de2_seg7.c

Altera DE2开发板的LED、LCD、SEG7和按键的linux下的设备驱动程序

/*  
	Copyright (C) 2007 Philipp Lutz

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or 
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
///////////////////////////////////////////////////////////////////////////////////////////////////
/*
Description:
------------
This device driver is capable of controlling the 7-segment display found on the DE2 board.
It uses the major number SEG7_MAJOR to be able to create a corresponding device file to access the device.
In uClinux for NIOS2 the automatic creation of device files is found in the script located at
"vendors/Altera/nios2nommu/romfs_list".

In uClinux it works with the following command:
mknod /dev/leds_red 666 c 240 0

The device driver reads hex values!

*/
///////////////////////////////////////////////////////////////////////////////////////////////////
/* 
Debug defines:
--------------
uncomment following line to use the kernelmodule without
io (inb / outb) functions, needed for debug purposses on host machine. */
//#define TEST

// enables debug-kernel-messages (viewed via "dmesg" command)
//#define DEBUG
///////////////////////////////////////////////////////////////////////////////////////////////////

#include "de2_includes.h"

// major numbers for identifying the device files
#define SEG7_MAJOR		243

// base-adress mapping to device names according to linux-2.6.x/include/nios2_system.h
#define SEG7_BASE		na_SEG7


/* define buffers for the strings sended to user */
char seg7_string[STRING_LEN] = "\0";
char* seg7_ptr = seg7_string;

/* device files open? */
int seg7_is_open = 0;


void seg7_write_value(unsigned long int value)
{
	np_pio *pio_seg7 =(np_pio *)(SEG7_BASE);
#ifndef TEST
	outl(value,&pio_seg7->np_piodata);
#endif
}


/////////////////////////////////////////////////////////////////////////
// Open handler
/////////////////////////////////////////////////////////////////////////
static int seg7_open(struct inode *inode, struct file *file)
{
#ifdef DEBUG
	printk("seg7_open called\n");
#endif
	if (seg7_is_open++) {
		printk("device busy...\n");
		return -EBUSY;
	}
	try_module_get(THIS_MODULE);
	return 0;
}


/////////////////////////////////////////////////////////////////////////
// Release/Close handler
/////////////////////////////////////////////////////////////////////////
static int seg7_release(struct inode *inode, struct file *file)
{
#ifdef DEBUG
	printk("seg7_release called\n");
#endif
	
	--seg7_is_open;			
	module_put(THIS_MODULE);
	return 0;
}


/////////////////////////////////////////////////////////////////////////
// Write handler
/////////////////////////////////////////////////////////////////////////
static ssize_t seg7_write(struct file *filp, const char *buff, size_t len, loff_t * off)
{
#ifdef DEBUG
	printk("seg7_write called\n");
	printk("buffer to copy: %s\n", buff);
#endif
	
	int not_copied = 0;

	if(len > (STRING_LEN-1))
		len = STRING_LEN-1;

	/* copy data from user into buffer seg7_string */
	not_copied = copy_from_user(seg7_string,buff,len);
	seg7_string[len] = '\0';

#ifdef DEBUG
	printk("write to SEG7: %s\ncopied: %i\nnot_copied: %i\n", seg7_string, len-not_copied,not_copied);
#endif
	seg7_write_value((unsigned long int)atolx(seg7_string));
	return len-not_copied;
}


// Structure which assigns handler functions to hardware operations
static struct file_operations fops_seg7 = 
{
	.write		= seg7_write,
	.open		= seg7_open,
	.release	= seg7_release,
};


/////////////////////////////////////////////////////////////////////////
// Init funktion
/////////////////////////////////////////////////////////////////////////
static int __init mod_init(void)
{
	np_pio *pio_seg7 = (np_pio *)(SEG7_BASE);

	// reserving memory regions for the PIO port
	if(!request_mem_region((unsigned long)SEG7_BASE, sizeof(np_pio), "de2_seg7"))
		return -1;
	
	// registering PIO port as character device to the kernel
	if(register_chrdev(SEG7_MAJOR, "de2_seg7", &fops_seg7))
	{
		printk("register_chrdev of de2_seg7 failed!\n");
		release_mem_region((unsigned long)SEG7_BASE, sizeof(np_pio));
		return -EIO;
	}
	
#ifdef DEBUG
	printk("de2_seg7 registered successfully!\n");
#ifdef	TEST
	print("TEST mode active, so no I/O interaction is possible!\n");
#endif
#endif
	
	// set PIO port as output
#ifndef TEST
	outl(-1, &pio_seg7->np_piodirection);
#endif
	return 0;

}


/////////////////////////////////////////////////////////////////////////
// Exit function (will be spared if build-in device driver selected)
/////////////////////////////////////////////////////////////////////////
static void __exit mod_exit(void)
{
	// unregistering character device
	unregister_chrdev(SEG7_MAJOR,"de2_seg7");

	// releasing memory region
	release_mem_region((unsigned long)SEG7_BASE, sizeof(np_pio));
}

// declaring the init/exit functions of the module
module_init( mod_init );
module_exit( mod_exit );
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Philipp Lutz");