cpufreq: arm_big_little: reconfigure switcher behavior at run time

The b.L switcher can be turned on/off at run time.  It is therefore
necessary to change the cpufreq driver behavior accordingly.

The driver must be unregistered/registered with the cpufreq core
to reconfigure freq tables for the virtual or actual CPUs. This is
accomplished via the b.L switcher notifier callback.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 51 insertions, 3 deletions

diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 9986f7912328..71f1af93b585 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -40,9 +40,12 @@
 #define MAX_CLUSTERS    2
 
 #ifdef CONFIG_BL_SWITCHER
-#define is_bL_switching_enabled()       true
+static bool bL_switching_enabled;
+#define is_bL_switching_enabled()       bL_switching_enabled
+#define set_switching_enabled(x)        (bL_switching_enabled = (x))
 #else
 #define is_bL_switching_enabled()       false
+#define set_switching_enabled(x)        do { } while (0)
 #endif
 
 #define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
@@ -508,6 +511,38 @@ static struct cpufreq_driver bL_cpufreq_driver = {
         .attr                   = cpufreq_generic_attr,
 };
 
+static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
+                                        unsigned long action, void *_arg)
+{
+        pr_debug("%s: action: %ld\n", __func__, action);
+
+        switch (action) {
+        case BL_NOTIFY_PRE_ENABLE:
+        case BL_NOTIFY_PRE_DISABLE:
+                cpufreq_unregister_driver(&bL_cpufreq_driver);
+                break;
+
+        case BL_NOTIFY_POST_ENABLE:
+                set_switching_enabled(true);
+                cpufreq_register_driver(&bL_cpufreq_driver);
+                break;
+
+        case BL_NOTIFY_POST_DISABLE:
+                set_switching_enabled(false);
+                cpufreq_register_driver(&bL_cpufreq_driver);
+                break;
+
+        default:
+                return NOTIFY_DONE;
+        }
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block bL_switcher_notifier = {
+        .notifier_call = bL_cpufreq_switcher_notifier,
+};
+
 int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 {
         int ret, i;
@@ -525,6 +560,9 @@ int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 
         arm_bL_ops = ops;
 
+        ret = bL_switcher_get_enabled();
+        set_switching_enabled(ret);
+
         for (i = 0; i < MAX_CLUSTERS; i++)
                 mutex_init(&cluster_lock[i]);
 
@@ -534,10 +572,17 @@ int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
                                 __func__, ops->name, ret);
                 arm_bL_ops = NULL;
         } else {
-                pr_info("%s: Registered platform driver: %s\n", __func__,
-                                ops->name);
+                ret = bL_switcher_register_notifier(&bL_switcher_notifier);
+                if (ret) {
+                        cpufreq_unregister_driver(&bL_cpufreq_driver);
+                        arm_bL_ops = NULL;
+                } else {
+                        pr_info("%s: Registered platform driver: %s\n",
+                                        __func__, ops->name);
+                }
         }
 
+        bL_switcher_put_enabled();
         return ret;
 }
 EXPORT_SYMBOL_GPL(bL_cpufreq_register);
@@ -550,7 +595,10 @@ void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops)
                 return;
         }
 
+        bL_switcher_get_enabled();
+        bL_switcher_unregister_notifier(&bL_switcher_notifier);
         cpufreq_unregister_driver(&bL_cpufreq_driver);
+        bL_switcher_put_enabled();
         pr_info("%s: Un-registered platform driver: %s\n", __func__,
                         arm_bL_ops->name);
         arm_bL_ops = NULL;