On Tue, 8 Mar 2005 13:52:40 +0100 (CET), you wrote: >Hello, > >FYI how planned documentation will look like (really soon) Here is my second version for comments. Cheers, Grant. diff -Naur linux-2.6.11-mm2/Documentation/i2c/chips/adm9240 linux-2.6.11-mm2-p2x/Documentation/i2c/chips/adm9240 --- linux-2.6.11-mm2/Documentation/i2c/chips/adm9240 1970-01-01 10:00:00.000000000 +1000 +++ linux-2.6.11-mm2-p2x/Documentation/i2c/chips/adm9240 2005-03-09 20:38:42.000000000 +1100 @@ -0,0 +1,123 @@ +Kernel driver adm9240 +===================== + +Status: Port to 2.6 in progress. + +Supported chips: + * Analog Devices ADM9240 + Prefix `adm9240' + Addresses scanned: I2C 0x2c - 0x2f + Datasheet: Publicly available at the Analog Devices website + http://www.analog.com/ + + * Dallas Semiconductor DS1780 + Prefix `ds1780' + Addresses scanned: I2C 0x2c - 0x2f + Datasheet: Publicly available at the Dallas Semiconductor (Maxim) website + http://pdfserv.maxim-ic.com/ + + * National Semiconductor LM81 + Prefix `lm81' + Addresses scanned: I2C 0x2c - 0x2f + Datasheet: Publicly available at the National Semiconductor website + http://www.national.com/ + +The I2C addresses listed above assume BIOS has not changed the +chip MSB 5-bit address. Each chip reports a unique manufacturer +identification code as well as the chip revision/stepping level. + +Authors: + Frodo Looijaard <frodol at dds.nl>, + Philip Edelbrock <phil at netroedge.com> + Michiel Rook <michiel at grendelproject.nl> + Grant Coady <gcoady at gmail.com> with guidance from + Jean Delvare <khali at linux-fr.org> + +Description +----------- + +[From ADM9240] The ADM9240 is a complete system hardware monitor for +microprocessor-based systems, providing measurement and limit comparison +of up to four power supplies and two processor core voltages, plus +temperature, two fan speeds and chassis intrusion. Measured values can +be read out via an I2C-compatible serial System Management Bus, and values +for limit comparisons can be programmed in over the same serial bus. The +high speed successive approximation ADC allows frequent sampling of all +analog channels to ensure a fast interrupt response to any out-of-limit +measurement. + + +On chip temperature is reported as degrees Celsius as 9-bit signed data +with resolution of 0.5 degrees Celsius. High and low temperature limits +are 8-bit signed data with resolution of one degree Celsius. The driver +sets temperature interrupt to comparator mode (per lm_sensors standard) +so that an alarm is asserted while the temperature exceeds the high limit, +in comparator mode the low temperature limit is ignored. + + +Two fan tacho inputs are provided, the ADM9240 gates an internal 22.5kHz +via a divisor to an 8-bit counter. Fan speed (rpm) is calculated by: + +rpm = (22.5 x 10^3 x 60) / (count x divisor) + = 1350000 / (count x divisor) where divisor is 1, 2, 4 or 8. + = 1350000 / (count << setting) where setting is 0, 1, 2 or 3. + +The slow fan speed alarm is asserted when the fan revolution period +exceeds the limit value. Fan speed limit value is scaled by the +divisor setting for fan speed measurement. + + +An analog output provides a 0 to 1.25 volt signal intended for an external +fan speed amplifier circuit. The analog output is set to maximum value on +power up or reset. + + +Voltage (IN) measurement is internally scaled: + + nr label nominal maximum + mV mV + 0 +2.5V 2500 3320 + 1 Vccp1 2700 3600 + 2 +3.3V 3300 4380 + 3 +5V 5000 6640 + 4 +12V 12000 15940 + 5 Vccp2 2700 3600 + +The reading is an unsigned 8-bit value, nominal voltage measurement is +represented by a reading of 192, being 3/4 of the measurement range. + +An error is asserted for any voltage going below or above the set limits. + +The driver reports and accepts voltage limits scaled to the above table. + +The chip may also be used to measure negative voltages, usually on Vccp2. +In this case user-space tools will scale their readings based on the +maximum mV values from the table above and transpose the high and low +limit values. + + +Chassis Intrusion alarm is asserted when the CI pin goes active high. +The ADM9240 Datasheet has an example of an external temperature sensor +driving this pin. On an Intel SE440BX-2 the Chassis Intrusion header +is expected to be connected to a normally closed switch. + +The ADM9240 provides an internal open drain on this line, and may output +a 20 ms active low pulse to reset an external Chassis Intrusion latch. + +Chip differences +---------------- +ADM9240 has a very fast 320us temperature and voltage measurement cycle +with independent fan speed measurement cycles counting alternating rising +edges of the fan tacho inputs. Comparisons are described as "exceeds +limit." + +DS1780 measurement cycle is about once per second including fan speed. +"For the high limits of the voltages, the device is doing a greater than +comparison. For the low limits, however, it is doing a less than or equal +comparison." + +LM81 measurement cycle is about once per 400ms including fan speed, the +LM81 also has an unsupported 12-bit extended temperature measurement mode. +"For voltage input high limits, the device is doing a greater than comparison. +For low limits, however, it is doing a less than or equal to comparison." +
