net: sfp: add support for HALNy GPON SFP

Add a quirk for the HALNy HL-GSFP module, which appears to have an
inverted RX_LOS signal, and maybe uses TX_FAULT as a serial port
transmit pin. Rather than use these hardware signals, switch to
using software polling for these status signals.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/sfp-bus.c

@@ -283,7 +283,7 @@ void sfp_parse_support(struct sfp_bus *bus, const struct sfp_eeprom_id *id,
 			phylink_set(modes, 2500baseX_Full);
 	}
 
-	if (bus->sfp_quirk)
+	if (bus->sfp_quirk && bus->sfp_quirk->modes)
 		bus->sfp_quirk->modes(id, modes);
 
 	linkmode_or(support, support, modes);

drivers/net/phy/sfp.c

@@ -321,6 +321,15 @@ static void sfp_fixup_ignore_tx_fault(struct sfp *sfp)
 	sfp->tx_fault_ignore = true;
 }
 
+static void sfp_fixup_halny_gsfp(struct sfp *sfp)
+{
+	/* Ignore the TX_FAULT and LOS signals on this module.
+	 * these are possibly used for other purposes on this
+	 * module, e.g. a serial port.
+	 */
+	sfp->state_hw_mask &= ~(SFP_F_TX_FAULT | SFP_F_LOS);
+}
+
 static void sfp_quirk_2500basex(const struct sfp_eeprom_id *id,
 				unsigned long *modes)
 {
@@ -352,6 +361,10 @@ static const struct sfp_quirk sfp_quirks[] = {
 		.part = "3FE46541AA",
 		.modes = sfp_quirk_2500basex,
 		.fixup = sfp_fixup_long_startup,
+	}, {
+		.vendor = "HALNy",
+		.part = "HL-GSFP",
+		.fixup = sfp_fixup_halny_gsfp,
 	}, {
 		// Huawei MA5671A can operate at 2500base-X, but report 1.2GBd
 		// NRZ in their EEPROM
@@ -369,16 +382,18 @@ static const struct sfp_quirk sfp_quirks[] = {
 		.vendor = "UBNT",
 		.part = "UF-INSTANT",
 		.modes = sfp_quirk_ubnt_uf_instant,
-	},
+	}
 };
 
 static size_t sfp_strlen(const char *str, size_t maxlen)
 {
 	size_t size, i;
 
-	/* Trailing characters should be filled with space chars */
+	/* Trailing characters should be filled with space chars, but
+	 * some manufacturers can't read SFF-8472 and use NUL.
+	 */
 	for (i = 0, size = 0; i < maxlen; i++)
-		if (str[i] != ' ')
+		if (str[i] != ' ' && str[i] != '\0')
 			size = i + 1;
 
 	return size;