From 984f16c8490cba715444124a453ed4a2ac7a5a54 Mon Sep 17 00:00:00 2001 From: Nishanth Menon Date: Wed, 24 Dec 2014 11:22:57 -0600 Subject: [PATCH] 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: Nishanth Menon Signed-off-by: Rafael J. Wysocki --- drivers/base/power/opp.c | 127 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 114 insertions(+), 13 deletions(-) diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c index f4aa85a..1d20e09 100644 --- a/drivers/base/power/opp.c +++ b/drivers/base/power/opp.c @@ -123,7 +123,7 @@ do { \ * Search list of device OPPs for one containing matching device. Does a RCU * 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. * * 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) * dev_pm_opp_get_voltage() - Gets the voltage corresponding to an available opp * @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 * * 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); * dev_pm_opp_get_freq() - Gets the frequency corresponding to an available opp * @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 * * 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); * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list * @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. * * Locking: This function takes rcu_read_lock(). @@ -251,9 +251,9 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count); * @freq: frequency to search for * @available: true/false - match for available opp * - * Searches for exact match in the opp list and returns pointer to the matching - * opp if found, else returns ERR_PTR in case of error and should be handled - * using IS_ERR. Error return values can be: + * Return: Searches for exact match in the opp list and returns pointer to the + * matching opp if found, else returns ERR_PTR in case of error and should + * be handled using IS_ERR. Error return values can be: * EINVAL: for bad pointer * ERANGE: no match found for search * ENODEV: if device not found in list of registered devices @@ -307,7 +307,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact); * Search for the matching ceil *available* OPP from a starting freq * 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 * values can be: * EINVAL: for bad pointer @@ -357,7 +357,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil); * Search for the matching floor *available* OPP from a starting freq * 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 * values can be: * EINVAL: for bad pointer @@ -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); +/** + * _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) { struct device_opp *dev_opp; @@ -424,6 +433,33 @@ static struct device_opp *_add_device_opp(struct device *dev) 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, long u_volt, bool dynamic) { @@ -519,11 +555,11 @@ free_opp: * mutex cannot be locked. * * Return: - * 0: On success OR + * 0 On success OR * 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 - * -ENOMEM: Memory allocation failure + * -ENOMEM Memory allocation failure */ 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); +/** + * _kfree_opp_rcu() - Free OPP RCU handler + * @head: RCU head + */ static void _kfree_opp_rcu(struct rcu_head *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) 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) { 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) 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, struct dev_pm_opp *opp) { @@ -569,6 +624,12 @@ static void _opp_remove(struct device_opp *dev_opp, * @freq: OPP to remove with matching 'freq' * * 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) { @@ -611,7 +672,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove); * Set the availability of an OPP with an RCU operation, opp_{enable,disable} * 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 * successful. * @@ -700,6 +761,10 @@ unlock: * integrity of the internal data structures. Callers should ensure that * this function is *NOT* called under RCU protection or in contexts where * 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) { @@ -722,6 +787,10 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_enable); * integrity of the internal data structures. Callers should ensure that * this function is *NOT* called under RCU protection or in contexts where * 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) { @@ -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: 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) { @@ -750,6 +829,22 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_notifier); * @dev: device pointer used to lookup device OPPs. * * 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) { @@ -793,6 +888,12 @@ EXPORT_SYMBOL_GPL(of_init_opp_table); * @dev: device pointer used to lookup device OPPs. * * 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) { -- 2.7.4