#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[9];
unsigned long dithmode;
unsigned long tpal;
unsigned long lcdintpnd;
unsigned long lcdsrcpnd;
unsigned long lcdintmsk;
unsigned long lpcsel;
};
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];
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;
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 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 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 = 240*320*16/8;
s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS;
s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR;
s3c_lcd->fix.line_length = 240*2;
// 2.2 设置可变的参数
s3c_lcd->var.xres = 240;
s3c_lcd->var.yres = 320;
s3c_lcd->var.xres_virtual = 240;
s3c_lcd->var.yres_virtual = 320;
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 = 240*324*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 / [(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 = (4<<8) | (3<<5) | (0x0c<<1);
#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 = (3<<24) | (319<<14) | (1<<6) | (0<<0);
// 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 = (16<<19) | (239<<8) | (10<<0);
// 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 = 4;
#else
lcd_regs->lcdcon2 = S3C2410_LCDCON2_VBPD(5) |
S3C2410_LCDCON2_LINeval_r(319) |
S3C2410_LCDCON2_VFPD(3) |
S3C2410_LCDCON2_VSPW(1);
lcd_regs->lcdcon3 = S3C2410_LCDCON3_HBPD(10) |
S3C2410_LCDCON3_HOZVAL(239) |
S3C2410_LCDCON3_HFPD(1);
lcd_regs->lcdcon4 = S3C2410_LCDCON4_MVAL(13) |
S3C2410_LCDCON4_HSPW(0);
#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 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);
// 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 >> 1) & ~(3<<30);
lcd_regs->lcdsaddr2 = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> 1) & 0x1fffff;
lcd_regs->lcdsaddr3 = (240*16/16); // 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 |= (1<<0); // 使能LCD控制器
lcd_regs->lcdcon5 |= (1<<3); // 使能LCD本身
*gpbdat |= 1; // 输出高电平, 使能背光
// 4. 注册
register_framebuffer(s3c_lcd);
return 0;
}
static void lcd_exit(void)
{
unregister_framebuffer(s3c_lcd);
lcd_regs->lcdcon1 &= ~(1<<0); // 关闭LCD本身
*gpbdat &= ~1; // 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");
============================================================
解析：
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];
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
S3C2410 LCD framebuffer support
2. make uImage
make modules
之后会在内核的linux-2.6.22.6/drivers/video目录下生成：
cfbcopyarea.ko
cfbfillrect.ko
cfbimgblt.ko
拷贝到lcd.ko所在目录下即可。
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
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