Description¶

This driver implements support for the National Semiconductor LM70temperature sensor.

The LM70 temperature sensor chip supports a single temperature sensor.It communicates with a host processor (or microcontroller) via anSPI/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 cyclescomprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2’scomplement digital temperature (sent via the SIO line), is available in thedriver for interpretation. This driver makes use of the kernel’s in-coreSPI support.

As a real (in-tree) example of this “SPI protocol driver” interfacingwith a “SPI master controller driver”, see drivers/spi/spi_lm70llp.cand its associated documentation.

The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is13-bit temperature data (0.0625 degrees celsius resolution).

The TMP122/TMP124 also feature configurable temperature thresholds.

The LM71 is also very similar; main difference is 14-bit temperaturedata (0.03125 degrees celsius resolution).

Thanks to¶

Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driverdevelopment.