| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | Kernel driver lm70 |
| 2 | ================== |
| 3 | |
| 4 | Supported chips: |
| 5 | * National Semiconductor LM70 |
| 6 | Datasheet: http://www.national.com/pf/LM/LM70.html |
| 7 | * Texas Instruments TMP121/TMP123 |
| 8 | Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html |
| 9 | * Texas Instruments TMP122/TMP124 |
| 10 | Information: http://www.ti.com/product/tmp122 |
| 11 | * National Semiconductor LM71 |
| 12 | Datasheet: http://www.ti.com/product/LM71 |
| 13 | * National Semiconductor LM74 |
| 14 | Datasheet: http://www.ti.com/product/LM74 |
| 15 | |
| 16 | Author: |
| 17 | Kaiwan N Billimoria <kaiwan@designergraphix.com> |
| 18 | |
| 19 | Description |
| 20 | ----------- |
| 21 | |
| 22 | This driver implements support for the National Semiconductor LM70 |
| 23 | temperature sensor. |
| 24 | |
| 25 | The LM70 temperature sensor chip supports a single temperature sensor. |
| 26 | It communicates with a host processor (or microcontroller) via an |
| 27 | SPI/Microwire Bus interface. |
| 28 | |
| 29 | Communication with the LM70 is simple: when the temperature is to be sensed, |
| 30 | the driver accesses the LM70 using SPI communication: 16 SCLK cycles |
| 31 | comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's |
| 32 | complement digital temperature (sent via the SIO line), is available in the |
| 33 | driver for interpretation. This driver makes use of the kernel's in-core |
| 34 | SPI support. |
| 35 | |
| 36 | As a real (in-tree) example of this "SPI protocol driver" interfacing |
| 37 | with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c |
| 38 | and its associated documentation. |
| 39 | |
| 40 | The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is |
| 41 | 13-bit temperature data (0.0625 degrees celsius resolution). |
| 42 | |
| 43 | The TMP122/TMP124 also feature configurable temperature thresholds. |
| 44 | |
| 45 | The LM71 is also very similar; main difference is 14-bit temperature |
| 46 | data (0.03125 degrees celsius resolution). |
| 47 | |
| 48 | Thanks to |
| 49 | --------- |
| 50 | Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driver |
| 51 | development. |