diff options
Diffstat (limited to 'src/soc/amd/stoneyridge/tsc_freq.c')
| -rw-r--r-- | src/soc/amd/stoneyridge/tsc_freq.c | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/src/soc/amd/stoneyridge/tsc_freq.c b/src/soc/amd/stoneyridge/tsc_freq.c new file mode 100644 index 0000000000..1f48306afe --- /dev/null +++ b/src/soc/amd/stoneyridge/tsc_freq.c @@ -0,0 +1,49 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2015 Intel Corp. + * Copyright (C) 2017 Advanced Micro Devices + * + * 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 + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <arch/io.h> +#include <cpu/x86/msr.h> +#include <cpu/x86/tsc.h> +#include <cpu/amd/amdfam15.h> +#include <console/console.h> +#include <soc/pci_devs.h> + +unsigned long tsc_freq_mhz(void) +{ + msr_t msr; + uint8_t cpufid; + uint8_t cpudid; + uint8_t boost_states; + + /* + * See the Family 15h Models 70h-7Fh BKDG (PID 55072) definition for + * MSR0000_0010. The TSC increments at the P0 frequency. According + * to the "Software P-state Numbering" section, P0 is the highest + * non-boosted state. freq = 100MHz * (CpuFid + 10h) / (2^(CpuDid)). + */ + boost_states = (pci_read_config32(DEV_D18F4, CORE_PERF_BOOST_CTRL) + >> 2) & 0x7; + + msr = rdmsr(PSTATE_0_MSR + boost_states); + if (!(msr.hi & 0x80000000)) + die("Unknown error: cannot determine P-state 0\n"); + + cpufid = (msr.lo & 0x3f); + cpudid = (msr.lo & 0x1c0) >> 6; + + return (100 * (cpufid + 0x10)) / (0x01 << cpudid); +} |