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>

3 files changed, 76 insertions, 3 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index e1d9e0ede309..1769714447b3 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -726,6 +726,29 @@ struct ethtool_sfeatures {
         struct ethtool_set_features_block features[0];
 };
 
+/**
+ * struct ethtool_ts_info - holds a device's timestamping and PHC association
+ * @cmd: command number = %ETHTOOL_GET_TS_INFO
+ * @so_timestamping: bit mask of the sum of the supported SO_TIMESTAMPING flags
+ * @phc_index: device index of the associated PHC, or -1 if there is none
+ * @tx_types: bit mask of the supported hwtstamp_tx_types enumeration values
+ * @rx_filters: bit mask of the supported hwtstamp_rx_filters enumeration values
+ *
+ * The bits in the 'tx_types' and 'rx_filters' fields correspond to
+ * the 'hwtstamp_tx_types' and 'hwtstamp_rx_filters' enumeration values,
+ * respectively.  For example, if the device supports HWTSTAMP_TX_ON,
+ * then (1 << HWTSTAMP_TX_ON) in 'tx_types' will be set.
+ */
+struct ethtool_ts_info {
+        __u32   cmd;
+        __u32   so_timestamping;
+        __s32   phc_index;
+        __u32   tx_types;
+        __u32   tx_reserved[3];
+        __u32   rx_filters;
+        __u32   rx_reserved[3];
+};
+
 /*
  * %ETHTOOL_SFEATURES changes features present in features[].valid to the
  * values of corresponding bits in features[].requested. Bits in .requested
@@ -893,6 +916,9 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
  *                 and flag of the device.
  * @get_dump_data: Get dump data.
  * @set_dump: Set dump specific flags to the device.
+ * @get_ts_info: Get the time stamping and PTP hardware clock capabilities.
+ *      Drivers supporting transmit time stamps in software should set this to
+ *      ethtool_op_get_ts_info().
  *
  * All operations are optional (i.e. the function pointer may be set
  * to %NULL) and callers must take this into account.  Callers must
@@ -955,6 +981,7 @@ struct ethtool_ops {
         int     (*get_dump_data)(struct net_device *,
                                  struct ethtool_dump *, void *);
         int     (*set_dump)(struct net_device *, struct ethtool_dump *);
+        int     (*get_ts_info)(struct net_device *, struct ethtool_ts_info *);
 
 };
 #endif /* __KERNEL__ */
@@ -1029,6 +1056,7 @@ struct ethtool_ops {
 #define ETHTOOL_SET_DUMP        0x0000003e /* Set dump settings */
 #define ETHTOOL_GET_DUMP_FLAG   0x0000003f /* Get dump settings */
 #define ETHTOOL_GET_DUMP_DATA   0x00000040 /* Get dump data */
+#define ETHTOOL_GET_TS_INFO     0x00000041 /* Get time stamping and PHC info */
 
 /* compatibility with older code */
 #define SPARC_ETH_GSET          ETHTOOL_GSET
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 6fe0a37d4abf..f092032f1c98 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -412,6 +412,9 @@ struct phy_driver {
         /* Clears up any memory if needed */
         void (*remove)(struct phy_device *phydev);
 
+        /* Handles ethtool queries for hardware time stamping. */
+        int (*ts_info)(struct phy_device *phydev, struct ethtool_ts_info *ti);
+
         /* Handles SIOCSHWTSTAMP ioctl for hardware time stamping. */
         int  (*hwtstamp)(struct phy_device *phydev, struct ifreq *ifr);
 
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 6d6d7d25caaa..a723b1321691 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;
         }