VDEN 使能信号
HSYNC 水平方向的同步信号
VSYNC 垂直方向的同步信号
LED-/LED+ 背光信号
VCLK 时钟信号
VD0~VD23 数字信号
GPB0输出为1
驱动程序中：
lcd_init:
---------------------------------------------------------
static struct fb_info *s3c_lcd; //定义一个结构体
/* 1. 分配一个fb_info */
s3c_lcd = framebuffer_alloc(, NULL); //不需要额外的空间
--------------------3.4.2内核中的函数-----------------------------------------
struct fb_info {
struct fb_var_screeninfo var; /* Current var可变参数 */
struct fb_fix_screeninfo fix; /* Current fix 固定参数*/
struct fb_ops *fbops; /*操作参数*/
void *pseudo_palette; /* Fake palette of 16 colors 其他设置*/
unsigned long screen_size; /* Amount of ioremapped VRAM or 0显存的大小 */
}
-----------------------------------------------------------------------------
/* 2. 设置 */
/* 2.1 设置固定的参数 */
strcpy(s3c_lcd->fix.id, "mylcd"); //名字
s3c_lcd->fix.smem_len = **/; //显存的长度
s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS; //看不懂默认0
s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR; /* TFT (真彩色)*/
s3c_lcd->fix.line_length = *; //长度*2个字节
--------------------3.4.2内核中的函数-----------------------------------------
struct fb_fix_screeninfo {
char id[]; /* identification string eg "TT Builtin" */
unsigned long smem_start; /* Start of frame buffer mem */
/* (physical address) */
__u32 smem_len; /* Length of frame buffer mem */
__u32 type; /* see FB_TYPE_* */
__u32 type_aux; /* Interleave for interleaved Planes */
__u32 visual; /* see FB_VISUAL_* */
__u16 xpanstep; /* zero if no hardware panning */
__u16 ypanstep; /* zero if no hardware panning */
__u16 ywrapstep; /* zero if no hardware ywrap */
__u32 line_length; /* length of a line in bytes */
unsigned long mmio_start; /* Start of Memory Mapped I/O */
/* (physical address) */
__u32 mmio_len; /* Length of Memory Mapped I/O */
__u32 accel; /* Indicate to driver which */
/* specific chip/card we have */
__u16 capabilities; /* see FB_CAP_* */
__u16 reserved[]; /* Reserved for future compatibility */
};
---------------------------------------------------------------------
/* 2.2 设置可变的参数 */
s3c_lcd->var.xres = ; //x方向的分辨率
s3c_lcd->var.yres = ; //y方向的分辨率
s3c_lcd->var.xres_virtual = ; //x方向的虚拟分辨率
s3c_lcd->var.yres_virtual = ; //y方向的虚拟分辨率
s3c_lcd->var.bits_per_pixel = ; //每个像素用多少位
/* RGB:565 */
s3c_lcd->var.red.offset = ; //从那位开始
s3c_lcd->var.red.length = ; //长度
s3c_lcd->var.green.offset = ;
s3c_lcd->var.green.length = ;
s3c_lcd->var.blue.offset = ;
s3c_lcd->var.blue.length = ;
s3c_lcd->var.activate = FB_ACTIVATE_NOW;--------------------3.4.2内核中的函数-----------------------------------------
struct fb_var_screeninfo {
__u32 xres; /* visible resolution */
__u32 yres;
__u32 xres_virtual; /* virtual resolution */
__u32 yres_virtual;
__u32 xoffset; /* offset from virtual to visible */
__u32 yoffset; /* resolution */
__u32 bits_per_pixel; /* guess what */
__u32 grayscale; /* 0 = color, 1 = grayscale, */
/* >1 = FOURCC */
struct fb_bitfield red; /* bitfield in fb mem if true color, */
struct fb_bitfield green; /* else only length is significant */
struct fb_bitfield blue;
struct fb_bitfield transp; /* transparency */
__u32 nonstd; /* != 0 Non standard pixel format */
__u32 activate; /* see FB_ACTIVATE_* */
__u32 height; /* height of picture in mm */
__u32 width; /* width of picture in mm */
__u32 accel_flags; /* (OBSOLETE) see fb_info.flags */
/* Timing: All values in pixclocks, except pixclock (of course) */
__u32 pixclock; /* pixel clock in ps (pico seconds) */
__u32 left_margin; /* time from sync to picture */
__u32 right_margin; /* time from picture to sync */
__u32 upper_margin; /* time from sync to picture */
__u32 lower_margin;
__u32 hsync_len; /* length of horizontal sync */
__u32 vsync_len; /* length of vertical sync */
__u32 sync; /* see FB_SYNC_* */
__u32 vmode; /* see FB_VMODE_* */
__u32 rotate; /* angle we rotate counter clockwise */
__u32 colorspace; /* colorspace for FOURCC-based modes */
__u32 reserved[]; /* Reserved for future compatibility */
};
---------------------------------------------------------------------
/* 2.3 设置操作函数 */
s3c_lcd->fbops = &s3c_lcdfb_ops;
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,
};
/* 2.4 其他的设置 */
static u32 pseudo_palette[]; //定义
s3c_lcd->pseudo_palette = pseudo_palette; //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 ;
}
/* from pxafb.c */
static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
chan &= 0xffff;
chan >>= - bf->length;
return chan << bf->offset;
}
//s3c_lcd->screen_base = ; /* 显存的虚拟地址 */
s3c_lcd->screen_size = **/; //显存的大小
/* 3. 硬件相关的操作 */
/* 3.1 配置GPIO用于LCD */
/*定义*/
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;
gpbcon = ioremap(0x56000010, );
gpbdat = gpbcon+;
gpccon = ioremap(0x56000020, );
gpdcon = ioremap(0x56000030, );
gpgcon = ioremap(0x56000060, );
*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 &= ~(); /* GPB0设置为输出引脚 */
*gpbcon |= ;
*gpbdat &= ~; /* 输出低电平 */
*gpgcon |= (<<); /* 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 */
static volatile struct lcd_regs* lcd_regs; //定义
lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));
/*****LCD寄存器*****/
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;
};
/* bit[17:8]: VCLK = HCLK / [(CLKVAL+1) x 2], LCD手册P14
* 10MHz(100ns) = 100MHz / [(CLKVAL+1) x 2]
* CLKVAL = 4
* bit[6:5]: 0b11, TFT LCD
* bit[4:1]: 0b1100, 16 bpp for TFT
* bit[0] : 0 = Disable the video output and the LCD control signal.
*/
lcd_regs->lcdcon1 = (<<) | (<<) | (0x0c<<);
/* 垂直方向的时间参数
* bit[31:24]: VBPD, VSYNC之后再过多长时间才能发出第1行数据
* 4.3寸液晶屏手册
* VBPD=1 tvb=2
* bit[23:14]: 多少行, 272, 所以LINEVAL=272-1=271 tvd=272
* bit[13:6] : VFPD, 发出最后一行数据之后，再过多长时间才发出VSYNC
* 4.3寸液晶屏手册 VFPD=2-1=1 tvf=2
* bit[5:0] : VSPW, VSYNC信号的脉冲宽度, VSPW=10-1=9 tvp=10
*/
lcd_regs->lcdcon2 = (<<) | (<<) | (<<) | ();
/* 水平方向的时间参数
* bit[25:19]: HBPD, VSYNC之后再过多长时间才能发出第1行数据
* 4.3寸液晶屏手册
* HBPD=1 thb=2
* bit[18:8]: 多少列,480, 所以HOZVAL=480-1=479 thd=480
* bit[7:0] : HFPD, 发出最后一行里最后一个象素数据之后，再过多长时间才发出HSYNC
* 4.3寸液晶屏手册 HFPD=2-1=1 thf=2
*/
lcd_regs->lcdcon3 = (<<) | (<<) | ();
/* 水平方向的同步信号
* bit[7:0] : HSPW, HSYNC信号的脉冲宽度, LCD手册T7=5, 所以HSPW=41-1=40
*/
lcd_regs->lcdcon4 = ;
/* 信号的极性
* bit[11]: 1=565 format
* bit[10]: 0 = The video data is fetched at VCLK falling edge
* bit[9] : 1 = HSYNC信号要反转,即低电平有效
* bit[8] : 1 = VSYNC信号要反转,即低电平有效
* bit[6] : 0 = VDEN不用反转
* bit[3] : 0 = PWREN输出0
* bit[1] : 0 = BSWP
* bit[0] : 1 = HWSWP 2440手册P413
*/
lcd_regs->lcdcon5 = (<<) | (<<) | (<<) | (<<) | (<<);
/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
//s3c_lcd->screen_base /* 显存的虚拟地址 */
//s3c_lcd->fix.smem_start = xxx; /* 显存的物理地址 */
s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);
/*帧缓冲开始地址1寄存器
*
*/
lcd_regs->lcdsaddr1 = (s3c_lcd->fix.smem_start >> ) & ~(<<); //1~30，开始地址
lcd_regs->lcdsaddr2 = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> ) & 0x1fffff; //从1开始，结束地址
lcd_regs->lcdsaddr3 = (*/); /* 一行的长度(单位: 2字节) */
/* 启动LCD */
lcd_regs->lcdcon1 |= (<<); /* 使能LCD控制器 */
lcd_regs->lcdcon5 |= (<<); /* 使能LCD本身 */
*gpbdat |= ; /* 输出高电平, 使能背光 */
/* 4. 注册 */
register_framebuffer(s3c_lcd);
-------------------------------------------------------------------
lcd_exit:
unregister_framebuffer(s3c_lcd);
lcd_regs->lcdcon1 &= ~(<<); /* 关闭LCD本身 */
*gpbdat &= ~; /* 关闭背光 */
dma_free_writecombine(NULL, s3c_lcd->fix.smem_len, s3c_lcd->screen_base, s3c_lcd->fix.smem_start);
iounmap(lcd_regs);
iounmap(gpbcon);
iounmap(gpccon);
iounmap(gpdcon);
iounmap(gpgcon);
framebuffer_release(s3c_lcd);假设
app: open("/dev/fb0", ...) 主设备号: 29, 次设备号: 0
--------------------------------------------------------------
kernel:
fb_open
int fbidx = iminor(inode);
struct fb_info *info = = registered_fb[0];
app: read()
---------------------------------------------------------------
kernel:
fb_read
int fbidx = iminor(inode);
struct fb_info *info = registered_fb[fbidx];
if (info->fbops->fb_read)
return info->fbops->fb_read(info, buf, count, ppos);
src = (u32 __iomem *) (info->screen_base + p);
dst = buffer;
*dst++ = fb_readl(src++);
copy_to_user(buf, buffer, c)
问1. registered_fb在哪里被设置？
答1. register_framebuffer
怎么写LCD驱动程序？
1. 分配一个fb_info结构体: framebuffer_alloc
2. 设置
3. 注册: register_framebuffer
4. 硬件相关的操作
测试：
1. make menuconfig去掉原来的驱动程序
-> Device Drivers
-> Graphics support
<M> S3C2410 LCD framebuffer support
2. make uImage
make modules
3. 使用新的uImage启动开发板:
4.
insmod cfbcopyarea.ko
insmod cfbfillrect.ko
insmod cfbimgblt.ko
insmod lcd.ko
echo hello > /dev/tty1 // 可以在LCD上看见hello
cat lcd.ko > /dev/fb0 // 花屏
5. 修改 /etc/inittab
tty1::askfirst:-/bin/sh
用新内核重启开发板
insmod cfbcopyarea.ko
insmod cfbfillrect.ko
insmod cfbimgblt.ko
insmod lcd.ko
insmod buttons.ko