LXR linux/drivers/acpi/acpi

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * acpi_lpat.c - LPAT table processing functions
   4 *
   5 * Copyright (C) 2015 Intel Corporation. All rights reserved.
   6 */
   7
   8#include <linux/export.h>
   9#include <linux/acpi.h>
  10#include <acpi/acpi_lpat.h>
  11
  12/**
  13 * acpi_lpat_raw_to_temp(): Return temperature from raw value through
  14 * LPAT conversion table
  15 *
  16 * @lpat_table: the temperature_raw mapping table structure
  17 * @raw: the raw value, used as a key to get the temperature from the
  18 *       above mapping table
  19 *
  20 * A positive converted temperature value will be returned on success,
  21 * a negative errno will be returned in error cases.
  22 */
  23int acpi_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
  24                          int raw)
  25{
  26        int i, delta_temp, delta_raw, temp;
  27        struct acpi_lpat *lpat = lpat_table->lpat;
  28
  29        for (i = 0; i < lpat_table->lpat_count - 1; i++) {
  30                if ((raw >= lpat[i].raw && raw <= lpat[i+1].raw) ||
  31                    (raw <= lpat[i].raw && raw >= lpat[i+1].raw))
  32                        break;
  33        }
  34
  35        if (i == lpat_table->lpat_count - 1)
  36                return -ENOENT;
  37
  38        delta_temp = lpat[i+1].temp - lpat[i].temp;
  39        delta_raw = lpat[i+1].raw - lpat[i].raw;
  40        temp = lpat[i].temp + (raw - lpat[i].raw) * delta_temp / delta_raw;
  41
  42        return temp;
  43}
  44EXPORT_SYMBOL_GPL(acpi_lpat_raw_to_temp);
  45
  46/**
  47 * acpi_lpat_temp_to_raw(): Return raw value from temperature through
  48 * LPAT conversion table
  49 *
  50 * @lpat_table: the temperature_raw mapping table
  51 * @temp: the temperature, used as a key to get the raw value from the
  52 *        above mapping table
  53 *
  54 * The raw value will be returned on success,
  55 * a negative errno will be returned in error cases.
  56 */
  57int acpi_lpat_temp_to_raw(struct acpi_lpat_conversion_table *lpat_table,
  58                          int temp)
  59{
  60        int i, delta_temp, delta_raw, raw;
  61        struct acpi_lpat *lpat = lpat_table->lpat;
  62
  63        for (i = 0; i < lpat_table->lpat_count - 1; i++) {
  64                if (temp >= lpat[i].temp && temp <= lpat[i+1].temp)
  65                        break;
  66        }
  67
  68        if (i ==  lpat_table->lpat_count - 1)
  69                return -ENOENT;
  70
  71        delta_temp = lpat[i+1].temp - lpat[i].temp;
  72        delta_raw = lpat[i+1].raw - lpat[i].raw;
  73        raw = lpat[i].raw + (temp - lpat[i].temp) * delta_raw / delta_temp;
  74
  75        return raw;
  76}
  77EXPORT_SYMBOL_GPL(acpi_lpat_temp_to_raw);
  78
  79/**
  80 * acpi_lpat_get_conversion_table(): Parse ACPI LPAT table if present.
  81 *
  82 * @handle: Handle to acpi device
  83 *
  84 * Parse LPAT table to a struct of type acpi_lpat_table. On success
  85 * it returns a pointer to newly allocated table. This table must
  86 * be freed by the caller when finished processing, using a call to
  87 * acpi_lpat_free_conversion_table.
  88 */
  89struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(acpi_handle
  90                                                                  handle)
  91{
  92        struct acpi_lpat_conversion_table *lpat_table = NULL;
  93        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  94        union acpi_object *obj_p, *obj_e;
  95        int *lpat, i;
  96        acpi_status status;
  97
  98        status = acpi_evaluate_object(handle, "LPAT", NULL, &buffer);
  99        if (ACPI_FAILURE(status))
 100                return NULL;
 101
 102        obj_p = (union acpi_object *)buffer.pointer;
 103        if (!obj_p || (obj_p->type != ACPI_TYPE_PACKAGE) ||
 104            (obj_p->package.count % 2) || (obj_p->package.count < 4))
 105                goto out;
 106
 107        lpat = kcalloc(obj_p->package.count, sizeof(int), GFP_KERNEL);
 108        if (!lpat)
 109                goto out;
 110
 111        for (i = 0; i < obj_p->package.count; i++) {
 112                obj_e = &obj_p->package.elements[i];
 113                if (obj_e->type != ACPI_TYPE_INTEGER) {
 114                        kfree(lpat);
 115                        goto out;
 116                }
 117                lpat[i] = (s64)obj_e->integer.value;
 118        }
 119
 120        lpat_table = kzalloc(sizeof(*lpat_table), GFP_KERNEL);
 121        if (!lpat_table) {
 122                kfree(lpat);
 123                goto out;
 124        }
 125
 126        lpat_table->lpat = (struct acpi_lpat *)lpat;
 127        lpat_table->lpat_count = obj_p->package.count / 2;
 128
 129out:
 130        kfree(buffer.pointer);
 131        return lpat_table;
 132}
 133EXPORT_SYMBOL_GPL(acpi_lpat_get_conversion_table);
 134
 135/**
 136 * acpi_lpat_free_conversion_table(): Free LPAT table.
 137 *
 138 * @lpat_table: the temperature_raw mapping table structure
 139 *
 140 * Frees the LPAT table previously allocated by a call to
 141 * acpi_lpat_get_conversion_table.
 142 */
 143void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table
 144                                     *lpat_table)
 145{
 146        if (lpat_table) {
 147                kfree(lpat_table->lpat);
 148                kfree(lpat_table);
 149        }
 150}
 151EXPORT_SYMBOL_GPL(acpi_lpat_free_conversion_table);
 152