1// SPDX-License-Identifier: GPL-2.0-only
  2
  3/*
  4 * acpi_lpit.c - LPIT table processing functions
  5 *
  6 * Copyright (C) 2017 Intel Corporation. All rights reserved.
  7 */
  8
  9#include <linux/cpu.h>
 10#include <linux/acpi.h>
 11#include <asm/msr.h>
 12#include <asm/tsc.h>
 13
 14struct lpit_residency_info {
 15	struct acpi_generic_address gaddr;
 16	u64 frequency;
 17	void __iomem *iomem_addr;
 18};
 19
 20/* Storage for an memory mapped and FFH based entries */
 21static struct lpit_residency_info residency_info_mem;
 22static struct lpit_residency_info residency_info_ffh;
 23
 24static int lpit_read_residency_counter_us(u64 *counter, bool io_mem)
 25{
 26	int err;
 27
 28	if (io_mem) {
 29		u64 count = 0;
 30		int error;
 31
 32		error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count,
 33					   residency_info_mem.gaddr.bit_width);
 34		if (error)
 35			return error;
 36
 37		*counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency);
 38		return 0;
 39	}
 40
 41	err = rdmsrl_safe(residency_info_ffh.gaddr.address, counter);
 42	if (!err) {
 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);
 46
 47		*counter &= mask;
 48		*counter >>= residency_info_ffh.gaddr.bit_offset;
 49		*counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency);
 50		return 0;
 51	}
 52
 53	return -ENODATA;
 54}
 55
 56static ssize_t low_power_idle_system_residency_us_show(struct device *dev,
 57						       struct device_attribute *attr,
 58						       char *buf)
 59{
 60	u64 counter;
 61	int ret;
 62
 63	ret = lpit_read_residency_counter_us(&counter, true);
 64	if (ret)
 65		return ret;
 66
 67	return sprintf(buf, "%llu\n", counter);
 68}
 69static DEVICE_ATTR_RO(low_power_idle_system_residency_us);
 70
 71static ssize_t low_power_idle_cpu_residency_us_show(struct device *dev,
 72						    struct device_attribute *attr,
 73						    char *buf)
 74{
 75	u64 counter;
 76	int ret;
 77
 78	ret = lpit_read_residency_counter_us(&counter, false);
 79	if (ret)
 80		return ret;
 81
 82	return sprintf(buf, "%llu\n", counter);
 83}
 84static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us);
 85
 86int lpit_read_residency_count_address(u64 *address)
 87{
 88	if (!residency_info_mem.gaddr.address)
 89		return -EINVAL;
 90
 91	*address = residency_info_mem.gaddr.address;
 92
 93	return 0;
 94}
 95EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
 96
 97static void lpit_update_residency(struct lpit_residency_info *info,
 98				 struct acpi_lpit_native *lpit_native)
 99{
100	info->frequency = lpit_native->counter_frequency ?
101				lpit_native->counter_frequency : tsc_khz * 1000;
102	if (!info->frequency)
103		info->frequency = 1;
104
105	info->gaddr = lpit_native->residency_counter;
106	if (info->gaddr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
107		info->iomem_addr = ioremap_nocache(info->gaddr.address,
108						   info->gaddr.bit_width / 8);
109		if (!info->iomem_addr)
110			return;
111
112		if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
113			return;
114
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,
118					"cpuidle");
119	} else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
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_cpu_residency_us.attr,
126					"cpuidle");
127	}
128}
129
130static void lpit_process(u64 begin, u64 end)
131{
132	while (begin + sizeof(struct acpi_lpit_native) <= end) {
133		struct acpi_lpit_native *lpit_native = (struct acpi_lpit_native *)begin;
134
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);
142			}
143		}
144		begin += lpit_native->header.length;
145	}
146}
147
148void acpi_init_lpit(void)
149{
150	acpi_status status;
151	struct acpi_table_lpit *lpit;
152
153	status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
154
155	if (ACPI_FAILURE(status))
156		return;
157
158	lpit_process((u64)lpit + sizeof(*lpit),
159		     (u64)lpit + lpit->header.length);
160}