Quelle  acpi_lpit.c   Sprache: 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>
#include "internal.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 = rdmsrq_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)
{
 struct device *dev_root = bus_get_dev_root(&cpu_subsys);

 /* Silently fail, if cpuidle attribute group is not present */
 if (!dev_root)
  return;

 info->frequency = lpit_native->counter_frequency ?
    lpit_native->counter_frequency : mul_u32_u32(tsc_khz, 1000U);
 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)
   goto exit;

  sysfs_add_file_to_group(&dev_root->kobj,
     &dev_attr_low_power_idle_system_residency_us.attr,
     "cpuidle");
 } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
  sysfs_add_file_to_group(&dev_root->kobj,
     &dev_attr_low_power_idle_cpu_residency_us.attr,
     "cpuidle");
 }
exit:
 put_device(dev_root);
}

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);
}