From 426343ef34fac426e619176c84cb2e263b9ed23d Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Thu, 13 Oct 2011 17:15:11 -0400 Subject: hwmon: (lm75) Document why clones are not detected Explain why clones of the LM75 are generally not detected by the driver, and why this isn't going to change. Also update the documentation to reflect the list of chip names currently supported by the driver. Signed-off-by: Jean Delvare Signed-off-by: Guenter Roeck --- Documentation/hwmon/lm75 | 58 ++++++++++++++++++++++++++++-------------------- 1 file changed, 34 insertions(+), 24 deletions(-) (limited to 'Documentation') diff --git a/Documentation/hwmon/lm75 b/Documentation/hwmon/lm75 index 8d40d0fda10a..c91a1d15fa28 100644 --- a/Documentation/hwmon/lm75 +++ b/Documentation/hwmon/lm75 @@ -12,31 +12,46 @@ Supported chips: Addresses scanned: I2C 0x48 - 0x4f Datasheet: Publicly available at the National Semiconductor website http://www.national.com/ - * Dallas Semiconductor DS75 - Prefix: 'lm75' - Addresses scanned: I2C 0x48 - 0x4f - Datasheet: Publicly available at the Dallas Semiconductor website - http://www.maxim-ic.com/ - * Dallas Semiconductor DS1775 - Prefix: 'lm75' - Addresses scanned: I2C 0x48 - 0x4f + * Dallas Semiconductor DS75, DS1775 + Prefixes: 'ds75', 'ds1775' + Addresses scanned: none Datasheet: Publicly available at the Dallas Semiconductor website http://www.maxim-ic.com/ * Maxim MAX6625, MAX6626 - Prefix: 'lm75' - Addresses scanned: I2C 0x48 - 0x4b + Prefixes: 'max6625', 'max6626' + Addresses scanned: none Datasheet: Publicly available at the Maxim website http://www.maxim-ic.com/ * Microchip (TelCom) TCN75 Prefix: 'lm75' - Addresses scanned: I2C 0x48 - 0x4f + Addresses scanned: none + Datasheet: Publicly available at the Microchip website + http://www.microchip.com/ + * Microchip MCP9800, MCP9801, MCP9802, MCP9803 + Prefix: 'mcp980x' + Addresses scanned: none Datasheet: Publicly available at the Microchip website http://www.microchip.com/ * Analog Devices ADT75 Prefix: 'adt75' - Addresses scanned: I2C 0x48 - 0x4f + Addresses scanned: none Datasheet: Publicly available at the Analog Devices website http://www.analog.com/adt75 + * ST Microelectronics STDS75 + Prefix: 'stds75' + Addresses scanned: none + Datasheet: Publicly available at the ST website + http://www.st.com/internet/analog/product/121769.jsp + * Texas Instruments TMP100, TMP101, TMP105, TMP75, TMP175, TMP275 + Prefixes: 'tmp100', 'tmp101', 'tmp105', 'tmp175', 'tmp75', 'tmp275' + Addresses scanned: none + Datasheet: Publicly available at the Texas Instruments website + http://www.ti.com/product/tmp100 + http://www.ti.com/product/tmp101 + http://www.ti.com/product/tmp105 + http://www.ti.com/product/tmp75 + http://www.ti.com/product/tmp175 + http://www.ti.com/product/tmp275 Author: Frodo Looijaard @@ -55,21 +70,16 @@ range of -55 to +125 degrees. The LM75 only updates its values each 1.5 seconds; reading it more often will do no harm, but will return 'old' values. -The LM75 is usually used in combination with LM78-like chips, to measure -the temperature of the processor(s). - -The DS75, DS1775, MAX6625, and MAX6626 are supported as well. -They are not distinguished from an LM75. While most of these chips -have three additional bits of accuracy (12 vs. 9 for the LM75), -the additional bits are not supported. Not only that, but these chips will -not be detected if not in 9-bit precision mode (use the force parameter if -needed). - -The TCN75 is supported as well, and is not distinguished from an LM75. +The original LM75 was typically used in combination with LM78-like chips +on PC motherboards, to measure the temperature of the processor(s). Clones +are now used in various embedded designs. The LM75 is essentially an industry standard; there may be other LM75 clones not listed here, with or without various enhancements, -that are supported. +that are supported. The clones are not detected by the driver, unless +they reproduce the exact register tricks of the original LM75, and must +therefore be instantiated explicitly. The specific enhancements (such as +higher resolution) are not currently supported by the driver. The LM77 is not supported, contrary to what we pretended for a long time. Both chips are simply not compatible, value encoding differs. -- cgit v1.2.3