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

   1 /*
   2  * mfld.c: Intel Medfield platform 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 #include <asm/intel_mid_vrtc.h>
  17
  18 #include "intel_mid_weak_decls.h"
  19
  20 static unsigned long __init mfld_calibrate_tsc(void)
  21 {
  22         unsigned long fast_calibrate;
  23         u32 lo, hi, ratio, fsb;
  24
  25         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  26         pr_debug("IA32 perf status is 0x%x, 0x%0x\n", lo, hi);
  27         ratio = (hi >> 8) & 0x1f;
  28         pr_debug("ratio is %d\n", ratio);
  29         if (!ratio) {
  30                 pr_err("read a zero ratio, should be incorrect!\n");
  31                 pr_err("force tsc ratio to 16 ...\n");
  32                 ratio = 16;
  33         }
  34         rdmsr(MSR_FSB_FREQ, lo, hi);
  35         if ((lo & 0x7) == 0x7)
  36                 fsb = FSB_FREQ_83SKU;
  37         else
  38                 fsb = FSB_FREQ_100SKU;
  39         fast_calibrate = ratio * fsb;
  40         pr_debug("read penwell tsc %lu khz\n", fast_calibrate);
  41         lapic_timer_frequency = fsb * 1000 / HZ;
  42
  43         /*
  44          * TSC on Intel Atom SoCs is reliable and of known frequency.
  45          * See tsc_msr.c for details.
  46          */
  47         setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
  48         setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
  49
  50         return fast_calibrate;
  51 }
  52
  53 static void __init penwell_arch_setup(void)
  54 {
  55         x86_platform.calibrate_tsc = mfld_calibrate_tsc;
  56 }
  57
  58 static struct intel_mid_ops penwell_ops = {
  59         .arch_setup = penwell_arch_setup,
  60 };
  61
  62 void *get_penwell_ops(void)
  63 {
  64         return &penwell_ops;
  65 }
  66
  67 void *get_cloverview_ops(void)
  68 {
  69         return &penwell_ops;
  70 }