[net-next RFC PATCH v4 08/15] net: dsa: tag_qca: add define for handling mdio Ethernet packet

Ansuel Smith
2021-12-11T19:58:32Z

Add all the required define to prepare support for mdio read/write in
Ethernet packet. Any packet of this type has to be dropped as the only
use of these special packet is receive ack for an mdio write request or
receive data for an mdio read request.
A struct is used that emulates the Ethernet header but is used for a
different purpose.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
include/linux/dsa/tag_qca.h | 41 +++++++++++++++++++++++++++++++++++++
net/dsa/tag_qca.c | 13 +++++++++---
2 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/include/linux/dsa/tag_qca.h b/include/linux/dsa/tag_qca.h
index c02d2d39ff4a..578a4aeafd92 100644
--- a/include/linux/dsa/tag_qca.h
+++ b/include/linux/dsa/tag_qca.h
@@ -12,10 +12,51 @@
#define QCA_HDR_RECV_FRAME_IS_TAGGED BIT(3)
#define QCA_HDR_RECV_SOURCE_PORT GENMASK(2, 0)

+/* Packet type for recv */
+#define QCA_HDR_RECV_TYPE_NORMAL 0x0
+#define QCA_HDR_RECV_TYPE_MIB 0x1
+#define QCA_HDR_RECV_TYPE_RW_REG_ACK 0x2
+
#define QCA_HDR_XMIT_VERSION GENMASK(15, 14)
#define QCA_HDR_XMIT_PRIORITY GENMASK(13, 11)
#define QCA_HDR_XMIT_CONTROL GENMASK(10, 8)
#define QCA_HDR_XMIT_FROM_CPU BIT(7)
#define QCA_HDR_XMIT_DP_BIT GENMASK(6, 0)

+/* Packet type for xmit */
+#define QCA_HDR_XMIT_TYPE_NORMAL 0x0
+#define QCA_HDR_XMIT_TYPE_RW_REG 0x1
+
+#define MDIO_CHECK_CODE_VAL 0x5
+
+/* Specific define for in-band MDIO read/write with Ethernet packet */
+#define QCA_HDR_MDIO_SEQ_LEN 4 /* 4 byte for the seq */
+#define QCA_HDR_MDIO_COMMAND_LEN 4 /* 4 byte for the command */
+#define QCA_HDR_MDIO_DATA1_LEN 4 /* First 4 byte for the mdio data */
+#define QCA_HDR_MDIO_HEADER_LEN (QCA_HDR_MDIO_SEQ_LEN + \
+ QCA_HDR_MDIO_COMMAND_LEN + \
+ QCA_HDR_MDIO_DATA1_LEN)
+
+#define QCA_HDR_MDIO_DATA2_LEN 12 /* Other 12 byte for the mdio data */
+#define QCA_HDR_MDIO_PADDING_LEN 34 /* Padding to reach the min Ethernet packet */
+
+#define QCA_HDR_MDIO_PKG_LEN (QCA_HDR_MDIO_HEADER_LEN + \
+ QCA_HDR_LEN + \
+ QCA_HDR_MDIO_DATA2_LEN + \
+ QCA_HDR_MDIO_PADDING_LEN)
+
+#define QCA_HDR_MDIO_SEQ_NUM GENMASK(31, 0) /* 63, 32 */
+#define QCA_HDR_MDIO_CHECK_CODE GENMASK(31, 29) /* 31, 29 */
+#define QCA_HDR_MDIO_CMD BIT(28) /* 28 */
+#define QCA_HDR_MDIO_LENGTH GENMASK(23, 20) /* 23, 20 */
+#define QCA_HDR_MDIO_ADDR GENMASK(18, 0) /* 18, 0 */
+
+/* Special struct emulating a Ethernet header */
+struct mdio_ethhdr {
+ u32 command; /* command bit 31:0 */
+ u32 seq; /* seq 63:32 */
+ u32 mdio_data; /* first 4byte mdio */
+ u16 hdr; /* qca hdr */
+} __packed;
+
#endif /* __TAG_QCA_H */
diff --git a/net/dsa/tag_qca.c b/net/dsa/tag_qca.c
index f8df49d5956f..b91f9f1b2deb 100644
--- a/net/dsa/tag_qca.c
+++ b/net/dsa/tag_qca.c
@@ -32,10 +32,10 @@ static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)

static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev)
{
- u8 ver;
- u16 hdr;
- int port;
+ u16 hdr, pk_type;
__be16 *phdr;
+ int port;
+ u8 ver;

if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
return NULL;
@@ -48,6 +48,13 @@ static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev)
if (unlikely(ver != QCA_HDR_VERSION))
return NULL;

+ /* Get pk type */
+ pk_type = FIELD_GET(QCA_HDR_RECV_TYPE, hdr);
+
+ /* MDIO read/write packet */
+ if (pk_type == QCA_HDR_RECV_TYPE_RW_REG_ACK)
+ return NULL;
+
/* Remove QCA tag and recalculate checksum */
skb_pull_rcsum(skb, QCA_HDR_LEN);
dsa_strip_etype_header(skb, QCA_HDR_LEN);
--
2.32.0