LCD驅動(輸入子系統)

#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. 分配一個fb_info

s3c_lcd = framebuffer_alloc(0, NULL);

// 2. 設置 //

// 2.1 設置固定的參數 //

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 設置可變的參數

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 設置操作函數

s3c_lcd->fbops = &s3c_lcdfb_ops;

// 2.4 其他的設置

s3c_lcd->pseudo_palette = pseudo_palette;

//s3c_lcd->screen_base = ; // 顯存的虛擬地址

s3c_lcd->screen_size = 240*324*16/8;

// 3. 硬件相關的操作

// 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管腳用于VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND

*gpdcon = 0xaaaaaaaa; // GPIO管腳用于VD[23:8]

*gpbcon &= ~(3); // GPB0設置為輸出引腳

*gpbcon |= 1;

*gpbdat &= ~1; // 輸出低電平

*gpgcon |= (3<<8); //GPG4用作LCD_PWREN

// 3.2 根據LCD手冊設置LCD控制器, 比如VCLK的頻率等

lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));

// bit[17:8]: VCLK = HCLK / [(CLKVAL+1) x 2], LCD手冊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

// 垂直方向的時間參數

* bit[31:24]: VBPD, VSYNC之后再過多長時間才能發出第1行數據

* LCD手冊 T0-T2-T1=4

* VBPD=3

* bit[23:14]: 多少行, 320, 所以LINEVAL=320-1=319

* bit[13:6] : VFPD, 發出最后一行數據之后，再過多長時間才發出VSYNC

* LCD手冊T2-T5=322-320=2, 所以VFPD=2-1=1

* bit[5:0] : VSPW, VSYNC信號的脈沖寬度, LCD手冊T1=1, 所以VSPW=1-1=0

//

lcd_regs->lcdcon2 = (3<<24) | (319<<14) | (1<<6) | (0<<0);

// 水平方向的時間參數

* bit[25:19]: HBPD, VSYNC之后再過多長時間才能發出第1行數據

* LCD手冊 T6-T7-T8=17

* HBPD=16

* bit[18:8]: 多少列, 240, 所以HOZVAL=240-1=239

* bit[7:0] : HFPD, 發出最后一行里最后一個象素數據之后，再過多長時間才發出HSYNC

* LCD手冊T8-T11=251-240=11, 所以HFPD=11-1=10

//

lcd_regs->lcdcon3 = (16<<19) | (239<<8) | (10<<0);

// 水平方向的同步信號

* bit[7:0] : HSPW, HSYNC信號的脈沖寬度, LCD手冊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

// 信號的極性

* bit[11]: 1=565 format

* bit[10]: 0 = The video data is fetched at VCLK falling edge

* bit[9] : 1 = HSYNC信號要反轉,即低電平有效

* bit[8] : 1 = VSYNC信號要反轉,即低電平有效

* bit[6] : 0 = VDEN不用反轉

* bit[3] : 0 = PWREN輸出0

* bit[1] : 0 = BSWP

* bit[0] : 1 = HWSWP 2440手冊P413

//

lcd_regs->lcdcon5 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);

// 3.3 分配顯存(framebuffer), 并把地址告訴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); // 一行的長度(單位: 2字節)

//s3c_lcd->fix.smem_start = xxx; // 顯存的物理地址

// 啟動LCD

lcd_regs->lcdcon1 |= (1<<0); // 使能LCD控制器

lcd_regs->lcdcon5 |= (1<<3); // 使能LCD本身

*gpbdat |= 1; // 輸出高電平, 使能背光

// 4. 注冊

register_framebuffer(s3c_lcd);

return 0;

}

static void lcd_exit(void)

{

unregister_framebuffer(s3c_lcd);

lcd_regs->lcdcon1 &= ~(1<<0); // 關閉LCD本身

*gpbdat &= ~1; // 關閉背光

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驅動程序

假設

app: open("/dev/fb0", ...) 主設備號: 29, 次設備號: 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)

問1. registered_fb在哪里被設置？

答1. register_framebuffer

怎么寫LCD驅動程序？

1. 分配一個fb_info結構體: framebuffer_alloc

2. 設置

3. 注冊: register_framebuffer

4. 硬件相關的操作

測試：

1. make menuconfig去掉原來的驅動程序

-> Device Drivers

-> Graphics support

S3C2410 LCD framebuffer support

2. make uImage

make modules

之后會在內核的linux-2.6.22.6/drivers/video目錄下生成：

cfbcopyarea.ko

cfbfillrect.ko

cfbimgblt.ko

拷貝到lcd.ko所在目錄下即可。

3. 使用新的uImage啟動開發板:

4.

insmod cfbcopyarea.ko

insmod cfbfillrect.ko

insmod cfbimgblt.ko

insmod lcd.ko

echo hello > /dev/tty1 // 可以在LCD上看見hello

cat lcd.ko > /dev/fb0 // 花屏

5. 修改 /etc/inittab

tty1::askfirst:-/bin/sh

用新內核重啟開發板

insmod cfbcopyarea.ko

insmod cfbfillrect.ko

insmod cfbimgblt.ko

insmod lcd.ko

insmod buttons.ko