--- /dev/null
+/*
+ * 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
Code Review / kvmfornfv.git / blobdiff