LCD液晶屏驱动详解（5）

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于 2024-01-25 00:15:00 发布 · 1k 阅读

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#linux #运维 #服务器

调色板相关函数设置

为了兼容性，我们要先定义一个伪调色板数组，

static u32 pseudo_palette[16];

设置颜色填充函数

/* from pxafb.c */
static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
    chan &= 0xffff;
    chan >>= 16 - bf->length;
    return chan << bf->offset;
}

设置调色板

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 > 16)
        return 1;

    /* 用red,green,blue三原色构造出val */
    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;
    pseudo_palette[regno] = val;
    return 0;
}

lcd.c文件的整体代码结构

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/err.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 <linux/cpufreq.h>

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

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

static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
                 unsigned int green, unsigned int blue,
                 unsigned int transp, struct fb_info *info);


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[9];
    unsigned long   dithmode;
    unsigned long   tpal;
    unsigned long   lcdintpnd;
    unsigned long   lcdsrcpnd;
    unsigned long   lcdintmsk;
    unsigned long   lpcsel;
};

static struct fb_ops s3c_lcdfb_ops = {
    .owner      = THIS_MODULE,
    .fb_setcolreg   = s3c_lcdfb_setcolreg,
    .fb_fillrect    = cfb_fillrect,
    .fb_copyarea    = cfb_copyarea,
    .fb_imageblit   = cfb_imageblit,
};


static struct fb_info *s3c_lcd;
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;
static volatile struct lcd_regs* lcd_regs;
static u32 pseudo_palette[16];


/* from pxafb.c */
static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
    chan &= 0xffff;
    chan >>= 16 - bf->length;
    return chan << bf->offset;
}


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 > 16)
        return 1;

    /* 用red,green,blue三原色构造出val */
    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;
    pseudo_palette[regno] = val;
    return 0;
}

static int lcd_init(void)
{
    /* 1. 分配一个fb_info */
    s3c_lcd = framebuffer_alloc(0, NULL);

    /* 2. 设置 */
    /* 2.1 设置固定的参数 */
    strcpy(s3c_lcd->fix.id, "mylcd");
    s3c_lcd->fix.smem_len = 480*272*16/8;
    s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;
    s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR; /* TFT */
    s3c_lcd->fix.line_length = 480*2;
    
    /* 2.2 设置可变的参数 */
    s3c_lcd->var.xres           = 480;
    s3c_lcd->var.yres           = 272;
    s3c_lcd->var.xres_virtual   = 480;
    s3c_lcd->var.yres_virtual   = 272;
    s3c_lcd->var.bits_per_pixel = 16;

    /* RGB:565 */
    s3c_lcd->var.red.offset     = 11;
    s3c_lcd->var.red.length     = 5;
    
    s3c_lcd->var.green.offset   = 5;
    s3c_lcd->var.green.length   = 6;

    s3c_lcd->var.blue.offset    = 0;
    s3c_lcd->var.blue.length    = 5;

    s3c_lcd->var.activate       = FB_ACTIVATE_NOW;
    
    
    /* 2.3 设置操作函数 */
    s3c_lcd->fbops              = &s3c_lcdfb_ops;
    
    /* 2.4 其他的设置 */
    s3c_lcd->pseudo_palette = pseudo_palette;
    //s3c_lcd->screen_base  = ;  /* 显存的虚拟地址 */ 
    s3c_lcd->screen_size   = 480*272*16/8;

    /* 3. 硬件相关的操作 */
    /* 3.1 配置GPIO用于LCD */
    gpbcon = ioremap(0x56000010, 8);
    gpbdat = gpbcon+1;
    gpccon = ioremap(0x56000020, 4);
    gpdcon = ioremap(0x56000030, 4);
    gpgcon = ioremap(0x56000060, 4);

    *gpccon  = 0xaaaaaaaa;   /* GPIO管脚用于VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND */
    *gpdcon  = 0xaaaaaaaa;   /* GPIO管脚用于VD[23:8] */
    
    *gpbcon &= ~(3);  /* GPB0设置为输出引脚 */
    *gpbcon |= 1;
    *gpbdat &= ~1;     /* 输出低电平 */

    *gpgcon |= (3<<8); /* GPG4用作LCD_PWREN */
    
    /* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */
    lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));

    /* bit[17:8]: VCLK = HCLK / [(CLK