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;
}