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cubelinux-kernel/Documentation/hwmon/lm70.rst
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Greg Kroah-Hartman 598cf27219 Linux 6.19.3
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com>
Tested-by: Peter Schneider <pschneider1968@googlemail.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Tested-by: Brett A C Sheffield <bacs@librecast.net>
Tested-by: Mark Brown <broonie@kernel.org>
Tested-by: Luna Jernberg <droidbittin@gmail.com>
Tested-by: Ronald Warsow <rwarsow@gmx.de>
Tested-by: Justin M. Forbes <jforbes@fedoraproject.org>
Tested-by: Ron Economos <re@w6rz.net>
Tested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-02-19 16:33:27 +01:00

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Kernel driver lm70
==================
Supported chips:
* National Semiconductor LM70
Datasheet: https://www.ti.com/product/LM70
* Texas Instruments TMP121/TMP123
Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html
* Texas Instruments TMP122/TMP124
Information: https://www.ti.com/product/tmp122
* Texas Instruments TMP125
Information: https://www.ti.com/product/tmp125
* National Semiconductor LM71
Datasheet: https://www.ti.com/product/LM71
* National Semiconductor LM74
Datasheet: https://www.ti.com/product/LM74
Author:
Kaiwan N Billimoria <kaiwan@designergraphix.com>
Description
-----------
This driver implements support for the National Semiconductor LM70
temperature sensor.
The LM70 temperature sensor chip supports a single temperature sensor.
It communicates with a host processor (or microcontroller) via an
SPI/Microwire Bus interface.
Communication with the LM70 is simple: when the temperature is to be sensed,
the driver accesses the LM70 using SPI communication: 16 SCLK cycles
comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's
complement digital temperature (sent via the SIO line), is available in the
driver for interpretation. This driver makes use of the kernel's in-core
SPI support.
As a real (in-tree) example of this "SPI protocol driver" interfacing
with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c
and its associated documentation.
The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is
13-bit temperature data (0.0625 degrees celsius resolution).
The TMP122/TMP124 also feature configurable temperature thresholds.
The TMP125 is less accurate and provides 10-bit temperature data
with 0.25 degrees Celsius resolution.
The LM71 is also very similar; main difference is 14-bit temperature
data (0.03125 degrees celsius resolution).
Thanks to
---------
Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driver
development.