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Kernel driver lm70
Supported chips:
* National Semiconductor LM70
* Texas Instruments TMP121/TMP123
* Texas Instruments TMP122/TMP124
* Texas Instruments TMP125
* National Semiconductor LM71
* National Semiconductor LM74
Kaiwan N Billimoria <>
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 <> for mentoring the hwmon-side driver