drivers/base/power/opp/opp.h

   1 /*
   2  * Generic OPP Interface
   3  *
   4  * Copyright (C) 2009-2010 Texas Instruments Incorporated.
   5  *      Nishanth Menon
   6  *      Romit Dasgupta
   7  *      Kevin Hilman
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #ifndef __DRIVER_OPP_H__
  15 #define __DRIVER_OPP_H__
  16
  17 #include <linux/device.h>
  18 #include <linux/kernel.h>
  19 #include <linux/list.h>
  20 #include <linux/pm_opp.h>
  21 #include <linux/rculist.h>
  22 #include <linux/rcupdate.h>
  23
  24 /* Lock to allow exclusive modification to the device and opp lists */
  25 extern struct mutex dev_opp_list_lock;
  26
  27 /*
  28  * Internal data structure organization with the OPP layer library is as
  29  * follows:
  30  * dev_opp_list (root)
  31  *      |- device 1 (represents voltage domain 1)
  32  *      |       |- opp 1 (availability, freq, voltage)
  33  *      |       |- opp 2 ..
  34  *      ...     ...
  35  *      |       `- opp n ..
  36  *      |- device 2 (represents the next voltage domain)
  37  *      ...
  38  *      `- device m (represents mth voltage domain)
  39  * device 1, 2.. are represented by dev_opp structure while each opp
  40  * is represented by the opp structure.
  41  */
  42
  43 /**
  44  * struct dev_pm_opp - Generic OPP description structure
  45  * @node:       opp list node. The nodes are maintained throughout the lifetime
  46  *              of boot. It is expected only an optimal set of OPPs are
  47  *              added to the library by the SoC framework.
  48  *              RCU usage: opp list is traversed with RCU locks. node
  49  *              modification is possible realtime, hence the modifications
  50  *              are protected by the dev_opp_list_lock for integrity.
  51  *              IMPORTANT: the opp nodes should be maintained in increasing
  52  *              order.
  53  * @dynamic:    not-created from static DT entries.
  54  * @available:  true/false - marks if this OPP as available or not
  55  * @turbo:      true if turbo (boost) OPP
  56  * @rate:       Frequency in hertz
  57  * @u_volt:     Target voltage in microvolts corresponding to this OPP
  58  * @u_volt_min: Minimum voltage in microvolts corresponding to this OPP
  59  * @u_volt_max: Maximum voltage in microvolts corresponding to this OPP
  60  * @u_amp:      Maximum current drawn by the device in microamperes
  61  * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
  62  *              frequency from any other OPP's frequency.
  63  * @dev_opp:    points back to the device_opp struct this opp belongs to
  64  * @rcu_head:   RCU callback head used for deferred freeing
  65  * @np:         OPP's device node.
  66  *
  67  * This structure stores the OPP information for a given device.
  68  */
  69 struct dev_pm_opp {
  70         struct list_head node;
  71
  72         bool available;
  73         bool dynamic;
  74         bool turbo;
  75         unsigned long rate;
  76
  77         unsigned long u_volt;
  78         unsigned long u_volt_min;
  79         unsigned long u_volt_max;
  80         unsigned long u_amp;
  81         unsigned long clock_latency_ns;
  82
  83         struct device_opp *dev_opp;
  84         struct rcu_head rcu_head;
  85
  86         struct device_node *np;
  87 };
  88
  89 /**
  90  * struct device_list_opp - devices managed by 'struct device_opp'
  91  * @node:       list node
  92  * @dev:        device to which the struct object belongs
  93  * @rcu_head:   RCU callback head used for deferred freeing
  94  *
  95  * This is an internal data structure maintaining the list of devices that are
  96  * managed by 'struct device_opp'.
  97  */
  98 struct device_list_opp {
  99         struct list_head node;
 100         const struct device *dev;
 101         struct rcu_head rcu_head;
 102 };
 103
 104 /**
 105  * struct device_opp - Device opp structure
 106  * @node:       list node - contains the devices with OPPs that
 107  *              have been registered. Nodes once added are not modified in this
 108  *              list.
 109  *              RCU usage: nodes are not modified in the list of device_opp,
 110  *              however addition is possible and is secured by dev_opp_list_lock
 111  * @srcu_head:  notifier head to notify the OPP availability changes.
 112  * @rcu_head:   RCU callback head used for deferred freeing
 113  * @dev_list:   list of devices that share these OPPs
 114  * @opp_list:   list of opps
 115  * @np:         struct device_node pointer for opp's DT node.
 116  * @shared_opp: OPP is shared between multiple devices.
 117  *
 118  * This is an internal data structure maintaining the link to opps attached to
 119  * a device. This structure is not meant to be shared to users as it is
 120  * meant for book keeping and private to OPP library.
 121  *
 122  * Because the opp structures can be used from both rcu and srcu readers, we
 123  * need to wait for the grace period of both of them before freeing any
 124  * resources. And so we have used kfree_rcu() from within call_srcu() handlers.
 125  */
 126 struct device_opp {
 127         struct list_head node;
 128
 129         struct srcu_notifier_head srcu_head;
 130         struct rcu_head rcu_head;
 131         struct list_head dev_list;
 132         struct list_head opp_list;
 133
 134         struct device_node *np;
 135         unsigned long clock_latency_ns_max;
 136         bool shared_opp;
 137         struct dev_pm_opp *suspend_opp;
 138 };
 139
 140 /* Routines internal to opp core */
 141 struct device_opp *_find_device_opp(struct device *dev);
 142 struct device_list_opp *_add_list_dev(const struct device *dev,
 143                                       struct device_opp *dev_opp);
 144 struct device_node *_of_get_opp_desc_node(struct device *dev);
 145
 146 #endif          /* __DRIVER_OPP_H__ */