The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/cpu.h

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    1 /*-
    2  * Copyright (c) 2005-2007 Nate Lawson (SDG)
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD$
   27  */
   28 
   29 #ifndef _SYS_CPU_H_
   30 #define _SYS_CPU_H_
   31 
   32 #include <sys/eventhandler.h>
   33 
   34 /*
   35  * CPU device support.
   36  */
   37 
   38 #define CPU_IVAR_PCPU           1
   39 
   40 static __inline struct pcpu *cpu_get_pcpu(device_t dev)
   41 {
   42         uintptr_t v = 0;
   43         BUS_READ_IVAR(device_get_parent(dev), dev, CPU_IVAR_PCPU, &v);
   44         return ((struct pcpu *)v);
   45 }
   46 
   47 /*
   48  * CPU frequency control interface.
   49  */
   50 
   51 /* Each driver's CPU frequency setting is exported in this format. */
   52 struct cf_setting {
   53         int     freq;   /* CPU clock in Mhz or 100ths of a percent. */
   54         int     volts;  /* Voltage in mV. */
   55         int     power;  /* Power consumed in mW. */
   56         int     lat;    /* Transition latency in us. */
   57         device_t dev;   /* Driver providing this setting. */
   58         int     spec[4];/* Driver-specific storage for non-standard info. */
   59 };
   60 
   61 /* Maximum number of settings a given driver can have. */
   62 #define MAX_SETTINGS            24
   63 
   64 /* A combination of settings is a level. */
   65 struct cf_level {
   66         struct cf_setting       total_set;
   67         struct cf_setting       abs_set;
   68         struct cf_setting       rel_set[MAX_SETTINGS];
   69         int                     rel_count;
   70         TAILQ_ENTRY(cf_level)   link;
   71 };
   72 
   73 TAILQ_HEAD(cf_level_lst, cf_level);
   74 
   75 /* Drivers should set all unknown values to this. */
   76 #define CPUFREQ_VAL_UNKNOWN     (-1)
   77 
   78 /*
   79  * Every driver offers a type of CPU control.  Absolute levels are mutually
   80  * exclusive while relative levels modify the current absolute level.  There
   81  * may be multiple absolute and relative drivers available on a given
   82  * system.
   83  *
   84  * For example, consider a system with two absolute drivers that provide
   85  * frequency settings of 100, 200 and 300, 400 and a relative driver that
   86  * provides settings of 50%, 100%.  The cpufreq core would export frequency
   87  * levels of 50, 100, 150, 200, 300, 400.
   88  *
   89  * The "info only" flag signifies that settings returned by
   90  * CPUFREQ_DRV_SETTINGS cannot be passed to the CPUFREQ_DRV_SET method and
   91  * are only informational.  This is for some drivers that can return
   92  * information about settings but rely on another machine-dependent driver
   93  * for actually performing the frequency transition (e.g., ACPI performance
   94  * states of type "functional fixed hardware.")
   95  */
   96 #define CPUFREQ_TYPE_MASK       0xffff
   97 #define CPUFREQ_TYPE_RELATIVE   (1<<0)
   98 #define CPUFREQ_TYPE_ABSOLUTE   (1<<1)
   99 #define CPUFREQ_FLAG_INFO_ONLY  (1<<16)
  100 
  101 /*
  102  * When setting a level, the caller indicates the priority of this request.
  103  * Priorities determine, among other things, whether a level can be
  104  * overridden by other callers.  For example, if the user sets a level but
  105  * the system thermal driver needs to override it for emergency cooling,
  106  * the driver would use a higher priority.  Once the event has passed, the
  107  * driver would call cpufreq to resume any previous level.
  108  */
  109 #define CPUFREQ_PRIO_HIGHEST    1000000
  110 #define CPUFREQ_PRIO_KERN       1000
  111 #define CPUFREQ_PRIO_USER       100
  112 #define CPUFREQ_PRIO_LOWEST     0
  113 
  114 /*
  115  * Register and unregister a driver with the cpufreq core.  Once a driver
  116  * is registered, it must support calls to its CPUFREQ_GET, CPUFREQ_GET_LEVEL,
  117  * and CPUFREQ_SET methods.  It must also unregister before returning from
  118  * its DEVICE_DETACH method.
  119  */
  120 int     cpufreq_register(device_t dev);
  121 int     cpufreq_unregister(device_t dev);
  122 
  123 /*
  124  * Notify the cpufreq core that the number of or values for settings have
  125  * changed.
  126  */
  127 int     cpufreq_settings_changed(device_t dev);
  128 
  129 /*
  130  * Eventhandlers that are called before and after a change in frequency.
  131  * The new level and the result of the change (0 is success) is passed in.
  132  * If the driver wishes to revoke the change from cpufreq_pre_change, it
  133  * stores a non-zero error code in the result parameter and the change will
  134  * not be made.  If the post-change eventhandler gets a non-zero result, 
  135  * no change was made and the previous level remains in effect.  If a change
  136  * is revoked, the post-change eventhandler is still called with the error
  137  * value supplied by the revoking driver.  This gives listeners who cached
  138  * some data in preparation for a level change a chance to clean up.
  139  */
  140 typedef void (*cpufreq_pre_notify_fn)(void *, const struct cf_level *, int *);
  141 typedef void (*cpufreq_post_notify_fn)(void *, const struct cf_level *, int);
  142 EVENTHANDLER_DECLARE(cpufreq_pre_change, cpufreq_pre_notify_fn);
  143 EVENTHANDLER_DECLARE(cpufreq_post_change, cpufreq_post_notify_fn);
  144 
  145 /*
  146  * Eventhandler called when the available list of levels changed.
  147  * The unit number of the device (i.e. "cpufreq0") whose levels changed
  148  * is provided so the listener can retrieve the new list of levels.
  149  */
  150 typedef void (*cpufreq_levels_notify_fn)(void *, int);
  151 EVENTHANDLER_DECLARE(cpufreq_levels_changed, cpufreq_levels_notify_fn);
  152 
  153 /* Allow values to be +/- a bit since sometimes we have to estimate. */
  154 #define CPUFREQ_CMP(x, y)       (abs((x) - (y)) < 25)
  155 
  156 /*
  157  * Machine-dependent functions.
  158  */
  159 
  160 /* Estimate the current clock rate for the given CPU id. */
  161 int     cpu_est_clockrate(int cpu_id, uint64_t *rate);
  162 
  163 #endif /* !_SYS_CPU_H_ */

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