[PATCH RFC v2 1/6] ethtool: add interface to read Tx hardware timestamping statistics

[Rahul Rameshbabu <rrameshbabu@nvidia.com>]

Multiple network devices that support hardware timestamping appear to have
common behavior with regards to timestamp handling. Implement common Tx
hardware timestamping statistics in a tx_stats struct_group. Common Rx
hardware timestamping statistics can subsequently be implemented in a
rx_stats struct_group for ethtool_ts_stats.

Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
---
 Documentation/netlink/specs/ethtool.yaml | 20 +++++++++
 include/linux/ethtool.h                  | 21 ++++++++++
 include/uapi/linux/ethtool_netlink.h     | 15 +++++++
 net/ethtool/tsinfo.c                     | 52 +++++++++++++++++++++++-
 4 files changed, 107 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
index 197208f419dc..f99b003c78c0 100644
--- a/Documentation/netlink/specs/ethtool.yaml
+++ b/Documentation/netlink/specs/ethtool.yaml
@@ -559,6 +559,21 @@ attribute-sets:
       -
         name: tx-lpi-timer
         type: u32
+  -
+    name: ts-stat
+    attributes:
+      -
+        name: pad
+        type: pad
+      -
+        name: tx-pkts
+        type: u64
+      -
+        name: tx-lost
+        type: u64
+      -
+        name: tx-err
+        type: u64
   -
     name: tsinfo
     attributes:
@@ -581,6 +596,10 @@ attribute-sets:
       -
         name: phc-index
         type: u32
+      -
+        name: stats
+        type: nest
+        nested-attributes: ts-stat
   -
     name: cable-result
     attributes:
@@ -1388,6 +1407,7 @@ operations:
             - tx-types
             - rx-filters
             - phc-index
+            - stats
       dump: *tsinfo-get-op
     -
       name: cable-test-act
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index b90c33607594..a1704938a6fb 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -483,6 +483,24 @@ struct ethtool_rmon_stats {
 	);
 };
 
+/**
+ * struct ethtool_ts_stats - HW timestamping statistics
+ * @tx_stats: struct group for TX HW timestamping
+ *	@pkts: Number of packets successfully timestamped by the queried
+ *	      layer.
+ *	@lost: Number of packet timestamps that failed to get applied on a
+ *	      packet by the queried layer.
+ *	@err: Number of timestamping errors that occurred on the queried
+ *	     layer.
+ */
+struct ethtool_ts_stats {
+	struct_group(tx_stats,
+		u64 pkts;
+		u64 lost;
+		u64 err;
+	);
+};
+
 #define ETH_MODULE_EEPROM_PAGE_LEN	128
 #define ETH_MODULE_MAX_I2C_ADDRESS	0x7f
 
@@ -759,6 +777,7 @@ struct ethtool_rxfh_param {
  *	It may be called with RCU, or rtnl or reference on the device.
  *	Drivers supporting transmit time stamps in software should set this to
  *	ethtool_op_get_ts_info().
+ * @get_ts_stats: Query the device hardware timestamping statistics.
  * @get_module_info: Get the size and type of the eeprom contained within
  *	a plug-in module.
  * @get_module_eeprom: Get the eeprom information from the plug-in module
@@ -901,6 +920,8 @@ struct ethtool_ops {
 				 struct ethtool_dump *, void *);
 	int	(*set_dump)(struct net_device *, struct ethtool_dump *);
 	int	(*get_ts_info)(struct net_device *, struct ethtool_ts_info *);
+	void	(*get_ts_stats)(struct net_device *dev,
+				struct ethtool_ts_stats *ts_stats);
 	int     (*get_module_info)(struct net_device *,
 				   struct ethtool_modinfo *);
 	int     (*get_module_eeprom)(struct net_device *,
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 3f89074aa06c..046a78d9421d 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -478,12 +478,27 @@ enum {
 	ETHTOOL_A_TSINFO_TX_TYPES,			/* bitset */
 	ETHTOOL_A_TSINFO_RX_FILTERS,			/* bitset */
 	ETHTOOL_A_TSINFO_PHC_INDEX,			/* u32 */
+	ETHTOOL_A_TSINFO_STATS,				/* nest - _A_TSINFO_STAT */
 
 	/* add new constants above here */
 	__ETHTOOL_A_TSINFO_CNT,
 	ETHTOOL_A_TSINFO_MAX = (__ETHTOOL_A_TSINFO_CNT - 1)
 };
 
+enum {
+	ETHTOOL_A_TS_STAT_UNSPEC,
+	ETHTOOL_A_TS_STAT_PAD,
+
+	ETHTOOL_A_TS_STAT_TX_PKT,			/* array, u64 */
+	ETHTOOL_A_TS_STAT_TX_LOST,			/* array, u64 */
+	ETHTOOL_A_TS_STAT_TX_ERR,			/* array, u64 */
+
+	/* add new constants above here */
+	__ETHTOOL_A_TS_STAT_CNT,
+	ETHTOOL_A_TS_STAT_MAX = (__ETHTOOL_A_TS_STAT_CNT - 1)
+
+};
+
 /* PHC VCLOCKS */
 
 enum {
diff --git a/net/ethtool/tsinfo.c b/net/ethtool/tsinfo.c
index 9daed0aab162..0d1370ded122 100644
--- a/net/ethtool/tsinfo.c
+++ b/net/ethtool/tsinfo.c
@@ -13,14 +13,18 @@ struct tsinfo_req_info {
 struct tsinfo_reply_data {
 	struct ethnl_reply_data		base;
 	struct ethtool_ts_info		ts_info;
+	struct ethtool_ts_stats		stats;
 };
 
 #define TSINFO_REPDATA(__reply_base) \
 	container_of(__reply_base, struct tsinfo_reply_data, base)
 
+#define ETHTOOL_TS_STAT_CNT \
+	(__ETHTOOL_A_TS_STAT_CNT - (ETHTOOL_A_TS_STAT_PAD + 1))
+
 const struct nla_policy ethnl_tsinfo_get_policy[] = {
 	[ETHTOOL_A_TSINFO_HEADER]		=
-		NLA_POLICY_NESTED(ethnl_header_policy),
+		NLA_POLICY_NESTED(ethnl_header_policy_stats),
 };
 
 static int tsinfo_prepare_data(const struct ethnl_req_info *req_base,
@@ -34,6 +38,12 @@ static int tsinfo_prepare_data(const struct ethnl_req_info *req_base,
 	ret = ethnl_ops_begin(dev);
 	if (ret < 0)
 		return ret;
+	if (req_base->flags & ETHTOOL_FLAG_STATS &&
+	    dev->ethtool_ops->get_ts_stats) {
+		ethtool_stats_init((u64 *)&data->stats,
+				   sizeof(data->stats) / sizeof(u64));
+		dev->ethtool_ops->get_ts_stats(dev, &data->stats);
+	}
 	ret = __ethtool_get_ts_info(dev, &data->ts_info);
 	ethnl_ops_complete(dev);
 
@@ -79,10 +89,47 @@ static int tsinfo_reply_size(const struct ethnl_req_info *req_base,
 	}
 	if (ts_info->phc_index >= 0)
 		len += nla_total_size(sizeof(u32));	/* _TSINFO_PHC_INDEX */
+	if (req_base->flags & ETHTOOL_FLAG_STATS)
+		len += nla_total_size(0) + /* _TSINFO_STATS */
+		       nla_total_size_64bit(sizeof(u64)) * ETHTOOL_TS_STAT_CNT;
 
 	return len;
 }
 
+static int tsinfo_put_stat(struct sk_buff *skb, u64 val, u16 attrtype)
+{
+	if (val == ETHTOOL_STAT_NOT_SET)
+		return 0;
+	if (nla_put_u64_64bit(skb, attrtype, val, ETHTOOL_A_TS_STAT_PAD))
+		return -EMSGSIZE;
+	return 0;
+}
+
+static int tsinfo_put_stats(struct sk_buff *skb,
+			    const struct ethtool_ts_stats *stats)
+{
+	struct nlattr *nest;
+
+	nest = nla_nest_start(skb, ETHTOOL_A_TSINFO_STATS);
+	if (!nest)
+		return -EMSGSIZE;
+
+	if (tsinfo_put_stat(skb, stats->tx_stats.pkts,
+			    ETHTOOL_A_TS_STAT_TX_PKT) ||
+	    tsinfo_put_stat(skb, stats->tx_stats.lost,
+			    ETHTOOL_A_TS_STAT_TX_LOST) ||
+	    tsinfo_put_stat(skb, stats->tx_stats.err,
+			    ETHTOOL_A_TS_STAT_TX_ERR))
+		goto err_cancel;
+
+	nla_nest_end(skb, nest);
+	return 0;
+
+err_cancel:
+	nla_nest_cancel(skb, nest);
+	return -EMSGSIZE;
+}
+
 static int tsinfo_fill_reply(struct sk_buff *skb,
 			     const struct ethnl_req_info *req_base,
 			     const struct ethnl_reply_data *reply_base)
@@ -119,6 +166,9 @@ static int tsinfo_fill_reply(struct sk_buff *skb,
 	if (ts_info->phc_index >= 0 &&
 	    nla_put_u32(skb, ETHTOOL_A_TSINFO_PHC_INDEX, ts_info->phc_index))
 		return -EMSGSIZE;
+	if (req_base->flags & ETHTOOL_FLAG_STATS &&
+	    tsinfo_put_stats(skb, &data->stats))
+		return -EMSGSIZE;
 
 	return 0;
 }
-- 
2.42.0