drivers: cpuidle: Add status property to ARM idle states

On some platforms the device tree bindings must provide the kernel
with a status flag for idle states, that defines whether the idle
state is operational or not in the current configuration.

This patch adds a status property to the ARM idle states compliant
with ePAPR v1.1 and updates the DT parsing code accordingly.

Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

2 files changed, 17 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/arm/idle-states.txt b/Documentation/devicetree/bindings/arm/idle-states.txt
index 37375c7f3ccc..5e5151130c20 100644
--- a/Documentation/devicetree/bindings/arm/idle-states.txt
+++ b/Documentation/devicetree/bindings/arm/idle-states.txt
@@ -317,6 +317,20 @@ follows:
                             In such systems entry-latency-us + exit-latency-us
                             will exceed wakeup-latency-us by this duration.
 
+        - status:
+                Usage: Optional
+                Value type: <string>
+                Definition: A standard device tree property [5] that indicates
+                            the operational status of an idle-state.
+                            If present, it shall be:
+                            "okay": to indicate that the idle state is
+                                    operational.
+                            "disabled": to indicate that the idle state has
+                                        been disabled in firmware so it is not
+                                        operational.
+                            If the property is not present the idle-state must
+                            be considered operational.
+
         In addition to the properties listed above, a state node may require
         additional properties specifics to the entry-method defined in the
         idle-states node, please refer to the entry-method bindings
diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c
index 52f4d11bbf3f..22840f40283c 100644
--- a/drivers/cpuidle/dt_idle_states.c
+++ b/drivers/cpuidle/dt_idle_states.c
@@ -169,6 +169,9 @@ int dt_init_idle_driver(struct cpuidle_driver *drv,
                 if (!state_node)
                         break;
 
+                if (!of_device_is_available(state_node))
+                        continue;
+
                 if (!idle_state_valid(state_node, i, cpumask)) {
                         pr_warn("%s idle state not valid, bailing out\n",
                                 state_node->full_name);