Commit 984f16c8 authored by Nishanth Menon's avatar Nishanth Menon Committed by Rafael J. Wysocki

PM / OPP: Update kernel documentation

kernel doc has gotten bit-rotted over time. Re-sync with Locking and
Return information. document all functions properly and ensure that
./scripts/kernel-doc -v  ./drivers/base/power/opp.c >/dev/null returns
no errors
Signed-off-by: default avatarNishanth Menon <nm@ti.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 327854c8
...@@ -123,7 +123,7 @@ do { \ ...@@ -123,7 +123,7 @@ do { \
* Search list of device OPPs for one containing matching device. Does a RCU * Search list of device OPPs for one containing matching device. Does a RCU
* reader operation to grab the pointer needed. * reader operation to grab the pointer needed.
* *
* Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or * Return: pointer to 'struct device_opp' if found, otherwise -ENODEV or
* -EINVAL based on type of error. * -EINVAL based on type of error.
* *
* Locking: This function must be called under rcu_read_lock(). device_opp * Locking: This function must be called under rcu_read_lock(). device_opp
...@@ -153,7 +153,7 @@ static struct device_opp *_find_device_opp(struct device *dev) ...@@ -153,7 +153,7 @@ static struct device_opp *_find_device_opp(struct device *dev)
* dev_pm_opp_get_voltage() - Gets the voltage corresponding to an available opp * dev_pm_opp_get_voltage() - Gets the voltage corresponding to an available opp
* @opp: opp for which voltage has to be returned for * @opp: opp for which voltage has to be returned for
* *
* Return voltage in micro volt corresponding to the opp, else * Return: voltage in micro volt corresponding to the opp, else
* return 0 * return 0
* *
* Locking: This function must be called under rcu_read_lock(). opp is a rcu * Locking: This function must be called under rcu_read_lock(). opp is a rcu
...@@ -183,7 +183,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_voltage); ...@@ -183,7 +183,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_voltage);
* dev_pm_opp_get_freq() - Gets the frequency corresponding to an available opp * dev_pm_opp_get_freq() - Gets the frequency corresponding to an available opp
* @opp: opp for which frequency has to be returned for * @opp: opp for which frequency has to be returned for
* *
* Return frequency in hertz corresponding to the opp, else * Return: frequency in hertz corresponding to the opp, else
* return 0 * return 0
* *
* Locking: This function must be called under rcu_read_lock(). opp is a rcu * Locking: This function must be called under rcu_read_lock(). opp is a rcu
...@@ -213,7 +213,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq); ...@@ -213,7 +213,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
* dev_pm_opp_get_opp_count() - Get number of opps available in the opp list * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
* @dev: device for which we do this operation * @dev: device for which we do this operation
* *
* This function returns the number of available opps if there are any, * Return: This function returns the number of available opps if there are any,
* else returns 0 if none or the corresponding error value. * else returns 0 if none or the corresponding error value.
* *
* Locking: This function takes rcu_read_lock(). * Locking: This function takes rcu_read_lock().
...@@ -251,9 +251,9 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count); ...@@ -251,9 +251,9 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);
* @freq: frequency to search for * @freq: frequency to search for
* @available: true/false - match for available opp * @available: true/false - match for available opp
* *
* Searches for exact match in the opp list and returns pointer to the matching * Return: Searches for exact match in the opp list and returns pointer to the
* opp if found, else returns ERR_PTR in case of error and should be handled * matching opp if found, else returns ERR_PTR in case of error and should
* using IS_ERR. Error return values can be: * be handled using IS_ERR. Error return values can be:
* EINVAL: for bad pointer * EINVAL: for bad pointer
* ERANGE: no match found for search * ERANGE: no match found for search
* ENODEV: if device not found in list of registered devices * ENODEV: if device not found in list of registered devices
...@@ -307,7 +307,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact); ...@@ -307,7 +307,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact);
* Search for the matching ceil *available* OPP from a starting freq * Search for the matching ceil *available* OPP from a starting freq
* for a device. * for a device.
* *
* Returns matching *opp and refreshes *freq accordingly, else returns * Return: matching *opp and refreshes *freq accordingly, else returns
* ERR_PTR in case of error and should be handled using IS_ERR. Error return * ERR_PTR in case of error and should be handled using IS_ERR. Error return
* values can be: * values can be:
* EINVAL: for bad pointer * EINVAL: for bad pointer
...@@ -357,7 +357,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil); ...@@ -357,7 +357,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil);
* Search for the matching floor *available* OPP from a starting freq * Search for the matching floor *available* OPP from a starting freq
* for a device. * for a device.
* *
* Returns matching *opp and refreshes *freq accordingly, else returns * Return: matching *opp and refreshes *freq accordingly, else returns
* ERR_PTR in case of error and should be handled using IS_ERR. Error return * ERR_PTR in case of error and should be handled using IS_ERR. Error return
* values can be: * values can be:
* EINVAL: for bad pointer * EINVAL: for bad pointer
...@@ -403,6 +403,15 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, ...@@ -403,6 +403,15 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
} }
EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor); EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
/**
* _add_device_opp() - Allocate a new device OPP table
* @dev: device for which we do this operation
*
* New device node which uses OPPs - used when multiple devices with OPP tables
* are maintained.
*
* Return: valid device_opp pointer if success, else NULL.
*/
static struct device_opp *_add_device_opp(struct device *dev) static struct device_opp *_add_device_opp(struct device *dev)
{ {
struct device_opp *dev_opp; struct device_opp *dev_opp;
...@@ -424,6 +433,33 @@ static struct device_opp *_add_device_opp(struct device *dev) ...@@ -424,6 +433,33 @@ static struct device_opp *_add_device_opp(struct device *dev)
return dev_opp; return dev_opp;
} }
/**
* _opp_add_dynamic() - Allocate a dynamic OPP.
* @dev: device for which we do this operation
* @freq: Frequency in Hz for this OPP
* @u_volt: Voltage in uVolts for this OPP
* @dynamic: Dynamically added OPPs.
*
* This function adds an opp definition to the opp list and returns status.
* The opp is made available by default and it can be controlled using
* dev_pm_opp_enable/disable functions and may be removed by dev_pm_opp_remove.
*
* NOTE: "dynamic" parameter impacts OPPs added by the of_init_opp_table and
* freed by of_free_opp_table.
*
* Locking: The internal device_opp and opp structures are RCU protected.
* Hence this function internally uses RCU updater strategy with mutex locks
* to keep the integrity of the internal data structures. Callers should ensure
* that this function is *NOT* called under RCU protection or in contexts where
* mutex cannot be locked.
*
* Return:
* 0 On success OR
* Duplicate OPPs (both freq and volt are same) and opp->available
* -EEXIST Freq are same and volt are different OR
* Duplicate OPPs (both freq and volt are same) and !opp->available
* -ENOMEM Memory allocation failure
*/
static int _opp_add_dynamic(struct device *dev, unsigned long freq, static int _opp_add_dynamic(struct device *dev, unsigned long freq,
long u_volt, bool dynamic) long u_volt, bool dynamic)
{ {
...@@ -519,11 +555,11 @@ static int _opp_add_dynamic(struct device *dev, unsigned long freq, ...@@ -519,11 +555,11 @@ static int _opp_add_dynamic(struct device *dev, unsigned long freq,
* mutex cannot be locked. * mutex cannot be locked.
* *
* Return: * Return:
* 0: On success OR * 0 On success OR
* Duplicate OPPs (both freq and volt are same) and opp->available * Duplicate OPPs (both freq and volt are same) and opp->available
* -EEXIST: Freq are same and volt are different OR * -EEXIST Freq are same and volt are different OR
* Duplicate OPPs (both freq and volt are same) and !opp->available * Duplicate OPPs (both freq and volt are same) and !opp->available
* -ENOMEM: Memory allocation failure * -ENOMEM Memory allocation failure
*/ */
int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
{ {
...@@ -531,6 +567,10 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) ...@@ -531,6 +567,10 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
} }
EXPORT_SYMBOL_GPL(dev_pm_opp_add); EXPORT_SYMBOL_GPL(dev_pm_opp_add);
/**
* _kfree_opp_rcu() - Free OPP RCU handler
* @head: RCU head
*/
static void _kfree_opp_rcu(struct rcu_head *head) static void _kfree_opp_rcu(struct rcu_head *head)
{ {
struct dev_pm_opp *opp = container_of(head, struct dev_pm_opp, rcu_head); struct dev_pm_opp *opp = container_of(head, struct dev_pm_opp, rcu_head);
...@@ -538,6 +578,10 @@ static void _kfree_opp_rcu(struct rcu_head *head) ...@@ -538,6 +578,10 @@ static void _kfree_opp_rcu(struct rcu_head *head)
kfree_rcu(opp, rcu_head); kfree_rcu(opp, rcu_head);
} }
/**
* _kfree_device_rcu() - Free device_opp RCU handler
* @head: RCU head
*/
static void _kfree_device_rcu(struct rcu_head *head) static void _kfree_device_rcu(struct rcu_head *head)
{ {
struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head); struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head);
...@@ -545,6 +589,17 @@ static void _kfree_device_rcu(struct rcu_head *head) ...@@ -545,6 +589,17 @@ static void _kfree_device_rcu(struct rcu_head *head)
kfree_rcu(device_opp, rcu_head); kfree_rcu(device_opp, rcu_head);
} }
/**
* _opp_remove() - Remove an OPP from a table definition
* @dev_opp: points back to the device_opp struct this opp belongs to
* @opp: pointer to the OPP to remove
*
* This function removes an opp definition from the opp list.
*
* Locking: The internal device_opp and opp structures are RCU protected.
* It is assumed that the caller holds required mutex for an RCU updater
* strategy.
*/
static void _opp_remove(struct device_opp *dev_opp, static void _opp_remove(struct device_opp *dev_opp,
struct dev_pm_opp *opp) struct dev_pm_opp *opp)
{ {
...@@ -569,6 +624,12 @@ static void _opp_remove(struct device_opp *dev_opp, ...@@ -569,6 +624,12 @@ static void _opp_remove(struct device_opp *dev_opp,
* @freq: OPP to remove with matching 'freq' * @freq: OPP to remove with matching 'freq'
* *
* This function removes an opp from the opp list. * This function removes an opp from the opp list.
*
* Locking: The internal device_opp and opp structures are RCU protected.
* Hence this function internally uses RCU updater strategy with mutex locks
* to keep the integrity of the internal data structures. Callers should ensure
* that this function is *NOT* called under RCU protection or in contexts where
* mutex cannot be locked.
*/ */
void dev_pm_opp_remove(struct device *dev, unsigned long freq) void dev_pm_opp_remove(struct device *dev, unsigned long freq)
{ {
...@@ -611,7 +672,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove); ...@@ -611,7 +672,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
* Set the availability of an OPP with an RCU operation, opp_{enable,disable} * Set the availability of an OPP with an RCU operation, opp_{enable,disable}
* share a common logic which is isolated here. * share a common logic which is isolated here.
* *
* Returns -EINVAL for bad pointers, -ENOMEM if no memory available for the * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
* copy operation, returns 0 if no modifcation was done OR modification was * copy operation, returns 0 if no modifcation was done OR modification was
* successful. * successful.
* *
...@@ -700,6 +761,10 @@ static int _opp_set_availability(struct device *dev, unsigned long freq, ...@@ -700,6 +761,10 @@ static int _opp_set_availability(struct device *dev, unsigned long freq,
* integrity of the internal data structures. Callers should ensure that * integrity of the internal data structures. Callers should ensure that
* this function is *NOT* called under RCU protection or in contexts where * this function is *NOT* called under RCU protection or in contexts where
* mutex locking or synchronize_rcu() blocking calls cannot be used. * mutex locking or synchronize_rcu() blocking calls cannot be used.
*
* Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
* copy operation, returns 0 if no modifcation was done OR modification was
* successful.
*/ */
int dev_pm_opp_enable(struct device *dev, unsigned long freq) int dev_pm_opp_enable(struct device *dev, unsigned long freq)
{ {
...@@ -722,6 +787,10 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_enable); ...@@ -722,6 +787,10 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_enable);
* integrity of the internal data structures. Callers should ensure that * integrity of the internal data structures. Callers should ensure that
* this function is *NOT* called under RCU protection or in contexts where * this function is *NOT* called under RCU protection or in contexts where
* mutex locking or synchronize_rcu() blocking calls cannot be used. * mutex locking or synchronize_rcu() blocking calls cannot be used.
*
* Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
* copy operation, returns 0 if no modifcation was done OR modification was
* successful.
*/ */
int dev_pm_opp_disable(struct device *dev, unsigned long freq) int dev_pm_opp_disable(struct device *dev, unsigned long freq)
{ {
...@@ -732,6 +801,16 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_disable); ...@@ -732,6 +801,16 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
/** /**
* dev_pm_opp_get_notifier() - find notifier_head of the device with opp * dev_pm_opp_get_notifier() - find notifier_head of the device with opp
* @dev: device pointer used to lookup device OPPs. * @dev: device pointer used to lookup device OPPs.
*
* Return: pointer to notifier head if found, otherwise -ENODEV or
* -EINVAL based on type of error casted as pointer. value must be checked
* with IS_ERR to determine valid pointer or error result.
*
* Locking: This function must be called under rcu_read_lock(). dev_opp is a RCU
* protected pointer. The reason for the same is that the opp pointer which is
* returned will remain valid for use with opp_get_{voltage, freq} only while
* under the locked area. The pointer returned must be used prior to unlocking
* with rcu_read_unlock() to maintain the integrity of the pointer.
*/ */
struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev) struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev)
{ {
...@@ -750,6 +829,22 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_notifier); ...@@ -750,6 +829,22 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_notifier);
* @dev: device pointer used to lookup device OPPs. * @dev: device pointer used to lookup device OPPs.
* *
* Register the initial OPP table with the OPP library for given device. * Register the initial OPP table with the OPP library for given device.
*
* Locking: The internal device_opp and opp structures are RCU protected.
* Hence this function indirectly uses RCU updater strategy with mutex locks
* to keep the integrity of the internal data structures. Callers should ensure
* that this function is *NOT* called under RCU protection or in contexts where
* mutex cannot be locked.
*
* Return:
* 0 On success OR
* Duplicate OPPs (both freq and volt are same) and opp->available
* -EEXIST Freq are same and volt are different OR
* Duplicate OPPs (both freq and volt are same) and !opp->available
* -ENOMEM Memory allocation failure
* -ENODEV when 'operating-points' property is not found or is invalid data
* in device node.
* -ENODATA when empty 'operating-points' property is found
*/ */
int of_init_opp_table(struct device *dev) int of_init_opp_table(struct device *dev)
{ {
...@@ -793,6 +888,12 @@ EXPORT_SYMBOL_GPL(of_init_opp_table); ...@@ -793,6 +888,12 @@ EXPORT_SYMBOL_GPL(of_init_opp_table);
* @dev: device pointer used to lookup device OPPs. * @dev: device pointer used to lookup device OPPs.
* *
* Free OPPs created using static entries present in DT. * Free OPPs created using static entries present in DT.
*
* Locking: The internal device_opp and opp structures are RCU protected.
* Hence this function indirectly uses RCU updater strategy with mutex locks
* to keep the integrity of the internal data structures. Callers should ensure
* that this function is *NOT* called under RCU protection or in contexts where
* mutex cannot be locked.
*/ */
void of_free_opp_table(struct device *dev) void of_free_opp_table(struct device *dev)
{ {
......
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