1 Kernel driver lm70 1 Kernel driver lm70
2 ================== 2 ==================
3 3
4 Supported chips: 4 Supported chips:
5 5
6 * National Semiconductor LM70 6 * National Semiconductor LM70
7 7
8 Datasheet: https://www.ti.com/product/LM70 8 Datasheet: https://www.ti.com/product/LM70
9 9
10 * Texas Instruments TMP121/TMP123 10 * Texas Instruments TMP121/TMP123
11 11
12 Information: http://focus.ti.com/docs/prod 12 Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html
13 13
14 * Texas Instruments TMP122/TMP124 14 * Texas Instruments TMP122/TMP124
15 15
16 Information: https://www.ti.com/product/tm 16 Information: https://www.ti.com/product/tmp122
17 17
18 * Texas Instruments TMP125 18 * Texas Instruments TMP125
19 19
20 Information: https://www.ti.com/product/tm 20 Information: https://www.ti.com/product/tmp125
21 21
22 * National Semiconductor LM71 22 * National Semiconductor LM71
23 23
24 Datasheet: https://www.ti.com/product/LM71 24 Datasheet: https://www.ti.com/product/LM71
25 25
26 * National Semiconductor LM74 26 * National Semiconductor LM74
27 27
28 Datasheet: https://www.ti.com/product/LM74 28 Datasheet: https://www.ti.com/product/LM74
29 29
30 30
31 Author: 31 Author:
32 Kaiwan N Billimoria <kaiwan@designergra 32 Kaiwan N Billimoria <kaiwan@designergraphix.com>
33 33
34 Description 34 Description
35 ----------- 35 -----------
36 36
37 This driver implements support for the Nationa 37 This driver implements support for the National Semiconductor LM70
38 temperature sensor. 38 temperature sensor.
39 39
40 The LM70 temperature sensor chip supports a si 40 The LM70 temperature sensor chip supports a single temperature sensor.
41 It communicates with a host processor (or micr 41 It communicates with a host processor (or microcontroller) via an
42 SPI/Microwire Bus interface. 42 SPI/Microwire Bus interface.
43 43
44 Communication with the LM70 is simple: when th 44 Communication with the LM70 is simple: when the temperature is to be sensed,
45 the driver accesses the LM70 using SPI communi 45 the driver accesses the LM70 using SPI communication: 16 SCLK cycles
46 comprise the MOSI/MISO loop. At the end of the 46 comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's
47 complement digital temperature (sent via the S 47 complement digital temperature (sent via the SIO line), is available in the
48 driver for interpretation. This driver makes u 48 driver for interpretation. This driver makes use of the kernel's in-core
49 SPI support. 49 SPI support.
50 50
51 As a real (in-tree) example of this "SPI proto 51 As a real (in-tree) example of this "SPI protocol driver" interfacing
52 with a "SPI master controller driver", see dri 52 with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c
53 and its associated documentation. 53 and its associated documentation.
54 54
55 The LM74 and TMP121/TMP122/TMP123/TMP124 are v 55 The LM74 and TMP121/TMP122/TMP123/TMP124 are very similar; main difference is
56 13-bit temperature data (0.0625 degrees celsiu 56 13-bit temperature data (0.0625 degrees celsius resolution).
57 57
58 The TMP122/TMP124 also feature configurable te 58 The TMP122/TMP124 also feature configurable temperature thresholds.
59 59
60 The TMP125 is less accurate and provides 10-bi 60 The TMP125 is less accurate and provides 10-bit temperature data
61 with 0.25 degrees Celsius resolution. 61 with 0.25 degrees Celsius resolution.
62 62
63 The LM71 is also very similar; main difference 63 The LM71 is also very similar; main difference is 14-bit temperature
64 data (0.03125 degrees celsius resolution). 64 data (0.03125 degrees celsius resolution).
65 65
66 Thanks to 66 Thanks to
67 --------- 67 ---------
68 Jean Delvare <jdelvare@suse.de> for mentoring t 68 Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driver
69 development. 69 development.
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