diff options
Diffstat (limited to 'net/dsa/tag_rtl8_4.c')
| -rw-r--r-- | net/dsa/tag_rtl8_4.c | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/net/dsa/tag_rtl8_4.c b/net/dsa/tag_rtl8_4.c new file mode 100644 index 000000000000..a593ead7ff26 --- /dev/null +++ b/net/dsa/tag_rtl8_4.c @@ -0,0 +1,258 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Handler for Realtek 8 byte switch tags + * + * Copyright (C) 2021 Alvin Šipraga <alsi@bang-olufsen.dk> + * + * NOTE: Currently only supports protocol "4" found in the RTL8365MB, hence + * named tag_rtl8_4. + * + * This tag has the following format: + * + * 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 + * | (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) + * + * The tag can be positioned before Ethertype, using tag "rtl8_4": + * + * +--------+--------+------------+------+----- + * | MAC DA | MAC SA | 8 byte tag | Type | ... + * +--------+--------+------------+------+----- + * + * The tag can also appear between the end of the payload and before the CRC, + * using tag "rtl8_4t": + * + * +--------+--------+------+-----+---------+------------+-----+ + * | MAC DA | MAC SA | TYPE | ... | payload | 8-byte tag | CRC | + * +--------+--------+------+-----+---------+------------+-----+ + * + * The added bytes after the payload will break most checksums, either in + * software or hardware. To avoid this issue, if the checksum is still pending, + * this tagger checksums the packet in software before adding the tag. + * + */ + +#include <linux/bitfield.h> +#include <linux/bits.h> +#include <linux/etherdevice.h> + +#include "dsa_priv.h" + +/* Protocols supported: + * + * 0x04 = RTL8365MB DSA protocol + */ + +#define RTL8_4_TAG_LEN 8 + +#define RTL8_4_PROTOCOL GENMASK(15, 8) +#define RTL8_4_PROTOCOL_RTL8365MB 0x04 +#define RTL8_4_REASON GENMASK(7, 0) +#define RTL8_4_REASON_FORWARD 0 +#define RTL8_4_REASON_TRAP 80 + +#define RTL8_4_LEARN_DIS BIT(5) + +#define RTL8_4_TX GENMASK(3, 0) +#define RTL8_4_RX GENMASK(10, 0) + +static void rtl8_4_write_tag(struct sk_buff *skb, struct net_device *dev, + void *tag) +{ + struct dsa_port *dp = dsa_slave_to_port(dev); + __be16 tag16[RTL8_4_TAG_LEN / 2]; + + /* Set Realtek EtherType */ + tag16[0] = htons(ETH_P_REALTEK); + + /* Set Protocol; zero REASON */ + tag16[1] = htons(FIELD_PREP(RTL8_4_PROTOCOL, RTL8_4_PROTOCOL_RTL8365MB)); + + /* Zero FID_EN, FID, PRI_EN, PRI, KEEP; set LEARN_DIS */ + tag16[2] = htons(FIELD_PREP(RTL8_4_LEARN_DIS, 1)); + + /* Zero ALLOW; set RX (CPU->switch) forwarding port mask */ + tag16[3] = htons(FIELD_PREP(RTL8_4_RX, BIT(dp->index))); + + memcpy(tag, tag16, RTL8_4_TAG_LEN); +} + +static struct sk_buff *rtl8_4_tag_xmit(struct sk_buff *skb, + struct net_device *dev) +{ + skb_push(skb, RTL8_4_TAG_LEN); + + dsa_alloc_etype_header(skb, RTL8_4_TAG_LEN); + + rtl8_4_write_tag(skb, dev, dsa_etype_header_pos_tx(skb)); + + return skb; +} + +static struct sk_buff *rtl8_4t_tag_xmit(struct sk_buff *skb, + struct net_device *dev) +{ + /* Calculate the checksum here if not done yet as trailing tags will + * break either software or hardware based checksum + */ + if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb)) + return NULL; + + rtl8_4_write_tag(skb, dev, skb_put(skb, RTL8_4_TAG_LEN)); + + return skb; +} + +static int rtl8_4_read_tag(struct sk_buff *skb, struct net_device *dev, + void *tag) +{ + __be16 tag16[RTL8_4_TAG_LEN / 2]; + u16 etype; + u8 reason; + u8 proto; + u8 port; + + memcpy(tag16, tag, RTL8_4_TAG_LEN); + + /* Parse Realtek EtherType */ + etype = ntohs(tag16[0]); + if (unlikely(etype != ETH_P_REALTEK)) { + dev_warn_ratelimited(&dev->dev, + "non-realtek ethertype 0x%04x\n", etype); + return -EPROTO; + } + + /* Parse Protocol */ + proto = FIELD_GET(RTL8_4_PROTOCOL, ntohs(tag16[1])); + if (unlikely(proto != RTL8_4_PROTOCOL_RTL8365MB)) { + dev_warn_ratelimited(&dev->dev, + "unknown realtek protocol 0x%02x\n", + proto); + return -EPROTO; + } + + /* Parse REASON */ + reason = FIELD_GET(RTL8_4_REASON, ntohs(tag16[1])); + + /* Parse TX (switch->CPU) */ + port = FIELD_GET(RTL8_4_TX, ntohs(tag16[3])); + 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 -ENOENT; + } + + if (reason != RTL8_4_REASON_TRAP) + dsa_default_offload_fwd_mark(skb); + + return 0; +} + +static struct sk_buff *rtl8_4_tag_rcv(struct sk_buff *skb, + struct net_device *dev) +{ + if (unlikely(!pskb_may_pull(skb, RTL8_4_TAG_LEN))) + return NULL; + + if (unlikely(rtl8_4_read_tag(skb, dev, dsa_etype_header_pos_rx(skb)))) + return NULL; + + /* Remove tag and recalculate checksum */ + skb_pull_rcsum(skb, RTL8_4_TAG_LEN); + + dsa_strip_etype_header(skb, RTL8_4_TAG_LEN); + + return skb; +} + +static struct sk_buff *rtl8_4t_tag_rcv(struct sk_buff *skb, + struct net_device *dev) +{ + if (skb_linearize(skb)) + return NULL; + + if (unlikely(rtl8_4_read_tag(skb, dev, skb_tail_pointer(skb) - RTL8_4_TAG_LEN))) + return NULL; + + if (pskb_trim_rcsum(skb, skb->len - RTL8_4_TAG_LEN)) + return NULL; + + return skb; +} + +/* Ethertype version */ +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, +}; + +DSA_TAG_DRIVER(rtl8_4_netdev_ops); + +MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL8_4); + +/* Tail version */ +static const struct dsa_device_ops rtl8_4t_netdev_ops = { + .name = "rtl8_4t", + .proto = DSA_TAG_PROTO_RTL8_4T, + .xmit = rtl8_4t_tag_xmit, + .rcv = rtl8_4t_tag_rcv, + .needed_tailroom = RTL8_4_TAG_LEN, +}; + +DSA_TAG_DRIVER(rtl8_4t_netdev_ops); + +MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL8_4T); + +static struct dsa_tag_driver *dsa_tag_drivers[] = { + &DSA_TAG_DRIVER_NAME(rtl8_4_netdev_ops), + &DSA_TAG_DRIVER_NAME(rtl8_4t_netdev_ops), +}; +module_dsa_tag_drivers(dsa_tag_drivers); + +MODULE_LICENSE("GPL"); |