【记录】LCD驱动

1.LCD驱动框架

1.1程序结构

打开设备
app:

open(“/dev/fb0”, …)

kernel:
fb_open
int fbidx = iminor(inode);
struct fb_info *info = = registered_fb[0];

读设备
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)

可以看到，驱动程序依赖于registered_fb结构。

2.LCD驱动

具体步骤如下：

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频率等
3.3 分配显存(framebuffer)，并把地址告诉LCD控制器

这里，硬件相关的操作需要结合2440和LCD的手册进行配置。详细情况参考韦东山老师的视频。

4.注册

3.驱动测试

1. make memuconfig去掉原来的LCD驱动程序

cd /work/system/linux-2.6.22.6/
make menuconfig

显示如下信息

scripts/kconfig/mconf arch/arm/Kconfig
drivers/serial/Kconfig:235:warning: multi-line strings not supported
 .config - Linux Kernel v2.6.22.6 Configuration
 ----------------------------------------------------------------------------------------------------
  +--------------------------------- Linux Kernel Configuration ----------------------------------+
  |  Arrow keys navigate the menu.  <Enter> selects submenus --->.  Highlighted letters are       |
  |  hotkeys.  Pressing <Y> includes, <N> excludes, <M> modularizes features.  Press <Esc><Esc>   |
  |  to exit, <?> for Help, </> for Search.  Legend: [*] built-in  [ ] excluded  <M> module  < >  |
  |  module capable                                                                               |
  | +-------------------------------------------------------------------------------------------+ |
  | |              Code maturity level options  --->                                            | |
  | |              General setup  --->                                                          | |
  | |              Loadable module support  --->                                                | |
  | |              Block layer  --->                                                            | |
  | |              System Type  --->                                                            | |
  | |              Bus support  --->                                                            | |
  | |              Kernel Features  --->                                                        | |
  | |              Boot options  --->                                                           | |
  | |              Floating point emulation  --->                                               | |
  | +----------v(+)-----------------------------------------------------------------------------+ |
  +-----------------------------------------------------------------------------------------------+
  |                               <Select>    < Exit >    < Help >                                |
  +-----------------------------------------------------------------------------------------------+

将S3C2410 LCD framebuffer support修改为M
-> Device Drivers
-> Graphics support
S3C2410 LCD framebuffer support

2.编译kernel

book@book-desktop:/work/system/linux-2.6.22.6$ make uImage

…
iis_probe' and 's3c2410iis_remove')
  Kernel: arch/arm/boot/Image is ready
  Kernel: arch/arm/boot/zImage is ready
  Image arch/arm/boot/uImage is ready

book@book-desktop:/work/system/linux-2.6.22.6$ cp arch/arm/boot/uImage /work/nfs_root/uImage_nolcd
book@book-desktop:/work/system/linux-2.6.22.6$ ls /work/nfs_root/uImage_nolcd -l
-rw-r--r-- 1 book book 1842388 2016-08-10 01:02 /work/nfs_root/uImage_nolcd

3.编译模块

book@book-desktop:/work/system/linux-2.6.22.6$ make modules

…
  Building modules, stage 2.
  MODPOST 26 modules

4.使用新uImage启动开发板

开发板reboot，进入uboot

# reboot
…

+---------------------------------------------+
| S3C2440A USB Downloader ver R0.03 2004 Jan  |
+---------------------------------------------+
USB: IN_ENDPOINT:1 OUT_ENDPOINT:3
FORMAT: <ADDR(DATA):4>+<SIZE(n+10):4>+<DATA:n>+<CS:2>
NOTE: Power off/on or press the reset button for 1 sec
      in order to get a valid USB device address.

Hit any key to stop autoboot:  0 

##### 100ask Bootloader for OpenJTAG #####
[n] Download u-boot to Nand Flash
[k] Download Linux kernel uImage
[j] Download root_jffs2 image
[y] Download root_yaffs image
[d] Download to SDRAM & Run
[z] Download zImage into RAM
[g] Boot linux from RAM
[f] Format the Nand Flash
[s] Set the boot parameters
[b] Boot the system
[r] Reboot u-boot
[q] Quit from menu
Enter your selection: q
OpenJTAG> 

查看开发板IP地址和服务器IP地址是否在同一网段

OpenJTAG> print
bootcmd=nand read.jffs2 0x30007FC0 kernel; bootm 0x30007FC0
bootdelay=2
baudrate=115200
ethaddr=08:00:3e:26:0a:5b
netmask=255.255.255.0
mtdids=nand0=nandflash0
mtdparts=mtdparts=nandflash0:256k@0(bootloader),128k(params),2m(kernel),-(root)
bootargs=noinitrd root=/dev/nfs nfsroot=192.168.10.175:/work/nfs_root/first_fs ip=192.168.10.11:192.168.10.175:192.168.10.1:255.255.255.0::eth0:off init=/linuxrc console=ttySAC0
ipaddr=192.168.10.11
serverip=192.168.10.101
stdin=serial
stdout=serial
stderr=serial
partition=nand0,0
mtddevnum=0
mtddevname=bootloader

Environment size: 556/131068 bytes

nfs下载新uImage

OpenJTAG> nfs 30000000 192.168.10.175:/work/nfs_root/uImage_nolcd
dm9000 i/o: 0x20000000, id: 0x90000a46 
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:5b
could not establish link
File transfer via NFS from server 192.168.10.175; our IP address is 192.168.10.11
Filename '/work/nfs_root/uImage_nolcd'.
Load address: 0x30000000
Loading: checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
checksum bad
#################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ###################################
done
Bytes transferred = 1842388 (1c1cd4 hex)

5.准备驱动程序

编译lcd.c

book@book-desktop:/work/my_drivers/10th_lcd$ make
…
book@book-desktop:/work/my_drivers/10th_lcd$ cp lcd.ko /work/nfs_root/first_fs
book@book-desktop:/work/my_drivers/10th_lcd$ ls -l /work/nfs_root/first_fs/lcd*
-rw-r--r-- 1 book book 79529 2016-08-10 01:21 /work/nfs_root/first_fs/lcd.ko

拷贝cfbcopyarea.ko,cfbfillrect.ko,cfbimgblt.ko

book@book-desktop:/work/system/linux-2.6.22.6$ cp drivers/video/cfb*.ko /work/nfs_root/first_fs
book@book-desktop:/work/system/linux-2.6.22.6$ ls -l /work/nfs_root/first_fs/cfb*.ko
-rw-r--r-- 1 book book 79735 2016-08-10 01:18 /work/nfs_root/first_fs/cfbcopyarea.ko
-rw-r--r-- 1 book book 79524 2016-08-10 01:18 /work/nfs_root/first_fs/cfbfillrect.ko
-rw-r--r-- 1 book book 78123 2016-08-10 01:18 /work/nfs_root/first_fs/cfbimgblt.ko

6.装载驱动

# insmod cfbcopyarea.ko 
# insmod cfbfillrect.ko 
# insmod cfbimgblt.ko 
# insmod lcd.ko

7.查看结果

# ls /dev/fb*
/dev/fb0  /dev/fb1
# cat lcd.ko > /dev/fb1

LCD屏幕出现花屏

4.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>

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_platette[16];

static inline u_int chan_to_field(u_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);

    pseudo_platette[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:665 */
    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->screen_size   = 240*324*16/8;
    s3c_lcd->pseudo_palette = pseudo_platette;
    //s3c_lcd->screen_base = ;

    /* 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;
    *gpdcon = 0xaaaaaaaa;

    *gpbcon &= ~(3);
    *gpbcon |= 1;
    *gpbdat &= ~1;

    *gpgcon |= (3<<8);

    /* 3.2 根据LCD手册设置LCD控制器，比如VCLK频率等 */
    lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));

    lcd_regs->lcdcon1 = (4<<8) | (3<<5) | (0x0c<<1);

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

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

    lcd_regs->lcdcon4 = 4;

    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);

    lcd_regs->lcdcon1 |= (1<<0); 
    lcd_regs->lcdcon5 |= (1<<3); 
    *gpbdat |= 1;

    /* 4.注册 */
    register_framebuffer(s3c_lcd);

    return 0;
}

static void lcd_exit(void)
{
    unregister_framebuffer(s3c_lcd);
    lcd_regs->lcdcon1 &= ~(1<<0);
    *gpbdat &= ~1;
    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");

5.参考资料

韦东山Linux第2期视频_深入写驱动/LCD驱动程序*
参考kernel文件Fbmem.c