[RFC PATCH 13/13] can: slcan: extend the protocol with CAN state info

[Dario Binacchi <dario.binacchi@amarulasolutions.com>]

It extends the protocol to receive the adapter CAN state changes
(warning, busoff, etc.) and forward them to the netdev upper levels.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>

---

 drivers/net/can/slcan/slcan-core.c | 65 ++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index 02e7c14de45c..ab4c08a7dc81 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -78,6 +78,9 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
 #define SLC_CMD_LEN 1
 #define SLC_SFF_ID_LEN 3
 #define SLC_EFF_ID_LEN 8
+#define SLC_STATE_LEN 1
+#define SLC_STATE_BE_RXCNT_LEN 3
+#define SLC_STATE_BE_TXCNT_LEN 3
 
 struct slcan {
 	struct can_priv         can;
@@ -182,6 +185,66 @@ int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on)
   *			STANDARD SLCAN DECAPSULATION			 *
   ************************************************************************/
 
+static void slc_bump_state(struct slcan *sl)
+{
+	struct net_device *dev = sl->dev;
+	struct sk_buff *skb;
+	struct can_frame *cf;
+	char *cmd = sl->rbuff;
+	u32 rxerr, txerr;
+	enum can_state state, rx_state, tx_state;
+
+	if (*cmd != 's')
+		return;
+
+	cmd += SLC_CMD_LEN;
+	switch (*cmd) {
+	case 'a':
+		state = CAN_STATE_ERROR_ACTIVE;
+		break;
+	case 'w':
+		state = CAN_STATE_ERROR_WARNING;
+		break;
+	case 'p':
+		state = CAN_STATE_ERROR_PASSIVE;
+		break;
+	case 'f':
+		state = CAN_STATE_BUS_OFF;
+		break;
+	default:
+		return;
+	}
+
+	if (state == sl->can.state)
+		return;
+
+	cmd += SLC_STATE_BE_RXCNT_LEN + 1;
+	cmd[SLC_STATE_BE_TXCNT_LEN] = 0;
+	if (kstrtou32(cmd, 10, &txerr))
+		return;
+
+	*cmd = 0;
+	cmd -= SLC_STATE_BE_RXCNT_LEN;
+	if (kstrtou32(cmd, 10, &rxerr))
+		return;
+
+	skb = alloc_can_err_skb(dev, &cf);
+	if (unlikely(!skb))
+		return;
+
+	cf->data[6] = txerr;
+	cf->data[7] = rxerr;
+
+	tx_state = txerr >= rxerr ? state : 0;
+	rx_state = txerr <= rxerr ? state : 0;
+	can_change_state(dev, cf, tx_state, rx_state);
+
+	if (state == CAN_STATE_BUS_OFF)
+		can_bus_off(dev);
+
+	netif_rx(skb);
+}
+
 static void slc_bump_err(struct slcan *sl)
 {
 	struct net_device *dev = sl->dev;
@@ -354,6 +417,8 @@ static void slc_bump(struct slcan *sl)
 		return slc_bump_frame(sl);
 	case 'e':
 		return slc_bump_err(sl);
+	case 's':
+		return slc_bump_state(sl);
 	default:
 		return;
 	}
-- 
2.32.0