d.c

linux 基于 s3c2440 的rs485驱动及测试程序,可正常收发16Mhz字节数据!

#include <linux/fs.h>
#include <linux/iobuf.h>
//#include <linux/major.h>   
#include <linux/blkdev.h>
#include <linux/capability.h>
#include <linux/smp_lock.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <linux/module.h>

//#define RS485DE  	 GPIO_C5
#define RS485DE  	 GPIO_C5
#define nREV      1
#define nSENT     0
#define RS485SENTBEGIN  1
#define RS485SENTOVER   2

static int RS485_MAJOR=0;
static devfs_handle_t devfs_handle;

int    rs485_open(struct inode*, struct file *);
int    rs485_colse(struct inode*, struct file *);
int    rs485_ioctl(struct inode*inode,struct file *flip,unsigned int cmd,unsigned long arg);


static struct file_operations gpio_ctl_fops= { 
	ioctl:       rs485_ioctl,
	open:        rs485_open,
	release:     rs485_colse,
};

int __init gpio_init(void) 
{ 
	int result; 
	result = register_chrdev(0, "rs485driver", &gpio_ctl_fops); 
	if (result < 0) { 
		printk("rs485de register error!\n"); 
		return result; 

	} 
	RS485_MAJOR=result;
	devfs_handle = devfs_register(NULL, "rs485driver", DEVFS_FL_DEFAULT,RS485_MAJOR, 0, S_IFCHR | S_IRUSR | S_IWUSR,&gpio_ctl_fops, NULL);
	return 0; 
} 


int gpio_release(struct inode*inode, struct file *filp)
{ 
  devfs_unregister(devfs_handle);
	unregister_chrdev(RS485_MAJOR, "rs485driver"); 
}

int    rs485_open(struct inode*inode, struct file *filp)
{
	 
  set_gpio_ctrl(GPIO_MODE_OUT | RS485DE); 
  set_gpio_pullup(RS485DE);
  write_gpio_bit(GPIO_MODE_OUT | RS485DE,nREV);
	return 0;
}


int    rs485_colse(struct inode*inode, struct file *filp)
{ 
	return 0;
}

void set_rs485de_sent(void)
{
	udelay(3000);
	write_gpio_bit(GPIO_MODE_OUT | RS485DE,nSENT);
	//udelay(100);
	//
}

void set_rs485de_receive(void)
{
	udelay(8000);
	write_gpio_bit(GPIO_MODE_OUT | RS485DE,nREV);
	//udelay(1000);
	
}


int rs485_ioctl(struct inode*inode,struct file *flip,unsigned int cmd,unsigned long arg)
{

	int ret=0;
  switch(cmd)
  {
  	case RS485SENTBEGIN:
  	      set_rs485de_sent();
  	      break;
  	case RS485SENTOVER:
  	      set_rs485de_receive();
  	      break;
  	default:
  	      ret=-1;
  	      break;
  }      
	return ret;
}

module_init(gpio_init); //用户加载该驱动时执行insmod gpio_driv.o就会自动调用gpio_init函数，它是驱动
//的入口点，相当于应用程序的main函数。
module_exit(gpio_release); //用户卸载该驱动rmmod gpio_driv时执行