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Date:   Sat, 17 Dec 2022 01:48:21 +0100
From:   Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
To:     Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Oleksij Rempel <o.rempel@pengutronix.de>
Subject: [PATCH v7 net-next 1/5] net/ethtool: add netlink interface for the
 PLCA RS
Message-ID: <6e014ed12216b6dfbc96ce5bce955f9219c8c626.1671234284.git.piergiorgio.beruto@gmail.com>
References: <cover.1671234284.git.piergiorgio.beruto@gmail.com>
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In-Reply-To: <cover.1671234284.git.piergiorgio.beruto@gmail.com>
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Add support for configuring the PLCA Reconciliation Sublayer on
multi-drop PHYs that support IEEE802.3cg-2019 Clause 148 (e.g.,
10BASE-T1S). This patch adds the appropriate netlink interface
to ethtool.

Signed-off-by: Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
---
 Documentation/networking/ethtool-netlink.rst | 138 ++++++++++
 MAINTAINERS                                  |   6 +
 include/linux/ethtool.h                      |  12 +
 include/linux/phy.h                          |  57 ++++
 include/uapi/linux/ethtool_netlink.h         |  25 ++
 net/ethtool/Makefile                         |   2 +-
 net/ethtool/netlink.c                        |  29 ++
 net/ethtool/netlink.h                        |   6 +
 net/ethtool/plca.c                           | 276 +++++++++++++++++++
 9 files changed, 550 insertions(+), 1 deletion(-)
 create mode 100644 net/ethtool/plca.c

diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index f10f8eb44255..c59b542eb693 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -1716,6 +1716,141 @@ being used. Current supported options are toeplitz, xor or crc32.
 ETHTOOL_A_RSS_INDIR attribute returns RSS indrection table where each byte
 indicates queue number.
 
+PLCA_GET_CFG
+============
+
+Gets the IEEE 802.3cg-2019 Clause 148 Physical Layer Collision Avoidance
+(PLCA) Reconciliation Sublayer (RS) attributes.
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_PLCA_HEADER``              nested  request header
+  =====================================  ======  ==========================
+
+Kernel response contents:
+
+  ======================================  ======  =============================
+  ``ETHTOOL_A_PLCA_HEADER``               nested  reply header
+  ``ETHTOOL_A_PLCA_VERSION``              u16     Supported PLCA management
+                                                  interface standard/version
+  ``ETHTOOL_A_PLCA_ENABLED``              u8      PLCA Admin State
+  ``ETHTOOL_A_PLCA_NODE_ID``              u32     PLCA unique local node ID
+  ``ETHTOOL_A_PLCA_NODE_CNT``             u32     Number of PLCA nodes on the
+                                                  network, including the
+                                                  coordinator
+  ``ETHTOOL_A_PLCA_TO_TMR``               u32     Transmit Opportunity Timer
+                                                  value in bit-times (BT)
+  ``ETHTOOL_A_PLCA_BURST_CNT``            u32     Number of additional packets
+                                                  the node is allowed to send
+                                                  within a single TO
+  ``ETHTOOL_A_PLCA_BURST_TMR``            u32     Time to wait for the MAC to
+                                                  transmit a new frame before
+                                                  terminating the burst
+  ======================================  ======  =============================
+
+When set, the optional ``ETHTOOL_A_PLCA_VERSION`` attribute indicates which
+standard and version the PLCA management interface complies to. When not set,
+the interface is vendor-specific and (possibly) supplied by the driver.
+The OPEN Alliance SIG specifies a standard register map for 10BASE-T1S PHYs
+embedding the PLCA Reconcialiation Sublayer. See "10BASE-T1S PLCA Management
+Registers" at https://www.opensig.org/about/specifications/.
+
+When set, the optional ``ETHTOOL_A_PLCA_ENABLED`` attribute indicates the
+administrative state of the PLCA RS. When not set, the node operates in "plain"
+CSMA/CD mode. This option is corresponding to ``IEEE 802.3cg-2019`` 30.16.1.1.1
+aPLCAAdminState / 30.16.1.2.1 acPLCAAdminControl.
+
+When set, the optional ``ETHTOOL_A_PLCA_NODE_ID`` attribute indicates the
+configured local node ID of the PHY. This ID determines which transmit
+opportunity (TO) is reserved for the node to transmit into. This option is
+corresponding to ``IEEE 802.3cg-2019`` 30.16.1.1.4 aPLCALocalNodeID. The valid
+range for this attribute is [0 .. 255] where 255 means "not configured".
+
+When set, the optional ``ETHTOOL_A_PLCA_NODE_CNT`` attribute indicates the
+configured maximum number of PLCA nodes on the mixing-segment. This number
+determines the total number of transmit opportunities generated during a
+PLCA cycle. This attribute is relevant only for the PLCA coordinator, which is
+the node with aPLCALocalNodeID set to 0. Follower nodes ignore this setting.
+This option is corresponding to ``IEEE 802.3cg-2019`` 30.16.1.1.3
+aPLCANodeCount. The valid range for this attribute is [1 .. 255].
+
+When set, the optional ``ETHTOOL_A_PLCA_TO_TMR`` attribute indicates the
+configured value of the transmit opportunity timer in bit-times. This value
+must be set equal across all nodes sharing the medium for PLCA to work
+correctly. This option is corresponding to ``IEEE 802.3cg-2019`` 30.16.1.1.5
+aPLCATransmitOpportunityTimer. The valid range for this attribute is
+[0 .. 255].
+
+When set, the optional ``ETHTOOL_A_PLCA_BURST_CNT`` attribute indicates the
+configured number of extra packets that the node is allowed to send during a
+single transmit opportunity. By default, this attribute is 0, meaning that
+the node can only send a sigle frame per TO. When greater than 0, the PLCA RS
+keeps the TO after any transmission, waiting for the MAC to send a new frame
+for up to aPLCABurstTimer BTs. This can only happen a number of times per PLCA
+cycle up to the value of this parameter. After that, the burst is over and the
+normal counting of TOs resumes. This option is corresponding to
+``IEEE 802.3cg-2019`` 30.16.1.1.6 aPLCAMaxBurstCount. The valid range for this
+attribute is [0 .. 255].
+
+When set, the optional ``ETHTOOL_A_PLCA_BURST_TMR`` attribute indicates how
+many bit-times the PLCA RS waits for the MAC to initiate a new transmission
+when aPLCAMaxBurstCount is greater than 0. If the MAC fails to send a new
+frame within this time, the burst ends and the counting of TOs resumes.
+Otherwise, the new frame is sent as part of the current burst. This option
+is corresponding to ``IEEE 802.3cg-2019`` 30.16.1.1.7 aPLCABurstTimer. The
+valid range for this attribute is [0 .. 255]. Although, the value should be
+set greater than the Inter-Frame-Gap (IFG) time of the MAC (plus some margin)
+for PLCA burst mode to work as intended.
+
+PLCA_SET_CFG
+============
+
+Sets PLCA RS parameters.
+
+Request contents:
+
+  ======================================  ======  =============================
+  ``ETHTOOL_A_PLCA_HEADER``               nested  request header
+  ``ETHTOOL_A_PLCA_ENABLED``              u8      PLCA Admin State
+  ``ETHTOOL_A_PLCA_NODE_ID``              u8      PLCA unique local node ID
+  ``ETHTOOL_A_PLCA_NODE_CNT``             u8      Number of PLCA nodes on the
+                                                  netkork, including the
+                                                  coordinator
+  ``ETHTOOL_A_PLCA_TO_TMR``               u8      Transmit Opportunity Timer
+                                                  value in bit-times (BT)
+  ``ETHTOOL_A_PLCA_BURST_CNT``            u8      Number of additional packets
+                                                  the node is allowed to send
+                                                  within a single TO
+  ``ETHTOOL_A_PLCA_BURST_TMR``            u8      Time to wait for the MAC to
+                                                  transmit a new frame before
+                                                  terminating the burst
+  ======================================  ======  =============================
+
+For a description of each attribute, see ``PLCA_GET_CFG``.
+
+PLCA_GET_STATUS
+===============
+
+Gets PLCA RS status information.
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_A_PLCA_HEADER``              nested  request header
+  =====================================  ======  ==========================
+
+Kernel response contents:
+
+  ======================================  ======  =============================
+  ``ETHTOOL_A_PLCA_HEADER``               nested  reply header
+  ``ETHTOOL_A_PLCA_STATUS``               u8      PLCA RS operational status
+  ======================================  ======  =============================
+
+When set, the ``ETHTOOL_A_PLCA_STATUS`` attribute indicates whether the node is
+detecting the presence of the BEACON on the network. This flag is
+corresponding to ``IEEE 802.3cg-2019`` 30.16.1.1.2 aPLCAStatus.
+
 Request translation
 ===================
 
@@ -1817,4 +1952,7 @@ are netlink only.
   n/a                                 ``ETHTOOL_MSG_PHC_VCLOCKS_GET``
   n/a                                 ``ETHTOOL_MSG_MODULE_GET``
   n/a                                 ``ETHTOOL_MSG_MODULE_SET``
+  n/a                                 ``ETHTOOL_MSG_PLCA_GET_CFG``
+  n/a                                 ``ETHTOOL_MSG_PLCA_SET_CFG``
+  n/a                                 ``ETHTOOL_MSG_PLCA_GET_STATUS``
   =================================== =====================================
diff --git a/MAINTAINERS b/MAINTAINERS
index 5a4526a171d6..c5e49c218796 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16515,6 +16515,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/chemical/plantower,pms7003.yaml
 F:	drivers/iio/chemical/pms7003.c
 
+PLCA RECONCILIATION SUBLAYER (IEEE802.3 Clause 148)
+M:	Piergiorgio Beruto <piergiorgio.beruto@gmail.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+F:	net/ethtool/plca.c
+
 PLDMFW LIBRARY
 M:	Jacob Keller <jacob.e.keller@intel.com>
 S:	Maintained
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 9e0a76fc7de9..d0da303f6634 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -802,12 +802,17 @@ int ethtool_virtdev_set_link_ksettings(struct net_device *dev,
 
 struct phy_device;
 struct phy_tdr_config;
+struct phy_plca_cfg;
+struct phy_plca_status;
 
 /**
  * struct ethtool_phy_ops - Optional PHY device options
  * @get_sset_count: Get number of strings that @get_strings will write.
  * @get_strings: Return a set of strings that describe the requested objects
  * @get_stats: Return extended statistics about the PHY device.
+ * @get_plca_cfg: Return PLCA configuration.
+ * @set_plca_cfg: Set PLCA configuration.
+ * @get_plca_status: Get PLCA configuration.
  * @start_cable_test: Start a cable test
  * @start_cable_test_tdr: Start a Time Domain Reflectometry cable test
  *
@@ -819,6 +824,13 @@ struct ethtool_phy_ops {
 	int (*get_strings)(struct phy_device *dev, u8 *data);
 	int (*get_stats)(struct phy_device *dev,
 			 struct ethtool_stats *stats, u64 *data);
+	int (*get_plca_cfg)(struct phy_device *dev,
+			    struct phy_plca_cfg *plca_cfg);
+	int (*set_plca_cfg)(struct phy_device *dev,
+			    const struct phy_plca_cfg *plca_cfg,
+			    struct netlink_ext_ack *extack);
+	int (*get_plca_status)(struct phy_device *dev,
+			       struct phy_plca_status *plca_st);
 	int (*start_cable_test)(struct phy_device *phydev,
 				struct netlink_ext_ack *extack);
 	int (*start_cable_test_tdr)(struct phy_device *phydev,
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 71eeb4e3b1fd..c2c04b989cc2 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -765,6 +765,63 @@ struct phy_tdr_config {
 };
 #define PHY_PAIR_ALL -1
 
+/**
+ * struct phy_plca_cfg - Configuration of the PLCA (Physical Layer Collision
+ * Avoidance) Reconciliation Sublayer.
+ *
+ * @version: read-only PLCA register map version. -1 = not available. Ignored
+ *   when setting the configuration. Format is the same as reported by the PLCA
+ *   IDVER register (31.CA00). -1 = not available.
+ * @enabled: PLCA configured mode (enabled/disabled). -1 = not available / don't
+ *   set. 0 = disabled, anything else = enabled.
+ * @node_id: the PLCA local node identifier. -1 = not available / don't set.
+ *   Allowed values [0 .. 254]. 255 = node disabled.
+ * @node_cnt: the PLCA node count (maximum number of nodes having a TO). Only
+ *   meaningful for the coordinator (node_id = 0). -1 = not available / don't
+ *   set. Allowed values [1 .. 255].
+ * @to_tmr: The value of the PLCA to_timer in bit-times, which determines the
+ *   PLCA transmit opportunity window opening. See IEEE802.3 Clause 148 for
+ *   more details. The to_timer shall be set equal over all nodes.
+ *   -1 = not available / don't set. Allowed values [0 .. 255].
+ * @burst_cnt: controls how many additional frames a node is allowed to send in
+ *   single transmit opportunity (TO). The default value of 0 means that the
+ *   node is allowed exactly one frame per TO. A value of 1 allows two frames
+ *   per TO, and so on. -1 = not available / don't set.
+ *   Allowed values [0 .. 255].
+ * @burst_tmr: controls how many bit times to wait for the MAC to send a new
+ *   frame before interrupting the burst. This value should be set to a value
+ *   greater than the MAC inter-packet gap (which is typically 96 bits).
+ *   -1 = not available / don't set. Allowed values [0 .. 255].
+ *
+ * A structure containing configuration parameters for setting/getting the PLCA
+ * RS configuration. The driver does not need to implement all the parameters,
+ * but should report what is actually used.
+ */
+struct phy_plca_cfg {
+	int version;
+	int enabled;
+	int node_id;
+	int node_cnt;
+	int to_tmr;
+	int burst_cnt;
+	int burst_tmr;
+};
+
+/**
+ * struct phy_plca_status - Status of the PLCA (Physical Layer Collision
+ * Avoidance) Reconciliation Sublayer.
+ *
+ * @pst: The PLCA status as reported by the PST bit in the PLCA STATUS
+ *	register(31.CA03), indicating BEACON activity.
+ *
+ * A structure containing status information of the PLCA RS configuration.
+ * The driver does not need to implement all the parameters, but should report
+ * what is actually used.
+ */
+struct phy_plca_status {
+	bool pst;
+};
+
 /**
  * struct phy_driver - Driver structure for a particular PHY type
  *
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 5799a9db034e..75b3d6d476ff 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -52,6 +52,9 @@ enum {
 	ETHTOOL_MSG_PSE_GET,
 	ETHTOOL_MSG_PSE_SET,
 	ETHTOOL_MSG_RSS_GET,
+	ETHTOOL_MSG_PLCA_GET_CFG,
+	ETHTOOL_MSG_PLCA_SET_CFG,
+	ETHTOOL_MSG_PLCA_GET_STATUS,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_USER_CNT,
@@ -99,6 +102,9 @@ enum {
 	ETHTOOL_MSG_MODULE_NTF,
 	ETHTOOL_MSG_PSE_GET_REPLY,
 	ETHTOOL_MSG_RSS_GET_REPLY,
+	ETHTOOL_MSG_PLCA_GET_CFG_REPLY,
+	ETHTOOL_MSG_PLCA_GET_STATUS_REPLY,
+	ETHTOOL_MSG_PLCA_NTF,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,
@@ -894,6 +900,25 @@ enum {
 	ETHTOOL_A_RSS_MAX = (__ETHTOOL_A_RSS_CNT - 1),
 };
 
+/* PLCA */
+
+enum {
+	ETHTOOL_A_PLCA_UNSPEC,
+	ETHTOOL_A_PLCA_HEADER,			/* nest - _A_HEADER_* */
+	ETHTOOL_A_PLCA_VERSION,			/* u16 */
+	ETHTOOL_A_PLCA_ENABLED,			/* u8  */
+	ETHTOOL_A_PLCA_STATUS,			/* u8  */
+	ETHTOOL_A_PLCA_NODE_CNT,		/* u32 */
+	ETHTOOL_A_PLCA_NODE_ID,			/* u32 */
+	ETHTOOL_A_PLCA_TO_TMR,			/* u32 */
+	ETHTOOL_A_PLCA_BURST_CNT,		/* u32 */
+	ETHTOOL_A_PLCA_BURST_TMR,		/* u32 */
+
+	/* add new constants above here */
+	__ETHTOOL_A_PLCA_CNT,
+	ETHTOOL_A_PLCA_MAX = (__ETHTOOL_A_PLCA_CNT - 1)
+};
+
 /* generic netlink info */
 #define ETHTOOL_GENL_NAME "ethtool"
 #define ETHTOOL_GENL_VERSION 1
diff --git a/net/ethtool/Makefile b/net/ethtool/Makefile
index 228f13df2e18..563864c1bf5a 100644
--- a/net/ethtool/Makefile
+++ b/net/ethtool/Makefile
@@ -8,4 +8,4 @@ ethtool_nl-y	:= netlink.o bitset.o strset.o linkinfo.o linkmodes.o rss.o \
 		   linkstate.o debug.o wol.o features.o privflags.o rings.o \
 		   channels.o coalesce.o pause.o eee.o tsinfo.o cabletest.o \
 		   tunnels.o fec.o eeprom.o stats.o phc_vclocks.o module.o \
-		   pse-pd.o
+		   pse-pd.o plca.o
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index aee98be6237f..9f924875bba9 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -288,6 +288,8 @@ ethnl_default_requests[__ETHTOOL_MSG_USER_CNT] = {
 	[ETHTOOL_MSG_MODULE_GET]	= &ethnl_module_request_ops,
 	[ETHTOOL_MSG_PSE_GET]		= &ethnl_pse_request_ops,
 	[ETHTOOL_MSG_RSS_GET]		= &ethnl_rss_request_ops,
+	[ETHTOOL_MSG_PLCA_GET_CFG]	= &ethnl_plca_cfg_request_ops,
+	[ETHTOOL_MSG_PLCA_GET_STATUS]	= &ethnl_plca_status_request_ops,
 };
 
 static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
@@ -603,6 +605,7 @@ ethnl_default_notify_ops[ETHTOOL_MSG_KERNEL_MAX + 1] = {
 	[ETHTOOL_MSG_EEE_NTF]		= &ethnl_eee_request_ops,
 	[ETHTOOL_MSG_FEC_NTF]		= &ethnl_fec_request_ops,
 	[ETHTOOL_MSG_MODULE_NTF]	= &ethnl_module_request_ops,
+	[ETHTOOL_MSG_PLCA_NTF]		= &ethnl_plca_cfg_request_ops,
 };
 
 /* default notification handler */
@@ -696,6 +699,7 @@ static const ethnl_notify_handler_t ethnl_notify_handlers[] = {
 	[ETHTOOL_MSG_EEE_NTF]		= ethnl_default_notify,
 	[ETHTOOL_MSG_FEC_NTF]		= ethnl_default_notify,
 	[ETHTOOL_MSG_MODULE_NTF]	= ethnl_default_notify,
+	[ETHTOOL_MSG_PLCA_NTF]		= ethnl_default_notify,
 };
 
 void ethtool_notify(struct net_device *dev, unsigned int cmd, const void *data)
@@ -1047,6 +1051,31 @@ static const struct genl_ops ethtool_genl_ops[] = {
 		.policy = ethnl_rss_get_policy,
 		.maxattr = ARRAY_SIZE(ethnl_rss_get_policy) - 1,
 	},
+	{
+		.cmd	= ETHTOOL_MSG_PLCA_GET_CFG,
+		.doit	= ethnl_default_doit,
+		.start	= ethnl_default_start,
+		.dumpit	= ethnl_default_dumpit,
+		.done	= ethnl_default_done,
+		.policy = ethnl_plca_get_cfg_policy,
+		.maxattr = ARRAY_SIZE(ethnl_plca_get_cfg_policy) - 1,
+	},
+	{
+		.cmd	= ETHTOOL_MSG_PLCA_SET_CFG,
+		.flags	= GENL_UNS_ADMIN_PERM,
+		.doit	= ethnl_set_plca_cfg,
+		.policy = ethnl_plca_set_cfg_policy,
+		.maxattr = ARRAY_SIZE(ethnl_plca_set_cfg_policy) - 1,
+	},
+	{
+		.cmd	= ETHTOOL_MSG_PLCA_GET_STATUS,
+		.doit	= ethnl_default_doit,
+		.start	= ethnl_default_start,
+		.dumpit	= ethnl_default_dumpit,
+		.done	= ethnl_default_done,
+		.policy = ethnl_plca_get_status_policy,
+		.maxattr = ARRAY_SIZE(ethnl_plca_get_status_policy) - 1,
+	},
 };
 
 static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index 3753787ba233..f271266f6e28 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -347,6 +347,8 @@ extern const struct ethnl_request_ops ethnl_phc_vclocks_request_ops;
 extern const struct ethnl_request_ops ethnl_module_request_ops;
 extern const struct ethnl_request_ops ethnl_pse_request_ops;
 extern const struct ethnl_request_ops ethnl_rss_request_ops;
+extern const struct ethnl_request_ops ethnl_plca_cfg_request_ops;
+extern const struct ethnl_request_ops ethnl_plca_status_request_ops;
 
 extern const struct nla_policy ethnl_header_policy[ETHTOOL_A_HEADER_FLAGS + 1];
 extern const struct nla_policy ethnl_header_policy_stats[ETHTOOL_A_HEADER_FLAGS + 1];
@@ -388,6 +390,9 @@ extern const struct nla_policy ethnl_module_set_policy[ETHTOOL_A_MODULE_POWER_MO
 extern const struct nla_policy ethnl_pse_get_policy[ETHTOOL_A_PSE_HEADER + 1];
 extern const struct nla_policy ethnl_pse_set_policy[ETHTOOL_A_PSE_MAX + 1];
 extern const struct nla_policy ethnl_rss_get_policy[ETHTOOL_A_RSS_CONTEXT + 1];
+extern const struct nla_policy ethnl_plca_get_cfg_policy[ETHTOOL_A_PLCA_HEADER + 1];
+extern const struct nla_policy ethnl_plca_set_cfg_policy[ETHTOOL_A_PLCA_MAX + 1];
+extern const struct nla_policy ethnl_plca_get_status_policy[ETHTOOL_A_PLCA_HEADER + 1];
 
 int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info);
@@ -408,6 +413,7 @@ int ethnl_tunnel_info_dumpit(struct sk_buff *skb, struct netlink_callback *cb);
 int ethnl_set_fec(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_module(struct sk_buff *skb, struct genl_info *info);
 int ethnl_set_pse(struct sk_buff *skb, struct genl_info *info);
+int ethnl_set_plca_cfg(struct sk_buff *skb, struct genl_info *info);
 
 extern const char stats_std_names[__ETHTOOL_STATS_CNT][ETH_GSTRING_LEN];
 extern const char stats_eth_phy_names[__ETHTOOL_A_STATS_ETH_PHY_CNT][ETH_GSTRING_LEN];
diff --git a/net/ethtool/plca.c b/net/ethtool/plca.c
new file mode 100644
index 000000000000..d59075744c2e
--- /dev/null
+++ b/net/ethtool/plca.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/phy.h>
+#include <linux/ethtool_netlink.h>
+
+#include "netlink.h"
+#include "common.h"
+
+struct plca_req_info {
+	struct ethnl_req_info		base;
+};
+
+struct plca_reply_data {
+	struct ethnl_reply_data		base;
+	struct phy_plca_cfg		plca_cfg;
+	struct phy_plca_status		plca_st;
+};
+
+// Helpers ------------------------------------------------------------------ //
+
+#define PLCA_REPDATA(__reply_base) \
+	container_of(__reply_base, struct plca_reply_data, base)
+
+static inline void plca_update_sint(int *dst, const struct nlattr *attr,
+				    bool *mod)
+{
+	if (attr) {
+		*dst = nla_get_u32(attr);
+		*mod = true;
+	}
+}
+
+// PLCA get configuration message ------------------------------------------- //
+
+const struct nla_policy ethnl_plca_get_cfg_policy[] = {
+	[ETHTOOL_A_PLCA_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static int plca_get_cfg_prepare_data(const struct ethnl_req_info *req_base,
+				     struct ethnl_reply_data *reply_base,
+				     struct genl_info *info)
+{
+	struct plca_reply_data *data = PLCA_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	const struct ethtool_phy_ops *ops;
+	int ret;
+
+	// check that the PHY device is available and connected
+	if (!dev->phydev) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	// note: rtnl_lock is held already by ethnl_default_doit
+	ops = ethtool_phy_ops;
+	if (!ops || !ops->get_plca_cfg) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		goto out;
+
+	memset(&data->plca_cfg, 0xff,
+	       sizeof_field(struct plca_reply_data, plca_cfg));
+
+	ret = ops->get_plca_cfg(dev->phydev, &data->plca_cfg);
+	ethnl_ops_complete(dev);
+
+out:
+	return ret;
+}
+
+static int plca_get_cfg_reply_size(const struct ethnl_req_info *req_base,
+				   const struct ethnl_reply_data *reply_base)
+{
+	return nla_total_size(sizeof(u16)) +	/* _VERSION */
+	       nla_total_size(sizeof(u8)) +	/* _ENABLED */
+	       nla_total_size(sizeof(u32)) +	/* _NODE_CNT */
+	       nla_total_size(sizeof(u32)) +	/* _NODE_ID */
+	       nla_total_size(sizeof(u32)) +	/* _TO_TIMER */
+	       nla_total_size(sizeof(u32)) +	/* _BURST_COUNT */
+	       nla_total_size(sizeof(u32));	/* _BURST_TIMER */
+}
+
+static int plca_get_cfg_fill_reply(struct sk_buff *skb,
+				   const struct ethnl_req_info *req_base,
+				   const struct ethnl_reply_data *reply_base)
+{
+	const struct plca_reply_data *data = PLCA_REPDATA(reply_base);
+	const struct phy_plca_cfg *plca = &data->plca_cfg;
+
+	if ((plca->version >= 0 &&
+	     nla_put_u16(skb, ETHTOOL_A_PLCA_VERSION, plca->version)) ||
+	    (plca->enabled >= 0 &&
+	     nla_put_u8(skb, ETHTOOL_A_PLCA_ENABLED, !!plca->enabled)) ||
+	    (plca->node_id >= 0 &&
+	     nla_put_u32(skb, ETHTOOL_A_PLCA_NODE_ID, plca->node_id)) ||
+	    (plca->node_cnt >= 0 &&
+	     nla_put_u32(skb, ETHTOOL_A_PLCA_NODE_CNT, plca->node_cnt)) ||
+	    (plca->to_tmr >= 0 &&
+	     nla_put_u32(skb, ETHTOOL_A_PLCA_TO_TMR, plca->to_tmr)) ||
+	    (plca->burst_cnt >= 0 &&
+	     nla_put_u32(skb, ETHTOOL_A_PLCA_BURST_CNT, plca->burst_cnt)) ||
+	    (plca->burst_tmr >= 0 &&
+	     nla_put_u32(skb, ETHTOOL_A_PLCA_BURST_TMR, plca->burst_tmr)))
+		return -EMSGSIZE;
+
+	return 0;
+};
+
+const struct ethnl_request_ops ethnl_plca_cfg_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PLCA_GET_CFG,
+	.reply_cmd		= ETHTOOL_MSG_PLCA_GET_CFG_REPLY,
+	.hdr_attr		= ETHTOOL_A_PLCA_HEADER,
+	.req_info_size		= sizeof(struct plca_req_info),
+	.reply_data_size	= sizeof(struct plca_reply_data),
+
+	.prepare_data		= plca_get_cfg_prepare_data,
+	.reply_size		= plca_get_cfg_reply_size,
+	.fill_reply		= plca_get_cfg_fill_reply,
+};
+
+// PLCA set configuration message ------------------------------------------- //
+
+const struct nla_policy ethnl_plca_set_cfg_policy[] = {
+	[ETHTOOL_A_PLCA_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_PLCA_ENABLED]	= NLA_POLICY_MAX(NLA_U8, 1),
+	[ETHTOOL_A_PLCA_NODE_ID]	= NLA_POLICY_MAX(NLA_U32, 255),
+	[ETHTOOL_A_PLCA_NODE_CNT]	= NLA_POLICY_RANGE(NLA_U32, 1, 255),
+	[ETHTOOL_A_PLCA_TO_TMR]		= NLA_POLICY_MAX(NLA_U32, 255),
+	[ETHTOOL_A_PLCA_BURST_CNT]	= NLA_POLICY_MAX(NLA_U32, 255),
+	[ETHTOOL_A_PLCA_BURST_TMR]	= NLA_POLICY_MAX(NLA_U32, 255),
+};
+
+int ethnl_set_plca_cfg(struct sk_buff *skb, struct genl_info *info)
+{
+	struct ethnl_req_info req_info = {};
+	struct nlattr **tb = info->attrs;
+	const struct ethtool_phy_ops *ops;
+	struct phy_plca_cfg plca_cfg;
+	struct net_device *dev;
+	bool mod = false;
+	int ret;
+
+	ret = ethnl_parse_header_dev_get(&req_info,
+					 tb[ETHTOOL_A_PLCA_HEADER],
+					 genl_info_net(info), info->extack,
+					 true);
+	if (ret < 0)
+		return ret;
+
+	dev = req_info.dev;
+
+	rtnl_lock();
+
+	// check that the PHY device is available and connected
+	if (!dev->phydev) {
+		ret = -EOPNOTSUPP;
+		goto out_rtnl;
+	}
+
+	ops = ethtool_phy_ops;
+	if (!ops || !ops->set_plca_cfg) {
+		ret = -EOPNOTSUPP;
+		goto out_rtnl;
+	}
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		goto out_rtnl;
+
+	memset(&plca_cfg, 0xff, sizeof(plca_cfg));
+	plca_update_sint(&plca_cfg.enabled, tb[ETHTOOL_A_PLCA_ENABLED], &mod);
+	plca_update_sint(&plca_cfg.node_id, tb[ETHTOOL_A_PLCA_NODE_ID], &mod);
+	plca_update_sint(&plca_cfg.node_cnt, tb[ETHTOOL_A_PLCA_NODE_CNT], &mod);
+	plca_update_sint(&plca_cfg.to_tmr, tb[ETHTOOL_A_PLCA_TO_TMR], &mod);
+	plca_update_sint(&plca_cfg.burst_cnt, tb[ETHTOOL_A_PLCA_BURST_CNT],
+			 &mod);
+	plca_update_sint(&plca_cfg.burst_tmr, tb[ETHTOOL_A_PLCA_BURST_TMR],
+			 &mod);
+
+	ret = 0;
+	if (!mod)
+		goto out_ops;
+
+	ret = ops->set_plca_cfg(dev->phydev, &plca_cfg, info->extack);
+	if (ret < 0)
+		goto out_ops;
+
+	ethtool_notify(dev, ETHTOOL_MSG_PLCA_NTF, NULL);
+
+out_ops:
+	ethnl_ops_complete(dev);
+out_rtnl:
+	rtnl_unlock();
+	ethnl_parse_header_dev_put(&req_info);
+
+	return ret;
+}
+
+// PLCA get status message -------------------------------------------------- //
+
+const struct nla_policy ethnl_plca_get_status_policy[] = {
+	[ETHTOOL_A_PLCA_HEADER]		=
+		NLA_POLICY_NESTED(ethnl_header_policy),
+};
+
+static int plca_get_status_prepare_data(const struct ethnl_req_info *req_base,
+					struct ethnl_reply_data *reply_base,
+					struct genl_info *info)
+{
+	struct plca_reply_data *data = PLCA_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	const struct ethtool_phy_ops *ops;
+	int ret;
+
+	// check that the PHY device is available and connected
+	if (!dev->phydev) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	// note: rtnl_lock is held already by ethnl_default_doit
+	ops = ethtool_phy_ops;
+	if (!ops || !ops->get_plca_status) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		goto out;
+
+	memset(&data->plca_st, 0xff,
+	       sizeof_field(struct plca_reply_data, plca_st));
+
+	ret = ops->get_plca_status(dev->phydev, &data->plca_st);
+	ethnl_ops_complete(dev);
+out:
+	return ret;
+}
+
+static int plca_get_status_reply_size(const struct ethnl_req_info *req_base,
+				      const struct ethnl_reply_data *reply_base)
+{
+	return nla_total_size(sizeof(u8));	/* _STATUS */
+}
+
+static int plca_get_status_fill_reply(struct sk_buff *skb,
+				      const struct ethnl_req_info *req_base,
+				      const struct ethnl_reply_data *reply_base)
+{
+	const struct plca_reply_data *data = PLCA_REPDATA(reply_base);
+	const u8 status = data->plca_st.pst;
+
+	if (nla_put_u8(skb, ETHTOOL_A_PLCA_STATUS, !!status))
+		return -EMSGSIZE;
+
+	return 0;
+};
+
+const struct ethnl_request_ops ethnl_plca_status_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PLCA_GET_STATUS,
+	.reply_cmd		= ETHTOOL_MSG_PLCA_GET_STATUS_REPLY,
+	.hdr_attr		= ETHTOOL_A_PLCA_HEADER,
+	.req_info_size		= sizeof(struct plca_req_info),
+	.reply_data_size	= sizeof(struct plca_reply_data),
+
+	.prepare_data		= plca_get_status_prepare_data,
+	.reply_size		= plca_get_status_reply_size,
+	.fill_reply		= plca_get_status_fill_reply,
+};
-- 
2.37.4