cpuidle: create bootparam "cpuidle.off=1"

useful for disabling cpuidle to fall back
to architecture-default idle loop

cpuidle drivers and governors will fail to register.
on x86 they'll say so:

intel_idle: intel_idle yielding to (null)
ACPI: acpi_idle yielding to (null)

Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/cpuidle/governor.c b/drivers/cpuidle/governor.c
index 724c164d31c9..ea2f8e7aa24a 100644
--- a/drivers/cpuidle/governor.c
+++ b/drivers/cpuidle/governor.c
@@ -81,6 +81,9 @@ int cpuidle_register_governor(struct cpuidle_governor *gov)
         if (!gov || !gov->select)
                 return -EINVAL;
 
+        if (cpuidle_disabled())
+                return -ENODEV;
+
         mutex_lock(&cpuidle_lock);
         if (__cpuidle_find_governor(gov->name) == NULL) {
                 ret = 0;