1
2/*
3 * acpi_lpit.c - LPIT table processing functions
4 *
5 * Copyright (C) 2017 Intel Corporation. All rights reserved.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License version
9 * 2 as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 */
16
17#include <linux/cpu.h>
18#include <linux/acpi.h>
19#include <asm/msr.h>
20#include <asm/tsc.h>
21
22struct lpit_residency_info {
23 struct acpi_generic_address gaddr;
24 u64 frequency;
25 void __iomem *iomem_addr;
26};
27
28/* Storage for an memory mapped and FFH based entries */
29static struct lpit_residency_info residency_info_mem;
30static struct lpit_residency_info residency_info_ffh;
31
32static int lpit_read_residency_counter_us(u64 *counter, bool io_mem)
33{
34 int err;
35
36 if (io_mem) {
37 u64 count = 0;
38 int error;
39
40 error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count,
41 residency_info_mem.gaddr.bit_width);
42 if (error)
43 return error;
44
45 *counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency);
46 return 0;
47 }
48
49 err = rdmsrl_safe(residency_info_ffh.gaddr.address, counter);
50 if (!err) {
51 u64 mask = GENMASK_ULL(residency_info_ffh.gaddr.bit_offset +
52 residency_info_ffh.gaddr. bit_width - 1,
53 residency_info_ffh.gaddr.bit_offset);
54
55 *counter &= mask;
56 *counter >>= residency_info_ffh.gaddr.bit_offset;
57 *counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency);
58 return 0;
59 }
60
61 return -ENODATA;
62}
63
64static ssize_t low_power_idle_system_residency_us_show(struct device *dev,
65 struct device_attribute *attr,
66 char *buf)
67{
68 u64 counter;
69 int ret;
70
71 ret = lpit_read_residency_counter_us(&counter, true);
72 if (ret)
73 return ret;
74
75 return sprintf(buf, "%llu\n", counter);
76}
77static DEVICE_ATTR_RO(low_power_idle_system_residency_us);
78
79static ssize_t low_power_idle_cpu_residency_us_show(struct device *dev,
80 struct device_attribute *attr,
81 char *buf)
82{
83 u64 counter;
84 int ret;
85
86 ret = lpit_read_residency_counter_us(&counter, false);
87 if (ret)
88 return ret;
89
90 return sprintf(buf, "%llu\n", counter);
91}
92static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us);
93
94int lpit_read_residency_count_address(u64 *address)
95{
96 if (!residency_info_mem.gaddr.address)
97 return -EINVAL;
98
99 *address = residency_info_mem.gaddr.address;
100
101 return 0;
102}
103EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
104
105static void lpit_update_residency(struct lpit_residency_info *info,
106 struct acpi_lpit_native *lpit_native)
107{
108 info->frequency = lpit_native->counter_frequency ?
109 lpit_native->counter_frequency : tsc_khz * 1000;
110 if (!info->frequency)
111 info->frequency = 1;
112
113 info->gaddr = lpit_native->residency_counter;
114 if (info->gaddr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
115 info->iomem_addr = ioremap_nocache(info->gaddr.address,
116 info->gaddr.bit_width / 8);
117 if (!info->iomem_addr)
118 return;
119
120 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
121 return;
122
123 /* Silently fail, if cpuidle attribute group is not present */
124 sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
125 &dev_attr_low_power_idle_system_residency_us.attr,
126 "cpuidle");
127 } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
128 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
129 return;
130
131 /* Silently fail, if cpuidle attribute group is not present */
132 sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
133 &dev_attr_low_power_idle_cpu_residency_us.attr,
134 "cpuidle");
135 }
136}
137
138static void lpit_process(u64 begin, u64 end)
139{
140 while (begin + sizeof(struct acpi_lpit_native) < end) {
141 struct acpi_lpit_native *lpit_native = (struct acpi_lpit_native *)begin;
142
143 if (!lpit_native->header.type && !lpit_native->header.flags) {
144 if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
145 !residency_info_mem.gaddr.address) {
146 lpit_update_residency(&residency_info_mem, lpit_native);
147 } else if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
148 !residency_info_ffh.gaddr.address) {
149 lpit_update_residency(&residency_info_ffh, lpit_native);
150 }
151 }
152 begin += lpit_native->header.length;
153 }
154}
155
156void acpi_init_lpit(void)
157{
158 acpi_status status;
159 u64 lpit_begin;
160 struct acpi_table_lpit *lpit;
161
162 status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
163
164 if (ACPI_FAILURE(status))
165 return;
166
167 lpit_begin = (u64)lpit + sizeof(*lpit);
168 lpit_process(lpit_begin, lpit_begin + lpit->header.length);
169}
170