net: dsa: mv88e6xxx: Wait for EEPROM done after HW reset

When the switch is hardware reset, it reads the contents of the
EEPROM. This can contain instructions for programming values into
registers and to perform waits between such programming. Reading the
EEPROM can take longer than the 100ms mv88e6xxx_hardware_reset() waits
after deasserting the reset GPIO. So poll the EEPROM done bit to
ensure it is complete.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Ruslan Sushko <rus@sushko.dev>
Link: https://lore.kernel.org/r/20201116164301.977661-1-rus@sushko.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: lunn

drivers/net/dsa/mv88e6xxx/chip.c

@@ -2297,6 +2297,8 @@ static void mv88e6xxx_hardware_reset(struct mv88e6xxx_chip *chip)
 		usleep_range(10000, 20000);
 		gpiod_set_value_cansleep(gpiod, 0);
 		usleep_range(10000, 20000);
+
+		mv88e6xxx_g1_wait_eeprom_done(chip);
 	}
 }
 

drivers/net/dsa/mv88e6xxx/global1.c

@@ -75,6 +75,37 @@ static int mv88e6xxx_g1_wait_init_ready(struct mv88e6xxx_chip *chip)
 	return mv88e6xxx_g1_wait_bit(chip, MV88E6XXX_G1_STS, bit, 1);
 }
 
+void mv88e6xxx_g1_wait_eeprom_done(struct mv88e6xxx_chip *chip)
+{
+	const unsigned long timeout = jiffies + 1 * HZ;
+	u16 val;
+	int err;
+
+	/* Wait up to 1 second for the switch to finish reading the
+	 * EEPROM.
+	 */
+	while (time_before(jiffies, timeout)) {
+		err = mv88e6xxx_g1_read(chip, MV88E6XXX_G1_STS, &val);
+		if (err) {
+			dev_err(chip->dev, "Error reading status");
+			return;
+		}
+
+		/* If the switch is still resetting, it may not
+		 * respond on the bus, and so MDIO read returns
+		 * 0xffff. Differentiate between that, and waiting for
+		 * the EEPROM to be done by bit 0 being set.
+		 */
+		if (val != 0xffff &&
+		    val & BIT(MV88E6XXX_G1_STS_IRQ_EEPROM_DONE))
+			return;
+
+		usleep_range(1000, 2000);
+	}
+
+	dev_err(chip->dev, "Timeout waiting for EEPROM done");
+}
+
 /* Offset 0x01: Switch MAC Address Register Bytes 0 & 1
  * Offset 0x02: Switch MAC Address Register Bytes 2 & 3
  * Offset 0x03: Switch MAC Address Register Bytes 4 & 5

drivers/net/dsa/mv88e6xxx/global1.h

@@ -278,6 +278,7 @@ int mv88e6xxx_g1_set_switch_mac(struct mv88e6xxx_chip *chip, u8 *addr);
 int mv88e6185_g1_reset(struct mv88e6xxx_chip *chip);
 int mv88e6352_g1_reset(struct mv88e6xxx_chip *chip);
 int mv88e6250_g1_reset(struct mv88e6xxx_chip *chip);
+void mv88e6xxx_g1_wait_eeprom_done(struct mv88e6xxx_chip *chip);
 
 int mv88e6185_g1_ppu_enable(struct mv88e6xxx_chip *chip);
 int mv88e6185_g1_ppu_disable(struct mv88e6xxx_chip *chip);