1 /*
2 * cppc_msr.c: MSR Interface for CPPC
3 * Copyright (c) 2016, Intel Corporation.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 */
15
16 #include <acpi/cppc_acpi.h>
17 #include <asm/msr.h>
18
19 /* Refer to drivers/acpi/cppc_acpi.c for the description of functions */
20
cpc_ffh_supported(void)21 bool cpc_ffh_supported(void)
22 {
23 return true;
24 }
25
cpc_read_ffh(int cpunum,struct cpc_reg * reg,u64 * val)26 int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
27 {
28 int err;
29
30 err = rdmsrl_safe_on_cpu(cpunum, reg->address, val);
31 if (!err) {
32 u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
33 reg->bit_offset);
34
35 *val &= mask;
36 *val >>= reg->bit_offset;
37 }
38 return err;
39 }
40
cpc_write_ffh(int cpunum,struct cpc_reg * reg,u64 val)41 int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
42 {
43 u64 rd_val;
44 int err;
45
46 err = rdmsrl_safe_on_cpu(cpunum, reg->address, &rd_val);
47 if (!err) {
48 u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
49 reg->bit_offset);
50
51 val <<= reg->bit_offset;
52 val &= mask;
53 rd_val &= ~mask;
54 rd_val |= val;
55 err = wrmsrl_safe_on_cpu(cpunum, reg->address, rd_val);
56 }
57 return err;
58 }
59
