net: ethtool: Add new power limit get and set features

This patch expands the status information provided by ethtool for PSE c33
with available power limit and available power limit ranges. It also adds
a call to pse_ethtool_set_pw_limit() to configure the PSE control power
limit.
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20240704-feature_poe_power_cap-v6-5-320003204264@bootlin.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/ethtool-netlink.rst

@@ -1730,24 +1730,28 @@ Request contents:
 
 Kernel response contents:
 
-  ======================================  ======  =============================
-  ``ETHTOOL_A_PSE_HEADER``                nested  reply header
-  ``ETHTOOL_A_PODL_PSE_ADMIN_STATE``         u32  Operational state of the PoDL
-                                                  PSE functions
-  ``ETHTOOL_A_PODL_PSE_PW_D_STATUS``         u32  power detection status of the
-                                                  PoDL PSE.
-  ``ETHTOOL_A_C33_PSE_ADMIN_STATE``          u32  Operational state of the PoE
-                                                  PSE functions.
-  ``ETHTOOL_A_C33_PSE_PW_D_STATUS``          u32  power detection status of the
-                                                  PoE PSE.
-  ``ETHTOOL_A_C33_PSE_PW_CLASS``             u32  power class of the PoE PSE.
-  ``ETHTOOL_A_C33_PSE_ACTUAL_PW``            u32  actual power drawn on the
-                                                  PoE PSE.
-  ``ETHTOOL_A_C33_PSE_EXT_STATE``            u32  power extended state of the
-                                                  PoE PSE.
-  ``ETHTOOL_A_C33_PSE_EXT_SUBSTATE``         u32  power extended substatus of
-                                                  the PoE PSE.
-  ======================================  ======  =============================
+  ==========================================  ======  =============================
+  ``ETHTOOL_A_PSE_HEADER``                    nested  reply header
+  ``ETHTOOL_A_PODL_PSE_ADMIN_STATE``             u32  Operational state of the PoDL
+                                                      PSE functions
+  ``ETHTOOL_A_PODL_PSE_PW_D_STATUS``             u32  power detection status of the
+                                                      PoDL PSE.
+  ``ETHTOOL_A_C33_PSE_ADMIN_STATE``              u32  Operational state of the PoE
+                                                      PSE functions.
+  ``ETHTOOL_A_C33_PSE_PW_D_STATUS``              u32  power detection status of the
+                                                      PoE PSE.
+  ``ETHTOOL_A_C33_PSE_PW_CLASS``                 u32  power class of the PoE PSE.
+  ``ETHTOOL_A_C33_PSE_ACTUAL_PW``                u32  actual power drawn on the
+                                                      PoE PSE.
+  ``ETHTOOL_A_C33_PSE_EXT_STATE``                u32  power extended state of the
+                                                      PoE PSE.
+  ``ETHTOOL_A_C33_PSE_EXT_SUBSTATE``             u32  power extended substatus of
+                                                      the PoE PSE.
+  ``ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT``           u32  currently configured power
+                                                      limit of the PoE PSE.
+  ``ETHTOOL_A_C33_PSE_PW_LIMIT_RANGES``       nested  Supported power limit
+                                                      configuration ranges.
+  ==========================================  ======  =============================
 
 When set, the optional ``ETHTOOL_A_PODL_PSE_ADMIN_STATE`` attribute identifies
 the operational state of the PoDL PSE functions.  The operational state of the
@@ -1809,6 +1813,16 @@ Possible values are:
 		  ethtool_c33_pse_ext_substate_power_not_available
 		  ethtool_c33_pse_ext_substate_short_detected
 
+When set, the optional ``ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT`` attribute
+identifies the C33 PSE power limit in mW.
+
+When set the optional ``ETHTOOL_A_C33_PSE_PW_LIMIT_RANGES`` nested attribute
+identifies the C33 PSE power limit ranges through
+``ETHTOOL_A_C33_PSE_PWR_VAL_LIMIT_RANGE_MIN`` and
+``ETHTOOL_A_C33_PSE_PWR_VAL_LIMIT_RANGE_MAX``.
+If the controller works with fixed classes, the min and max values will be
+equal.
+
 PSE_SET
 =======
 
@@ -1820,6 +1834,8 @@ Request contents:
   ``ETHTOOL_A_PSE_HEADER``                nested  request header
   ``ETHTOOL_A_PODL_PSE_ADMIN_CONTROL``       u32  Control PoDL PSE Admin state
   ``ETHTOOL_A_C33_PSE_ADMIN_CONTROL``        u32  Control PSE Admin state
+  ``ETHTOOL_A_C33_PSE_AVAIL_PWR_LIMIT``      u32  Control PoE PSE available
+                                                  power limit
   ======================================  ======  =============================
 
 When set, the optional ``ETHTOOL_A_PODL_PSE_ADMIN_CONTROL`` attribute is used
@@ -1830,6 +1846,18 @@ to control PoDL PSE Admin functions. This option is implementing
 The same goes for ``ETHTOOL_A_C33_PSE_ADMIN_CONTROL`` implementing
 ``IEEE 802.3-2022`` 30.9.1.2.1 acPSEAdminControl.
 
+When set, the optional ``ETHTOOL_A_C33_PSE_AVAIL_PWR_LIMIT`` attribute is
+used to control the available power value limit for C33 PSE in milliwatts.
+This attribute corresponds  to the `pse_available_power` variable described in
+``IEEE 802.3-2022`` 33.2.4.4 Variables  and `pse_avail_pwr` in 145.2.5.4
+Variables, which are described in power classes.
+
+It was decided to use milliwatts for this interface to unify it with other
+power monitoring interfaces, which also use milliwatts, and to align with
+various existing products that document power consumption in watts rather than
+classes. If power limit configuration based on classes is needed, the
+conversion can be done in user space, for example by ethtool.
+
 RSS_GET
 =======
 

include/linux/ethtool.h

@@ -1288,4 +1288,9 @@ struct ethtool_c33_pse_ext_state_info {
 		u32 __c33_pse_ext_substate;
 	};
 };
+
+struct ethtool_c33_pse_pw_limit_range {
+	u32 min;
+	u32 max;
+};
 #endif /* _LINUX_ETHTOOL_H */

include/uapi/linux/ethtool_netlink.h

@@ -930,6 +930,12 @@ enum {
 };
 
 /* Power Sourcing Equipment */
+enum {
+	ETHTOOL_A_C33_PSE_PW_LIMIT_UNSPEC,
+	ETHTOOL_A_C33_PSE_PW_LIMIT_MIN,	/* u32 */
+	ETHTOOL_A_C33_PSE_PW_LIMIT_MAX,	/* u32 */
+};
+
 enum {
 	ETHTOOL_A_PSE_UNSPEC,
 	ETHTOOL_A_PSE_HEADER,			/* nest - _A_HEADER_* */
@@ -943,6 +949,8 @@ enum {
 	ETHTOOL_A_C33_PSE_ACTUAL_PW,		/* u32 */
 	ETHTOOL_A_C33_PSE_EXT_STATE,		/* u32 */
 	ETHTOOL_A_C33_PSE_EXT_SUBSTATE,		/* u32 */
+	ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT,	/* u32 */
+	ETHTOOL_A_C33_PSE_PW_LIMIT_RANGES,	/* nest - _C33_PSE_PW_LIMIT_* */
 
 	/* add new constants above here */
 	__ETHTOOL_A_PSE_CNT,

net/ethtool/pse-pd.c

@@ -96,9 +96,46 @@ static int pse_reply_size(const struct ethnl_req_info *req_base,
 			/* _C33_PSE_EXT_SUBSTATE */
 			len += nla_total_size(sizeof(u32));
 	}
+	if (st->c33_avail_pw_limit > 0)
+		/* _C33_AVAIL_PSE_PW_LIMIT */
+		len += nla_total_size(sizeof(u32));
+	if (st->c33_pw_limit_nb_ranges > 0)
+		/* _C33_PSE_PW_LIMIT_RANGES */
+		len += st->c33_pw_limit_nb_ranges *
+		       (nla_total_size(0) +
+			nla_total_size(sizeof(u32)) * 2);
+
 	return len;
 }
 
+static int pse_put_pw_limit_ranges(struct sk_buff *skb,
+				   const struct pse_control_status *st)
+{
+	const struct ethtool_c33_pse_pw_limit_range *pw_limit_ranges;
+	int i;
+
+	pw_limit_ranges = st->c33_pw_limit_ranges;
+	for (i = 0; i < st->c33_pw_limit_nb_ranges; i++) {
+		struct nlattr *nest;
+
+		nest = nla_nest_start(skb, ETHTOOL_A_C33_PSE_PW_LIMIT_RANGES);
+		if (!nest)
+			return -EMSGSIZE;
+
+		if (nla_put_u32(skb, ETHTOOL_A_C33_PSE_PW_LIMIT_MIN,
+				pw_limit_ranges->min) ||
+		    nla_put_u32(skb, ETHTOOL_A_C33_PSE_PW_LIMIT_MAX,
+				pw_limit_ranges->max)) {
+			nla_nest_cancel(skb, nest);
+			return -EMSGSIZE;
+		}
+		nla_nest_end(skb, nest);
+		pw_limit_ranges++;
+	}
+
+	return 0;
+}
+
 static int pse_fill_reply(struct sk_buff *skb,
 			  const struct ethnl_req_info *req_base,
 			  const struct ethnl_reply_data *reply_base)
@@ -147,9 +184,25 @@ static int pse_fill_reply(struct sk_buff *skb,
 			return -EMSGSIZE;
 	}
 
+	if (st->c33_avail_pw_limit > 0 &&
+	    nla_put_u32(skb, ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT,
+			st->c33_avail_pw_limit))
+		return -EMSGSIZE;
+
+	if (st->c33_pw_limit_nb_ranges > 0 &&
+	    pse_put_pw_limit_ranges(skb, st))
+		return -EMSGSIZE;
+
 	return 0;
 }
 
+static void pse_cleanup_data(struct ethnl_reply_data *reply_base)
+{
+	const struct pse_reply_data *data = PSE_REPDATA(reply_base);
+
+	kfree(data->status.c33_pw_limit_ranges);
+}
+
 /* PSE_SET */
 
 const struct nla_policy ethnl_pse_set_policy[ETHTOOL_A_PSE_MAX + 1] = {
@@ -160,6 +213,7 @@ const struct nla_policy ethnl_pse_set_policy[ETHTOOL_A_PSE_MAX + 1] = {
 	[ETHTOOL_A_C33_PSE_ADMIN_CONTROL] =
 		NLA_POLICY_RANGE(NLA_U32, ETHTOOL_C33_PSE_ADMIN_STATE_DISABLED,
 				 ETHTOOL_C33_PSE_ADMIN_STATE_ENABLED),
+	[ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT] = { .type = NLA_U32 },
 };
 
 static int
@@ -202,19 +256,39 @@ static int
 ethnl_set_pse(struct ethnl_req_info *req_info, struct genl_info *info)
 {
 	struct net_device *dev = req_info->dev;
-	struct pse_control_config config = {};
 	struct nlattr **tb = info->attrs;
 	struct phy_device *phydev;
+	int ret = 0;
 
 	phydev = dev->phydev;
+
+	if (tb[ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT]) {
+		unsigned int pw_limit;
+
+		pw_limit = nla_get_u32(tb[ETHTOOL_A_C33_PSE_AVAIL_PW_LIMIT]);
+		ret = pse_ethtool_set_pw_limit(phydev->psec, info->extack,
+					       pw_limit);
+		if (ret)
+			return ret;
+	}
+
 	/* These values are already validated by the ethnl_pse_set_policy */
-	if (pse_has_podl(phydev->psec))
-		config.podl_admin_control = nla_get_u32(tb[ETHTOOL_A_PODL_PSE_ADMIN_CONTROL]);
-	if (pse_has_c33(phydev->psec))
-		config.c33_admin_control = nla_get_u32(tb[ETHTOOL_A_C33_PSE_ADMIN_CONTROL]);
+	if (tb[ETHTOOL_A_PODL_PSE_ADMIN_CONTROL] ||
+	    tb[ETHTOOL_A_C33_PSE_ADMIN_CONTROL]) {
+		struct pse_control_config config = {};
+
+		if (pse_has_podl(phydev->psec))
+			config.podl_admin_control = nla_get_u32(tb[ETHTOOL_A_PODL_PSE_ADMIN_CONTROL]);
+		if (pse_has_c33(phydev->psec))
+			config.c33_admin_control = nla_get_u32(tb[ETHTOOL_A_C33_PSE_ADMIN_CONTROL]);
+
+		ret = pse_ethtool_set_config(phydev->psec, info->extack,
+					     &config);
+		if (ret)
+			return ret;
+	}
 
-	/* Return errno directly - PSE has no notification */
-	return pse_ethtool_set_config(phydev->psec, info->extack, &config);
+	return ret;
 }
 
 const struct ethnl_request_ops ethnl_pse_request_ops = {
@@ -227,6 +301,7 @@ const struct ethnl_request_ops ethnl_pse_request_ops = {
 	.prepare_data		= pse_prepare_data,
 	.reply_size		= pse_reply_size,
 	.fill_reply		= pse_fill_reply,
+	.cleanup_data		= pse_cleanup_data,
 
 	.set_validate		= ethnl_set_pse_validate,
 	.set			= ethnl_set_pse,