cpuidle: Introduce cpuidle_driver_state_disabled() for driver quirks

Commit 99e98d3 ("cpuidle: Consolidate disabled state checks")
overlooked the fact that the imx6q and tegra20 cpuidle drivers use
the "disabled" field in struct cpuidle_state for quirks which trigger
after the initialization of cpuidle, so reading the initial value of
that field is not sufficient for those drivers.

In order to allow them to implement the quirks without using the
"disabled" field in struct cpuidle_state, introduce a new helper
function and modify them to use it.

Fixes: 99e98d3 ("cpuidle: Consolidate disabled state checks")
Reported-by: Len Brown <lenb@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/arm/mach-imx/cpuidle-imx6q.c

@@ -62,13 +62,13 @@ static struct cpuidle_driver imx6q_cpuidle_driver = {
  */
 void imx6q_cpuidle_fec_irqs_used(void)
 {
-	imx6q_cpuidle_driver.states[1].disabled = true;
+	cpuidle_driver_state_disabled(&imx6q_cpuidle_driver, 1, true);
 }
 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_used);
 
 void imx6q_cpuidle_fec_irqs_unused(void)
 {
-	imx6q_cpuidle_driver.states[1].disabled = false;
+	cpuidle_driver_state_disabled(&imx6q_cpuidle_driver, 1, false);
 }
 EXPORT_SYMBOL_GPL(imx6q_cpuidle_fec_irqs_unused);
 

arch/arm/mach-tegra/cpuidle-tegra20.c

@@ -203,7 +203,7 @@ void tegra20_cpuidle_pcie_irqs_in_use(void)
 {
 	pr_info_once(
 		"Disabling cpuidle LP2 state, since PCIe IRQs are in use\n");
-	tegra_idle_driver.states[1].disabled = true;
+	cpuidle_driver_state_disabled(&tegra_idle_driver, 1, true);
 }
 
 int __init tegra20_cpuidle_init(void)

drivers/cpuidle/driver.c

@@ -389,3 +389,31 @@ void cpuidle_driver_unref(void)
 
 	spin_unlock(&cpuidle_driver_lock);
 }
+
+/**
+ * cpuidle_driver_state_disabled - Disable or enable an idle state
+ * @drv: cpuidle driver owning the state
+ * @idx: State index
+ * @disable: Whether or not to disable the state
+ */
+void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
+				 bool disable)
+{
+	unsigned int cpu;
+
+	mutex_lock(&cpuidle_lock);
+
+	for_each_cpu(cpu, drv->cpumask) {
+		struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
+
+		if (!dev)
+			continue;
+
+		if (disable)
+			dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
+		else
+			dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
+	}
+
+	mutex_unlock(&cpuidle_lock);
+}

include/linux/cpuidle.h

@@ -149,6 +149,8 @@ extern int cpuidle_register_driver(struct cpuidle_driver *drv);
 extern struct cpuidle_driver *cpuidle_get_driver(void);
 extern struct cpuidle_driver *cpuidle_driver_ref(void);
 extern void cpuidle_driver_unref(void);
+extern void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
+					bool disable);
 extern void cpuidle_unregister_driver(struct cpuidle_driver *drv);
 extern int cpuidle_register_device(struct cpuidle_device *dev);
 extern void cpuidle_unregister_device(struct cpuidle_device *dev);
@@ -186,6 +188,8 @@ static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
 static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
 static inline struct cpuidle_driver *cpuidle_driver_ref(void) {return NULL; }
 static inline void cpuidle_driver_unref(void) {}
+static inline void cpuidle_driver_state_disabled(struct cpuidle_driver *drv,
+					       int idx, bool disable) { }
 static inline void cpuidle_unregister_driver(struct cpuidle_driver *drv) { }
 static inline int cpuidle_register_device(struct cpuidle_device *dev)
 {return -ENODEV; }