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![Rajneesh Bhardwaj](/assets/img/avatar_default.png)
ACPI Low Power S0 Idle capabilities are announced via FADT table and can be used to inform the kernel about the presence of one or more Low Power Idle (LPI) entries as descried in LPIT table. LPIT table can exist independently even if the FADT S0 Idle flag is not set and thus it could confuse user since the following cpuidle attributes are created. /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us /sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us Presence or absence of above attributes could mean that the given platform supports S0ix state or not. This change allows to create the above cpuidle attributes only if FADT table supports Low Power S0 Idle. Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
169 lines
4.6 KiB
C
169 lines
4.6 KiB
C
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/*
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* acpi_lpit.c - LPIT table processing functions
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*
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* Copyright (C) 2017 Intel Corporation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/cpu.h>
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#include <linux/acpi.h>
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#include <asm/msr.h>
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#include <asm/tsc.h>
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struct lpit_residency_info {
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struct acpi_generic_address gaddr;
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u64 frequency;
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void __iomem *iomem_addr;
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};
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/* Storage for an memory mapped and FFH based entries */
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static struct lpit_residency_info residency_info_mem;
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static struct lpit_residency_info residency_info_ffh;
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static int lpit_read_residency_counter_us(u64 *counter, bool io_mem)
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{
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int err;
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if (io_mem) {
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u64 count = 0;
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int error;
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error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count,
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residency_info_mem.gaddr.bit_width);
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if (error)
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return error;
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*counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency);
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return 0;
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}
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err = rdmsrl_safe(residency_info_ffh.gaddr.address, counter);
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if (!err) {
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u64 mask = GENMASK_ULL(residency_info_ffh.gaddr.bit_offset +
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residency_info_ffh.gaddr. bit_width - 1,
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residency_info_ffh.gaddr.bit_offset);
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*counter &= mask;
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*counter >>= residency_info_ffh.gaddr.bit_offset;
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*counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency);
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return 0;
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}
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return -ENODATA;
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}
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static ssize_t low_power_idle_system_residency_us_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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u64 counter;
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int ret;
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ret = lpit_read_residency_counter_us(&counter, true);
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if (ret)
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return ret;
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return sprintf(buf, "%llu\n", counter);
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}
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static DEVICE_ATTR_RO(low_power_idle_system_residency_us);
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static ssize_t low_power_idle_cpu_residency_us_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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u64 counter;
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int ret;
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ret = lpit_read_residency_counter_us(&counter, false);
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if (ret)
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return ret;
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return sprintf(buf, "%llu\n", counter);
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}
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static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us);
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int lpit_read_residency_count_address(u64 *address)
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{
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if (!residency_info_mem.gaddr.address)
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return -EINVAL;
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*address = residency_info_mem.gaddr.address;
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return 0;
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}
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EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
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static void lpit_update_residency(struct lpit_residency_info *info,
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struct acpi_lpit_native *lpit_native)
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{
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info->frequency = lpit_native->counter_frequency ?
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lpit_native->counter_frequency : tsc_khz * 1000;
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if (!info->frequency)
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info->frequency = 1;
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info->gaddr = lpit_native->residency_counter;
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if (info->gaddr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
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info->iomem_addr = ioremap_nocache(info->gaddr.address,
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info->gaddr.bit_width / 8);
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if (!info->iomem_addr)
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return;
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if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
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return;
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/* Silently fail, if cpuidle attribute group is not present */
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sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
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&dev_attr_low_power_idle_system_residency_us.attr,
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"cpuidle");
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} else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
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if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
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return;
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/* Silently fail, if cpuidle attribute group is not present */
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sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
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&dev_attr_low_power_idle_cpu_residency_us.attr,
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"cpuidle");
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}
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}
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static void lpit_process(u64 begin, u64 end)
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{
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while (begin + sizeof(struct acpi_lpit_native) < end) {
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struct acpi_lpit_native *lpit_native = (struct acpi_lpit_native *)begin;
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if (!lpit_native->header.type && !lpit_native->header.flags) {
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if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
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!residency_info_mem.gaddr.address) {
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lpit_update_residency(&residency_info_mem, lpit_native);
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} else if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
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!residency_info_ffh.gaddr.address) {
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lpit_update_residency(&residency_info_ffh, lpit_native);
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}
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}
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begin += lpit_native->header.length;
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}
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}
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void acpi_init_lpit(void)
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{
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acpi_status status;
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u64 lpit_begin;
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struct acpi_table_lpit *lpit;
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status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
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if (ACPI_FAILURE(status))
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return;
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lpit_begin = (u64)lpit + sizeof(*lpit);
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lpit_process(lpit_begin, lpit_begin + lpit->header.length);
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}
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