pio-drv.c

ARM9200+嵌入式linux下串口通信程序

/*
	pio driver for LPT2NET project
	author: zou jian guo <[e-mail]>
	date: 2004-10-18
	update: 2005-01-6

	
	pio_read:
        	read count bytes data to user,but if no enough data to read ,
		       then return the actual count bytes to user, the EF sigh 
			   is the driver to bethought, the user needn't take account.
	pio_write:
			user write the count bytes to pio ,the FF sigh need to be 
			careful deal with; 
	
	pio_ioctl: number 1 is to reset pio
*/



#ifndef __KERNEL__
#  define __KERNEL__
#endif
#ifndef MODULE
#  define MODULE
#endif


#include <linux/config.h>
#include <linux/module.h>
#include <linux/devfs_fs_kernel.h>

#include <linux/init.h>
#include <linux/kernel.h>   /* printk() */
#include <linux/slab.h>   /* kmalloc() */
#include <linux/fs.h>       /* everything... */
#include <linux/errno.h>    /* error codes */
#include <linux/types.h>    /* size_t */
#include <linux/proc_fs.h>
#include <linux/mm.h>
#include <linux/fcntl.h>    /* O_ACCMODE */
#include <linux/poll.h>    /* COPY_TO_USER */
#include <linux/ioport.h>
#include <linux/sched.h>
#include <linux/delay.h>  /* udelay */
#include <linux/interrupt.h>
#include <linux/tqueue.h>

#include <asm/io.h>
#include <asm/system.h>     /* cli(), *_flags */
#include <asm/arch/AT91RM9200.h>     /* cli(), *_flags */
#include <asm/arch/hardware.h> 


#define DEVICE_NAME		"pio"
#define pio_MAJOR 254
#define pio_MINOR 5

#define RS485_TX_ENABLE 	(1<<21)  //PA21 RTS0


static AT91PS_SYS  AT91_SYS=((AT91PS_SYS)AT91C_VA_BASE_SYS);
//extern AT91PS_SYS AT91_SYS;

static void AT91_PIO_INIT(void)
{
//pio clock enable	
	AT91_SYS->PMC_PCER = (1<<AT91C_ID_PIOA);
	
//PIO ENABLE
	AT91_SYS->PIOA_PDR = AT91C_PA17_TXD0 | AT91C_PA18_RXD0;
	AT91_SYS->PIOA_PER = AT91C_PA21_RTS0; //USED TO CTROL DE /RE OF THE MAX3485

//SET IO OUTPUT ENABLE
	AT91_SYS->PIOA_OER = AT91C_PA21_RTS0;
	AT91_SYS->PIOA_ODR = ~( AT91C_PA21_RTS0);

	AT91_SYS->PIOA_OWER = AT91C_PA21_RTS0;
	AT91_SYS->PIOA_OWDR = ~(AT91C_PA21_RTS0);

//pio interrupt disable
//	AT91_SYS->PIOA_IDR = AT91C_PA21_RTS0;

//Input Filter Enable Register
	AT91_SYS->PIOA_IFER = AT91C_PA21_RTS0;

//PULL UP ENABLE
	AT91_SYS->PIOA_PPUER= AT91C_PA21_RTS0;

}
/*********************************************************************/
static ssize_t  pio_write(struct file *filp,char *buffer, size_t count)
{ 
	return count;
}
/*********************************************************************/
static ssize_t  pio_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{
}
/*********************************************************************/
static int pio_ioctl(struct inode *inode, struct file *file, 
                 unsigned int cmd, unsigned long arg)
{
	switch(cmd){
		case 0:	AT91_SYS->PIOA_SODR = ~AT91C_PA21_RTS0;
				AT91_SYS->PIOA_CODR =  AT91C_PA21_RTS0;
			    printk("RS485 TX DISABLED\n");
				break;
		case 1: AT91_SYS->PIOA_SODR =  AT91C_PA21_RTS0;
				AT91_SYS->PIOA_CODR = ~AT91C_PA21_RTS0;
			    printk("RS485 TX ENABLED\n");
				break;
		default:
			printk("error cmd number\n");break;
	}
	return 0;
}
/*********************************************************************/
static int pio_open(struct inode *inode, struct file *file)
{
	MOD_INC_USE_COUNT;
	AT91_PIO_INIT();
	printk("device open sucess!\n");
	return 0;
}
/*********************************************************************/
static int  pio_release(struct inode *inode, struct file *filp)
{
	MOD_DEC_USE_COUNT;
	printk("device release\n");
	return 0;
}

/*********************************************************************/
static struct file_operations pio_fops = {
	owner:	THIS_MODULE,
	write:	pio_write,	
	read:	pio_read,	
	ioctl:	pio_ioctl,
	open:	pio_open,
	release:	pio_release,
};
/*********************************************************************/
#ifdef CONFIG_DEVFS_FS
static devfs_handle_t  devfs_pio_dir, devfs_pioraw;
#endif

/*********************************************************************/
static int __init pio_init(void)
{
	
#ifdef CONFIG_DEVFS_FS
	devfs_pio_dir = devfs_mk_dir(NULL, "pio", NULL);
	devfs_pioraw = devfs_register(devfs_pio_dir, "0", DEVFS_FL_DEFAULT,
			pio_MAJOR, pio_MINOR, S_IFCHR | S_IRUSR | S_IWUSR,
			&pio_fops, NULL);
#else
	int  result;
    SET_MODULE_OWNER(&pio_fops);
    result = register_chrdev(pio_MAJOR, "pio", &pio_fops);
    if (result < 0) return result;
//    if (pio_MAJOR == 0) pio_MAJOR = result; /* dynamic */
#endif
	printk(DEVICE_NAME " initialized\n");
	return 0;
}

/*********************************************************************/
static void __exit  pio_exit(void)
{
#ifdef CONFIG_DEVFS_FS
	devfs_unregister(devfs_pioraw);
	devfs_unregister(devfs_pio_dir);
#else
    unregister_chrdev(pio_MAJOR, "pio");
#endif
    //kfree(pio_devices);
	printk(DEVICE_NAME " unloaded\n");
}

/*********************************************************************/
module_init(pio_init);
module_exit(pio_exit);