linux/arch/x86/kernel/acpi/cppc_msr.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * cppc_msr.c:  MSR Interface for CPPC
   4 * Copyright (c) 2016, Intel Corporation.
   5 */
   6
   7#include <acpi/cppc_acpi.h>
   8#include <asm/msr.h>
   9
  10/* Refer to drivers/acpi/cppc_acpi.c for the description of functions */
  11
  12bool cpc_ffh_supported(void)
  13{
  14        return true;
  15}
  16
  17int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
  18{
  19        int err;
  20
  21        err = rdmsrl_safe_on_cpu(cpunum, reg->address, val);
  22        if (!err) {
  23                u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
  24                                       reg->bit_offset);
  25
  26                *val &= mask;
  27                *val >>= reg->bit_offset;
  28        }
  29        return err;
  30}
  31
  32int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
  33{
  34        u64 rd_val;
  35        int err;
  36
  37        err = rdmsrl_safe_on_cpu(cpunum, reg->address, &rd_val);
  38        if (!err) {
  39                u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
  40                                       reg->bit_offset);
  41
  42                val <<= reg->bit_offset;
  43                val &= mask;
  44                rd_val &= ~mask;
  45                rd_val |= val;
  46                err = wrmsrl_safe_on_cpu(cpunum, reg->address, rd_val);
  47        }
  48        return err;
  49}
  50