diff options
Diffstat (limited to 'arch/x86/kernel/tsc_msr.c')
| -rw-r--r-- | arch/x86/kernel/tsc_msr.c | 68 |
1 files changed, 21 insertions, 47 deletions
diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c index 9911a0620f9a..0fe720d64fef 100644 --- a/arch/x86/kernel/tsc_msr.c +++ b/arch/x86/kernel/tsc_msr.c @@ -1,14 +1,5 @@ /* - * tsc_msr.c - MSR based TSC calibration on Intel Atom SoC platforms. - * - * TSC in Intel Atom SoC runs at a constant rate which can be figured - * by this formula: - * <maximum core-clock to bus-clock ratio> * <maximum resolved frequency> - * See Intel 64 and IA-32 System Programming Guid section 16.12 and 30.11.5 - * for details. - * Especially some Intel Atom SoCs don't have PIT(i8254) or HPET, so MSR - * based calibration is the only option. - * + * tsc_msr.c - TSC frequency enumeration via MSR * * Copyright (C) 2013 Intel Corporation * Author: Bin Gao <bin.gao@intel.com> @@ -22,18 +13,10 @@ #include <asm/apic.h> #include <asm/param.h> -/* CPU reference clock frequency: in KHz */ -#define FREQ_80 80000 -#define FREQ_83 83200 -#define FREQ_100 99840 -#define FREQ_133 133200 -#define FREQ_166 166400 - -#define MAX_NUM_FREQS 8 +#define MAX_NUM_FREQS 9 /* - * According to Intel 64 and IA-32 System Programming Guide, - * if MSR_PERF_STAT[31] is set, the maximum resolved bus ratio can be + * If MSR_PERF_STAT[31] is set, the maximum resolved bus ratio can be * read in MSR_PLATFORM_ID[12:8], otherwise in MSR_PERF_STAT[44:40]. * Unfortunately some Intel Atom SoCs aren't quite compliant to this, * so we need manually differentiate SoC families. This is what the @@ -48,17 +31,18 @@ struct freq_desc { static struct freq_desc freq_desc_tables[] = { /* PNW */ - { 6, 0x27, 0, { 0, 0, 0, 0, 0, FREQ_100, 0, FREQ_83 } }, + { 6, 0x27, 0, { 0, 0, 0, 0, 0, 99840, 0, 83200 } }, /* CLV+ */ - { 6, 0x35, 0, { 0, FREQ_133, 0, 0, 0, FREQ_100, 0, FREQ_83 } }, - /* TNG */ - { 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } }, - /* VLV2 */ - { 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } }, - /* ANN */ - { 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } }, - /* AIRMONT */ - { 6, 0x4c, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, FREQ_80, 0, 0, 0 } }, + { 6, 0x35, 0, { 0, 133200, 0, 0, 0, 99840, 0, 83200 } }, + /* TNG - Intel Atom processor Z3400 series */ + { 6, 0x4a, 1, { 0, 100000, 133300, 0, 0, 0, 0, 0 } }, + /* VLV2 - Intel Atom processor E3000, Z3600, Z3700 series */ + { 6, 0x37, 1, { 83300, 100000, 133300, 116700, 80000, 0, 0, 0 } }, + /* ANN - Intel Atom processor Z3500 series */ + { 6, 0x5a, 1, { 83300, 100000, 133300, 100000, 0, 0, 0, 0 } }, + /* AMT - Intel Atom processor X7-Z8000 and X5-Z8000 series */ + { 6, 0x4c, 1, { 83300, 100000, 133300, 116700, + 80000, 93300, 90000, 88900, 87500 } }, }; static int match_cpu(u8 family, u8 model) @@ -79,16 +63,20 @@ static int match_cpu(u8 family, u8 model) (freq_desc_tables[cpu_index].freqs[freq_id]) /* - * Do MSR calibration only for known/supported CPUs. + * MSR-based CPU/TSC frequency discovery for certain CPUs. * - * Returns the calibration value or 0 if MSR calibration failed. + * Set global "lapic_timer_frequency" to bus_clock_cycles/jiffy + * Return processor base frequency in KHz, or 0 on failure. */ -unsigned long try_msr_calibrate_tsc(void) +unsigned long cpu_khz_from_msr(void) { u32 lo, hi, ratio, freq_id, freq; unsigned long res; int cpu_index; + if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) + return 0; + cpu_index = match_cpu(boot_cpu_data.x86, boot_cpu_data.x86_model); if (cpu_index < 0) return 0; @@ -100,31 +88,17 @@ unsigned long try_msr_calibrate_tsc(void) rdmsr(MSR_IA32_PERF_STATUS, lo, hi); ratio = (hi >> 8) & 0x1f; } - pr_info("Maximum core-clock to bus-clock ratio: 0x%x\n", ratio); - - if (!ratio) - goto fail; /* Get FSB FREQ ID */ rdmsr(MSR_FSB_FREQ, lo, hi); freq_id = lo & 0x7; freq = id_to_freq(cpu_index, freq_id); - pr_info("Resolved frequency ID: %u, frequency: %u KHz\n", - freq_id, freq); - if (!freq) - goto fail; /* TSC frequency = maximum resolved freq * maximum resolved bus ratio */ res = freq * ratio; - pr_info("TSC runs at %lu KHz\n", res); #ifdef CONFIG_X86_LOCAL_APIC lapic_timer_frequency = (freq * 1000) / HZ; - pr_info("lapic_timer_frequency = %d\n", lapic_timer_frequency); #endif return res; - -fail: - pr_warn("Fast TSC calibration using MSR failed\n"); - return 0; } |