[PATCH] PM / devfreq: Add missing function description and rename static functions

From: Chanwoo Choi
Date: Mon Jan 06 2020 - 20:28:40 EST

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Rename internal function name used by devfreq core without 'devfreq_'
prefix in order to separate them from the exported functions.
And add missing function description for improving the readability.

Lastly, add the comments of devfreq_add_device to increase
the understanding of behavior of devfreq_add_device.

Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
---
drivers/devfreq/devfreq.c | 81 +++++++++++++++++++++++++++++++--------
1 file changed, 64 insertions(+), 17 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index acd21345a070..254f11b31824 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -48,7 +48,7 @@ static LIST_HEAD(devfreq_list);
static DEFINE_MUTEX(devfreq_list_lock);

/**
- * find_device_devfreq() - find devfreq struct using device pointer
+ * find_device_devfreq() - Find devfreq struct using device pointer
* @dev: device pointer used to lookup device devfreq.
*
* Search the list of device devfreqs and return the matched device's
@@ -73,6 +73,13 @@ static struct devfreq *find_device_devfreq(struct device *dev)
return ERR_PTR(-ENODEV);
}

+/**
+ * find_available_min_freq() - Find available min frequency via OPP interface
+ * @devfreq: the devfreq instance
+ *
+ * Find available minimum frequency among the active OPP entries
+ * because could either enable or disable the frequency by using OPP interface.
+ */
static unsigned long find_available_min_freq(struct devfreq *devfreq)
{
struct dev_pm_opp *opp;
@@ -87,6 +94,13 @@ static unsigned long find_available_min_freq(struct devfreq *devfreq)
return min_freq;
}

+/**
+ * find_available_max_freq() - Find available max frequency via OPP interface
+ * @devfreq: the devfreq instance
+ *
+ * Find available maximum frequency among the active OPP entries
+ * because could either enable or disable the frequency by using OPP interface.
+ */
static unsigned long find_available_max_freq(struct devfreq *devfreq)
{
struct dev_pm_opp *opp;
@@ -150,11 +164,11 @@ static void get_freq_range(struct devfreq *devfreq,
}

/**
- * devfreq_get_freq_level() - Lookup freq_table for the frequency
+ * get_freq_level() - Lookup freq_table for the frequency
* @devfreq: the devfreq instance
* @freq: the target frequency
*/
-static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
+static int get_freq_level(struct devfreq *devfreq, unsigned long freq)
{
int lev;

@@ -165,6 +179,13 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
return -EINVAL;
}

+/**
+ * set_freq_table() - Fill out the freq_table of devfreq instance
+ * @devfreq: the devfreq instance
+ *
+ * If freq_table array is NULL, fill out the freq_table array
+ * by using OPP interface because OPP is mandatory.
+ */
static int set_freq_table(struct devfreq *devfreq)
{
struct devfreq_dev_profile *profile = devfreq->profile;
@@ -218,7 +239,7 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
if (!devfreq->previous_freq)
goto out;

- prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
+ prev_lev = get_freq_level(devfreq, devfreq->previous_freq);
if (prev_lev < 0) {
ret = prev_lev;
goto out;
@@ -227,7 +248,7 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
devfreq->stats.time_in_state[prev_lev] +=
cur_time - devfreq->stats.last_update;

- lev = devfreq_get_freq_level(devfreq, freq);
+ lev = get_freq_level(devfreq, freq);
if (lev < 0) {
ret = lev;
goto out;
@@ -246,7 +267,7 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
EXPORT_SYMBOL(devfreq_update_status);

/**
- * find_devfreq_governor() - find devfreq governor from name
+ * find_devfreq_governor() - Find devfreq governor from name
* @name: name of the governor
*
* Search the list of devfreq governors and return the matched
@@ -314,8 +335,17 @@ static struct devfreq_governor *try_then_request_governor(const char *name)
return governor;
}

-static int devfreq_notify_transition(struct devfreq *devfreq,
- struct devfreq_freqs *freqs, unsigned int state)
+/**
+ * notify_transition() - Send the transition notification
+ * @name: name of the governor
+ * @freqs: the data containing the both old and new frequency
+ * @state: the kind of notification
+ *
+ * Send the transition notification to the registered receivers
+ * in order to inform the frequency change.
+ */
+static int notify_transition(struct devfreq *devfreq,
+ struct devfreq_freqs *freqs, unsigned int state)
{
if (!devfreq)
return -EINVAL;
@@ -337,8 +367,17 @@ static int devfreq_notify_transition(struct devfreq *devfreq,
return 0;
}

-static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
- u32 flags)
+/**
+ * set_target() - Set target frequency of devfreq instance
+ * @devfreq: the devfreq instance
+ * @new_freq: the target frequency
+ * @flags: flags handed from devfreq framework
+ *
+ * Set the target frequency of which is decided by governor
+ * and then is adjusted with constraints.
+ */
+static int set_target(struct devfreq *devfreq,
+ unsigned long new_freq, u32 flags)
{
struct devfreq_freqs freqs;
unsigned long cur_freq;
@@ -351,17 +390,17 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,

freqs.old = cur_freq;
freqs.new = new_freq;
- devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
+ notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);

err = devfreq->profile->target(devfreq->dev.parent, &new_freq, flags);
if (err) {
freqs.new = cur_freq;
- devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+ notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
return err;
}

freqs.new = new_freq;
- devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
+ notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);

if (devfreq_update_status(devfreq, new_freq))
dev_err(&devfreq->dev,
@@ -413,7 +452,7 @@ int update_devfreq(struct devfreq *devfreq)
flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
}

- return devfreq_set_target(devfreq, freq, flags);
+ return set_target(devfreq, freq, flags);

}
EXPORT_SYMBOL(update_devfreq);
@@ -421,7 +460,6 @@ EXPORT_SYMBOL(update_devfreq);
/**
* devfreq_monitor() - Periodically poll devfreq objects.
* @work: the work struct used to run devfreq_monitor periodically.
- *
*/
static void devfreq_monitor(struct work_struct *work)
{
@@ -739,11 +777,13 @@ struct devfreq *devfreq_add_device(struct device *dev,
static atomic_t devfreq_no = ATOMIC_INIT(-1);
int err = 0;

+ /* Check the parameter is valid */
if (!dev || !profile || !governor_name) {
dev_err(dev, "%s: Invalid parameters.\n", __func__);
return ERR_PTR(-EINVAL);
}

+ /* Check the device is already added or not */
mutex_lock(&devfreq_list_lock);
devfreq = find_device_devfreq(dev);
mutex_unlock(&devfreq_list_lock);
@@ -754,6 +794,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
goto err_out;
}

+ /* Initialize the devfreq instance */
devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
if (!devfreq) {
err = -ENOMEM;
@@ -798,6 +839,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
atomic_set(&devfreq->suspend_count, 0);

+ /* Register a device for devfreq instance */
dev_set_name(&devfreq->dev, "devfreq%d",
atomic_inc_return(&devfreq_no));
err = device_register(&devfreq->dev);
@@ -807,6 +849,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
goto err_out;
}

+ /* Initialize the statistics of devfreq device behavior */
devfreq->stats.trans_table = devm_kzalloc(&devfreq->dev,
array3_size(sizeof(unsigned int),
devfreq->profile->max_state,
@@ -831,10 +874,12 @@ struct devfreq *devfreq_add_device(struct device *dev,
devfreq->stats.total_trans = 0;
devfreq->stats.last_update = get_jiffies_64();

+ /* Initialize notifiers for informing the transition of devfreq */
srcu_init_notifier_head(&devfreq->transition_notifier_list);

mutex_unlock(&devfreq->lock);

+ /* Initialize PM QoS for applying the constraints */
err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req,
DEV_PM_QOS_MIN_FREQUENCY, 0);
if (err < 0)
@@ -859,6 +904,7 @@ struct devfreq *devfreq_add_device(struct device *dev,

mutex_lock(&devfreq_list_lock);

+ /* Find the devfreq governor and start */
governor = try_then_request_governor(devfreq->governor_name);
if (IS_ERR(governor)) {
dev_err(dev, "%s: Unable to find governor for the device\n",
@@ -876,6 +922,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
goto err_init;
}

+ /* Add the devfreq instance to global devfreq list finally */
list_add(&devfreq->node, &devfreq_list);

mutex_unlock(&devfreq_list_lock);
@@ -1076,7 +1123,7 @@ int devfreq_suspend_device(struct devfreq *devfreq)

if (devfreq->suspend_freq) {
mutex_lock(&devfreq->lock);
- ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
+ ret = set_target(devfreq, devfreq->suspend_freq, 0);
mutex_unlock(&devfreq->lock);
if (ret)
return ret;
@@ -1106,7 +1153,7 @@ int devfreq_resume_device(struct devfreq *devfreq)

if (devfreq->resume_freq) {
mutex_lock(&devfreq->lock);
- ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
+ ret = set_target(devfreq, devfreq->resume_freq, 0);
mutex_unlock(&devfreq->lock);
if (ret)
return ret;
--
2.17.1

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