Consolidate and unify state change handling

index 02492d2..d238b68 100644
@@ -273,6 +273,85 @@ static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
     return err;
 }
 
+enum can_err_dir can_get_err_dir(unsigned int txerr, unsigned int rxerr)
+{
+    if (txerr > rxerr)
+        return CAN_ERR_DIR_TX;
+
+    if (txerr < rxerr)
+        return CAN_ERR_DIR_RX;
+
+    return CAN_ERR_DIR_UNKNOWN;
+}
+EXPORT_SYMBOL_GPL(can_get_err_dir);
+
+static int can_make_state_warning(enum can_err_dir err_dir)
+{
+    switch (err_dir) {
+    case CAN_ERR_DIR_TX:
+        return CAN_ERR_CRTL_TX_WARNING;
+    case CAN_ERR_DIR_RX:
+        return CAN_ERR_CRTL_RX_WARNING;
+    default:
+        return CAN_ERR_CRTL_TX_WARNING | CAN_ERR_CRTL_RX_WARNING;
+    }
+}
+
+static int can_make_state_passive(enum can_err_dir err_dir)
+{
+    switch (err_dir) {
+    case CAN_ERR_DIR_TX:
+        return CAN_ERR_CRTL_TX_PASSIVE;
+    case CAN_ERR_DIR_RX:
+        return CAN_ERR_CRTL_RX_PASSIVE;
+    default:
+        return CAN_ERR_CRTL_TX_PASSIVE | CAN_ERR_CRTL_RX_PASSIVE;
+    }
+}
+
+void can_change_state(struct net_device *dev, struct can_frame *cf,
+              enum can_state state, enum can_err_dir err_dir)
+{
+    struct can_priv *priv = netdev_priv(dev);
+
+    if (unlikely(state == priv->state)) {
+        netdev_warn(dev, "%s: oops, state did not change", __func__);
+        return;
+    }
+
+    if (state != CAN_STATE_BUS_OFF)
+        cf->can_id |= CAN_ERR_CRTL;
+
+    switch (state) {
+    case CAN_STATE_ERROR_WARNING:
+        if (state > priv->state)
+            priv->can_stats.error_warning++;
+        cf->data[1] = can_make_state_warning(err_dir);
+        break;
+
+    case CAN_STATE_ERROR_PASSIVE:
+        if (state > priv->state)
+            priv->can_stats.error_passive++;
+        cf->data[1] = can_make_state_passive(err_dir);
+        break;
+
+    case CAN_STATE_ERROR_ACTIVE:
+        cf->data[1] = CAN_ERR_CRTL_ACTIVE;
+        break;
+
+    case CAN_STATE_BUS_OFF:
+        priv->can_stats.bus_off++;
+        cf->can_id |= CAN_ERR_BUSOFF;
+        break;
+
+    default:
+        break;
+    };
+
+    priv->state = state;
+}
+EXPORT_SYMBOL_GPL(can_change_state);
+
 /*
  * Local echo of CAN messages
  *

index 6992afc..9ef20fe 100644
@@ -27,6 +27,12 @@ enum can_mode {
     CAN_MODE_SLEEP
 };
 
+enum can_err_dir {
+    CAN_ERR_DIR_UNKNOWN = 0,
+    CAN_ERR_DIR_RX,
+    CAN_ERR_DIR_TX
+};
+
 /*
  * CAN common private data
  */

@@ -121,6 +127,10 @@ void unregister_candev(struct net_device *dev);
 int can_restart_now(struct net_device *dev);
 void can_bus_off(struct net_device *dev);
 
+enum can_err_dir can_get_err_dir(unsigned int txerr, unsigned int rxerr);
+void can_change_state(struct net_device *dev, struct can_frame *cf,
+        enum can_state state, enum can_err_dir err_dir);
+
 void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
               unsigned int idx);
 unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx);

index c247446..1c508be 100644
@@ -71,6 +71,7 @@
 #define CAN_ERR_CRTL_TX_PASSIVE  0x20 /* reached error passive status