Android系統(tǒng)的開(kāi)機(jī)畫(huà)面顯示過(guò)程分析

/**  
 *      fbmem_init - init frame buffer subsystem  
 *  
 *      Initialize the frame buffer subsystem.  
 *  
 *      NOTE: This function is _only_ to be called by drivers/char/mem.c.  
 *  
 */   
   
static int __init   
fbmem_init(void)   
{   
        proc_create("fb", 0, NULL, &fb_proc_fops);   
   
        if (register_chrdev(FB_MAJOR,"fb",&fb_fops))   
                printk("unable to get major %d for fb devs\n", FB_MAJOR);   
   
        fb_class = class_create(THIS_MODULE, "graphics");   
        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;   
}   

EXPORT_SYMBOL(register_framebuffer);   

/**  
 *      register_framebuffer - registers a frame buffer device  
 *      @fb_info: frame buffer info structure  
 *  
 *      Registers a frame buffer device @fb_info.  
 *  
 *      Returns negative errno on error, or zero for success.  
 *  
 */   
   
int   
register_framebuffer(struct fb_info *fb_info)   
{   
        int i;   
        struct fb_event event;   
        ......   
   
        if (num_registered_fb == FB_MAX)   
                return -ENXIO;   
   
        ......   
   
        num_registered_fb++;   
        for (i = 0 ; i < FB_MAX; i++)   
                if (!registered_fb[i])   
                        break;   
        fb_info->node = i;   
        mutex_init(&fb_info->lock);   
        fb_info->dev = device_create(fb_class, fb_info->device,   
                                     MKDEV(FB_MAJOR, i), NULL, "fb%d", i);   
        if (IS_ERR(fb_info->dev)) {   
                /* Not fatal */   
                printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));   
                fb_info->dev = NULL;   
        } else   
                fb_init_device(fb_info);   
   
        ......   
   
        registered_fb[i] = fb_info;   
   
        event.info = fb_info;   
        fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);   
        return 0;   
}   

static struct notifier_block fbcon_event_notifier = {   
        .notifier_call  = fbcon_event_notify,   
};   
   
......   
   
static int __init fb_console_init(void)   
{   
        int i;   
   
        acquire_console_sem();   
        fb_register_client(&fbcon_event_notifier);   
        fbcon_device = device_create(fb_class, NULL, MKDEV(0, 0), NULL,   
                                     "fbcon");   
   
        if (IS_ERR(fbcon_device)) {   
                printk(KERN_WARNING "Unable to create device "   
                       "for fbcon; errno = %ld\n",   
                       PTR_ERR(fbcon_device));   
                fbcon_device = NULL;   
        } else   
                fbcon_init_device();   
   
        for (i = 0; i < MAX_NR_CONSOLES; i++)   
                con2fb_map[i] = -1;   
   
        release_console_sem();   
        fbcon_start();   
        return 0;   
}   

static int fbcon_event_notify(struct notifier_block *self,   
                              unsigned long action, void *data)   
{   
        struct fb_event *event = data;   
        struct fb_info *info = event->info;   
        ......   
        int ret = 0;   
   
        ......   
   
        switch(action) {   
        ......   
        case FB_EVENT_FB_REGISTERED:   
                ret = fbcon_fb_registered(info);   
                break;   
        ......   
   
        }   
   
done:   
        return ret;   
}   

static int fbcon_fb_registered(struct fb_info *info)   
{   
        int ret = 0, i, idx = info->node;   
   
        fbcon_select_primary(info);   
   
        if (info_idx == -1) {   
                for (i = first_fb_vc; i <= last_fb_vc; i++) {   
                        if (con2fb_map_boot[i] == idx) {   
                                info_idx = idx;   
                                break;   
                        }   
                }   
   
                if (info_idx != -1)   
                        ret = fbcon_takeover(1);   
        } else {   
                for (i = first_fb_vc; i <= last_fb_vc; i++) {   
                        if (con2fb_map_boot[i] == idx)   
                                set_con2fb_map(i, idx, 0);   
                }   
        }   
   
        return ret;   
}   

static int fbcon_takeover(int show_logo)   
{   
        int err, i;   
   
        if (!num_registered_fb)   
                return -ENODEV;   
   
        if (!show_logo)   
                logo_shown = FBCON_LOGO_DONTSHOW;   
   
        for (i = first_fb_vc; i <= last_fb_vc; i++)   
                con2fb_map[i] = info_idx;   
   
        err = take_over_console(&fb_con, first_fb_vc, last_fb_vc,   
                                fbcon_is_default);   
   
        if (err) {   
                for (i = first_fb_vc; i <= last_fb_vc; i++) {   
                        con2fb_map[i] = -1;   
                }   
                info_idx = -1;   
        }   
   
        return err;   
}   

/*  
 *  The console `switch' structure for the frame buffer based console  
 */   
   
static const struct consw fb_con = {   
        .owner                  = THIS_MODULE,   
        .con_startup            = fbcon_startup,   
        .con_init               = fbcon_init,   
        .con_deinit             = fbcon_deinit,   
        .con_clear              = fbcon_clear,   
        .con_putc               = fbcon_putc,   
        .con_putcs              = fbcon_putcs,   
        .con_cursor             = fbcon_cursor,   
        .con_scroll             = fbcon_scroll,   
        .con_bmove              = fbcon_bmove,   
        .con_switch             = fbcon_switch,   
        .con_blank              = fbcon_blank,   
        .con_font_set           = fbcon_set_font,   
        .con_font_get           = fbcon_get_font,   
        .con_font_default       = fbcon_set_def_font,   
        .con_font_copy          = fbcon_copy_font,   
        .con_set_palette        = fbcon_set_palette,   
        .con_scrolldelta        = fbcon_scrolldelta,   
        .con_set_origin         = fbcon_set_origin,   
        .con_invert_region      = fbcon_invert_region,   
        .con_screen_pos         = fbcon_screen_pos,   
        .con_getxy              = fbcon_getxy,   
        .con_resize             = fbcon_resize,   
};   

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