LCD驱动程序

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我是靠谱客的博主仁爱鸡翅，这篇文章主要介绍LCD驱动程序，现在分享给大家，希望可以做个参考。

学习目标：熟悉TFT LCD的概念，分层驱动工作原理和程序编写。

一、LCD 概念

1. 显示器数据组织格式

1）一幅图像成为一帧，每帧由多行组成，每行由多个像素组成。每个像素的颜色由若干位表示，对于256色LCD，每个像素由8位表示，称为8BPP。

2）显示器呈Z字行的路线进行扫描显示，使用HSYNC、VSYNC控制扫描和跳转的路径；

2、操作过程

1）设置LCD的HSYNC、VSYNCVCLK等信号的参数，并将帧内存的地址告诉LCD控制器，塔克自动的发起DMA传输，从帧内存中得到图像数据，出现在数据总线VD[23:0]上。我们只需要将显示的图像数据写入帧内存中即可。

2）图像数据的存储：

例如：由三原色组建的256色（8BPP）显示模式，使用8位数据表示一个像素的颜色。但特殊的是，这8位数据用于表示在调色板中的索引值。这里的调色板使用256*16的内存，即使用16BPP的显示格式来表示对应各个索引值的颜色。因此，最终在LCD显示的仍为16BPP的数据。

内存数据和像素对应的关系为：

其中，P1、P2...为一个个的像素。

像素在调色板中的数据存放模式16BPP分为两种格式：5：6：5和5：5：5：1.即：

二、LCD驱动

1、帧缓冲设备

frambuffer设备层是对显示设备的一种抽象。其中，帧缓冲是Linux为显示设备提供的一个接口，它把一些显示设备描述成一个缓冲区，允许应用程序通过FrameBuffer定义好的接口访问这些图形设备，从而不用去关心具体的硬件细节。对于帧缓冲设备而言，只要在显示缓冲区与显示点对应的区域写入颜色值，对应的颜色就会自动的在屏幕上显示。

2、LCD作为一种帧缓冲设备，也是一种标准的字符型设备，对应于文件系统下/dev/fb%d设备文件。

3、驱动结构

首先分析一下driver/video/fbmem.c

1）进入__init fbmem_init（入口函数），主要创建了字符设备“fb”和类，利用cat 命令查看（cat /proc/devices）,可看到该目录下的fb，主设备号为29。由于还没有注册LCD驱动，所以没有设备节点，

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 1 static int __init fbmem_init(void)
 2 {
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create_proc_read_entry("fb", 0, NULL, fbmem_read_proc, NULL);
 4
//创建字符设备"fb"
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if (register_chrdev(FB_MAJOR,"fb",&fb_fops))
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printk("unable to get major %d for fb devsn", FB_MAJOR);
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fb_class = class_create(THIS_MODULE, "graphics"); //创建类graphics"
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if (IS_ERR(fb_class)) {
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printk(KERN_WARNING "Unable to create fb class; errno = %ldn", PTR_ERR(fb_class));
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fb_class = NULL;
12 
}
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return 0;
14 }

2）fb_fops结构体及open函数

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 1 static const struct file_operations fb_fops = {
 2
.owner =
THIS_MODULE,
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.read
=
fb_read,
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.write =
fb_write,
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.ioctl =
fb_ioctl,
 6 #ifdef CONFIG_COMPAT
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.compat_ioctl = fb_compat_ioctl,
 8 #endif
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.mmap =
fb_mmap,
10
.open =
fb_open,
11
.release =
fb_release,
12 #ifdef HAVE_ARCH_FB_UNMAPPED_AREA
13
.get_unmapped_area = get_fb_unmapped_area,
14 #endif
15 #ifdef CONFIG_FB_DEFERRED_IO
16
.fsync =
fb_deferred_io_fsync,
17 #endif
18 };

-->fb_open函数:

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 1 static int fb_open(struct inode *inode, struct file *file)
 2 {
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int fbidx = iminor(inode); //取出设备次设备号
 4
struct fb_info *info;
//定义一个fb_info结构体
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int res = 0;
 6
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if (fbidx >= FB_MAX)
 8
return -ENODEV;
 9 #ifdef CONFIG_KMOD
10
if (!(info = registered_fb[fbidx])) // 在次设备里面得到fb_info结构信息(lcd的驱动信息)赋值给info

11 
try_to_load(fbidx);
12 #endif /* CONFIG_KMOD */
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if (!(info = registered_fb[fbidx]))
14
return -ENODEV;
15
if (!try_module_get(info->fbops->owner))
16
return -ENODEV;
17
file->private_data = info;
18
if (info->fbops->fb_open) {
//如果该设备info结构体有open函数，就执行registered_fb[fbidx]->fbops->fb_open

19
res = info->fbops->fb_open(info,1);
20
if (res)
21
module_put(info->fbops->owner);
22 
}
23
return res;
24 }

由于fb设备(帧缓冲设备)主设备号固定，不同设备以次设备号进行区分，执行该设备open函数时，最终指向的是对应设备的open函数。

接下来看一下fb_read函数：

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1 static ssize_t
 2 fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 3 {
 4
unsigned long p = *ppos;
 5
struct inode *inode = file->f_path.dentry->d_inode;
 6
int fbidx = iminor(inode);

//取出设备次设备号
 7
struct fb_info *info = registered_fb[fbidx];
//定义并获取设备的fb_info结构体
 8
u32 *buffer, *dst;
 9
u32 __iomem *src;
10
int c, i, cnt = 0, err = 0;
11
unsigned long total_size;
12
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if (!info || ! info->screen_base)
14
return -ENODEV;
15
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if (info->state != FBINFO_STATE_RUNNING)
17
return -EPERM;
18
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if (info->fbops->fb_read)
20
return info->fbops->fb_read(info, buf, count, ppos); //如果该设备fb_info结构体有read函数，就执行registered_fb[fbidx]->fbops->fb_read
21
22
total_size = info->screen_size;
23
24
if (total_size == 0)
25
total_size = info->fix.smem_len;
26
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if (p >= total_size)
28
return 0;
29
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if (count >= total_size)
31
count = total_size;
32
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if (count + p > total_size)
34
count = total_size - p;
35
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buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
37 
GFP_KERNEL);
38
if (!buffer)
39
return -ENOMEM;
40
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src = (u32 __iomem *) (info->screen_base + p);
42
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if (info->fbops->fb_sync)
44
info->fbops->fb_sync(info);
45
46
while (count) {
47
c
= (count > PAGE_SIZE) ? PAGE_SIZE : count;
48
dst = buffer;
49
for (i = c >> 2; i--; )
50
*dst++ = fb_readl(src++);
51
if (c & 3) {
52
u8 *dst8 = (u8 *) dst;
53
u8 __iomem *src8 = (u8 __iomem *) src;
54
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for (i = c & 3; i--;)
56
*dst8++ = fb_readb(src8++);
57
58
src = (u32 __iomem *) src8;
59 
}
60
61
if (copy_to_user(buf, buffer, c)) {
62
err = -EFAULT;
63
break;
64 
}
65
*ppos += c;
66
buf += c;
67
cnt += c;
68
count -= c;
69 
}
71 
kfree(buffer);
73
return (err) ? err : cnt;
74 }

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 1 static ssize_t
 2 fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 3 {
 4
unsigned long p = *ppos;
 5
struct inode *inode = file->f_path.dentry->d_inode;
 6
int fbidx = iminor(inode);

 //取出设备次设备号
 7
struct fb_info *info = registered_fb[fbidx];
//定义并获取设备的fb_info结构体
 8
u32 *buffer, *dst;
 9
u32 __iomem *src;
10
int c, i, cnt = 0, err = 0;
11
unsigned long total_size;
12
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if (!info || ! info->screen_base)
14
return -ENODEV;
15
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if (info->state != FBINFO_STATE_RUNNING)
17
return -EPERM;
18
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if (info->fbops->fb_read)
20
return info->fbops->fb_read(info, buf, count, ppos); //如果该设备fb_info结构体有read函数，就执行registered_fb[fbidx]->fbops->fb_read
21
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total_size = info->screen_size;
23
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if (total_size == 0)
25
total_size = info->fix.smem_len;
26
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if (p >= total_size)
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return 0;
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if (count >= total_size)
31
count = total_size;
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if (count + p > total_size)
34
count = total_size - p;
35
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buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
37 
GFP_KERNEL);
38
if (!buffer)
39
return -ENOMEM;
40
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src = (u32 __iomem *) (info->screen_base + p);
42
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if (info->fbops->fb_sync)
44
info->fbops->fb_sync(info);
45
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while (count) {
47
c
= (count > PAGE_SIZE) ? PAGE_SIZE : count;
48
dst = buffer;
49
for (i = c >> 2; i--; )
50
*dst++ = fb_readl(src++);
51
if (c & 3) {
52
u8 *dst8 = (u8 *) dst;
53
u8 __iomem *src8 = (u8 __iomem *) src;
54
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for (i = c & 3; i--;)
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*dst8++ = fb_readb(src8++);
57
58
src = (u32 __iomem *) src8;
59 
}
60
61
if (copy_to_user(buf, buffer, c)) {
62
err = -EFAULT;
63
break;
64 
}
65
*ppos += c;
66
buf += c;
67
cnt += c;
68
count -= c;
69 
}
71 
kfree(buffer);
73
return (err) ? err : cnt;
74 }

由以上程序可知，read的调用和open类似。都依赖于对应设备的fb_info结构体info，在程序中是由registered_fb[fbidx]数组获取的。
3）最后，看一下registered_fb[fbidx]数组的定义，位于register_framebuffer函数中。

复制代码

1 int register_framebuffer(struct fb_info *fb_info)
 2 {
 3
int i;
 4
struct fb_event event;
 5
struct fb_videomode mode;
 6
 7
if (num_registered_fb == FB_MAX)
 8
return -ENXIO;
 9
num_registered_fb++;
10
for (i = 0 ; i < FB_MAX; i++)
11
if (!registered_fb[i])
12
break;
13
fb_info->node = i;
14
15
fb_info->dev = device_create(fb_class, fb_info->device,MKDEV(FB_MAJOR, i), "fb%d", i);//创建设备节点，名称为fbi，主设备号为FB_MAJOR 29，次设备号为i
17
if (IS_ERR(fb_info->dev)) {
18
/* Not fatal */
19
printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ldn", i, PTR_ERR(fb_info->dev));
20
fb_info->dev = NULL;
21
} else
22 
fb_init_device(fb_info);
23
24
if (fb_info->pixmap.addr == NULL) {
25
fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);
26
if (fb_info->pixmap.addr) {
27
fb_info->pixmap.size = FBPIXMAPSIZE;
28
fb_info->pixmap.buf_align = 1;
29
fb_info->pixmap.scan_align = 1;
30
fb_info->pixmap.access_align = 32;
31
fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;
32 
}
33 
}
34
fb_info->pixmap.offset = 0;
35
36
if (!fb_info->pixmap.blit_x)
37
fb_info->pixmap.blit_x = ~(u32)0;
38
39
if (!fb_info->pixmap.blit_y)
40
fb_info->pixmap.blit_y = ~(u32)0;
41
42
if (!fb_info->modelist.prev || !fb_info->modelist.next)
43
INIT_LIST_HEAD(&fb_info->modelist);
44
45
fb_var_to_videomode(&mode, &fb_info->var);
46
fb_add_videomode(&mode, &fb_info->modelist);
47
 registered_fb[i] = fb_info; //赋值到registered_fb[i]数组中
48
49
event.info = fb_info;
50
fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
51
return 0;
52 }

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 1 int register_framebuffer(struct fb_info *fb_info)
 2 {
 3
int i;
 4
struct fb_event event;
 5
struct fb_videomode mode;
 6
 7
if (num_registered_fb == FB_MAX)
 8
return -ENXIO;
 9
num_registered_fb++;
10
for (i = 0 ; i < FB_MAX; i++)
11
if (!registered_fb[i])
12
break;
13
fb_info->node = i;
14
15
fb_info->dev = device_create(fb_class, fb_info->device,MKDEV(FB_MAJOR, i), "fb%d", i);//创建设备节点，名称为fbi，主设备号为FB_MAJOR 29，次设备号为i
17
if (IS_ERR(fb_info->dev)) {
18
/* Not fatal */
19
printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ldn", i, PTR_ERR(fb_info->dev));
20
fb_info->dev = NULL;
21
} else
22 
fb_init_device(fb_info);
23
24
if (fb_info->pixmap.addr == NULL) {
25
fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);
26
if (fb_info->pixmap.addr) {
27
fb_info->pixmap.size = FBPIXMAPSIZE;
28
fb_info->pixmap.buf_align = 1;
29
fb_info->pixmap.scan_align = 1;
30
fb_info->pixmap.access_align = 32;
31
fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;
32 
}
33 
}
34
fb_info->pixmap.offset = 0;
35
36
if (!fb_info->pixmap.blit_x)
37
fb_info->pixmap.blit_x = ~(u32)0;
38
39
if (!fb_info->pixmap.blit_y)
40
fb_info->pixmap.blit_y = ~(u32)0;
41
42
if (!fb_info->modelist.prev || !fb_info->modelist.next)
43
INIT_LIST_HEAD(&fb_info->modelist);
44
45
fb_var_to_videomode(&mode, &fb_info->var);
46
fb_add_videomode(&mode, &fb_info->modelist);
47
 registered_fb[i] = fb_info; //赋值到registered_fb[i]数组中
48
49
event.info = fb_info;
50
fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
51
return 0;
52 }

接下来看一下fb硬件驱动程序，以/drivers/video/s3c2410fb.c为例。

1）驱动入口

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 1 static struct platform_driver s3c2410fb_driver = {
 2
.probe
= s3c2410fb_probe,
 3
.remove
= s3c2410fb_remove,
 4
.suspend
= s3c2410fb_suspend,
 5
.resume
= s3c2410fb_resume,
 6
.driver
= {
 7
.name
= "s3c2410-lcd",
 8
.owner
= THIS_MODULE,
 9 
},
10 };
11
12 int __devinit s3c2410fb_init(void)
13 {
14
return platform_driver_register(&s3c2410fb_driver);
15 }
16
17 static void __exit s3c2410fb_cleanup(void)
18 {
19
platform_driver_unregister(&s3c2410fb_driver);
20 }

2）当平台设备的驱动和设备匹配后，会直接调用prob函数。

复制代码

1 static int __init s3c2410fb_probe(struct platform_device *pdev)

2 {

3
struct s3c2410fb_info *info;

4
struct fb_info
*fbinfo;

5
struct s3c2410fb_hw *mregs;

6
int ret;

7
int irq;

8
int i;

9 
u32 lcdcon1;
 10
 11
mach_info = pdev->dev.platform_data;
//获取lcd设备信息
 12
if (mach_info == NULL) {
 13
dev_err(&pdev->dev,"no platform data for lcd, cannot attachn");
 14
return -EINVAL;
 15 
}
 25
fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev); //分配fb_info结构体
 26
if (!fbinfo) {
 27
return -ENOMEM;
 28 
}　　　　　//设置fb_info结构体 31
info = fbinfo->par;
 32
info->fb = fbinfo;
 33
info->dev = &pdev->dev;
 34
 35 
platform_set_drvdata(pdev, fbinfo);
 37
dprintk("devinitn");
 39
strcpy(fbinfo->fix.id, driver_name);
 41
memcpy(&info->regs, &mach_info->regs, sizeof(info->regs));
 43
/* Stop the video and unset ENVID if set */
 44
info->regs.lcdcon1 &= ~S3C2410_LCDCON1_ENVID;
 45
lcdcon1 = readl(S3C2410_LCDCON1);
 46
writel(lcdcon1 & ~S3C2410_LCDCON1_ENVID, S3C2410_LCDCON1);
 47
 48
info->mach_info
= pdev->dev.platform_data;
 49
 50
fbinfo->fix.type
= FB_TYPE_PACKED_PIXELS;
 51
fbinfo->fix.type_aux
= 0;
 52
fbinfo->fix.xpanstep
= 0;
 53
fbinfo->fix.ypanstep
= 0;
 54
fbinfo->fix.ywrapstep
= 0;
 55
fbinfo->fix.accel
= FB_ACCEL_NONE;
 64
fbinfo->fbops
= &s3c2410fb_ops;
 65
fbinfo->flags
= FBINFO_FLAG_DEFAULT;
 66
fbinfo->pseudo_palette
= &info->pseudo_pal;
 67  73
 74
fbinfo->var.upper_margin
= S3C2410_LCDCON2_GET_VBPD(mregs->lcdcon2) + 1;
 75
fbinfo->var.lower_margin
= S3C2410_LCDCON2_GET_VFPD(mregs->lcdcon2) + 1;
 76
fbinfo->var.vsync_len
= S3C2410_LCDCON2_GET_VSPW(mregs->lcdcon2) + 1;
 77
 78
fbinfo->var.left_margin
= S3C2410_LCDCON3_GET_HFPD(mregs->lcdcon3) + 1;
 79
fbinfo->var.right_margin
= S3C2410_LCDCON3_GET_HBPD(mregs->lcdcon3) + 1;
 80
fbinfo->var.hsync_len
= S3C2410_LCDCON4_GET_HSPW(mregs->lcdcon4) + 1;
 81  90
fbinfo->fix.smem_len
=
mach_info->xres.max *
 91
mach_info->yres.max *
 92
mach_info->bpp.max / 8;
 93
 94
for (i = 0; i < 256; i++)
 95
info->palette_buffer[i] = PALETTE_BUFF_CLEAR;
 96
 97
if (!request_mem_region((unsigned long)S3C24XX_VA_LCD, SZ_1M, "s3c2410-lcd")) {
 98
ret = -EBUSY;
 99
goto dealloc_fb;
100 
}
103
dprintk("got LCD regionn");
104
 //硬件相关的操作，中断、时钟....
105
ret = request_irq(irq, s3c2410fb_irq, IRQF_DISABLED, pdev->name, info);
106
if (ret) {
107
dev_err(&pdev->dev, "cannot get irq %d - err %dn", irq, ret);
108
ret = -EBUSY;
109
goto release_mem;
110 
}
111
112
info->clk = clk_get(NULL, "lcd");
113
if (!info->clk || IS_ERR(info->clk)) {
114
printk(KERN_ERR "failed to get lcd clock sourcen");
115
ret = -ENOENT;
116
goto release_irq;
117 
}
118
119
clk_enable(info->clk);
120
dprintk("got and enabled clockn");
121
122
msleep(1);
123
124
/* Initialize video memory */
125
ret = s3c2410fb_map_video_memory(info);
126
if (ret) {
127
printk( KERN_ERR "Failed to allocate video RAM: %dn", ret);
128
ret = -ENOMEM;
129
goto release_clock;
130 
}
137
ret = register_framebuffer(fbinfo);//注册fb_info结构体
138
if (ret < 0) {
139
printk(KERN_ERR "Failed to register framebuffer device: %dn", ret);
140
goto free_video_memory;
141 
}
142
143
/* create device files */
144
device_create_file(&pdev->dev, &dev_attr_debug);
145
146
printk(KERN_INFO "fb%d: %s frame buffer devicen",
147
fbinfo->node, fbinfo->fix.id);
148
149
return 0;
150
151 free_video_memory:
152 
s3c2410fb_unmap_video_memory(info);
153 release_clock:
154
clk_disable(info->clk);
155
clk_put(info->clk);
156 release_irq:
157 
free_irq(irq,info);
158 release_mem:
159
release_mem_region((unsigned long)S3C24XX_VA_LCD, S3C24XX_SZ_LCD);
160 dealloc_fb:
161 
framebuffer_release(fbinfo);
162
return ret;
163 }

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1 static int __init s3c2410fb_probe(struct platform_device *pdev)

2 {

3
struct s3c2410fb_info *info;

4
struct fb_info
*fbinfo;

5
struct s3c2410fb_hw *mregs;

6
int ret;

7
int irq;

8
int i;

9 
u32 lcdcon1;
 10
 11
mach_info = pdev->dev.platform_data;
//获取lcd设备信息
 12
if (mach_info == NULL) {
 13
dev_err(&pdev->dev,"no platform data for lcd, cannot attachn");
 14
return -EINVAL;
 15 
}
 25
fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev); //分配fb_info结构体
 26
if (!fbinfo) {
 27
return -ENOMEM;
 28 
}
　　　　　//设置fb_info结构体
 31
info = fbinfo->par;
 32
info->fb = fbinfo;
 33
info->dev = &pdev->dev;
 34
 35 
platform_set_drvdata(pdev, fbinfo);
 37
dprintk("devinitn");
 39
strcpy(fbinfo->fix.id, driver_name);
 41
memcpy(&info->regs, &mach_info->regs, sizeof(info->regs));
 43
/* Stop the video and unset ENVID if set */
 44
info->regs.lcdcon1 &= ~S3C2410_LCDCON1_ENVID;
 45
lcdcon1 = readl(S3C2410_LCDCON1);
 46
writel(lcdcon1 & ~S3C2410_LCDCON1_ENVID, S3C2410_LCDCON1);
 47
 48
info->mach_info
= pdev->dev.platform_data;
 49
 50
fbinfo->fix.type
= FB_TYPE_PACKED_PIXELS;
 51
fbinfo->fix.type_aux
= 0;
 52
fbinfo->fix.xpanstep
= 0;
 53
fbinfo->fix.ypanstep
= 0;
 54
fbinfo->fix.ywrapstep
= 0;
 55
fbinfo->fix.accel
= FB_ACCEL_NONE;

 64
fbinfo->fbops
= &s3c2410fb_ops;
 65
fbinfo->flags
= FBINFO_FLAG_DEFAULT;
 66
fbinfo->pseudo_palette
= &info->pseudo_pal;
 67  73
 74
fbinfo->var.upper_margin
= S3C2410_LCDCON2_GET_VBPD(mregs->lcdcon2) + 1;
 75
fbinfo->var.lower_margin
= S3C2410_LCDCON2_GET_VFPD(mregs->lcdcon2) + 1;
 76
fbinfo->var.vsync_len
= S3C2410_LCDCON2_GET_VSPW(mregs->lcdcon2) + 1;
 77
 78
fbinfo->var.left_margin
= S3C2410_LCDCON3_GET_HFPD(mregs->lcdcon3) + 1;
 79
fbinfo->var.right_margin
= S3C2410_LCDCON3_GET_HBPD(mregs->lcdcon3) + 1;
 80
fbinfo->var.hsync_len
= S3C2410_LCDCON4_GET_HSPW(mregs->lcdcon4) + 1;
 81  90
fbinfo->fix.smem_len
=
mach_info->xres.max *
 91
mach_info->yres.max *
 92
mach_info->bpp.max / 8;
 93
 94
for (i = 0; i < 256; i++)
 95
info->palette_buffer[i] = PALETTE_BUFF_CLEAR;
 96
 97
if (!request_mem_region((unsigned long)S3C24XX_VA_LCD, SZ_1M, "s3c2410-lcd")) {
 98
ret = -EBUSY;
 99
goto dealloc_fb;
100 
}
103
dprintk("got LCD regionn");
104
 //硬件相关的操作，中断、时钟....
105
ret = request_irq(irq, s3c2410fb_irq, IRQF_DISABLED, pdev->name, info);
106
if (ret) {
107
dev_err(&pdev->dev, "cannot get irq %d - err %dn", irq, ret);
108
ret = -EBUSY;
109
goto release_mem;
110 
}
111
112
info->clk = clk_get(NULL, "lcd");
113
if (!info->clk || IS_ERR(info->clk)) {
114
printk(KERN_ERR "failed to get lcd clock sourcen");
115
ret = -ENOENT;
116
goto release_irq;
117 
}
118
119
clk_enable(info->clk);
120
dprintk("got and enabled clockn");
121
122
msleep(1);
123
124
/* Initialize video memory */
125
ret = s3c2410fb_map_video_memory(info);
126
if (ret) {
127
printk( KERN_ERR "Failed to allocate video RAM: %dn", ret);
128
ret = -ENOMEM;
129
goto release_clock;
130 
}
137
ret = register_framebuffer(fbinfo);//注册fb_info结构体
138
if (ret < 0) {
139
printk(KERN_ERR "Failed to register framebuffer device: %dn", ret);
140
goto free_video_memory;
141 
}
142
143
/* create device files */
144
device_create_file(&pdev->dev, &dev_attr_debug);
145
146
printk(KERN_INFO "fb%d: %s frame buffer devicen",
147
fbinfo->node, fbinfo->fix.id);
148
149
return 0;
150
151 free_video_memory:
152 
s3c2410fb_unmap_video_memory(info);
153 release_clock:
154
clk_disable(info->clk);
155
clk_put(info->clk);
156 release_irq:
157 
free_irq(irq,info);
158 release_mem:
159
release_mem_region((unsigned long)S3C24XX_VA_LCD, S3C24XX_SZ_LCD);
160 dealloc_fb:
161 
framebuffer_release(fbinfo);
162
return ret;
163 }