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  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  *  pe_clock_speed.c - Determine the best guess for the processor and bus
  24  *                     speed buy using the values returned by run_clock_test.
  25  *
  26  *  (c) Apple Computer, Inc. 1998-2000
  27  *
  28  *  Writen by:   Josh de Cesare
  29  *
  30  */
  31
  32 #include <pexpert/pexpert.h>
  33
  34 #include <ppc/machine_routines.h>
  35
  36 // prototypes
  37 extern void pe_run_clock_test(void *tmp);
  38 void pe_do_clock_test(unsigned int via_addr,
  39                       int num_speeds, unsigned long *speed_list);
  40
  41 // Threshold for bus speed matches.
  42 #define kMaxFreqDiff  (30000)
  43
  44 // This is the structure for the data that get passed to pe_run_clock_test.
  45 struct clock_test_data {
  46   unsigned int via_addr;
  47   unsigned int via_ticks;
  48   unsigned int dec_ticks;
  49 };
  50
  51 // glocal variables to simplify some stuff.
  52 static long bus_freq_num, bus_freq_den, cpu_pll;
  53
  54 // PE_Determine_Clock_Speeds is called by the via driver in IOKit
  55 // It uses the numbers generated by pe_do_clock_test and reports
  56 // the cleaned up values to the rest of the OS.
  57 void PE_Determine_Clock_Speeds(unsigned int via_addr, int num_speeds,
  58                                unsigned long *speed_list)
  59 {
  60   boolean_t          oldLevel;
  61   unsigned long      tmp_bus_speed, tmp_cpu_speed;
  62   unsigned long long tmp;
  63
  64   oldLevel = ml_set_interrupts_enabled(FALSE);
  65   pe_do_clock_test(via_addr, num_speeds, speed_list);
  66   ml_set_interrupts_enabled(oldLevel);
  67
  68   tmp_bus_speed = bus_freq_num / bus_freq_den;
  69   tmp = ((unsigned long long)bus_freq_num * cpu_pll) / (bus_freq_den * 2);
  70   tmp_cpu_speed = (unsigned long)tmp;
  71
  72   // Report the bus clock rate as is.
  73   gPEClockFrequencyInfo.bus_clock_rate_num = bus_freq_num;
  74   gPEClockFrequencyInfo.bus_clock_rate_den = bus_freq_den;
  75
  76   // pll multipliers are in halfs so set the denominator to 2.
  77   gPEClockFrequencyInfo.bus_to_cpu_rate_num = cpu_pll;
  78   gPEClockFrequencyInfo.bus_to_cpu_rate_den = 2;
  79
  80   // The decrementer rate is one fourth the bus rate.
  81   gPEClockFrequencyInfo.bus_to_dec_rate_num = 1;
  82   gPEClockFrequencyInfo.bus_to_dec_rate_den = 4;
  83
  84   // Set the truncated numbers in gPEClockFrequencyInfo.
  85   gPEClockFrequencyInfo.bus_clock_rate_hz = tmp_bus_speed;
  86   gPEClockFrequencyInfo.cpu_clock_rate_hz = tmp_cpu_speed;
  87   gPEClockFrequencyInfo.dec_clock_rate_hz = tmp_bus_speed / 4;
  88
  89   PE_call_timebase_callback();
  90 }
  91
  92 // pe_do_clock_test uses the number from pe_run_clock_test to
  93 // find a best fit guess for the bus speed.
  94 void pe_do_clock_test(unsigned int via_addr,
  95                       int num_speeds, unsigned long *speed_list)
  96 {
  97   struct clock_test_data clock_test_data;
  98   long cnt, diff, raw_cpu_freq, raw_bus_freq, tmp_bus_freq,
  99     last_bus_freq, tries = 10;
 100
 101   // Save the via addr so the asm part can use it.
 102   clock_test_data.via_addr = via_addr;
 103
 104   // Keep looping until it matches the last try.
 105   bus_freq_num = 0;
 106   do {
 107     last_bus_freq = bus_freq_num;
 108
 109     // The the asm part to do the real work.
 110     pe_run_clock_test((void *)&clock_test_data);
 111
 112     // First find the pll mode.  Allow any integer times two.
 113     cpu_pll = 10000000 / clock_test_data.dec_ticks;
 114     cpu_pll = (cpu_pll / 2) + (cpu_pll & 1);
 115
 116     // Using 64 bit math figure out the raw bus speed.
 117     // 0xBF401675E5DULL is 1 / 1.27655us times 2 ^ 24.
 118     raw_bus_freq = ((0xBF401675E5DULL * clock_test_data.dec_ticks) /
 119                     clock_test_data.via_ticks) >> 22;
 120
 121     // use the pll mode and the raw bus speed to find the raw cpu speed.
 122     raw_cpu_freq = raw_bus_freq * cpu_pll / 2;
 123
 124     // Look to see if the bus speed is close to one of the
 125     // speeds in the table.
 126     for (cnt = 0; cnt < num_speeds; cnt++) {
 127       bus_freq_num = speed_list[cnt * 2];
 128       bus_freq_den = speed_list[cnt * 2 + 1];
 129       diff = bus_freq_num - raw_bus_freq * bus_freq_den;
 130       if (diff < 0) diff = -diff;
 131
 132       if (diff < kMaxFreqDiff * bus_freq_den) break;
 133     }
 134     if (cnt != num_speeds) continue;
 135
 136     // Look to see if the bus speed is close to n * 0.5 MHz
 137     tmp_bus_freq = ((raw_bus_freq + 250000) / 500000) * 500000;
 138
 139     diff = tmp_bus_freq - raw_bus_freq;
 140     if (diff < 0) diff = -diff;
 141
 142     if (diff < kMaxFreqDiff) {
 143       bus_freq_num = tmp_bus_freq;
 144       bus_freq_den = 1;
 145       continue;
 146     }
 147
 148     // Look to see if the bus speed is close to n * 50/3 MHz
 149     tmp_bus_freq = ((raw_bus_freq * 3 + 25000000) / 50000000) * 50000000;
 150
 151     diff = tmp_bus_freq - raw_bus_freq * 3;
 152     if (diff < 0) diff = -diff;
 153
 154     if (diff < kMaxFreqDiff * 3) {
 155       bus_freq_num = tmp_bus_freq;
 156       bus_freq_den = 3;
 157       continue;
 158     }
 159
 160     // Since all else failed return the raw bus speed
 161     bus_freq_num = raw_bus_freq;
 162     bus_freq_den = 1;
 163   } while ((bus_freq_num != last_bus_freq) && tries--);
 164 }