| From 86dd9868b8788a9063893a97649594af93cd5aa6 Mon Sep 17 00:00:00 2001 |
| From: Linus Walleij <linus.walleij@linaro.org> |
| Date: Wed, 17 Feb 2021 00:55:42 +0100 |
| Subject: net: dsa: tag_rtl4_a: Support also egress tags |
| |
| From: Linus Walleij <linus.walleij@linaro.org> |
| |
| commit 86dd9868b8788a9063893a97649594af93cd5aa6 upstream. |
| |
| Support also transmitting frames using the custom "8899 A" |
| 4 byte tag. |
| |
| Qingfang came up with the solution: we need to pad the |
| ethernet frame to 60 bytes using eth_skb_pad(), then the |
| switch will happily accept frames with custom tags. |
| |
| Cc: Mauri Sandberg <sandberg@mailfence.com> |
| Reported-by: DENG Qingfang <dqfext@gmail.com> |
| Fixes: efd7fe68f0c6 ("net: dsa: tag_rtl4_a: Implement Realtek 4 byte A tag") |
| Signed-off-by: Linus Walleij <linus.walleij@linaro.org> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/dsa/tag_rtl4_a.c | 43 +++++++++++++++++++++++++++++-------------- |
| 1 file changed, 29 insertions(+), 14 deletions(-) |
| |
| --- a/net/dsa/tag_rtl4_a.c |
| +++ b/net/dsa/tag_rtl4_a.c |
| @@ -12,9 +12,7 @@ |
| * |
| * The 2 bytes tag form a 16 bit big endian word. The exact |
| * meaning has been guessed from packet dumps from ingress |
| - * frames, as no working egress traffic has been available |
| - * we do not know the format of the egress tags or if they |
| - * are even supported. |
| + * frames. |
| */ |
| |
| #include <linux/etherdevice.h> |
| @@ -36,17 +34,34 @@ |
| static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb, |
| struct net_device *dev) |
| { |
| - /* |
| - * Just let it pass thru, we don't know if it is possible |
| - * to tag a frame with the 0x8899 ethertype and direct it |
| - * to a specific port, all attempts at reverse-engineering have |
| - * ended up with the frames getting dropped. |
| - * |
| - * The VLAN set-up needs to restrict the frames to the right port. |
| - * |
| - * If you have documentation on the tagging format for RTL8366RB |
| - * (tag type A) then please contribute. |
| - */ |
| + struct dsa_port *dp = dsa_slave_to_port(dev); |
| + u8 *tag; |
| + u16 *p; |
| + u16 out; |
| + |
| + /* Pad out to at least 60 bytes */ |
| + if (unlikely(eth_skb_pad(skb))) |
| + return NULL; |
| + if (skb_cow_head(skb, RTL4_A_HDR_LEN) < 0) |
| + return NULL; |
| + |
| + netdev_dbg(dev, "add realtek tag to package to port %d\n", |
| + dp->index); |
| + skb_push(skb, RTL4_A_HDR_LEN); |
| + |
| + memmove(skb->data, skb->data + RTL4_A_HDR_LEN, 2 * ETH_ALEN); |
| + tag = skb->data + 2 * ETH_ALEN; |
| + |
| + /* Set Ethertype */ |
| + p = (u16 *)tag; |
| + *p = htons(RTL4_A_ETHERTYPE); |
| + |
| + out = (RTL4_A_PROTOCOL_RTL8366RB << 12) | (2 << 8); |
| + /* The lower bits is the port numer */ |
| + out |= (u8)dp->index; |
| + p = (u16 *)(tag + 2); |
| + *p = htons(out); |
| + |
| return skb; |
| } |
| |