acpi_lpat.c
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/*
* acpi_lpat.c - LPAT table processing functions
*
* Copyright (C) 2015 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/module.h>
#include <linux/acpi.h>
#include <acpi/acpi_lpat.h>
/**
* acpi_lpat_raw_to_temp(): Return temperature from raw value through
* LPAT conversion table
*
* @lpat_table: the temperature_raw mapping table structure
* @raw: the raw value, used as a key to get the temerature from the
* above mapping table
*
* A positive converted temperarure value will be returned on success,
* a negative errno will be returned in error cases.
*/
int acpi_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
int raw)
{
int i, delta_temp, delta_raw, temp;
struct acpi_lpat *lpat = lpat_table->lpat;
for (i = 0; i < lpat_table->lpat_count - 1; i++) {
if ((raw >= lpat[i].raw && raw <= lpat[i+1].raw) ||
(raw <= lpat[i].raw && raw >= lpat[i+1].raw))
break;
}
if (i == lpat_table->lpat_count - 1)
return -ENOENT;
delta_temp = lpat[i+1].temp - lpat[i].temp;
delta_raw = lpat[i+1].raw - lpat[i].raw;
temp = lpat[i].temp + (raw - lpat[i].raw) * delta_temp / delta_raw;
return temp;
}
EXPORT_SYMBOL_GPL(acpi_lpat_raw_to_temp);
/**
* acpi_lpat_temp_to_raw(): Return raw value from temperature through
* LPAT conversion table
*
* @lpat: the temperature_raw mapping table
* @temp: the temperature, used as a key to get the raw value from the
* above mapping table
*
* A positive converted temperature value will be returned on success,
* a negative errno will be returned in error cases.
*/
int acpi_lpat_temp_to_raw(struct acpi_lpat_conversion_table *lpat_table,
int temp)
{
int i, delta_temp, delta_raw, raw;
struct acpi_lpat *lpat = lpat_table->lpat;
for (i = 0; i < lpat_table->lpat_count - 1; i++) {
if (temp >= lpat[i].temp && temp <= lpat[i+1].temp)
break;
}
if (i == lpat_table->lpat_count - 1)
return -ENOENT;
delta_temp = lpat[i+1].temp - lpat[i].temp;
delta_raw = lpat[i+1].raw - lpat[i].raw;
raw = lpat[i].raw + (temp - lpat[i].temp) * delta_raw / delta_temp;
return raw;
}
EXPORT_SYMBOL_GPL(acpi_lpat_temp_to_raw);
/**
* acpi_lpat_get_conversion_table(): Parse ACPI LPAT table if present.
*
* @handle: Handle to acpi device
*
* Parse LPAT table to a struct of type acpi_lpat_table. On success
* it returns a pointer to newly allocated table. This table must
* be freed by the caller when finished processing, using a call to
* acpi_lpat_free_conversion_table.
*/
struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(acpi_handle
handle)
{
struct acpi_lpat_conversion_table *lpat_table = NULL;
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
union acpi_object *obj_p, *obj_e;
int *lpat, i;
acpi_status status;
status = acpi_evaluate_object(handle, "LPAT", NULL, &buffer);
if (ACPI_FAILURE(status))
return NULL;
obj_p = (union acpi_object *)buffer.pointer;
if (!obj_p || (obj_p->type != ACPI_TYPE_PACKAGE) ||
(obj_p->package.count % 2) || (obj_p->package.count < 4))
goto out;
lpat = kcalloc(obj_p->package.count, sizeof(int), GFP_KERNEL);
if (!lpat)
goto out;
for (i = 0; i < obj_p->package.count; i++) {
obj_e = &obj_p->package.elements[i];
if (obj_e->type != ACPI_TYPE_INTEGER) {
kfree(lpat);
goto out;
}
lpat[i] = (s64)obj_e->integer.value;
}
lpat_table = kzalloc(sizeof(*lpat_table), GFP_KERNEL);
if (!lpat_table) {
kfree(lpat);
goto out;
}
lpat_table->lpat = (struct acpi_lpat *)lpat;
lpat_table->lpat_count = obj_p->package.count / 2;
out:
kfree(buffer.pointer);
return lpat_table;
}
EXPORT_SYMBOL_GPL(acpi_lpat_get_conversion_table);
/**
* acpi_lpat_free_conversion_table(): Free LPAT table.
*
* @lpat_table: the temperature_raw mapping table structure
*
* Frees the LPAT table previously allocated by a call to
* acpi_lpat_get_conversion_table.
*/
void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table
*lpat_table)
{
if (lpat_table) {
kfree(lpat_table->lpat);
kfree(lpat_table);
}
}
EXPORT_SYMBOL_GPL(acpi_lpat_free_conversion_table);
MODULE_LICENSE("GPL");