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/*
* acpi_lpit.c - LPIT table processing functions
*
* Copyright (C) 2017 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#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_nocache(info->gaddr.address,
info->gaddr.bit_width / 8);
if (!info->iomem_addr)
return;
if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
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) {
if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
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_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;
u64 lpit_begin;
struct acpi_table_lpit *lpit;
status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
if (ACPI_FAILURE(status))
return;
lpit_begin = (u64)lpit + sizeof(*lpit);
lpit_process(lpit_begin, lpit_begin + lpit->header.length);
}
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