genirq: Add irq_chip_(startup/shutdown)_parent()

As the MSI controller on SG2044 uses PLIC as the underlying interrupt
controller, it needs to call irq_enable() and irq_disable() to
startup/shutdown interrupts. Otherwise, the MSI interrupt can not be
startup correctly and will not respond any incoming interrupt.

Introduce irq_chip_startup_parent() and irq_chip_shutdown_parent() to allow
the interrupt controller to call the irq_startup()/irq_shutdown() callbacks
of the parent interrupt chip.

In case the irq_startup()/irq_shutdown() callbacks are not implemented for
the parent interrupt chip, this will fallback to irq_chip_enable_parent()
or irq_chip_disable_parent().

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Chen Wang <unicorn_wang@outlook.com> # Pioneerbox
Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
Link: https://lore.kernel.org/all/20250813232835.43458-2-inochiama@gmail.com
Link: https://lore.kernel.org/lkml/20250722224513.22125-1-inochiama@gmail.com/

Author: inochisa

include/linux/irq.h

@@ -669,6 +669,8 @@ extern int irq_chip_set_parent_state(struct irq_data *data,
 extern int irq_chip_get_parent_state(struct irq_data *data,
 				     enum irqchip_irq_state which,
 				     bool *state);
+extern void irq_chip_shutdown_parent(struct irq_data *data);
+extern unsigned int irq_chip_startup_parent(struct irq_data *data);
 extern void irq_chip_enable_parent(struct irq_data *data);
 extern void irq_chip_disable_parent(struct irq_data *data);
 extern void irq_chip_ack_parent(struct irq_data *data);

kernel/irq/chip.c

@@ -1259,6 +1259,43 @@ int irq_chip_get_parent_state(struct irq_data *data,
 }
 EXPORT_SYMBOL_GPL(irq_chip_get_parent_state);
 
+/**
+ * irq_chip_shutdown_parent - Shutdown the parent interrupt
+ * @data:	Pointer to interrupt specific data
+ *
+ * Invokes the irq_shutdown() callback of the parent if available or falls
+ * back to irq_chip_disable_parent().
+ */
+void irq_chip_shutdown_parent(struct irq_data *data)
+{
+	struct irq_data *parent = data->parent_data;
+
+	if (parent->chip->irq_shutdown)
+		parent->chip->irq_shutdown(parent);
+	else
+		irq_chip_disable_parent(data);
+}
+EXPORT_SYMBOL_GPL(irq_chip_shutdown_parent);
+
+/**
+ * irq_chip_startup_parent - Startup the parent interrupt
+ * @data:	Pointer to interrupt specific data
+ *
+ * Invokes the irq_startup() callback of the parent if available or falls
+ * back to irq_chip_enable_parent().
+ */
+unsigned int irq_chip_startup_parent(struct irq_data *data)
+{
+	struct irq_data *parent = data->parent_data;
+
+	if (parent->chip->irq_startup)
+		return parent->chip->irq_startup(parent);
+
+	irq_chip_enable_parent(data);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_chip_startup_parent);
+
 /**
  * irq_chip_enable_parent - Enable the parent interrupt (defaults to unmask if
  * NULL)