can: xilinx_can: fix recovery from error states not being propagated

The xilinx_can driver contains no mechanism for propagating recovery
from CAN_STATE_ERROR_WARNING and CAN_STATE_ERROR_PASSIVE.

Add such a mechanism by factoring the handling of
XCAN_STATE_ERROR_PASSIVE and XCAN_STATE_ERROR_WARNING out of
xcan_err_interrupt and checking for recovery after RX and TX if the
interface is in one of those states.

Tested with the integrated CAN on Zynq-7000 SoC.

Fixes: b1201e44f50b ("can: xilinx CAN controller support")
Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Cc: <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/xilinx_can.c b/drivers/net/can/xilinx_can.c
index 1bda47a..763408a 100644 (file)
--- a/drivers/net/can/xilinx_can.c
+++ b/drivers/net/can/xilinx_can.c
@@ -2,6 +2,7 @@
  *
  * Copyright (C) 2012 - 2014 Xilinx, Inc.
  * Copyright (C) 2009 PetaLogix. All rights reserved.
+ * Copyright (C) 2017 Sandvik Mining and Construction Oy
  *
  * Description:
  * This driver is developed for Axi CAN IP and for Zynq CANPS Controller.
@@ -529,6 +530,123 @@ static int xcan_rx(struct net_device *ndev)
        return 1;
 }
 
+/**
+ * xcan_current_error_state - Get current error state from HW
+ * @ndev:      Pointer to net_device structure
+ *
+ * Checks the current CAN error state from the HW. Note that this
+ * only checks for ERROR_PASSIVE and ERROR_WARNING.
+ *
+ * Return:
+ * ERROR_PASSIVE or ERROR_WARNING if either is active, ERROR_ACTIVE
+ * otherwise.
+ */
+static enum can_state xcan_current_error_state(struct net_device *ndev)
+{
+       struct xcan_priv *priv = netdev_priv(ndev);
+       u32 status = priv->read_reg(priv, XCAN_SR_OFFSET);
+
+       if ((status & XCAN_SR_ESTAT_MASK) == XCAN_SR_ESTAT_MASK)
+               return CAN_STATE_ERROR_PASSIVE;
+       else if (status & XCAN_SR_ERRWRN_MASK)
+               return CAN_STATE_ERROR_WARNING;
+       else
+               return CAN_STATE_ERROR_ACTIVE;
+}
+
+/**
+ * xcan_set_error_state - Set new CAN error state
+ * @ndev:      Pointer to net_device structure
+ * @new_state: The new CAN state to be set
+ * @cf:                Error frame to be populated or NULL
+ *
+ * Set new CAN error state for the device, updating statistics and
+ * populating the error frame if given.
+ */
+static void xcan_set_error_state(struct net_device *ndev,
+                                enum can_state new_state,
+                                struct can_frame *cf)
+{
+       struct xcan_priv *priv = netdev_priv(ndev);
+       u32 ecr = priv->read_reg(priv, XCAN_ECR_OFFSET);
+       u32 txerr = ecr & XCAN_ECR_TEC_MASK;
+       u32 rxerr = (ecr & XCAN_ECR_REC_MASK) >> XCAN_ESR_REC_SHIFT;
+
+       priv->can.state = new_state;
+
+       if (cf) {
+               cf->can_id |= CAN_ERR_CRTL;
+               cf->data[6] = txerr;
+               cf->data[7] = rxerr;
+       }
+
+       switch (new_state) {
+       case CAN_STATE_ERROR_PASSIVE:
+               priv->can.can_stats.error_passive++;
+               if (cf)
+                       cf->data[1] = (rxerr > 127) ?
+                                       CAN_ERR_CRTL_RX_PASSIVE :
+                                       CAN_ERR_CRTL_TX_PASSIVE;
+               break;
+       case CAN_STATE_ERROR_WARNING:
+               priv->can.can_stats.error_warning++;
+               if (cf)
+                       cf->data[1] |= (txerr > rxerr) ?
+                                       CAN_ERR_CRTL_TX_WARNING :
+                                       CAN_ERR_CRTL_RX_WARNING;
+               break;
+       case CAN_STATE_ERROR_ACTIVE:
+               if (cf)
+                       cf->data[1] |= CAN_ERR_CRTL_ACTIVE;
+               break;
+       default:
+               /* non-ERROR states are handled elsewhere */
+               WARN_ON(1);
+               break;
+       }
+}
+
+/**
+ * xcan_update_error_state_after_rxtx - Update CAN error state after RX/TX
+ * @ndev:      Pointer to net_device structure
+ *
+ * If the device is in a ERROR-WARNING or ERROR-PASSIVE state, check if
+ * the performed RX/TX has caused it to drop to a lesser state and set
+ * the interface state accordingly.
+ */
+static void xcan_update_error_state_after_rxtx(struct net_device *ndev)
+{
+       struct xcan_priv *priv = netdev_priv(ndev);
+       enum can_state old_state = priv->can.state;
+       enum can_state new_state;
+
+       /* changing error state due to successful frame RX/TX can only
+        * occur from these states
+        */
+       if (old_state != CAN_STATE_ERROR_WARNING &&
+           old_state != CAN_STATE_ERROR_PASSIVE)
+               return;
+
+       new_state = xcan_current_error_state(ndev);
+
+       if (new_state != old_state) {
+               struct sk_buff *skb;
+               struct can_frame *cf;
+
+               skb = alloc_can_err_skb(ndev, &cf);
+
+               xcan_set_error_state(ndev, new_state, skb ? cf : NULL);
+
+               if (skb) {
+                       struct net_device_stats *stats = &ndev->stats;
+
+                       stats->rx_packets++;
+                       stats->rx_bytes += cf->can_dlc;
+                       netif_rx(skb);
+               }
+       }
+}
+
 /**
  * xcan_err_interrupt - error frame Isr
  * @ndev:      net_device pointer
@@ -544,16 +662,12 @@ static void xcan_err_interrupt(struct net_device *ndev, u32 isr)
        struct net_device_stats *stats = &ndev->stats;
        struct can_frame *cf;
        struct sk_buff *skb;
-       u32 err_status, status, txerr = 0, rxerr = 0;
+       u32 err_status;
 
        skb = alloc_can_err_skb(ndev, &cf);
 
        err_status = priv->read_reg(priv, XCAN_ESR_OFFSET);
        priv->write_reg(priv, XCAN_ESR_OFFSET, err_status);
-       txerr = priv->read_reg(priv, XCAN_ECR_OFFSET) & XCAN_ECR_TEC_MASK;
-       rxerr = ((priv->read_reg(priv, XCAN_ECR_OFFSET) &
-                       XCAN_ECR_REC_MASK) >> XCAN_ESR_REC_SHIFT);
-       status = priv->read_reg(priv, XCAN_SR_OFFSET);
 
        if (isr & XCAN_IXR_BSOFF_MASK) {
                priv->can.state = CAN_STATE_BUS_OFF;
@@ -563,28 +677,10 @@ static void xcan_err_interrupt(struct net_device *ndev, u32 isr)
                can_bus_off(ndev);
                if (skb)
                        cf->can_id |= CAN_ERR_BUSOFF;
-       } else if ((status & XCAN_SR_ESTAT_MASK) == XCAN_SR_ESTAT_MASK) {
-               priv->can.state = CAN_STATE_ERROR_PASSIVE;
-               priv->can.can_stats.error_passive++;
-               if (skb) {
-                       cf->can_id |= CAN_ERR_CRTL;
-                       cf->data[1] = (rxerr > 127) ?
-                                       CAN_ERR_CRTL_RX_PASSIVE :
-                                       CAN_ERR_CRTL_TX_PASSIVE;
-                       cf->data[6] = txerr;
-                       cf->data[7] = rxerr;
-               }
-       } else if (status & XCAN_SR_ERRWRN_MASK) {
-               priv->can.state = CAN_STATE_ERROR_WARNING;
-               priv->can.can_stats.error_warning++;
-               if (skb) {
-                       cf->can_id |= CAN_ERR_CRTL;
-                       cf->data[1] |= (txerr > rxerr) ?
-                                       CAN_ERR_CRTL_TX_WARNING :
-                                       CAN_ERR_CRTL_RX_WARNING;
-                       cf->data[6] = txerr;
-                       cf->data[7] = rxerr;
-               }
+       } else {
+               enum can_state new_state = xcan_current_error_state(ndev);
+
+               xcan_set_error_state(ndev, new_state, skb ? cf : NULL);
        }
 
        /* Check for Arbitration lost interrupt */
@@ -713,8 +809,10 @@ static int xcan_rx_poll(struct napi_struct *napi, int quota)
                isr = priv->read_reg(priv, XCAN_ISR_OFFSET);
        }
 
-       if (work_done)
+       if (work_done) {
                can_led_event(ndev, CAN_LED_EVENT_RX);
+               xcan_update_error_state_after_rxtx(ndev);
+       }
 
        if (work_done < quota) {
                napi_complete_done(napi, work_done);
@@ -745,6 +843,7 @@ static void xcan_tx_interrupt(struct net_device *ndev, u32 isr)
                isr = priv->read_reg(priv, XCAN_ISR_OFFSET);
        }
        can_led_event(ndev, CAN_LED_EVENT_TX);
+       xcan_update_error_state_after_rxtx(ndev);
        netif_wake_queue(ndev);
 }