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From:   Akinobu Mita <akinobu.mita@gmail.com>
To:     linux-nvme@lists.infradead.org, linux-hwmon@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Akinobu Mita <akinobu.mita@gmail.com>,
        Sujith Thomas <sujith.thomas@intel.com>,
        Darren Hart <dvhart@infradead.org>,
        Andy Shevchenko <andy@infradead.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Amit Kucheria <amit.kucheria@verdurent.com>,
        Jean Delvare <jdelvare@suse.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>
Subject: [PATCH v2 1/8] add header file for kelvin to/from Celsius conversion helpers
Date:   Thu, 28 Nov 2019 23:54:32 +0900
Message-Id: <1574952879-7200-2-git-send-email-akinobu.mita@gmail.com>
In-Reply-To: <1574952879-7200-1-git-send-email-akinobu.mita@gmail.com>
References: <1574952879-7200-1-git-send-email-akinobu.mita@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
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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@intel.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Andy Shevchenko <andy@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>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.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
+
+#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);
+}
+
+/**
+ * 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 */
-- 
2.7.4