pexpert/ppc/pe_clock_speed.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  *  pe_clock_speed.c - Determine the best guess for the processor and bus
  27  *                     speed buy using the values returned by run_clock_test.
  28  *
  29  *  (c) Apple Computer, Inc. 1998-2002
  30  *
  31  *  Writen by:   Josh de Cesare
  32  *
  33  */
  34
  35 #include <pexpert/pexpert.h>
  36
  37 #include <ppc/machine_routines.h>
  38
  39 // prototypes
  40 extern void pe_run_clock_test(void *tmp);
  41 void pe_do_clock_test(unsigned int via_addr,
  42                       int num_speeds, unsigned long *speed_list);
  43
  44 // Threshold for bus speed matches.
  45 #define kMaxFreqDiff  (30000)
  46
  47 // This is the structure for the data that get passed to pe_run_clock_test.
  48 struct clock_test_data {
  49   unsigned int via_addr;
  50   unsigned int via_ticks;
  51   unsigned int dec_ticks;
  52 };
  53
  54 // glocal variables to simplify some stuff.
  55 static long bus_freq_num, bus_freq_den, cpu_pll;
  56
  57 // PE_Determine_Clock_Speeds is called by the via driver in IOKit
  58 // It uses the numbers generated by pe_do_clock_test and reports
  59 // the cleaned up values to the rest of the OS.
  60 void PE_Determine_Clock_Speeds(unsigned int via_addr, int num_speeds,
  61                                unsigned long *speed_list)
  62 {
  63   boolean_t          oldLevel;
  64   unsigned long      tmp_bus_speed, tmp_cpu_speed;
  65   unsigned long long tmp;
  66
  67   oldLevel = ml_set_interrupts_enabled(FALSE);
  68   pe_do_clock_test(via_addr, num_speeds, speed_list);
  69   ml_set_interrupts_enabled(oldLevel);
  70
  71   tmp_bus_speed = bus_freq_num / bus_freq_den;
  72   tmp = ((unsigned long long)bus_freq_num * cpu_pll) / (bus_freq_den * 2);
  73   tmp_cpu_speed = (unsigned long)tmp;
  74
  75   // Report the bus clock rate as is.
  76   gPEClockFrequencyInfo.bus_clock_rate_num = bus_freq_num;
  77   gPEClockFrequencyInfo.bus_clock_rate_den = bus_freq_den;
  78
  79   // pll multipliers are in halfs so set the denominator to 2.
  80   gPEClockFrequencyInfo.bus_to_cpu_rate_num = cpu_pll;
  81   gPEClockFrequencyInfo.bus_to_cpu_rate_den = 2;
  82
  83   // The decrementer rate is one fourth the bus rate.
  84   gPEClockFrequencyInfo.bus_to_dec_rate_num = 1;
  85   gPEClockFrequencyInfo.bus_to_dec_rate_den = 4;
  86
  87   // Assume that the timebase frequency is derived from the bus clock.
  88   gPEClockFrequencyInfo.timebase_frequency_num = bus_freq_num;
  89   gPEClockFrequencyInfo.timebase_frequency_den = bus_freq_den * 4;
  90
  91   // Set the truncated numbers in gPEClockFrequencyInfo.
  92   gPEClockFrequencyInfo.bus_clock_rate_hz = tmp_bus_speed;
  93   gPEClockFrequencyInfo.cpu_clock_rate_hz = tmp_cpu_speed;
  94   gPEClockFrequencyInfo.dec_clock_rate_hz = tmp_bus_speed / 4;
  95   gPEClockFrequencyInfo.timebase_frequency_hz = tmp_bus_speed / 4;
  96
  97   gPEClockFrequencyInfo.bus_frequency_hz = tmp_bus_speed;
  98   gPEClockFrequencyInfo.bus_frequency_min_hz = tmp_bus_speed;
  99   gPEClockFrequencyInfo.bus_frequency_max_hz = tmp_bus_speed;
 100   gPEClockFrequencyInfo.cpu_frequency_hz = tmp_cpu_speed;
 101   gPEClockFrequencyInfo.cpu_frequency_min_hz = tmp_cpu_speed;
 102   gPEClockFrequencyInfo.cpu_frequency_max_hz = tmp_cpu_speed;
 103
 104   PE_call_timebase_callback();
 105 }
 106
 107 // pe_do_clock_test uses the number from pe_run_clock_test to
 108 // find a best fit guess for the bus speed.
 109 void pe_do_clock_test(unsigned int via_addr,
 110                       int num_speeds, unsigned long *speed_list)
 111 {
 112   struct clock_test_data clock_test_data;
 113   long cnt, diff, raw_cpu_freq, raw_bus_freq, tmp_bus_freq,
 114     last_bus_freq, tries = 10;
 115
 116   // Save the via addr so the asm part can use it.
 117   clock_test_data.via_addr = via_addr;
 118
 119   // Keep looping until it matches the last try.
 120   bus_freq_num = 0;
 121   do {
 122     last_bus_freq = bus_freq_num;
 123
 124     // The the asm part to do the real work.
 125     pe_run_clock_test((void *)&clock_test_data);
 126
 127     // First find the pll mode.  Allow any integer times two.
 128     cpu_pll = 10000000 / clock_test_data.dec_ticks;
 129     cpu_pll = (cpu_pll / 2) + (cpu_pll & 1);
 130
 131     // Using 64 bit math figure out the raw bus speed.
 132     // 0xBF401675E5DULL is 1 / 1.27655us times 2 ^ 24.
 133     raw_bus_freq = ((0xBF401675E5DULL * clock_test_data.dec_ticks) /
 134                     clock_test_data.via_ticks) >> 22;
 135
 136     // use the pll mode and the raw bus speed to find the raw cpu speed.
 137     raw_cpu_freq = raw_bus_freq * cpu_pll / 2;
 138
 139     // Look to see if the bus speed is close to one of the
 140     // speeds in the table.
 141     for (cnt = 0; cnt < num_speeds; cnt++) {
 142       bus_freq_num = speed_list[cnt * 2];
 143       bus_freq_den = speed_list[cnt * 2 + 1];
 144       diff = bus_freq_num - raw_bus_freq * bus_freq_den;
 145       if (diff < 0) diff = -diff;
 146
 147       if (diff < kMaxFreqDiff * bus_freq_den) break;
 148     }
 149     if (cnt != num_speeds) continue;
 150
 151     // Look to see if the bus speed is close to n * 0.5 MHz
 152     tmp_bus_freq = ((raw_bus_freq + 250000) / 500000) * 500000;
 153
 154     diff = tmp_bus_freq - raw_bus_freq;
 155     if (diff < 0) diff = -diff;
 156
 157     if (diff < kMaxFreqDiff) {
 158       bus_freq_num = tmp_bus_freq;
 159       bus_freq_den = 1;
 160       continue;
 161     }
 162
 163     // Look to see if the bus speed is close to n * 50/3 MHz
 164     tmp_bus_freq = ((raw_bus_freq * 3 + 25000000) / 50000000) * 50000000;
 165
 166     diff = tmp_bus_freq - raw_bus_freq * 3;
 167     if (diff < 0) diff = -diff;
 168
 169     if (diff < kMaxFreqDiff * 3) {
 170       bus_freq_num = tmp_bus_freq;
 171       bus_freq_den = 3;
 172       continue;
 173     }
 174
 175     // Since all else failed return the raw bus speed
 176     bus_freq_num = raw_bus_freq;
 177     bus_freq_den = 1;
 178   } while ((bus_freq_num != last_bus_freq) && tries--);
 179 }