usb: hsotg: samsung: smp Provide *_lock functions abstraction layer for SMP SoCs

For SMP processors the spin_lock_irqsave is _only_ able to disable interrupt
on a core on which it is executed.

Therefore there may be a situation when other cores raise s3c-hsotg IRQ.
Then there are several places where critical sections can be overwritten.

To protect the above thread, a spin_lock in the interrupt handler has been
added. Due to coherent memory view (especially L1 cache) the spin lock
variable control access to IRQ handler only for one CPU core. In this way
serialization to access this driver is provided and hence several spin_lock_*
routines could be removed from IRQ handler's related functions.

The complete_request_lock function has been removed since all its calls
are performed from interrupt (spin lock protected) context.

Signed-off-by: Lukasz Majewski <[e-mail]>
Signed-off-by: Kyungmin Park <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/s3c-hsotg.c

···
 	struct s3c_hsotg_req *hs_req = our_req(req);
 	struct s3c_hsotg_ep *hs_ep = our_ep(ep);
 	struct s3c_hsotg *hs = hs_ep->parent;
-	unsigned long irqflags;
 	bool first;
 
 	dev_dbg(hs->dev, "%s: req %p: %d@%p, noi=%d, zero=%d, snok=%d\n",
 		ep->name, req, req->length, req->buf, req->no_interrupt,
 		req->zero, req->short_not_ok);
-
-	spin_lock_irqsave(&hs->lock, irqflags);
 
 	/* initialise status of the request */
 	INIT_LIST_HEAD(&hs_req->queue);
···
 	if (first)
 		s3c_hsotg_start_req(hs, hs_ep, hs_req, false);
 
-	spin_unlock_irqrestore(&hs->lock, irqflags);
-
 	return 0;
+}
+
+static int s3c_hsotg_ep_queue_lock(struct usb_ep *ep, struct usb_request *req,
+			      gfp_t gfp_flags)
+{
+	struct s3c_hsotg_ep *hs_ep = our_ep(ep);
+	struct s3c_hsotg *hs = hs_ep->parent;
+	unsigned long flags = 0;
+	int ret = 0;
+
+	spin_lock_irqsave(&hs->lock, flags);
+	ret = s3c_hsotg_ep_queue(ep, req, gfp_flags);
+	spin_unlock_irqrestore(&hs->lock, flags);
+
+	return ret;
 }
 
 static void s3c_hsotg_ep_free_request(struct usb_ep *ep,
···
 }
 
 /**
- * s3c_hsotg_complete_request_lock - complete a request given to us (locked)
- * @hsotg: The device state.
- * @hs_ep: The endpoint the request was on.
- * @hs_req: The request to complete.
- * @result: The result code (0 => Ok, otherwise errno)
- *
- * See s3c_hsotg_complete_request(), but called with the endpoint's
- * lock held.
- */
-static void s3c_hsotg_complete_request_lock(struct s3c_hsotg *hsotg,
-					    struct s3c_hsotg_ep *hs_ep,
-					    struct s3c_hsotg_req *hs_req,
-					    int result)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&hsotg->lock, flags);
-	s3c_hsotg_complete_request(hsotg, hs_ep, hs_req, result);
-	spin_unlock_irqrestore(&hsotg->lock, flags);
-}
-
-/**
  * s3c_hsotg_rx_data - receive data from the FIFO for an endpoint
  * @hsotg: The device state.
  * @ep_idx: The endpoint index for the data
···
 	int max_req;
 	int read_ptr;
 
-	spin_lock(&hsotg->lock);
 
 	if (!hs_req) {
 		u32 epctl = readl(hsotg->regs + DOEPCTL(ep_idx));
···
 		for (ptr = 0; ptr < size; ptr += 4)
 			(void)readl(fifo);
 
-		spin_unlock(&hsotg->lock);
 		return;
 	}
 
···
 	 * alignment of the data.
 	 */
 	readsl(fifo, hs_req->req.buf + read_ptr, to_read);
-
-	spin_unlock(&hsotg->lock);
 }
 
 /**
···
 			s3c_hsotg_send_zlp(hsotg, hs_req);
 	}
 
-	s3c_hsotg_complete_request_lock(hsotg, hs_ep, hs_req, result);
+	s3c_hsotg_complete_request(hsotg, hs_ep, hs_req, result);
 }
 
 /**
···
 	/* Finish ZLP handling for IN EP0 transactions */
 	if (hsotg->eps[0].sent_zlp) {
 		dev_dbg(hsotg->dev, "zlp packet received\n");
-		s3c_hsotg_complete_request_lock(hsotg, hs_ep, hs_req, 0);
+		s3c_hsotg_complete_request(hsotg, hs_ep, hs_req, 0);
 		return;
 	}
 
···
 		dev_dbg(hsotg->dev, "%s trying more for req...\n", __func__);
 		s3c_hsotg_start_req(hsotg, hs_ep, hs_req, true);
 	} else
-		s3c_hsotg_complete_request_lock(hsotg, hs_ep, hs_req, 0);
+		s3c_hsotg_complete_request(hsotg, hs_ep, hs_req, 0);
 }
 
 /**
···
 			      int result, bool force)
 {
 	struct s3c_hsotg_req *req, *treq;
-	unsigned long flags;
-
-	spin_lock_irqsave(&hsotg->lock, flags);
 
 	list_for_each_entry_safe(req, treq, &ep->queue, queue) {
 		/*
···
 		s3c_hsotg_complete_request(hsotg, ep, req,
 					   result);
 	}
-
-	spin_unlock_irqrestore(&hsotg->lock, flags);
 }
 
 #define call_gadget(_hs, _entry) \
 	if ((_hs)->gadget.speed != USB_SPEED_UNKNOWN &&	\
-	    (_hs)->driver && (_hs)->driver->_entry)	\
-		(_hs)->driver->_entry(&(_hs)->gadget);
+	    (_hs)->driver && (_hs)->driver->_entry) { \
+		spin_unlock(&_hs->lock); \
+		(_hs)->driver->_entry(&(_hs)->gadget); \
+		spin_lock(&_hs->lock); \
+		}
 
 /**
  * s3c_hsotg_disconnect - disconnect service
···
 	u32 gintsts;
 	u32 gintmsk;
 
+	spin_lock(&hsotg->lock);
 irq_retry:
 	gintsts = readl(hsotg->regs + GINTSTS);
 	gintmsk = readl(hsotg->regs + GINTMSK);
···
 	if (gintsts & IRQ_RETRY_MASK && --retry_count > 0)
 			goto irq_retry;
 
+	spin_unlock(&hsotg->lock);
+
 	return IRQ_HANDLED;
 }
 
···
 
 	epctrl_reg = dir_in ? DIEPCTL(index) : DOEPCTL(index);
 
+	spin_lock_irqsave(&hsotg->lock, flags);
 	/* terminate all requests with shutdown */
 	kill_all_requests(hsotg, hs_ep, -ESHUTDOWN, false);
 
-	spin_lock_irqsave(&hsotg->lock, flags);
 
 	ctrl = readl(hsotg->regs + epctrl_reg);
 	ctrl &= ~DxEPCTL_EPEna;
···
 	struct s3c_hsotg_ep *hs_ep = our_ep(ep);
 	struct s3c_hsotg *hs = hs_ep->parent;
 	int index = hs_ep->index;
-	unsigned long irqflags;
 	u32 epreg;
 	u32 epctl;
 	u32 xfertype;
 
 	dev_info(hs->dev, "%s(ep %p %s, %d)\n", __func__, ep, ep->name, value);
-
-	spin_lock_irqsave(&hs->lock, irqflags);
 
 	/* write both IN and OUT control registers */
 
···
 
 	writel(epctl, hs->regs + epreg);
 
-	spin_unlock_irqrestore(&hs->lock, irqflags);
-
 	return 0;
+}
+
+/**
+ * s3c_hsotg_ep_sethalt_lock - set halt on a given endpoint with lock held
+ * @ep: The endpoint to set halt.
+ * @value: Set or unset the halt.
+ */
+static int s3c_hsotg_ep_sethalt_lock(struct usb_ep *ep, int value)
+{
+	struct s3c_hsotg_ep *hs_ep = our_ep(ep);
+	struct s3c_hsotg *hs = hs_ep->parent;
+	unsigned long flags = 0;
+	int ret = 0;
+
+	spin_lock_irqsave(&hs->lock, flags);
+	ret = s3c_hsotg_ep_sethalt(ep, value);
+	spin_unlock_irqrestore(&hs->lock, flags);
+
+	return ret;
 }
 
 static struct usb_ep_ops s3c_hsotg_ep_ops = {
···
 	.disable	= s3c_hsotg_ep_disable,
 	.alloc_request	= s3c_hsotg_ep_alloc_request,
 	.free_request	= s3c_hsotg_ep_free_request,
-	.queue		= s3c_hsotg_ep_queue,
+	.queue		= s3c_hsotg_ep_queue_lock,
 	.dequeue	= s3c_hsotg_ep_dequeue,
-	.set_halt	= s3c_hsotg_ep_sethalt,
+	.set_halt	= s3c_hsotg_ep_sethalt_lock,
 	/* note, don't believe we have any call for the fifo routines */
 };