QEMU学习（四）：LCD设备仿真及驱动开发

一.QEMU上创建LCD设备仿真

\qemu\hw\display\100ask_qemu_fb.c

1.在QEMU上创建LCD设备

static const TypeInfo ask100fb_info = {
    .name          = TYPE_100ASKFB,
    .parent        = TYPE_SYS_BUS_DEVICE,
    .instance_size = sizeof(ASK100FbState),  /* object_new_with_type 创建设备时会malloc该结构体, 并传给instance_init */ 
    .class_init    = ask100fb_class_init,
    .instance_init = ask100fb_init,          /* object_init_with_type */
    
};

void create_100ask_qemu_fb(void)
{
    DeviceState *dev;

    dev = qdev_create(NULL, TYPE_100ASKFB);
    qdev_init_nofail(dev);
}

static void ask100fb_register_types(void)
{
    type_register_static(&ask100fb_info);
}

type_init(ask100fb_register_types)

2.给LCD控制器提供回调函数

ask100fb_class_init设备类初始化实现图像更新，ask100fb_init设备实例初始化实现读写lcd驱动的值。

// 设备类初始化回调函数
static void ask100fb_class_init(ObjectClass *oc, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(oc);

    set_bit(DEVICE_CATEGORY_DISPLAY, dc->categories);
    dc->realize = ask100fb_realize;  /* ask100fb_realize 何时被调用 */

    /* Note: This device does not any state that we have to reset or migrate */
}

static void ask100fb_realize(DeviceState *dev, Error **errp)
{
    ASK100FbState *s = ASK100FB(dev);

	if (imx6ul_board_ui_backgroud_prepare())
		return;

    s->invalidate = 1;
	s->fb_xres = imx6ul_board_descs[selected_board].lcd.w;
	s->fb_yres = imx6ul_board_descs[selected_board].lcd.h;
	s->board_xres = board_mem_pixels.iWidth;
	s->board_yres = board_mem_pixels.iHeight;
	dev->id = "board";
    s->con = graphic_console_init(dev, 0, &ask100fb_ops, s); // 调用ops回调函数实现板子画面更新
    qemu_console_resize(s->con, s->board_xres, s->board_yres);

	s->input_state = qemu_input_handler_register(dev, &touchscreen_handler);
	qemu_input_handler_bind(s->input_state, dev->id, 0, NULL);
	qemu_input_handler_activate(s->input_state);
}

static const GraphicHwOps ask100fb_ops = {
    .invalidate  = ask100fb_invalidate,
    .gfx_update  = ask100fb_update,
};


static void ask100fb_update(void *opaque)
{
    ASK100FbState *s = ASK100FB(opaque);
    SysBusDevice *sbd;
    DisplaySurface *surface = qemu_console_surface(s->con);
	static int inited = 0;
	
    int dest_width;
    int src_width;
    int first = 0;
    int last  = 0;

	int fb_x, fb