net: macb: Handle HRESP error

Handle HRESP error by doing a SW reset of RX and TX and
re-initializing the descriptors, RX and TX queue pointers.

Signed-off-by: Harini Katakam <harinik@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: harini-katakam

drivers/net/ethernet/cadence/macb.h

@@ -13,6 +13,7 @@
 #include <linux/phy.h>
 #include <linux/ptp_clock_kernel.h>
 #include <linux/net_tstamp.h>
+#include <linux/interrupt.h>
 
 #if defined(CONFIG_ARCH_DMA_ADDR_T_64BIT) || defined(CONFIG_MACB_USE_HWSTAMP)
 #define MACB_EXT_DESC
@@ -1200,6 +1201,8 @@ struct macb {
 	struct ethtool_rx_fs_list rx_fs_list;
 	spinlock_t rx_fs_lock;
 	unsigned int max_tuples;
+
+	struct tasklet_struct	hresp_err_tasklet;
 };
 
 #ifdef CONFIG_MACB_USE_HWSTAMP

drivers/net/ethernet/cadence/macb_main.c

@@ -1258,6 +1258,57 @@ static int macb_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
+static void macb_hresp_error_task(unsigned long data)
+{
+	struct macb *bp = (struct macb *)data;
+	struct net_device *dev = bp->dev;
+	struct macb_queue *queue = bp->queues;
+	unsigned int q;
+	u32 ctrl;
+
+	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
+		queue_writel(queue, IDR, MACB_RX_INT_FLAGS |
+					 MACB_TX_INT_FLAGS |
+					 MACB_BIT(HRESP));
+	}
+	ctrl = macb_readl(bp, NCR);
+	ctrl &= ~(MACB_BIT(RE) | MACB_BIT(TE));
+	macb_writel(bp, NCR, ctrl);
+
+	netif_tx_stop_all_queues(dev);
+	netif_carrier_off(dev);
+
+	bp->macbgem_ops.mog_init_rings(bp);
+
+	/* Initialize TX and RX buffers */
+	for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
+		queue_writel(queue, RBQP, lower_32_bits(queue->rx_ring_dma));
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+		if (bp->hw_dma_cap & HW_DMA_CAP_64B)
+			queue_writel(queue, RBQPH,
+				     upper_32_bits(queue->rx_ring_dma));
+#endif
+		queue_writel(queue, TBQP, lower_32_bits(queue->tx_ring_dma));
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+		if (bp->hw_dma_cap & HW_DMA_CAP_64B)
+			queue_writel(queue, TBQPH,
+				     upper_32_bits(queue->tx_ring_dma));
+#endif
+
+		/* Enable interrupts */
+		queue_writel(queue, IER,
+			     MACB_RX_INT_FLAGS |
+			     MACB_TX_INT_FLAGS |
+			     MACB_BIT(HRESP));
+	}
+
+	ctrl |= MACB_BIT(RE) | MACB_BIT(TE);
+	macb_writel(bp, NCR, ctrl);
+
+	netif_carrier_on(dev);
+	netif_tx_start_all_queues(dev);
+}
+
 static irqreturn_t macb_interrupt(int irq, void *dev_id)
 {
 	struct macb_queue *queue = dev_id;
@@ -1347,10 +1398,7 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
 		}
 
 		if (status & MACB_BIT(HRESP)) {
-			/* TODO: Reset the hardware, and maybe move the
-			 * netdev_err to a lower-priority context as well
-			 * (work queue?)
-			 */
+			tasklet_schedule(&bp->hresp_err_tasklet);
 			netdev_err(dev, "DMA bus error: HRESP not OK\n");
 
 			if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
@@ -3937,6 +3985,9 @@ static int macb_probe(struct platform_device *pdev)
 		goto err_out_unregister_mdio;
 	}
 
+	tasklet_init(&bp->hresp_err_tasklet, macb_hresp_error_task,
+		     (unsigned long)bp);
+
 	phy_attached_info(phydev);
 
 	netdev_info(dev, "Cadence %s rev 0x%08x at 0x%08lx irq %d (%pM)\n",