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Miller" , Jakub Kicinski , Rob Herring , Heiner Kallweit , Russell King , Alvin =?utf-8?Q?=C5=A0ipraga?= , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next 4/6] net: dsa: tag_rtl8_4: add realtek 8 byte protocol 4 tag Message-ID: <20211012125045.kh73y2vgsl47aola@skbuf> References: <20211012123557.3547280-1-alvin@pqrs.dk> <20211012123557.3547280-5-alvin@pqrs.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211012123557.3547280-5-alvin@pqrs.dk> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 12, 2021 at 02:35:53PM +0200, Alvin Šipraga wrote: > From: Alvin Šipraga > > This commit implements a basic version of the 8 byte tag protocol used > in the Realtek RTL8365MB-VC unmanaged switch, which carries with it a > protocol version of 0x04. > > The implementation itself only handles the parsing of the EtherType > value and Realtek protocol version, together with the source or > destination port fields. The rest is left unimplemented for now. > > The tag format is described in a confidential document provided to my > company by Realtek Semiconductor Corp. Permission has been granted by > the vendor to publish this driver based on that material, together with > an extract from the document describing the tag format and its fields. > It is hoped that this will help future implementors who do not have > access to the material but who wish to extend the functionality of > drivers for chips which use this protocol. > > In addition, two possible values of the REASON field are specified, > based on experiments on my end. Realtek does not specify what value this > field can take. > > Signed-off-by: Alvin Šipraga > --- Reviewed-by: Vladimir Oltean > RFC -> v1: > - minor changes to the big comment at the top, including some > empirical information about the REASON code > - use dev_*_ratelimited() instead of netdev_*() for logging > - use warning instead of debug messages > - use ETH_P_REALTEK from if_ether.h > - set LEARN_DIS on xmit > - remove superfluous variables/expressions and use __b16 for tag > variable > - use new helper functions to insert/remove CPU tag > - set offload_fwd_mark properly using helper function > > include/net/dsa.h | 2 + > net/dsa/Kconfig | 6 ++ > net/dsa/Makefile | 1 + > net/dsa/tag_rtl8_4.c | 166 +++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 175 insertions(+) > create mode 100644 net/dsa/tag_rtl8_4.c > > diff --git a/include/net/dsa.h b/include/net/dsa.h > index d784e76113b8..783060e851a9 100644 > --- a/include/net/dsa.h > +++ b/include/net/dsa.h > @@ -51,6 +51,7 @@ struct phylink_link_state; > #define DSA_TAG_PROTO_SEVILLE_VALUE 21 > #define DSA_TAG_PROTO_BRCM_LEGACY_VALUE 22 > #define DSA_TAG_PROTO_SJA1110_VALUE 23 > +#define DSA_TAG_PROTO_RTL8_4_VALUE 24 > > enum dsa_tag_protocol { > DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE, > @@ -77,6 +78,7 @@ enum dsa_tag_protocol { > DSA_TAG_PROTO_OCELOT_8021Q = DSA_TAG_PROTO_OCELOT_8021Q_VALUE, > DSA_TAG_PROTO_SEVILLE = DSA_TAG_PROTO_SEVILLE_VALUE, > DSA_TAG_PROTO_SJA1110 = DSA_TAG_PROTO_SJA1110_VALUE, > + DSA_TAG_PROTO_RTL8_4 = DSA_TAG_PROTO_RTL8_4_VALUE, > }; > > struct dsa_switch; > diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig > index 6c7f79e45886..57fc52b17d55 100644 > --- a/net/dsa/Kconfig > +++ b/net/dsa/Kconfig > @@ -130,6 +130,12 @@ config NET_DSA_TAG_RTL4_A > Realtek switches with 4 byte protocol A tags, sich as found in > the Realtek RTL8366RB. > > +config NET_DSA_TAG_RTL8_4 > + tristate "Tag driver for Realtek 8 byte protocol 4 tags" > + help > + Say Y or M if you want to enable support for tagging frames for Realtek > + switches with 8 byte protocol 4 tags, such as the Realtek RTL8365MB-VC. > + > config NET_DSA_TAG_LAN9303 > tristate "Tag driver for SMSC/Microchip LAN9303 family of switches" > help > diff --git a/net/dsa/Makefile b/net/dsa/Makefile > index f78d537044db..9f75820e7c98 100644 > --- a/net/dsa/Makefile > +++ b/net/dsa/Makefile > @@ -16,6 +16,7 @@ obj-$(CONFIG_NET_DSA_TAG_OCELOT) += tag_ocelot.o > obj-$(CONFIG_NET_DSA_TAG_OCELOT_8021Q) += tag_ocelot_8021q.o > obj-$(CONFIG_NET_DSA_TAG_QCA) += tag_qca.o > obj-$(CONFIG_NET_DSA_TAG_RTL4_A) += tag_rtl4_a.o > +obj-$(CONFIG_NET_DSA_TAG_RTL8_4) += tag_rtl8_4.o > obj-$(CONFIG_NET_DSA_TAG_SJA1105) += tag_sja1105.o > obj-$(CONFIG_NET_DSA_TAG_TRAILER) += tag_trailer.o > obj-$(CONFIG_NET_DSA_TAG_XRS700X) += tag_xrs700x.o > diff --git a/net/dsa/tag_rtl8_4.c b/net/dsa/tag_rtl8_4.c > new file mode 100644 > index 000000000000..da22fd12b645 > --- /dev/null > +++ b/net/dsa/tag_rtl8_4.c > @@ -0,0 +1,166 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Handler for Realtek 8 byte switch tags > + * > + * Copyright (C) 2021 Alvin Šipraga > + * > + * NOTE: Currently only supports protocol "4" found in the RTL8365MB, hence > + * named tag_rtl8_4. > + * > + * This tag header has the following format: > + * > + * ------------------------------------------- > + * | MAC DA | MAC SA | 8 byte tag | Type | ... > + * ------------------------------------------- > + * _______________/ \______________________________________ > + * / \ > + * 0 7|8 15 > + * |-----------------------------------+-----------------------------------|--- > + * | (16-bit) | ^ > + * | Realtek EtherType [0x8899] | | > + * |-----------------------------------+-----------------------------------| 8 > + * | (8-bit) | (8-bit) | > + * | Protocol [0x04] | REASON | b > + * |-----------------------------------+-----------------------------------| y > + * | (1) | (1) | (2) | (1) | (3) | (1) | (1) | (1) | (5) | t > + * | FID_EN | X | FID | PRI_EN | PRI | KEEP | X | LEARN_DIS | X | e > + * |-----------------------------------+-----------------------------------| s After our previous discussion I thought you said these bits were an EFID_EN and EFID? Or did you reconsider? > + * | (1) | (15-bit) | | > + * | ALLOW | TX/RX | v > + * |-----------------------------------+-----------------------------------|--- > + * > + * With the following field descriptions: > + * > + * field | description > + * ------------+------------- > + * Realtek | 0x8899: indicates that this is a proprietary Realtek tag; > + * EtherType | note that Realtek uses the same EtherType for > + * | other incompatible tag formats (e.g. tag_rtl4_a.c) > + * Protocol | 0x04: indicates that this tag conforms to this format > + * X | reserved > + * ------------+------------- > + * REASON | reason for forwarding packet to CPU > + * | 0: packet was forwarded or flooded to CPU > + * | 80: packet was trapped to CPU > + * FID_EN | 1: packet has an FID > + * | 0: no FID > + * FID | FID of packet (if FID_EN=1) > + * PRI_EN | 1: force priority of packet > + * | 0: don't force priority > + * PRI | priority of packet (if PRI_EN=1) > + * KEEP | preserve packet VLAN tag format > + * LEARN_DIS | don't learn the source MAC address of the packet > + * ALLOW | 1: treat TX/RX field as an allowance port mask, meaning the > + * | packet may only be forwarded to ports specified in the > + * | mask > + * | 0: no allowance port mask, TX/RX field is the forwarding > + * | port mask > + * TX/RX | TX (switch->CPU): port number the packet was received on > + * | RX (CPU->switch): forwarding port mask (if ALLOW=0) > + * | allowance port mask (if ALLOW=1) > + */ > + > +#include > +#include > + > +#include "dsa_priv.h" > + > +#define RTL8_4_TAG_LEN 8 > +/* 0x04 = RTL8365MB DSA protocol > + */ > +#define RTL8_4_PROTOCOL_RTL8365MB 0x04 > + > +static struct sk_buff *rtl8_4_tag_xmit(struct sk_buff *skb, > + struct net_device *dev) > +{ > + struct dsa_port *dp = dsa_slave_to_port(dev); > + __be16 *tag; > + > + /* Pad out so the (stripped) packet is at least 64 bytes long > + * (including FCS), otherwise the switch will drop the packet. > + * Then we need an additional 8 bytes for the Realtek tag. > + */ > + if (unlikely(__skb_put_padto(skb, ETH_ZLEN + RTL8_4_TAG_LEN, false))) > + return NULL; > + > + skb_push(skb, RTL8_4_TAG_LEN); > + > + dsa_alloc_etype_header(skb, RTL8_4_TAG_LEN); > + tag = dsa_etype_header_pos_tx(skb); > + > + /* Set Realtek EtherType */ > + tag[0] = htons(ETH_P_REALTEK); > + > + /* Set Protocol; zero REASON */ > + tag[1] = htons(RTL8_4_PROTOCOL_RTL8365MB << 8); > + > + /* Zero FID_EN, FID, PRI_EN, PRI, KEEP; set LEARN_DIS */ > + tag[2] = htons(1 << 5); > + > + /* Zero ALLOW; set RX (CPU->switch) forwarding port mask */ > + tag[3] = htons(BIT(dp->index)); > + > + return skb; > +} > + > +static struct sk_buff *rtl8_4_tag_rcv(struct sk_buff *skb, > + struct net_device *dev) > +{ > + __be16 *tag; > + u16 etype; > + u8 proto; > + u8 port; > + > + if (unlikely(!pskb_may_pull(skb, RTL8_4_TAG_LEN))) > + return NULL; > + > + tag = dsa_etype_header_pos_rx(skb); > + > + /* Parse Realtek EtherType */ > + etype = ntohs(tag[0]); > + if (unlikely(etype != ETH_P_REALTEK)) { > + dev_warn_ratelimited(&dev->dev, > + "non-realtek ethertype 0x%04x\n", etype); > + return NULL; > + } > + > + /* Parse Protocol */ > + proto = ntohs(tag[1]) >> 8; > + if (unlikely(proto != RTL8_4_PROTOCOL_RTL8365MB)) { > + dev_warn_ratelimited(&dev->dev, > + "unknown realtek protocol 0x%02x\n", > + proto); > + return NULL; > + } > + > + /* Parse TX (switch->CPU) */ > + port = ntohs(tag[3]) & 0xf; /* Port number is the LSB 4 bits */ > + skb->dev = dsa_master_find_slave(dev, 0, port); > + if (!skb->dev) { > + dev_warn_ratelimited(&dev->dev, > + "could not find slave for port %d\n", > + port); > + return NULL; > + } > + > + /* Remove tag and recalculate checksum */ > + skb_pull_rcsum(skb, RTL8_4_TAG_LEN); > + > + dsa_strip_etype_header(skb, RTL8_4_TAG_LEN); > + > + dsa_default_offload_fwd_mark(skb); > + > + return skb; > +} > + > +static const struct dsa_device_ops rtl8_4_netdev_ops = { > + .name = "rtl8_4", > + .proto = DSA_TAG_PROTO_RTL8_4, > + .xmit = rtl8_4_tag_xmit, > + .rcv = rtl8_4_tag_rcv, > + .needed_headroom = RTL8_4_TAG_LEN, > +}; > +module_dsa_tag_driver(rtl8_4_netdev_ops); > + > +MODULE_LICENSE("GPL"); > +MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL8_4); > -- > 2.32.0 >