152 lines
4.0 KiB
C
152 lines
4.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* acpi_lpat.c - LPAT table processing functions
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*
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* Copyright (C) 2015 Intel Corporation. All rights reserved.
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*/
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#include <linux/export.h>
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#include <linux/acpi.h>
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#include <acpi/acpi_lpat.h>
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/**
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* acpi_lpat_raw_to_temp(): Return temperature from raw value through
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* LPAT conversion table
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*
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* @lpat_table: the temperature_raw mapping table structure
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* @raw: the raw value, used as a key to get the temperature from the
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* above mapping table
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*
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* A positive converted temperature value will be returned on success,
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* a negative errno will be returned in error cases.
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*/
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int acpi_lpat_raw_to_temp(struct acpi_lpat_conversion_table *lpat_table,
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int raw)
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{
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int i, delta_temp, delta_raw, temp;
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struct acpi_lpat *lpat = lpat_table->lpat;
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for (i = 0; i < lpat_table->lpat_count - 1; i++) {
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if ((raw >= lpat[i].raw && raw <= lpat[i+1].raw) ||
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(raw <= lpat[i].raw && raw >= lpat[i+1].raw))
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break;
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}
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if (i == lpat_table->lpat_count - 1)
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return -ENOENT;
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delta_temp = lpat[i+1].temp - lpat[i].temp;
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delta_raw = lpat[i+1].raw - lpat[i].raw;
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temp = lpat[i].temp + (raw - lpat[i].raw) * delta_temp / delta_raw;
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return temp;
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}
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EXPORT_SYMBOL_GPL(acpi_lpat_raw_to_temp);
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/**
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* acpi_lpat_temp_to_raw(): Return raw value from temperature through
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* LPAT conversion table
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*
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* @lpat_table: the temperature_raw mapping table
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* @temp: the temperature, used as a key to get the raw value from the
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* above mapping table
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*
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* The raw value will be returned on success,
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* a negative errno will be returned in error cases.
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*/
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int acpi_lpat_temp_to_raw(struct acpi_lpat_conversion_table *lpat_table,
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int temp)
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{
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int i, delta_temp, delta_raw, raw;
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struct acpi_lpat *lpat = lpat_table->lpat;
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for (i = 0; i < lpat_table->lpat_count - 1; i++) {
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if (temp >= lpat[i].temp && temp <= lpat[i+1].temp)
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break;
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}
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if (i == lpat_table->lpat_count - 1)
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return -ENOENT;
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delta_temp = lpat[i+1].temp - lpat[i].temp;
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delta_raw = lpat[i+1].raw - lpat[i].raw;
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raw = lpat[i].raw + (temp - lpat[i].temp) * delta_raw / delta_temp;
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return raw;
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}
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EXPORT_SYMBOL_GPL(acpi_lpat_temp_to_raw);
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/**
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* acpi_lpat_get_conversion_table(): Parse ACPI LPAT table if present.
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*
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* @handle: Handle to acpi device
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*
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* Parse LPAT table to a struct of type acpi_lpat_table. On success
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* it returns a pointer to newly allocated table. This table must
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* be freed by the caller when finished processing, using a call to
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* acpi_lpat_free_conversion_table.
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*/
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struct acpi_lpat_conversion_table *acpi_lpat_get_conversion_table(acpi_handle
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handle)
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{
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struct acpi_lpat_conversion_table *lpat_table = NULL;
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struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
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union acpi_object *obj_p, *obj_e;
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int *lpat, i;
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acpi_status status;
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status = acpi_evaluate_object(handle, "LPAT", NULL, &buffer);
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if (ACPI_FAILURE(status))
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return NULL;
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obj_p = (union acpi_object *)buffer.pointer;
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if (!obj_p || (obj_p->type != ACPI_TYPE_PACKAGE) ||
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(obj_p->package.count % 2) || (obj_p->package.count < 4))
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goto out;
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lpat = kcalloc(obj_p->package.count, sizeof(int), GFP_KERNEL);
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if (!lpat)
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goto out;
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for (i = 0; i < obj_p->package.count; i++) {
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obj_e = &obj_p->package.elements[i];
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if (obj_e->type != ACPI_TYPE_INTEGER) {
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kfree(lpat);
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goto out;
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}
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lpat[i] = (s64)obj_e->integer.value;
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}
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lpat_table = kzalloc(sizeof(*lpat_table), GFP_KERNEL);
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if (!lpat_table) {
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kfree(lpat);
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goto out;
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}
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lpat_table->lpat = (struct acpi_lpat *)lpat;
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lpat_table->lpat_count = obj_p->package.count / 2;
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out:
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kfree(buffer.pointer);
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return lpat_table;
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}
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EXPORT_SYMBOL_GPL(acpi_lpat_get_conversion_table);
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/**
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* acpi_lpat_free_conversion_table(): Free LPAT table.
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*
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* @lpat_table: the temperature_raw mapping table structure
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*
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* Frees the LPAT table previously allocated by a call to
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* acpi_lpat_get_conversion_table.
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*/
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void acpi_lpat_free_conversion_table(struct acpi_lpat_conversion_table
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*lpat_table)
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{
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if (lpat_table) {
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kfree(lpat_table->lpat);
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kfree(lpat_table);
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}
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}
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EXPORT_SYMBOL_GPL(acpi_lpat_free_conversion_table);
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