linux-kernel - [PATCH v2 13/13] can: slcan: extend the protocol with CAN state info

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Date:   Wed,  8 Jun 2022 18:51:16 +0200
From:   Dario Binacchi <dario.binacchi@...rulasolutions.com>
To:     linux-kernel@...r.kernel.org
Cc:     Amarula patchwork <linux-amarula@...rulasolutions.com>,
        michael@...rulasolutions.com,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Paolo Abeni <pabeni@...hat.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v2 13/13] can: slcan: extend the protocol with CAN state info

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@...rulasolutions.com>

---

Changes in v2:
- Continue error handling even if no skb can be allocated.

 drivers/net/can/slcan/slcan-core.c | 66 ++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index aba42e284274..22a261f2477c 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;
@@ -170,6 +173,67 @@ 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 (skb) {
+		cf->data[6] = txerr;
+		cf->data[7] = rxerr;
+	}
+
+	tx_state = txerr >= rxerr ? state : 0;
+	rx_state = txerr <= rxerr ? state : 0;
+	can_change_state(dev, skb ? cf : NULL, tx_state, rx_state);
+
+	if (state == CAN_STATE_BUS_OFF)
+		can_bus_off(dev);
+
+	if (skb)
+		netif_rx(skb);
+}
+
 static void slc_bump_err(struct slcan *sl)
 {
 	struct net_device *dev = sl->dev;
@@ -372,6 +436,8 @@ 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