[RFC PATCH net-next 4/7] net: ethtool: add a netlink command to list PHYs

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Introduce a new netlink message that lists all PHYs on a given interface
at a given time.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 include/uapi/linux/ethtool_netlink.h | 13 ++++
 net/ethtool/Makefile                 |  2 +-
 net/ethtool/netlink.c                | 10 +++
 net/ethtool/netlink.h                |  2 +
 net/ethtool/phy_list.c               | 99 ++++++++++++++++++++++++++++
 5 files changed, 125 insertions(+), 1 deletion(-)
 create mode 100644 net/ethtool/phy_list.c

diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 73e2c10dc2cc..b2a0d21fdd8e 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -57,6 +57,7 @@ enum {
 	ETHTOOL_MSG_PLCA_GET_STATUS,
 	ETHTOOL_MSG_MM_GET,
 	ETHTOOL_MSG_MM_SET,
+	ETHTOOL_MSG_PHY_LIST_GET,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_USER_CNT,
@@ -109,6 +110,7 @@ enum {
 	ETHTOOL_MSG_PLCA_NTF,
 	ETHTOOL_MSG_MM_GET_REPLY,
 	ETHTOOL_MSG_MM_NTF,
+	ETHTOOL_MSG_PHY_LIST_GET_REPLY,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,
@@ -975,6 +977,17 @@ enum {
 	ETHTOOL_A_MM_MAX = (__ETHTOOL_A_MM_CNT - 1)
 };
 
+enum {
+	ETHTOOL_A_PHY_LIST_UNSPEC,
+	ETHTOOL_A_PHY_LIST_HEADER,			/* nest - _A_HEADER_* */
+	ETHTOOL_A_PHY_LIST_COUNT,			/* u8 */
+	ETHTOOL_A_PHY_LIST_INDEX,			/* array, u32 */
+
+	/* add new constants above here */
+	__ETHTOOL_A_PHY_LIST_CNT,
+	ETHTOOL_A_PHY_LIST_MAX = (__ETHTOOL_A_PHY_LIST_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 504f954a1b28..a182c0dbbb9d 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 mm.o \
-		   module.o pse-pd.o plca.o mm.o
+		   module.o pse-pd.o plca.o mm.o phy_list.o
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 3bbd5afb7b31..60b66b78055e 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -306,6 +306,7 @@ ethnl_default_requests[__ETHTOOL_MSG_USER_CNT] = {
 	[ETHTOOL_MSG_PLCA_GET_STATUS]	= &ethnl_plca_status_request_ops,
 	[ETHTOOL_MSG_MM_GET]		= &ethnl_mm_request_ops,
 	[ETHTOOL_MSG_MM_SET]		= &ethnl_mm_request_ops,
+	[ETHTOOL_MSG_PHY_LIST_GET]	= &ethnl_phy_list_request_ops,
 };
 
 static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
@@ -1128,6 +1129,15 @@ static const struct genl_ops ethtool_genl_ops[] = {
 		.policy = ethnl_mm_set_policy,
 		.maxattr = ARRAY_SIZE(ethnl_mm_set_policy) - 1,
 	},
+	{
+		.cmd	= ETHTOOL_MSG_PHY_LIST_GET,
+		.doit	= ethnl_default_doit,
+		.start	= ethnl_default_start,
+		.dumpit	= ethnl_default_dumpit,
+		.done	= ethnl_default_done,
+		.policy = ethnl_phy_list_get_policy,
+		.maxattr = ARRAY_SIZE(ethnl_phy_list_get_policy) - 1,
+	},
 };
 
 static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index 9a333a8d04c1..76859d8fbce0 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -395,6 +395,7 @@ 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 ethnl_request_ops ethnl_mm_request_ops;
+extern const struct ethnl_request_ops ethnl_phy_list_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];
@@ -441,6 +442,7 @@ 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];
 extern const struct nla_policy ethnl_mm_get_policy[ETHTOOL_A_MM_HEADER + 1];
 extern const struct nla_policy ethnl_mm_set_policy[ETHTOOL_A_MM_MAX + 1];
+extern const struct nla_policy ethnl_phy_list_get_policy[ETHTOOL_A_PHY_LIST_HEADER + 1];
 
 int ethnl_set_features(struct sk_buff *skb, struct genl_info *info);
 int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info);
diff --git a/net/ethtool/phy_list.c b/net/ethtool/phy_list.c
new file mode 100644
index 000000000000..689d08637391
--- /dev/null
+++ b/net/ethtool/phy_list.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Bootlin
+ *
+ * Ethtool netlink operations for Ethernet PHY specific operations
+ */
+#include "common.h"
+#include "netlink.h"
+
+#include <linux/phy.h>
+#include <linux/phy_ns.h>
+
+struct phy_list_req_info {
+	struct ethnl_req_info		base;
+};
+
+#define PHY_MAX_ENTRIES	16
+
+struct phy_list_reply_data {
+	struct ethnl_reply_data		base;
+	u8 n_phys;
+	u32 phy_indices[PHY_MAX_ENTRIES];
+};
+
+#define PHY_LIST_REPDATA(__reply_base) \
+	container_of(__reply_base, struct phy_list_reply_data, base)
+
+const struct nla_policy ethnl_phy_list_get_policy[ETHTOOL_A_PHY_LIST_HEADER + 1] = {
+	[ETHTOOL_A_PHY_LIST_HEADER] = NLA_POLICY_NESTED(ethnl_header_policy_stats),
+};
+
+static int phy_list_prepare_data(const struct ethnl_req_info *req_base,
+				 struct ethnl_reply_data *reply_base,
+				 struct genl_info *info)
+{
+	struct phy_list_reply_data *data = PHY_LIST_REPDATA(reply_base);
+	struct net_device *dev = reply_base->dev;
+	struct phy_namespace *phy_ns = &dev->phy_ns;
+	struct phy_device *phydev;
+	int ret;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+
+	data->n_phys = 0;
+
+	mutex_lock(&phy_ns->ns_lock);
+	list_for_each_entry(phydev, &phy_ns->phys, node)
+		data->phy_indices[data->n_phys++] = phydev->phyindex;
+	mutex_unlock(&phy_ns->ns_lock);
+
+	ethnl_ops_complete(dev);
+
+	return ret;
+}
+
+static int phy_list_reply_size(const struct ethnl_req_info *req_base,
+			       const struct ethnl_reply_data *reply_base)
+{
+	const struct phy_list_reply_data *data = PHY_LIST_REPDATA(reply_base);
+	int len = 0;
+
+	len += nla_total_size(sizeof(u8)); /* _PHY_LIST_COUNT */
+	len += nla_total_size(data->n_phys * sizeof(u32)); /* Array of _PHY_LIST_INDEX */
+
+	return len;
+}
+
+static int phy_list_fill_reply(struct sk_buff *skb,
+			       const struct ethnl_req_info *req_base,
+			       const struct ethnl_reply_data *reply_base)
+{
+	const struct phy_list_reply_data *data = PHY_LIST_REPDATA(reply_base);
+
+	if (nla_put_u8(skb, ETHTOOL_A_PHY_LIST_COUNT, data->n_phys))
+		return -EMSGSIZE;
+
+	if (!data->n_phys)
+		return 0;
+
+	if (nla_put(skb, ETHTOOL_A_PHY_LIST_INDEX, sizeof(u32) * data->n_phys,
+		    data->phy_indices))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+const struct ethnl_request_ops ethnl_phy_list_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_PHY_LIST_GET,
+	.reply_cmd		= ETHTOOL_MSG_PHY_LIST_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_PHY_LIST_HEADER,
+	.req_info_size		= sizeof(struct phy_list_req_info),
+	.reply_data_size	= sizeof(struct phy_list_reply_data),
+
+	.prepare_data		= phy_list_prepare_data,
+	.reply_size		= phy_list_reply_size,
+	.fill_reply		= phy_list_fill_reply,
+};
-- 
2.41.0