TQ2440移植u-boot2016.11全过程记录-【4】LCD驱动移植并显示

TQ2440移植u-boot2016.11-LCD驱动移植并显示

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LCD初始化流程分析

u-boot的LCD初始化代码是在common/lcd.c中，我们找到lcd_init函数：

该函数功能流程为：lcd_ctrl_init初始化了LCD的硬件参数---->开辟LCD的帧缓冲(缓冲基地址保存在了gd->fs_base变量中)—>清屏—>使能LCD—>设置LCD控制台参数

lcd_ctrl_init和lcd_enable函数是u-boot抽离出的函数接口，需要根据LCD的实际情况进行底层硬件的初始化操作实现这两个函数；除此之外还需要定义一个名为panel_info的vidinfo_t结构类型变量，该结构变量保存了LCD屏幕的大小和颜色位深，用于LCD屏幕的控制台显示。

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LCD驱动移植

我的屏幕是W43，分辨率480x272，驱动编写参考的TQ2440官方的LCD屏幕驱动代码修改而来。

添加LCD的相关配置宏：
gedit include/configs/tq2440.h

末尾添加如下代码：

/*
 * LCD configuration
 */
#define CONFIG_LCD                        /* 该宏用于添加进LCD相关的编译项 */
#define LCD_BPP LCD_COLOR16               /* 每像素为16bits */
#define CONFIG_LCD_LOGO                   /* 显示LOGO */
#define CONFIG_LCD_INFO                   /* 显示用户自定义信息 */
#define CONFIG_LCD_INFO_BELOW_LOGO        /* 用户自定义信息与LOGO的位置无关 */
#define CONFIG_SYS_WHITE_ON_BLACK         /* 黑底白字 */
#define CONFIG_SYS_CONSOLE_IS_IN_ENV      /* 控制台接收自环境变量 */
#define CONFIG_CONSOLE_MUX                /* 定义该宏可支持将打印信息同时输出到串口和LCD */
#define CONFIG_CONSOLE_SCROLL_LINES 16    /* 屏幕显示总行数 */

/* 以下三个宏为我自己定义的 */
#define CONFIG_TQ2440_LCD                  /* 该宏用于将tq2440_lcd.c文件编译进来 */
#define LCD_XSIZE_TFT 480                  /* LCD行数 */
#define LCD_YSIZE_TFT 272                  /* LCD列数 */

#define MVAL      13
#define MVAL_USED 0           /* 0:each frame    1:rate by MVAL */
#define INVVDEN   1           /* 0:normal        1:inverted     */
#define BSWP      0           /* byte swap control              */
#define HWSWP     1           /* half word swap control         */

#define CONFIG_TQ2440_LCD_VBPD    1
#define CONFIG_TQ2440_LCD_VFPD    1
#define CONFIG_TQ2440_LCD_VSPW    9
#define CONFIG_TQ2440_LCD_HBPD    1
#define CONFIG_TQ2440_LCD_HFPD    1
#define CONFIG_TQ2440_LCD_HSPW    40
#define CONFIG_TQ2440_LCD_CLKVAL  4

添加tq2440的LCD文件：

gedit drivers/video/tq2440_lcd.c

粘贴进如下代码：

#include <common.h>
#include <lcd.h>
#include <asm/system.h>
#include <asm/gpio.h>
#include <asm/arch/s3c24x0_cpu.h>
#include <lcd.h>
#include <version.h>

DECLARE_GLOBAL_DATA_PTR;    /* 导入gd_t结构变量gd */

/* to get lower 21bits */
#define M5D(n) ((n) & 0x1FFFFF)

vidinfo_t panel_info =
{
    .vl_col  = LCD_XSIZE_TFT,    /* 列数 */
    .vl_row  = LCD_YSIZE_TFT,    /* 行数 */
    .vl_bpix = LCD_BPP,          /* 像素位数为16bits，该宏在tq2440.h中被定义 */
};

/* 将LCD缓冲数组转为二维数组来用 */
#define tq2440_lcd_frame_pbuf ((volatile unsigned short (*)[LCD_XSIZE_TFT])(gd->fb_base))

void tq2440_lcd_clear_screen(unsigned short color)
{
    int x = 0, y = 0;

    for (y = 0; y < LCD_YSIZE_TFT; y++)
    {
        for (x = 0; x < LCD_XSIZE_TFT; x++)
        {
            tq2440_lcd_frame_pbuf[y][x] = color;
        }
    }
}

void lcd_ctrl_init(void* lcdbase)
{
    char vbpd = 0;
    char vfpd = 0;
    char vspw = 0;
    char hbpd = 0;
    char hfpd = 0;
    char hspw = 0;
    char clkval = 0;
    char* lcdenv = NULL;
    struct s3c24x0_gpio* const gpio = s3c24x0_get_base_gpio();
    struct s3c24x0_lcd*  const lcd  = s3c24x0_get_base_lcd();

    /* set lcd frame buffer start adddress */
    lcd->lcdsaddr1 = (((unsigned int)tq2440_lcd_frame_pbuf >> 22) << 21) | M5D((unsigned int)tq2440_lcd_frame_pbuf >> 1);

    /* set lcd frame buffer end adddress */
    lcd->lcdsaddr2 = M5D(((unsigned int)tq2440_lcd_frame_pbuf + (LCD_XSIZE_TFT * LCD_YSIZE_TFT * 2)) >> 1);

    /* set virtul screen page wigth */
    lcd->lcdsaddr3 = (((LCD_XSIZE_TFT - LCD_XSIZE_TFT) / 1) << 11) | (LCD_XSIZE_TFT / 1);

    lcdenv = getenv("dwVBPD");
    vbpd = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_VBPD;

    lcdenv = getenv("dwVFPD");
    vfpd = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_VFPD;

    lcdenv = getenv("dwVSPW");
    vspw = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_VSPW;

    lcdenv = getenv("dwHBPD");
    hbpd = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_HBPD;

    lcdenv = getenv("dwHFPD");
    hfpd = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_HFPD;

    lcdenv = getenv("dwHSPW");
    hspw = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_HSPW;

    lcdenv = getenv("dwCLKVAL");
    clkval = lcdenv ? (int)simple_strtol(lcdenv, NULL, 10) : CONFIG_TQ2440_LCD_CLKVAL;

    /* clear screen */
    tq2440_lcd_clear_screen(0x0000);

	/* initialize VD[7:0] */
	gpio->gpcup  = 0xFFFFFFFF;
	gpio->gpccon = 0xAAAAAAAA;

	/* initialize VD[15:8] */
	gpio->gpdup  = 0xFFFFFFFF;
	gpio->gpdcon = 0xAAAAAAAA;
	
    /* lcd config */
    lcd->lcdcon1 = (clkval << 8) | (MVAL_USED << 7) | (3 << 5) | (12 << 1) | 0;
    lcd->lcdcon2 = (vbpd << 24) | ((LCD_YSIZE_TFT - 1) << 14) | (vfpd << 6) | vspw;
    lcd->lcdcon3 = (hbpd << 19) | ((LCD_XSIZE_TFT - 1) << 8) | hfpd;
    lcd->lcdcon4 = (MVAL << 8) | hspw;
    lcd->lcdcon5 = (1 << 11) | (0 << 10) | (1 << 9) | (1 << 8) | (0 << 7) | (0 << 6) | (1 << 3) | (BSWP << 1) | HWSWP;

    /* make lcd sub interrupt */
    lcd->lcdintmsk |= 0x3;

    /* disable lpc3480 */
    lcd->lpcsel &= ~(0x7);

    /* disbale temp palette */
    lcd->tpal = 0x0;

    /* disable gpg4 pull-up */
    gpio->gpgup &= ~(1 << 4);

    /* set gpg4 mode to lcd_pwrdn */
    gpio->gpgcon |= 3 << 8;

    /* set gpg4 to high */
    gpio->gpgdat |= 1 << 4;

    /* enable pwren signal */
    lcd->lcdcon5 |= 1 << 3;

    /* set signal polarity to normal */
    lcd->lcdcon5 &= ~(1 << 5);
}

void lcd_enable(void)
{
	struct s3c24x0_lcd* const lcd = s3c24x0_get_base_lcd();

	/* Enable the video output and the LCD control signal. */
	lcd->lcdcon1 |= (1 << 0);
}

#ifdef CONFIG_LCD_INFO
void lcd_show_board_info(void)
{
	lcd_printf("%s (%s - %s)\n", U_BOOT_VERSION, U_BOOT_DATE, U_BOOT_TIME);
}
#endif

添加进编译项：
gedit drivers/video/Makefile

末尾添加一行：

obj-$(CONFIG_TQ2440_LCD) += tq2440_lcd.o

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测试

编译后使用tftp下载到内存0x30008000处并运行程序，查看效果：

下面操作将输出信息重定向到LCD上显示：

使用以下命令查看可以将输出信息重定向到哪些设备：
coninfo

可以看到可以将输出信息重定向到串口和LCD，serial就是我们使用的串口一，标志为IO，也就是说可以输入输出，LCD为.O，也就是说只能输出不能输入。

将输出信息同时重定向到LCD和串口一：

setenv stdout 'lcd,serial'

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