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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__ */
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