arch/x86/platform/intel-mid/mrfld.c

   1 /*
   2  * Intel Merrifield platform specific setup code
   3  *
   4  * (C) Copyright 2013 Intel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; version 2
   9  * of the License.
  10  */
  11
  12 #include <linux/init.h>
  13
  14 #include <asm/apic.h>
  15 #include <asm/intel-mid.h>
  16
  17 #include "intel_mid_weak_decls.h"
  18
  19 static unsigned long __init tangier_calibrate_tsc(void)
  20 {
  21         unsigned long fast_calibrate;
  22         u32 lo, hi, ratio, fsb, bus_freq;
  23
  24         /* *********************** */
  25         /* Compute TSC:Ratio * FSB */
  26         /* *********************** */
  27
  28         /* Compute Ratio */
  29         rdmsr(MSR_PLATFORM_INFO, lo, hi);
  30         pr_debug("IA32 PLATFORM_INFO is 0x%x : %x\n", hi, lo);
  31
  32         ratio = (lo >> 8) & 0xFF;
  33         pr_debug("ratio is %d\n", ratio);
  34         if (!ratio) {
  35                 pr_err("Read a zero ratio, force tsc ratio to 4 ...\n");
  36                 ratio = 4;
  37         }
  38
  39         /* Compute FSB */
  40         rdmsr(MSR_FSB_FREQ, lo, hi);
  41         pr_debug("Actual FSB frequency detected by SOC 0x%x : %x\n",
  42                         hi, lo);
  43
  44         bus_freq = lo & 0x7;
  45         pr_debug("bus_freq = 0x%x\n", bus_freq);
  46
  47         if (bus_freq == 0)
  48                 fsb = FSB_FREQ_100SKU;
  49         else if (bus_freq == 1)
  50                 fsb = FSB_FREQ_100SKU;
  51         else if (bus_freq == 2)
  52                 fsb = FSB_FREQ_133SKU;
  53         else if (bus_freq == 3)
  54                 fsb = FSB_FREQ_167SKU;
  55         else if (bus_freq == 4)
  56                 fsb = FSB_FREQ_83SKU;
  57         else if (bus_freq == 5)
  58                 fsb = FSB_FREQ_400SKU;
  59         else if (bus_freq == 6)
  60                 fsb = FSB_FREQ_267SKU;
  61         else if (bus_freq == 7)
  62                 fsb = FSB_FREQ_333SKU;
  63         else {
  64                 BUG();
  65                 pr_err("Invalid bus_freq! Setting to minimal value!\n");
  66                 fsb = FSB_FREQ_100SKU;
  67         }
  68
  69         /* TSC = FSB Freq * Resolved HFM Ratio */
  70         fast_calibrate = ratio * fsb;
  71         pr_debug("calculate tangier tsc %lu KHz\n", fast_calibrate);
  72
  73         /* ************************************ */
  74         /* Calculate Local APIC Timer Frequency */
  75         /* ************************************ */
  76         lapic_timer_frequency = (fsb * 1000) / HZ;
  77
  78         pr_debug("Setting lapic_timer_frequency = %d\n",
  79                         lapic_timer_frequency);
  80
  81         /*
  82          * TSC on Intel Atom SoCs is reliable and of known frequency.
  83          * See tsc_msr.c for details.
  84          */
  85         setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
  86         setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
  87
  88         return fast_calibrate;
  89 }
  90
  91 static void __init tangier_arch_setup(void)
  92 {
  93         x86_platform.calibrate_tsc = tangier_calibrate_tsc;
  94         x86_platform.legacy.rtc = 1;
  95 }
  96
  97 /* tangier arch ops */
  98 static struct intel_mid_ops tangier_ops = {
  99         .arch_setup = tangier_arch_setup,
 100 };
 101
 102 void *get_tangier_ops(void)
 103 {
 104         return &tangier_ops;
 105 }