Re: [PATCH net-next v8 1/8] net: dsa: Add tag handling for Hirschmann Hellcreek switches

[Vladimir Oltean <olteanv@gmail.com>]

On Tue, Nov 03, 2020 at 08:10:54AM +0100, Kurt Kanzenbach wrote:
> The Hirschmann Hellcreek TSN switches have a special tagging protocol for frames
> exchanged between the CPU port and the master interface. The format is a one
> byte trailer indicating the destination or origin port.
> 
> It's quite similar to the Micrel KSZ tagging. That's why the implementation is
> based on that code.
> 
> Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
> ---
> diff --git a/net/dsa/tag_hellcreek.c b/net/dsa/tag_hellcreek.c
> new file mode 100644
> index 000000000000..2061de06eafb
> --- /dev/null
> +++ b/net/dsa/tag_hellcreek.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling
> + *
> + * Copyright (C) 2019,2020 Linutronix GmbH
> + * Author Kurt Kanzenbach <kurt@linutronix.de>
> + *
> + * Based on tag_ksz.c.
> + */
> +
> +#include <linux/etherdevice.h>
> +#include <linux/list.h>
> +#include <linux/slab.h>

You probably don't need these includes any longer, but you don't have to
resend this series just to remove them, you could do that afterwards.

> +#include <net/dsa.h>
> +
> +#include "dsa_priv.h"
> +
> +#define HELLCREEK_TAG_LEN	1
> +
> +static struct sk_buff *hellcreek_xmit(struct sk_buff *skb,
> +				      struct net_device *dev)
> +{
> +	struct dsa_port *dp = dsa_slave_to_port(dev);
> +	u8 *tag;
> +
> +	/* Tag encoding */
> +	tag  = skb_put(skb, HELLCREEK_TAG_LEN);
> +	*tag = BIT(dp->index);
> +
> +	return skb;
> +}
> +
> +static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
> +				     struct net_device *dev,
> +				     struct packet_type *pt)
> +{
> +	/* Tag decoding */
> +	u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
> +	unsigned int port = tag[0] & 0x03;
> +
> +	skb->dev = dsa_master_find_slave(dev, 0, port);
> +	if (!skb->dev) {
> +		netdev_warn(dev, "Failed to get source port: %d\n", port);
> +		return NULL;
> +	}
> +
> +	pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN);
> +
> +	skb->offload_fwd_mark = true;
> +
> +	return skb;
> +}
> +
> +static const struct dsa_device_ops hellcreek_netdev_ops = {
> +	.name	  = "hellcreek",
> +	.proto	  = DSA_TAG_PROTO_HELLCREEK,
> +	.xmit	  = hellcreek_xmit,
> +	.rcv	  = hellcreek_rcv,
> +	.overhead = HELLCREEK_TAG_LEN,
> +	.tail_tag = true,
> +};
> +
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK);
> +
> +module_dsa_tag_driver(hellcreek_netdev_ops);
> -- 
> 2.20.1
> 

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>