基于s3c2440的12864液晶驱动

12864是128*64点阵液晶模块的点阵数简称，业界约定俗成的简称。

一、液晶显示模块概述
12864A-1 汉字图形点阵液晶显示模块,可显示汉字及图形,内置 8192 个中文汉字(16X16 点阵,16*8=128,16*4=64,一行只能写 8 个汉字,4 行;、128 个字符(8X16 点阵)及 64X256 点阵显示 RAM(GDRAM))。
主要技术参数和显示特性:
电源:VDD 3.3V~+5V(内置升压电路,无需负压);
显示内容:128 列× 64 行(128 表示点数)
显示颜色:黄绿
显示角度:6:00 钟直视
LCD 类型:STN
与 MCU 接口:8 位或 4 位并行/3 位串行
配置 LED 背光
多种软件功能:光标显示、画面移位、自定义字符、睡眠模式等

引脚定义：D0-D7，RS，RES，RD，WR，CS，BL；具体头文件定义如下：

#ifndef    LCD12864_H
#define LCD12864_H

#define LCD12864_MAJOR    242
#define DEV_NAME        "lcd12864"

#define LCD12864_IOCTL 'l'
#define SET_FONT_SIZE    _IOW(LCD12864_IOCTL,0 ,unsigned int)
#define SET_LCD_PAGE    _IOW(LCD12864_IOCTL,1 ,unsigned int)
#define SET_LCD_COLUMN    _IOW(LCD12864_IOCTL,2 ,unsigned int)
#define CLR_SCREEN        _IOW(LCD12864_IOCTL,3 ,unsigned int)
#define BACKLIGHT_CTRL  _IOW(LCD12864_IOCTL,4 ,unsigned int)
#define CONTRAST_SETTING _IOW(LCD12864_IOCTL,5 ,unsigned int)

#define LCD_DATA_0    S3C2410_GPC8
#define LCD_DATA_1    S3C2410_GPC9
#define LCD_DATA_2    S3C2410_GPC10
#define LCD_DATA_3    S3C2410_GPC11

#define LCD_DATA_4    S3C2410_GPC12
#define LCD_DATA_5    S3C2410_GPC13
#define LCD_DATA_6    S3C2410_GPC14
#define LCD_DATA_7    S3C2410_GPC15


#define LCD_E_RD    S3C2410_GPD0
#define LCD_RW_WR    S3C2410_GPD1
#define LCD_RS        S3C2410_GPD2
#define LCD_RES        S3C2410_GPD3
#define LCD_CS1        S3C2410_GPD4
#define LCD_BL        S3C2410_GPD5


#define LCD_DATA_CFG0_OUTP    S3C2410_GPC8_OUTP
#define LCD_DATA_CFG1_OUTP    S3C2410_GPC9_OUTP
#define LCD_DATA_CFG2_OUTP    S3C2410_GPC10_OUTP
#define LCD_DATA_CFG3_OUTP    S3C2410_GPC11_OUTP

#define LCD_DATA_CFG4_OUTP    S3C2410_GPC12_OUTP
#define LCD_DATA_CFG5_OUTP    S3C2410_GPC13_OUTP
#define LCD_DATA_CFG6_OUTP    S3C2410_GPC14_OUTP
#define LCD_DATA_CFG7_OUTP    S3C2410_GPC15_OUTP


#define LCD_E_RD_CFG_OUTP    S3C2410_GPD0_OUTP
#define LCD_RW_WR_CFG_OUTP    S3C2410_GPD1_OUTP
#define LCD_RS_CFG_OUTP        S3C2410_GPD2_OUTP
#define LCD_RES_CFG_OUTP    S3C2410_GPD3_OUTP
#define LCD_CS1_CFG_OUTP    S3C2410_GPD4_OUTP
#define LCD_BL_CFG_OUTP        S3C2410_GPD5_OUTP


#define FONT_SIZE_8        8
#define FONT_SIZE_16    16


#endif

将引脚单独用头文件重新自己定义一次，以提高代码的可移植性。

下面看看模块初始化/释放函数：

static int __init lcd12864_init(void)
{
    int ret;
    dev_t devno;

    DBPRINTF(KERN_ALERT "%s enter!\n",__func__);
    devno = MKDEV(lcd12864_major,0);
    if((ret = register_chrdev_region(devno,1,DEV_NAME))<0)
    {
        if((ret = alloc_chrdev_region(&devno, 0, 1, DEV_NAME))<0)
        {
            DBPRINTF(KERN_ALERT "chrdev region fail!ret=%d;\n",ret);
            return ret;
        }
        else
        {
            lcd12864_major = MAJOR(devno);
        }        
    }
    cdev_init(&lcd_cdev, &lcd12864_ops);
    lcd_cdev.owner=THIS_MODULE;
    lcd_cdev.ops = &lcd12864_ops;
    
    ret = cdev_add(&lcd_cdev, devno, 1);
    if(ret<0)
    {
        goto fail_reg;
    }

    lcd_dev_class = class_create(THIS_MODULE, DEV_NAME);
    if(IS_ERR(lcd_dev_class))
    {
        goto fail_cdev;
    }
    device_create(lcd_dev_class, NULL, devno, NULL, DEV_NAME);

    lcd_bd_info = kmalloc(sizeof(struct lcd_board_info),GFP_KERNEL);
    lcd_bd_info->font_size = 16;

#ifdef NORMAL
    lcd_bd_info->pag = 0;
    lcd_bd_info->column = 0;
#else
    lcd_bd_info->pag = 6;
    lcd_bd_info->column = 112;
#endif
    lcd_bd_info->lcd_data_t = lcd_data_table;
    lcd_bd_info->lcd_data_cfg_t = lcd_data_cfg_table;

    spin_lock_init(&lock);

    gpio_pin_init();    
    //gpio_pin_init();


    ret = init_lcd12864();
    if(ret<0)
    {
        goto fail_dev;
    }
    back_light_ctrl(1);
    clear_lcd_screen(0x00);    
    DBPRINTF(KERN_ALERT "%s leave,init success!\n",__func__);
    return ret;
    
fail_dev:
    device_destroy(lcd_dev_class, devno);
    class_destroy(lcd_dev_class);

fail_cdev:
    cdev_del(&lcd_cdev);
fail_reg:
    unregister_chrdev_region(devno, 1);
    return ret;
}


static void __exit lcd12864_exit(void)
{
    kfree(lcd_bd_info);
    device_destroy(lcd_dev_class, MKDEV(lcd12864_major, 0));
    class_destroy(lcd_dev_class);
    cdev_del(&lcd_cdev);
    unregister_chrdev_region(MKDEV(lcd12864_major, 0), 1);
}

module_init(lcd12864_init);
module_exit(lcd12864_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("HOY");
MODULE_DESCRIPTION("gonsin 128x64 lcd driver");

以上主要工作是：通过register_chrdev_region静态分配设备号devno,如果分配失败，则通过系统alloc_chrdev_region动态分配；

此处通过cdev创建字符设备;通过cdev_add添加入系统中。通过class_create和device_create生成并注册一个逻辑设备，通过此工作，可以在/dev/下面看到设备名；

初始化lcd_board_info结构，lcd_board_info结构定义如下：

struct lcd_board_info{

    unsigned int font_size;
    unsigned int pag;
    unsigned int column;
    unsigned long* lcd_data_t;
    unsigned long* lcd_data_cfg_t;
};

static struct lcd_board_info* lcd_bd_info;

其他变量和头文件定义如下：

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/init.h>
#include <mach/regs-gpio.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/device.h>
#include <asm/io.h>
#include  <linux/delay.h>

#define DEBUG        //调试状态
#ifdef DEBUG
#define DBPRINTF(fmt,args...)     printk(KERN_ALERT "lcd:" fmt, ##args)
#else
#define DBPRINTF(fmt,args...)
#endif

#include "lcd_12864.h"

#define NORMAL  //正常模式


static struct class* lcd_dev_class;

struct cdev lcd_cdev;

static int lcd12864_major = LCD12864_MAJOR;

static unsigned long lcd_data_table[]={
    LCD_DATA_0,
    LCD_DATA_1,
    LCD_DATA_2,
    LCD_DATA_3,

    LCD_DATA_4,
    LCD_DATA_5,
    LCD_DATA_6,
    LCD_DATA_7,
};

/**/
static unsigned long lcd_data_cfg_table[] =
{
    LCD_DATA_CFG0_OUTP,
    LCD_DATA_CFG1_OUTP,
    LCD_DATA_CFG2_OUTP,
    LCD_DATA_CFG3_OUTP,

    LCD_DATA_CFG4_OUTP,
    LCD_DATA_CFG5_OUTP,
    LCD_DATA_CFG6_OUTP,
    LCD_DATA_CFG7_OUTP,
};

/*
static unsigned char io_read_byte()
{

}
*/
spinlock_t lock;

然后调用以下函数进行gpio引脚的初始化、液晶屏的初始化：

static int gpio_pin_init(void)
{

    int ii;
    s3c2410_gpio_cfgpin(LCD_CS1, LCD_CS1_CFG_OUTP);
    s3c2410_gpio_cfgpin(LCD_RES, LCD_RES_CFG_OUTP);
    s3c2410_gpio_cfgpin(LCD_RS, LCD_RS_CFG_OUTP);
    s3c2410_gpio_cfgpin(LCD_RW_WR, LCD_RW_WR_CFG_OUTP);
    s3c2410_gpio_cfgpin(LCD_E_RD, LCD_E_RD_CFG_OUTP);
    s3c2410_gpio_cfgpin(LCD_BL, LCD_BL_CFG_OUTP);

    for(ii=0; ii<8; ii++)
    {
        s3c2410_gpio_cfgpin(lcd_bd_info->lcd_data_t[ii], lcd_bd_info->lcd_data_cfg_t[ii]);
    }
    return 0;
}


static unsigned char init_cmd[]={
    0xe2,
    0xa0,
    0xc0,
    0xA2,
    0x2B,
    0x2E,
    0x2F,
    0x27,
    0xAF,
    0,
};


static int init_lcd12864(void)
{

    int ii;
    s3c2410_gpio_setpin(LCD_CS1, 0);
    udelay(500);
    s3c2410_gpio_setpin(LCD_RES, 0);
    udelay(500);
    s3c2410_gpio_setpin(LCD_RES, 1);
    udelay(500);

    for(ii=0;init_cmd[ii]!=0;ii++)
    {
        send_cmd(init_cmd[ii]);
        udelay(50);
    }
    return 0;
}

以下为写液晶屏和写命令的操作：

#ifdef NORMAL
/*往液晶中写入1个字符数据*/
static void io_write_byte(unsigned char data)
{
    unsigned char ii;
    spin_lock(&lock);

    for(ii=0;ii<8;ii++)
    {
        if(data&0b1)
        {
            s3c2410_gpio_setpin(lcd_bd_info->lcd_data_t[ii], 1);
        }
        else
        {
            s3c2410_gpio_setpin(lcd_bd_info->lcd_data_t[ii], 0);
        }
        data = data>>1;
    }
    //__raw_writel(((__raw_readl(S3C2410_GPCDAT)&~(0xff<<8))|(data<<8)),S3C2410_GPCDAT);

    spin_unlock(&lock);

    s3c2410_gpio_setpin(LCD_RS, 1);
    s3c2410_gpio_setpin(LCD_RW_WR, 0);
    s3c2410_gpio_setpin(LCD_E_RD, 1);
    s3c2410_gpio_setpin(LCD_CS1, 1);
    udelay(1);
    s3c2410_gpio_setpin(LCD_CS1, 0);
    udelay(1);
    
}
#else
static void io_write_byte(unsigned char data)
{
    unsigned char ii;
    spin_lock(&lock);
    for(ii=0;ii<8;ii++)
    {
        if(data&0x80)
        {
            //DBPRINTF(KERN_ALERT "[||||||||||||||||||||]\n");
            s3c2410_gpio_setpin(lcd_bd_info->lcd_data_t[ii], 1);
        }
        else
        {
            //DBPRINTF(KERN_ALERT "[--------------------]\n");
            s3c2410_gpio_setpin(lcd_bd_info->lcd_data_t[ii], 0);
        }
        data = data<<1;
    }
    spin_unlock(&lock);
    //DBPRINTF(KERN_ALERT "\n");

    s3c2410_gpio_setpin(LCD_RS, 1);
    s3c2410_gpio_setpin(LCD_RW_WR, 0);
    s3c2410_gpio_setpin(LCD_E_RD, 1);

    s3c2410_gpio_setpin(LCD_CS1, 1);
    udelay(1);
    s3c2410_gpio_setpin(LCD_CS1, 0);
    udelay(1);
}
#endif

//发送命令
static int send_cmd(unsigned char cmd)
{
    int ii;
    unsigned char tmp;
    tmp = 0x00;
    spin_lock(&lock);

    for(ii=0;ii<8;ii++)
    {
        if(cmd&0x80)
        {
            s3c2410_gpio_setpin(lcd_bd_info->lcd_data_t[ii], 1);
        }
        else
        {
            s3c2410_gpio_setpin(lcd_bd_info->lcd_data_t[ii], 0);
        }
        cmd = cmd<<1;
    }
    /*******************/
/*
    for(ii=0;ii<8;ii++)
    {
        tmp = tmp<<1;
        if(cmd&0b1)
        {
            tmp|=0b1;
        }
        else
        {
            tmp &= 0b0;
        }
        cmd = cmd>>1;

    }    
    __raw_writel(((__raw_readl(S3C2410_GPCDAT)&~(0xff<<8))|(tmp<<8)),S3C2410_GPCDAT);*/
    /*******************/

    spin_unlock(&lock);


    s3c2410_gpio_setpin(LCD_RS, 0);
    s3c2410_gpio_setpin(LCD_RW_WR, 0);
    s3c2410_gpio_setpin(LCD_E_RD, 1);
    s3c2410_gpio_setpin(LCD_CS1, 1);
    udelay(1);

    s3c2410_gpio_setpin(LCD_CS1, 0);
    udelay(1);
    return 0;
}



static int dev_write_data(const char* data)
{
    unsigned char dl,dh;
    int i,j;
    spin_lock(&lock);
    dh = lcd_bd_info->column/16;
    dl = lcd_bd_info->column-dh*16;
    for(i=0; i<2; i++)
    {
        send_cmd(0xB7-i-lcd_bd_info->pag);
        send_cmd(0x10+dh);
        send_cmd(dl);

#ifdef NORMAL
        for(j=0;j<16;j++)
            io_write_byte(data[lcd_bd_info->font_size*i+j]);
#else
        for(j=0;j<16;j++)
            io_write_byte(data[lcd_bd_info->font_size*(1-i)+(15-j)]);
#endif
    }
    spin_unlock(&lock);
    return 0;
}

因为公司结构方面的需要，要将液晶倒转显示，所以此处做了两个不同的方案，如果定义了NORMAL,则正常显示，否则倒转显示;

其他对液晶屏控制的操作如下：

/*清除屏幕*/
static void clear_lcd_screen(unsigned char clr_data)
{
    unsigned char page_addr = 0xb7;
    unsigned int page_num;
    int ii;
    for(page_num=0; page_num<8; page_num++)
    {
        send_cmd(page_addr);
        send_cmd(0x10);
        send_cmd(0x00);
        for(ii=0; ii<128; ii++)
            io_write_byte(clr_data);
        page_addr--;
    }
}

static int lcd12864_open(struct inode* inode, struct file* filp)
{
    return 0;
}

static int lcd12864_release(struct inode* inode, struct file* filp)
{
    return 0;
}

static ssize_t lcd12864_write(struct file* filp, char __user* buf, size_t size, loff_t offset)
{
    char* kbuf;
//    int count;

    kbuf = kmalloc(size, GFP_KERNEL);    
    copy_from_user(kbuf, buf, size);
    dev_write_data(kbuf);

    kfree(kbuf);
    return 0;
}

static int contrast_setting(int val)
{
    if((val&0xff)>0x3e)
        return -1;
    send_cmd(0x81);
    send_cmd(val&0xff);
    DBPRINTF(KERN_ALERT "contrast setting,val is%d\n",val);
    return 0;
}
/*背光控制*/
static int back_light_ctrl(int bl)
{
    if(bl<0)
    {
        return -1;
    }
    else if(bl==0)
    {
        s3c2410_gpio_setpin(LCD_BL, 0);
        DBPRINTF(KERN_ALERT "back light set value is 0\n");
    }
    else
    {
        s3c2410_gpio_setpin(LCD_BL, 1);
        DBPRINTF(KERN_ALERT "back light set value is 1\n");
    }
    return 0;
}

static int lcd12864_ioctl(struct inode* inode,struct file* filp, unsigned int cmd, unsigned long args)
{
    int ret;
    spin_lock(&lock);
    ret = 0;
    DBPRINTF(KERN_ALERT "%s",__func__);
    switch(cmd)
    {
        case SET_FONT_SIZE:
        {
            int size = *(int*)args;
            if(size == FONT_SIZE_8||size == FONT_SIZE_16)
            {
                lcd_bd_info->font_size = size;
            }
            else
            {
                ret = -1;
                DBPRINTF(KERN_ALERT "set font size fail!\n");
                goto  ioctl_fail;
            }
            break;
        }
        case SET_LCD_PAGE:
        {
            int tmp = *(int*)args;
            if(tmp>63)
                return -1;


#ifdef NORMAL
            lcd_bd_info->pag = tmp;
#else
            lcd_bd_info->pag = 6-tmp;
#endif
            DBPRINTF(KERN_ALERT "set pag is %d\n",lcd_bd_info->pag);
            break;
        }
        case SET_LCD_COLUMN:
        {
            int tmp = *(int*)args;
            if(tmp>127)
                return -1;
#ifdef NORMAL
            lcd_bd_info->column =tmp;
#else
            lcd_bd_info->column =112-tmp;
#endif
            DBPRINTF(KERN_ALERT "set column is %d\n",lcd_bd_info->column);
            break;
        }
        case CLR_SCREEN:
        {
            unsigned char data = *(char*)args;
            clear_lcd_screen(data);
            break;
        }
        case BACKLIGHT_CTRL:
        {        
            int bl = *(int*)args;
            ret = back_light_ctrl(bl);
            break;
        }
        case CONTRAST_SETTING:
        {
            int con = *(int*)args;
            ret = contrast_setting(con);
            break;
        }

    }
    spin_unlock(&lock);
    return ret;    
ioctl_fail:
    spin_unlock(&lock);
    return ret;
}

最后看看file_operations结构体：

static struct file_operations lcd12864_ops={
    .owner = THIS_MODULE,
    .open = lcd12864_open,
    .release = lcd12864_release,
    .write = lcd12864_write,
    //.read = lcd12864_read,
    .ioctl = lcd12864_ioctl,
};

以上则是液晶屏的驱动程序，很简单吧？哈哈~~

Makefile如下所示：

obj-m:=lcd_12864.o
KDIR=/home/project/linux-res/linux-2.6.30.4/

all:
    $(MAKE) -C $(KDIR) M=$(PWD)

.PHONY:clean
clean:
    rm -f *.o *.ko *.mod.c *.mod.o *.tmp_versions

最后是液晶屏测试程序：

enum {
    FONT_SIZE8,
    FONT_SIZE16,
    FONT_SIZE32,
};


/*将字符数组里面的每一位取反*/
void oppersite(const char* cin, __out char* cout,int len)
{
    int i=0;

    for(i=0;i<len;i++)
    {
        cout[i]=~cin[i];
    }
}

/*由size_flag 解析出字体大小*/
int prase_size_flag(int size_flag)
{
    int fsize;
    switch(size_flag)
    {
        case FONT_SIZE8:
            fsize = 8;
            break;
        case FONT_SIZE16:
            fsize = 16;
            break;
        case FONT_SIZE32:
            fsize = 32;
            break;
        default:
            printf("size_flag is involid!\n");
            return -1;
    }
    return fsize;
}

int prase_row(int pag)
{
    return pag*2;
}

int prase_column(int col)
{
    return col*16;
}

/*显示一个选中的字符
ch:字符的16进制数组
pag:第几页;0-7
col:第几列;0-127
size_flag:字体枚举
*/
int show_select_ch(int fd, const char* ch, int pag, int col, int size_flag)
{
    char chtmp[50];
    int fsize;
    
    if(!ch)
        return -1;
    
    if((fsize=prase_size_flag(size_flag))<0)
        return -1;
    
    int size = fsize*fsize/8;
    oppersite(ch, chtmp, size);
    if(ioctl(fd, SET_LCD_PAGE, &pag)<0)
        return -1;
    if(ioctl(fd, SET_LCD_COLUMN, &col)<0)
        return -1;
    if(write(fd, chtmp, size)<0)
        return -1;
    return 0;
}
/*显示一个字符
ch:字符的16进制数组
pag:第几页;0-7
col:第几列;0-127
size_flag:字体枚举
*/
int show_ch(int fd, const char* ch, int pag, int col, int size_flag)
{
    if(!ch)
        return -1;    
    
    int fsize;
    if((fsize=prase_size_flag(size_flag))<0)
        return -1;
        
    int size = fsize*fsize/8;
    if(ioctl(fd, SET_LCD_PAGE, &pag)<0)
        return -1;
    if(ioctl(fd, SET_LCD_COLUMN, &col)<0)
        return -1;
    if(write(fd, ch, size)<0)
        return -1;
    return 0;
}

/*显示一行字符串*/
int show_str(int fd, const char** str, int count, int pag, int col, int size_flag)
{
    int fsize;
    int i;
    if((fsize=prase_size_flag(size_flag))<0)
        return -1;
        
    for(i=0; i<count; i++)
    {
        if(pag<PAGE_COUNT && col<COLUMN_COUNT)
        {
            if(show_ch(fd, str[i], pag, col, size_flag)<0)
                return -1;            
            col+=fsize;        
        }
    }
    return 0;
}

/*显示一行选中的字符串*/
int show_select_str(int fd, const char** str, int count, int pag, int col, int size_flag)
{
    int fsize;
    int i;
    if((fsize=prase_size_flag(size_flag))<0)
        return -1;
        
    for(i=0; i<count; i++)
    {
        if(pag<PAGE_COUNT && col<COLUMN_COUNT)
        {
            if(show_select_ch(fd, str[i], pag, col, size_flag)<0)
                return -1;            
            col+=fsize;        
        }
    }
    return 0;
}

/*对比度调节0-62*/
int contrast_ctrl(int fd, int val)
{
    if(ioctl(fd,CONTRAST_SETTING,&val)<0)
        return -1;
    return 0;
}

/*背光调节 1:亮，0:灭*/
int backlight_ctrl(int fd,int val)
{
    if(ioctl(fd, BACKLIGHT_CTRL, &val)<0)
        return -1;
    return 0;
}

/*清屏*/
int clear_screen(int fd, int val)
{
    if(ioctl(fd, CLR_SCREEN, &val)<0)
        return -1;
    return 0;
}


/*字体大小*/
int font_size(int fd, int val)
{
    if(ioctl(fd, SET_FONT_SIZE, &val)<0)
        return -1;
    return 0;
}

int main(void)
{
    fd = open(LCD_DEV_NAME,O_RDWR);
    show_ch(fd, zi, 0, 0, 1);
    show_select_ch(fd, zi, 0, 32, 1);
    show_str(fd, tmp, 8, 2, 0, 1);    
    show_select_str(fd, tmp, 8, 4, 0, 1);    
    close(fd);
}