[POWERPC] PS3: Save power in busy loops on halt

PS3 save power on halt:
- Replace infinite busy loops by smarter loops calling
lv1_pause() to save power.
- Add ps3_halt() and ps3_sys_manager_halt().
- Add __noreturn annotations.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Geoff Levand <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/platforms/ps3/setup.c

···
 	ps3_sys_manager_power_off(); /* never returns */
 }
 
+static void ps3_halt(void)
+{
+	DBG("%s:%d\n", __func__, __LINE__);
+
+	smp_send_stop();
+	ps3_sys_manager_halt(); /* never returns */
+}
+
 static void ps3_panic(char *str)
 {
 	DBG("%s:%d %s\n", __func__, __LINE__, str);
···
 	printk("   Please press POWER button.\n");
 	printk("\n");
 
-	while(1);
+	while(1)
+		lv1_pause(1);
 }
 
 #if defined(CONFIG_FB_PS3) || defined(CONFIG_FB_PS3_MODULE) || \
···
 	.progress			= ps3_progress,
 	.restart			= ps3_restart,
 	.power_off			= ps3_power_off,
+	.halt				= ps3_halt,
 #if defined(CONFIG_KEXEC)
 	.kexec_cpu_down			= ps3_kexec_cpu_down,
 	.machine_kexec			= default_machine_kexec,

drivers/ps3/ps3-sys-manager.c

···
 #include <linux/reboot.h>
 
 #include <asm/firmware.h>
+#include <asm/lv1call.h>
 #include <asm/ps3.h>
 
 #include "vuart.h"
···
 	return -EIO;
 }
 
+static void ps3_sys_manager_fin(struct ps3_system_bus_device *dev)
+{
+	ps3_sys_manager_send_request_shutdown(dev);
+
+	pr_emerg("System Halted, OK to turn off power\n");
+
+	while (ps3_sys_manager_handle_msg(dev)) {
+		/* pause until next DEC interrupt */
+		lv1_pause(0);
+	}
+
+	while (1) {
+		/* pause, ignoring DEC interrupt */
+		lv1_pause(1);
+	}
+}
+
 /**
  * ps3_sys_manager_final_power_off - The final platform machine_power_off routine.
  *
···
 
 	ps3_sys_manager_send_next_op(dev, PS3_SM_NEXT_OP_SYS_SHUTDOWN,
 		PS3_SM_WAKE_DEFAULT);
-	ps3_sys_manager_send_request_shutdown(dev);
 
-	pr_emerg("System Halted, OK to turn off power\n");
-
-	while (1)
-		ps3_sys_manager_handle_msg(dev);
+	ps3_sys_manager_fin(dev);
 }
 
 /**
···
 	ps3_sys_manager_send_attr(dev, 0);
 	ps3_sys_manager_send_next_op(dev, PS3_SM_NEXT_OP_SYS_REBOOT,
 		PS3_SM_WAKE_DEFAULT);
-	ps3_sys_manager_send_request_shutdown(dev);
 
-	pr_emerg("System Halted, OK to turn off power\n");
-
-	while (1)
-		ps3_sys_manager_handle_msg(dev);
+	ps3_sys_manager_fin(dev);
 }
 
 /**

drivers/ps3/sys-manager-core.c

···
  */
 
 #include <linux/kernel.h>
+#include <asm/lv1call.h>
 #include <asm/ps3.h>
 
 /**
···
 	if (ps3_sys_manager_ops.power_off)
 		ps3_sys_manager_ops.power_off(ps3_sys_manager_ops.dev);
 
-	printk(KERN_EMERG "System Halted, OK to turn off power\n");
-	local_irq_disable();
-	while (1)
-		(void)0;
+	ps3_sys_manager_halt();
 }
 
 void ps3_sys_manager_restart(void)
···
 	if (ps3_sys_manager_ops.restart)
 		ps3_sys_manager_ops.restart(ps3_sys_manager_ops.dev);
 
-	printk(KERN_EMERG "System Halted, OK to turn off power\n");
+	ps3_sys_manager_halt();
+}
+
+void ps3_sys_manager_halt(void)
+{
+	pr_emerg("System Halted, OK to turn off power\n");
 	local_irq_disable();
 	while (1)
-		(void)0;
+		lv1_pause(1);
 }
+

include/asm-powerpc/ps3.h

···
 };
 
 void ps3_sys_manager_register_ops(const struct ps3_sys_manager_ops *ops);
-void ps3_sys_manager_power_off(void);
-void ps3_sys_manager_restart(void);
+void __noreturn ps3_sys_manager_power_off(void);
+void __noreturn ps3_sys_manager_restart(void);
+void __noreturn ps3_sys_manager_halt(void);
 
 struct ps3_prealloc {
     const char *name;