rt2800: initial watchdog implementation

Add watchdog for rt2800 devices. For now it only detect hung
and print error.

[Note: I verified that printing messages from process context is
fine on MT7620 (WT3020) platform that have problem when printk
is called from interrupt context].
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ralink/rt2x00/rt2800lib.c

@@ -1212,6 +1212,60 @@ void rt2800_txdone_nostatus(struct rt2x00_dev *rt2x00dev)
 }
 EXPORT_SYMBOL_GPL(rt2800_txdone_nostatus);
 
+static int rt2800_check_hung(struct data_queue *queue)
+{
+	unsigned int cur_idx = rt2800_drv_get_dma_done(queue);
+
+	if (queue->wd_idx != cur_idx)
+		queue->wd_count = 0;
+	else
+		queue->wd_count++;
+
+	return queue->wd_count > 16;
+}
+
+void rt2800_watchdog(struct rt2x00_dev *rt2x00dev)
+{
+	struct data_queue *queue;
+	bool hung_tx = false;
+	bool hung_rx = false;
+
+	if (test_bit(DEVICE_STATE_SCANNING, &rt2x00dev->flags))
+		return;
+
+	queue_for_each(rt2x00dev, queue) {
+		switch (queue->qid) {
+		case QID_AC_VO:
+		case QID_AC_VI:
+		case QID_AC_BE:
+		case QID_AC_BK:
+		case QID_MGMT:
+			if (rt2x00queue_empty(queue))
+				continue;
+			hung_tx = rt2800_check_hung(queue);
+			break;
+		case QID_RX:
+			/* For station mode we should reactive at least
+			 * beacons. TODO: need to find good way detect
+			 * RX hung for AP mode.
+			 */
+			if (rt2x00dev->intf_sta_count == 0)
+				continue;
+			hung_rx = rt2800_check_hung(queue);
+			break;
+		default:
+			break;
+		}
+	}
+
+	if (hung_tx)
+		rt2x00_warn(rt2x00dev, "Watchdog TX hung detected\n");
+
+	if (hung_rx)
+		rt2x00_warn(rt2x00dev, "Watchdog RX hung detected\n");
+}
+EXPORT_SYMBOL_GPL(rt2800_watchdog);
+
 static unsigned int rt2800_hw_beacon_base(struct rt2x00_dev *rt2x00dev,
 					  unsigned int index)
 {
@@ -10211,6 +10265,8 @@ int rt2800_probe_hw(struct rt2x00_dev *rt2x00dev)
 		__set_bit(REQUIRE_TASKLET_CONTEXT, &rt2x00dev->cap_flags);
 	}
 
+	rt2x00dev->link.watchdog_interval = msecs_to_jiffies(100);
+
 	/*
 	 * Set the rssi offset.
 	 */

drivers/net/wireless/ralink/rt2x00/rt2800lib.h

@@ -197,6 +197,8 @@ void rt2800_txdone_nostatus(struct rt2x00_dev *rt2x00dev);
 bool rt2800_txstatus_timeout(struct rt2x00_dev *rt2x00dev);
 bool rt2800_txstatus_pending(struct rt2x00_dev *rt2x00dev);
 
+void rt2800_watchdog(struct rt2x00_dev *rt2x00dev);
+
 void rt2800_write_beacon(struct queue_entry *entry, struct txentry_desc *txdesc);
 void rt2800_clear_beacon(struct queue_entry *entry);
 

drivers/net/wireless/ralink/rt2x00/rt2800pci.c

@@ -351,6 +351,7 @@ static const struct rt2x00lib_ops rt2800pci_rt2x00_ops = {
 	.link_tuner		= rt2800_link_tuner,
 	.gain_calibration	= rt2800_gain_calibration,
 	.vco_calibration	= rt2800_vco_calibration,
+	.watchdog		= rt2800_watchdog,
 	.start_queue		= rt2800mmio_start_queue,
 	.kick_queue		= rt2800mmio_kick_queue,
 	.stop_queue		= rt2800mmio_stop_queue,

drivers/net/wireless/ralink/rt2x00/rt2800soc.c

@@ -196,6 +196,7 @@ static const struct rt2x00lib_ops rt2800soc_rt2x00_ops = {
 	.link_tuner		= rt2800_link_tuner,
 	.gain_calibration	= rt2800_gain_calibration,
 	.vco_calibration	= rt2800_vco_calibration,
+	.watchdog		= rt2800_watchdog,
 	.start_queue		= rt2800mmio_start_queue,
 	.kick_queue		= rt2800mmio_kick_queue,
 	.stop_queue		= rt2800mmio_stop_queue,

drivers/net/wireless/ralink/rt2x00/rt2800usb.c

@@ -687,6 +687,7 @@ static const struct rt2x00lib_ops rt2800usb_rt2x00_ops = {
 	.link_tuner		= rt2800_link_tuner,
 	.gain_calibration	= rt2800_gain_calibration,
 	.vco_calibration	= rt2800_vco_calibration,
+	.watchdog		= rt2800_watchdog,
 	.start_queue		= rt2800usb_start_queue,
 	.kick_queue		= rt2x00usb_kick_queue,
 	.stop_queue		= rt2800usb_stop_queue,

drivers/net/wireless/ralink/rt2x00/rt2x00queue.h

@@ -435,6 +435,9 @@ enum data_queue_flags {
  * @length: Number of frames in queue.
  * @index: Index pointers to entry positions in the queue,
  *	use &enum queue_index to get a specific index field.
+ * @wd_count: watchdog counter number of times entry does change
+ *      in the queue
+ * @wd_idx: index of queue entry saved by watchdog
  * @txop: maximum burst time.
  * @aifs: The aifs value for outgoing frames (field ignored in RX queue).
  * @cw_min: The cw min value for outgoing frames (field ignored in RX queue).
@@ -462,6 +465,9 @@ struct data_queue {
 	unsigned short length;
 	unsigned short index[Q_INDEX_MAX];
 
+	unsigned short wd_count;
+	unsigned int wd_idx;
+
 	unsigned short txop;
 	unsigned short aifs;
 	unsigned short cw_min;