PM / devfreq: Add new DEVFREQ_TRANSITION_NOTIFIER notifier

This patch adds the new DEVFREQ_TRANSITION_NOTIFIER notifier to send
the notification when the frequency of device is changed.
This notifier has two state as following:
- DEVFREQ_PRECHANGE  : Notify it before chaning the frequency of device
- DEVFREQ_POSTCHANGE : Notify it after changed the frequency of device

And this patch adds the resourced-managed function to release the resource
automatically when error happen.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
[m.reichl and linux.amoon: Tested it on exynos4412-odroidu3 board]
Tested-by: Markus Reichl <m.reichl@fivetechno.de>
Tested-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

2 files changed, 220 insertions, 2 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 20a9422c2552..1d6c803804d5 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -189,6 +189,29 @@ static struct devfreq_governor *find_devfreq_governor(const char *name)
         return ERR_PTR(-ENODEV);
 }
 
+static int devfreq_notify_transition(struct devfreq *devfreq,
+                struct devfreq_freqs *freqs, unsigned int state)
+{
+        if (!devfreq)
+                return -EINVAL;
+
+        switch (state) {
+        case DEVFREQ_PRECHANGE:
+                srcu_notifier_call_chain(&devfreq->transition_notifier_list,
+                                DEVFREQ_PRECHANGE, freqs);
+                break;
+
+        case DEVFREQ_POSTCHANGE:
+                srcu_notifier_call_chain(&devfreq->transition_notifier_list,
+                                DEVFREQ_POSTCHANGE, freqs);
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
 /* Load monitoring helper functions for governors use */
 
 /**
@@ -200,7 +223,8 @@ static struct devfreq_governor *find_devfreq_governor(const char *name)
  */
 int update_devfreq(struct devfreq *devfreq)
 {
-        unsigned long freq;
+        struct devfreq_freqs freqs;
+        unsigned long freq, cur_freq;
         int err = 0;
         u32 flags = 0;
 
@@ -234,10 +258,22 @@ int update_devfreq(struct devfreq *devfreq)
                 flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
         }
 
+        if (devfreq->profile->get_cur_freq)
+                devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
+        else
+                cur_freq = devfreq->previous_freq;
+
+        freqs.old = cur_freq;
+        freqs.new = freq;
+        devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
+
         err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
         if (err)
                 return err;
 
+        freqs.new = freq;
+        devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+
         if (devfreq->profile->freq_table)
                 if (devfreq_update_status(devfreq, freq))
                         dev_err(&devfreq->dev,
@@ -542,6 +578,8 @@ struct devfreq *devfreq_add_device(struct device *dev,
                 goto err_out;
         }
 
+        srcu_init_notifier_head(&devfreq->transition_notifier_list);
+
         mutex_unlock(&devfreq->lock);
 
         mutex_lock(&devfreq_list_lock);
@@ -1310,6 +1348,129 @@ void devm_devfreq_unregister_opp_notifier(struct device *dev,
 }
 EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);
 
+/**
+ * devfreq_register_notifier() - Register a driver with devfreq
+ * @devfreq:    The devfreq object.
+ * @nb:         The notifier block to register.
+ * @list:       DEVFREQ_TRANSITION_NOTIFIER.
+ */
+int devfreq_register_notifier(struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list)
+{
+        int ret = 0;
+
+        if (!devfreq)
+                return -EINVAL;
+
+        switch (list) {
+        case DEVFREQ_TRANSITION_NOTIFIER:
+                ret = srcu_notifier_chain_register(
+                                &devfreq->transition_notifier_list, nb);
+                break;
+        default:
+                ret = -EINVAL;
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL(devfreq_register_notifier);
+
+/*
+ * devfreq_unregister_notifier() - Unregister a driver with devfreq
+ * @devfreq:    The devfreq object.
+ * @nb:         The notifier block to be unregistered.
+ * @list:       DEVFREQ_TRANSITION_NOTIFIER.
+ */
+int devfreq_unregister_notifier(struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list)
+{
+        int ret = 0;
+
+        if (!devfreq)
+                return -EINVAL;
+
+        switch (list) {
+        case DEVFREQ_TRANSITION_NOTIFIER:
+                ret = srcu_notifier_chain_unregister(
+                                &devfreq->transition_notifier_list, nb);
+                break;
+        default:
+                ret = -EINVAL;
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL(devfreq_unregister_notifier);
+
+struct devfreq_notifier_devres {
+        struct devfreq *devfreq;
+        struct notifier_block *nb;
+        unsigned int list;
+};
+
+static void devm_devfreq_notifier_release(struct device *dev, void *res)
+{
+        struct devfreq_notifier_devres *this = res;
+
+        devfreq_unregister_notifier(this->devfreq, this->nb, this->list);
+}
+
+/**
+ * devm_devfreq_register_notifier()
+        - Resource-managed devfreq_register_notifier()
+ * @dev:        The devfreq user device. (parent of devfreq)
+ * @devfreq:    The devfreq object.
+ * @nb:         The notifier block to be unregistered.
+ * @list:       DEVFREQ_TRANSITION_NOTIFIER.
+ */
+int devm_devfreq_register_notifier(struct device *dev,
+                                struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list)
+{
+        struct devfreq_notifier_devres *ptr;
+        int ret;
+
+        ptr = devres_alloc(devm_devfreq_notifier_release, sizeof(*ptr),
+                                GFP_KERNEL);
+        if (!ptr)
+                return -ENOMEM;
+
+        ret = devfreq_register_notifier(devfreq, nb, list);
+        if (ret) {
+                devres_free(ptr);
+                return ret;
+        }
+
+        ptr->devfreq = devfreq;
+        ptr->nb = nb;
+        ptr->list = list;
+        devres_add(dev, ptr);
+
+        return 0;
+}
+EXPORT_SYMBOL(devm_devfreq_register_notifier);
+
+/**
+ * devm_devfreq_unregister_notifier()
+        - Resource-managed devfreq_unregister_notifier()
+ * @dev:        The devfreq user device. (parent of devfreq)
+ * @devfreq:    The devfreq object.
+ * @nb:         The notifier block to be unregistered.
+ * @list:       DEVFREQ_TRANSITION_NOTIFIER.
+ */
+void devm_devfreq_unregister_notifier(struct device *dev,
+                                struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list)
+{
+        WARN_ON(devres_release(dev, devm_devfreq_notifier_release,
+                               devm_devfreq_dev_match, devfreq));
+}
+EXPORT_SYMBOL(devm_devfreq_unregister_notifier);
+
 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 MODULE_DESCRIPTION("devfreq class support");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index aa0b8424ebc3..98c699304e12 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -19,6 +19,13 @@
 
 #define DEVFREQ_NAME_LEN 16
 
+/* DEVFREQ notifier interface */
+#define DEVFREQ_TRANSITION_NOTIFIER     (0)
+
+/* Transition notifiers of DEVFREQ_TRANSITION_NOTIFIER */
+#define DEVFREQ_PRECHANGE               (0)
+#define DEVFREQ_POSTCHANGE              (1)
+
 struct devfreq;
 
 /**
@@ -143,6 +150,7 @@ struct devfreq_governor {
  * @trans_table:        Statistics of devfreq transitions
  * @time_in_state:      Statistics of devfreq states
  * @last_stat_updated:  The last time stat updated
+ * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
  *
  * This structure stores the devfreq information for a give device.
  *
@@ -177,6 +185,13 @@ struct devfreq {
         unsigned int *trans_table;
         unsigned long *time_in_state;
         unsigned long last_stat_updated;
+
+        struct srcu_notifier_head transition_notifier_list;
+};
+
+struct devfreq_freqs {
+        unsigned long old;
+        unsigned long new;
 };
 
 #if defined(CONFIG_PM_DEVFREQ)
@@ -207,7 +222,20 @@ extern int devm_devfreq_register_opp_notifier(struct device *dev,
                                               struct devfreq *devfreq);
 extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
                                                 struct devfreq *devfreq);
-
+extern int devfreq_register_notifier(struct devfreq *devfreq,
+                                        struct notifier_block *nb,
+                                        unsigned int list);
+extern int devfreq_unregister_notifier(struct devfreq *devfreq,
+                                        struct notifier_block *nb,
+                                        unsigned int list);
+extern int devm_devfreq_register_notifier(struct device *dev,
+                                struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list);
+extern void devm_devfreq_unregister_notifier(struct device *dev,
+                                struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list);
 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
                                                 int index);
 
@@ -310,6 +338,35 @@ static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
 {
 }
 
+static inline int devfreq_register_notifier(struct devfreq *devfreq,
+                                        struct notifier_block *nb,
+                                        unsigned int list)
+{
+        return 0;
+}
+
+static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
+                                        struct notifier_block *nb,
+                                        unsigned int list)
+{
+        return 0;
+}
+
+static inline int devm_devfreq_register_notifier(struct device *dev,
+                                struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list)
+{
+        return 0;
+}
+
+static inline void devm_devfreq_unregister_notifier(struct device *dev,
+                                struct devfreq *devfreq,
+                                struct notifier_block *nb,
+                                unsigned int list)
+{
+}
+
 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
                                                         int index)
 {