git://bbs.cooldavid.org / net-next-2.6.git / blame
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1 | Kernel driver lm70 |
| 2 | ================== | |
| 3 | ||
| c8ac32e4 | 4 | Supported chips: |
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5 | * National Semiconductor LM70 |
| 6 | Datasheet: http://www.national.com/pf/LM/LM70.html | |
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7 | * Texas Instruments TMP121/TMP123 |
| 8 | Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html | |
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9 | |
| 10 | Author: | |
| 11 | Kaiwan N Billimoria <kaiwan@designergraphix.com> | |
| 12 | ||
| 13 | Description | |
| 14 | ----------- | |
| 15 | ||
| 16 | This driver implements support for the National Semiconductor LM70 | |
| 17 | temperature sensor. | |
| 18 | ||
| 19 | The LM70 temperature sensor chip supports a single temperature sensor. | |
| 20 | It communicates with a host processor (or microcontroller) via an | |
| 21 | SPI/Microwire Bus interface. | |
| 22 | ||
| 23 | Communication with the LM70 is simple: when the temperature is to be sensed, | |
| 24 | the driver accesses the LM70 using SPI communication: 16 SCLK cycles | |
| 25 | comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's | |
| 26 | complement digital temperature (sent via the SIO line), is available in the | |
| 27 | driver for interpretation. This driver makes use of the kernel's in-core | |
| 28 | SPI support. | |
| 29 | ||
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30 | As a real (in-tree) example of this "SPI protocol driver" interfacing |
| 31 | with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c | |
| 32 | and its associated documentation. | |
| 33 | ||
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34 | The TMP121/TMP123 are very similar; main differences are 4 wire SPI inter- |
| 35 | face (read only) and 13-bit temperature data (0.0625 degrees celsius reso- | |
| 36 | lution). | |
| 37 | ||
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38 | Thanks to |
| 39 | --------- | |
| 40 | Jean Delvare <khali@linux-fr.org> for mentoring the hwmon-side driver | |
| 41 | development. |