drivers/acpi/acpi_lpit.c

   1
   2 /*
   3  * acpi_lpit.c - LPIT table processing functions
   4  *
   5  * Copyright (C) 2017 Intel Corporation. All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License version
   9  * 2 as published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/cpu.h>
  18 #include <linux/acpi.h>
  19 #include <asm/msr.h>
  20 #include <asm/tsc.h>
  21
  22 struct lpit_residency_info {
  23         struct acpi_generic_address gaddr;
  24         u64 frequency;
  25         void __iomem *iomem_addr;
  26 };
  27
  28 /* Storage for an memory mapped and FFH based entries */
  29 static struct lpit_residency_info residency_info_mem;
  30 static struct lpit_residency_info residency_info_ffh;
  31
  32 static int lpit_read_residency_counter_us(u64 *counter, bool io_mem)
  33 {
  34         int err;
  35
  36         if (io_mem) {
  37                 u64 count = 0;
  38                 int error;
  39
  40                 error = acpi_os_read_iomem(residency_info_mem.iomem_addr, &count,
  41                                            residency_info_mem.gaddr.bit_width);
  42                 if (error)
  43                         return error;
  44
  45                 *counter = div64_u64(count * 1000000ULL, residency_info_mem.frequency);
  46                 return 0;
  47         }
  48
  49         err = rdmsrl_safe(residency_info_ffh.gaddr.address, counter);
  50         if (!err) {
  51                 u64 mask = GENMASK_ULL(residency_info_ffh.gaddr.bit_offset +
  52                                        residency_info_ffh.gaddr. bit_width - 1,
  53                                        residency_info_ffh.gaddr.bit_offset);
  54
  55                 *counter &= mask;
  56                 *counter >>= residency_info_ffh.gaddr.bit_offset;
  57                 *counter = div64_u64(*counter * 1000000ULL, residency_info_ffh.frequency);
  58                 return 0;
  59         }
  60
  61         return -ENODATA;
  62 }
  63
  64 static ssize_t low_power_idle_system_residency_us_show(struct device *dev,
  65                                                        struct device_attribute *attr,
  66                                                        char *buf)
  67 {
  68         u64 counter;
  69         int ret;
  70
  71         ret = lpit_read_residency_counter_us(&counter, true);
  72         if (ret)
  73                 return ret;
  74
  75         return sprintf(buf, "%llu\n", counter);
  76 }
  77 static DEVICE_ATTR_RO(low_power_idle_system_residency_us);
  78
  79 static ssize_t low_power_idle_cpu_residency_us_show(struct device *dev,
  80                                                     struct device_attribute *attr,
  81                                                     char *buf)
  82 {
  83         u64 counter;
  84         int ret;
  85
  86         ret = lpit_read_residency_counter_us(&counter, false);
  87         if (ret)
  88                 return ret;
  89
  90         return sprintf(buf, "%llu\n", counter);
  91 }
  92 static DEVICE_ATTR_RO(low_power_idle_cpu_residency_us);
  93
  94 int lpit_read_residency_count_address(u64 *address)
  95 {
  96         if (!residency_info_mem.gaddr.address)
  97                 return -EINVAL;
  98
  99         *address = residency_info_mem.gaddr.address;
 100
 101         return 0;
 102 }
 103 EXPORT_SYMBOL_GPL(lpit_read_residency_count_address);
 104
 105 static void lpit_update_residency(struct lpit_residency_info *info,
 106                                  struct acpi_lpit_native *lpit_native)
 107 {
 108         info->frequency = lpit_native->counter_frequency ?
 109                                 lpit_native->counter_frequency : tsc_khz * 1000;
 110         if (!info->frequency)
 111                 info->frequency = 1;
 112
 113         info->gaddr = lpit_native->residency_counter;
 114         if (info->gaddr.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
 115                 info->iomem_addr = ioremap_nocache(info->gaddr.address,
 116                                                    info->gaddr.bit_width / 8);
 117                 if (!info->iomem_addr)
 118                         return;
 119
 120                 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
 121                         return;
 122
 123                 /* Silently fail, if cpuidle attribute group is not present */
 124                 sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
 125                                         &dev_attr_low_power_idle_system_residency_us.attr,
 126                                         "cpuidle");
 127         } else if (info->gaddr.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
 128                 if (!(acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0))
 129                         return;
 130
 131                 /* Silently fail, if cpuidle attribute group is not present */
 132                 sysfs_add_file_to_group(&cpu_subsys.dev_root->kobj,
 133                                         &dev_attr_low_power_idle_cpu_residency_us.attr,
 134                                         "cpuidle");
 135         }
 136 }
 137
 138 static void lpit_process(u64 begin, u64 end)
 139 {
 140         while (begin + sizeof(struct acpi_lpit_native) < end) {
 141                 struct acpi_lpit_native *lpit_native = (struct acpi_lpit_native *)begin;
 142
 143                 if (!lpit_native->header.type && !lpit_native->header.flags) {
 144                         if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
 145                             !residency_info_mem.gaddr.address) {
 146                                 lpit_update_residency(&residency_info_mem, lpit_native);
 147                         } else if (lpit_native->residency_counter.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
 148                                    !residency_info_ffh.gaddr.address) {
 149                                 lpit_update_residency(&residency_info_ffh, lpit_native);
 150                         }
 151                 }
 152                 begin += lpit_native->header.length;
 153         }
 154 }
 155
 156 void acpi_init_lpit(void)
 157 {
 158         acpi_status status;
 159         u64 lpit_begin;
 160         struct acpi_table_lpit *lpit;
 161
 162         status = acpi_get_table(ACPI_SIG_LPIT, 0, (struct acpi_table_header **)&lpit);
 163
 164         if (ACPI_FAILURE(status))
 165                 return;
 166
 167         lpit_begin = (u64)lpit + sizeof(*lpit);
 168         lpit_process(lpit_begin, lpit_begin + lpit->header.length);
 169 }