Commit 23331e48 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds

include/linux/units.h: add helpers for kelvin to/from Celsius conversion

Patch series "add header file for kelvin to/from Celsius conversion
helpers", v4.

There are several helper macros to convert kelvin to/from Celsius in
<linux/thermal.h> for thermal drivers.  These are useful for any other
drivers or subsystems, but it's odd to include <linux/thermal.h> just
for the helpers.

This adds a new <linux/units.h> that provides the equivalent inline
functions for any drivers or subsystems, and switches all the users of
conversion helpers in <linux/thermal.h> to use <linux/units.h> helpers.

This patch (of 12):

There are several helper macros to convert kelvin to/from Celsius in
<linux/thermal.h> for thermal drivers.  These are useful for any other
drivers or subsystems, but it's odd to include <linux/thermal.h> just
for the helpers.

This adds a new <linux/units.h> that provides the equivalent inline
functions for any drivers or subsystems.  It is intended to replace the
helpers in <linux/thermal.h>.

Link: http://lkml.kernel.org/r/1576386975-7941-2-git-send-email-akinobu.mita@gmail.comSigned-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Cc: Sujith Thomas <sujith.thomas@intel.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Amit Kucheria <amit.kucheria@verdurent.com>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3b82a051
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_UNITS_H
#define _LINUX_UNITS_H
#include <linux/kernel.h>
#define ABSOLUTE_ZERO_MILLICELSIUS -273150
static inline long milli_kelvin_to_millicelsius(long t)
{
return t + ABSOLUTE_ZERO_MILLICELSIUS;
}
static inline long millicelsius_to_milli_kelvin(long t)
{
return t - ABSOLUTE_ZERO_MILLICELSIUS;
}
#define MILLIDEGREE_PER_DEGREE 1000
#define MILLIDEGREE_PER_DECIDEGREE 100
static inline long kelvin_to_millicelsius(long t)
{
return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
}
static inline long millicelsius_to_kelvin(long t)
{
t = millicelsius_to_milli_kelvin(t);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
}
static inline long deci_kelvin_to_celsius(long t)
{
t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
}
static inline long celsius_to_deci_kelvin(long t)
{
t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
}
/**
* deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
* @t: temperature value in decidegrees Kelvin
* @offset: difference between Kelvin and Celsius in millidegrees
*
* Return: temperature value in millidegrees Celsius
*/
static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
{
return t * MILLIDEGREE_PER_DECIDEGREE - offset;
}
static inline long deci_kelvin_to_millicelsius(long t)
{
return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
}
static inline long millicelsius_to_deci_kelvin(long t)
{
t = millicelsius_to_milli_kelvin(t);
return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
}
static inline long kelvin_to_celsius(long t)
{
return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
MILLIDEGREE_PER_DEGREE);
}
static inline long celsius_to_kelvin(long t)
{
return t - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
MILLIDEGREE_PER_DEGREE);
}
#endif /* _LINUX_UNITS_H */
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