[PATCH 5/6] usb: musb: gadget: implement send_response

[Paul Elder]

This patch implements a mechanism to signal the MUSB driver to reply to
a control OUT request with STALL or ACK.

Signed-off-by: Paul Elder <paul.el...@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
---
 drivers/usb/musb/musb_gadget_ep0.c | 41 ++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/usb/musb/musb_gadget_ep0.c 
b/drivers/usb/musb/musb_gadget_ep0.c
index 91a5027b5c1f..f0ed1f7472a3 100644
--- a/drivers/usb/musb/musb_gadget_ep0.c
+++ b/drivers/usb/musb/musb_gadget_ep0.c
@@ -458,6 +458,25 @@ __acquires(musb->lock)
        return handled;
 }
 
+static int ep0_send_response(struct musb *musb, bool stall)
+{
+       void __iomem *regs = musb->control_ep->regs;
+       u16 ackpend;
+
+       if (musb->ep0_state != MUSB_EP0_STAGE_RX &&
+           musb->ep0_state != MUSB_EP0_STAGE_STATUSIN)
+               return -EINVAL;
+
+       ackpend = MUSB_CSR0_P_DATAEND
+               | MUSB_CSR0_P_SVDRXPKTRDY
+               | (stall ? MUSB_CSR0_P_SENDSTALL : 0);
+
+       musb_ep_select(musb->mregs, 0);
+       musb_writew(regs, MUSB_CSR0, ackpend);
+
+       return 0;
+}
+
 /* we have an ep0out data packet
  * Context:  caller holds controller lock
  */
@@ -466,10 +485,13 @@ static void ep0_rxstate(struct musb *musb)
        void __iomem            *regs = musb->control_ep->regs;
        struct musb_request     *request;
        struct usb_request      *req;
+       struct usb_ep           *ep;
        u16                     count, csr;
+       bool                    last_packet = false;
 
        request = next_ep0_request(musb);
        req = &request->request;
+       ep = &request->ep->end_point;
 
        /* read packet and ack; or stall because of gadget driver bug:
         * should have provided the rx buffer before setup() returned.
@@ -492,6 +514,7 @@ static void ep0_rxstate(struct musb *musb)
                if (count < 64 || req->actual == req->length) {
                        musb->ep0_state = MUSB_EP0_STAGE_STATUSIN;
                        csr |= MUSB_CSR0_P_DATAEND;
+                       last_packet = true;
                } else
                        req = NULL;
        } else
@@ -508,6 +531,10 @@ static void ep0_rxstate(struct musb *musb)
                        return;
                musb->ackpend = 0;
        }
+
+       if (last_packet && ep->delayed_status)
+               return;
+
        musb_ep_select(musb->mregs, 0);
        musb_writew(regs, MUSB_CSR0, csr);
 }
@@ -991,6 +1018,19 @@ static int musb_g_ep0_dequeue(struct usb_ep *ep, struct 
usb_request *req)
        return -EINVAL;
 }
 
+static int musb_g_ep0_send_response(struct usb_ep *e, bool stall)
+{
+       struct musb_ep *ep = to_musb_ep(e);
+       struct musb *musb = ep->musb;
+       unsigned long flags;
+       int ret;
+
+       spin_lock_irqsave(&musb->lock, flags);
+       ret = ep0_send_response(musb, stall);
+       spin_unlock_irqrestore(&musb->lock, flags);
+       return ret;
+}
+
 static int musb_g_ep0_halt(struct usb_ep *e, int value)
 {
        struct musb_ep          *ep;
@@ -1059,4 +1099,5 @@ const struct usb_ep_ops musb_g_ep0_ops = {
        .queue          = musb_g_ep0_queue,
        .dequeue        = musb_g_ep0_dequeue,
        .set_halt       = musb_g_ep0_halt,
+       .send_response  = musb_g_ep0_send_response,
 };
-- 
2.18.0