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); 152