[SPARC]: Make APC idle a boot time cmdline option.

arch/sparc/kernel/apc.c

@@ -22,7 +22,6 @@
 /* Debugging
  * 
  * #define APC_DEBUG_LED
- * #define APC_NO_IDLE
  */
 
 #define APC_MINOR	MISC_DYNAMIC_MINOR
@@ -31,10 +30,27 @@
 
 volatile static u8 *regs; 
 static int apc_regsize;
+static int apc_no_idle __initdata = 0;
 
 #define apc_readb(offs)			(sbus_readb(regs+offs))
 #define apc_writeb(val, offs) 	(sbus_writeb(val, regs+offs))
 
+/* Specify "apc=noidle" on the kernel command line to 
+ * disable APC CPU standby support.  Certain prototype
+ * systems (SPARCstation-Fox) do not play well with APC
+ * CPU idle, so disable this if your system has APC and 
+ * crashes randomly.
+ */
+static int __init apc_setup(char *str) 
+{
+	if(!strncmp(str, "noidle", strlen("noidle"))) {
+		apc_no_idle = 1;
+		return 1;
+	}
+	return 0;
+}
+__setup("apc=", apc_setup);
+
 /* 
  * CPU idle callback function
  * See .../arch/sparc/kernel/process.c
@@ -127,6 +143,7 @@ static int __init apc_probe(void)
 	struct sbus_bus *sbus = NULL;
 	struct sbus_dev *sdev = NULL;
 	int iTmp = 0;
+
 	for_each_sbus(sbus) {
 		for_each_sbusdev(sdev, sbus) {
 			if (!strcmp(sdev->prom_name, APC_OBPNAME)) {
@@ -155,12 +172,12 @@ static int __init apc_probe(void)
 		return -ENODEV;
 	}
 
-#ifndef APC_NO_IDLE	
 	/* Assign power management IDLE handler */
-	pm_idle = apc_swift_idle;	
-#endif
+	if(!apc_no_idle)
+		pm_idle = apc_swift_idle;	
 
-	printk(KERN_INFO "%s: power management initialized\n", APC_DEVNAME);
+	printk(KERN_INFO "%s: power management initialized%s\n", 
+		APC_DEVNAME, apc_no_idle ? " (CPU idle disabled)" : "");
 	return 0;
 }
 
@@ -169,3 +186,4 @@ static int __init apc_probe(void)
  * initialized, so we install ourselves thusly:
  */
 __initcall(apc_probe);
+