[PATCH v3] can: peak_usb: Add PCAN-USB bus errors reporting
From: Stéphane Grosjean
Date: Fri Sep 25 2026 - 09:24:12 EST
From: Stéphane Grosjean <s.grosjean@xxxxxxxxxxxxxx>
The good old PCAN-USB was missing CAN bus error reporting. This patch fixes
that.
Signed-off-by: Stéphane Grosjean <s.grosjean@xxxxxxxxxxxxxx>
---
Changes in v3:
- Remove PCAN_USB_ERR_CNT_* constants and their erroneous comment
- Rework error counter handling
- Fix out-of-bounds check
- Link to v2: https://patch.msgid.link/20260925-peak_usb-v2-1-f3257bdeb7e6@xxxxxxxxxxxxxx
Changes in v2:
- Remove legacy bus error handling code
- Fix potential out-of-bounds read in pcan_usb_handle_bus_evt()
- Link to v1: https://patch.msgid.link/20260924-peak_usb-v1-1-d48875169a59@xxxxxxxxxxxxxx
To: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
To: Vincent Mailhol <mailhol@xxxxxxxxxx>
Cc: linux-can@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/net/can/usb/peak_usb/pcan_usb.c | 116 +++++++++++++++++++++++++++-----
1 file changed, 99 insertions(+), 17 deletions(-)
diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index 8fd058c32856..c59166a29648 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c
@@ -115,6 +115,7 @@
#define PCAN_USB_REC_BUSEVT 5
/* CAN bus events notifications selection mask */
+#define PCAN_USB_ERR_ECC 0x01 /* ask for BERR */
#define PCAN_USB_ERR_RXERR 0x02 /* ask for rxerr counter */
#define PCAN_USB_ERR_TXERR 0x04 /* ask for txerr counter */
@@ -122,11 +123,20 @@
* In other words, its interest is to know which side among rx and tx is
* responsible of the change of the bus state.
*/
-#define PCAN_USB_BERR_MASK (PCAN_USB_ERR_RXERR | PCAN_USB_ERR_TXERR)
+#define PCAN_USB_BERR_MASK (PCAN_USB_ERR_ECC | \
+ PCAN_USB_ERR_RXERR | PCAN_USB_ERR_TXERR)
-/* identify bus event packets with rx/tx error counters */
-#define PCAN_USB_ERR_CNT_DEC 0x00 /* counters are decreasing */
-#define PCAN_USB_ERR_CNT_INC 0x80 /* counters are increasing */
+/* SJA1000 ECC register */
+#define PCAN_SJA1000_ECC_SEG 0x1f
+#define PCAN_SJA1000_ECC_DIR 0x20
+#define PCAN_SJA1000_ECC_ERR 6
+#define PCAN_SJA1000_ECC_BIT 0x00
+#define PCAN_SJA1000_ECC_FORM 0x40
+#define PCAN_SJA1000_ECC_STUFF 0x80
+#define PCAN_SJA1000_ECC_MASK 0xc0
+
+/* SJA1000 Bus Error Interrupt */
+#define PCAN_SJA1000_IRQ_BEI 0x80
/* private to PCAN-USB adapter */
struct pcan_usb {
@@ -550,23 +560,94 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
/* decode bus event usb packet: first byte contains rxerr while 2nd one contains
* txerr.
*/
-static int pcan_usb_handle_bus_evt(struct pcan_usb_msg_context *mc, u8 ir)
+static int pcan_usb_handle_bus_evt(struct pcan_usb_msg_context *mc, u8 ir,
+ u8 status_len)
{
struct pcan_usb *pdev = mc->pdev;
+ u8 rec_len = status_len & PCAN_USB_STATUSLEN_DLC;
- /* according to the content of the packet */
- switch (ir) {
- case PCAN_USB_ERR_CNT_DEC:
- case PCAN_USB_ERR_CNT_INC:
+ /* Check for potential out-of-bound accesses
+ * ("end" is a misnomer; it is not a pointer to the last valid byte,
+ * but rather to the one following it)
+ */
+ if (!rec_len || (mc->ptr + rec_len) > mc->end)
+ return -EINVAL;
- /* save rx/tx error counters from in the device context */
+ /* 1st byte is ECC (if BEI), 2nd one is rxerr, 3rd one is txerr:
+ * save rx/tx error counters from record data bytes first, so that
+ * device error counters are always up-to-date.
+ */
+ if (rec_len > 1) {
pdev->bec.rxerr = mc->ptr[1];
- pdev->bec.txerr = mc->ptr[2];
- break;
+ if (rec_len > 2)
+ pdev->bec.txerr = mc->ptr[2];
+ }
- default:
- /* reserved */
- break;
+ /* Then process bus error interrupt (if any) */
+ if (ir & PCAN_SJA1000_IRQ_BEI) {
+ u8 ecc = mc->ptr[0];
+
+ /* create a "bus-error frame" skb if any bit is set in ECC */
+ if (ecc) {
+ struct net_device_stats *stats = &mc->netdev->stats;
+ struct sk_buff *skb;
+ struct can_frame *cf;
+ u8 can_err_tx = 0;
+
+ pdev->dev.can.can_stats.bus_error++;
+
+ /* Error occurred during reception? */
+ if (ecc & PCAN_SJA1000_ECC_DIR) {
+ stats->rx_errors++;
+ } else {
+ stats->tx_errors++;
+ can_err_tx = CAN_ERR_PROT_TX;
+ }
+
+ /* if berr-reporting is off, stop here */
+ if (!(pdev->dev.can.ctrlmode &
+ CAN_CTRLMODE_BERR_REPORTING))
+ return 0;
+
+ /* allocate an skb to store the error frame */
+ skb = alloc_can_err_skb(mc->netdev, &cf);
+ if (!skb)
+ return -ENOMEM;
+
+ cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+ cf->data[2] |= can_err_tx;
+
+ /* set error type according to 1st data byte (ECC) */
+ switch (ecc & PCAN_SJA1000_ECC_MASK) {
+ case PCAN_SJA1000_ECC_BIT:
+ cf->data[2] |= CAN_ERR_PROT_BIT;
+ break;
+ case PCAN_SJA1000_ECC_FORM:
+ cf->data[2] |= CAN_ERR_PROT_FORM;
+ break;
+ case PCAN_SJA1000_ECC_STUFF:
+ cf->data[2] |= CAN_ERR_PROT_STUFF;
+ break;
+ default:
+ break;
+ }
+
+ /* set error location */
+ cf->data[3] = ecc & PCAN_SJA1000_ECC_SEG;
+
+ cf->data[6] = pdev->bec.txerr;
+ cf->data[7] = pdev->bec.rxerr;
+
+ if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) {
+ struct skb_shared_hwtstamps *hwts =
+ skb_hwtstamps(skb);
+
+ peak_usb_get_ts_time(&mc->pdev->time_ref,
+ mc->ts16, &hwts->hwtstamp);
+ }
+
+ netif_rx(skb);
+ }
}
return 0;
@@ -627,7 +708,7 @@ static int pcan_usb_decode_status(struct pcan_usb_msg_context *mc,
case PCAN_USB_REC_BUSEVT:
/* bus event notifications (get rxerr/txerr) */
- err = pcan_usb_handle_bus_evt(mc, n);
+ err = pcan_usb_handle_bus_evt(mc, n, status_len);
if (err)
return err;
break;
@@ -1017,7 +1098,8 @@ const struct peak_usb_adapter pcan_usb = {
.device_id = PCAN_USB_PRODUCT_ID,
.ctrl_count = 1,
.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
- CAN_CTRLMODE_CC_LEN8_DLC,
+ CAN_CTRLMODE_CC_LEN8_DLC |
+ CAN_CTRLMODE_BERR_REPORTING,
.clock = {
.freq = PCAN_USB_CRYSTAL_HZ / 2,
},
---
base-commit: 3bb1277609aae9b56b8e9462fe18fc000944fa96
change-id: 20260924-peak_usb-5d8607af1f99
Best regards,
--
Stéphane Grosjean <s.grosjean@xxxxxxxxxxxxxx>