x86: Use syscore_ops instead of sysdev classes and sysdevs

Some subsystems in the x86 tree need to carry out suspend/resume and
shutdown operations with one CPU on-line and interrupts disabled and
they define sysdev classes and sysdevs or sysdev drivers for this
purpose.  This leads to unnecessarily complicated code and excessive
memory usage, so switch them to using struct syscore_ops objects for
this purpose instead.

Generally, there are three categories of subsystems that use
sysdevs for implementing PM operations: (1) subsystems whose
suspend/resume callbacks ignore their arguments entirely (the
majority), (2) subsystems whose suspend/resume callbacks use their
struct sys_device argument, but don't really need to do that,
because they can be implemented differently in an arguably simpler
way (io_apic.c), and (3) subsystems whose suspend/resume callbacks
use their struct sys_device argument, but the value of that argument
is always the same and could be ignored (microcode_core.c).  In all
of these cases the subsystems in question may be readily converted to
using struct syscore_ops objects for power management and shutdown.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 23 deletions

diff --git a/arch/x86/kernel/i8237.c b/arch/x86/kernel/i8237.c
index b42ca694dc6..8eeaa81de06 100644
--- a/arch/x86/kernel/i8237.c
+++ b/arch/x86/kernel/i8237.c
@@ -10,7 +10,7 @@
  */
 
 #include <linux/init.h>
-#include <linux/sysdev.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/dma.h>
 
@@ -21,7 +21,7 @@
  * in asm/dma.h.
  */
 
-static int i8237A_resume(struct sys_device *dev)
+static void i8237A_resume(void)
 {
 	unsigned long flags;
 	int i;
@@ -41,31 +41,15 @@ static int i8237A_resume(struct sys_device *dev)
 	enable_dma(4);
 
 	release_dma_lock(flags);
-
-	return 0;
 }
 
-static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
-{
-	return 0;
-}
-
-static struct sysdev_class i8237_sysdev_class = {
-	.name		= "i8237",
-	.suspend	= i8237A_suspend,
+static struct syscore_ops i8237_syscore_ops = {
 	.resume		= i8237A_resume,
 };
 
-static struct sys_device device_i8237A = {
-	.id		= 0,
-	.cls		= &i8237_sysdev_class,
-};
-
-static int __init i8237A_init_sysfs(void)
+static int __init i8237A_init_ops(void)
 {
-	int error = sysdev_class_register(&i8237_sysdev_class);
-	if (!error)
-		error = sysdev_register(&device_i8237A);
-	return error;
+	register_syscore_ops(&i8237_syscore_ops);
+	return 0;
 }
-device_initcall(i8237A_init_sysfs);
+device_initcall(i8237A_init_ops);