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linux/drivers/acpi/acpi_lpit.c
Rafael J. Wysocki 403dbe3a53 Revert "ACPI / PM: LPIT: Register sysfs attributes based on FADT"
Revert commit 1cdda9486f ("ACPI / PM: LPIT: Register sysfs attributes
based on FADT"), because what it did was more confusing than it would
be to allow the sysfs attributes in question to be created regardless
of whether or not the relevant flag was set in the FADT.

If ACPI_FADT_LOW_POWER_S0 is not set, it need not mean that LPIT is
invalid and low-power S0 idle is not usable.  It merely means that
using S3 on the given system is more beneficial from the energy
saving perspective than using low-power S0 idle.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
2022-07-15 20:04:07 +02:00

156 lines
4.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* acpi_lpit.c - LPIT table processing functions
*
* Copyright (C) 2017 Intel Corporation. All rights reserved.
*/
#include <linux/cpu.h>
#include <linux/acpi.h>
#include <asm/msr.h>
#include <asm/tsc.h>
struct lpit_residency_info {
struct acpi_generic_address gaddr;
u64 frequency;
void __iomem *iomem_addr;
};
/* Storage for an memory mapped and FFH based entries */
static struct lpit_residency_info residency_info_mem;
static struct lpit_residency_info residency_info_ffh;
static int lpit_read_residency_counter_us(u64 *counter, bool io_mem)
{
int err;
if (io_mem) {
u64 count = 0;
int error;
error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count,
residency_info_mem.gaddr.bit_width);
if (error)
return error;
*counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency);
return 0;
}
err = rdmsrl_safe(residency_info_ffh.gaddr.address, counter);
if (!err) {
u64 mask = GENMASK_ULL(residency_info_ffh.gaddr.bit_offset +
residency_info_ffh.gaddr. bit_width - 1,
residency_info_ffh.gaddr.bit_offset);
*counter &= mask;
*counter >>= residency_info_ffh.gaddr.bit_offset;
*counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency);
return 0;
}
return -ENODATA;
}
static ssize_t low_power_idle_system_residency_us_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
u64 counter;
int ret;
ret = lpit_read_residency_counter_us(&counter, true);
if (ret)
return ret;
return sprintf(buf, "%llu\n", counter);
}
static DEVICE_ATTR_RO(low_power_idle_system_residency_us);
static ssize_t low_power_idle_cpu_residency_us_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
u64 counter;
int ret;
ret = lpit_read_residency_counter_us(&counter, false);
if (ret)
return ret;
return sprintf(buf, "%llu\n", counter);
}
static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us);
int lpit_read_residency_count_address(u64 *address)
{
if (!residency_info_mem.gaddr.address)
return -EINVAL;
*address = residency_info_mem.gaddr.address;
return 0;
}
EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
static void lpit_update_residency(struct lpit_residency_info *info,
struct acpi_lpit_native *lpit_native)
{
info->frequency = lpit_native->counter_frequency ?
lpit_native->counter_frequency : tsc_khz * 1000;
if (!info->frequency)
info->frequency = 1;
info->gaddr = lpit_native->residency_counter;
if (info->gaddr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
info->iomem_addr = ioremap(info->gaddr.address,
info->gaddr.bit_width / 8);
if (!info->iomem_addr)
return;
/* Silently fail, if cpuidle attribute group is not present */
sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
&dev_attr_low_power_idle_system_residency_us.attr,
"cpuidle");
} else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
/* Silently fail, if cpuidle attribute group is not present */
sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
&dev_attr_low_power_idle_cpu_residency_us.attr,
"cpuidle");
}
}
static void lpit_process(u64 begin, u64 end)
{
while (begin + sizeof(struct acpi_lpit_native) <= end) {
struct acpi_lpit_native *lpit_native = (struct acpi_lpit_native *)begin;
if (!lpit_native->header.type && !lpit_native->header.flags) {
if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
!residency_info_mem.gaddr.address) {
lpit_update_residency(&residency_info_mem, lpit_native);
} else if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
!residency_info_ffh.gaddr.address) {
lpit_update_residency(&residency_info_ffh, lpit_native);
}
}
begin += lpit_native->header.length;
}
}
void acpi_init_lpit(void)
{
acpi_status status;
struct acpi_table_lpit *lpit;
status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
if (ACPI_FAILURE(status))
return;
lpit_process((u64)lpit + sizeof(*lpit),
(u64)lpit + lpit->header.length);
acpi_put_table((struct acpi_table_header *)lpit);
}