lcd_driver.c

来自「linux 12232液晶显示驱动,可根据具体电路的IO口做适当修改.」· C语言 代码 · 共 285 行

/*****************************************************************************/

/*
 *	lcd_driver.c -- driver for a C12232-8 LCD displays
 *
 *	(C) Copyright 2000-2008, guo ([e-mail])
 *	(C) Copyright 2000-2008, g Inc. (www.g.com) 
 */

/*****************************************************************************/

#include <linux/config.h>
#include <linux/version.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <asm/param.h>
#include <asm/uaccess.h>

#include "44b.h"

/*****************************************************************************/

/*
 *	Hardware specifics for LCD on the board.
 *	This is a 15 character by 2 line device.
 */

/* LCD display specifics */
#define	G_LCD_LINENUM	2
#define	G_LCD_LINELENGTH	15


#define LCD_DRIVER	"g LCD Driver v 0.1"

/*
 *	Define driver major number.
 */
#define	G_LCD_MAJOR	120

/*****************************************************************************/
/*
 *	Define normal text LCD control commands.
 */
#define	G_LCD_CLEAR		0x01		/* Clear all of LCD display */
#define	G_LCD_RETURN	0x02		/* Cursor to start of line */

#define	G_LCD_MODE		0x04		/* Mode command */
#define	G_LCD_MODE_INCR	0x02		/* Increment cursor on data */
#define	G_LCD_MODE_DECR	0x00		/* Decrement cursor on data */
#define	G_LCD_MODE_SHIFT	0x01		/* Display shift when full */
#define	G_LCD_MODE_NOSHIFT	0x00		/* No display shift */

#define	G_LCD_DISP		0x08		/* Display command */
#define	G_LCD_DISP_ON	0x04		/* Turn display on */
#define	G_LCD_DISP_OFF	0x00		/* Turn display off */
#define	G_LCD_DISP_CUR_ON	0x02		/* Turn cursor on */
#define	G_LCD_DISP_CUR_OFF	0x00		/* Turn cursor off */
#define	G_LCD_DISP_BLNK_ON	0x01		/* Blinking cursor on */
#define	G_LCD_DISP_BLNK_OFF	0x00		/* Blinking cursor off */

#define	G_LCD_SHIFT		0x10		/* SHift command */
#define	G_LCD_SHIFT_CUR	0x00		/* Cursor shift */
#define	G_LCD_SHIFT_DISP	0x08		/* Display shift */
#define	G_LCD_SHIFT_RIGHT	0x04		/* Right shift */
#define	G_LCD_SHIFT_LEFT	0x00		/* Left shift */

#define	G_LCD_FUNC		0x20		/* Function command */
#define	G_LCD_FUNC_4BIT	0x00		/* 4 bit data bus */
#define	G_LCD_FUNC_8BIT	0x10		/* 8 bit data bus */
#define	G_LCD_FUNC_1LINE	0x00		/* 1 line display */
#define	G_LCD_FUNC_2LINE	0x08		/* 2 line display */
#define	G_LCD_FUNC_FONT	0x00		/* Standard font */


/*****************************************************************************/

static void g_lcd_writechar(unsigned char c, unsigned char rwrs)
{
	unsigned char i;	
	rPDATC |= 0x04;//PC2 high, chip selected 

	/*synchronize*/
	for(i=0; i<5; i++){
		rPDATC |= (0x2);//PC1 high, SID sync bit 1
		rPDATC &= ~(0x1);//PC0 low, 
		udelay(1);
		rPDATC |= (0x1);//PC0 high, 
		udelay(1);		
	}
	
	//rPDATC &= ~(0x1<<1)//PC1  SID RW bit
	rPDATC =(rPDATC&(~(0x1<<1)))|(((rwrs>>1)&(0x1))<<1);//PC1 one bit
	rPDATC &= ~(0x1);//PC0 low, 
	udelay(1);
	rPDATC |= (0x1);//PC0 high, 
	udelay(1);
	
	//rPDATC &= ~(0x1<<1)//PC1  SID RS bit
	rPDATC =(rPDATC&(~(0x1<<1)))|(((rwrs)&(0x1))<<1);//PC1 one bit
	rPDATC &= ~(0x1);//PC0 low, 
	udelay(1);
	rPDATC |= (0x1);//PC0 high, 
	udelay(1);

	rPDATC &= ~(0x1<<1);//PC1 low, SID 0
	rPDATC &= ~(0x1);//PC0 low, 
	udelay(1);
	rPDATC |= (0x1);//PC0 high, 
	udelay(1);
		
	//four higher bits 	
	for(i=7; i>3; i--){
		rPDATC =(rPDATC&(~(0x1<<1)))|(((c>>i)&(0x1))<<1);//PC1 one bit
		rPDATC &= ~(0x1);//PC0 low, 
		udelay(1);
		rPDATC |= (0x1);//PC0 high, 
		udelay(1);	
	}
	for(i=0; i<4; i++){
		rPDATC &= ~(0x1<<1);//PC1 low, SID RW=0
		rPDATC &= ~(0x1);//PC0 low, 
		udelay(1);
		rPDATC |= (0x1);//PC0 high, 
		udelay(1);		
	}
	
	//four lower bits
	for(i=3; i>=0; i--){
		rPDATC =(rPDATC&(~(0x1<<1)))|(((c>>i)&(0x1))<<1);//PC1 one bit
		rPDATC &= ~(0x1);//PC0 low, 
		udelay(1);
		rPDATC |= (0x1);//PC0 high, 
		udelay(1);	
	}
	for(i=0; i<4; i++){
		rPDATC &= ~(0x1<<1);//PC1 low, SID RW=0
		rPDATC &= ~(0x1);//PC0 low, 
		udelay(1);
		rPDATC |= (0x1);//PC0 high, 
		udelay(1);		
	}	
	udelay(72000);
}

/*
 *	LCD initial hardware setup.
 */
static void g_lcd_hwsetup()
{

	/*
	 *	Initialize the LCD controller.
	 *	Some data sheets recommend doing the init write twice...
	 */
	g_lcd_writechar(G_LCD_FUNC | G_LCD_FUNC_8BIT ,0x00);
	g_lcd_writechar(G_LCD_FUNC | G_LCD_FUNC_8BIT ,0x00);
	g_lcd_writechar(G_LCD_DISP | G_LCD_DISP_ON,0x00);
	g_lcd_writechar(G_LCD_MODE | G_LCD_MODE_INCR,0x00);

	g_lcd_writechar(G_LCD_CLEAR,0x00);
	
}

/*****************************************************************************/

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

/*****************************************************************************/

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

/*****************************************************************************/

static void g_lcd_resetposn(void)
{
	g_lcd_writechar(0x80,0x00);
}

/*****************************************************************************/

static void g_lcd_clear(void)
{
	g_lcd_writechar(G_LCD_CLEAR,0x00);
}

/*****************************************************************************/

static ssize_t g_lcd_write(struct file *filp, const char *buf, size_t count, loff_t *ppos)
{
	char	*p, c;
	int	num;

	p = (char *) buf;
	
	if(*p == 0){
		g_lcd_clear();	
		return 0;
	}
	
	for (num = 0; num < count; num++) {
		get_user(c, p++);
		if(c == 0x00) break;
		g_lcd_writechar(c, 0x01);	
	}

	return(num);
}

/*****************************************************************************/

static int g_lcd_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
	int	rc = 0;

	switch (cmd) {

	case 1: /* Directly address X/Y cursor position */
		/*
		 * This ioctl is essentailly a duplication of the
		 * 0x1f escape code code in the write routine.
		 * This version allows a wider range of values to be set
		 */
		g_lcd_resetposn();
		break;
		
	default:
		rc = -EINVAL;
		break;
	}

	return(rc);
}

/*****************************************************************************/

/*
 *	Exported file operations structure for driver...
 */

struct file_operations	g_lcd_fops = {
	write:		g_lcd_write,	/* write */
	ioctl:		g_lcd_ioctl,	/* ioctl */
	open:		g_lcd_open,		/* open */
	release:	g_lcd_release,	/* release */
};


/*****************************************************************************/

static int __init g_lcd_init(void)
{
	int	rc;

	/* Register g_lcd as character device */
	if ((rc = register_chrdev(G_LCD_MAJOR, "lcd", &g_lcd_fops)) < 0) {
		printk(KERN_WARNING "G_LCD: can't get major %d\n",
			G_LCD_MAJOR);
		return (-EBUSY);
	}

	printk("G_LCD: Copyright (C) 2000-2008, Guo "
		"([e-mail])\n");

	/* Hardware specific initialization */
	g_lcd_hwsetup();

	return 0;
}

module_init(g_lcd_init);

/*****************************************************************************/