[PATCH net-next 1/2] ethtool: add PHY Fast Link Down support

[Heiner Kallweit]

This adds support for Fast Link Down as new PHY tunable.
Fast Link Down reduces the time until a link down event is reported
for 1000BaseT. According to the standard it's 750ms what is too long
for several use cases.

Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
---
 include/uapi/linux/ethtool.h | 4 ++++
 net/core/ethtool.c           | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 3652b239d..2c7136adc 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -252,9 +252,13 @@ struct ethtool_tunable {
 #define DOWNSHIFT_DEV_DEFAULT_COUNT    0xff
 #define DOWNSHIFT_DEV_DISABLE          0
 
+#define ETHTOOL_PHY_FAST_LINK_DOWN_ON  0
+#define ETHTOOL_PHY_FAST_LINK_DOWN_OFF 0xff
+
 enum phy_tunable_id {
        ETHTOOL_PHY_ID_UNSPEC,
        ETHTOOL_PHY_DOWNSHIFT,
+       ETHTOOL_PHY_FAST_LINK_DOWN,
        /*
         * Add your fresh new phy tunable attribute above and remember to update
         * phy_tunable_strings[] in net/core/ethtool.c
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index b1eb32419..387d67eb7 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -136,6 +136,7 @@ static const char
 phy_tunable_strings[__ETHTOOL_PHY_TUNABLE_COUNT][ETH_GSTRING_LEN] = {
        [ETHTOOL_ID_UNSPEC]     = "Unspec",
        [ETHTOOL_PHY_DOWNSHIFT] = "phy-downshift",
+       [ETHTOOL_PHY_FAST_LINK_DOWN] = "phy-fast-link-down",
 };
 
 static int ethtool_get_features(struct net_device *dev, void __user *useraddr)
@@ -2432,6 +2433,7 @@ static int ethtool_phy_tunable_valid(const struct 
ethtool_tunable *tuna)
 {
        switch (tuna->id) {
        case ETHTOOL_PHY_DOWNSHIFT:
+       case ETHTOOL_PHY_FAST_LINK_DOWN:
                if (tuna->len != sizeof(u8) ||
                    tuna->type_id != ETHTOOL_TUNABLE_U8)
                        return -EINVAL;
-- 
2.21.0