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