Greetings, This patch adds adm9240 driver documentation, it is new file so does not interfere with Rudolf Marek's documentation series. Was partially reviewed earlier during driver development and is now updated to match the completed driver. --Grant. Signed-off-by: Grant Coady <gcoady at gmail.com> --- adm9240 | 214 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 214 insertions(+) diff -X dontdiff -Nrup linux-2.6.12-rc5-mm1/Documentation/i2c/chips/adm9240 linux-2.6.12-rc5-mm1a/Documentation/i2c/chips/adm9240 --- linux-2.6.12-rc5-mm1/Documentation/i2c/chips/adm9240 1970-01-01 10:00:00.000000000 +1000 +++ linux-2.6.12-rc5-mm1a/Documentation/i2c/chips/adm9240 2005-06-01 18:27:51.000000000 +1000 @@ -0,0 +1,214 @@ +Kernel driver adm9240 +===================== + +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://www.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/ + +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> + +Interface +========= +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. + +alarms R 16-bit alarm status +aout_output RW 0..1250mV analog output +chassis_clear W 'echo 1 > chassis_clear' to clear Chassis Intrusion latch +cpu0_vid R mV VID reading +fan1_div R 2 x fan divider, 1, 2, 4, 8 +fan1_input R 2 x fan speed reading in rpm +fan1_min RW 2 x fan minimum speed limit in rpm +in0_input R 6 x scaled voltage inputs [1] +in0_max RW 6 x voltage high limit +in0_min RW 6 x voltage low limit +temp1_input R chip temperature to 0.5'C resolution +temp1_max WR chip max temperature alarm point +temp1_max_hyst WR chip max temperature hysteresis [2] + +[1] Nominal mV: 2500, 2700, 3300, 5000, 12000, 2700 + +[2] temperature alarm asserted when temperature exceeds maximum value + and cleared when temperature falls below the hysteresis value + + +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. + +The ADM9240, DS1780 and LM81 are register compatible, the following +details are common to the three chips. Chip differences are described +after this section. + + +Measurements +============ +The measurement cycle + +The adm9240 driver will take a measurement reading no faster than once +each two seconds. User-space may read sysfs interface faster than the +measurement update rate and will receive cached data from the most +recent measurement. + +Temperature +----------- +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 default mode so that an alarm is asserted +once the temperature exceeds the high limit, and is cleared when the +temperature falls below the temp1_max_hyst value. + +Fan Speed +--------- +Two fan tacho inputs are provided, the ADM9240 gates an internal 22.5kHz +clock via a divider to an 8-bit counter. Fan speed (rpm) is calculated by: + +rpm = (22500 * 60) / (count * divider) + +Automatic fan clock divider + + * User sets 0 to fan_min limit + - low speed alarm is disabled + - fan clock divider not changed + - auto fan clock adjuster enabled for valid fan speed reading + + * User sets fan_min limit too low + - low speed alarm is enabled + - fan clock divider set to max + - fan_min set to register value 254 which corresponds + to 664 rpm on adm9240 + - low speed alarm will be asserted if fan speed is + less than minimum measurable speed + - auto fan clock adjuster disabled + + * User sets reasonable fan speed + - low speed alarm is enabled + - fan clock divider set to suit fan_min + - auto fan clock adjuster enabled: adjusts fan_min + + * User sets unreasonably high low fan speed limit + - resolution of the low speed limit may be reduced + - alarm will be asserted + - auto fan clock adjuster enabled: adjusts fan_min + + * fan speed may be displayed as zero until the auto fan clock divider + adjuster brings fan speed clock divider back into chip measurement + range, this will occur within a few measurement cycles. + +Note: changing the fan clock divider does NOT change the fan speed reading, +it adjusts the internal measurement range so that the 8-bit fan clock +counter does not overflow. The datasheet rpm values assume two pulses per +fan revolution. If your fan differs from two pulses per revolution, scale +the fan speed reading in user-space. + +Analog Output +------------- +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. This doesn't do much on the test Intel SE440BX-2. + +Voltage Monitor + +Voltage (IN) measurement is internally scaled: + + nr label nominal maximum resolution + mV mV mV + 0 +2.5V 2500 3320 13.0 + 1 Vccp1 2700 3600 14.1 + 2 +3.3V 3300 4380 17.2 + 3 +5V 5000 6640 26.0 + 4 +12V 12000 15940 62.5 + 5 Vccp2 2700 3600 14.1 + +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 alarm is asserted for any voltage going below or above the set limits. + +The driver reports and accepts voltage limits scaled to the above table. + +VID Monitor +----------- +The chip has five inputs to read the 5-bit VID and reports the mV value +based on detected CPU type. + +Chassis Intrusion +----------------- +An 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 +connected to a normally open 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. + +Clear the CI latch by writing value 1 to the sysfs chassis_clear file. + +Alarm flags reported as 16-bit word +----------------------------------- + bit label comment + ------ -------------- -------------------------------------------- + 0 +2.5 V_Error high or low limit exceeded + 1 VCCP_Error high or low limit exceeded + 2 +3.3 V_Error high or low limit exceeded + 3 +5 V_Error high or low limit exceeded + 4 Temp_Error temperature error + 6 FAN1_Error fan low limit exceeded + 7 FAN2_Error fan low limit exceeded + 8 +12 V_Error high or low limit exceeded + 9 VCCP2_Error high or low limit exceeded + 12 Chassis_Error CI pin went high + +Remaining bits are reserved and thus undefined. It is important to note +that alarm bits may be cleared on read, user-space may latch alarms and +provide the end-user with a method to clear alarm memory. + +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." + +Grant Coady <gcoady at gmail.com> 2005-05-31 +
