From 72f3e7ae90d598cfab849c50cc721f52fad4abc5 Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Sun, 11 Mar 2012 14:47:57 -0700 Subject: [PATCH] Add README Signed-off-by: Guenter Roeck --- README | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 README diff --git a/README b/README new file mode 100644 index 0000000..5fedbca --- /dev/null +++ b/README @@ -0,0 +1,124 @@ +Note +==== + +This driver is experimental and has only been tested on NCT6775F. + +This driver supercedes the NCT6775F and NCT6776F support in the W83627EHF +driver. + +Kernel driver NCT6775 +======================= + +Supported chips: + * Nuvoton NCT6775F/W83667HG-I + Prefix: 'nct6775' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: Available from Nuvoton upon request + * Nuvoton NCT6776F + Prefix: 'nct6776' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: Available from Nuvoton upon request + * Nuvoton NCT6779D + Prefix: 'nct6776' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: Available from Nuvoton upon request + +Authors: + Guenter Roeck + +Description +----------- + +This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D +super I/O chips. We will refer to them collectively as Nuvoton chips. + +The chips implement 2 to 4 temperature sensors (9 for NCT6775F and NCT6776F), +2 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors, one VID, +alarms with beep warnings (control unimplemented), and some automatic fan +regulation strategies (plus manual fan control mode). + +The temperature sensor sources on all chips are configurable. temp4 and higher +attributes are only reported if its temperature source differs from the +temperature sources of the already reported temperature sensors. +The configured source for each of the temperature sensors is provided +in tempX_label. + +Temperatures are measured in degrees Celsius and measurement resolution is 1 +degC for temp1 and and 0.5 degC for temp2 and temp3. For temp4 and higher, +resolution is 1 degC for W83667HG-B and 0.5 degC for NCT6775F and NCT6776F. +An alarm is triggered when the temperature gets higher than high limit; +it stays on until the temperature falls below the hysteresis value. +Alarms are only supported for temp1, temp2, and temp3. + +Fan rotation speeds are reported in RPM (rotations per minute). An alarm is +triggered if the rotation speed has dropped below a programmable limit. Fan +readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or +128) to give the readings more range or accuracy. The driver sets the most +suitable fan divisor itself. Some fans might not be present because they +share pins with other functions. + +Voltage sensors (also known as IN sensors) report their values in millivolts. +An alarm is triggered if the voltage has crossed a programmable minimum +or maximum limit. + +The driver supports automatic fan control mode known as Thermal Cruise. +In this mode, the chip attempts to keep the measured temperature in a +predefined temperature range. If the temperature goes out of range, fan +is driven slower/faster to reach the predefined range again. + +The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as +follows: + +temp1 -> pwm1 +temp2 -> pwm2 +temp3 -> pwm3 + +/sys files +---------- + +name - this is a standard hwmon device entry, it contains the name of + the device (see the prefix in the list of supported devices at + the top of this file) + +pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range: + 0 (stop) to 255 (full) + +pwm[1-5]_enable - this file controls mode of fan/temperature control: + * 1 Manual mode, write to pwm file any value 0-255 (full speed) + * 2 "Thermal Cruise" mode + * 3 "Fan Speed Cruise" mode + * 4 "Smart Fan III" mode + * 5 "Smart Fan IV" mode + + SmartFan III mode is not supported on NCT6776F and NCT6779D. + +pwm[1-5]_mode - controls if output is PWM or DC level + * 0 DC output (0 - 12v) + * 1 PWM output + +Thermal Cruise mode +------------------- + +If the temperature is in the range defined by: + +pwm[1-4]_target - set target temperature, unit millidegree Celsius + (range 0 - 127000) +pwm[1-4]_tolerance - tolerance, unit millidegree Celsius (range 0 - 15000) + +There are no changes to fan speed. Once the temperature leaves the interval, +fan speed increases (temp is higher) or decreases if lower than desired. +There are defined steps and times, but not exported by the driver yet. + +pwm[1-4]_min_output - minimum fan speed (range 1 - 255), when the temperature + is below defined range. +pwm[1-4]_stop_time - how many milliseconds [ms] must elapse to switch + corresponding fan off. (when the temperature was below + defined range). + +Note: last two functions are influenced by other control bits, not yet exported + by the driver, so a change might not have any effect. + +Implementation Details +---------------------- + +TBD -- 2.39.5