1 files changed, 60 insertions, 18 deletions

diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
index af0a80ddf594..0e79eebfcbb7 100644
--- a/drivers/thunderbolt/nhi.c
+++ b/drivers/thunderbolt/nhi.c
@@ -26,6 +26,8 @@
  * use this ring for anything else.
  */
 #define RING_E2E_UNUSED_HOPID	2
+/* HopIDs 0-7 are reserved by the Thunderbolt protocol */
+#define RING_FIRST_USABLE_HOPID	8
 
 /*
  * Minimal number of vectors when we use MSI-X. Two for control channel
@@ -411,6 +413,62 @@ static void ring_release_msix(struct tb_ring *ring)
 	ring->irq = 0;
 }
 
+static int nhi_alloc_hop(struct tb_nhi *nhi, struct tb_ring *ring)
+{
+	int ret = 0;
+
+	spin_lock_irq(&nhi->lock);
+
+	if (ring->hop < 0) {
+		unsigned int i;
+
+		/*
+		 * Automatically allocate HopID from the non-reserved
+		 * range 8 .. hop_count - 1.
+		 */
+		for (i = RING_FIRST_USABLE_HOPID; i < nhi->hop_count; i++) {
+			if (ring->is_tx) {
+				if (!nhi->tx_rings[i]) {
+					ring->hop = i;
+					break;
+				}
+			} else {
+				if (!nhi->rx_rings[i]) {
+					ring->hop = i;
+					break;
+				}
+			}
+		}
+	}
+
+	if (ring->hop < 0 || ring->hop >= nhi->hop_count) {
+		dev_warn(&nhi->pdev->dev, "invalid hop: %d\n", ring->hop);
+		ret = -EINVAL;
+		goto err_unlock;
+	}
+	if (ring->is_tx && nhi->tx_rings[ring->hop]) {
+		dev_warn(&nhi->pdev->dev, "TX hop %d already allocated\n",
+			 ring->hop);
+		ret = -EBUSY;
+		goto err_unlock;
+	} else if (!ring->is_tx && nhi->rx_rings[ring->hop]) {
+		dev_warn(&nhi->pdev->dev, "RX hop %d already allocated\n",
+			 ring->hop);
+		ret = -EBUSY;
+		goto err_unlock;
+	}
+
+	if (ring->is_tx)
+		nhi->tx_rings[ring->hop] = ring;
+	else
+		nhi->rx_rings[ring->hop] = ring;
+
+err_unlock:
+	spin_unlock_irq(&nhi->lock);
+
+	return ret;
+}
+
 static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
 				     bool transmit, unsigned int flags,
 				     u16 sof_mask, u16 eof_mask,
@@ -456,28 +514,12 @@ static struct tb_ring *tb_ring_alloc(struct tb_nhi *nhi, u32 hop, int size,
 	if (ring_request_msix(ring, flags & RING_FLAG_NO_SUSPEND))
 		goto err_free_descs;
 
-	spin_lock_irq(&nhi->lock);
-	if (hop >= nhi->hop_count) {
-		dev_WARN(&nhi->pdev->dev, "invalid hop: %d\n", hop);
+	if (nhi_alloc_hop(nhi, ring))
 		goto err_release_msix;
-	}
-	if (transmit && nhi->tx_rings[hop]) {
-		dev_WARN(&nhi->pdev->dev, "TX hop %d already allocated\n", hop);
-		goto err_release_msix;
-	} else if (!transmit && nhi->rx_rings[hop]) {
-		dev_WARN(&nhi->pdev->dev, "RX hop %d already allocated\n", hop);
-		goto err_release_msix;
-	}
-	if (transmit)
-		nhi->tx_rings[hop] = ring;
-	else
-		nhi->rx_rings[hop] = ring;
-	spin_unlock_irq(&nhi->lock);
 
 	return ring;
 
 err_release_msix:
-	spin_unlock_irq(&nhi->lock);
 	ring_release_msix(ring);
 err_free_descs:
 	dma_free_coherent(&ring->nhi->pdev->dev,
@@ -506,7 +548,7 @@ EXPORT_SYMBOL_GPL(tb_ring_alloc_tx);
 /**
  * tb_ring_alloc_rx() - Allocate DMA ring for receive
  * @nhi: Pointer to the NHI the ring is to be allocated
- * @hop: HopID (ring) to allocate
+ * @hop: HopID (ring) to allocate. Pass %-1 for automatic allocation.
  * @size: Number of entries in the ring
  * @flags: Flags for the ring
  * @sof_mask: Mask of PDF values that start a frame