diff options
| -rw-r--r-- | src/soc/intel/common/block/cpu/cpulib.c | 20 | ||||
| -rw-r--r-- | src/soc/intel/common/block/include/intelblocks/cpulib.h | 8 |
2 files changed, 28 insertions, 0 deletions
diff --git a/src/soc/intel/common/block/cpu/cpulib.c b/src/soc/intel/common/block/cpu/cpulib.c index 0c042df8b2..f2142d93cc 100644 --- a/src/soc/intel/common/block/cpu/cpulib.c +++ b/src/soc/intel/common/block/cpu/cpulib.c @@ -3,6 +3,7 @@ * * Copyright (C) 2014 Google Inc. * Copyright (C) 2015-2018 Intel Corporation. + * Copyright (C) 2018 Siemens AG * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -141,6 +142,25 @@ void cpu_set_p_state_to_max_non_turbo_ratio(void) } /* + * Set PERF_CTL MSR (0x199) P_Req (14:8 bits) with the value + * for maximum efficiency. This value is reported in PLATFORM_INFO MSR (0xCE) + * in Bits 47:40 and is extracted with cpu_get_min_ratio(). + */ +void cpu_set_p_state_to_min_clock_ratio(void) +{ + uint32_t min_ratio; + msr_t perf_ctl; + + /* Read the minimum ratio for the best efficiency. */ + min_ratio = cpu_get_min_ratio(); + perf_ctl.lo = (min_ratio << 8) & 0xff00; + perf_ctl.hi = 0; + wrmsr(IA32_PERF_CTL, perf_ctl); + printk(BIOS_DEBUG, "CPU: frequency set to %u MHz\n", + (min_ratio * CONFIG_CPU_BCLK_MHZ)); +} + +/* * Get the Burst/Turbo Mode State from MSR IA32_MISC_ENABLE 0x1A0 * Bit 38 - TURBO_MODE_DISABLE Bit to get state ENABLED / DISABLED. * Also check for the cpuid 0x6 to check whether Burst mode unsupported. diff --git a/src/soc/intel/common/block/include/intelblocks/cpulib.h b/src/soc/intel/common/block/include/intelblocks/cpulib.h index 88f04b439a..0d51146752 100644 --- a/src/soc/intel/common/block/include/intelblocks/cpulib.h +++ b/src/soc/intel/common/block/include/intelblocks/cpulib.h @@ -2,6 +2,7 @@ * This file is part of the coreboot project. * * Copyright (C) 2017 Intel Corporation. + * Copyright (C) 2018 Siemens AG * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -73,6 +74,13 @@ void cpu_set_p_state_to_nominal_tdp_ratio(void); void cpu_set_p_state_to_max_non_turbo_ratio(void); /* + * Set PERF_CTL MSR (0x199) P_Req (14:8 bits) with the value + * for maximum efficiency. This value is reported in PLATFORM_INFO MSR (0xCE) + * in Bits 47:40 and is extracted with cpu_get_min_ratio(). + */ +void cpu_set_p_state_to_min_clock_ratio(void); + +/* * Get the Burst/Turbo Mode State from MSR IA32_MISC_ENABLE 0x1A0 * Bit 38 - TURBO_MODE_DISABLE Bit to get state ENABLED / DISABLED. * Also check for the cpuid 0x6 to check whether Burst mode unsupported. |