ethtool: Introduce a method for getting time stamping capabilities.

This commit adds a new ethtool ioctl that exposes the SO_TIMESTAMPING
capabilities of a network interface. In addition, user space programs
can use this ioctl to discover the PTP Hardware Clock (PHC) device
associated with the interface.

Since software receive time stamps are handled by the stack, the generic
ethtool code can answer the query correctly in case the MAC or PHY
drivers lack special time stamping features.

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

1 files changed, 45 insertions, 3 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 6d6d7d2..a723b13 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -17,6 +17,8 @@
 #include <linux/errno.h>
 #include <linux/ethtool.h>
 #include <linux/netdevice.h>
+#include <linux/net_tstamp.h>
+#include <linux/phy.h>
 #include <linux/bitops.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
@@ -1278,6 +1280,40 @@ out:
 	return ret;
 }
 
+static int ethtool_get_ts_info(struct net_device *dev, void __user *useraddr)
+{
+	int err = 0;
+	struct ethtool_ts_info info;
+	const struct ethtool_ops *ops = dev->ethtool_ops;
+	struct phy_device *phydev = dev->phydev;
+
+	memset(&info, 0, sizeof(info));
+	info.cmd = ETHTOOL_GET_TS_INFO;
+
+	if (phydev && phydev->drv && phydev->drv->ts_info) {
+
+		err = phydev->drv->ts_info(phydev, &info);
+
+	} else if (dev->ethtool_ops && dev->ethtool_ops->get_ts_info) {
+
+		err = ops->get_ts_info(dev, &info);
+
+	} else {
+		info.so_timestamping =
+			SOF_TIMESTAMPING_RX_SOFTWARE |
+			SOF_TIMESTAMPING_SOFTWARE;
+		info.phc_index = -1;
+	}
+
+	if (err)
+		return err;
+
+	if (copy_to_user(useraddr, &info, sizeof(info)))
+		err = -EFAULT;
+
+	return err;
+}
+
 /* The main entry point in this file.  Called from net/core/dev.c */
 
 int dev_ethtool(struct net *net, struct ifreq *ifr)
@@ -1295,11 +1331,13 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 		return -EFAULT;
 
 	if (!dev->ethtool_ops) {
-		/* ETHTOOL_GDRVINFO does not require any driver support.
-		 * It is also unprivileged and does not change anything,
-		 * so we can take a shortcut to it. */
+		/* A few commands do not require any driver support,
+		 * are unprivileged, and do not change anything, so we
+		 * can take a shortcut to them. */
 		if (ethcmd == ETHTOOL_GDRVINFO)
 			return ethtool_get_drvinfo(dev, useraddr);
+		else if (ethcmd == ETHTOOL_GET_TS_INFO)
+			return ethtool_get_ts_info(dev, useraddr);
 		else
 			return -EOPNOTSUPP;
 	}
@@ -1330,6 +1368,7 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_GRXCLSRULE:
 	case ETHTOOL_GRXCLSRLALL:
 	case ETHTOOL_GFEATURES:
+	case ETHTOOL_GET_TS_INFO:
 		break;
 	default:
 		if (!capable(CAP_NET_ADMIN))
@@ -1496,6 +1535,9 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
 	case ETHTOOL_GET_DUMP_DATA:
 		rc = ethtool_get_dump_data(dev, useraddr);
 		break;
+	case ETHTOOL_GET_TS_INFO:
+		rc = ethtool_get_ts_info(dev, useraddr);
+		break;
 	default:
 		rc = -EOPNOTSUPP;
 	}