1Note 2==== 3 4This driver supersedes the NCT6775F and NCT6776F support in the W83627EHF 5driver. 6 7Kernel driver NCT6775 8===================== 9 10Supported chips: 11 * Nuvoton NCT6102D/NCT6104D/NCT6106D 12 Prefix: 'nct6106' 13 Addresses scanned: ISA address retrieved from Super I/O registers 14 Datasheet: Available from the Nuvoton web site 15 * Nuvoton NCT5572D/NCT6771F/NCT6772F/NCT6775F/W83677HG-I 16 Prefix: 'nct6775' 17 Addresses scanned: ISA address retrieved from Super I/O registers 18 Datasheet: Available from Nuvoton upon request 19 * Nuvoton NCT5573D/NCT5577D/NCT6776D/NCT6776F 20 Prefix: 'nct6776' 21 Addresses scanned: ISA address retrieved from Super I/O registers 22 Datasheet: Available from Nuvoton upon request 23 * Nuvoton NCT5532D/NCT6779D 24 Prefix: 'nct6779' 25 Addresses scanned: ISA address retrieved from Super I/O registers 26 Datasheet: Available from Nuvoton upon request 27 * Nuvoton NCT6791D 28 Prefix: 'nct6791' 29 Addresses scanned: ISA address retrieved from Super I/O registers 30 Datasheet: Available from Nuvoton upon request 31 * Nuvoton NCT6792D 32 Prefix: 'nct6792' 33 Addresses scanned: ISA address retrieved from Super I/O registers 34 Datasheet: Available from Nuvoton upon request 35 * Nuvoton NCT6793D 36 Prefix: 'nct6793' 37 Addresses scanned: ISA address retrieved from Super I/O registers 38 Datasheet: Available from Nuvoton upon request 39 * Nuvoton NCT6795D 40 Prefix: 'nct6795' 41 Addresses scanned: ISA address retrieved from Super I/O registers 42 Datasheet: Available from Nuvoton upon request 43 * Nuvoton NCT6796D 44 Prefix: 'nct6796' 45 Addresses scanned: ISA address retrieved from Super I/O registers 46 Datasheet: Available from Nuvoton upon request 47 48Authors: 49 Guenter Roeck <linux@roeck-us.net> 50 51Description 52----------- 53 54This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D 55and compatible super I/O chips. 56 57The chips support up to 25 temperature monitoring sources. Up to 6 of those are 58direct temperature sensor inputs, the others are special sources such as PECI, 59PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources 60can be monitored and compared against minimum, maximum, and critical 61temperatures. The driver reports up to 10 of the temperatures to the user. 62There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors, 63one VID, alarms with beep warnings (control unimplemented), and some automatic 64fan regulation strategies (plus manual fan control mode). 65 66The temperature sensor sources on all chips are configurable. The configured 67source for each of the temperature sensors is provided in tempX_label. 68 69Temperatures are measured in degrees Celsius and measurement resolution is 70either 1 degC or 0.5 degC, depending on the temperature source and 71configuration. An alarm is triggered when the temperature gets higher than 72the high limit; it stays on until the temperature falls below the hysteresis 73value. Alarms are only supported for temp1 to temp6, depending on the chip type. 74 75Fan rotation speeds are reported in RPM (rotations per minute). An alarm is 76triggered if the rotation speed has dropped below a programmable limit. On 77NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8, 7816, 32, 64 or 128) to give the readings more range or accuracy; the other chips 79do not have a fan speed divider. The driver sets the most suitable fan divisor 80itself; specifically, it increases the divider value each time a fan speed 81reading returns an invalid value, and it reduces it if the fan speed reading 82is lower than optimal. Some fans might not be present because they share pins 83with other functions. 84 85Voltage sensors (also known as IN sensors) report their values in millivolts. 86An alarm is triggered if the voltage has crossed a programmable minimum 87or maximum limit. 88 89The driver supports automatic fan control mode known as Thermal Cruise. 90In this mode, the chip attempts to keep the measured temperature in a 91predefined temperature range. If the temperature goes out of range, fan 92is driven slower/faster to reach the predefined range again. 93 94The mode works for fan1-fan5. 95 96sysfs attributes 97---------------- 98 99pwm[1-7] - this file stores PWM duty cycle or DC value (fan speed) in range: 100 0 (lowest speed) to 255 (full) 101 102pwm[1-7]_enable - this file controls mode of fan/temperature control: 103 * 0 Fan control disabled (fans set to maximum speed) 104 * 1 Manual mode, write to pwm[0-5] any value 0-255 105 * 2 "Thermal Cruise" mode 106 * 3 "Fan Speed Cruise" mode 107 * 4 "Smart Fan III" mode (NCT6775F only) 108 * 5 "Smart Fan IV" mode 109 110pwm[1-7]_mode - controls if output is PWM or DC level 111 * 0 DC output 112 * 1 PWM output 113 114Common fan control attributes 115----------------------------- 116 117pwm[1-7]_temp_sel Temperature source. Value is temperature sensor index. 118 For example, select '1' for temp1_input. 119pwm[1-7]_weight_temp_sel 120 Secondary temperature source. Value is temperature 121 sensor index. For example, select '1' for temp1_input. 122 Set to 0 to disable secondary temperature control. 123 124If secondary temperature functionality is enabled, it is controlled with the 125following attributes. 126 127pwm[1-7]_weight_duty_step 128 Duty step size. 129pwm[1-7]_weight_temp_step 130 Temperature step size. With each step over 131 temp_step_base, the value of weight_duty_step is added 132 to the current pwm value. 133pwm[1-7]_weight_temp_step_base 134 Temperature at which secondary temperature control kicks 135 in. 136pwm[1-7]_weight_temp_step_tol 137 Temperature step tolerance. 138 139Thermal Cruise mode (2) 140----------------------- 141 142If the temperature is in the range defined by: 143 144pwm[1-7]_target_temp Target temperature, unit millidegree Celsius 145 (range 0 - 127000) 146pwm[1-7]_temp_tolerance 147 Target temperature tolerance, unit millidegree Celsius 148 149there are no changes to fan speed. Once the temperature leaves the interval, fan 150speed increases (if temperature is higher that desired) or decreases (if 151temperature is lower than desired), using the following limits and time 152intervals. 153 154pwm[1-7]_start fan pwm start value (range 1 - 255), to start fan 155 when the temperature is above defined range. 156pwm[1-7]_floor lowest fan pwm (range 0 - 255) if temperature is below 157 the defined range. If set to 0, the fan is expected to 158 stop if the temperature is below the defined range. 159pwm[1-7]_step_up_time milliseconds before fan speed is increased 160pwm[1-7]_step_down_time milliseconds before fan speed is decreased 161pwm[1-7]_stop_time how many milliseconds must elapse to switch 162 corresponding fan off (when the temperature was below 163 defined range). 164 165Speed Cruise mode (3) 166--------------------- 167 168This modes tries to keep the fan speed constant. 169 170fan[1-7]_target Target fan speed 171fan[1-7]_tolerance 172 Target speed tolerance 173 174 175Untested; use at your own risk. 176 177Smart Fan IV mode (5) 178--------------------- 179 180This mode offers multiple slopes to control the fan speed. The slopes can be 181controlled by setting the pwm and temperature attributes. When the temperature 182rises, the chip will calculate the DC/PWM output based on the current slope. 183There are up to seven data points depending on the chip type. Subsequent data 184points should be set to higher temperatures and higher pwm values to achieve 185higher fan speeds with increasing temperature. The last data point reflects 186critical temperature mode, in which the fans should run at full speed. 187 188pwm[1-7]_auto_point[1-7]_pwm 189 pwm value to be set if temperature reaches matching 190 temperature range. 191pwm[1-7]_auto_point[1-7]_temp 192 Temperature over which the matching pwm is enabled. 193pwm[1-7]_temp_tolerance 194 Temperature tolerance, unit millidegree Celsius 195pwm[1-7]_crit_temp_tolerance 196 Temperature tolerance for critical temperature, 197 unit millidegree Celsius 198 199pwm[1-7]_step_up_time milliseconds before fan speed is increased 200pwm[1-7]_step_down_time milliseconds before fan speed is decreased 201 202Usage Notes 203----------- 204 205On various ASUS boards with NCT6776F, it appears that CPUTIN is not really 206connected to anything and floats, or that it is connected to some non-standard 207temperature measurement device. As a result, the temperature reported on CPUTIN 208will not reflect a usable value. It often reports unreasonably high 209temperatures, and in some cases the reported temperature declines if the actual 210temperature increases (similar to the raw PECI temperature value - see PECI 211specification for details). CPUTIN should therefore be be ignored on ASUS 212boards. The CPU temperature on ASUS boards is reported from PECI 0. 213
