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| Original file line number | Diff line number | Diff line change |
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| To enumerate platform Low Power Idle states, Intel platforms are using | ||
| “Low Power Idle Table” (LPIT). More details about this table can be | ||
| downloaded from: | ||
| http://www.uefi.org/sites/default/files/resources/Intel_ACPI_Low_Power_S0_Idle.pdf | ||
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| Residencies for each low power state can be read via FFH | ||
| (Function fixed hardware) or a memory mapped interface. | ||
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| On platforms supporting S0ix sleep states, there can be two types of | ||
| residencies: | ||
| - CPU PKG C10 (Read via FFH interface) | ||
| - Platform Controller Hub (PCH) SLP_S0 (Read via memory mapped interface) | ||
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| The following attributes are added dynamically to the cpuidle | ||
| sysfs attribute group: | ||
| /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us | ||
| /sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us | ||
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| The "low_power_idle_cpu_residency_us" attribute shows time spent | ||
| by the CPU package in PKG C10 | ||
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| The "low_power_idle_system_residency_us" attribute shows SLP_S0 | ||
| residency, or system time spent with the SLP_S0# signal asserted. | ||
| This is the lowest possible system power state, achieved only when CPU is in | ||
| PKG C10 and all functional blocks in PCH are in a low power state. |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,162 @@ | ||
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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. | ||
| */ | ||
|
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| #include <linux/cpu.h> | ||
| #include <linux/acpi.h> | ||
| #include <asm/msr.h> | ||
| #include <asm/tsc.h> | ||
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| struct lpit_residency_info { | ||
| struct acpi_generic_address gaddr; | ||
| u64 frequency; | ||
| void __iomem *iomem_addr; | ||
| }; | ||
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| /* 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; | ||
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| static int lpit_read_residency_counter_us(u64 *counter, bool io_mem) | ||
| { | ||
| int err; | ||
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| if (io_mem) { | ||
| u64 count = 0; | ||
| int error; | ||
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| error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count, | ||
| residency_info_mem.gaddr.bit_width); | ||
| if (error) | ||
| return error; | ||
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| *counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency); | ||
| return 0; | ||
| } | ||
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| 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); | ||
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| *counter &= mask; | ||
| *counter >>= residency_info_ffh.gaddr.bit_offset; | ||
| *counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency); | ||
| return 0; | ||
| } | ||
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| return -ENODATA; | ||
| } | ||
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| static ssize_t low_power_idle_system_residency_us_show(struct device *dev, | ||
| struct device_attribute *attr, | ||
| char *buf) | ||
| { | ||
| u64 counter; | ||
| int ret; | ||
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| ret = lpit_read_residency_counter_us(&counter, true); | ||
| if (ret) | ||
| return ret; | ||
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| return sprintf(buf, "%llu\n", counter); | ||
| } | ||
| 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, | ||
| struct device_attribute *attr, | ||
| char *buf) | ||
| { | ||
| u64 counter; | ||
| int ret; | ||
|
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| ret = lpit_read_residency_counter_us(&counter, false); | ||
| if (ret) | ||
| return ret; | ||
|
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| return sprintf(buf, "%llu\n", counter); | ||
| } | ||
| static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us); | ||
|
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| int lpit_read_residency_count_address(u64 *address) | ||
| { | ||
| if (!residency_info_mem.gaddr.address) | ||
| return -EINVAL; | ||
|
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| *address = residency_info_mem.gaddr.address; | ||
|
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| return 0; | ||
| } | ||
|
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| 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; | ||
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| 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; | ||
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| /* 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"); | ||
| } | ||
| } | ||
|
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| 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; | ||
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| 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; | ||
| } | ||
| } | ||
|
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| void acpi_init_lpit(void) | ||
| { | ||
| acpi_status status; | ||
| u64 lpit_begin; | ||
| 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)) | ||
| return; | ||
|
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| lpit_begin = (u64)lpit + sizeof(*lpit); | ||
| lpit_process(lpit_begin, lpit_begin + lpit->header.length); | ||
| } |
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