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, 9 insertions, 24 deletions

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 966673f44141..fabf01eff771 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -24,7 +24,7 @@
 #include <linux/ftrace.h>
 #include <linux/ioport.h>
 #include <linux/module.h>
-#include <linux/sysdev.h>
+#include <linux/syscore_ops.h>
 #include <linux/delay.h>
 #include <linux/timex.h>
 #include <linux/dmar.h>
@@ -2046,7 +2046,7 @@ static struct {
         unsigned int apic_thmr;
 } apic_pm_state;
 
-static int lapic_suspend(struct sys_device *dev, pm_message_t state)
+static int lapic_suspend(void)
 {
         unsigned long flags;
         int maxlvt;
@@ -2084,23 +2084,21 @@ static int lapic_suspend(struct sys_device *dev, pm_message_t state)
         return 0;
 }
 
-static int lapic_resume(struct sys_device *dev)
+static void lapic_resume(void)
 {
         unsigned int l, h;
         unsigned long flags;
-        int maxlvt;
-        int ret = 0;
+        int maxlvt, ret;
         struct IO_APIC_route_entry **ioapic_entries = NULL;
 
         if (!apic_pm_state.active)
-                return 0;
+                return;
 
         local_irq_save(flags);
         if (intr_remapping_enabled) {
                 ioapic_entries = alloc_ioapic_entries();
                 if (!ioapic_entries) {
                         WARN(1, "Alloc ioapic_entries in lapic resume failed.");
-                        ret = -ENOMEM;
                         goto restore;
                 }
 
@@ -2162,8 +2160,6 @@ static int lapic_resume(struct sys_device *dev)
         }
 restore:
         local_irq_restore(flags);
-
-        return ret;
 }
 
 /*
@@ -2171,17 +2167,11 @@ restore:
  * are needed on every CPU up until machine_halt/restart/poweroff.
  */
 
-static struct sysdev_class lapic_sysclass = {
-        .name           = "lapic",
+static struct syscore_ops lapic_syscore_ops = {
         .resume         = lapic_resume,
         .suspend        = lapic_suspend,
 };
 
-static struct sys_device device_lapic = {
-        .id     = 0,
-        .cls    = &lapic_sysclass,
-};
-
 static void __cpuinit apic_pm_activate(void)
 {
         apic_pm_state.active = 1;
@@ -2189,16 +2179,11 @@ static void __cpuinit apic_pm_activate(void)
 
 static int __init init_lapic_sysfs(void)
 {
-        int error;
-
-        if (!cpu_has_apic)
-                return 0;
         /* XXX: remove suspend/resume procs if !apic_pm_state.active? */
+        if (cpu_has_apic)
+                register_syscore_ops(&lapic_syscore_ops);
 
-        error = sysdev_class_register(&lapic_sysclass);
-        if (!error)
-                error = sysdev_register(&device_lapic);
-        return error;
+        return 0;
 }
 
 /* local apic needs to resume before other devices access its registers. */