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Subject[PATCH v5 05/12] PM / devfreq: Add support for policy notifiers
Date
Policy notifiers are called before a frequency change and may narrow
the min/max frequency range in devfreq_policy, which is used to adjust
the target frequency if it is beyond this range.

Also add a few helpers:
- devfreq_verify_within_[dev_]limits()
- should be used by the notifiers for policy adjustments.
- dev_to_devfreq()
- lookup a devfreq strict from a device pointer

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
---
Changes in v5:
- none

Changes in v4:
- Fixed typo in commit message: devfreg => devfreq
- added 'Reviewed-by: Brian Norris <briannorris@chromium.org>' tag

Changes in v3:
- devfreq.h: fixed misspelling of struct devfreq_policy

Changes in v2:
- performance, powersave and simpleondemand governors don't need changes
with "PM / devfreq: Don't adjust to user limits in governors"
- formatting fixes
---
drivers/devfreq/devfreq.c | 48 ++++++++++++++++++++++-------
include/linux/devfreq.h | 65 +++++++++++++++++++++++++++++++++++++++
2 files changed, 102 insertions(+), 11 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 21604d6ae2b8..4cbaa7ad1972 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -72,6 +72,21 @@ static struct devfreq *find_device_devfreq(struct device *dev)
return ERR_PTR(-ENODEV);
}

+/**
+ * dev_to_devfreq() - find devfreq struct using device pointer
+ * @dev: device pointer used to lookup device devfreq.
+ */
+struct devfreq *dev_to_devfreq(struct device *dev)
+{
+ struct devfreq *devfreq;
+
+ mutex_lock(&devfreq_list_lock);
+ devfreq = find_device_devfreq(dev);
+ mutex_unlock(&devfreq_list_lock);
+
+ return devfreq;
+}
+
static unsigned long find_available_min_freq(struct devfreq *devfreq)
{
struct dev_pm_opp *opp;
@@ -269,20 +284,21 @@ int update_devfreq(struct devfreq *devfreq)
if (!policy->governor)
return -EINVAL;

+ policy->min = policy->devinfo.min_freq;
+ policy->max = policy->devinfo.max_freq;
+
+ srcu_notifier_call_chain(&devfreq->policy_notifier_list,
+ DEVFREQ_ADJUST, policy);
+
/* Reevaluate the proper frequency */
err = policy->governor->get_target_freq(devfreq, &freq);
if (err)
return err;

- /*
- * Adjust the frequency with user freq, QoS and available freq.
- *
- * List from the highest priority
- * max_freq
- * min_freq
- */
- max_freq = MIN(policy->devinfo.max_freq, policy->user.max_freq);
- min_freq = MAX(policy->devinfo.min_freq, policy->user.min_freq);
+ /* Adjust the frequency */
+
+ max_freq = MIN(policy->max, policy->user.max_freq);
+ min_freq = MAX(policy->min, policy->user.min_freq);

if (freq < min_freq) {
freq = min_freq;
@@ -645,6 +661,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
devfreq->last_stat_updated = jiffies;

srcu_init_notifier_head(&devfreq->transition_notifier_list);
+ srcu_init_notifier_head(&devfreq->policy_notifier_list);

mutex_unlock(&devfreq->lock);

@@ -1445,7 +1462,7 @@ 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.
+ * @list: DEVFREQ_TRANSITION_NOTIFIER or DEVFREQ_POLICY_NOTIFIER.
*/
int devfreq_register_notifier(struct devfreq *devfreq,
struct notifier_block *nb,
@@ -1461,6 +1478,10 @@ int devfreq_register_notifier(struct devfreq *devfreq,
ret = srcu_notifier_chain_register(
&devfreq->transition_notifier_list, nb);
break;
+ case DEVFREQ_POLICY_NOTIFIER:
+ ret = srcu_notifier_chain_register(
+ &devfreq->policy_notifier_list, nb);
+ break;
default:
ret = -EINVAL;
}
@@ -1473,7 +1494,7 @@ 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.
+ * @list: DEVFREQ_TRANSITION_NOTIFIER or DEVFREQ_POLICY_NOTIFIER.
*/
int devfreq_unregister_notifier(struct devfreq *devfreq,
struct notifier_block *nb,
@@ -1489,6 +1510,11 @@ int devfreq_unregister_notifier(struct devfreq *devfreq,
ret = srcu_notifier_chain_unregister(
&devfreq->transition_notifier_list, nb);
break;
+ case DEVFREQ_POLICY_NOTIFIER:
+ ret = srcu_notifier_chain_unregister(
+ &devfreq->policy_notifier_list, nb);
+ break;
+
default:
ret = -EINVAL;
}
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index 9bf23b976f4d..7c8dce96db73 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -33,6 +33,10 @@
#define DEVFREQ_PRECHANGE (0)
#define DEVFREQ_POSTCHANGE (1)

+#define DEVFREQ_POLICY_NOTIFIER 1
+
+#define DEVFREQ_ADJUST 0
+
struct devfreq;
struct devfreq_governor;

@@ -121,12 +125,16 @@ struct devfreq_freq_limits {

/**
* struct devfreq_policy - Devfreq policy
+ * @min: minimum frequency (adjustable by policy notifiers)
+ * @min: maximum frequency (adjustable by policy notifiers)
* @user: frequency limits requested by the user
* @devinfo: frequency limits of the device (available OPPs)
* @governor: method how to choose frequency based on the usage.
* @governor_name: devfreq governor name for use with this devfreq
*/
struct devfreq_policy {
+ unsigned long min;
+ unsigned long max;
struct devfreq_freq_limits user;
struct devfreq_freq_limits devinfo;
const struct devfreq_governor *governor;
@@ -155,6 +163,7 @@ struct devfreq_policy {
* @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
+ * @policy_notifier_list: list head of DEVFREQ_POLICY_NOTIFIER notifier
*
* This structure stores the devfreq information for a give device.
*
@@ -188,6 +197,7 @@ struct devfreq {
unsigned long last_stat_updated;

struct srcu_notifier_head transition_notifier_list;
+ struct srcu_notifier_head policy_notifier_list;
};

struct devfreq_freqs {
@@ -240,6 +250,45 @@ extern void devm_devfreq_unregister_notifier(struct device *dev,
extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
int index);

+/**
+ * devfreq_verify_within_limits() - Adjust a devfreq policy if needed to make
+ * sure its min/max values are within a
+ * specified range.
+ * @policy: the policy
+ * @min: the minimum frequency
+ * @max: the maximum frequency
+ */
+static inline void devfreq_verify_within_limits(struct devfreq_policy *policy,
+ unsigned int min, unsigned int max)
+{
+ if (policy->min < min)
+ policy->min = min;
+ if (policy->max < min)
+ policy->max = min;
+ if (policy->min > max)
+ policy->min = max;
+ if (policy->max > max)
+ policy->max = max;
+ if (policy->min > policy->max)
+ policy->min = policy->max;
+}
+
+/**
+ * devfreq_verify_within_dev_limits() - Adjust a devfreq policy if needed to
+ * make sure its min/max values are within
+ * the frequency range supported by the
+ * device.
+ * @policy: the policy
+ */
+static inline void
+devfreq_verify_within_dev_limits(struct devfreq_policy *policy)
+{
+ devfreq_verify_within_limits(policy, policy->devinfo.min_freq,
+ policy->devinfo.max_freq);
+}
+
+struct devfreq *dev_to_devfreq(struct device *dev);
+
#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
/**
* struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
@@ -394,10 +443,26 @@ static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
return ERR_PTR(-ENODEV);
}

+static inline void devfreq_verify_within_limits(struct devfreq_policy *policy,
+ unsigned int min, unsigned int max)
+{
+}
+
+static inline void
+devfreq_verify_within_dev_limits(struct devfreq_policy *policy)
+{
+}
+
static inline int devfreq_update_stats(struct devfreq *df)
{
return -EINVAL;
}
+
+static inline struct devfreq *dev_to_devfreq(struct device *dev)
+{
+ return NULL;
+}
+
#endif /* CONFIG_PM_DEVFREQ */

#endif /* __LINUX_DEVFREQ_H__ */
--
2.18.0.203.gfac676dfb9-goog
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