[1/8] add header file for kelvin to/from Celsius conversion helpers

Commit Message

Akinobu Mita Nov. 24, 2019, 2:08 p.m. UTC

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 <[e-mail]>
Cc: Darren Hart <[e-mail]>
Cc: Andy Shevchenko <[e-mail]>
Cc: Zhang Rui <[e-mail]>
Cc: Eduardo Valentin <[e-mail]>
Cc: Daniel Lezcano <[e-mail]>
Cc: Amit Kucheria <[e-mail]>
Cc: Jean Delvare <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Cc: Keith Busch <[e-mail]>
Cc: Jens Axboe <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Sagi Grimberg <[e-mail]>
Signed-off-by: Akinobu Mita <[e-mail]>
---
 include/linux/temperature.h | 39 +++++++++++++++++++++++++++++++++++++++
 include/linux/thermal.h     |  1 +
 2 files changed, 40 insertions(+)
 create mode 100644 include/linux/temperature.h

Comments

Andy Shevchenko Nov. 24, 2019, 2:57 p.m. UTC | #1

On Sun, Nov 24, 2019 at 4:09 PM Akinobu Mita <[e-mail]> 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 <[e-mail]>
> Cc: Darren Hart <[e-mail]>
> Cc: Andy Shevchenko <[e-mail]>
> Cc: Zhang Rui <[e-mail]>
> Cc: Eduardo Valentin <[e-mail]>
> Cc: Daniel Lezcano <[e-mail]>
> Cc: Amit Kucheria <[e-mail]>
> Cc: Jean Delvare <[e-mail]>
> Cc: Guenter Roeck <[e-mail]>
> Cc: Keith Busch <[e-mail]>
> Cc: Jens Axboe <[e-mail]>
> Cc: Christoph Hellwig <[e-mail]>
> Cc: Sagi Grimberg <[e-mail]>
> Signed-off-by: Akinobu Mita <[e-mail]>
> ---
>  include/linux/temperature.h | 39 +++++++++++++++++++++++++++++++++++++++

>  include/linux/thermal.h     |  1 +


> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -14,6 +14,7 @@
>  #include <linux/idr.h>
>  #include <linux/device.h>
>  #include <linux/sysfs.h>
> +#include <linux/temperature.h>
>  #include <linux/workqueue.h>
>  #include <uapi/linux/thermal.h>

I don't see any users of it. Why did you include?

Akinobu Mita Nov. 25, 2019, 2:29 p.m. UTC | #2

2019年11月24日(日) 23:57 Andy Shevchenko <[e-mail]>:
>
> On Sun, Nov 24, 2019 at 4:09 PM Akinobu Mita <[e-mail]> 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 <[e-mail]>
> > Cc: Darren Hart <[e-mail]>
> > Cc: Andy Shevchenko <[e-mail]>
> > Cc: Zhang Rui <[e-mail]>
> > Cc: Eduardo Valentin <[e-mail]>
> > Cc: Daniel Lezcano <[e-mail]>
> > Cc: Amit Kucheria <[e-mail]>
> > Cc: Jean Delvare <[e-mail]>
> > Cc: Guenter Roeck <[e-mail]>
> > Cc: Keith Busch <[e-mail]>
> > Cc: Jens Axboe <[e-mail]>
> > Cc: Christoph Hellwig <[e-mail]>
> > Cc: Sagi Grimberg <[e-mail]>
> > Signed-off-by: Akinobu Mita <[e-mail]>
> > ---
> >  include/linux/temperature.h | 39 +++++++++++++++++++++++++++++++++++++++
>
> >  include/linux/thermal.h     |  1 +
>
>
> > --- a/include/linux/thermal.h
> > +++ b/include/linux/thermal.h
> > @@ -14,6 +14,7 @@
> >  #include <linux/idr.h>
> >  #include <linux/device.h>
> >  #include <linux/sysfs.h>
> > +#include <linux/temperature.h>
> >  #include <linux/workqueue.h>
> >  #include <uapi/linux/thermal.h>
>
> I don't see any users of it. Why did you include?

The rest of this patch series starts using it.

I decided to include <linux/temperature.h> from <linux/thermal.h> because
the existing <linux/thermal.h> provides the conversion helpers.

However, not all of the thermal drivers require these conversion helpers,
so we can change to include <linux/temperature.h> from each thermal driver
instead of including it from <linux/thermal.h>.

Which way do you prefer?

Andy Shevchenko Nov. 25, 2019, 7:05 p.m. UTC | #3

On Mon, Nov 25, 2019 at 4:30 PM Akinobu Mita <[e-mail]> wrote:
> 2019年11月24日(日) 23:57 Andy Shevchenko <[e-mail]>:
> > On Sun, Nov 24, 2019 at 4:09 PM Akinobu Mita <[e-mail]> wrote:

> > >  include/linux/thermal.h     |  1 +

> > > --- a/include/linux/thermal.h
> > > +++ b/include/linux/thermal.h
> > > @@ -14,6 +14,7 @@
> > >  #include <linux/idr.h>
> > >  #include <linux/device.h>
> > >  #include <linux/sysfs.h>
> > > +#include <linux/temperature.h>
> > >  #include <linux/workqueue.h>
> > >  #include <uapi/linux/thermal.h>
> >
> > I don't see any users of it. Why did you include?
>
> The rest of this patch series starts using it.
>
> I decided to include <linux/temperature.h> from <linux/thermal.h> because
> the existing <linux/thermal.h> provides the conversion helpers.
>
> However, not all of the thermal drivers require these conversion helpers,
> so we can change to include <linux/temperature.h> from each thermal driver
> instead of including it from <linux/thermal.h>.
>
> Which way do you prefer?

I think users should include new header explicitly.

Patch

diff --git a/include/linux/temperature.h b/include/linux/temperature.h
new file mode 100644
index 0000000..d7e2aed
--- /dev/null
+++ b/include/linux/temperature.h
@@ -0,0 +1,39 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TEMPERATURE_H
+#define _LINUX_TEMPERATURE_H
+
+#include <linux/kernel.h>
+
+#define ABSOLUTE_ZERO_MILLICELSIUS -273150
+
+static inline long kelvin_to_millicelsius(long t)
+{
+	return t * 1000 + ABSOLUTE_ZERO_MILLICELSIUS;
+}
+
+static inline long millicelsius_to_kelvin(long t)
+{
+	return DIV_ROUND_CLOSEST(t - ABSOLUTE_ZERO_MILLICELSIUS, 1000);
+}
+
+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);
+}
+
+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 */
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index e45659c..ed549e4 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -14,6 +14,7 @@ 
 #include <linux/idr.h>
 #include <linux/device.h>
 #include <linux/sysfs.h>
+#include <linux/temperature.h>
 #include <linux/workqueue.h>
 #include <uapi/linux/thermal.h>