Add generic cpu_idle support

sparc32:
- replace call to cpu_idle() with cpu_startup_entry()
- add arch_cpu_idle()

sparc64:
- smp_callin() includes cpu_startup_entry() call so we can
  skip calling cpu_idle from assembler
- add arch_cpu_idle_enter() and arch_cpu_idle_dead()

Signed-off-by: Sam Ravnborg <s...@ravnborg.org>
Cc: David S. Miller <da...@davemloft.net>

---
This patch is on top of smp/testing in the tip tree.
It is build tested on sparc32 + sparc64

        Sam


diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 3d361f2..5f22169 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -39,6 +39,7 @@ config SPARC
        select GENERIC_CLOCKEVENTS
        select GENERIC_STRNCPY_FROM_USER
        select GENERIC_STRNLEN_USER
+       select GENERIC_IDLE_LOOP
        select MODULES_USE_ELF_RELA
        select ODD_RT_SIGACTION
        select OLD_SIGSUSPEND
diff --git a/arch/sparc/kernel/hvtramp.S b/arch/sparc/kernel/hvtramp.S
index 9365432..605c960 100644
--- a/arch/sparc/kernel/hvtramp.S
+++ b/arch/sparc/kernel/hvtramp.S
@@ -128,8 +128,7 @@ hv_cpu_startup:
 
        call            smp_callin
         nop
-       call            cpu_idle
-        mov            0, %o0
+
        call            cpu_panic
         nop
 
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 62eede1..ec92959 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -64,23 +64,13 @@ extern void fpsave(unsigned long *, unsigned long *, void 
*, unsigned long *);
 struct task_struct *last_task_used_math = NULL;
 struct thread_info *current_set[NR_CPUS];
 
-/*
- * the idle loop on a Sparc... ;)
- */
-void cpu_idle(void)
+/* the idle loop on a Sparc... ;) */
+void arch_cpu_idle(void)
 {
-       set_thread_flag(TIF_POLLING_NRFLAG);
-
-       /* endless idle loop with no priority at all */
-       for (;;) {
-               while (!need_resched()) {
-                       if (sparc_idle)
-                               (*sparc_idle)();
-                       else
-                               cpu_relax();
-               }
-               schedule_preempt_disabled();
-       }
+       if (sparc_idle)
+               (*sparc_idle)();
+       else
+               cpu_relax();
 }
 
 /* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index cdb80b2..5ed6b02 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -52,8 +52,13 @@
 
 #include "kstack.h"
 
-static void sparc64_yield(int cpu)
+/* The idle loop on sparc64. */
+void arch_cpu_idle_enter()
 {
+       int cpu;
+
+       cpu = smp_processor_id();
+
        if (tlb_type != hypervisor) {
                touch_nmi_watchdog();
                return;
@@ -88,31 +93,10 @@ static void sparc64_yield(int cpu)
        set_thread_flag(TIF_POLLING_NRFLAG);
 }
 
-/* The idle loop on sparc64. */
-void cpu_idle(void)
+void arch_cpu_idle_dead()
 {
-       int cpu = smp_processor_id();
-
-       set_thread_flag(TIF_POLLING_NRFLAG);
-
-       while(1) {
-               tick_nohz_idle_enter();
-               rcu_idle_enter();
-
-               while (!need_resched() && !cpu_is_offline(cpu))
-                       sparc64_yield(cpu);
-
-               rcu_idle_exit();
-               tick_nohz_idle_exit();
-
-#ifdef CONFIG_HOTPLUG_CPU
-               if (cpu_is_offline(cpu)) {
-                       sched_preempt_enable_no_resched();
-                       cpu_play_dead();
-               }
-#endif
-               schedule_preempt_disabled();
-       }
+       sched_preempt_enable_no_resched();
+       cpu_play_dead();
 }
 
 #ifdef CONFIG_COMPAT
diff --git a/arch/sparc/kernel/smp_32.c b/arch/sparc/kernel/smp_32.c
index 9e7e6d7..e3f2b81 100644
--- a/arch/sparc/kernel/smp_32.c
+++ b/arch/sparc/kernel/smp_32.c
@@ -369,7 +369,7 @@ void __cpuinit sparc_start_secondary(void *arg)
        local_irq_enable();
 
        wmb();
-       cpu_idle();
+       cpu_startup_entry(CPUHP_ONLINE);
 
        /* We should never reach here! */
        BUG();
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 537eb66..c025ffc 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -127,6 +127,8 @@ void __cpuinit smp_callin(void)
 
        /* idle thread is expected to have preempt disabled */
        preempt_disable();
+
+       cpu_startup_entry(CPUHP_ONLINE);
 }
 
 void cpu_panic(void)
diff --git a/arch/sparc/kernel/trampoline_64.S 
b/arch/sparc/kernel/trampoline_64.S
index da1b781..2e973a2 100644
--- a/arch/sparc/kernel/trampoline_64.S
+++ b/arch/sparc/kernel/trampoline_64.S
@@ -407,8 +407,7 @@ after_lock_tlb:
 
        call            smp_callin
         nop
-       call            cpu_idle
-        mov            0, %o0
+
        call            cpu_panic
         nop
 1:     b,a,pt          %xcc, 1b
--
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