Merge branch 'net-phy-bcm54811-phy-initialization'

 says:

====================
net: phy: bcm54811: PHY initialization

Proper bcm54811 PHY driver initialization for MII-Lite.

The bcm54811 PHY in MLP package must be setup for MII-Lite interface
mode by software. Normally, the PHY to MAC interface is selected in
hardware by setting the bootstrap pins of the PHY. However, MII and
MII-Lite share the same hardware setup and must be distinguished by
software, setting appropriate bit in a configuration register.
The MII-Lite interface mode is non-standard one, defined by Broadcom
for some of their PHYs. The MII-Lite lightness consist in omitting
RXER, TXER, CRS and COL signals of the standard MII interface.
Absence of COL them makes half-duplex links modes impossible but
does not interfere with Broadcom's BroadR-Reach link modes, because
they are full-duplex only.
To do it in a clean way, MII-Lite must be introduced first, including
its limitation to link modes (no half-duplex), because it is a
prerequisite for the patch #3 of this series. The patch #4 does not
depend on MII-Lite directly but both #3 and #4 are necessary for
bcm54811 to work properly without additional configuration steps to be
done - for example in the bootloader, before the kernel starts.

PATCH 1 - Add MII-Lite PHY interface mode as defined by Broadcom for
   their two-wire PHYs. It can be used with most Ethernet controllers
   under certain limitations (no half-duplex link modes etc.).

PATCH 2 - Add MII-Lite PHY interface type

PATCH 3 - Activation of MII-Lite interface mode on Broadcom bcm5481x
   PHYs

PATCH 4 - Initialize the BCM54811 PHY properly so that it conforms
   to the datasheet regarding a reserved bit in the LRE Control
   register, which must be written to zero after every device reset.
   Ignore the LDS capability bit in LRE Status register on bcm54811.
====================

Link: https://patch.msgid.link/20250708090140.61355-1-kamilh@axis.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

8 files changed, 58 insertions, 5 deletions

diff --git a/Documentation/devicetree/bindings/net/ethernet-controller.yaml b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
index 7cbf11bbe99c..66b1cfbbfe22 100644
--- a/Documentation/devicetree/bindings/net/ethernet-controller.yaml
+++ b/Documentation/devicetree/bindings/net/ethernet-controller.yaml
@@ -39,6 +39,7 @@ properties:
       # MAC.
       - internal
       - mii
+      - mii-lite
       - gmii
       - sgmii
       - psgmii
diff --git a/Documentation/networking/phy.rst b/Documentation/networking/phy.rst
index f64641417c54..7f159043ad5a 100644
--- a/Documentation/networking/phy.rst
+++ b/Documentation/networking/phy.rst
@@ -333,6 +333,13 @@ Some of the interface modes are described below:
     SerDes lane, each port having speeds of 2.5G / 1G / 100M / 10M achieved
     through symbol replication. The PCS expects the standard USXGMII code word.
 
+``PHY_INTERFACE_MODE_MIILITE``
+    Non-standard, simplified MII mode, without TXER, RXER, CRS and COL signals
+    as defined for the MII. The absence of COL signal makes half-duplex link
+    modes impossible but does not interfere with BroadR-Reach link modes on
+    Broadcom (and other two-wire Ethernet) PHYs, because they are full-duplex
+    only.
+
 Pause frames / flow control
 ===========================
 
diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
index 9b1de54fd483..a60e58ef90c4 100644
--- a/drivers/net/phy/broadcom.c
+++ b/drivers/net/phy/broadcom.c
@@ -407,7 +407,7 @@ static int bcm5481x_set_brrmode(struct phy_device *phydev, bool on)
 static int bcm54811_config_init(struct phy_device *phydev)
 {
 	struct bcm54xx_phy_priv *priv = phydev->priv;
-	int err, reg;
+	int err, reg, exp_sync_ethernet;
 
 	/* Enable CLK125 MUX on LED4 if ref clock is enabled. */
 	if (!(phydev->dev_flags & PHY_BRCM_RX_REFCLK_UNUSED)) {
@@ -424,6 +424,18 @@ static int bcm54811_config_init(struct phy_device *phydev)
 	if (priv->brr_mode)
 		phydev->autoneg = 0;
 
+	/* Enable MII Lite (No TXER, RXER, CRS, COL) if configured */
+	if (phydev->interface == PHY_INTERFACE_MODE_MIILITE)
+		exp_sync_ethernet = BCM_EXP_SYNC_ETHERNET_MII_LITE;
+	else
+		exp_sync_ethernet = 0;
+
+	err = bcm_phy_modify_exp(phydev, BCM_EXP_SYNC_ETHERNET,
+				 BCM_EXP_SYNC_ETHERNET_MII_LITE,
+				 exp_sync_ethernet);
+	if (err < 0)
+		return err;
+
 	return bcm5481x_set_brrmode(phydev, priv->brr_mode);
 }
 
@@ -655,7 +667,7 @@ static int bcm5481x_read_abilities(struct phy_device *phydev)
 {
 	struct device_node *np = phydev->mdio.dev.of_node;
 	struct bcm54xx_phy_priv *priv = phydev->priv;
-	int i, val, err;
+	int i, val, err, aneg;
 
 	for (i = 0; i < ARRAY_SIZE(bcm54811_linkmodes); i++)
 		linkmode_clear_bit(bcm54811_linkmodes[i], phydev->supported);
@@ -676,9 +688,19 @@ static int bcm5481x_read_abilities(struct phy_device *phydev)
 		if (val < 0)
 			return val;
 
+		/* BCM54811 is not capable of LDS but the corresponding bit
+		 * in LRESR is set to 1 and marked "Ignore" in the datasheet.
+		 * So we must read the bcm54811 as unable to auto-negotiate
+		 * in BroadR-Reach mode.
+		 */
+		if (BRCM_PHY_MODEL(phydev) == PHY_ID_BCM54811)
+			aneg = 0;
+		else
+			aneg = val & LRESR_LDSABILITY;
+
 		linkmode_mod_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
 				 phydev->supported,
-				 val & LRESR_LDSABILITY);
+				 aneg);
 		linkmode_mod_bit(ETHTOOL_LINK_MODE_100baseT1_Full_BIT,
 				 phydev->supported,
 				 val & LRESR_100_1PAIR);
@@ -735,8 +757,15 @@ static int bcm54811_config_aneg(struct phy_device *phydev)
 
 	/* Aneg firstly. */
 	if (priv->brr_mode) {
-		/* BCM54811 is only capable of autonegotiation in IEEE mode */
-		phydev->autoneg = 0;
+		/* BCM54811 is only capable of autonegotiation in IEEE mode.
+		 * In BroadR-Reach mode, disable the Long Distance Signaling,
+		 * the BRR mode autoneg as supported in other Broadcom PHYs.
+		 * This bit is marked as "Reserved" and "Default 1, must be
+		 *  written to 0 after every device reset" in the datasheet.
+		 */
+		ret = phy_modify(phydev, MII_BCM54XX_LRECR, LRECR_LDSEN, 0);
+		if (ret < 0)
+			return ret;
 		ret = bcm_config_lre_aneg(phydev, false);
 	} else {
 		ret = genphy_config_aneg(phydev);
diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
index c480bb40fa73..605ca20ae192 100644
--- a/drivers/net/phy/phy-core.c
+++ b/drivers/net/phy/phy-core.c
@@ -115,6 +115,7 @@ int phy_interface_num_ports(phy_interface_t interface)
 		return 0;
 	case PHY_INTERFACE_MODE_INTERNAL:
 	case PHY_INTERFACE_MODE_MII:
+	case PHY_INTERFACE_MODE_MIILITE:
 	case PHY_INTERFACE_MODE_GMII:
 	case PHY_INTERFACE_MODE_TBI:
 	case PHY_INTERFACE_MODE_REVMII:
diff --git a/drivers/net/phy/phy_caps.c b/drivers/net/phy/phy_caps.c
index d11ce1c7e712..2cc9ee97e867 100644
--- a/drivers/net/phy/phy_caps.c
+++ b/drivers/net/phy/phy_caps.c
@@ -316,6 +316,10 @@ unsigned long phy_caps_from_interface(phy_interface_t interface)
 		link_caps |= BIT(LINK_CAPA_100HD) | BIT(LINK_CAPA_100FD);
 		break;
 
+	case PHY_INTERFACE_MODE_MIILITE:
+		link_caps |= BIT(LINK_CAPA_10FD) | BIT(LINK_CAPA_100FD);
+		break;
+
 	case PHY_INTERFACE_MODE_TBI:
 	case PHY_INTERFACE_MODE_MOCA:
 	case PHY_INTERFACE_MODE_RTBI:
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index f5473510b762..c7f867b361dd 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -237,6 +237,7 @@ static int phylink_interface_max_speed(phy_interface_t interface)
 	case PHY_INTERFACE_MODE_SMII:
 	case PHY_INTERFACE_MODE_REVMII:
 	case PHY_INTERFACE_MODE_MII:
+	case PHY_INTERFACE_MODE_MIILITE:
 		return SPEED_100;
 
 	case PHY_INTERFACE_MODE_TBI:
diff --git a/include/linux/brcmphy.h b/include/linux/brcmphy.h
index 028b3e00378e..15c35655f482 100644
--- a/include/linux/brcmphy.h
+++ b/include/linux/brcmphy.h
@@ -183,6 +183,12 @@
 #define BCM_LED_MULTICOLOR_PROGRAM	0xa
 
 /*
+ * Broadcom Synchronous Ethernet Controls (expansion register 0x0E)
+ */
+#define BCM_EXP_SYNC_ETHERNET		(MII_BCM54XX_EXP_SEL_ER + 0x0E)
+#define BCM_EXP_SYNC_ETHERNET_MII_LITE	BIT(11)
+
+/*
  * BCM5482: Shadow registers
  * Shadow values go into bits [14:10] of register 0x1c to select a shadow
  * register to access.
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 543a94751a6b..4c2b8b6e7187 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -106,6 +106,7 @@ extern const int phy_basic_ports_array[3];
  * @PHY_INTERFACE_MODE_50GBASER: 50GBase-R - with Clause 134 FEC
  * @PHY_INTERFACE_MODE_LAUI: 50 Gigabit Attachment Unit Interface
  * @PHY_INTERFACE_MODE_100GBASEP: 100GBase-P - with Clause 134 FEC
+ * @PHY_INTERFACE_MODE_MIILITE: MII-Lite - MII without RXER TXER CRS COL
  * @PHY_INTERFACE_MODE_MAX: Book keeping
  *
  * Describes the interface between the MAC and PHY.
@@ -150,6 +151,7 @@ typedef enum {
 	PHY_INTERFACE_MODE_50GBASER,
 	PHY_INTERFACE_MODE_LAUI,
 	PHY_INTERFACE_MODE_100GBASEP,
+	PHY_INTERFACE_MODE_MIILITE,
 	PHY_INTERFACE_MODE_MAX,
 } phy_interface_t;
 
@@ -272,6 +274,8 @@ static inline const char *phy_modes(phy_interface_t interface)
 		return "laui";
 	case PHY_INTERFACE_MODE_100GBASEP:
 		return "100gbase-p";
+	case PHY_INTERFACE_MODE_MIILITE:
+		return "mii-lite";
 	default:
 		return "unknown";
 	}