--- /dev/null
+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
+
+Residencies for each low power state can be read via FFH
+(Function fixed hardware) or a memory mapped interface.
+
+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)
+
+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
+
+The "low_power_idle_cpu_residency_us" attribute shows time spent
+by the CPU package in PKG C10
+
+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.
--- /dev/null
+
+/*
+ * 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;
+}
+
+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;
+
+ /* 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;
+ 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);
+}
EXPORT_SYMBOL(acpi_os_write_port);
+int acpi_os_read_iomem(void __iomem *virt_addr, u64 *value, u32 width)
+{
+
+ switch (width) {
+ case 8:
+ *(u8 *) value = readb(virt_addr);
+ break;
+ case 16:
+ *(u16 *) value = readw(virt_addr);
+ break;
+ case 32:
+ *(u32 *) value = readl(virt_addr);
+ break;
+ case 64:
+ *(u64 *) value = readq(virt_addr);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
acpi_status
acpi_os_read_memory(acpi_physical_address phys_addr, u64 *value, u32 width)
{
unsigned int size = width / 8;
bool unmap = false;
u64 dummy;
+ int error;
rcu_read_lock();
virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
if (!value)
value = &dummy;
- switch (width) {
- case 8:
- *(u8 *) value = readb(virt_addr);
- break;
- case 16:
- *(u16 *) value = readw(virt_addr);
- break;
- case 32:
- *(u32 *) value = readl(virt_addr);
- break;
- case 64:
- *(u64 *) value = readq(virt_addr);
- break;
- default:
- BUG();
- }
+ error = acpi_os_read_iomem(virt_addr, value, width);
+ BUG_ON(error);
if (unmap)
iounmap(virt_addr);
projects / users / hch / configfs.git / commitdiff