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>

3 files changed, 19 insertions, 1 deletions

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 92f737f10117..f4662b3a9e1e 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -1666,6 +1666,18 @@ static inline int ethtool_validate_duplex(__u8 duplex)
 	return 0;
 }
 
+#define MASTER_SLAVE_CFG_UNSUPPORTED		0
+#define MASTER_SLAVE_CFG_UNKNOWN		1
+#define MASTER_SLAVE_CFG_MASTER_PREFERRED	2
+#define MASTER_SLAVE_CFG_SLAVE_PREFERRED	3
+#define MASTER_SLAVE_CFG_MASTER_FORCE		4
+#define MASTER_SLAVE_CFG_SLAVE_FORCE		5
+#define MASTER_SLAVE_STATE_UNSUPPORTED		0
+#define MASTER_SLAVE_STATE_UNKNOWN		1
+#define MASTER_SLAVE_STATE_MASTER		2
+#define MASTER_SLAVE_STATE_SLAVE		3
+#define MASTER_SLAVE_STATE_ERR			4
+
 /* Which connector port. */
 #define PORT_TP			0x00
 #define PORT_AUI		0x01
@@ -1904,7 +1916,9 @@ struct ethtool_link_settings {
 	__u8	eth_tp_mdix_ctrl;
 	__s8	link_mode_masks_nwords;
 	__u8	transceiver;
-	__u8	reserved1[3];
+	__u8	master_slave_cfg;
+	__u8	master_slave_state;
+	__u8	reserved1[1];
 	__u32	reserved[7];
 	__u32	link_mode_masks[0];
 	/* layout of link_mode_masks fields:
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 7fde76366ba4..bf1d310e20bc 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -216,6 +216,8 @@ enum {
 	ETHTOOL_A_LINKMODES_PEER,		/* bitset */
 	ETHTOOL_A_LINKMODES_SPEED,		/* u32 */
 	ETHTOOL_A_LINKMODES_DUPLEX,		/* u8 */
+	ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG,	/* u8 */
+	ETHTOOL_A_LINKMODES_MASTER_SLAVE_STATE,	/* u8 */
 
 	/* add new constants above here */
 	__ETHTOOL_A_LINKMODES_CNT,
diff --git a/include/uapi/linux/mii.h b/include/uapi/linux/mii.h
index 90f9b4e1ba27..39f7c44baf53 100644
--- a/include/uapi/linux/mii.h
+++ b/include/uapi/linux/mii.h
@@ -151,11 +151,13 @@
 /* 1000BASE-T Control register */
 #define ADVERTISE_1000FULL	0x0200  /* Advertise 1000BASE-T full duplex */
 #define ADVERTISE_1000HALF	0x0100  /* Advertise 1000BASE-T half duplex */
+#define CTL1000_PREFER_MASTER	0x0400  /* prefer to operate as master */
 #define CTL1000_AS_MASTER	0x0800
 #define CTL1000_ENABLE_MASTER	0x1000
 
 /* 1000BASE-T Status register */
 #define LPA_1000MSFAIL		0x8000	/* Master/Slave resolution failure */
+#define LPA_1000MSRES		0x4000	/* Master/Slave resolution status */
 #define LPA_1000LOCALRXOK	0x2000	/* Link partner local receiver status */
 #define LPA_1000REMRXOK		0x1000	/* Link partner remote receiver status */
 #define LPA_1000FULL		0x0800	/* Link partner 1000BASE-T full duplex */