| Guenter Roeck | 9de2e2e | 2012-05-20 19:29:48 -0700 | [diff] [blame] | 1 | Note |
| 2 | ==== |
| 3 | |
| 4 | This driver supersedes the NCT6775F and NCT6776F support in the W83627EHF |
| 5 | driver. |
| 6 | |
| 7 | Kernel driver NCT6775 |
| 8 | ===================== |
| 9 | |
| 10 | Supported chips: |
| 11 | * Nuvoton NCT6775F/W83667HG-I |
| 12 | Prefix: 'nct6775' |
| 13 | Addresses scanned: ISA address retrieved from Super I/O registers |
| 14 | Datasheet: Available from Nuvoton upon request |
| 15 | * Nuvoton NCT6776F |
| 16 | Prefix: 'nct6776' |
| 17 | Addresses scanned: ISA address retrieved from Super I/O registers |
| 18 | Datasheet: Available from Nuvoton upon request |
| 19 | * Nuvoton NCT6779D |
| 20 | Prefix: 'nct6779' |
| 21 | Addresses scanned: ISA address retrieved from Super I/O registers |
| 22 | Datasheet: Available from Nuvoton upon request |
| 23 | |
| 24 | Authors: |
| 25 | Guenter Roeck <linux@roeck-us.net> |
| 26 | |
| 27 | Description |
| 28 | ----------- |
| 29 | |
| 30 | This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D |
| 31 | super I/O chips. |
| 32 | |
| 33 | The chips support up to 25 temperature monitoring sources. Up to 6 of those are |
| 34 | direct temperature sensor inputs, the others are special sources such as PECI, |
| 35 | PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources |
| 36 | can be monitored and compared against minimum, maximum, and critical |
| 37 | temperatures. The driver reports up to 10 of the temperatures to the user. |
| 38 | There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors, |
| 39 | one VID, alarms with beep warnings (control unimplemented), and some automatic |
| 40 | fan regulation strategies (plus manual fan control mode). |
| 41 | |
| 42 | The temperature sensor sources on all chips are configurable. The configured |
| 43 | source for each of the temperature sensors is provided in tempX_label. |
| 44 | |
| 45 | Temperatures are measured in degrees Celsius and measurement resolution is |
| 46 | either 1 degC or 0.5 degC, depending on the temperature source and |
| 47 | configuration. An alarm is triggered when the temperature gets higher than |
| 48 | the high limit; it stays on until the temperature falls below the hysteresis |
| 49 | value. Alarms are only supported for temp1 to temp6, depending on the chip type. |
| 50 | |
| 51 | Fan rotation speeds are reported in RPM (rotations per minute). An alarm is |
| 52 | triggered if the rotation speed has dropped below a programmable limit. On |
| 53 | NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8, |
| 54 | 16, 32, 64 or 128) to give the readings more range or accuracy; the other chips |
| 55 | do not have a fan speed divider. The driver sets the most suitable fan divisor |
| Guenter Roeck | 1c65dc3 | 2012-12-04 07:56:24 -0800 | [diff] [blame] | 56 | itself; specifically, it increases the divider value each time a fan speed |
| 57 | reading returns an invalid value, and it reduces it if the fan speed reading |
| 58 | is lower than optimal. Some fans might not be present because they share pins |
| Guenter Roeck | 9de2e2e | 2012-05-20 19:29:48 -0700 | [diff] [blame] | 59 | with other functions. |
| 60 | |
| 61 | Voltage sensors (also known as IN sensors) report their values in millivolts. |
| 62 | An alarm is triggered if the voltage has crossed a programmable minimum |
| 63 | or maximum limit. |
| 64 | |
| 65 | The driver supports automatic fan control mode known as Thermal Cruise. |
| 66 | In this mode, the chip attempts to keep the measured temperature in a |
| 67 | predefined temperature range. If the temperature goes out of range, fan |
| 68 | is driven slower/faster to reach the predefined range again. |
| 69 | |
| 70 | The mode works for fan1-fan5. |
| 71 | |
| Guenter Roeck | 77eb5b3 | 2012-12-04 08:30:54 -0800 | [diff] [blame^] | 72 | sysfs attributes |
| 73 | ---------------- |
| 74 | |
| 75 | pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range: |
| 76 | 0 (lowest speed) to 255 (full) |
| 77 | |
| 78 | pwm[1-5]_enable - this file controls mode of fan/temperature control: |
| 79 | * 0 Fan control disabled (fans set to maximum speed) |
| 80 | * 1 Manual mode, write to pwm[0-5] any value 0-255 |
| 81 | * 2 "Thermal Cruise" mode |
| 82 | * 3 "Fan Speed Cruise" mode |
| 83 | * 4 "Smart Fan III" mode (NCT6775F only) |
| 84 | * 5 "Smart Fan IV" mode |
| 85 | |
| 86 | pwm[1-5]_mode - controls if output is PWM or DC level |
| 87 | * 0 DC output |
| 88 | * 1 PWM output |
| 89 | |
| Guenter Roeck | 9de2e2e | 2012-05-20 19:29:48 -0700 | [diff] [blame] | 90 | Usage Notes |
| 91 | ----------- |
| 92 | |
| 93 | On various ASUS boards with NCT6776F, it appears that CPUTIN is not really |
| 94 | connected to anything and floats, or that it is connected to some non-standard |
| 95 | temperature measurement device. As a result, the temperature reported on CPUTIN |
| 96 | will not reflect a usable value. It often reports unreasonably high |
| 97 | temperatures, and in some cases the reported temperature declines if the actual |
| 98 | temperature increases (similar to the raw PECI temperature value - see PECI |
| 99 | specification for details). CPUTIN should therefore be be ignored on ASUS |
| 100 | boards. The CPU temperature on ASUS boards is reported from PECI 0. |