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diff --git a/drivers/base/power/opp/opp.h b/drivers/base/power/opp/opp.h
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+/*
+ * 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.
+ */
+
+#ifndef __DRIVER_OPP_H__
+#define __DRIVER_OPP_H__
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/pm_opp.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+
+/* Lock to allow exclusive modification to the device and opp lists */
+extern struct mutex dev_opp_list_lock;
+
+/*
+ * 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
+ * @turbo: true if turbo (boost) OPP
+ * @rate: Frequency in hertz
+ * @u_volt: Target voltage in microvolts corresponding to this OPP
+ * @u_volt_min: Minimum voltage in microvolts corresponding to this OPP
+ * @u_volt_max: Maximum voltage in microvolts corresponding to this OPP
+ * @u_amp: Maximum current drawn by the device in microamperes
+ * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
+ * frequency from any other OPP's frequency.
+ * @dev_opp: points back to the device_opp struct this opp belongs to
+ * @rcu_head: RCU callback head used for deferred freeing
+ * @np: OPP's device node.
+ *
+ * This structure stores the OPP information for a given device.
+ */
+struct dev_pm_opp {
+ struct list_head node;
+
+ bool available;
+ bool dynamic;
+ bool turbo;
+ unsigned long rate;
+
+ unsigned long u_volt;
+ unsigned long u_volt_min;
+ unsigned long u_volt_max;
+ unsigned long u_amp;
+ unsigned long clock_latency_ns;
+
+ struct device_opp *dev_opp;
+ struct rcu_head rcu_head;
+
+ struct device_node *np;
+};
+
+/**
+ * struct device_list_opp - devices managed by 'struct device_opp'
+ * @node: list node
+ * @dev: device to which the struct object belongs
+ * @rcu_head: RCU callback head used for deferred freeing
+ *
+ * This is an internal data structure maintaining the list of devices that are
+ * managed by 'struct device_opp'.
+ */
+struct device_list_opp {
+ struct list_head node;
+ const struct device *dev;
+ 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
+ * @srcu_head: notifier head to notify the OPP availability changes.
+ * @rcu_head: RCU callback head used for deferred freeing
+ * @dev_list: list of devices that share these OPPs
+ * @opp_list: list of opps
+ * @np: struct device_node pointer for opp's DT node.
+ * @shared_opp: OPP is shared between multiple devices.
+ *
+ * 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 srcu_notifier_head srcu_head;
+ struct rcu_head rcu_head;
+ struct list_head dev_list;
+ struct list_head opp_list;
+
+ struct device_node *np;
+ unsigned long clock_latency_ns_max;
+ bool shared_opp;
+ struct dev_pm_opp *suspend_opp;
+};
+
+/* Routines internal to opp core */
+struct device_opp *_find_device_opp(struct device *dev);
+struct device_list_opp *_add_list_dev(const struct device *dev,
+ struct device_opp *dev_opp);
+struct device_node *_of_get_opp_desc_node(struct device *dev);
+
+#endif /* __DRIVER_OPP_H__ */