1/*
2 * acpi_lpat.c - LPAT table processing functions
3 *
4 * Copyright (C) 2015 Intel Corporation. All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version
8 * 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 */
15
16#include <linux/export.h>
17#include <linux/acpi.h>
18#include <acpi/acpi_lpat.h>
19
20/**
21 * acpi_lpat_raw_to_temp(): Return temperature from raw value through
22 * LPAT conversion table
23 *
24 * @lpat_table: the temperature_raw mapping table structure
25 * @raw: the raw value, used as a key to get the temerature from the
26 * above mapping table
27 *
28 * A positive converted temperature value will be returned on success,
29 * a negative errno will be returned in error cases.
30 */
31int acpi_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
32 int raw)
33{
34 int i, delta_temp, delta_raw, temp;
35 struct acpi_lpat *lpat = lpat_table->lpat;
36
37 for (i = 0; i < lpat_table->lpat_count - 1; i++) {
38 if ((raw >= lpat[i].raw && raw <= lpat[i+1].raw) ||
39 (raw <= lpat[i].raw && raw >= lpat[i+1].raw))
40 break;
41 }
42
43 if (i == lpat_table->lpat_count - 1)
44 return -ENOENT;
45
46 delta_temp = lpat[i+1].temp - lpat[i].temp;
47 delta_raw = lpat[i+1].raw - lpat[i].raw;
48 temp = lpat[i].temp + (raw - lpat[i].raw) * delta_temp / delta_raw;
49
50 return temp;
51}
52EXPORT_SYMBOL_GPL(acpi_lpat_raw_to_temp);
53
54/**
55 * acpi_lpat_temp_to_raw(): Return raw value from temperature through
56 * LPAT conversion table
57 *
58 * @lpat_table: the temperature_raw mapping table
59 * @temp: the temperature, used as a key to get the raw value from the
60 * above mapping table
61 *
62 * The raw value will be returned on success,
63 * a negative errno will be returned in error cases.
64 */
65int acpi_lpat_temp_to_raw(struct acpi_lpat_conversion_table *lpat_table,
66 int temp)
67{
68 int i, delta_temp, delta_raw, raw;
69 struct acpi_lpat *lpat = lpat_table->lpat;
70
71 for (i = 0; i < lpat_table->lpat_count - 1; i++) {
72 if (temp >= lpat[i].temp && temp <= lpat[i+1].temp)
73 break;
74 }
75
76 if (i == lpat_table->lpat_count - 1)
77 return -ENOENT;
78
79 delta_temp = lpat[i+1].temp - lpat[i].temp;
80 delta_raw = lpat[i+1].raw - lpat[i].raw;
81 raw = lpat[i].raw + (temp - lpat[i].temp) * delta_raw / delta_temp;
82
83 return raw;
84}
85EXPORT_SYMBOL_GPL(acpi_lpat_temp_to_raw);
86
87/**
88 * acpi_lpat_get_conversion_table(): Parse ACPI LPAT table if present.
89 *
90 * @handle: Handle to acpi device
91 *
92 * Parse LPAT table to a struct of type acpi_lpat_table. On success
93 * it returns a pointer to newly allocated table. This table must
94 * be freed by the caller when finished processing, using a call to
95 * acpi_lpat_free_conversion_table.
96 */
97struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(acpi_handle
98 handle)
99{
100 struct acpi_lpat_conversion_table *lpat_table = NULL;
101 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
102 union acpi_object *obj_p, *obj_e;
103 int *lpat, i;
104 acpi_status status;
105
106 status = acpi_evaluate_object(handle, "LPAT", NULL, &buffer);
107 if (ACPI_FAILURE(status))
108 return NULL;
109
110 obj_p = (union acpi_object *)buffer.pointer;
111 if (!obj_p || (obj_p->type != ACPI_TYPE_PACKAGE) ||
112 (obj_p->package.count % 2) || (obj_p->package.count < 4))
113 goto out;
114
115 lpat = kcalloc(obj_p->package.count, sizeof(int), GFP_KERNEL);
116 if (!lpat)
117 goto out;
118
119 for (i = 0; i < obj_p->package.count; i++) {
120 obj_e = &obj_p->package.elements[i];
121 if (obj_e->type != ACPI_TYPE_INTEGER) {
122 kfree(lpat);
123 goto out;
124 }
125 lpat[i] = (s64)obj_e->integer.value;
126 }
127
128 lpat_table = kzalloc(sizeof(*lpat_table), GFP_KERNEL);
129 if (!lpat_table) {
130 kfree(lpat);
131 goto out;
132 }
133
134 lpat_table->lpat = (struct acpi_lpat *)lpat;
135 lpat_table->lpat_count = obj_p->package.count / 2;
136
137out:
138 kfree(buffer.pointer);
139 return lpat_table;
140}
141EXPORT_SYMBOL_GPL(acpi_lpat_get_conversion_table);
142
143/**
144 * acpi_lpat_free_conversion_table(): Free LPAT table.
145 *
146 * @lpat_table: the temperature_raw mapping table structure
147 *
148 * Frees the LPAT table previously allocated by a call to
149 * acpi_lpat_get_conversion_table.
150 */
151void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table
152 *lpat_table)
153{
154 if (lpat_table) {
155 kfree(lpat_table->lpat);
156 kfree(lpat_table);
157 }
158}
159EXPORT_SYMBOL_GPL(acpi_lpat_free_conversion_table);
160