diff options
Diffstat (limited to 'drivers/base/power/opp.c')
| -rw-r--r-- | drivers/base/power/opp.c | 927 |
1 files changed, 927 insertions, 0 deletions
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c new file mode 100644 index 000000000..677fb2843 --- /dev/null +++ b/drivers/base/power/opp.c @@ -0,0 +1,927 @@ +/* + * Generic OPP Interface + * + * Copyright (C) 2009-2010 Texas Instruments Incorporated. + * Nishanth Menon + * Romit Dasgupta + * Kevin Hilman + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/device.h> +#include <linux/list.h> +#include <linux/rculist.h> +#include <linux/rcupdate.h> +#include <linux/pm_opp.h> +#include <linux/of.h> +#include <linux/export.h> + +/* + * Internal data structure organization with the OPP layer library is as + * follows: + * dev_opp_list (root) + * |- device 1 (represents voltage domain 1) + * | |- opp 1 (availability, freq, voltage) + * | |- opp 2 .. + * ... ... + * | `- opp n .. + * |- device 2 (represents the next voltage domain) + * ... + * `- device m (represents mth voltage domain) + * device 1, 2.. are represented by dev_opp structure while each opp + * is represented by the opp structure. + */ + +/** + * struct dev_pm_opp - Generic OPP description structure + * @node: opp list node. The nodes are maintained throughout the lifetime + * of boot. It is expected only an optimal set of OPPs are + * added to the library by the SoC framework. + * RCU usage: opp list is traversed with RCU locks. node + * modification is possible realtime, hence the modifications + * are protected by the dev_opp_list_lock for integrity. + * IMPORTANT: the opp nodes should be maintained in increasing + * order. + * @dynamic: not-created from static DT entries. + * @available: true/false - marks if this OPP as available or not + * @rate: Frequency in hertz + * @u_volt: Nominal voltage in microvolts corresponding to this OPP + * @dev_opp: points back to the device_opp struct this opp belongs to + * @rcu_head: RCU callback head used for deferred freeing + * + * This structure stores the OPP information for a given device. + */ +struct dev_pm_opp { + struct list_head node; + + bool available; + bool dynamic; + unsigned long rate; + unsigned long u_volt; + + struct device_opp *dev_opp; + struct rcu_head rcu_head; +}; + +/** + * struct device_opp - Device opp structure + * @node: list node - contains the devices with OPPs that + * have been registered. Nodes once added are not modified in this + * list. + * RCU usage: nodes are not modified in the list of device_opp, + * however addition is possible and is secured by dev_opp_list_lock + * @dev: device pointer + * @srcu_head: notifier head to notify the OPP availability changes. + * @rcu_head: RCU callback head used for deferred freeing + * @opp_list: list of opps + * + * This is an internal data structure maintaining the link to opps attached to + * a device. This structure is not meant to be shared to users as it is + * meant for book keeping and private to OPP library. + * + * Because the opp structures can be used from both rcu and srcu readers, we + * need to wait for the grace period of both of them before freeing any + * resources. And so we have used kfree_rcu() from within call_srcu() handlers. + */ +struct device_opp { + struct list_head node; + + struct device *dev; + struct srcu_notifier_head srcu_head; + struct rcu_head rcu_head; + struct list_head opp_list; +}; + +/* + * The root of the list of all devices. All device_opp structures branch off + * from here, with each device_opp containing the list of opp it supports in + * various states of availability. + */ +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 + * @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. + * + * 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) +{ + struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV); + + if (unlikely(IS_ERR_OR_NULL(dev))) { + pr_err("%s: Invalid parameters\n", __func__); + return ERR_PTR(-EINVAL); + } + + list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) { + if (tmp_dev_opp->dev == dev) { + dev_opp = tmp_dev_opp; + break; + } + } + + return dev_opp; +} + +/** + * 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 0 + * + * Locking: This function must be called under rcu_read_lock(). opp is a rcu + * protected pointer. This means that opp which could have been fetched by + * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are + * under RCU lock. The pointer returned by the opp_find_freq family must be + * used in the same section as the usage of this function with the pointer + * prior to unlocking with rcu_read_unlock() to maintain the integrity of the + * pointer. + */ +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__); + else + v = tmp_opp->u_volt; + + return v; +} +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 0 + * + * Locking: This function must be called under rcu_read_lock(). opp is a rcu + * protected pointer. This means that opp which could have been fetched by + * opp_find_freq_{exact,ceil,floor} functions is valid as long as we are + * under RCU lock. The pointer returned by the opp_find_freq family must be + * used in the same section as the usage of this function with the pointer + * prior to unlocking with rcu_read_unlock() to maintain the integrity of the + * pointer. + */ +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__); + else + f = tmp_opp->rate; + + return f; +} +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 + * + * 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(). + */ +int dev_pm_opp_get_opp_count(struct device *dev) +{ + struct device_opp *dev_opp; + struct dev_pm_opp *temp_opp; + int count = 0; + + rcu_read_lock(); + + dev_opp = _find_device_opp(dev); + if (IS_ERR(dev_opp)) { + 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) { + if (temp_opp->available) + count++; + } + +out_unlock: + rcu_read_unlock(); + return count; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count); + +/** + * dev_pm_opp_find_freq_exact() - search for an exact frequency + * @dev: device for which we do this operation + * @freq: frequency to search for + * @available: true/false - match for available opp + * + * 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 + * + * Note: available is a modifier for the search. if available=true, then the + * match is for exact matching frequency and is available in the stored OPP + * table. if false, the match is for exact frequency which is not available. + * + * This provides a mechanism to enable an opp which is not available currently + * or the opposite as well. + * + * Locking: This function must be called under rcu_read_lock(). 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 dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev, + unsigned long freq, + bool available) +{ + struct device_opp *dev_opp; + struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE); + + 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); + return ERR_PTR(r); + } + + list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { + if (temp_opp->available == available && + temp_opp->rate == freq) { + opp = temp_opp; + break; + } + } + + return opp; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact); + +/** + * dev_pm_opp_find_freq_ceil() - Search for an rounded ceil freq + * @dev: device for which we do this operation + * @freq: Start frequency + * + * Search for the matching ceil *available* OPP from a starting freq + * for a device. + * + * 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 + * ERANGE: no match found for search + * ENODEV: if device not found in list of registered devices + * + * Locking: This function must be called under rcu_read_lock(). 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 dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev, + unsigned long *freq) +{ + 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); + if (IS_ERR(dev_opp)) + return ERR_CAST(dev_opp); + + list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { + if (temp_opp->available && temp_opp->rate >= *freq) { + opp = temp_opp; + *freq = opp->rate; + break; + } + } + + return opp; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil); + +/** + * dev_pm_opp_find_freq_floor() - Search for a rounded floor freq + * @dev: device for which we do this operation + * @freq: Start frequency + * + * Search for the matching floor *available* OPP from a starting freq + * for a device. + * + * 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 + * ERANGE: no match found for search + * ENODEV: if device not found in list of registered devices + * + * Locking: This function must be called under rcu_read_lock(). 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 dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev, + unsigned long *freq) +{ + 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); + if (IS_ERR(dev_opp)) + return ERR_CAST(dev_opp); + + list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) { + if (temp_opp->available) { + /* go to the next node, before choosing prev */ + if (temp_opp->rate > *freq) + break; + else + opp = temp_opp; + } + } + if (!IS_ERR(opp)) + *freq = opp->rate; + + return opp; +} +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; + + /* + * Allocate a new device OPP table. In the infrequent case where a new + * device is needed to be added, we pay this penalty. + */ + dev_opp = kzalloc(sizeof(*dev_opp), GFP_KERNEL); + if (!dev_opp) + return NULL; + + dev_opp->dev = dev; + srcu_init_notifier_head(&dev_opp->srcu_head); + INIT_LIST_HEAD(&dev_opp->opp_list); + + /* Secure the device list modification */ + list_add_rcu(&dev_opp->node, &dev_opp_list); + 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) +{ + struct device_opp *dev_opp = NULL; + struct dev_pm_opp *opp, *new_opp; + struct list_head *head; + int ret; + + /* allocate new OPP node */ + new_opp = kzalloc(sizeof(*new_opp), GFP_KERNEL); + if (!new_opp) + return -ENOMEM; + + /* Hold our list modification lock here */ + mutex_lock(&dev_opp_list_lock); + + /* populate the opp table */ + new_opp->rate = freq; + new_opp->u_volt = u_volt; + new_opp->available = true; + new_opp->dynamic = dynamic; + + /* Check for existing list for 'dev' */ + dev_opp = _find_device_opp(dev); + if (IS_ERR(dev_opp)) { + dev_opp = _add_device_opp(dev); + if (!dev_opp) { + ret = -ENOMEM; + goto free_opp; + } + + head = &dev_opp->opp_list; + goto list_add; + } + + /* + * Insert new OPP in order of increasing frequency + * and discard if already present + */ + head = &dev_opp->opp_list; + list_for_each_entry_rcu(opp, &dev_opp->opp_list, node) { + if (new_opp->rate <= opp->rate) + break; + else + head = &opp->node; + } + + /* Duplicate OPPs ? */ + if (new_opp->rate == opp->rate) { + ret = opp->available && new_opp->u_volt == opp->u_volt ? + 0 : -EEXIST; + + dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n", + __func__, opp->rate, opp->u_volt, opp->available, + new_opp->rate, new_opp->u_volt, new_opp->available); + goto free_opp; + } + +list_add: + new_opp->dev_opp = dev_opp; + list_add_rcu(&new_opp->node, head); + mutex_unlock(&dev_opp_list_lock); + + /* + * Notify the changes in the availability of the operable + * frequency/voltage list. + */ + srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADD, new_opp); + return 0; + +free_opp: + mutex_unlock(&dev_opp_list_lock); + kfree(new_opp); + return ret; +} + +/** + * dev_pm_opp_add() - Add an OPP table from a table definitions + * @dev: device for which we do this operation + * @freq: Frequency in Hz for this OPP + * @u_volt: Voltage in uVolts for this OPP + * + * 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. + * + * 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 + */ +int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt) +{ + return _opp_add_dynamic(dev, freq, u_volt, true); +} +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); + + 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); + + 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) +{ + /* + * Notify the changes in the availability of the operable + * frequency/voltage list. + */ + 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); + + 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); + } +} + +/** + * dev_pm_opp_remove() - Remove an OPP from OPP list + * @dev: device for which we do this operation + * @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) +{ + struct dev_pm_opp *opp; + struct device_opp *dev_opp; + bool found = false; + + /* Hold our list modification lock here */ + mutex_lock(&dev_opp_list_lock); + + dev_opp = _find_device_opp(dev); + if (IS_ERR(dev_opp)) + goto unlock; + + list_for_each_entry(opp, &dev_opp->opp_list, node) { + if (opp->rate == freq) { + found = true; + break; + } + } + + if (!found) { + dev_warn(dev, "%s: Couldn't find OPP with freq: %lu\n", + __func__, freq); + goto unlock; + } + + _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 + * @dev: device for which we do this operation + * @freq: OPP frequency to modify availability + * @availability_req: availability status requested for this opp + * + * Set the availability of an OPP with an RCU operation, opp_{enable,disable} + * share a common logic which is isolated here. + * + * 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. + * + * 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 locking or synchronize_rcu() blocking calls cannot be used. + */ +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); + int r = 0; + + /* keep the node allocated */ + new_opp = kmalloc(sizeof(*new_opp), GFP_KERNEL); + if (!new_opp) + return -ENOMEM; + + mutex_lock(&dev_opp_list_lock); + + /* Find the device_opp */ + 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); + goto unlock; + } + + /* Do we have the frequency? */ + list_for_each_entry(tmp_opp, &dev_opp->opp_list, node) { + if (tmp_opp->rate == freq) { + opp = tmp_opp; + break; + } + } + if (IS_ERR(opp)) { + r = PTR_ERR(opp); + goto unlock; + } + + /* Is update really needed? */ + if (opp->available == availability_req) + goto unlock; + /* copy the old data over */ + *new_opp = *opp; + + /* plug in new node */ + new_opp->available = availability_req; + + 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); + + /* Notify the change of the OPP availability */ + if (availability_req) + srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ENABLE, + new_opp); + else + srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_DISABLE, + new_opp); + + return 0; + +unlock: + mutex_unlock(&dev_opp_list_lock); + kfree(new_opp); + return r; +} + +/** + * dev_pm_opp_enable() - Enable a specific OPP + * @dev: device for which we do this operation + * @freq: OPP frequency to enable + * + * Enables a provided opp. If the operation is valid, this returns 0, else the + * corresponding error value. It is meant to be used for users an OPP available + * after being temporarily made unavailable with dev_pm_opp_disable. + * + * Locking: The internal device_opp and opp structures are RCU protected. + * Hence this function indirectly uses RCU and 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 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); +} +EXPORT_SYMBOL_GPL(dev_pm_opp_enable); + +/** + * dev_pm_opp_disable() - Disable a specific OPP + * @dev: device for which we do this operation + * @freq: OPP frequency to disable + * + * Disables a provided opp. If the operation is valid, this returns + * 0, else the corresponding error value. It is meant to be a temporary + * control by users to make this OPP not available until the circumstances are + * right to make it available again (with a call to dev_pm_opp_enable). + * + * Locking: The internal device_opp and opp structures are RCU protected. + * Hence this function indirectly uses RCU and 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 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); +} +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); + + 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 +/** + * of_init_opp_table() - Initialize opp table from device tree + * @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) +{ + const struct property *prop; + const __be32 *val; + int nr; + + prop = of_find_property(dev->of_node, "operating-points", NULL); + if (!prop) + return -ENODEV; + if (!prop->value) + return -ENODATA; + + /* + * Each OPP is a set of tuples consisting of frequency and + * voltage like <freq-kHz vol-uV>. + */ + nr = prop->length / sizeof(u32); + if (nr % 2) { + dev_err(dev, "%s: Invalid OPP list\n", __func__); + return -EINVAL; + } + + val = prop->value; + while (nr) { + unsigned long freq = be32_to_cpup(val++) * 1000; + unsigned long volt = be32_to_cpup(val++); + + if (_opp_add_dynamic(dev, freq, volt, false)) + dev_warn(dev, "%s: Failed to add OPP %ld\n", + __func__, freq); + nr -= 2; + } + + return 0; +} +EXPORT_SYMBOL_GPL(of_init_opp_table); + +/** + * of_free_opp_table() - Free OPP table entries created from static DT entries + * @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) +{ + struct device_opp *dev_opp; + struct dev_pm_opp *opp, *tmp; + + /* Check for existing list for 'dev' */ + 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); + + /* Free static OPPs */ + list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) { + if (!opp->dynamic) + _opp_remove(dev_opp, opp); + } + + mutex_unlock(&dev_opp_list_lock); +} +EXPORT_SYMBOL_GPL(of_free_opp_table); +#endif |