ethtool: Complete kernel-doc comments for RX flow filter and hash control

There are now several interfaces within the ethtool API for getting
and setting RX flow filtering and hashing behaviour, most of which are
poorly documented.  This adds kernel-doc comments for all these
interfaces, based on the existing incomplete comments and on the
initial implementations.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -314,9 +314,20 @@ enum ethtool_flags {
 };
 
 /* The following structures are for supporting RX network flow
- * classification configuration. Note, all multibyte fields, e.g.,
- * ip4src, ip4dst, psrc, pdst, spi, etc. are expected to be in network
- * byte order.
+ * classification and RX n-tuple configuration. Note, all multibyte
+ * fields, e.g., ip4src, ip4dst, psrc, pdst, spi, etc. are expected to
+ * be in network byte order.
+ */
+
+/**
+ * struct ethtool_tcpip4_spec - flow specification for TCP/IPv4 etc.
+ * @ip4src: Source host
+ * @ip4dst: Destination host
+ * @psrc: Source port
+ * @pdst: Destination port
+ * @tos: Type-of-service
+ *
+ * This can be used to specify a TCP/IPv4, UDP/IPv4 or SCTP/IPv4 flow.
  */
 struct ethtool_tcpip4_spec {
 	__be32	ip4src;
@@ -326,6 +337,15 @@ struct ethtool_tcpip4_spec {
 	__u8    tos;
 };
 
+/**
+ * struct ethtool_ah_espip4_spec - flow specification for IPsec/IPv4
+ * @ip4src: Source host
+ * @ip4dst: Destination host
+ * @spi: Security parameters index
+ * @tos: Type-of-service
+ *
+ * This can be used to specify an IPsec transport or tunnel over IPv4.
+ */
 struct ethtool_ah_espip4_spec {
 	__be32	ip4src;
 	__be32	ip4dst;
@@ -348,6 +368,15 @@ struct ethtool_ether_spec {
 #define	ETH_RX_NFC_IP4	1
 #define	ETH_RX_NFC_IP6	2
 
+/**
+ * struct ethtool_usrip4_spec - general flow specification for IPv4
+ * @ip4src: Source host
+ * @ip4dst: Destination host
+ * @l4_4_bytes: First 4 bytes of transport (layer 4) header
+ * @tos: Type-of-service
+ * @ip_ver: Value must be %ETH_RX_NFC_IP4; mask must be 0
+ * @proto: Transport protocol number; mask must be 0
+ */
 struct ethtool_usrip4_spec {
 	__be32	ip4src;
 	__be32	ip4dst;
@@ -357,6 +386,15 @@ struct ethtool_usrip4_spec {
 	__u8    proto;
 };
 
+/**
+ * struct ethtool_rx_flow_spec - specification for RX flow filter
+ * @flow_type: Type of match to perform, e.g. %TCP_V4_FLOW
+ * @h_u: Flow fields to match (dependent on @flow_type)
+ * @m_u: Masks for flow field bits to be ignored
+ * @ring_cookie: RX ring/queue index to deliver to, or %RX_CLS_FLOW_DISC
+ *	if packets should be discarded
+ * @location: Index of filter in hardware table
+ */
 struct ethtool_rx_flow_spec {
 	__u32		flow_type;
 	union {
@@ -369,32 +407,87 @@ struct ethtool_rx_flow_spec {
 		struct ethtool_ether_spec		ether_spec;
 		struct ethtool_usrip4_spec		usr_ip4_spec;
 		__u8					hdata[64];
-	} h_u, m_u; /* entry, mask */
+	} h_u, m_u;
 	__u64		ring_cookie;
 	__u32		location;
 };
 
+/**
+ * struct ethtool_rxnfc - command to get or set RX flow classification rules
+ * @cmd: Specific command number - %ETHTOOL_GRXFH, %ETHTOOL_SRXFH,
+ *	%ETHTOOL_GRXRINGS, %ETHTOOL_GRXCLSRLCNT, %ETHTOOL_GRXCLSRULE,
+ *	%ETHTOOL_GRXCLSRLALL, %ETHTOOL_SRXCLSRLDEL or %ETHTOOL_SRXCLSRLINS
+ * @flow_type: Type of flow to be affected, e.g. %TCP_V4_FLOW
+ * @data: Command-dependent value
+ * @fs: Flow filter specification
+ * @rule_cnt: Number of rules to be affected
+ * @rule_locs: Array of valid rule indices
+ *
+ * For %ETHTOOL_GRXFH and %ETHTOOL_SRXFH, @data is a bitmask indicating
+ * the fields included in the flow hash, e.g. %RXH_IP_SRC.  The following
+ * structure fields must not be used.
+ *
+ * For %ETHTOOL_GRXRINGS, @data is set to the number of RX rings/queues
+ * on return.
+ *
+ * For %ETHTOOL_GRXCLSRLCNT, @rule_cnt is set to the number of defined
+ * rules on return.
+ *
+ * For %ETHTOOL_GRXCLSRULE, @fs.@location specifies the index of an
+ * existing filter rule on entry and @fs contains the rule on return.
+ *
+ * For %ETHTOOL_GRXCLSRLALL, @rule_cnt specifies the array size of the
+ * user buffer for @rule_locs on entry.  On return, @data is the size
+ * of the filter table and @rule_locs contains the indices of the
+ * defined rules.
+ *
+ * For %ETHTOOL_SRXCLSRLINS, @fs specifies the filter rule to add or
+ * update.  @fs.@location specifies the index to use and must not be
+ * ignored.
+ *
+ * For %ETHTOOL_SRXCLSRLDEL, @fs.@location specifies the index of an
+ * existing filter rule on entry.
+ *
+ * Implementation of indexed classification rules generally requires a
+ * TCAM.
+ */
 struct ethtool_rxnfc {
 	__u32				cmd;
 	__u32				flow_type;
-	/* The rx flow hash value or the rule DB size */
 	__u64				data;
-	/* The following fields are not valid and must not be used for
-	 * the ETHTOOL_{G,X}RXFH commands. */
 	struct ethtool_rx_flow_spec	fs;
 	__u32				rule_cnt;
 	__u32				rule_locs[0];
 };
 
+/**
+ * struct ethtool_rxfh_indir - command to get or set RX flow hash indirection
+ * @cmd: Specific command number - %ETHTOOL_GRXFHINDIR or %ETHTOOL_SRXFHINDIR
+ * @size: On entry, the array size of the user buffer.  On return from
+ *	%ETHTOOL_GRXFHINDIR, the array size of the hardware indirection table.
+ * @ring_index: RX ring/queue index for each hash value
+ */
 struct ethtool_rxfh_indir {
 	__u32	cmd;
-	/* On entry, this is the array size of the user buffer.  On
-	 * return from ETHTOOL_GRXFHINDIR, this is the array size of
-	 * the hardware indirection table. */
 	__u32	size;
-	__u32	ring_index[0];	/* ring/queue index for each hash value */
+	__u32	ring_index[0];
 };
 
+/**
+ * struct ethtool_rx_ntuple_flow_spec - specification for RX flow filter
+ * @flow_type: Type of match to perform, e.g. %TCP_V4_FLOW
+ * @h_u: Flow field values to match (dependent on @flow_type)
+ * @m_u: Masks for flow field value bits to be ignored
+ * @vlan_tag: VLAN tag to match
+ * @vlan_tag_mask: Mask for VLAN tag bits to be ignored
+ * @data: Driver-dependent data to match
+ * @data_mask: Mask for driver-dependent data bits to be ignored
+ * @action: RX ring/queue index to deliver to (non-negative) or other action
+ *	(negative, e.g. %ETHTOOL_RXNTUPLE_ACTION_DROP)
+ *
+ * Zero values in @h_u may be ignored, as if all the corresponding
+ * mask bits were set.
+ */
 struct ethtool_rx_ntuple_flow_spec {
 	__u32		 flow_type;
 	union {
@@ -407,18 +500,22 @@ struct ethtool_rx_ntuple_flow_spec {
 		struct ethtool_ether_spec		ether_spec;
 		struct ethtool_usrip4_spec		usr_ip4_spec;
 		__u8					hdata[64];
-	} h_u, m_u; /* entry, mask */
+	} h_u, m_u;
 
 	__u16	        vlan_tag;
 	__u16	        vlan_tag_mask;
-	__u64		data;      /* user-defined flow spec data */
-	__u64		data_mask; /* user-defined flow spec mask */
+	__u64		data;
+	__u64		data_mask;
 
-	/* signed to distinguish between queue and actions (DROP) */
 	__s32		action;
-#define ETHTOOL_RXNTUPLE_ACTION_DROP -1
+#define ETHTOOL_RXNTUPLE_ACTION_DROP -1		/* drop packet */
 };
 
+/**
+ * struct ethtool_rx_ntuple - command to set RX flow filter
+ * @cmd: Command number - %ETHTOOL_SRXNTUPLE
+ * @fs: Flow filter specification
+ */
 struct ethtool_rx_ntuple {
 	__u32					cmd;
 	struct ethtool_rx_ntuple_flow_spec	fs;