IMX6输出可控PWM

/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");
}