[PATCH 3.16 283/366] can: xilinx_can: fix recovery from error states not being propagated

Ben Hutchings
2018-11-11T20:25:37Z

From: Anssi Hannula <anssi.hannula@bitwise.fi>

commit 877e0b75947e2c7acf5624331bb17ceb093c98ae upstream.

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>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/net/can/xilinx_can.c | 155 ++++++++++++++++++++++++++++-------
1 file changed, 127 insertions(+), 28 deletions(-)

--- 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.
@@ -528,6 +529,123 @@ static int xcan_rx(struct net_device *nd
}

/**
+ * 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
* @isr: interrupt status register value
@@ -542,16 +660,12 @@ static void xcan_err_interrupt(struct ne
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;
@@ -561,28 +675,10 @@ static void xcan_err_interrupt(struct ne
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 */
@@ -714,8 +810,10 @@ static int xcan_rx_poll(struct napi_stru
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(napi);
@@ -746,6 +844,7 @@ static void xcan_tx_interrupt(struct net
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);
}