NFC: pn533: Add pn533_abort_cmd procedure

pn533_abort_cmd() aborts last command sent to the controller
and cancels already requested urb.

As ACR122U does not support any mechanism (as ACK for standard
PN533) which aborts last command this cannot be issued for this
device. Otherwise, acr122u will behave in an unstable way.
Signed-off-by: NWaldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/nfc/pn533.c

@@ -1113,6 +1113,23 @@ static void pn533_send_complete(struct urb *urb)
 	}
 }
 
+static void pn533_abort_cmd(struct pn533 *dev, gfp_t flags)
+{
+	/* ACR122U does not support any command which aborts last
+	 * issued command i.e. as ACK for standard PN533. Additionally,
+	 * it behaves stange, sending broken or incorrect responses,
+	 * when we cancel urb before the chip will send response.
+	 */
+	if (dev->device_type == PN533_DEVICE_ACR122U)
+		return;
+
+	/* An ack will cancel the last issued command */
+	pn533_send_ack(dev, flags);
+
+	/* cancel the urb request */
+	usb_kill_urb(dev->in_urb);
+}
+
 static struct sk_buff *pn533_alloc_skb(struct pn533 *dev, unsigned int size)
 {
 	struct sk_buff *skb;
@@ -1631,9 +1648,6 @@ static void pn533_listen_mode_timer(unsigned long data)
 
 	nfc_dev_dbg(&dev->interface->dev, "Listen mode timeout");
 
-	/* An ack will cancel the last issued command (poll) */
-	pn533_send_ack(dev, GFP_ATOMIC);
-
 	dev->cancel_listen = 1;
 
 	pn533_poll_next_mod(dev);
@@ -1763,7 +1777,7 @@ static void pn533_wq_poll(struct work_struct *work)
 
 	if (dev->cancel_listen == 1) {
 		dev->cancel_listen = 0;
-		usb_kill_urb(dev->in_urb);
+		pn533_abort_cmd(dev, GFP_ATOMIC);
 	}
 
 	rc = pn533_send_poll_frame(dev);
@@ -1825,12 +1839,7 @@ static void pn533_stop_poll(struct nfc_dev *nfc_dev)
 		return;
 	}
 
-	/* An ack will cancel the last issued command (poll) */
-	pn533_send_ack(dev, GFP_KERNEL);
-
-	/* prevent pn533_start_poll_complete to issue a new poll meanwhile */
-	usb_kill_urb(dev->in_urb);
-
+	pn533_abort_cmd(dev, GFP_KERNEL);
 	pn533_poll_reset_mod_list(dev);
 }
 
@@ -2123,10 +2132,8 @@ static int pn533_dep_link_down(struct nfc_dev *nfc_dev)
 
 	pn533_poll_reset_mod_list(dev);
 
-	if (dev->tgt_mode || dev->tgt_active_prot) {
-		pn533_send_ack(dev, GFP_KERNEL);
-		usb_kill_urb(dev->in_urb);
-	}
+	if (dev->tgt_mode || dev->tgt_active_prot)
+		pn533_abort_cmd(dev, GFP_KERNEL);
 
 	dev->tgt_active_prot = 0;
 	dev->tgt_mode = 0;