net: dsa: mv88e6xx: fix supported_interfaces setup in mv88e6250_phylink_get_caps()

With the recent PHYLINK changes requiring supported_interfaces to be set,
MV88E6250 family switches like the 88E6020 fail to probe - cmode is
never initialized on these devices, so mv88e6250_phylink_get_caps() does
not set any supported_interfaces flags.

Instead of a cmode, on 88E6250 we have a read-only port mode value that
encodes similar information. There is no reason to bother mapping port
mode to the cmodes of other switch models; instead we introduce a
mv88e6250_setup_supported_interfaces() that is called directly from
mv88e6250_phylink_get_caps().

Fixes: de5c9bf4 ("net: phylink: require supported_interfaces to be filled")
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20240417103737.166651-1-matthias.schiffer@ew.tq-group.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -566,13 +566,61 @@ static void mv88e6xxx_translate_cmode(u8 cmode, unsigned long *supported)
 		phy_interface_set_rgmii(supported);
 }
 
-static void mv88e6250_phylink_get_caps(struct mv88e6xxx_chip *chip, int port,
-				       struct phylink_config *config)
+static void
+mv88e6250_setup_supported_interfaces(struct mv88e6xxx_chip *chip, int port,
+				     struct phylink_config *config)
 {
 	unsigned long *supported = config->supported_interfaces;
+	int err;
+	u16 reg;
 
-	/* Translate the default cmode */
-	mv88e6xxx_translate_cmode(chip->ports[port].cmode, supported);
+	err = mv88e6xxx_port_read(chip, port, MV88E6XXX_PORT_STS, &reg);
+	if (err) {
+		dev_err(chip->dev, "p%d: failed to read port status\n", port);
+		return;
+	}
+
+	switch (reg & MV88E6250_PORT_STS_PORTMODE_MASK) {
+	case MV88E6250_PORT_STS_PORTMODE_MII_10_HALF_PHY:
+	case MV88E6250_PORT_STS_PORTMODE_MII_100_HALF_PHY:
+	case MV88E6250_PORT_STS_PORTMODE_MII_10_FULL_PHY:
+	case MV88E6250_PORT_STS_PORTMODE_MII_100_FULL_PHY:
+		__set_bit(PHY_INTERFACE_MODE_REVMII, supported);
+		break;
+
+	case MV88E6250_PORT_STS_PORTMODE_MII_HALF:
+	case MV88E6250_PORT_STS_PORTMODE_MII_FULL:
+		__set_bit(PHY_INTERFACE_MODE_MII, supported);
+		break;
+
+	case MV88E6250_PORT_STS_PORTMODE_MII_DUAL_100_RMII_FULL_PHY:
+	case MV88E6250_PORT_STS_PORTMODE_MII_200_RMII_FULL_PHY:
+	case MV88E6250_PORT_STS_PORTMODE_MII_10_100_RMII_HALF_PHY:
+	case MV88E6250_PORT_STS_PORTMODE_MII_10_100_RMII_FULL_PHY:
+		__set_bit(PHY_INTERFACE_MODE_REVRMII, supported);
+		break;
+
+	case MV88E6250_PORT_STS_PORTMODE_MII_DUAL_100_RMII_FULL:
+	case MV88E6250_PORT_STS_PORTMODE_MII_10_100_RMII_FULL:
+		__set_bit(PHY_INTERFACE_MODE_RMII, supported);
+		break;
+
+	case MV88E6250_PORT_STS_PORTMODE_MII_100_RGMII:
+		__set_bit(PHY_INTERFACE_MODE_RGMII, supported);
+		break;
+
+	default:
+		dev_err(chip->dev,
+			"p%d: invalid port mode in status register: %04x\n",
+			port, reg);
+	}
+}
+
+static void mv88e6250_phylink_get_caps(struct mv88e6xxx_chip *chip, int port,
+				       struct phylink_config *config)
+{
+	if (!mv88e6xxx_phy_is_internal(chip, port))
+		mv88e6250_setup_supported_interfaces(chip, port, config);
 
 	config->mac_capabilities = MAC_SYM_PAUSE | MAC_10 | MAC_100;
 }

drivers/net/dsa/mv88e6xxx/port.h

@@ -25,10 +25,25 @@
 #define MV88E6250_PORT_STS_PORTMODE_PHY_100_HALF	0x0900
 #define MV88E6250_PORT_STS_PORTMODE_PHY_10_FULL		0x0a00
 #define MV88E6250_PORT_STS_PORTMODE_PHY_100_FULL	0x0b00
-#define MV88E6250_PORT_STS_PORTMODE_MII_10_HALF		0x0c00
-#define MV88E6250_PORT_STS_PORTMODE_MII_100_HALF	0x0d00
-#define MV88E6250_PORT_STS_PORTMODE_MII_10_FULL		0x0e00
-#define MV88E6250_PORT_STS_PORTMODE_MII_100_FULL	0x0f00
+/* - Modes with PHY suffix use output instead of input clock
+ * - Modes without RMII or RGMII use MII
+ * - Modes without speed do not have a fixed speed specified in the manual
+ *   ("DC to x MHz" - variable clock support?)
+ */
+#define MV88E6250_PORT_STS_PORTMODE_MII_DISABLED		0x0000
+#define MV88E6250_PORT_STS_PORTMODE_MII_100_RGMII		0x0100
+#define MV88E6250_PORT_STS_PORTMODE_MII_DUAL_100_RMII_FULL_PHY	0x0200
+#define MV88E6250_PORT_STS_PORTMODE_MII_200_RMII_FULL_PHY	0x0400
+#define MV88E6250_PORT_STS_PORTMODE_MII_DUAL_100_RMII_FULL	0x0600
+#define MV88E6250_PORT_STS_PORTMODE_MII_10_100_RMII_FULL	0x0700
+#define MV88E6250_PORT_STS_PORTMODE_MII_HALF			0x0800
+#define MV88E6250_PORT_STS_PORTMODE_MII_10_100_RMII_HALF_PHY	0x0900
+#define MV88E6250_PORT_STS_PORTMODE_MII_FULL			0x0a00
+#define MV88E6250_PORT_STS_PORTMODE_MII_10_100_RMII_FULL_PHY	0x0b00
+#define MV88E6250_PORT_STS_PORTMODE_MII_10_HALF_PHY		0x0c00
+#define MV88E6250_PORT_STS_PORTMODE_MII_100_HALF_PHY		0x0d00
+#define MV88E6250_PORT_STS_PORTMODE_MII_10_FULL_PHY		0x0e00
+#define MV88E6250_PORT_STS_PORTMODE_MII_100_FULL_PHY		0x0f00
 #define MV88E6XXX_PORT_STS_LINK			0x0800
 #define MV88E6XXX_PORT_STS_DUPLEX		0x0400
 #define MV88E6XXX_PORT_STS_SPEED_MASK		0x0300