[Skiboot] [PATCH 25/34] cpu: Add cpu_idle() which we call when waiting for a job

[Benjamin Herrenschmidt]

For now a simple generic implementation using cpu_relax()

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
 core/cpu.c    | 18 ++++++++++++++++++
 core/init.c   | 20 ++++----------------
 include/cpu.h |  7 +++++++
 3 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/core/cpu.c b/core/cpu.c
index 6dd841c..15c8fb9 100644
--- a/core/cpu.c
+++ b/core/cpu.c
@@ -212,6 +212,24 @@ void cpu_process_jobs(void)
 	unlock(&cpu->job_lock);
 }
 
+static void cpu_idle_default(enum cpu_wake_cause wake_on __unused)
+{
+	/* Maybe do something better for simulators ? */
+	cpu_relax();
+	cpu_relax();
+	cpu_relax();
+	cpu_relax();
+}
+
+void cpu_idle(enum cpu_wake_cause wake_on)
+{
+	switch(proc_gen) {
+	default:
+		cpu_idle_default(wake_on);
+		break;
+	}
+}
+
 void cpu_process_local_jobs(void)
 {
 	struct cpu_thread *cpu = first_available_cpu();
diff --git a/core/init.c b/core/init.c
index bba7d96..237ccfb 100644
--- a/core/init.c
+++ b/core/init.c
@@ -866,22 +866,10 @@ void __noreturn __secondary_cpu_entry(void)
 
 	/* Wait for work to do */
 	while(true) {
-		int i;
-
-		/* Process pending jobs on this processor */
-		cpu_process_jobs();
-
-		/* Relax a bit to give the simulator some breathing space */
-		i = 1000;
-		smt_very_low();
-		asm volatile("mtctr %0;\n"
-			     "1: nop; nop; nop; nop;\n"
-			     "   nop; nop; nop; nop;\n"
-			     "   nop; nop; nop; nop;\n"
-			     "   nop; nop; nop; nop;\n"
-			     "   bdnz 1b"
-			     : : "r" (i) : "memory", "ctr");
-		smt_medium();
+		if (cpu_check_jobs(cpu))
+		    cpu_process_jobs();
+		else
+		    cpu_idle(cpu_wake_on_job);
 	}
 }
 
diff --git a/include/cpu.h b/include/cpu.h
index 1188168..256fc5b 100644
--- a/include/cpu.h
+++ b/include/cpu.h
@@ -43,6 +43,11 @@ enum cpu_thread_state {
 struct cpu_job;
 struct xive_cpu_state;
 
+enum cpu_wake_cause {
+	cpu_wake_on_job,
+	cpu_wake_on_dec,
+};
+
 struct cpu_thread {
 	uint32_t			pir;
 	uint32_t			server_no;
@@ -253,4 +258,6 @@ static inline void cpu_give_self_os(void)
 extern unsigned long __attrconst cpu_stack_bottom(unsigned int pir);
 extern unsigned long __attrconst cpu_stack_top(unsigned int pir);
 
+extern void cpu_idle(enum cpu_wake_cause wake_on);
+
 #endif /* __CPU_H */
-- 
2.7.4