sparc: Use generic idle loop

Add generic cpu_idle support

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

sparc64:
- smp_callin() now include cpu_startup_entry() call so we can
  skip calling cpu_idle from assembler
- add arch_cpu_idle() and arch_cpu_idle_dead()

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: torvalds@linux-foundation.org
Cc: rusty@rustcorp.com.au
Cc: paulmck@linux.vnet.ibm.com
Cc: peterz@infradead.org
Cc: magnus.damm@gmail.com
Acked-by: David Miller <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20130411193850.GA2330@merkur.ravnborg.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

7 files changed, 24 insertions, 57 deletions

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 3d361f236308..ee5eacc5a649 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -37,6 +37,7 @@ config SPARC
         select GENERIC_SMP_IDLE_THREAD
         select GENERIC_CMOS_UPDATE
         select GENERIC_CLOCKEVENTS
+        select GENERIC_IDLE_LOOP
         select GENERIC_STRNCPY_FROM_USER
         select GENERIC_STRNLEN_USER
         select MODULES_USE_ELF_RELA
diff --git a/arch/sparc/kernel/hvtramp.S b/arch/sparc/kernel/hvtramp.S
index 9365432904d6..605c960b2fa6 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 62eede13831a..c85241006e32 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -64,23 +64,12 @@ 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)
+/* Idle loop support. */
+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)();
+        local_irq_enable();
 }
 
 /* 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 cdb80b2adbe0..9fbf0d14a361 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -52,20 +52,17 @@
 
 #include "kstack.h"
 
-static void sparc64_yield(int cpu)
+/* Idle loop support on sparc64. */
+void arch_cpu_idle(void)
 {
         if (tlb_type != hypervisor) {
                 touch_nmi_watchdog();
-                return;
-        }
-
-        clear_thread_flag(TIF_POLLING_NRFLAG);
-        smp_mb__after_clear_bit();
-
-        while (!need_resched() && !cpu_is_offline(cpu)) {
+        } else {
                 unsigned long pstate;
 
-                /* Disable interrupts. */
+                /* The sun4v sleeping code requires that we have PSTATE.IE cleared over
+                 * the cpu sleep hypervisor call.
+                 */
                 __asm__ __volatile__(
                         "rdpr %%pstate, %0\n\t"
                         "andn %0, %1, %0\n\t"
@@ -73,7 +70,7 @@ static void sparc64_yield(int cpu)
                         : "=&r" (pstate)
                         : "i" (PSTATE_IE));
 
-                if (!need_resched() && !cpu_is_offline(cpu))
+                if (!need_resched() && !cpu_is_offline(smp_processor_id()))
                         sun4v_cpu_yield();
 
                 /* Re-enable interrupts. */
@@ -84,36 +81,16 @@ static void sparc64_yield(int cpu)
                         : "=&r" (pstate)
                         : "i" (PSTATE_IE));
         }
-
-        set_thread_flag(TIF_POLLING_NRFLAG);
+        local_irq_enable();
 }
 
-/* The idle loop on sparc64. */
-void cpu_idle(void)
-{
-        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();
-        }
+void arch_cpu_idle_dead()
+{
+        sched_preempt_enable_no_resched();
+        cpu_play_dead();
 }
+#endif
 
 #ifdef CONFIG_COMPAT
 static void show_regwindow32(struct pt_regs *regs)
diff --git a/arch/sparc/kernel/smp_32.c b/arch/sparc/kernel/smp_32.c
index 9e7e6d718367..e3f2b81c23f1 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 537eb66abd06..c025ffce7a40 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 da1b781b5e65..2e973a26fbda 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