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Message-ID: <5f85f65c-78b6-0b63-f975-a216f9823985@linaro.org>
Date: Fri, 6 Dec 2019 17:49:18 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Akinobu Mita <akinobu.mita@...il.com>,
linux-nvme@...ts.infradead.org, linux-hwmon@...r.kernel.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Sujith Thomas <sujith.thomas@...el.com>,
Darren Hart <dvhart@...radead.org>,
Andy Shevchenko <andy@...radead.org>,
Zhang Rui <rui.zhang@...el.com>,
Amit Kucheria <amit.kucheria@...durent.com>,
Jean Delvare <jdelvare@...e.com>,
Guenter Roeck <linux@...ck-us.net>,
Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...com>,
Christoph Hellwig <hch@....de>,
Sagi Grimberg <sagi@...mberg.me>
Subject: Re: [PATCH v2 1/8] add header file for kelvin to/from Celsius
conversion helpers
On 28/11/2019 15:54, Akinobu Mita wrote:
> 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/temperature.h> that provides the equivalent inline
> functions for any drivers or subsystems. It is intended to replace the
> helpers in <linux/thermal.h>.
>
> Cc: Sujith Thomas <sujith.thomas@...el.com>
> Cc: Darren Hart <dvhart@...radead.org>
> Cc: Andy Shevchenko <andy@...radead.org>
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Amit Kucheria <amit.kucheria@...durent.com>
> Cc: Jean Delvare <jdelvare@...e.com>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Keith Busch <kbusch@...nel.org>
> Cc: Jens Axboe <axboe@...com>
> Cc: Christoph Hellwig <hch@....de>
> Cc: Sagi Grimberg <sagi@...mberg.me>
> Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
> ---
> * v2
> - add deci_kelvin_to_millicelsius_with_offset() in linux/temperature.h
> - stop including linux/temperature.h from linux/thermal.h
>
> include/linux/temperature.h | 51 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
> create mode 100644 include/linux/temperature.h
>
> diff --git a/include/linux/temperature.h b/include/linux/temperature.h
> new file mode 100644
> index 0000000..679e70a
> --- /dev/null
> +++ b/include/linux/temperature.h
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_TEMPERATURE_H
> +#define _LINUX_TEMPERATURE_H
It sounds strange to create a temperature file just for a few conversion
functions. Why not create an units.h file, so some more conversions
could be added later (not necessarily related to temperature) ?
> +#include <linux/kernel.h>
> +
> +#define ABSOLUTE_ZERO_MILLICELSIUS -273150
> +
> +static inline long kelvin_to_millicelsius(long t)
Why 'long' ?
> +{
> + return t * 1000 + ABSOLUTE_ZERO_MILLICELSIUS;
> +}
> +
> +static inline long millicelsius_to_kelvin(long t)
> +{
> + return DIV_ROUND_CLOSEST(t - ABSOLUTE_ZERO_MILLICELSIUS, 1000);
Please don't duplicate these operations, just do the conversion to the
right unit and then call a single function.
Replace the constant by macros like what we find in time64.h.
eg.
#define MILLICELSIUS_PER_CELCIUS 1000
So you can really do the cleanup in all the drivers, like removing:
drivers/iio/adc/qcom-vadc-common.h:#define KELVINMIL_CELSIUSMIL
273150
drivers/iio/pressure/st_pressure_core.c:#define MCELSIUS_PER_CELSIUS
1000
drivers/hwmon/xgene-hwmon.c:#define CELSIUS_TO_mCELSIUS(x)
((x) * 1000)
drivers/net/wireless/intel/iwlegacy/common.h:#define
KELVIN_TO_CELSIUS(x) ((x)-273)
drivers/net/wireless/intel/iwlegacy/common.h:#define
CELSIUS_TO_KELVIN(x) ((x)+273)
drivers/net/wireless/intel/iwlwifi/dvm/dev.h:#define
KELVIN_TO_CELSIUS(x) ((x)-273)
drivers/net/wireless/intel/iwlwifi/dvm/dev.h:#define
CELSIUS_TO_KELVIN(x) ((x)+273)
drivers/power/supply/sbs-battery.c:#define TEMP_KELVIN_TO_CELSIUS
2731
drivers/thermal/armada_thermal.c:#define TO_MCELSIUS(c)
((c) * 1000)
drivers/thermal/rcar_gen3_thermal.c:#define MCELSIUS(temp) ((temp)
* 1000)
drivers/thermal/rcar_thermal.c:#define MCELSIUS(temp)
((temp) * 1000)
drivers/thermal/samsung/exynos_tmu.c:#define MCELSIUS 1000
drivers/thermal/samsung/exynos_tmu.c: temp /= MCELSIUS;
drivers/thermal/samsung/exynos_tmu.c: hyst /= MCELSIUS;
drivers/thermal/samsung/exynos_tmu.c: ref = trips[0].temperature /
MCELSIUS;
drivers/thermal/samsung/exynos_tmu.c: *temp =
code_to_temp(data, value) * MCELSIUS;
drivers/thermal/samsung/exynos_tmu.c: temp /= MCELSIUS;
> +}
> +
> +static inline long deci_kelvin_to_celsius(long t)
> +{
> + return DIV_ROUND_CLOSEST(t * 100 + ABSOLUTE_ZERO_MILLICELSIUS, 1000);
> +}
> +
> +static inline long celsius_to_deci_kelvin(long t)
> +{
> + return t * 10 - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS, 100);
> +}
> +
> +/**
> + * 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 * 100 - offset;
> +}
> +
> +static inline long deci_kelvin_to_millicelsius(long t)
> +{
> + return t * 100 + ABSOLUTE_ZERO_MILLICELSIUS;
> +}
> +
> +static inline long millicelsius_to_deci_kelvin(long t)
> +{
> + return DIV_ROUND_CLOSEST(t - ABSOLUTE_ZERO_MILLICELSIUS, 100);
> +}
> +
> +#endif /* _LINUX_TEMPERATURE_H */
>
--
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