diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/acpi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/acpi/acpi_lpat.c | 161 |
2 files changed, 162 insertions, 0 deletions
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index f74317cc1ca9..d22253d5b9f8 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -55,6 +55,7 @@ acpi-$(CONFIG_ACPI_PROCFS_POWER) += cm_sbs.o ifdef CONFIG_ACPI_VIDEO acpi-y += video_detect.o endif +acpi-y += acpi_lpat.o # These are (potentially) separate modules diff --git a/drivers/acpi/acpi_lpat.c b/drivers/acpi/acpi_lpat.c new file mode 100644 index 000000000000..feb61c1630eb --- /dev/null +++ b/drivers/acpi/acpi_lpat.c @@ -0,0 +1,161 @@ +/* + * 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"); |