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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * acpi_lpat.c - LPAT table processing functions4 *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 through14 * LPAT conversion table15 *16 * @lpat_table: the temperature_raw mapping table structure17 * @raw: the raw value, used as a key to get the temperature from the18 * above mapping table19 *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 through48 * LPAT conversion table49 *50 * @lpat_table: the temperature_raw mapping table51 * @temp: the temperature, used as a key to get the raw value from the52 * above mapping table53 *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 device83 *84 * Parse LPAT table to a struct of type acpi_lpat_table. On success85 * it returns a pointer to newly allocated table. This table must86 * be freed by the caller when finished processing, using a call to87 * acpi_lpat_free_conversion_table.88 */89struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(acpi_handle90 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 structure139 *140 * Frees the LPAT table previously allocated by a call to141 * acpi_lpat_get_conversion_table.142 */143void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table144 *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