gmidi.c

linux下面gadget设备驱动

	struct gmidi_device *dev = ep->driver_data;
	/* cable is ignored, because for now we only have one. */

	if (!dev->out_substream) {
		/* Nobody is listening - throw it on the floor. */
		return;
	}
	if (!test_bit(dev->out_substream->number, &dev->out_triggered)) {
		return;
	}
	snd_rawmidi_receive(dev->out_substream, data, length);
}

static void gmidi_handle_out_data(struct usb_ep *ep, struct usb_request *req)
{
	unsigned i;
	u8 *buf = req->buf;

	for (i = 0; i + 3 < req->actual; i += 4) {
		if (buf[i] != 0) {
			int cable = buf[i] >> 4;
			int length = gmidi_cin_length[buf[i] & 0x0f];
			gmidi_read_data(ep, cable, &buf[i + 1], length);
		}
	}
}

static void gmidi_complete(struct usb_ep *ep, struct usb_request *req)
{
	struct gmidi_device *dev = ep->driver_data;
	int status = req->status;

	switch (status) {
	case 0:				/* normal completion */
		if (ep == dev->out_ep) {
			/* we received stuff.
			   req is queued again, below */
			gmidi_handle_out_data(ep, req);
		} else if (ep == dev->in_ep) {
			/* our transmit completed.
			   see if there's more to go.
			   gmidi_transmit eats req, don't queue it again. */
			gmidi_transmit(dev, req);
			return;
		}
		break;

	/* this endpoint is normally active while we're configured */
	case -ECONNABORTED:		/* hardware forced ep reset */
	case -ECONNRESET:		/* request dequeued */
	case -ESHUTDOWN:		/* disconnect from host */
		VDBG(dev, "%s gone (%d), %d/%d\n", ep->name, status,
				req->actual, req->length);
		if (ep == dev->out_ep) {
			gmidi_handle_out_data(ep, req);
		}
		free_ep_req(ep, req);
		return;

	case -EOVERFLOW:		/* buffer overrun on read means that
					 * we didn't provide a big enough
					 * buffer.
					 */
	default:
		DBG(dev, "%s complete --> %d, %d/%d\n", ep->name,
				status, req->actual, req->length);
		break;
	case -EREMOTEIO:		/* short read */
		break;
	}

	status = usb_ep_queue(ep, req, GFP_ATOMIC);
	if (status) {
		ERROR(dev, "kill %s:  resubmit %d bytes --> %d\n",
				ep->name, req->length, status);
		usb_ep_set_halt(ep);
		/* FIXME recover later ... somehow */
	}
}

static int set_gmidi_config(struct gmidi_device *dev, gfp_t gfp_flags)
{
	int err = 0;
	struct usb_request *req;
	struct usb_ep *ep;
	unsigned i;

	err = usb_ep_enable(dev->in_ep, &bulk_in_desc);
	if (err) {
		ERROR(dev, "can't start %s: %d\n", dev->in_ep->name, err);
		goto fail;
	}
	dev->in_ep->driver_data = dev;

	err = usb_ep_enable(dev->out_ep, &bulk_out_desc);
	if (err) {
		ERROR(dev, "can't start %s: %d\n", dev->out_ep->name, err);
		goto fail;
	}
	dev->out_ep->driver_data = dev;

	/* allocate a bunch of read buffers and queue them all at once. */
	ep = dev->out_ep;
	for (i = 0; i < qlen && err == 0; i++) {
		req = alloc_ep_req(ep, buflen);
		if (req) {
			req->complete = gmidi_complete;
			err = usb_ep_queue(ep, req, GFP_ATOMIC);
			if (err) {
				DBG(dev, "%s queue req: %d\n", ep->name, err);
			}
		} else {
			err = -ENOMEM;
		}
	}
fail:
	/* caller is responsible for cleanup on error */
	return err;
}


static void gmidi_reset_config(struct gmidi_device *dev)
{
	if (dev->config == 0) {
		return;
	}

	DBG(dev, "reset config\n");

	/* just disable endpoints, forcing completion of pending i/o.
	 * all our completion handlers free their requests in this case.
	 */
	usb_ep_disable(dev->in_ep);
	usb_ep_disable(dev->out_ep);
	dev->config = 0;
}

/* change our operational config.  this code must agree with the code
 * that returns config descriptors, and altsetting code.
 *
 * it's also responsible for power management interactions. some
 * configurations might not work with our current power sources.
 *
 * note that some device controller hardware will constrain what this
 * code can do, perhaps by disallowing more than one configuration or
 * by limiting configuration choices (like the pxa2xx).
 */
static int
gmidi_set_config(struct gmidi_device *dev, unsigned number, gfp_t gfp_flags)
{
	int result = 0;
	struct usb_gadget *gadget = dev->gadget;

#if 0
	/* FIXME */
	/* Hacking this bit out fixes a bug where on receipt of two
	   USB_REQ_SET_CONFIGURATION messages, we end up with no
	   buffered OUT requests waiting for data. This is clearly
	   hiding a bug elsewhere, because if the config didn't
	   change then we really shouldn't do anything. */
	/* Having said that, when we do "change" from config 1
	   to config 1, we at least gmidi_reset_config() which
	   clears out any requests on endpoints, so it's not like
	   we leak or anything. */
	if (number == dev->config) {
		return 0;
	}
#endif

	if (gadget_is_sa1100(gadget) && dev->config) {
		/* tx fifo is full, but we can't clear it...*/
		ERROR(dev, "can't change configurations\n");
		return -ESPIPE;
	}
	gmidi_reset_config(dev);

	switch (number) {
	case GMIDI_CONFIG:
		result = set_gmidi_config(dev, gfp_flags);
		break;
	default:
		result = -EINVAL;
		/* FALL THROUGH */
	case 0:
		return result;
	}

	if (!result && (!dev->in_ep || !dev->out_ep)) {
		result = -ENODEV;
	}
	if (result) {
		gmidi_reset_config(dev);
	} else {
		char *speed;

		switch (gadget->speed) {
		case USB_SPEED_LOW:	speed = "low"; break;
		case USB_SPEED_FULL:	speed = "full"; break;
		case USB_SPEED_HIGH:	speed = "high"; break;
		default:		speed = "?"; break;
		}

		dev->config = number;
		INFO(dev, "%s speed\n", speed);
	}
	return result;
}


static void gmidi_setup_complete(struct usb_ep *ep, struct usb_request *req)
{
	if (req->status || req->actual != req->length) {
		DBG((struct gmidi_device *) ep->driver_data,
				"setup complete --> %d, %d/%d\n",
				req->status, req->actual, req->length);
	}
}

/*
 * The setup() callback implements all the ep0 functionality that's
 * not handled lower down, in hardware or the hardware driver (like
 * device and endpoint feature flags, and their status).  It's all
 * housekeeping for the gadget function we're implementing.  Most of
 * the work is in config-specific setup.
 */
static int gmidi_setup(struct usb_gadget *gadget,
			const struct usb_ctrlrequest *ctrl)
{
	struct gmidi_device *dev = get_gadget_data(gadget);
	struct usb_request *req = dev->req;
	int value = -EOPNOTSUPP;
	u16 w_index = le16_to_cpu(ctrl->wIndex);
	u16 w_value = le16_to_cpu(ctrl->wValue);
	u16 w_length = le16_to_cpu(ctrl->wLength);

	/* usually this stores reply data in the pre-allocated ep0 buffer,
	 * but config change events will reconfigure hardware.
	 */
	req->zero = 0;
	switch (ctrl->bRequest) {

	case USB_REQ_GET_DESCRIPTOR:
		if (ctrl->bRequestType != USB_DIR_IN) {
			goto unknown;
		}
		switch (w_value >> 8) {

		case USB_DT_DEVICE:
			value = min(w_length, (u16) sizeof(device_desc));
			memcpy(req->buf, &device_desc, value);
			break;
		case USB_DT_CONFIG:
			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:
			/* wIndex == language code.
			 * this driver only handles one language, you can
			 * add string tables for other languages, using
			 * any UTF-8 characters
			 */
			value = usb_gadget_get_string(&stringtab,
					w_value & 0xff, req->buf);
			if (value >= 0) {
				value = min(w_length, (u16)value);
			}
			break;
		}
		break;

	/* currently two configs, two speeds */
	case USB_REQ_SET_CONFIGURATION:
		if (ctrl->bRequestType != 0) {
			goto unknown;
		}
		if (gadget->a_hnp_support) {
			DBG(dev, "HNP available\n");
		} else if (gadget->a_alt_hnp_support) {
			DBG(dev, "HNP needs a different root port\n");
		} else {
			VDBG(dev, "HNP inactive\n");
		}
		spin_lock(&dev->lock);
		value = gmidi_set_config(dev, w_value, GFP_ATOMIC);
		spin_unlock(&dev->lock);
		break;
	case USB_REQ_GET_CONFIGURATION:
		if (ctrl->bRequestType != USB_DIR_IN) {
			goto unknown;
		}
		*(u8 *)req->buf = dev->config;
		value = min(w_length, (u16)1);
		break;

	/* until we add altsetting support, or other interfaces,
	 * only 0/0 are possible.  pxa2xx only supports 0/0 (poorly)
	 * and already killed pending endpoint I/O.
	 */
	case USB_REQ_SET_INTERFACE:
		if (ctrl->bRequestType != USB_RECIP_INTERFACE) {
			goto unknown;
		}
		spin_lock(&dev->lock);
		if (dev->config && w_index < GMIDI_NUM_INTERFACES
			&& w_value == 0)
		{
			u8 config = dev->config;

			/* resets interface configuration, forgets about
			 * previous transaction state (queued bufs, etc)
			 * and re-inits endpoint state (toggle etc)
			 * no response queued, just zero status == success.
			 * if we had more than one interface we couldn't
			 * use this "reset the config" shortcut.
			 */
			gmidi_reset_config(dev);
			gmidi_set_config(dev, config, GFP_ATOMIC);
			value = 0;
		}
		spin_unlock(&dev->lock);
		break;
	case USB_REQ_GET_INTERFACE:
		if (ctrl->bRequestType != (USB_DIR_IN|USB_RECIP_INTERFACE)) {
			goto unknown;
		}
		if (!dev->config) {
			break;
		}
		if (w_index >= GMIDI_NUM_INTERFACES) {
			value = -EDOM;
			break;
		}
		*(u8 *)req->buf = 0;
		value = min(w_length, (u16)1);
		break;

	default:
unknown:
		VDBG(dev, "unknown control req%02x.%02x v%04x i%04x l%d\n",
			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);
		if (value < 0) {
			DBG(dev, "ep_queue --> %d\n", value);
			req->status = 0;
			gmidi_setup_complete(gadget->ep0, req);
		}
	}

	/* device either stalls (value < 0) or reports success */
	return value;
}

static void gmidi_disconnect(struct usb_gadget *gadget)
{
	struct gmidi_device *dev = get_gadget_data(gadget);
	unsigned long flags;

	spin_lock_irqsave(&dev->lock, flags);
	gmidi_reset_config(dev);

	/* a more significant application might have some non-usb
	 * activities to quiesce here, saving resources like power
	 * or pushing the notification up a network stack.
	 */
	spin_unlock_irqrestore(&dev->lock, flags);

	/* next we may get setup() calls to enumerate new connections;
	 * or an unbind() during shutdown (including removing module).
	 */
}

static void /* __init_or_exit */ gmidi_unbind(struct usb_gadget *gadget)
{
	struct gmidi_device *dev = get_gadget_data(gadget);
	struct snd_card *card;

	DBG(dev, "unbind\n");

	card = dev->card;
	dev->card = NULL;
	if (card) {
		snd_card_free(card);
	}

	/* 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 gmidi_snd_free(struct snd_device *device)
{
	return 0;
}

static void gmidi_transmit_packet(struct usb_request *req, uint8_t p0,
					uint8_t p1, uint8_t p2, uint8_t p3)
{
	unsigned length = req->length;
	u8 *buf = (u8 *)req->buf + length;

	buf[0] = p0;
	buf[1] = p1;
	buf[2] = p2;
	buf[3] = p3;
	req->length = length + 4;
}

/*
 * Converts MIDI commands to USB MIDI packets.
 */
static void gmidi_transmit_byte(struct usb_request *req,
				struct gmidi_in_port *port, uint8_t b)
{
	uint8_t p0 = port->cable;

	if (b >= 0xf8) {
		gmidi_transmit_packet(req, p0 | 0x0f, b, 0, 0);
	} else if (b >= 0xf0) {
		switch (b) {
		case 0xf0:
			port->data[0] = b;
			port->state = STATE_SYSEX_1;
			break;