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 void penwell_arch_setup(void);
  21 /* penwell arch ops */
  22 static struct intel_mid_ops penwell_ops = {
  23         .arch_setup = penwell_arch_setup,
  24 };
  25
  26 static void mfld_power_off(void)
  27 {
  28 }
  29
  30 static unsigned long __init mfld_calibrate_tsc(void)
  31 {
  32         unsigned long fast_calibrate;
  33         u32 lo, hi, ratio, fsb;
  34
  35         rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
  36         pr_debug("IA32 perf status is 0x%x, 0x%0x\n", lo, hi);
  37         ratio = (hi >> 8) & 0x1f;
  38         pr_debug("ratio is %d\n", ratio);
  39         if (!ratio) {
  40                 pr_err("read a zero ratio, should be incorrect!\n");
  41                 pr_err("force tsc ratio to 16 ...\n");
  42                 ratio = 16;
  43         }
  44         rdmsr(MSR_FSB_FREQ, lo, hi);
  45         if ((lo & 0x7) == 0x7)
  46                 fsb = FSB_FREQ_83SKU;
  47         else
  48                 fsb = FSB_FREQ_100SKU;
  49         fast_calibrate = ratio * fsb;
  50         pr_debug("read penwell tsc %lu khz\n", fast_calibrate);
  51         lapic_timer_frequency = fsb * 1000 / HZ;
  52
  53         /*
  54          * TSC on Intel Atom SoCs is reliable and of known frequency.
  55          * See tsc_msr.c for details.
  56          */
  57         setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
  58         setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
  59
  60         return fast_calibrate;
  61 }
  62
  63 static void __init penwell_arch_setup(void)
  64 {
  65         x86_platform.calibrate_tsc = mfld_calibrate_tsc;
  66         pm_power_off = mfld_power_off;
  67 }
  68
  69 void *get_penwell_ops(void)
  70 {
  71         return &penwell_ops;
  72 }
  73
  74 void *get_cloverview_ops(void)
  75 {
  76         return &penwell_ops;
  77 }