LXR linux/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
  19static 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
  91static 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 */
  98static struct intel_mid_ops tangier_ops = {
  99        .arch_setup = tangier_arch_setup,
 100};
 101
 102void *get_tangier_ops(void)
 103{
 104        return &tangier_ops;
 105}
 106