framebuffer的驱动框架

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subsys_initcall(fbmem_init);

下面是驱动框架的初始函数两件事情：注册设备创建类

fbmem_init(void){    proc_create("fb", 0, NULL, &fb_proc_fops);     //使用proc系统    if (register_chrdev(FB_MAJOR,"fb",&fb_fops))    //注册设备        printk("unable to get major %d for fb devs\n", FB_MAJOR);    fb_class = class_create(THIS_MODULE, "graphics");  //创建类    if (IS_ERR(fb_class)) {        printk(KERN_WARNING "Unable to create fb class; errno = %ld\n", PTR_ERR(fb_class));        fb_class = NULL;    }    return 0;}

接下来是登记设备函数

int register_framebuffer(struct fb_info *fb_info){    int i;    struct fb_event event;    struct fb_videomode mode;    //移除冲突的buffer    remove_conflicting_framebuffers(fb_info->apertures,                     fb_info->fix.id,fb_is_primary_device(fb_info));        num_registered_fb++;    //获得被未注册的结点    for (i = 0 ; i < FB_MAX; i++)           if (!registered_fb[i])            break;    fb_info->node = i;    mutex_init(&fb_info->lock);    mutex_init(&fb_info->mm_lock);    //最重要的  设备与类进行挂钩        fb_info->dev = device_create(fb_class, fb_info->device,                     MKDEV(FB_MAJOR, i), NULL, "fb%d", i);        fb_init_device(fb_info);       //设备注册成功之后 进行初始化  主要是一些属性的配置    if (fb_info->pixmap.addr == NULL) {        fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);        if (fb_info->pixmap.addr) {            fb_info->pixmap.size = FBPIXMAPSIZE;            fb_info->pixmap.buf_align = 1;            fb_info->pixmap.scan_align = 1;            fb_info->pixmap.access_align = 32;            fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;        }    }       fb_info->pixmap.offset = 0;    if (!fb_info->pixmap.blit_x)        fb_info->pixmap.blit_x = ~(u32)0;    if (!fb_info->pixmap.blit_y)        fb_info->pixmap.blit_y = ~(u32)0;    if (!fb_info->modelist.prev || !fb_info->modelist.next)        INIT_LIST_HEAD(&fb_info->modelist);    fb_var_to_videomode(&mode, &fb_info->var);    fb_add_videomode(&mode, &fb_info->modelist);    registered_fb[i] = fb_info;    event.info = fb_info;    if (!lock_fb_info(fb_info))        return -ENODEV;    fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);    unlock_fb_info(fb_info);    return 0;}

这个文件函数大部分是一些软件配置，不涉及硬件，最重要的可能就是如下的函数了

fb_info->dev = device_create(fb_class, fb_info->device,                     MKDEV(FB_MAJOR, i), NULL, "fb%d", i);

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