linux中LCD设备驱动（4）——基于s3c6410平台

我们这一篇来说与具体的TFT显示器有关的部分，当遇到具体的显示器是我们应该设置什么参数，怎样设置这些参数。

1、在s3cfb_WXCAT43.c (linux2.6.28driversvideosamsung）文件中是有关具体显示器的设置。我们一段一段来看。

#include

#include

#include

#include

#include

#include

#include "s3cfb.h"

#define S3CFB_HFP 2/* front porch */

#define S3CFB_HSW 41/* hsync width */

#define S3CFB_HBP 2/* back porch */

#define S3CFB_VFP 2/* front porch */

#define S3CFB_VSW 10/* vsync width */

#define S3CFB_VBP 2/* back porch */

#define S3CFB_HRES 480/* horizon pixel  x resolition */

#define S3CFB_VRES 272/* line cnt       y resolution */

#define S3CFB_HRES_VIRTUAL 480/* horizon pixel  x resolition */

#define S3CFB_VRES_VIRTUAL 544/* line cnt       y resolution */

#define S3CFB_HRES_OSD 480/* horizon pixel  x resolition */

#define S3CFB_VRES_OSD 272/* line cnt       y resolution */

#define S3CFB_VFRAME_FREQ     60/* frame rate freq */

#define S3CFB_PIXEL_CLOCK (S3CFB_VFRAME_FREQ * (S3CFB_HFP + S3CFB_HSW + S3CFB_HBP + S3CFB_HRES) * (S3CFB_VFP + S3CFB_VSW + S3CFB_VBP + S3CFB_VRES))这个不太明白是干嘛用的？

那么上面这些参数的值是在那里得到的呢？那就要看具体的显示器的手册了。如下所示：

2、在这个文件中，还有两个函数，源码如下：

void s3cfb_init_hw(void)

{

printk(KERN_INFO "LCD TYPE :: LTE480WV will be initializedn");

s3cfb_set_fimd_info();

s3cfb_set_gpio();

}

这个函数在s3cfb_init_fbinfo函数中被调用，其实就是在LCD对应的probe函数中被调用。

static void s3cfb_init_fbinfo(s3cfb_info_t *finfo, char *drv_name, int index)

{

int i = 0;

if (index == 0)

s3cfb_init_hw();

.........

｝

2.1、现在来分析s3cfb_set_fimd_info函数，源码如下：

static void s3cfb_set_fimd_info(void)

{

s3cfb_fimd.vidcon1 = S3C_VIDCON1_IHSYNC_INVERT | S3C_VIDCON1_IVSYNC_INVERT | S3C_VIDCON1_IVDEN_NORMAL;

其中有#define S3C_VIDCON1_IHSYNC_INVERT(1<<6)

      #define S3C_VIDCON1_IVSYNC_INVERT(1 << 5)

      #define S3C_VIDCON1_IVDEN_NORMAL(0<<4)

看下图：

        s3cfb_fimd.vidtcon0 = S3C_VIDTCON0_VBPD(S3CFB_VBP - 1) | S3C_VIDTCON0_VFPD(S3CFB_VFP - 1) | S3C_VIDTCON0_VSPW(S3CFB_VSW - 1);

        其中有： /*  VIDEO Time Control 0 register - VIDTCON0 */

 #define S3C_VIDTCON0_VBPDE(x) (((x)&0xFF)<<24)

 #define S3C_VIDTCON0_VBPD(x) (((x)&0xFF)<<16)

 #define S3C_VIDTCON0_VFPD(x) (((x)&0xFF)<<8)

 #define S3C_VIDTCON0_VSPW(x) (((x)&0xFF)<<0)

        s3cfb_fimd.vidtcon1 = S3C_VIDTCON1_HBPD(S3CFB_HBP - 1) | S3C_VIDTCON1_HFPD(S3CFB_HFP - 1) | S3C_VIDTCON1_HSPW(S3CFB_HSW - 1);

s3cfb_fimd.vidtcon2 = S3C_VIDTCON2_LINEVAL(S3CFB_VRES - 1) | S3C_VIDTCON2_HOZVAL(S3CFB_HRES - 1);

s3cfb_fimd.vidosd0a = S3C_VIDOSDxA_OSD_LTX_F(0) | S3C_VIDOSDxA_OSD_LTY_F(0);

s3cfb_fimd.vidosd0b = S3C_VIDOSDxB_OSD_RBX_F(S3CFB_HRES - 1) | S3C_VIDOSDxB_OSD_RBY_F(S3CFB_VRES - 1);

s3cfb_fimd.vidosd1a = S3C_VIDOSDxA_OSD_LTX_F(0) | S3C_VIDOSDxA_OSD_LTY_F(0);

s3cfb_fimd.vidosd1b = S3C_VIDOSDxB_OSD_RBX_F(S3CFB_HRES_OSD - 1) | S3C_VIDOSDxB_OSD_RBY_F(S3CFB_VRES_OSD - 1);

这些也和上面一样的，对照手册，设置就可以了。

s3cfb_fimd.width = S3CFB_HRES;  屏幕的大小信息

s3cfb_fimd.height = S3CFB_VRES;

s3cfb_fimd.xres = S3CFB_HRES;

s3cfb_fimd.yres = S3CFB_VRES;

#if defined(CONFIG_FB_S3C_VIRTUAL_SCREEN)  与虚拟屏有关

s3cfb_fimd.xres_virtual = S3CFB_HRES_VIRTUAL;

s3cfb_fimd.yres_virtual = S3CFB_VRES_VIRTUAL;

#else

s3cfb_fimd.xres_virtual = S3CFB_HRES;

s3cfb_fimd.yres_virtual = S3CFB_VRES;

#endif

s3cfb_fimd.osd_width = S3CFB_HRES_OSD; 还记得上一篇中OSD的含义吗？

s3cfb_fimd.osd_height = S3CFB_VRES_OSD;

s3cfb_fimd.osd_xres = S3CFB_HRES_OSD;

s3cfb_fimd.osd_yres = S3CFB_VRES_OSD;

s3cfb_fimd.osd_xres_virtual = S3CFB_HRES_OSD;

s3cfb_fimd.osd_yres_virtual = S3CFB_VRES_OSD;

s3cfb_fimd.pixclock = S3CFB_PIXEL_CLOCK;

s3cfb_fimd.hsync_len = S3CFB_HSW;

s3cfb_fimd.vsync_len = S3CFB_VSW;

s3cfb_fimd.left_margin = S3CFB_HFP;

s3cfb_fimd.upper_margin = S3CFB_VFP;

s3cfb_fimd.right_margin = S3CFB_HBP;

s3cfb_fimd.lower_margin = S3CFB_VBP;

}

2.2、接着分析另外一个函数s3cfb_set_gpio()，这个函数的源码如下：

int s3cfb_set_gpio(void)

{

unsigned long val;

int i, err;

/* Must be '0' for Normal-path instead of By-pass */

writel(0x0, S3C_HOSTIFB_MIFPCON);

其中有：#define S3C_HOSTIFB_MIFPCONS3C_HOSTIFBREG(0x800C)

       #define S3C_HOSTIFAREG(x)((x) + S3C64XX_VA_HOSTIFA)

同时在s3c6410的手册上有这么一句话：

Caution 1: In normal display mode, SEL_BYPASS@ MIFPCON (0x7410_800C) register must be set “0”.

/* enable clock to LCD */使能LCD的时钟

val = readl(S3C_HCLK_GATE);

val |= S3C_CLKCON_HCLK_LCD;

writel(val, S3C_HCLK_GATE);

/* phantom */也和时钟有关

val = readl(S3C_SCLK_GATE);

val |= (1<<14);

writel(val, S3C_SCLK_GATE);

/* ------- */

/* select TFT LCD type (RGB I/F) */设置RGB的数据格式

val = readl(S3C64XX_SPC_BASE);

val &= ~0x3;

val |= (1 << 0);

writel(val, S3C64XX_SPC_BASE);

其中有：#define S3C64XX_SPC_BASE(S3C64XX_VA_GPIO + 0x01A0)

这个参数的设置，和具体的TFT屏有关，在TFT屏的手册中有：24bit RGB Interface

/* VD */主要是芯片引脚的设置，看下图：不过你可能对s3c_gpio_cfgpin函数不明白，它是怎样实现的，我在以前的写的一篇博客中有说明，你可以去查看，本篇后面我会给出链接地址。

for (i = 0; i < 16; i++)

s3c_gpio_cfgpin(S3C64XX_GPI(i), S3C_GPIO_SFN(2));

for (i = 0; i < 12; i++)

s3c_gpio_cfgpin(S3C64XX_GPJ(i), S3C_GPIO_SFN(2));

#ifndef CONFIG_BACKLIGHT_PWM  

/* backlight ON */

//printk("oPEN LCD BACKLIGHT1.n");   和LCD背光灯有关，看下面的图：

        if (gpio_is_valid(S3C64XX_GPF(14))) {              //NOTE: orign GPF15 here

err = gpio_request(S3C64XX_GPF(14), "GPF");

if (err) {

printk(KERN_ERR "failed to request GPF for "

"lcd backlight controln");

return err;

}

gpio_direction_output(S3C64XX_GPF(14), 1);

gpio_set_value(S3C64XX_GPF(14), 1);

}

#endif

//printk("oPEN LCD BACKLIGHT2.n");

         if (gpio_is_valid(S3C64XX_GPE(0))) {

err = gpio_request(S3C64XX_GPE(0), "GPE");

if (err) {

printk(KERN_ERR "failed to request GPE for "

"lcd reset controln");

return err;

}

gpio_direction_output(S3C64XX_GPE(0), 1);

}

gpio_set_value(S3C64XX_GPE(0), 1);

gpio_free(S3C64XX_GPE(0));

/* module reset */

/*if (gpio_is_valid(S3C64XX_GPN(5))) {

err = gpio_request(S3C64XX_GPN(5), "GPN");

if (err) {

printk(KERN_ERR "failed to request GPN for "

"lcd reset controln");

return err;

}

gpio_direction_output(S3C64XX_GPN(5), 1);

}

mdelay(100);

gpio_set_value(S3C64XX_GPN(5), 0);

mdelay(10);

gpio_set_value(S3C64XX_GPN(5), 1);

mdelay(10);

*/

#ifndef CONFIG_BACKLIGHT_PWM

gpio_free(S3C64XX_GPF(14));

#endif

//gpio_free(S3C64XX_GPN(5));

return 0;

}

在这个函数出现了许多对GPIO操作的函数，如：s3c_gpio_cfgpin，gpio_direction_output等等，你可能不熟悉这些，下面这个地址链接对这些讲解的很详细。