[PATCH v4 2/3] net: ethtool: add KSZ87xx low-loss cable PHY tunables

[Fidelio Lawson]

Introduce vendor-specific PHY tunable identifiers to control the
KSZ87xx low-loss cable erratum handling through the ethtool PHY
tunable interface.

The following tunables are added:

- a boolean "short-cable" tunable, applying a documented and
  conservative preset intended for short or low-loss Ethernet cables;

- an integer LPF bandwidth tunable, allowing advanced adjustment of the
  receiver low-pass filter bandwidth;

- an integer DSP EQ initial value tunable, allowing advanced tuning of
  the PHY equalizer initialization.

The actual behavior is implemented by the corresponding PHY and switch
drivers.

Signed-off-by: Fidelio Lawson <fidelio.lawson@xxxxxxxxxx>
---
 include/uapi/linux/ethtool.h | 3 +++
 net/ethtool/common.c         | 3 +++
 net/ethtool/ioctl.c          | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index b74b80508553..081d8f2191b6 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -291,6 +291,9 @@ enum phy_tunable_id {
 	ETHTOOL_PHY_DOWNSHIFT,
 	ETHTOOL_PHY_FAST_LINK_DOWN,
 	ETHTOOL_PHY_EDPD,
+	ETHTOOL_PHY_SHORT_CABLE_PRESET,
+	ETHTOOL_PHY_LPF_BW,
+	ETHTOOL_PHY_DSP_EQ_INIT_VALUE,
 	/*
 	 * Add your fresh new phy tunable attribute above and remember to update
 	 * phy_tunable_strings[] in net/ethtool/common.c
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index e252cf20c22f..9c2fe5b626d6 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -101,6 +101,9 @@ phy_tunable_strings[__ETHTOOL_PHY_TUNABLE_COUNT][ETH_GSTRING_LEN] = {
 	[ETHTOOL_PHY_DOWNSHIFT]	= "phy-downshift",
 	[ETHTOOL_PHY_FAST_LINK_DOWN] = "phy-fast-link-down",
 	[ETHTOOL_PHY_EDPD]	= "phy-energy-detect-power-down",
+	[ETHTOOL_PHY_SHORT_CABLE_PRESET] = "phy-short-cable-preset",
+	[ETHTOOL_PHY_LPF_BW]	= "phy-lpf-bandwidth",
+	[ETHTOOL_PHY_DSP_EQ_INIT_VALUE] = "phy-dsp-eq-init-value",
 };
 
 #define __LINK_MODE_NAME(speed, type, duplex) \
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index ff4b4780d6af..5b66e4a96f67 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -3109,6 +3109,9 @@ static int ethtool_phy_tunable_valid(const struct ethtool_tunable *tuna)
 	switch (tuna->id) {
 	case ETHTOOL_PHY_DOWNSHIFT:
 	case ETHTOOL_PHY_FAST_LINK_DOWN:
+	case ETHTOOL_PHY_SHORT_CABLE_PRESET:
+	case ETHTOOL_PHY_LPF_BW:
+	case ETHTOOL_PHY_DSP_EQ_INIT_VALUE:
 		if (tuna->len != sizeof(u8) ||
 		    tuna->type_id != ETHTOOL_TUNABLE_U8)
 			return -EINVAL;

-- 
2.53.0