Linux USB gadget设备驱动解析(4)--编写一个gadget驱动
value = min(w_length, (u16) sizeof device_desc);
memcpy(req->buf, device_desc, value);
break;
case USB_DT_CONFIG: //获取配置,注意:会根据fs_loopback_function读取到接口、端点描述符,注意通过config_buf完成读取数据及数量的统计。
value = config_buf(gadget, req->buf,
w_value >> 8,
w_value 0xff);
if (value >= 0)
value = min(w_length, (u16) value);
break;
case USB_DT_STRING:
value = usb_gadget_get_string(stringtab,
w_value 0xff, req->buf);
if (value >= 0)
value = min(w_length, (u16) value);
break;
}
break;
case USB_REQ_SET_CONFIGURATION:
if (ctrl->bRequestType != 0)
goto unknown;
spin_lock(dev->lock);
value = zero_set_config(dev, w_value);//激活相应的端点
spin_unlock(dev->lock);
break;
default:
unknown:
printk(
unknown control req%02x.%02x v%04x i%04x l%dn,
ctrl->bRequestType, ctrl->bRequest,
w_value, w_index, w_length);
}
/* respond with data transfer before status phase */
if (value >= 0) {
req->length = value;
req->zero = value w_length;
value = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);//通过端点0完成setup
if (value 0) {
printk(ep_queue --> %dn, value);
req->status = 0;
zero_setup_complete(gadget->ep0, req);
}
}
/* device either stalls (value 0) or reports success */
return value;
}
static void zero_unbind(struct usb_gadget *gadget) //解除绑定
{
struct zero_dev *dev = get_gadget_data(gadget);
printk(unbindn);
unregister_chrdev_region (MKDEV (usb_zero_major, 0), 1);
cdev_del ((dev->cdev));
/* we've already been disconnected ... no i/o is active */
if (dev->req) {
dev->req->length = USB_BUFSIZ;
free_ep_req(gadget->ep0, dev->req);
}
kfree(dev);
set_gadget_data(gadget, NULL);
}
static int __init zero_bind(struct usb_gadget *gadget) //绑定过程
{
struct zero_dev *dev;
struct usb_ep *ep;
int gcnum;
usb_ep_autoconfig_reset(gadget);
ep = usb_ep_autoconfig(gadget, fs_sink_desc);//根据端点描述符及控制器端点情况,分配一个合适的端点。
if (!ep)
goto enomem;
EP_OUT_NAME = ep->name; //记录名称
gcnum = usb_gadget_controller_number(gadget);//获得控制器代号
if (gcnum >= 0)
device_desc.bcdDevice = cpu_to_le16(0x0200 + gcnum);//赋值设备描述符
else {
pr_warning(%s: controller '%s' not recognizedn,
shortname, gadget->name);
device_desc.bcdDevice = __constant_cpu_to_le16(0x9999);
}
dev = kzalloc(sizeof(*dev), GFP_KERNEL); //分配设备结构体
if (!dev)
return -ENOMEM;
spin_lock_init(dev->lock);
dev->gadget = gadget;
set_gadget_data(gadget, dev);
dev->req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);//分配一个请求
if (!dev->req)
goto enomem;
dev->req->buf = kmalloc(USB_BUFSIZ, GFP_KERNEL);
if (!dev->req->buf)
goto enomem;
dev->req->complete = zero_setup_complete;
dev->out_ep=ep; //记录端点(就是接收host端数据的端点)
printk(name=%sn,dev->out_ep->name); //打印出这个端点的名称
ep->driver_data=dev;
device_desc.bMaxPacketSize0 = gadget->ep0->maxpacket;
usb_gadget_set_selfpowered(gadget);
gadget->ep0->driver_data = dev;
snprintf(manufacturer, sizeof manufacturer, %s %s with %s,
init_utsname()->sysname, init_utsname()->release,
gadget->name);
/**************************字符设备注册*******************/
dev_t usb_zero_dev = MKDEV (usb_zero_major, 0);
int result = register_chrdev_region (usb_zero_dev, 1, usb_zero);
if (result 0)
{
printk (KERN_NOTICE Unable to get usb_transfer region, error %dn,result);
return 0;
}
usb_zero_setup_cdev (dev, 0);
return 0;
enomem:
zero_unbind(gadget);
return -ENOMEM;
}
/*-------------------------------------------------------------------------*/
static struct usb_gadget_driver zero_driver = { //gadget驱动的核心数据结构
#ifdef CONFIG_USB_GADGET_DUALSPEED
.speed = USB_SPEED_HIGH,
#else
.speed = USB_SPEED_FULL,
#endif
.function = (char *) longname,
.bind = zero_bind,
.unbind = __exit_p(zero_unbind),
.setup = zero_setup,
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