嵌入式Linux驱动学习之路(十八)LCD驱动

驱动代码：

/*************************************************************************
    > File Name: lcd.c
    > Author:
    > Mail:
    > Created Time: 2016年11月02日 星期三 15时21分59秒
 ************************************************************************/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/wait.h>
#include <linux/platform_device.h>
#include <linux/clk.h>

#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/div64.h>

#include <asm/mach/map.h>
#include <asm/arch/regs-lcd.h>
#include <asm/arch/regs-gpio.h>
#include <asm/arch/fb.h>

static volatile unsigned long *gpbcon;
static volatile unsigned long *gpbdat;

static volatile unsigned long *gpccon;
static volatile unsigned long *gpdcon;
static volatile unsigned long *gpgcon;

struct lcd_regs {
    unsigned long lcdcon1;
    unsigned long lcdcon2;
    unsigned long lcdcon3;
    unsigned long lcdcon4;
    unsigned long lcdcon5;
    unsigned long lcdsaddr1;
    unsigned long lcdsaddr2;
    unsigned long lcdsaddr3;
    unsigned long redlut;
    unsigned long greenlut;
    unsigned long bluelut;
    unsigned long reserved[];
    unsigned long dithmode;
    unsigned long tpal;
    unsigned long lcdintpnd;
    unsigned long lcdsrcpnd;
    unsigned long lcdintmsk;
    unsigned long lpcsel;
};

static int s3c_lcdfb_setcolreg( unsigned int regno, unsigned int red, unsigned int green, unsigned int blue, unsigned int transp, struct fb_info *info );
static u32 pseudo_palette[];
static volatile struct lcd_regs *lcd_reg;  

static struct fb_info *s3c_fb;

static struct fb_ops s3c_fb_ops = {
        .owner= THIS_MODULE,
        .fb_setcolreg= s3c_lcdfb_setcolreg,
        .fb_fillrect= cfb_fillrect,   /* Needed !!! */
        .fb_copyarea= cfb_copyarea,/* Needed !!! */
        .fb_imageblit= cfb_imageblit,/* Needed !!! */
};

static unsigned int chan_to_field(unsigned int chan, const struct fb_bitfield *bf)
{
    chan &= 0xffff;
    chan >>=  - bf->length;
    return chan << bf->offset;
}

/*调色板*/
static int s3c_lcdfb_setcolreg( unsigned int regno, unsigned int red, unsigned int green, unsigned int blue, unsigned int transp, struct fb_info *info )
{
    unsigned int val;
    if(regno >  )
        return ;
    /* 用红绿蓝构造出调色板 */
    val = chan_to_field( red, &info->var.red );
    val |= chan_to_field( green, &info->var.green );
    val |= chan_to_field( blue, &info->var.blue );
    ((u32 *)(info->pseudo_palette))[regno] = val;
    return ;
}

static int lcd_init( void )
{
    /* 分配一个fb_info结构体 */
    s3c_fb = framebuffer_alloc(,NULL);  //分配的空间为fb_info + 0 (0为私有空间)

    /* 设置 */
    /* 设置固定的参数 */
    strcpy( s3c_fb->fix.id, "mylcd" );
    s3c_fb->fix.smem_len = **/;
    s3c_fb->fix.type = FB_TYPE_PACKED_PIXELS;
    s3c_fb->fix.visual = FB_VISUAL_TRUECOLOR;   /* TFT*/
    s3c_fb->fix.line_length = *;

    /* 设置可变的参数 */
    s3c_fb->var.xres = ;
    s3c_fb->var.yres = ;
    s3c_fb->var.xres_virtual = ;
    s3c_fb->var.yres_virtual = ;
    s3c_fb->var.xres_virtual = ;
    s3c_fb->var.yres_virtual = ;
    s3c_fb->var.bits_per_pixel = ;

    s3c_fb->var.red.offset = ;
    s3c_fb->var.red.length = ;

    s3c_fb->var.green.offset = ;
    s3c_fb->var.green.length = ;

    s3c_fb->var.blue.offset = ;
    s3c_fb->var.blue.length = ;

    s3c_fb->var.activate = FB_ACTIVATE_NOW;

    /* 设置操作函数 */
    s3c_fb->fbops = &s3c_fb_ops;

    /* 其他设置 */
    s3c_fb->pseudo_palette = pseudo_palette;
    //s3c_fb->screen_base = ;           //显存的虚拟地址
    s3c_fb->screen_size = **;    //显存的大小

    /* 配置GPIO */
    gpbcon = ioremap(0x56000010,);
    gpbdat = gpbcon + ;
    gpccon = ioremap(0x56000020,);
    gpdcon = ioremap(0x56000030,);
    gpgcon = ioremap(0x56000060,);

    *gpccon = 0xaaaaaaaa;
    *gpdcon = 0xaaaaaaaa;
    *gpbcon &= ~();
    *gpbcon |= ;
    *gpbdat &= ~; //关闭背光
    *gpgcon |= (<<); 

    /* 根据lcd手册 配置lcd控制器 */
    lcd_reg = ioremap(0x4d000000, sizeof(struct lcd_regs));
    /*
     * VCLK = HCLK / ((CLKVAL+1)*2)
     *
     * */
    lcd_reg->lcdcon1 = (<<)|(<<)|(0x0c<<);
    /*
     * 垂直方向的时间参数
    * VBPD      是VSYNC之后再过多长时间才能发出第一行数据
    * LINEVAL   多少行数据 320
    * VFPD      发出最后一行数据之后过多久才发出VSYNC信号
    * VSPW      VSYNC信号的脉冲宽度
    * */
    lcd_reg->lcdcon2 = (<<)|(<<)|(<<)|();

    /*
    *  水平方向的时间参数
    *  HBPD     是HSYNC之后再过多长时间才能发出第一个像素数据
    *  HOZVAL   有多少列
    *  HFPD     发出一行的最后一个数据后再过多长时间发出HSYNC信号
    *  HSPW     HSYNC信号的脉冲宽度
    * */
    lcd_reg->lcdcon3 = (<<) | (<<) | (<<);
    lcd_reg->lcdcon4 = ;

    /*
    * 信号的极性
    * bits[11] format for 565
    * bits[10] 上升沿有效
    * bits[9]  HSYNC信号反转
    * bits[8]  VSYNC信号反转
    * bits[7]  数据
    * bits[6]  VDEN
    * bits[3]  PWREN
    * */
    lcd_reg->lcdcon5 = (<<) | (<<) | (<<) | (<<);

    /* 分配显存 */
    s3c_fb->screen_base = dma_alloc_writecombine(NULL, s3c_fb->fix.smem_len, &s3c_fb->fix.smem_start,GFP_KERNEL );
    lcd_reg->lcdsaddr1 = (s3c_fb->fix.smem_start >> ) & ~(<<);
    lcd_reg->lcdsaddr2 = ((s3c_fb->fix.smem_start + s3c_fb->fix.smem_len)>>) & 0x1fffff;
    lcd_reg->lcdsaddr3 = (*/); /* 1行的长度  单位是2字节*/

    /**/
    lcd_reg->lcdcon1 |= ;      /*使能LCD控制器*/
    lcd_reg->lcdcon5 |= (<<);   /* 使能LCD */
    *gpbdat |= ;               /*使能背光*/
    /* 注册 */
    register_framebuffer(s3c_fb);

    return ;
}

static void lcd_exit( void )
{
    unregister_framebuffer(s3c_fb);
    lcd_reg->lcdcon1 &= ~;
    *gpbdat &= ~;
    dma_free_writecombine(NULL,s3c_fb->fix.smem_len,s3c_fb->screen_base,s3c_fb->fix.smem_start);
    iounmap(lcd_reg);
    iounmap(gpbcon);
    iounmap(gpccon);
    iounmap(gpdcon);
    iounmap(gpgcon);
    framebuffer_release(s3c_fb);
}

module_init(lcd_init);
module_exit(lcd_exit);
MODULE_LICENSE("GPL");

注：这是240*320寸的屏幕。

需要在配置内核的时候不要把lcd驱动编译到内核中。

在安装驱动时会提示某些函数找不到。需要安装cfg*.ko等驱动模块。

也可以将触摸屏和按键做为控制终端。需要在 /etc/inittab中添加

tty1::askfirst:-/bin/sh
即可！

sd