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The TMP125 is a 2 degree Celsius accurate Digital Temperature Sensor with a SPI interface. The temperature register is a 16-bit, read-only register. The MSB (Bit 15) is a leading zero and never set. Bits 14 to 5 are the 1+9 temperature data bits in a two's complement format. Bits 4 to 0 are useless copies of Bit 5 value and therefore ignored. This was tested on a Aerohive HiveAP-350. Bonus: lm70 supports TMP122/TMP124 as well. I added them to the Kconfig module description. Signed-off-by: Christian Lamparter <chunkeey@gmail.com> Link: https://lore.kernel.org/r/43b19cbd4e7f51e9509e561b02b5d8d0e7079fac.1645175187.git.chunkeey@gmail.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
70 lines
2.0 KiB
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70 lines
2.0 KiB
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Kernel driver lm70
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==================
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Supported chips:
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* National Semiconductor LM70
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Datasheet: http://www.national.com/pf/LM/LM70.html
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* Texas Instruments TMP121/TMP123
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Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html
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* Texas Instruments TMP122/TMP124
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Information: https://www.ti.com/product/tmp122
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* Texas Instruments TMP125
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Information: https://www.ti.com/product/tmp125
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* National Semiconductor LM71
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Datasheet: https://www.ti.com/product/LM71
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* National Semiconductor LM74
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Datasheet: https://www.ti.com/product/LM74
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Author:
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Kaiwan N Billimoria <kaiwan@designergraphix.com>
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Description
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-----------
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This driver implements support for the National Semiconductor LM70
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temperature sensor.
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The LM70 temperature sensor chip supports a single temperature sensor.
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It communicates with a host processor (or microcontroller) via an
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SPI/Microwire Bus interface.
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Communication with the LM70 is simple: when the temperature is to be sensed,
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the driver accesses the LM70 using SPI communication: 16 SCLK cycles
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comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's
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complement digital temperature (sent via the SIO line), is available in the
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driver for interpretation. This driver makes use of the kernel's in-core
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SPI support.
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As a real (in-tree) example of this "SPI protocol driver" interfacing
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with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c
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and its associated documentation.
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The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is
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13-bit temperature data (0.0625 degrees celsius resolution).
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The TMP122/TMP124 also feature configurable temperature thresholds.
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The TMP125 is less accurate and provides 10-bit temperature data
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with 0.25 degrees Celsius resolution.
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The LM71 is also very similar; main difference is 14-bit temperature
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data (0.03125 degrees celsius resolution).
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Thanks to
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---------
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Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driver
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development.
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