ethtool: provide UAPI for PHY master/slave configuration.

This UAPI is needed for BroadR-Reach 100BASE-T1 devices. Due to lack of
auto-negotiation support, we needed to be able to configure the
MASTER-SLAVE role of the port manually or from an application in user
space.

The same UAPI can be used for 1000BASE-T or MultiGBASE-T devices to
force MASTER or SLAVE role. See IEEE 802.3-2018:
22.2.4.3.7 MASTER-SLAVE control register (Register 9)
22.2.4.3.8 MASTER-SLAVE status register (Register 10)
40.5.2 MASTER-SLAVE configuration resolution
45.2.1.185.1 MASTER-SLAVE config value (1.2100.14)
45.2.7.10 MultiGBASE-T AN control 1 register (Register 7.32)

The MASTER-SLAVE role affects the clock configuration:

-------------------------------------------------------------------------------
When the  PHY is configured as MASTER, the PMA Transmit function shall
source TX_TCLK from a local clock source. When configured as SLAVE, the
PMA Transmit function shall source TX_TCLK from the clock recovered from
data stream provided by MASTER.

iMX6Q                     KSZ9031                XXX
------\                /-----------\        /------------\
      |                |           |        |            |
 MAC  |<----RGMII----->| PHY Slave |<------>| PHY Master |
      |<--- 125 MHz ---+-<------/  |        | \          |
------/                \-----------/        \------------/
                                               ^
                                                \-TX_TCLK

-------------------------------------------------------------------------------

Since some clock or link related issues are only reproducible in a
specific MASTER-SLAVE-role, MAC and PHY configuration, it is beneficial
to provide generic (not 100BASE-T1 specific) interface to the user space
for configuration flexibility and trouble shooting.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 59 insertions, 0 deletions

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 226d5ecdd567..52102ab1709b 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -552,6 +552,8 @@ static int ethtool_get_link_ksettings(struct net_device *dev,
 	link_ksettings.base.cmd = ETHTOOL_GLINKSETTINGS;
 	link_ksettings.base.link_mode_masks_nwords
 		= __ETHTOOL_LINK_MODE_MASK_NU32;
+	link_ksettings.base.master_slave_cfg = MASTER_SLAVE_CFG_UNSUPPORTED;
+	link_ksettings.base.master_slave_state = MASTER_SLAVE_STATE_UNSUPPORTED;
 
 	return store_link_ksettings_for_user(useraddr, &link_ksettings);
 }
@@ -589,6 +591,10 @@ static int ethtool_set_link_ksettings(struct net_device *dev,
 	    != link_ksettings.base.link_mode_masks_nwords)
 		return -EINVAL;
 
+	if (link_ksettings.base.master_slave_cfg ||
+	    link_ksettings.base.master_slave_state)
+		return -EINVAL;
+
 	err = dev->ethtool_ops->set_link_ksettings(dev, &link_ksettings);
 	if (err >= 0) {
 		ethtool_notify(dev, ETHTOOL_MSG_LINKINFO_NTF, NULL);
diff --git a/net/ethtool/linkmodes.c b/net/ethtool/linkmodes.c
index 452608c6d856..fd4f3e58c6f6 100644
--- a/net/ethtool/linkmodes.c
+++ b/net/ethtool/linkmodes.c
@@ -27,6 +27,8 @@ linkmodes_get_policy[ETHTOOL_A_LINKMODES_MAX + 1] = {
 	[ETHTOOL_A_LINKMODES_PEER]		= { .type = NLA_REJECT },
 	[ETHTOOL_A_LINKMODES_SPEED]		= { .type = NLA_REJECT },
 	[ETHTOOL_A_LINKMODES_DUPLEX]		= { .type = NLA_REJECT },
+	[ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG]	= { .type = NLA_REJECT },
+	[ETHTOOL_A_LINKMODES_MASTER_SLAVE_STATE]	= { .type = NLA_REJECT },
 };
 
 static int linkmodes_prepare_data(const struct ethnl_req_info *req_base,
@@ -63,6 +65,7 @@ static int linkmodes_reply_size(const struct ethnl_req_info *req_base,
 {
 	const struct linkmodes_reply_data *data = LINKMODES_REPDATA(reply_base);
 	const struct ethtool_link_ksettings *ksettings = &data->ksettings;
+	const struct ethtool_link_settings *lsettings = &ksettings->base;
 	bool compact = req_base->flags & ETHTOOL_FLAG_COMPACT_BITSETS;
 	int len, ret;
 
@@ -86,6 +89,12 @@ static int linkmodes_reply_size(const struct ethnl_req_info *req_base,
 		len += ret;
 	}
 
+	if (lsettings->master_slave_cfg != MASTER_SLAVE_CFG_UNSUPPORTED)
+		len += nla_total_size(sizeof(u8));
+
+	if (lsettings->master_slave_state != MASTER_SLAVE_STATE_UNSUPPORTED)
+		len += nla_total_size(sizeof(u8));
+
 	return len;
 }
 
@@ -122,6 +131,16 @@ static int linkmodes_fill_reply(struct sk_buff *skb,
 	    nla_put_u8(skb, ETHTOOL_A_LINKMODES_DUPLEX, lsettings->duplex))
 		return -EMSGSIZE;
 
+	if (lsettings->master_slave_cfg != MASTER_SLAVE_CFG_UNSUPPORTED &&
+	    nla_put_u8(skb, ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG,
+		       lsettings->master_slave_cfg))
+		return -EMSGSIZE;
+
+	if (lsettings->master_slave_state != MASTER_SLAVE_STATE_UNSUPPORTED &&
+	    nla_put_u8(skb, ETHTOOL_A_LINKMODES_MASTER_SLAVE_STATE,
+		       lsettings->master_slave_state))
+		return -EMSGSIZE;
+
 	return 0;
 }
 
@@ -249,6 +268,8 @@ linkmodes_set_policy[ETHTOOL_A_LINKMODES_MAX + 1] = {
 	[ETHTOOL_A_LINKMODES_PEER]		= { .type = NLA_REJECT },
 	[ETHTOOL_A_LINKMODES_SPEED]		= { .type = NLA_U32 },
 	[ETHTOOL_A_LINKMODES_DUPLEX]		= { .type = NLA_U8 },
+	[ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG]	= { .type = NLA_U8 },
+	[ETHTOOL_A_LINKMODES_MASTER_SLAVE_STATE]	= { .type = NLA_REJECT },
 };
 
 /* Set advertised link modes to all supported modes matching requested speed
@@ -287,14 +308,45 @@ static bool ethnl_auto_linkmodes(struct ethtool_link_ksettings *ksettings,
 			     __ETHTOOL_LINK_MODE_MASK_NBITS);
 }
 
+static bool ethnl_validate_master_slave_cfg(u8 cfg)
+{
+	switch (cfg) {
+	case MASTER_SLAVE_CFG_MASTER_PREFERRED:
+	case MASTER_SLAVE_CFG_SLAVE_PREFERRED:
+	case MASTER_SLAVE_CFG_MASTER_FORCE:
+	case MASTER_SLAVE_CFG_SLAVE_FORCE:
+		return true;
+	}
+
+	return false;
+}
+
 static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb,
 				  struct ethtool_link_ksettings *ksettings,
 				  bool *mod)
 {
 	struct ethtool_link_settings *lsettings = &ksettings->base;
 	bool req_speed, req_duplex;
+	const struct nlattr *master_slave_cfg;
 	int ret;
 
+	master_slave_cfg = tb[ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG];
+	if (master_slave_cfg) {
+		u8 cfg = nla_get_u8(master_slave_cfg);
+
+		if (lsettings->master_slave_cfg == MASTER_SLAVE_CFG_UNSUPPORTED) {
+			NL_SET_ERR_MSG_ATTR(info->extack, master_slave_cfg,
+					    "master/slave configuration not supported by device");
+			return -EOPNOTSUPP;
+		}
+
+		if (!ethnl_validate_master_slave_cfg(cfg)) {
+			NL_SET_ERR_MSG_ATTR(info->extack, master_slave_cfg,
+					    "master/slave value is invalid");
+			return -EOPNOTSUPP;
+		}
+	}
+
 	*mod = false;
 	req_speed = tb[ETHTOOL_A_LINKMODES_SPEED];
 	req_duplex = tb[ETHTOOL_A_LINKMODES_DUPLEX];
@@ -311,6 +363,7 @@ static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb,
 			 mod);
 	ethnl_update_u8(&lsettings->duplex, tb[ETHTOOL_A_LINKMODES_DUPLEX],
 			mod);
+	ethnl_update_u8(&lsettings->master_slave_cfg, master_slave_cfg, mod);
 
 	if (!tb[ETHTOOL_A_LINKMODES_OURS] && lsettings->autoneg &&
 	    (req_speed || req_duplex) &&