drivers/acpi/acpi_lpat.c

   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  */
  23 int 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 }
  44 EXPORT_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  */
  57 int 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 }
  77 EXPORT_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  */
  89 struct 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
 129 out:
 130         kfree(buffer.pointer);
 131         return lpat_table;
 132 }
 133 EXPORT_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  */
 143 void 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 }
 151 EXPORT_SYMBOL_GPL(acpi_lpat_free_conversion_table);