mirror of https://gitee.com/openkylin/linux.git
x86/tsc_msr: Update comments, expand definitions
Syntax only, no functional change. Signed-off-by: Len Brown <len.brown@intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/8653a2dba21fef122fc7b29eafb750e2004d3976.1466138954.git.len.brown@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -1,14 +1,5 @@
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/*
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* tsc_msr.c - MSR based TSC calibration on Intel Atom SoC platforms.
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*
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* TSC in Intel Atom SoC runs at a constant rate which can be figured
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* by this formula:
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* <maximum core-clock to bus-clock ratio> * <maximum resolved frequency>
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* See Intel 64 and IA-32 System Programming Guid section 16.12 and 30.11.5
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* for details.
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* Especially some Intel Atom SoCs don't have PIT(i8254) or HPET, so MSR
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* based calibration is the only option.
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*
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* tsc_msr.c - TSC frequency enumeration via MSR
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*
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* Copyright (C) 2013 Intel Corporation
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* Author: Bin Gao <bin.gao@intel.com>
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@ -22,17 +13,10 @@
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#include <asm/apic.h>
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#include <asm/param.h>
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/* CPU reference clock frequency: in KHz */
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#define FREQ_83 83200
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#define FREQ_100 99840
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#define FREQ_133 133200
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#define FREQ_166 166400
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#define MAX_NUM_FREQS 8
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/*
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* According to Intel 64 and IA-32 System Programming Guide,
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* if MSR_PERF_STAT[31] is set, the maximum resolved bus ratio can be
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* If MSR_PERF_STAT[31] is set, the maximum resolved bus ratio can be
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* read in MSR_PLATFORM_ID[12:8], otherwise in MSR_PERF_STAT[44:40].
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* Unfortunately some Intel Atom SoCs aren't quite compliant to this,
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* so we need manually differentiate SoC families. This is what the
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@ -47,15 +31,15 @@ struct freq_desc {
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static struct freq_desc freq_desc_tables[] = {
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/* PNW */
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{ 6, 0x27, 0, { 0, 0, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
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{ 6, 0x27, 0, { 0, 0, 0, 0, 0, 99840, 0, 83200 } },
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/* CLV+ */
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{ 6, 0x35, 0, { 0, FREQ_133, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
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/* TNG */
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{ 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } },
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/* VLV2 */
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{ 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
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/* ANN */
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{ 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } },
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{ 6, 0x35, 0, { 0, 133200, 0, 0, 0, 99840, 0, 83200 } },
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/* TNG - Intel Atom processor Z3400 series */
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{ 6, 0x4a, 1, { 0, 99840, 133200, 0, 0, 0, 0, 0 } },
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/* VLV2 - Intel Atom processor E3000, Z3600, Z3700 series */
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{ 6, 0x37, 1, { 83200, 99840, 133200, 166400, 0, 0, 0, 0 } },
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/* ANN - Intel Atom processor Z3500 series */
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{ 6, 0x5a, 1, { 83200, 99840, 133200, 99840, 0, 0, 0, 0 } },
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};
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static int match_cpu(u8 family, u8 model)
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