projects / mirror_ubuntu-kernels.git / blame
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|---|---|---|
| e1a8e913 KB |
1 | Kernel driver lm70 |
| 2 | ================== | |
| 3 | ||
| c8ac32e4 | 4 | Supported chips: |
| b04f2f7d | 5 | |
| e1a8e913 | 6 | * National Semiconductor LM70 |
| b04f2f7d | 7 | |
| e1a8e913 | 8 | Datasheet: http://www.national.com/pf/LM/LM70.html |
| b04f2f7d | 9 | |
| c8ac32e4 | 10 | * Texas Instruments TMP121/TMP123 |
| b04f2f7d | 11 | |
| c8ac32e4 | 12 | Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html |
| b04f2f7d | 13 | |
| 68f0c8c9 | 14 | * Texas Instruments TMP122/TMP124 |
| b04f2f7d | 15 | |
| ad736c1a | 16 | Information: https://www.ti.com/product/tmp122 |
| b04f2f7d | 17 | |
| cd929672 CL |
18 | * Texas Instruments TMP125 |
| 19 | ||
| 20 | Information: https://www.ti.com/product/tmp125 | |
| 21 | ||
| a86e94dc | 22 | * National Semiconductor LM71 |
| b04f2f7d | 23 | |
| ad736c1a | 24 | Datasheet: https://www.ti.com/product/LM71 |
| b04f2f7d | 25 | |
| a86e94dc | 26 | * National Semiconductor LM74 |
| b04f2f7d | 27 | |
| ad736c1a | 28 | Datasheet: https://www.ti.com/product/LM74 |
| e1a8e913 | 29 | |
| b04f2f7d | 30 | |
| e1a8e913 | 31 | Author: |
| b04f2f7d | 32 | Kaiwan N Billimoria <kaiwan@designergraphix.com> |
| e1a8e913 KB |
33 | |
| 34 | Description | |
| 35 | ----------- | |
| 36 | ||
| 37 | This driver implements support for the National Semiconductor LM70 | |
| 38 | temperature sensor. | |
| 39 | ||
| 40 | The LM70 temperature sensor chip supports a single temperature sensor. | |
| 41 | It communicates with a host processor (or microcontroller) via an | |
| 42 | SPI/Microwire Bus interface. | |
| 43 | ||
| 44 | Communication with the LM70 is simple: when the temperature is to be sensed, | |
| 45 | the driver accesses the LM70 using SPI communication: 16 SCLK cycles | |
| 46 | comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's | |
| 47 | complement digital temperature (sent via the SIO line), is available in the | |
| 48 | driver for interpretation. This driver makes use of the kernel's in-core | |
| 49 | SPI support. | |
| 50 | ||
| 2b730051 KB |
51 | As a real (in-tree) example of this "SPI protocol driver" interfacing |
| 52 | with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c | |
| 53 | and its associated documentation. | |
| 54 | ||
| 68f0c8c9 FF |
55 | The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is |
| 56 | 13-bit temperature data (0.0625 degrees celsius resolution). | |
| 57 | ||
| 58 | The TMP122/TMP124 also feature configurable temperature thresholds. | |
| a86e94dc | 59 | |
| cd929672 CL |
60 | The TMP125 is less accurate and provides 10-bit temperature data |
| 61 | with 0.25 degrees Celsius resolution. | |
| 62 | ||
| a86e94dc CL |
63 | The LM71 is also very similar; main difference is 14-bit temperature |
| 64 | data (0.03125 degrees celsius resolution). | |
| c8ac32e4 | 65 | |
| e1a8e913 KB |
66 | Thanks to |
| 67 | --------- | |
| 7c81c60f | 68 | Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driver |
| e1a8e913 | 69 | development. |