1 // SPDX-License-Identifier: GPL-2.0-only
4 * acpi_lpit.c - LPIT table processing functions
6 * Copyright (C) 2017 Intel Corporation. All rights reserved.
10 #include <linux/acpi.h>
14 struct lpit_residency_info {
15 struct acpi_generic_address gaddr;
17 void __iomem *iomem_addr;
20 /* Storage for an memory mapped and FFH based entries */
21 static struct lpit_residency_info residency_info_mem;
22 static struct lpit_residency_info residency_info_ffh;
24 static int lpit_read_residency_counter_us(u64 *counter, bool io_mem)
32 error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count,
33 residency_info_mem.gaddr.bit_width);
37 *counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency);
41 err = rdmsrl_safe(residency_info_ffh.gaddr.address, counter);
43 u64 mask = GENMASK_ULL(residency_info_ffh.gaddr.bit_offset +
44 residency_info_ffh.gaddr. bit_width - 1,
45 residency_info_ffh.gaddr.bit_offset);
48 *counter >>= residency_info_ffh.gaddr.bit_offset;
49 *counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency);
56 static ssize_t low_power_idle_system_residency_us_show(struct device *dev,
57 struct device_attribute *attr,
63 ret = lpit_read_residency_counter_us(&counter, true);
67 return sprintf(buf, "%llu\n", counter);
69 static DEVICE_ATTR_RO(low_power_idle_system_residency_us);
71 static ssize_t low_power_idle_cpu_residency_us_show(struct device *dev,
72 struct device_attribute *attr,
78 ret = lpit_read_residency_counter_us(&counter, false);
82 return sprintf(buf, "%llu\n", counter);
84 static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us);
86 int lpit_read_residency_count_address(u64 *address)
88 if (!residency_info_mem.gaddr.address)
91 *address = residency_info_mem.gaddr.address;
95 EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
97 static void lpit_update_residency(struct lpit_residency_info *info,
98 struct acpi_lpit_native *lpit_native)
100 info->frequency = lpit_native->counter_frequency ?
101 lpit_native->counter_frequency : tsc_khz * 1000;
102 if (!info->frequency)
105 info->gaddr = lpit_native->residency_counter;
106 if (info->gaddr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
107 info->iomem_addr = ioremap(info->gaddr.address,
108 info->gaddr.bit_width / 8);
109 if (!info->iomem_addr)
112 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
115 /* Silently fail, if cpuidle attribute group is not present */
116 sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
117 &dev_attr_low_power_idle_system_residency_us.attr,
119 } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
120 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
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_cpu_residency_us.attr,
130 static void lpit_process(u64 begin, u64 end)
132 while (begin + sizeof(struct acpi_lpit_native) <= end) {
133 struct acpi_lpit_native *lpit_native = (struct acpi_lpit_native *)begin;
135 if (!lpit_native->header.type && !lpit_native->header.flags) {
136 if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
137 !residency_info_mem.gaddr.address) {
138 lpit_update_residency(&residency_info_mem, lpit_native);
139 } else if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
140 !residency_info_ffh.gaddr.address) {
141 lpit_update_residency(&residency_info_ffh, lpit_native);
144 begin += lpit_native->header.length;
148 void acpi_init_lpit(void)
151 struct acpi_table_lpit *lpit;
153 status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
154 if (ACPI_FAILURE(status))
157 lpit_process((u64)lpit + sizeof(*lpit),
158 (u64)lpit + lpit->header.length);
160 acpi_put_table((struct acpi_table_header *)lpit);