musb_gadget.c

		/* set twice in case of double buffering */
		musb_writew(regs, MUSB_TXCSR, csr);
		/* REVISIT may be inappropriate w/o FIFONOTEMPTY ... */
		musb_writew(regs, MUSB_TXCSR, csr);

	} else {
		u16 int_rxe = musb_readw(mbase, MUSB_INTRRXE);

		if (hw_ep->is_shared_fifo)
			musb_ep->is_in = 0;
		if (musb_ep->is_in)
			goto fail;

		if (tmp > hw_ep->max_packet_sz_rx) {
			DBG(4, "%s: packet size beyond hw fifo size\n", __func__);
			goto fail;
		}

		int_rxe |= (1 << epnum);
		musb_writew(mbase, MUSB_INTRRXE, int_rxe);

		/* REVISIT if can_bulk_combine() use by updating "tmp"
		 * likewise high bandwidth periodic rx
		 */
		/* Set RXMAXP with the FIFO size of the endpoint
		 * to disable double buffering mode.
		 */
		musb_writew(regs, MUSB_RXMAXP, musb_ep->packet_sz | (musb_ep->hb_mult << 11));

		/* force shared fifo to OUT-only mode */
		if (hw_ep->is_shared_fifo) {
			csr = musb_readw(regs, MUSB_TXCSR);
			csr &= ~(MUSB_TXCSR_MODE | MUSB_TXCSR_TXPKTRDY);
			musb_writew(regs, MUSB_TXCSR, csr);
		}

		csr = MUSB_RXCSR_FLUSHFIFO | MUSB_RXCSR_CLRDATATOG;
		if (musb_ep->type == USB_ENDPOINT_XFER_ISOC)
			csr |= MUSB_RXCSR_P_ISO;
		else if (musb_ep->type == USB_ENDPOINT_XFER_INT)
			csr |= MUSB_RXCSR_DISNYET;

		/* set twice in case of double buffering */
		musb_writew(regs, MUSB_RXCSR, csr);
		musb_writew(regs, MUSB_RXCSR, csr);
	}

	/* NOTE:  all the I/O code _should_ work fine without DMA, in case
	 * for some reason you run out of channels here.
	 */
	if (is_dma_capable() && musb->dma_controller) {
		struct dma_controller	*c = musb->dma_controller;

		musb_ep->dma = c->channel_alloc(c, hw_ep,
				(desc->bEndpointAddress & USB_DIR_IN));
	} else
		musb_ep->dma = NULL;

	musb_ep->desc = desc;
	musb_ep->busy = 0;
	musb_ep->wedged = 0;
	status = 0;

	pr_debug("%s periph: enabled %s for %s %s, %smaxpacket %d\n",
			musb_driver_name, musb_ep->end_point.name,
			({ char *s; switch (musb_ep->type) {
			case USB_ENDPOINT_XFER_BULK:	s = "bulk"; break;
			case USB_ENDPOINT_XFER_INT:	s = "int"; break;
			default:			s = "iso"; break;
			}; s; }),
			musb_ep->is_in ? "IN" : "OUT",
			musb_ep->dma ? "dma, " : "",
			musb_ep->packet_sz);

	schedule_work(&musb->irq_work);

fail:
	spin_unlock_irqrestore(&musb->lock, flags);
	return status;
}

/*
 * Disable an endpoint flushing all requests queued.
 */
static int musb_gadget_disable(struct usb_ep *ep)
{
	unsigned long	flags;
	struct musb	*musb;
	u8		epnum;
	struct musb_ep	*musb_ep;
	void __iomem	*epio;
	int		status = 0;

	musb_ep = to_musb_ep(ep);
	musb = musb_ep->musb;
	epnum = musb_ep->current_epnum;
	epio = musb->endpoints[epnum].regs;

	spin_lock_irqsave(&musb->lock, flags);
	musb_ep_select(musb->mregs, epnum);

	/* zero the endpoint sizes */
	if (musb_ep->is_in) {
		u16 int_txe = musb_readw(musb->mregs, MUSB_INTRTXE);
		int_txe &= ~(1 << epnum);
		musb_writew(musb->mregs, MUSB_INTRTXE, int_txe);
		musb_writew(epio, MUSB_TXMAXP, 0);
	} else {
		u16 int_rxe = musb_readw(musb->mregs, MUSB_INTRRXE);
		int_rxe &= ~(1 << epnum);
		musb_writew(musb->mregs, MUSB_INTRRXE, int_rxe);
		musb_writew(epio, MUSB_RXMAXP, 0);
	}

	musb_ep->desc = NULL;

	/* abort all pending DMA and requests */
	nuke(musb_ep, -ESHUTDOWN);

	schedule_work(&musb->irq_work);

	spin_unlock_irqrestore(&(musb->lock), flags);

	DBG(2, "%s\n", musb_ep->end_point.name);

	return status;
}

/*
 * Allocate a request for an endpoint.
 * Reused by ep0 code.
 */
struct usb_request *musb_alloc_request(struct usb_ep *ep, gfp_t gfp_flags)
{
	struct musb_ep		*musb_ep = to_musb_ep(ep);
	struct musb_request	*request = NULL;

	request = kzalloc(sizeof *request, gfp_flags);
	if (!request) {
		DBG(4, "not enough memory\n");
		return NULL;
	}

	INIT_LIST_HEAD(&request->request.list);
	request->request.dma = DMA_ADDR_INVALID;
	request->epnum = musb_ep->current_epnum;
	request->ep = musb_ep;

	return &request->request;
}

/*
 * Free a request
 * Reused by ep0 code.
 */
void musb_free_request(struct usb_ep *ep, struct usb_request *req)
{
	kfree(to_musb_request(req));
}

static LIST_HEAD(buffers);

struct free_record {
	struct list_head	list;
	struct device		*dev;
	unsigned		bytes;
	dma_addr_t		dma;
};

/*
 * Context: controller locked, IRQs blocked.
 */
void musb_ep_restart(struct musb *musb, struct musb_request *req)
{
	DBG(3, "<== %s request %p len %u on hw_ep%d\n",
		req->tx ? "TX/IN" : "RX/OUT",
		&req->request, req->request.length, req->epnum);

	musb_ep_select(musb->mregs, req->epnum);
	if (req->tx)
		txstate(musb, req);
	else
		rxstate(musb, req);
}

static int musb_gadget_queue(struct usb_ep *ep, struct usb_request *req,
			gfp_t gfp_flags)
{
	struct musb_ep		*musb_ep;
	struct musb_request	*request;
	struct musb		*musb;
	int			status = 0;
	unsigned long		lockflags;

	if (!ep || !req)
		return -EINVAL;
	if (!req->buf)
		return -ENODATA;

	musb_ep = to_musb_ep(ep);
	musb = musb_ep->musb;

	request = to_musb_request(req);
	request->musb = musb;

	if (request->ep != musb_ep)
		return -EINVAL;

	DBG(4, "<== to %s request=%p\n", ep->name, req);

	/* request is mine now... */
	request->request.actual = 0;
	request->request.status = -EINPROGRESS;
	request->epnum = musb_ep->current_epnum;
	request->tx = musb_ep->is_in;

	if (is_dma_capable() && musb_ep->dma)
		map_dma_buffer(request, musb);
	else
		request->mapped = 0;

	spin_lock_irqsave(&musb->lock, lockflags);

	/* don't queue if the ep is down */
	if (!musb_ep->desc) {
		DBG(4, "req %p queued to %s while ep %s\n",
				req, ep->name, "disabled");
		status = -ESHUTDOWN;
		goto cleanup;
	}

	/* add request to the list */
	list_add_tail(&(request->request.list), &(musb_ep->req_list));

	/* it this is the head of the queue, start i/o ... */
	if (!musb_ep->busy && &request->request.list == musb_ep->req_list.next)
		musb_ep_restart(musb, request);

cleanup:
	spin_unlock_irqrestore(&musb->lock, lockflags);
	return status;
}

static int musb_gadget_dequeue(struct usb_ep *ep, struct usb_request *request)
{
	struct musb_ep		*musb_ep = to_musb_ep(ep);
	struct usb_request	*r;
	unsigned long		flags;
	int			status = 0;
	struct musb		*musb = musb_ep->musb;

	if (!ep || !request || to_musb_request(request)->ep != musb_ep)
		return -EINVAL;

	spin_lock_irqsave(&musb->lock, flags);

	list_for_each_entry(r, &musb_ep->req_list, list) {
		if (r == request)
			break;
	}
	if (r != request) {
		DBG(3, "request %p not queued to %s\n", request, ep->name);
		status = -EINVAL;
		goto done;
	}

	/* if the hardware doesn't have the request, easy ... */
	if (musb_ep->req_list.next != &request->list || musb_ep->busy)
		musb_g_giveback(musb_ep, request, -ECONNRESET);

	/* ... else abort the dma transfer ... */
	else if (is_dma_capable() && musb_ep->dma) {
		struct dma_controller	*c = musb->dma_controller;

		musb_ep_select(musb->mregs, musb_ep->current_epnum);
		if (c->channel_abort)
			status = c->channel_abort(musb_ep->dma);
		else
			status = -EBUSY;
		if (status == 0)
			musb_g_giveback(musb_ep, request, -ECONNRESET);
	} else {
		/* NOTE: by sticking to easily tested hardware/driver states,
		 * we leave counting of in-flight packets imprecise.
		 */
		musb_g_giveback(musb_ep, request, -ECONNRESET);
	}

done:
	spin_unlock_irqrestore(&musb->lock, flags);
	return status;
}

/*
 * Set or clear the halt bit of an endpoint. A halted enpoint won't tx/rx any
 * data but will queue requests.
 *
 * exported to ep0 code
 */
static int musb_gadget_set_halt(struct usb_ep *ep, int value)
{
	struct musb_ep		*musb_ep = to_musb_ep(ep);
	u8			epnum = musb_ep->current_epnum;
	struct musb		*musb = musb_ep->musb;
	void __iomem		*epio = musb->endpoints[epnum].regs;
	void __iomem		*mbase;
	unsigned long		flags;
	u16			csr;
	struct musb_request	*request;
	int			status = 0;

	if (!ep)
		return -EINVAL;
	mbase = musb->mregs;

	spin_lock_irqsave(&musb->lock, flags);

	if ((USB_ENDPOINT_XFER_ISOC == musb_ep->type)) {
		status = -EINVAL;
		goto done;
	}

	musb_ep_select(mbase, epnum);

	request = to_musb_request(next_request(musb_ep));
	if (value) {
		if (request) {
			DBG(3, "request in progress, cannot halt %s\n",
			    ep->name);
			status = -EAGAIN;
			goto done;
		}
		/* Cannot portably stall with non-empty FIFO */
		if (musb_ep->is_in) {
			csr = musb_readw(epio, MUSB_TXCSR);
			if (csr & MUSB_TXCSR_FIFONOTEMPTY) {
				DBG(3, "FIFO busy, cannot halt %s\n", ep->name);
				status = -EAGAIN;
				goto done;
			}
		}
	} else
		musb_ep->wedged = 0;

	/* set/clear the stall and toggle bits */
	DBG(2, "%s: %s stall\n", ep->name, value ? "set" : "clear");
	if (musb_ep->is_in) {
		csr = musb_readw(epio, MUSB_TXCSR);
		csr |= MUSB_TXCSR_P_WZC_BITS
			| MUSB_TXCSR_CLRDATATOG;
		if (value)
			csr |= MUSB_TXCSR_P_SENDSTALL;
		else
			csr &= ~(MUSB_TXCSR_P_SENDSTALL
				| MUSB_TXCSR_P_SENTSTALL);
		csr &= ~MUSB_TXCSR_TXPKTRDY;
		musb_writew(epio, MUSB_TXCSR, csr);
	} else {
		csr = musb_readw(epio, MUSB_RXCSR);
		csr |= MUSB_RXCSR_P_WZC_BITS
			| MUSB_RXCSR_FLUSHFIFO
			| MUSB_RXCSR_CLRDATATOG;
		if (value)
			csr |= MUSB_RXCSR_P_SENDSTALL;
		else
			csr &= ~(MUSB_RXCSR_P_SENDSTALL
				| MUSB_RXCSR_P_SENTSTALL);
		musb_writew(epio, MUSB_RXCSR, csr);
	}

	/* maybe start the first request in the queue */
	if (!musb_ep->busy && !value && request) {
		DBG(3, "restarting the request\n");
		musb_ep_restart(musb, request);
	}

done:
	spin_unlock_irqrestore(&musb->lock, flags);
	return status;
}

/*
 * Sets the halt feature with the clear requests ignored
 */
static int musb_gadget_set_wedge(struct usb_ep *ep)
{
	struct musb_ep		*musb_ep = to_musb_ep(ep);

	if (!ep)
		return -EINVAL;

	musb_ep->wedged = 1;

	return usb_ep_set_halt(ep);
}

static int musb_gadget_fifo_status(struct usb_ep *ep)
{
	struct musb_ep		*musb_ep = to_musb_ep(ep);
	void __iomem		*epio = musb_ep->hw_ep->regs;
	int			retval = -EINVAL;

	if (musb_ep->desc && !musb_ep->is_in) {
		struct musb		*musb = musb_ep->musb;
		int			epnum = musb_ep->current_epnum;
		void __iomem		*mbase = musb->mregs;
		unsigned long		flags;

		spin_lock_irqsave(&musb->lock, flags);

		musb_ep_select(mbase, epnum);
		/* FIXME return zero unless RXPKTRDY is set */
		retval = musb_readw(epio, MUSB_RXCOUNT);

		spin_unlock_irqrestore(&musb->lock, flags);
	}
	return retval;
}

static void musb_gadget_fifo_flush(struct usb_ep *ep)
{
	struct musb_ep	*musb_ep = to_musb_ep(ep);
	struct musb	*musb = musb_ep->musb;
	u8		epnum = musb_ep->current_epnum;
	void __iomem	*epio = musb->endpoints[epnum].regs;
	void __iomem	*mbase;
	unsigned long	flags;
	u16		csr, int_txe;

	mbase = musb->mregs;

	spin_lock_irqsave(&musb->lock, flags);
	musb_ep_select(mbase, (u8) epnum);

	/* disable interrupts */
	int_txe = musb_readw(mbase, MUSB_INTRTXE);
	musb_writew(mbase, MUSB_INTRTXE, int_txe & ~(1 << epnum));

	if (musb_ep->is_in) {
		csr = musb_readw(epio, MUSB_TXCSR);
		if (csr & MUSB_TXCSR_FIFONOTEMPTY) {
			csr |= MUSB_TXCSR_FLUSHFIFO | MUSB_TXCSR_P_WZC_BITS;
			musb_writew(epio, MUSB_TXCSR, csr);
			/* REVISIT may be inappropriate w/o FIFONOTEMPTY ... */
			musb_writew(epio, MUSB_TXCSR, csr);
		}
	} else {
		csr = musb_readw(epio, MUSB_RXCSR);
		csr |= MUSB_RXCSR_FLUSHFIFO | MUSB_RXCSR_P_WZC_BITS;
		musb_writew(epio, MUSB_RXCSR, csr);
		musb_writew(epio, MUSB_RXCSR, csr);
	}

	/* re-enable interrupt */
	musb_writew(mbase, MUSB_INTRTXE, int_txe);
	spin_unlock_irqrestore(&musb->lock, flags);
}

static const struct usb_ep_ops musb_ep_ops = {
	.enable		= musb_gadget_enable,
	.disable	= musb_gadget_disable,
	.alloc_request	= musb_alloc_request,
	.free_request	= musb_free_request,
	.queue		= musb_gadget_queue,
	.dequeue	= musb_gadget_dequeue,
	.set_halt	= musb_gadget_set_halt,
	.set_wedge	= musb_gadget_set_wedge,
	.fifo_status	= musb_gadget_fifo_status,
	.fifo_flush	= musb_gadget_fifo_flush
};

/* ----------------------------------------------------------------------- */

static int musb_gadget_get_frame(struct usb_gadget *gadget)
{
	struct musb	*musb = gadget_to_musb(gadget);

	return (int)musb_readw(musb->mregs, MUSB_FRAME);
}

static int musb_gadget_wakeup(struct usb_gadget *gadget)
{
	struct musb	*musb = gadget_to_musb(gadget);
	void __iomem	*mregs = musb->mregs;
	unsigned long	flags;
	int		status = -EINVAL;
	u8		power, devctl;
	int		retries;

	spin_lock_irqsave(&musb->lock, flags);

	switch (musb->xceiv->state) {
	case OTG_STATE_B_PERIPHERAL:
		/* NOTE:  OTG state machine doesn't include B_SUSPENDED;
		 * that's part of the standard usb 1.1 state machine, and
		 * doesn't affect OTG transitions.
		 */
		if (musb->may_wakeup && musb->is_suspended)
			break;
		goto done;
	case OTG_STATE_B_IDLE:
		/* Start SRP ... OTG not required. */
		devctl = musb_readb(mregs, MUSB_DEVCTL);
		DBG(2, "Sending SRP: devctl: %02x\n", devctl);
		devctl |= MUSB_DEVCTL_SESSION;
		musb_writeb(mregs, MUSB_DEVCTL, devctl);
		devctl = musb_readb(mregs, MUSB_DEVCTL);
		retries = 100;
		while (!(devctl & MUSB_DEVCTL_SESSION)) {
			devctl = musb_readb(mregs, MUSB_DEVCTL);
			if (retries-- < 1)
				break;
		}
		retries = 10000;
		while (devctl & MUSB_DEVCTL_SESSION) {
			devctl = musb_readb(mregs, MUSB_DEVCTL);
			if (retries-- < 1)
				break;
		}

		/* Block idling for at least 1s */
		musb_platform_try_idle(musb,
			jiffies + msecs_to_jiffies(1 * HZ));

		status = 0;
		goto done;
	default:
		DBG(2, "Unhandled wake: %s\n", otg_state_string(musb));
		goto done;
	}

	status = 0;

	power = musb_readb(mregs, MUSB_POWER);
	power |= MUSB_POWER_RESUME;
	musb_writeb(mregs, MUSB_POWER, power);
	DBG(2, "issue wakeup\n");

	/* FIXME do this next chunk in a timer callback, no udelay */
	mdelay(2);

	power = musb_readb(mregs, MUSB_POWER);
	power &= ~MUSB_POWER_RESUME;
	musb_writeb(mregs, MUSB_POWER, power);
done:
	spin_unlock_irqrestore(&musb->lock, flags);
	return status;
}

static int
musb_gadget_set_self_powered(struct usb_gadget *gadget, int is_selfpowered)
{
	struct musb	*musb = gadget_to_musb(gadget);

	musb->is_self_powered = !!is_selfpowered;
	return 0;
}

static void musb_pullup(struct musb *musb, int is_on)
{
	u8 power;

	power = musb_readb(musb->mregs, MUSB_POWER);
	if (is_on)
		power |= MUSB_POWER_SOFTCONN;
	else
		power &= ~MUSB_POWER_SOFTCONN;

	/* FIXME if on, HdrcStart; if off, HdrcStop */

	DBG(3, "gadget %s D+ pullup %s\n",
		musb->gadget_driver->function, is_on ? "on" : "off");
	musb_writeb(musb->mregs, MUSB_POWER, power);
}

#if 0
static int musb_gadget_vbus_session(struct usb_gadget *gadget, int is_active)
{
	DBG(2, "<= %s =>\n", __func__);

	/*
	 * FIXME iff driver's softconnect flag is set (as it is during probe,
	 * though that can clear it), just musb_pullup().
	 */

	return -EINVAL;
}
#endif

static int musb_gadget_vbus_draw(struct usb_gadget *gadget, unsigned mA)
{
	struct musb	*musb = gadget_to_musb(gadget);

	if (!musb->xceiv->set_power)
		return -EOPNOTSUPP;
	return otg_set_power(musb->xceiv, mA);
}

static int musb_gadget_pullup(struct usb_gadget *gadget, int is_on)
{
	struct musb	*musb = gadget_to_musb(gadget);
	unsigned long	flags;

	is_on = !!is_on;

	/* NOTE: this assumes we are sensing vbus; we'd rather
	 * not pullup unless the B-session is active.
	 */
	spin_lock_irqsave(&musb->lock, flags);
	if (is_on != musb->softconnect) {
		musb->softconnect = is_on;
		musb_pullup(musb, is_on);
	}
	spin_unlock_irqrestore(&musb->lock, flags);
	return 0;
}

static const struct usb_gadget_ops musb_gadget_operations = {
	.get_frame		= musb_gadget_get_frame,
	.wakeup			= musb_gadget_wakeup,
	.set_selfpowered	= musb_gadget_set_self_powered,
	/* .vbus_session		= musb_gadget_vbus_session, */
	.vbus_draw		= musb_gadget_vbus_draw,
	.pullup			= musb_gadget_pullup,
};

/* ----------------------------------------------------------------------- */

/* Registration */

/* Only this registration code "knows" the rule (from USB standards)
 * about there being only one external upstream port.  It assumes
 * all peripheral ports are external...
 */
static struct musb *the_gadget;

static void musb_gadget_release(struct device *dev)
{
	/* kref_put(WHAT) */
	dev_dbg(dev, "%s\n", __func__);
}


static void __init
init_peripheral_ep(struct musb *musb, struct musb_ep *ep, u8 epnum, int is_in)
{
	struct musb_hw_ep	*hw_ep = musb->endpoints + epnum;

	memset(ep, 0, sizeof *ep);

	ep->current_epnum = epnum;
	ep->musb = musb;
	ep->hw_ep = hw_ep;
	ep->is_in = is_in;

	INIT_LIST_HEAD(&ep->req_list);

	sprintf(ep->name, "ep%d%s", epnum,
			(!epnum || hw_ep->is_shared_fifo) ? "" : (
				is_in ? "in" : "out"));
	ep->end_point.name = ep->name;
	INIT_LIST_HEAD(&ep->end_point.ep_list);
	if (!epnum) {
		ep->end_point.maxpacket = 64;
		ep->end_point.ops = &musb_g_ep0_ops;
		musb->g.ep0 = &ep->end_point;
	} else {
		if (is_in)
			ep->end_point.maxpacket = hw_ep->max_packet_sz_tx;
		else
			ep->end_point.maxpacket = hw_ep->max_packet_sz_rx;
		ep->end_point.ops = &musb_ep_ops;
		list_add_tail(&ep->end_point.ep_list, &musb->g.ep_list);
	}
}

/*
 * Initialize the endpoints exposed to peripheral drivers, with backlinks
 * to the rest of the driver state.
 */
static inline void __init musb_g_init_endpoints(struct musb *musb)
{
	u8			epnum;
	struct musb_hw_ep	*hw_ep;
	unsigned		count = 0;

	/* initialize endpoint list just once */
	INIT_LIST_HEAD(&(musb->g.ep_list));

	for (epnum = 0, hw_ep = musb->endpoints;
			epnum < musb->nr_endpoints;
			epnum++, hw_ep++) {
		if (hw_ep->is_shared_fifo /* || !epnum */) {
			init_peripheral_ep(musb, &hw_ep->ep_in, epnum, 0);
			count++;
		} else {
			if (hw_ep->max_packet_sz_tx) {
				init_peripheral_ep(musb, &hw_ep->ep_in,
							epnum, 1);
				count++;
			}
			if (hw_ep->max_packet_sz_rx) {
				init_peripheral_ep(musb, &hw_ep->ep_out,
							epnum, 0);
				count++;
			}
		}
	}
}

/* called once during driver setup to initialize and link into
 * the driver model; memory is zeroed.
 */
int __init musb_gadget_setup(struct musb *musb)
{
	int status;

	/* REVISIT minor race:  if (erroneously) setting up two
	 * musb peripherals at the same time, only the bus lock
	 * is probably held.
	 */
	if (the_gadget)
		return -EBUSY;
	the_gadget = musb;

	musb->g.ops = &musb_gadget_operations;
	musb->g.is_dualspeed = 1;
	musb->g.speed = USB_SPEED_UNKNOWN;

	/* this "gadget" abstracts/virtualizes the controller */
	dev_set_name(&musb->g.dev, "gadget");
	musb->g.dev.parent = musb->controller;
	musb->g.dev.dma_mask = musb->controller->dma_mask;
	musb->g.dev.release = musb_gadget_release;
	musb->g.name = musb_driver_name;

	if (is_otg_enabled(musb))
		musb->g.is_otg = 1;

	musb_g_init_endpoints(musb);

	musb->is_active = 0;
	musb_platform_try_idle(musb, 0);

	status = device_register(&musb->g.dev);
	if (status != 0) {
		put_device(&musb->g.dev);
		the_gadget = NULL;
	}
	return status;
}

void musb_gadget_cleanup(struct musb *musb)
{
	if (musb != the_gadget)
		return;

	device_unregister(&musb->g.dev);
	the_gadget = NULL;
}

/*
 * Register the gadget driver. Used by gadget drivers when
 * registering themselves with the controller.
 *
 * -EINVAL something went wrong (not driver)
 * -EBUSY another gadget is already using the controller
 * -ENOMEM no memory to perform the operation
 *
 * @param driver the gadget driver
 * @param bind the driver's bind function
 * @return <0 if error, 0 if everything is fine
 */
int usb_gadget_probe_driver(struct usb_gadget_driver *driver,
		int (*bind)(struct usb_gadget *))
{
	int retval;
	unsigned long flags;
	struct musb *musb = the_gadget;

	if (!driver
			|| driver->speed != USB_SPEED_HIGH
			|| !bind || !driver->setup)
		return -EINVAL;

	/* driver must be initialized to support peripheral mode */
	if (!musb) {
		DBG(1, "%s, no dev??\n", __func__);
		return -ENODEV;
	}

	DBG(3, "registering driver %s\n", driver->function);
	spin_lock_irqsave(&musb->lock, flags);

	if (musb->gadget_driver) {
		DBG(1, "%s is already bound to %s\n",
				musb_driver_name,
				musb->gadget_driver->driver.name);
		retval = -EBUSY;
	} else {
		musb->gadget_driver = driver;
		musb->g.dev.driver = &driver->driver;
		driver->driver.bus = NULL;
		musb->softconnect = 1;
		retval = 0;
	}

	spin_unlock_irqrestore(&musb->lock, flags);

	if (retval == 0) {
		retval = bind(&musb->g);
		if (retval != 0) {
			DBG(3, "bind to driver %s failed --> %d\n",
					driver->driver.name, retval);
			musb->gadget_driver = NULL;
			musb->g.dev.driver = NULL;
		}

		spin_lock_irqsave(&musb->lock, flags);

		otg_set_peripheral(musb->xceiv, &musb->g);
		musb->xceiv->state = OTG_STATE_B_IDLE;
		musb->is_active = 1;

		/* FIXME this ignores the softconnect flag.  Drivers are
		 * allowed hold the peripheral inactive until for example
		 * userspace hooks up printer hardware or DSP codecs, so
		 * hosts only see fully functional devices.
		 */

		if (!is_otg_enabled(musb))
			musb_start(musb);

		otg_set_peripheral(musb->xceiv, &musb->g);

		spin_unlock_irqrestore(&musb->lock, flags);

		if (is_otg_enabled(musb)) {
			struct usb_hcd	*hcd = musb_to_hcd(musb);

			DBG(3, "OTG startup...\n");

			/* REVISIT:  funcall to other code, which also
			 * handles power budgeting ... this way also
			 * ensures HdrcStart is indirectly called.
			 */
			retval = usb_add_hcd(musb_to_hcd(musb), -1, 0);
			if (retval < 0) {
				DBG(1, "add_hcd failed, %d\n", retval);
				spin_lock_irqsave(&musb->lock, flags);
				otg_set_peripheral(musb->xceiv, NULL);
				musb->gadget_driver = NULL;
				musb->g.dev.driver = NULL;
				spin_unlock_irqrestore(&musb->lock, flags);
			} else {
				hcd->self.uses_pio_for_control = 1;
			}
		}
	}

	return retval;
}
EXPORT_SYMBOL(usb_gadget_probe_driver);

static void stop_activity(struct musb *musb, struct usb_gadget_driver *driver)
{
	int			i;
	struct musb_hw_ep	*hw_ep;

	/* don't disconnect if it's not connected */
	if (musb->g.speed == USB_SPEED_UNKNOWN)
		driver = NULL;
	else
		musb->g.speed = USB_SPEED_UNKNOWN;

	/* deactivate the hardware */
	if (musb->softconnect) {
		musb->softconnect = 0;
		musb_pullup(musb, 0);
	}
	musb_stop(musb);

	/* killing any outstanding requests will quiesce the driver;
	 * then report disconnect
	 */
	if (driver) {
		for (i = 0, hw_ep = musb->endpoints;
				i < musb->nr_endpoints;
				i++, hw_ep++) {
			musb_ep_select(musb->mregs, i);
			if (hw_ep->is_shared_fifo /* || !epnum */) {
				nuke(&hw_ep->ep_in, -ESHUTDOWN);
			} else {
				if (hw_ep->max_packet_sz_tx)
					nuke(&hw_ep->ep_in, -ESHUTDOWN);
				if (hw_ep->max_packet_sz_rx)
					nuke(&hw_ep->ep_out, -ESHUTDOWN);
			}
		}

		spin_unlock(&musb->lock);
		driver->disconnect(&musb->g);
		spin_lock(&musb->lock);
	}
}

/*
 * Unregister the gadget driver. Used by gadget drivers when
 * unregistering themselves from the controller.
 *
 * @param driver the gadget driver to unregister
 */
int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
{
	unsigned long	flags;
	int		retval = 0;
	struct musb	*musb = the_gadget;

	if (!driver || !driver->unbind || !musb)
		return -EINVAL;

	/* REVISIT always use otg_set_peripheral() here too;
	 * this needs to shut down the OTG engine.
	 */

	spin_lock_irqsave(&musb->lock, flags);

#ifdef	CONFIG_USB_MUSB_OTG
	musb_hnp_stop(musb);
#endif

	if (musb->gadget_driver == driver) {

		(void) musb_gadget_vbus_draw(&musb->g, 0);

		musb->xceiv->state = OTG_STATE_UNDEFINED;
		stop_activity(musb, driver);
		otg_set_peripheral(musb->xceiv, NULL);

		DBG(3, "unregistering driver %s\n", driver->function);
		spin_unlock_irqrestore(&musb->lock, flags);
		driver->unbind(&musb->g);
		spin_lock_irqsave(&musb->lock, flags);

		musb->gadget_driver = NULL;
		musb->g.dev.driver = NULL;

		musb->is_active = 0;
		musb_platform_try_idle(musb, 0);
	} else
		retval = -EINVAL;
	spin_unlock_irqrestore(&musb->lock, flags);

	if (is_otg_enabled(musb) && retval == 0) {
		usb_remove_hcd(musb_to_hcd(musb));
		/* FIXME we need to be able to register another
		 * gadget driver here and have everything work;
		 * that currently misbehaves.
		 */
	}

	return retval;
}
EXPORT_SYMBOL(usb_gadget_unregister_driver);


/* ----------------------------------------------------------------------- */

/* lifecycle operations called through plat_uds.c */

void musb_g_resume(struct musb *musb)
{
	musb->is_suspended = 0;
	switch (musb->xceiv->state) {
	case OTG_STATE_B_IDLE:
		break;
	case OTG_STATE_B_WAIT_ACON:
	case OTG_STATE_B_PERIPHERAL:
		musb->is_active = 1;
		if (musb->gadget_driver && musb->gadget_driver->resume) {
			spin_unlock(&musb->lock);
			musb->gadget_driver->resume(&musb->g);
			spin_lock(&musb->lock);
		}
		break;
	default:
		WARNING("unhandled RESUME transition (%s)\n",
				otg_state_string(musb));
	}
}

/* called when SOF packets stop for 3+ msec */
void musb_g_suspend(struct musb *musb)
{
	u8	devctl;

	devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
	DBG(3, "devctl %02x\n", devctl);

	switch (musb->xceiv->state) {