net: dsa: mv88e6xxx: Add watchdog interrupt handler

The switch contains a watchdog looking for issues with the internal
gubbins of the switch. Hook the interrupt the watchdog triggers and
log the value of the control register indicating why the watchdog
fired. The watchdog can only be cleared with a switch reset, which
will destroy the current configuration. Rather than doing this, just
disable the interrupt.

The mv88e6390 family has different watchdog registers. So use an ops
structure, so support for the mv88e6390 family can be added later.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/global2.c

@@ -649,6 +649,91 @@ int mv88e6xxx_g2_smi_phy_write(struct mv88e6xxx_chip *chip,
 	return mv88e6xxx_g2_smi_phy_write_c22(chip, addr, reg, val, external);
 }
 
+static int mv88e6097_watchdog_action(struct mv88e6xxx_chip *chip, int irq)
+{
+	u16 reg;
+
+	mv88e6xxx_g2_read(chip, GLOBAL2_WDOG_CONTROL, &reg);
+
+	dev_info(chip->dev, "Watchdog event: 0x%04x", reg);
+
+	return IRQ_HANDLED;
+}
+
+static void mv88e6097_watchdog_free(struct mv88e6xxx_chip *chip)
+{
+	u16 reg;
+
+	mv88e6xxx_g2_read(chip, GLOBAL2_WDOG_CONTROL, &reg);
+
+	reg &= ~(GLOBAL2_WDOG_CONTROL_EGRESS_ENABLE |
+		 GLOBAL2_WDOG_CONTROL_QC_ENABLE);
+
+	mv88e6xxx_g2_write(chip, GLOBAL2_WDOG_CONTROL, reg);
+}
+
+static int mv88e6097_watchdog_setup(struct mv88e6xxx_chip *chip)
+{
+	return mv88e6xxx_g2_write(chip, GLOBAL2_WDOG_CONTROL,
+				  GLOBAL2_WDOG_CONTROL_EGRESS_ENABLE |
+				  GLOBAL2_WDOG_CONTROL_QC_ENABLE |
+				  GLOBAL2_WDOG_CONTROL_SWRESET);
+}
+
+const struct mv88e6xxx_irq_ops mv88e6097_watchdog_ops = {
+	.irq_action = mv88e6097_watchdog_action,
+	.irq_setup = mv88e6097_watchdog_setup,
+	.irq_free = mv88e6097_watchdog_free,
+};
+
+static irqreturn_t mv88e6xxx_g2_watchdog_thread_fn(int irq, void *dev_id)
+{
+	struct mv88e6xxx_chip *chip = dev_id;
+	irqreturn_t ret = IRQ_NONE;
+
+	mutex_lock(&chip->reg_lock);
+	if (chip->info->ops->watchdog_ops->irq_action)
+		ret = chip->info->ops->watchdog_ops->irq_action(chip, irq);
+	mutex_unlock(&chip->reg_lock);
+
+	return ret;
+}
+
+static void mv88e6xxx_g2_watchdog_free(struct mv88e6xxx_chip *chip)
+{
+	mutex_lock(&chip->reg_lock);
+	if (chip->info->ops->watchdog_ops->irq_free)
+		chip->info->ops->watchdog_ops->irq_free(chip);
+	mutex_unlock(&chip->reg_lock);
+
+	free_irq(chip->watchdog_irq, chip);
+	irq_dispose_mapping(chip->watchdog_irq);
+}
+
+static int mv88e6xxx_g2_watchdog_setup(struct mv88e6xxx_chip *chip)
+{
+	int err;
+
+	chip->watchdog_irq = irq_find_mapping(chip->g2_irq.domain,
+					      GLOBAL2_INT_SOURCE_WATCHDOG);
+	if (chip->watchdog_irq < 0)
+		return chip->watchdog_irq;
+
+	err = request_threaded_irq(chip->watchdog_irq, NULL,
+				   mv88e6xxx_g2_watchdog_thread_fn,
+				   IRQF_ONESHOT | IRQF_TRIGGER_FALLING,
+				   "mv88e6xxx-watchdog", chip);
+	if (err)
+		return err;
+
+	mutex_lock(&chip->reg_lock);
+	if (chip->info->ops->watchdog_ops->irq_setup)
+		err = chip->info->ops->watchdog_ops->irq_setup(chip);
+	mutex_unlock(&chip->reg_lock);
+
+	return err;
+}
+
 static void mv88e6xxx_g2_irq_mask(struct irq_data *d)
 {
 	struct mv88e6xxx_chip *chip = irq_data_get_irq_chip_data(d);
@@ -737,6 +822,8 @@ void mv88e6xxx_g2_irq_free(struct mv88e6xxx_chip *chip)
 {
 	int irq, virq;
 
+	mv88e6xxx_g2_watchdog_free(chip);
+
 	free_irq(chip->device_irq, chip);
 	irq_dispose_mapping(chip->device_irq);
 
@@ -779,7 +866,7 @@ int mv88e6xxx_g2_irq_setup(struct mv88e6xxx_chip *chip)
 	if (err)
 		goto out;
 
-	return 0;
+	return mv88e6xxx_g2_watchdog_setup(chip);
 
 out:
 	for (irq = 0; irq < 16; irq++) {