diff options
| -rw-r--r-- | arch/x86/lib/tsc_timer.c | 115 |
1 files changed, 108 insertions, 7 deletions
diff --git a/arch/x86/lib/tsc_timer.c b/arch/x86/lib/tsc_timer.c index 8b38702..7cdde4a 100644 --- a/arch/x86/lib/tsc_timer.c +++ b/arch/x86/lib/tsc_timer.c @@ -1,6 +1,9 @@ /* * Copyright (c) 2012 The Chromium OS Authors. * + * TSC calibration codes are adapted from Linux kernel + * arch/x86/kernel/tsc_msr.c and arch/x86/kernel/tsc.c + * * SPDX-License-Identifier: GPL-2.0+ */ @@ -12,8 +15,107 @@ #include <asm/msr.h> #include <asm/u-boot-x86.h> +/* CPU reference clock frequency: in KHz */ +#define FREQ_83 83200 +#define FREQ_100 99840 +#define FREQ_133 133200 +#define FREQ_166 166400 + +#define MAX_NUM_FREQS 8 + DECLARE_GLOBAL_DATA_PTR; +/* + * According to Intel 64 and IA-32 System Programming Guide, + * 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 + * field msr_plat does. + */ +struct freq_desc { + u8 x86_family; /* CPU family */ + u8 x86_model; /* model */ + u8 msr_plat; /* 1: use MSR_PLATFORM_INFO, 0: MSR_IA32_PERF_STATUS */ + u32 freqs[MAX_NUM_FREQS]; +}; + +static struct freq_desc freq_desc_tables[] = { + /* PNW */ + { 6, 0x27, 0, { 0, 0, 0, 0, 0, FREQ_100, 0, FREQ_83 } }, + /* 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 } }, +}; + +static int match_cpu(u8 family, u8 model) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(freq_desc_tables); i++) { + if ((family == freq_desc_tables[i].x86_family) && + (model == freq_desc_tables[i].x86_model)) + return i; + } + + return -1; +} + +/* Map CPU reference clock freq ID(0-7) to CPU reference clock freq(KHz) */ +#define id_to_freq(cpu_index, freq_id) \ + (freq_desc_tables[cpu_index].freqs[freq_id]) + +/* + * Do MSR calibration only for known/supported CPUs. + * + * Returns the calibration value or 0 if MSR calibration failed. + */ +static unsigned long try_msr_calibrate_tsc(void) +{ + u32 lo, hi, ratio, freq_id, freq; + unsigned long res; + int cpu_index; + + cpu_index = match_cpu(gd->arch.x86, gd->arch.x86_model); + if (cpu_index < 0) + return 0; + + if (freq_desc_tables[cpu_index].msr_plat) { + rdmsr(MSR_PLATFORM_INFO, lo, hi); + ratio = (lo >> 8) & 0x1f; + } else { + rdmsr(MSR_IA32_PERF_STATUS, lo, hi); + ratio = (hi >> 8) & 0x1f; + } + debug("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); + debug("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 / 1000; + debug("TSC runs at %lu MHz\n", res); + + return res; + +fail: + debug("Fast TSC calibration using MSR failed\n"); + return 0; +} + void timer_set_base(u64 base) { gd->arch.tsc_base = base; @@ -34,17 +136,16 @@ u64 __attribute__((no_instrument_function)) get_ticks(void) return now_tick - gd->arch.tsc_base; } -#define PLATFORM_INFO_MSR 0xce - /* Get the speed of the TSC timer in MHz */ unsigned __attribute__((no_instrument_function)) long get_tbclk_mhz(void) { - u32 ratio; - u64 platform_info = native_read_msr(PLATFORM_INFO_MSR); + unsigned long fast_calibrate; + + fast_calibrate = try_msr_calibrate_tsc(); + if (!fast_calibrate) + panic("TSC frequency is ZERO"); - /* 100MHz times Max Non Turbo ratio */ - ratio = (platform_info >> 8) & 0xff; - return 100 * ratio; + return fast_calibrate; } unsigned long get_tbclk(void) |