NULL;

static int my_pwm_open(struct inode *inode, struct file *filp)
{

   if(pwm != NULL)
	   return -EBUSY;

   /**
	* my_pwm正好挂载在I.MX6的pwm4上，所以这里申请3号（从零开始算）PWM
	*/
   pwm = pwm_request(3, "my_pwm");
   if ( pwm == NULL ) {
	   printk(KERN_ALERT"my_pwm open error.\n");
   }
	#ifdef PWM_DEBUG
	printk(KERN_ALERT"my_pwm opened\n");
	#endif
   return 0;
}

static int my_pwm_release(struct inode *inode, struct file *filp)
{
   pwm_disable(pwm);			   // 关闭pwm
   pwm_free(pwm);				   // 释放pwm
   pwm = NULL;
	#ifdef PWM_DEBUG
		printk(KERN_ALERT"my_pwm closed\n");
    #endif
   return 0;
}

static long my_pwm_ioctl(struct file *filp,
					   unsigned int cmd, unsigned long arg)
{
   if(pwm == NULL)
	   return -EINVAL;

   if(arg < 0)
	   return -EINVAL;

   switch (cmd) {
   case PWM_FREQENCY:
	   if(arg==0)
	   	{
		   pwm_disable(pwm);
		   #ifdef PWM_DEBUG
		   	printk(KERN_ALERT"my_pwm off\n");
		   #endif
	   	}
	   else
	   {
		   pwm_config(pwm, 1000000000/arg/2, 1000000000/arg);
		   pwm_enable(pwm);
		   #ifdef PWM_DEBUG
		   	printk(KERN_ALERT"my_pwm on\n");
		   #endif
	   }
	   break;
   default:
	   break;
   }

   return 0;
}

static struct file_operations my_pwm_fops = {
   .owner			   = THIS_MODULE,
   .unlocked_ioctl	   = my_pwm_ioctl,
   .open			   = my_pwm_open,
   .release 		   = my_pwm_release,
};

static struct miscdevice my_pwm_miscdev =
{
	.minor	= MISC_DYNAMIC_MINOR,
	.name	= DEV_NAME,
	.fops	= &my_pwm_fops,
};

static int __init my_pwm_init(void)
{
  	 //printk(KERN_ALERT"check my_pwm init.\n");
   	misc_register(&my_pwm_miscdev);//misc杂项设备是主设备号为10的驱动设备,自动创建节点
	mxc_iomux_v3_setup_pad(MX6Q_PAD_SD1_CMD__PWM4_PWMO);
	#ifdef PWM_DEBUG
		printk(KERN_ALERT"my_pwm init\n");
	#endif
   	return 0;
}

static void __exit my_pwm_exit(void)
{
  misc_deregister(&my_pwm_miscdev);
  #ifdef PWM_DEBUG
		printk(KERN_ALERT"my_pwm removed\n");
  #endif
}

module_init(my_pwm_init);
module_exit(my_pwm_exit);

MODULE_DESCRIPTION("pwm_my_pwm driver");
MODULE_LICENSE("GPL");

　　测试程序

#include<stdio.h>
#include<stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>

#define PWM_SET_FREQ 1
#define PWM_STOP     0


int fd;
int main(int argc, char **argv)//dev state freq
{
	char* filename;
	long int freq;

	filename=argv[1];
	if (argc != 4)
	    {
		  printf("parm limited!\n");
		  return 0;
		}
	printf("open %s \n",filename);
	fd=open(filename,O_RDWR);
	if(fd<0)
	{
		printf("can't open\n");
		return 0;
	}
	if(!strcmp("on",argv[2]))
	{
		printf("PWM ON!\n");
		freq=atol(argv[3]);
		ioctl(fd,PWM_SET_FREQ,freq);
		printf("PWM FREQ set:%d Hz \n",freq);
	}
	else if(!strcmp("off",argv[2]))
	{
		ioctl(fd,PWM_STOP);
		printf("PWM stop!\n");
	}
	else
		printf("error:param wrong!\n");
		while(1)
		{
			sleep(1000);
		}
	close(fd);
	return 0;
}