can: pcan_usb: add support of rxerr/txerr counters

This patch adds the support of the rx/tx errors CAN counters to the
driver of the PCAN-USB PC-CAN interface from PEAK-System GmbH.

The PCAN-USB is capable of giving back the values of the rx/tx errors
counters, to provide more details and statistics to the linux-can layer.
Getting these values allows the driver to better tune CAN_ERR_CRTL_TX_xxx
and CAN_ERR_CRTL_RX_xxx bits in case of the interface enters any
CAN_STATE_ERROR_xxx state.

Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Link: https://lore.kernel.org/r/20191206153803.17725-3-s.grosjean@peak-system.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index 7646825..63bd2ed 100644 (file)
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c
@@ -41,6 +41,7 @@ MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB adapter");
 #define PCAN_USB_CMD_SN                6
 #define PCAN_USB_CMD_REGISTER  9
 #define PCAN_USB_CMD_EXT_VCC   10
+#define PCAN_USB_CMD_ERR_FR    11
 
 /* PCAN_USB_CMD_SET_BUS number arg */
 #define PCAN_USB_BUS_XCVER             2
@@ -82,6 +83,10 @@ MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB adapter");
 #define PCAN_USB_ERROR_QOVR            0x40
 #define PCAN_USB_ERROR_TXQFULL         0x80
 
+#define PCAN_USB_ERROR_BUS             (PCAN_USB_ERROR_BUS_LIGHT | \
+                                        PCAN_USB_ERROR_BUS_HEAVY | \
+                                        PCAN_USB_ERROR_BUS_OFF)
+
 /* SJA1000 modes */
 #define SJA1000_MODE_NORMAL            0x00
 #define SJA1000_MODE_INIT              0x01
@@ -101,11 +106,25 @@ MODULE_SUPPORTED_DEVICE("PEAK-System PCAN-USB adapter");
 #define PCAN_USB_REC_TS                        4
 #define PCAN_USB_REC_BUSEVT            5
 
+/* CAN bus events notifications selection mask */
+#define PCAN_USB_ERR_RXERR             0x02    /* ask for rxerr counter */
+#define PCAN_USB_ERR_TXERR             0x04    /* ask for txerr counter */
+
+/* This mask generates an usb packet each time the state of the bus changes.
+ * 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)
+
+/* identify bus event packets with rx/tx error counters */
+#define PCAN_USB_ERR_CNT               0x80
+
 /* private to PCAN-USB adapter */
 struct pcan_usb {
        struct peak_usb_device dev;
        struct peak_time_ref time_ref;
        struct timer_list restart_timer;
+       struct can_berr_counter bec;
 };
 
 /* incoming message context for decoding */
@@ -212,6 +231,16 @@ static int pcan_usb_set_silent(struct peak_usb_device *dev, u8 onoff)
                                 PCAN_USB_BUS_SILENT_MODE, args);
 }
 
+/* send the cmd to be notified from bus errors */
+static int pcan_usb_set_err_frame(struct peak_usb_device *dev, u8 err_mask)
+{
+       u8 args[PCAN_USB_CMD_ARGS_LEN] = {
+               [0] = err_mask,
+       };
+
+       return pcan_usb_send_cmd(dev, PCAN_USB_CMD_ERR_FR, PCAN_USB_SET, args);
+}
+
 static int pcan_usb_set_ext_vcc(struct peak_usb_device *dev, u8 onoff)
 {
        u8 args[PCAN_USB_CMD_ARGS_LEN] = {
@@ -445,7 +474,7 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
                        new_state = CAN_STATE_BUS_OFF;
                        break;
                }
-               if (n & (PCAN_USB_ERROR_RXQOVR | PCAN_USB_ERROR_QOVR)) {
+               if (n & ~PCAN_USB_ERROR_BUS) {
                        /*
                         * trick to bypass next comparison and process other
                         * errors
@@ -469,7 +498,7 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
                        new_state = CAN_STATE_ERROR_WARNING;
                        break;
                }
-               if (n & (PCAN_USB_ERROR_RXQOVR | PCAN_USB_ERROR_QOVR)) {
+               if (n & ~PCAN_USB_ERROR_BUS) {
                        /*
                         * trick to bypass next comparison and process other
                         * errors
@@ -508,29 +537,50 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
 
        case CAN_STATE_ERROR_PASSIVE:
                cf->can_id |= CAN_ERR_CRTL;
-               cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE |
-                              CAN_ERR_CRTL_RX_PASSIVE;
+               cf->data[1] = (mc->pdev->bec.txerr > mc->pdev->bec.rxerr) ?
+                               CAN_ERR_CRTL_TX_PASSIVE :
+                               CAN_ERR_CRTL_RX_PASSIVE;
+               cf->data[6] = mc->pdev->bec.txerr;
+               cf->data[7] = mc->pdev->bec.rxerr;
+
                mc->pdev->dev.can.can_stats.error_passive++;
                break;
 
        case CAN_STATE_ERROR_WARNING:
                cf->can_id |= CAN_ERR_CRTL;
-               cf->data[1] |= CAN_ERR_CRTL_TX_WARNING |
-                              CAN_ERR_CRTL_RX_WARNING;
+               cf->data[1] = (mc->pdev->bec.txerr > mc->pdev->bec.rxerr) ?
+                               CAN_ERR_CRTL_TX_WARNING :
+                               CAN_ERR_CRTL_RX_WARNING;
+               cf->data[6] = mc->pdev->bec.txerr;
+               cf->data[7] = mc->pdev->bec.rxerr;
+
                mc->pdev->dev.can.can_stats.error_warning++;
                break;
 
        case CAN_STATE_ERROR_ACTIVE:
                cf->can_id |= CAN_ERR_CRTL;
                cf->data[1] = CAN_ERR_CRTL_ACTIVE;
+
+               /* sync local copies of rxerr/txerr counters */
+               mc->pdev->bec.txerr = 0;
+               mc->pdev->bec.rxerr = 0;
                break;
 
        default:
                /* CAN_STATE_MAX (trick to handle other errors) */
-               cf->can_id |= CAN_ERR_CRTL;
-               cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
-               mc->netdev->stats.rx_over_errors++;
-               mc->netdev->stats.rx_errors++;
+               if (n & PCAN_USB_ERROR_TXQFULL)
+                       netdev_dbg(mc->netdev, "device Tx queue full)\n");
+
+               if (n & PCAN_USB_ERROR_RXQOVR) {
+                       netdev_dbg(mc->netdev, "data overrun interrupt\n");
+                       cf->can_id |= CAN_ERR_CRTL;
+                       cf->data[1] |= CAN_ERR_CRTL_RX_OVERFLOW;
+                       mc->netdev->stats.rx_over_errors++;
+                       mc->netdev->stats.rx_errors++;
+               }
+
+               cf->data[6] = mc->pdev->bec.txerr;
+               cf->data[7] = mc->pdev->bec.rxerr;
 
                new_state = mc->pdev->dev.can.state;
                break;
@@ -552,6 +602,30 @@ static int pcan_usb_decode_error(struct pcan_usb_msg_context *mc, u8 n,
        return 0;
 }
 
+/* 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)
+{
+       struct pcan_usb *pdev = mc->pdev;
+
+       /* acccording to the content of the packet */
+       switch (ir) {
+       case PCAN_USB_ERR_CNT:
+
+               /* save rx/tx error counters from in the device context */
+               pdev->bec.rxerr = mc->ptr[0];
+               pdev->bec.txerr = mc->ptr[1];
+               break;
+
+       default:
+               /* reserved */
+               break;
+       }
+
+       return 0;
+}
+
 /*
  * decode non-data usb message
  */
@@ -606,9 +680,10 @@ static int pcan_usb_decode_status(struct pcan_usb_msg_context *mc,
                break;
 
        case PCAN_USB_REC_BUSEVT:
-               /* error frame/bus event */
-               if (n & PCAN_USB_ERROR_TXQFULL)
-                       netdev_dbg(mc->netdev, "device Tx queue full)\n");
+               /* bus event notifications (get rxerr/txerr) */
+               err = pcan_usb_handle_bus_evt(mc, n);
+               if (err)
+                       return err;
                break;
        default:
                netdev_err(mc->netdev, "unexpected function %u\n", f);
@@ -792,20 +867,44 @@ static int pcan_usb_encode_msg(struct peak_usb_device *dev, struct sk_buff *skb,
        return 0;
 }
 
+/* socket callback used to copy berr counters values received through USB */
+static int pcan_usb_get_berr_counter(const struct net_device *netdev,
+                                    struct can_berr_counter *bec)
+{
+       struct peak_usb_device *dev = netdev_priv(netdev);
+       struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);
+
+       *bec = pdev->bec;
+
+       /* must return 0 */
+       return 0;
+}
+
 /*
  * start interface
  */
 static int pcan_usb_start(struct peak_usb_device *dev)
 {
        struct pcan_usb *pdev = container_of(dev, struct pcan_usb, dev);
+       int err;
 
        /* number of bits used in timestamps read from adapter struct */
        peak_usb_init_time_ref(&pdev->time_ref, &pcan_usb);
 
+       pdev->bec.rxerr = 0;
+       pdev->bec.txerr = 0;
+
+       /* be notified on error counter changes (if requested by user) */
+       if (dev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) {
+               err = pcan_usb_set_err_frame(dev, PCAN_USB_BERR_MASK);
+               if (err)
+                       netdev_warn(dev->netdev,
+                                   "Asking for BERR reporting error %u\n",
+                                   err);
+       }
+
        /* if revision greater than 3, can put silent mode on/off */
        if (dev->device_rev > 3) {
-               int err;
-
                err = pcan_usb_set_silent(dev,
                                dev->can.ctrlmode & CAN_CTRLMODE_LISTENONLY);
                if (err)
@@ -892,7 +991,8 @@ const struct peak_usb_adapter pcan_usb = {
        .name = "PCAN-USB",
        .device_id = PCAN_USB_PRODUCT_ID,
        .ctrl_count = 1,
-       .ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY,
+       .ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES | CAN_CTRLMODE_LISTENONLY |
+                             CAN_CTRLMODE_BERR_REPORTING,
        .clock = {
                .freq = PCAN_USB_CRYSTAL_HZ / 2 ,
        },
@@ -925,4 +1025,5 @@ const struct peak_usb_adapter pcan_usb = {
        .dev_encode_msg = pcan_usb_encode_msg,
        .dev_start = pcan_usb_start,
        .dev_restart_async = pcan_usb_restart_async,
+       .do_get_berr_counter = pcan_usb_get_berr_counter,
 };