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/module.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 temperarure 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: 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 * A positive converted temperature 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
161MODULE_LICENSE("GPL");