usb: hsotg: samsung: smp Provide *_lock functions abstraction layer f…

…or 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 <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/s3c-hsotg.c

@@ -895,15 +895,12 @@ static int s3c_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
 	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);
 	req->actual = 0;
@@ -922,11 +919,24 @@ static int s3c_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
 	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,
 				      struct usb_request *req)
 {
@@ -1402,28 +1412,6 @@ static void s3c_hsotg_complete_request(struct s3c_hsotg *hsotg,
 	}
 }
 
-/**
- * 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.
@@ -1443,7 +1431,6 @@ static void s3c_hsotg_rx_data(struct s3c_hsotg *hsotg, int ep_idx, int size)
 	int max_req;
 	int read_ptr;
 
-	spin_lock(&hsotg->lock);
 
 	if (!hs_req) {
 		u32 epctl = readl(hsotg->regs + DOEPCTL(ep_idx));
@@ -1457,7 +1444,6 @@ static void s3c_hsotg_rx_data(struct s3c_hsotg *hsotg, int ep_idx, int size)
 		for (ptr = 0; ptr < size; ptr += 4)
 			(void)readl(fifo);
 
-		spin_unlock(&hsotg->lock);
 		return;
 	}
 
@@ -1487,8 +1473,6 @@ static void s3c_hsotg_rx_data(struct s3c_hsotg *hsotg, int ep_idx, int size)
 	 * alignment of the data.
 	 */
 	readsl(fifo, hs_req->req.buf + read_ptr, to_read);
-
-	spin_unlock(&hsotg->lock);
 }
 
 /**
@@ -1609,7 +1593,7 @@ static void s3c_hsotg_handle_outdone(struct s3c_hsotg *hsotg,
 			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);
 }
 
 /**
@@ -1864,7 +1848,7 @@ static void s3c_hsotg_complete_in(struct s3c_hsotg *hsotg,
 	/* 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;
 	}
 
@@ -1915,7 +1899,7 @@ static void s3c_hsotg_complete_in(struct s3c_hsotg *hsotg,
 		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);
 }
 
 /**
@@ -2123,9 +2107,6 @@ static void kill_all_requests(struct s3c_hsotg *hsotg,
 			      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) {
 		/*
@@ -2139,14 +2120,15 @@ static void kill_all_requests(struct s3c_hsotg *hsotg,
 		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
@@ -2388,6 +2370,7 @@ static irqreturn_t s3c_hsotg_irq(int irq, void *pw)
 	u32 gintsts;
 	u32 gintmsk;
 
+	spin_lock(&hsotg->lock);
 irq_retry:
 	gintsts = readl(hsotg->regs + GINTSTS);
 	gintmsk = readl(hsotg->regs + GINTMSK);
@@ -2557,6 +2540,8 @@ static irqreturn_t s3c_hsotg_irq(int irq, void *pw)
 	if (gintsts & IRQ_RETRY_MASK && --retry_count > 0)
 			goto irq_retry;
 
+	spin_unlock(&hsotg->lock);
+
 	return IRQ_HANDLED;
 }
 
@@ -2710,10 +2695,10 @@ static int s3c_hsotg_ep_disable(struct usb_ep *ep)
 
 	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;
@@ -2784,15 +2769,12 @@ static int s3c_hsotg_ep_sethalt(struct usb_ep *ep, int value)
 	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 */
 
 	epreg = DIEPCTL(index);
@@ -2827,19 +2809,36 @@ static int s3c_hsotg_ep_sethalt(struct usb_ep *ep, int value)
 
 	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 = {
 	.enable		= s3c_hsotg_ep_enable,
 	.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 */
 };