diff options
Diffstat (limited to 'drivers/base/power/opp.c')
| -rw-r--r-- | drivers/base/power/opp.c | 233 |
1 files changed, 181 insertions, 52 deletions
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c index d24dd614a0bd..15bf29974c31 100644 --- a/drivers/base/power/opp.c +++ b/drivers/base/power/opp.c @@ -108,21 +108,29 @@ static LIST_HEAD(dev_opp_list); /* Lock to allow exclusive modification to the device and opp lists */ static DEFINE_MUTEX(dev_opp_list_lock); +#define opp_rcu_lockdep_assert() \ +do { \ + rcu_lockdep_assert(rcu_read_lock_held() || \ + lockdep_is_held(&dev_opp_list_lock), \ + "Missing rcu_read_lock() or " \ + "dev_opp_list_lock protection"); \ +} while (0) + /** - * find_device_opp() - find device_opp struct using device pointer + * _find_device_opp() - find device_opp struct using device pointer * @dev: device pointer used to lookup device OPPs * * 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 * is a RCU protected pointer. This means that device_opp is valid as long * as we are under RCU lock. */ -static struct device_opp *find_device_opp(struct device *dev) +static struct device_opp *_find_device_opp(struct device *dev) { struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV); @@ -145,7 +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 @@ -161,6 +169,8 @@ unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp) struct dev_pm_opp *tmp_opp; unsigned long v = 0; + opp_rcu_lockdep_assert(); + tmp_opp = rcu_dereference(opp); if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) pr_err("%s: Invalid parameters\n", __func__); @@ -175,7 +185,7 @@ 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 @@ -191,6 +201,8 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp) struct dev_pm_opp *tmp_opp; unsigned long f = 0; + opp_rcu_lockdep_assert(); + tmp_opp = rcu_dereference(opp); if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available) pr_err("%s: Invalid parameters\n", __func__); @@ -205,12 +217,10 @@ 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 must be called under rcu_read_lock(). This function - * internally references two RCU protected structures: device_opp and opp which - * are safe as long as we are under a common RCU locked section. + * Locking: This function takes rcu_read_lock(). */ int dev_pm_opp_get_opp_count(struct device *dev) { @@ -218,11 +228,14 @@ int dev_pm_opp_get_opp_count(struct device *dev) struct dev_pm_opp *temp_opp; int count = 0; - dev_opp = find_device_opp(dev); + rcu_read_lock(); + + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) { - int r = PTR_ERR(dev_opp); - dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); - return r; + count = PTR_ERR(dev_opp); + dev_err(dev, "%s: device OPP not found (%d)\n", + __func__, count); + goto out_unlock; } list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { @@ -230,6 +243,8 @@ int dev_pm_opp_get_opp_count(struct device *dev) count++; } +out_unlock: + rcu_read_unlock(); return count; } EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count); @@ -240,9 +255,9 @@ 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 @@ -267,7 +282,9 @@ struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev, struct device_opp *dev_opp; struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); - dev_opp = find_device_opp(dev); + opp_rcu_lockdep_assert(); + + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) { int r = PTR_ERR(dev_opp); dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r); @@ -294,7 +311,7 @@ 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 @@ -313,12 +330,14 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev, struct device_opp *dev_opp; struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); + opp_rcu_lockdep_assert(); + if (!dev || !freq) { dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); return ERR_PTR(-EINVAL); } - dev_opp = find_device_opp(dev); + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) return ERR_CAST(dev_opp); @@ -342,7 +361,7 @@ 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 @@ -361,12 +380,14 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, struct device_opp *dev_opp; struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); + opp_rcu_lockdep_assert(); + if (!dev || !freq) { dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq); return ERR_PTR(-EINVAL); } - dev_opp = find_device_opp(dev); + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) return ERR_CAST(dev_opp); @@ -386,7 +407,16 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, } EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor); -static struct device_opp *add_device_opp(struct device *dev) +/** + * _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; @@ -407,8 +437,35 @@ static struct device_opp *add_device_opp(struct device *dev) return dev_opp; } -static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq, - unsigned long u_volt, bool dynamic) +/** + * _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) { struct device_opp *dev_opp = NULL; struct dev_pm_opp *opp, *new_opp; @@ -432,9 +489,9 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq, new_opp->dynamic = dynamic; /* Check for existing list for 'dev' */ - dev_opp = find_device_opp(dev); + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) { - dev_opp = add_device_opp(dev); + dev_opp = _add_device_opp(dev); if (!dev_opp) { ret = -ENOMEM; goto free_opp; @@ -502,34 +559,53 @@ 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) { - return dev_pm_opp_add_dynamic(dev, freq, u_volt, true); + return _opp_add_dynamic(dev, freq, u_volt, true); } EXPORT_SYMBOL_GPL(dev_pm_opp_add); -static void kfree_opp_rcu(struct rcu_head *head) +/** + * _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); kfree_rcu(opp, rcu_head); } -static void kfree_device_rcu(struct rcu_head *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); kfree_rcu(device_opp, rcu_head); } -static void __dev_pm_opp_remove(struct device_opp *dev_opp, - struct dev_pm_opp *opp) +/** + * _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) { /* * Notify the changes in the availability of the operable @@ -537,12 +613,12 @@ static void __dev_pm_opp_remove(struct device_opp *dev_opp, */ srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_REMOVE, opp); list_del_rcu(&opp->node); - call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, kfree_opp_rcu); + call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu); if (list_empty(&dev_opp->opp_list)) { list_del_rcu(&dev_opp->node); call_srcu(&dev_opp->srcu_head.srcu, &dev_opp->rcu_head, - kfree_device_rcu); + _kfree_device_rcu); } } @@ -552,6 +628,12 @@ static void __dev_pm_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) { @@ -562,7 +644,7 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq) /* Hold our list modification lock here */ mutex_lock(&dev_opp_list_lock); - dev_opp = find_device_opp(dev); + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) goto unlock; @@ -579,14 +661,14 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq) goto unlock; } - __dev_pm_opp_remove(dev_opp, opp); + _opp_remove(dev_opp, opp); unlock: mutex_unlock(&dev_opp_list_lock); } EXPORT_SYMBOL_GPL(dev_pm_opp_remove); /** - * opp_set_availability() - helper to set the availability of an opp + * _opp_set_availability() - helper to set the availability of an opp * @dev: device for which we do this operation * @freq: OPP frequency to modify availability * @availability_req: availability status requested for this opp @@ -594,7 +676,7 @@ 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. * @@ -604,8 +686,8 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove); * that this function is *NOT* called under RCU protection or in contexts where * mutex locking or synchronize_rcu() blocking calls cannot be used. */ -static int opp_set_availability(struct device *dev, unsigned long freq, - bool availability_req) +static int _opp_set_availability(struct device *dev, unsigned long freq, + bool availability_req) { struct device_opp *dev_opp; struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV); @@ -621,7 +703,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq, mutex_lock(&dev_opp_list_lock); /* Find the device_opp */ - dev_opp = find_device_opp(dev); + dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) { r = PTR_ERR(dev_opp); dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r); @@ -651,7 +733,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq, list_replace_rcu(&opp->node, &new_opp->node); mutex_unlock(&dev_opp_list_lock); - call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, kfree_opp_rcu); + call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu); /* Notify the change of the OPP availability */ if (availability_req) @@ -683,10 +765,14 @@ 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) { - return opp_set_availability(dev, freq, true); + return _opp_set_availability(dev, freq, true); } EXPORT_SYMBOL_GPL(dev_pm_opp_enable); @@ -705,26 +791,41 @@ 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) { - return opp_set_availability(dev, freq, false); + return _opp_set_availability(dev, freq, false); } 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) { - struct device_opp *dev_opp = find_device_opp(dev); + struct device_opp *dev_opp = _find_device_opp(dev); if (IS_ERR(dev_opp)) return ERR_CAST(dev_opp); /* matching type */ return &dev_opp->srcu_head; } +EXPORT_SYMBOL_GPL(dev_pm_opp_get_notifier); #ifdef CONFIG_OF /** @@ -732,6 +833,22 @@ struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev) * @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) { @@ -760,7 +877,7 @@ int of_init_opp_table(struct device *dev) unsigned long freq = be32_to_cpup(val++) * 1000; unsigned long volt = be32_to_cpup(val++); - if (dev_pm_opp_add_dynamic(dev, freq, volt, false)) + if (_opp_add_dynamic(dev, freq, volt, false)) dev_warn(dev, "%s: Failed to add OPP %ld\n", __func__, freq); nr -= 2; @@ -775,6 +892,12 @@ 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) { @@ -782,10 +905,16 @@ void of_free_opp_table(struct device *dev) struct dev_pm_opp *opp, *tmp; /* Check for existing list for 'dev' */ - dev_opp = find_device_opp(dev); - if (WARN(IS_ERR(dev_opp), "%s: dev_opp: %ld\n", dev_name(dev), - PTR_ERR(dev_opp))) + dev_opp = _find_device_opp(dev); + if (IS_ERR(dev_opp)) { + int error = PTR_ERR(dev_opp); + if (error != -ENODEV) + WARN(1, "%s: dev_opp: %d\n", + IS_ERR_OR_NULL(dev) ? + "Invalid device" : dev_name(dev), + error); return; + } /* Hold our list modification lock here */ mutex_lock(&dev_opp_list_lock); @@ -793,7 +922,7 @@ void of_free_opp_table(struct device *dev) /* Free static OPPs */ list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) { if (!opp->dynamic) - __dev_pm_opp_remove(dev_opp, opp); + _opp_remove(dev_opp, opp); } mutex_unlock(&dev_opp_list_lock); |