IRQ resource deallocation [1/2]

diff -puN drivers/acpi/pci_irq.c~IRQ_deallocation_acpi drivers/acpi/pci_irq.c
@@ -407,3 +407,55 @@ acpi_pci_irq_enable (
 }
 EXPORT_SYMBOL(acpi_pci_irq_enable);
 
+
+#ifdef CONFIG_ACPI_DEALLOCATE_IRQ
+void
+acpi_pci_irq_disable (
+	struct pci_dev		*dev)
+{
+	u32			gsi = 0;
+	u8			pin = 0;
+	int			edge_level = ACPI_LEVEL_SENSITIVE;
+	int			active_high_low = ACPI_ACTIVE_LOW;
+
+	ACPI_FUNCTION_TRACE("acpi_pci_irq_disable");
+
+	if (!dev)
+		return_VOID;
+	
+	pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
+	if (!pin)
+		return_VOID;
+	pin--;
+
+	if (!dev->bus)
+		return_VOID;
+
+	/* 
+	 * First we check the PCI IRQ routing table (PRT) for an IRQ.
+	 */
+ 	gsi = acpi_pci_irq_lookup(dev->bus, PCI_SLOT(dev->devfn), pin,
+				  &edge_level, &active_high_low);
+	/*
+	 * If no PRT entry was found, we'll try to derive an IRQ from the
+	 * device's parent bridge.
+	 */
+	if (!gsi)
+ 		gsi = acpi_pci_irq_derive(dev, pin,
+					  &edge_level, &active_high_low);
+	if (!gsi)
+		return_VOID;
+
+	/*
+	 * TBD: It might be worth clearing dev->irq by magic constant
+	 * (e.g. PCI_UNDEFINED_IRQ).
+	 */
+
+	printk(KERN_INFO PREFIX "PCI interrupt for device %s disabled\n",
+	       pci_name(dev));
+
+	acpi_unregister_gsi(gsi);
+
+	return_VOID;
+}
+#endif /* CONFIG_ACPI_DEALLOCATE_IRQ */

diff -puN include/linux/acpi.h~IRQ_deallocation_acpi include/linux/acpi.h
@@ -416,6 +416,15 @@ static inline int acpi_boot_init(void)
 unsigned int acpi_register_gsi (u32 gsi, int edge_level, int active_high_low);
 int acpi_gsi_to_irq (u32 gsi, unsigned int *irq);
 
+/*
+ * This function undoes the effect of one call to acpi_register_gsi().
+ * If this matches the last registration, any IRQ resources for gsi
+ * are freed.
+ */
+#ifdef CONFIG_ACPI_DEALLOCATE_IRQ
+void acpi_unregister_gsi (u32 gsi);
+#endif
+
 #ifdef CONFIG_ACPI_PCI
 
 struct acpi_prt_entry {

@@ -441,6 +450,10 @@ struct pci_dev;
 int acpi_pci_irq_enable (struct pci_dev *dev);
 void acpi_penalize_isa_irq(int irq);
 
+#ifdef CONFIG_ACPI_DEALLOCATE_IRQ
+void acpi_pci_irq_disable (struct pci_dev *dev);
+#endif
+
 struct acpi_pci_driver {
 	struct acpi_pci_driver *next;
 	int (*add)(acpi_handle handle);