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Date:   Tue, 7 Jun 2022 12:13:21 +0200
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc:     linux-kernel@vger.kernel.org,
        Amarula patchwork <linux-amarula@amarulasolutions.com>,
        michael@amarulasolutions.com,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
        Wolfgang Grandegger <wg@grandegger.com>,
        linux-can@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [RFC PATCH 13/13] can: slcan: extend the protocol with CAN state
 info
Message-ID: <20220607101321.3uihcgpomplyjhhq@pengutronix.de>
References: <20220607094752.1029295-1-dario.binacchi@amarulasolutions.com>
 <20220607094752.1029295-14-dario.binacchi@amarulasolutions.com>
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On 07.06.2022 11:47:52, Dario Binacchi wrote:
> It extends the protocol to receive the adapter CAN state changes
> (warning, busoff, etc.) and forward them to the netdev upper levels.
>=20
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
>=20
> ---
>=20
>  drivers/net/can/slcan/slcan-core.c | 65 ++++++++++++++++++++++++++++++
>  1 file changed, 65 insertions(+)
>=20
> diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/s=
lcan-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 inter=
faces");
>  #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
> =20
>  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			 *
>    **********************************************************************=
**/
> =20
> +static void slc_bump_state(struct slcan *sl)
> +{
> +	struct net_device *dev =3D sl->dev;
> +	struct sk_buff *skb;
> +	struct can_frame *cf;
> +	char *cmd =3D sl->rbuff;
> +	u32 rxerr, txerr;
> +	enum can_state state, rx_state, tx_state;
> +
> +	if (*cmd !=3D 's')
> +		return;
> +
> +	cmd +=3D SLC_CMD_LEN;
> +	switch (*cmd) {
> +	case 'a':
> +		state =3D CAN_STATE_ERROR_ACTIVE;
> +		break;
> +	case 'w':
> +		state =3D CAN_STATE_ERROR_WARNING;
> +		break;
> +	case 'p':
> +		state =3D CAN_STATE_ERROR_PASSIVE;
> +		break;
> +	case 'f':
> +		state =3D CAN_STATE_BUS_OFF;
> +		break;
> +	default:
> +		return;
> +	}
> +
> +	if (state =3D=3D sl->can.state)
> +		return;
> +
> +	cmd +=3D SLC_STATE_BE_RXCNT_LEN + 1;
> +	cmd[SLC_STATE_BE_TXCNT_LEN] =3D 0;
> +	if (kstrtou32(cmd, 10, &txerr))
> +		return;
> +
> +	*cmd =3D 0;
> +	cmd -=3D SLC_STATE_BE_RXCNT_LEN;
> +	if (kstrtou32(cmd, 10, &rxerr))
> +		return;
> +
> +	skb =3D alloc_can_err_skb(dev, &cf);
> +	if (unlikely(!skb))
> +		return;

Please continue error handling, even if no skb can be allocated.

> +
> +	cf->data[6] =3D txerr;
> +	cf->data[7] =3D rxerr;
> +
> +	tx_state =3D txerr >=3D rxerr ? state : 0;
> +	rx_state =3D txerr <=3D rxerr ? state : 0;
> +	can_change_state(dev, cf, tx_state, rx_state);
> +
> +	if (state =3D=3D CAN_STATE_BUS_OFF)
> +		can_bus_off(dev);
> +
> +	netif_rx(skb);
> +}
> +
>  static void slc_bump_err(struct slcan *sl)
>  {
>  	struct net_device *dev =3D 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;
>  	}

Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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