内核自带的驱动LCD，drivers/video/Fbmem.c
LCD驱动程序
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];
以次设备号为下标。
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)
1. registered_fb在哪里被设置？
答. 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
fbmem.c都是抽象出来的，最终都得依赖于底层的驱动。
VCLK 看手册，给合适的频率
VLINE--HYSNC 行同步信号
VFRAM--VSYNC 帧同步信号
VDEN（video date enable） 颜色
硬件操作：根据LCD手册，设置LCD控制器；
分配显存，并把地址告诉LCD控制器
配置引脚用于LCD
初始化：
/* 1. 分配一个fb_info */
/* 2. 设置 */
/* 2.1 设置固定的参数 */
/* 2.2 设置可变的参数 */
/* 2.3 设置操作函数 */
/* 2.4 其他的设置 */
/* 3. 硬件相关的操作 */
/* 3.1 配置GPIO用于LCD */
/* 3.2 根据LCD手册设置LCD控制器, 比如VCLK的频率等 */
/* 3.3 分配显存(framebuffer), 并把地址告诉LCD控制器 */
/* 4. 注册 */
我们看到的图像是从左到右，从上到下
测试：配置内核
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:
具体驱动程序代码：
#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 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[];
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[]; /* 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;
} 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 ;
} static int lcd_init(void)
{
/* 1. 分配一个fb_info */
s3c_lcd = framebuffer_alloc(, NULL); /* 2. 设置 */
/* 2.1 设置固定的参数 */
strcpy(s3c_lcd->fix.id, "mylcd");
s3c_lcd->fix.smem_len = **/;
s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS;
s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR; /* TFT */
s3c_lcd->fix.line_length = *; /* 2.2 设置可变的参数 */
s3c_lcd->var.xres = ;
s3c_lcd->var.yres = ;
s3c_lcd->var.xres_virtual = ;
s3c_lcd->var.yres_virtual = ;
s3c_lcd->var.bits_per_pixel = ; /* RGB:565 */
s3c_lcd->var.red.offset = ;
s3c_lcd->var.red.length = ; 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; /* 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 = **/; /* 3. 硬件相关的操作 */
/* 3.1 配置GPIO用于LCD */
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 */
lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs)); /* 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<<); #if 1
/* 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
* LCD手册 T0-T2-T1=4
* VBPD=3
* bit[23:14]: 多少行, 320, 所以LINEVAL=320-1=319
* bit[13:6] : VFPD, 发出最后一行数据之后，再过多长时间才发出VSYNC
* LCD手册T2-T5=322-320=2, 所以VFPD=2-1=1
* bit[5:0] : VSPW, VSYNC信号的脉冲宽度, LCD手册T1=1, 所以VSPW=1-1=0
*/
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
* LCD手册 T6-T7-T8=17
* HBPD=16
* bit[18:8]: 多少列, 240, 所以HOZVAL=240-1=239
* 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
* LCD手册T8-T11=251-240=11, 所以HFPD=11-1=10
*/
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=5-1=4
*/
lcd_regs->lcdcon4 = ; #else
lcd_regs->lcdcon2 = S3C2410_LCDCON2_VBPD() | \
S3C2410_LCDCON2_LINEVAL() | \
S3C2410_LCDCON2_VFPD() | \
S3C2410_LCDCON2_VSPW(); lcd_regs->lcdcon3 = S3C2410_LCDCON3_HBPD() | \
S3C2410_LCDCON3_HOZVAL() | \
S3C2410_LCDCON3_HFPD(); lcd_regs->lcdcon4 = S3C2410_LCDCON4_MVAL() | \
S3C2410_LCDCON4_HSPW(); #endif
/* 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 = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL); lcd_regs->lcdsaddr1 = (s3c_lcd->fix.smem_start >> ) & ~(<<);
lcd_regs->lcdsaddr2 = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> ) & 0x1fffff;
lcd_regs->lcdsaddr3 = (*/); /* 一行的长度(单位: 2字节) */ //s3c_lcd->fix.smem_start = xxx; /* 显存的物理地址 */
/* 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); return ;
} static void lcd_exit(void)
{
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);
} module_init(lcd_init);
module_exit(lcd_exit); MODULE_LICENSE("GPL");
LCD Code
insmod cfbcopyarea.ko
insmod cfbfillrect.ko
insmod cfbimgblt.ko
insmod lcd.ko
还有一种是系统自带的LCD驱动程序，使用分层分离所写，再来学习！