arch/x86/kernel/acpi/cppc_msr.c

   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
  12 bool cpc_ffh_supported(void)
  13 {
  14         return true;
  15 }
  16
  17 int 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
  32 int 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 }