ACPI: Use syscore_ops instead of sysdev class and sysdev

ACPI uses a sysdev class and a sysdev for executing
irqrouter_resume() before turning on interrupts on the boot CPU.
However, since irqrouter_resume() ignores its argument, the entire
mechanism may be replaced with a struct syscore_ops object which
is considerably simpler.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>

drivers/acpi/pci_link.c

···
  *	   for IRQ management (e.g. start()->_SRS).
  */
 
-#include <linux/sysdev.h>
+#include <linux/syscore_ops.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
···
 	return 0;
 }
 
-static int irqrouter_resume(struct sys_device *dev)
+static void irqrouter_resume(void)
 {
 	struct acpi_pci_link *link;
 
 	list_for_each_entry(link, &acpi_link_list, list) {
 		acpi_pci_link_resume(link);
 	}
-	return 0;
 }
 
 static int acpi_pci_link_remove(struct acpi_device *device, int type)
···
 
 __setup("acpi_irq_balance", acpi_irq_balance_set);
 
-/* FIXME: we will remove this interface after all drivers call pci_disable_device */
-static struct sysdev_class irqrouter_sysdev_class = {
-	.name = "irqrouter",
+static struct syscore_ops irqrouter_syscore_ops = {
 	.resume = irqrouter_resume,
 };
 
-static struct sys_device device_irqrouter = {
-	.id = 0,
-	.cls = &irqrouter_sysdev_class,
-};
-
-static int __init irqrouter_init_sysfs(void)
+static int __init irqrouter_init_ops(void)
 {
-	int error;
+	if (!acpi_disabled && !acpi_noirq)
+		register_syscore_ops(&irqrouter_syscore_ops);
 
-	if (acpi_disabled || acpi_noirq)
-		return 0;
-
-	error = sysdev_class_register(&irqrouter_sysdev_class);
-	if (!error)
-		error = sysdev_register(&device_irqrouter);
-
-	return error;
+	return 0;
 }
 
-device_initcall(irqrouter_init_sysfs);
+device_initcall(irqrouter_init_ops);
 
 static int __init acpi_pci_link_init(void)
 {