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. 1998-2002
  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   // Assume that the timebase frequency is derived from the bus clock.
  85   gPEClockFrequencyInfo.timebase_frequency_num = bus_freq_num;
  86   gPEClockFrequencyInfo.timebase_frequency_den = bus_freq_den * 4;
  87
  88   // Set the truncated numbers in gPEClockFrequencyInfo.
  89   gPEClockFrequencyInfo.bus_clock_rate_hz = tmp_bus_speed;
  90   gPEClockFrequencyInfo.cpu_clock_rate_hz = tmp_cpu_speed;
  91   gPEClockFrequencyInfo.dec_clock_rate_hz = tmp_bus_speed / 4;
  92   gPEClockFrequencyInfo.timebase_frequency_hz = tmp_bus_speed / 4;
  93
  94   PE_call_timebase_callback();
  95 }
  96
  97 // pe_do_clock_test uses the number from pe_run_clock_test to
  98 // find a best fit guess for the bus speed.
  99 void pe_do_clock_test(unsigned int via_addr,
 100                       int num_speeds, unsigned long *speed_list)
 101 {
 102   struct clock_test_data clock_test_data;
 103   long cnt, diff, raw_cpu_freq, raw_bus_freq, tmp_bus_freq,
 104     last_bus_freq, tries = 10;
 105
 106   // Save the via addr so the asm part can use it.
 107   clock_test_data.via_addr = via_addr;
 108
 109   // Keep looping until it matches the last try.
 110   bus_freq_num = 0;
 111   do {
 112     last_bus_freq = bus_freq_num;
 113
 114     // The the asm part to do the real work.
 115     pe_run_clock_test((void *)&clock_test_data);
 116
 117     // First find the pll mode.  Allow any integer times two.
 118     cpu_pll = 10000000 / clock_test_data.dec_ticks;
 119     cpu_pll = (cpu_pll / 2) + (cpu_pll & 1);
 120
 121     // Using 64 bit math figure out the raw bus speed.
 122     // 0xBF401675E5DULL is 1 / 1.27655us times 2 ^ 24.
 123     raw_bus_freq = ((0xBF401675E5DULL * clock_test_data.dec_ticks) /
 124                     clock_test_data.via_ticks) >> 22;
 125
 126     // use the pll mode and the raw bus speed to find the raw cpu speed.
 127     raw_cpu_freq = raw_bus_freq * cpu_pll / 2;
 128
 129     // Look to see if the bus speed is close to one of the
 130     // speeds in the table.
 131     for (cnt = 0; cnt < num_speeds; cnt++) {
 132       bus_freq_num = speed_list[cnt * 2];
 133       bus_freq_den = speed_list[cnt * 2 + 1];
 134       diff = bus_freq_num - raw_bus_freq * bus_freq_den;
 135       if (diff < 0) diff = -diff;
 136
 137       if (diff < kMaxFreqDiff * bus_freq_den) break;
 138     }
 139     if (cnt != num_speeds) continue;
 140
 141     // Look to see if the bus speed is close to n * 0.5 MHz
 142     tmp_bus_freq = ((raw_bus_freq + 250000) / 500000) * 500000;
 143
 144     diff = tmp_bus_freq - raw_bus_freq;
 145     if (diff < 0) diff = -diff;
 146
 147     if (diff < kMaxFreqDiff) {
 148       bus_freq_num = tmp_bus_freq;
 149       bus_freq_den = 1;
 150       continue;
 151     }
 152
 153     // Look to see if the bus speed is close to n * 50/3 MHz
 154     tmp_bus_freq = ((raw_bus_freq * 3 + 25000000) / 50000000) * 50000000;
 155
 156     diff = tmp_bus_freq - raw_bus_freq * 3;
 157     if (diff < 0) diff = -diff;
 158
 159     if (diff < kMaxFreqDiff * 3) {
 160       bus_freq_num = tmp_bus_freq;
 161       bus_freq_den = 3;
 162       continue;
 163     }
 164
 165     // Since all else failed return the raw bus speed
 166     bus_freq_num = raw_bus_freq;
 167     bus_freq_den = 1;
 168   } while ((bus_freq_num != last_bus_freq) && tries--);
 169 }