Based on kernel version 3.9. Page generated on 2013-05-02 23:07 EST.
1 Kernel driver lm85 2 ================== 3 4 Supported chips: 5 * National Semiconductor LM85 (B and C versions) 6 Prefix: 'lm85' 7 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 8 Datasheet: http://www.national.com/pf/LM/LM85.html 9 * Analog Devices ADM1027 10 Prefix: 'adm1027' 11 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 12 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADM1027 13 * Analog Devices ADT7463 14 Prefix: 'adt7463' 15 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 16 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7463 17 * Analog Devices ADT7468 18 Prefix: 'adt7468' 19 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 20 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7468 21 * SMSC EMC6D100, SMSC EMC6D101 22 Prefix: 'emc6d100' 23 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 24 Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf 25 * SMSC EMC6D102 26 Prefix: 'emc6d102' 27 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 28 Datasheet: http://www.smsc.com/main/catalog/emc6d102.html 29 * SMSC EMC6D103 30 Prefix: 'emc6d103' 31 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 32 Datasheet: http://www.smsc.com/main/catalog/emc6d103.html 33 * SMSC EMC6D103S 34 Prefix: 'emc6d103s' 35 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 36 Datasheet: http://www.smsc.com/main/catalog/emc6d103s.html 37 38 Authors: 39 Philip Pokorny <email@example.com>, 40 Frodo Looijaard <firstname.lastname@example.org>, 41 Richard Barrington <email@example.com>, 42 Margit Schubert-While <firstname.lastname@example.org>, 43 Justin Thiessen <email@example.com> 44 45 Description 46 ----------- 47 48 This driver implements support for the National Semiconductor LM85 and 49 compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and 50 SMSC EMC6D10x chips family. 51 52 The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 53 specification. Using an analog to digital converter it measures three (3) 54 temperatures and five (5) voltages. It has four (4) 16-bit counters for 55 measuring fan speed. Five (5) digital inputs are provided for sampling the 56 VID signals from the processor to the VRM. Lastly, there are three (3) PWM 57 outputs that can be used to control fan speed. 58 59 The voltage inputs have internal scaling resistors so that the following 60 voltage can be measured without external resistors: 61 62 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V) 63 64 The temperatures measured are one internal diode, and two remote diodes. 65 Remote 1 is generally the CPU temperature. These inputs are designed to 66 measure a thermal diode like the one in a Pentium 4 processor in a socket 67 423 or socket 478 package. They can also measure temperature using a 68 transistor like the 2N3904. 69 70 A sophisticated control system for the PWM outputs is designed into the 71 LM85 that allows fan speed to be adjusted automatically based on any of the 72 three temperature sensors. Each PWM output is individually adjustable and 73 programmable. Once configured, the LM85 will adjust the PWM outputs in 74 response to the measured temperatures without further host intervention. 75 This feature can also be disabled for manual control of the PWM's. 76 77 Each of the measured inputs (voltage, temperature, fan speed) has 78 corresponding high/low limit values. The LM85 will signal an ALARM if any 79 measured value exceeds either limit. 80 81 The LM85 samples all inputs continuously. The lm85 driver will not read 82 the registers more often than once a second. Further, configuration data is 83 only read once each 5 minutes. There is twice as much config data as 84 measurements, so this would seem to be a worthwhile optimization. 85 86 Special Features 87 ---------------- 88 89 The LM85 has four fan speed monitoring modes. The ADM1027 has only two. 90 Both have special circuitry to compensate for PWM interactions with the 91 TACH signal from the fans. The ADM1027 can be configured to measure the 92 speed of a two wire fan, but the input conditioning circuitry is different 93 for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not 94 exposed to user control. The BIOS should initialize them to the correct 95 mode. If you've designed your own ADM1027, you'll have to modify the 96 init_client function and add an insmod parameter to set this up. 97 98 To smooth the response of fans to changes in temperature, the LM85 has an 99 optional filter for smoothing temperatures. The ADM1027 has the same 100 config option but uses it to rate limit the changes to fan speed instead. 101 102 The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore 103 measure temperatures with 0.25 degC resolution. They also provide an offset 104 to the temperature readings that is automatically applied during 105 measurement. This offset can be used to zero out any errors due to traces 106 and placement. The documentation says that the offset is in 0.25 degC 107 steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog 108 Devices has confirmed this "bug". The ADT7463 is reported to work as 109 described in the documentation. The current lm85 driver does not show the 110 offset register. 111 112 The ADT7468 has a high-frequency PWM mode, where all PWM outputs are 113 driven by a 22.5 kHz clock. This is a global mode, not per-PWM output, 114 which means that setting any PWM frequency above 11.3 kHz will switch 115 all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM 116 frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency 117 between 10 and 100 Hz, which can then be tuned separately. 118 119 See the vendor datasheets for more information. There is application note 120 from National (AN-1260) with some additional information about the LM85. 121 The Analog Devices datasheet is very detailed and describes a procedure for 122 determining an optimal configuration for the automatic PWM control. 123 124 The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and 125 fan speeds. They use this monitoring capability to alert the system to out 126 of limit conditions and can automatically control the speeds of multiple 127 fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP 128 package, and the EMC6D100, available in a 28-pin SSOP package, are designed 129 to be register compatible. The EMC6D100 offers all the features of the 130 EMC6D101 plus additional voltage monitoring and system control features. 131 Unfortunately it is not possible to distinguish between the package 132 versions on register level so these additional voltage inputs may read 133 zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision 134 of voltage and temperature channels. 135 136 SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl 137 and temp#_auto_temp_off. 138 139 Hardware Configurations 140 ----------------------- 141 142 The LM85 can be jumpered for 3 different SMBus addresses. There are 143 no other hardware configuration options for the LM85. 144 145 The lm85 driver detects both LM85B and LM85C revisions of the chip. See the 146 datasheet for a complete description of the differences. Other than 147 identifying the chip, the driver behaves no differently with regard to 148 these two chips. The LM85B is recommended for new designs. 149 150 The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output 151 that can be used to signal the chipset in case a limit is exceeded or the 152 temperature sensors fail. Individual sensor interrupts can be masked so 153 they won't trigger SMBALERT. The SMBALERT output if configured replaces one 154 of the other functions (PWM2 or IN0). This functionality is not implemented 155 in current driver. 156 157 The ADT7463 and ADT7468 also have an optional THERM output/input which can 158 be connected to the processor PROC_HOT output. If available, the autofan 159 control dynamic Tmin feature can be enabled to keep the system temperature 160 within spec (just?!) with the least possible fan noise. 161 162 Configuration Notes 163 ------------------- 164 165 Besides standard interfaces driver adds following: 166 167 * Temperatures and Zones 168 169 Each temperature sensor is associated with a Zone. There are three 170 sensors and therefore three zones (# 1, 2 and 3). Each zone has the following 171 temperature configuration points: 172 173 * temp#_auto_temp_off - temperature below which fans should be off or spinning very low. 174 * temp#_auto_temp_min - temperature over which fans start to spin. 175 * temp#_auto_temp_max - temperature when fans spin at full speed. 176 * temp#_auto_temp_crit - temperature when all fans will run full speed. 177 178 * PWM Control 179 180 There are three PWM outputs. The LM85 datasheet suggests that the 181 pwm3 output control both fan3 and fan4. Each PWM can be individually 182 configured and assigned to a zone for its control value. Each PWM can be 183 configured individually according to the following options. 184 185 * pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off 186 temperature. (PWM value from 0 to 255) 187 188 * pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature 189 the behaviour of fans. Write 1 to let fans spinning at 190 pwm#_auto_pwm_min or write 0 to let them off. 191 192 NOTE: It has been reported that there is a bug in the LM85 that causes the flag 193 to be associated with the zones not the PWMs. This contradicts all the 194 published documentation. Setting pwm#_min_ctl in this case actually affects all 195 PWMs controlled by zone '#'. 196 197 * PWM Controlling Zone selection 198 199 * pwm#_auto_channels - controls zone that is associated with PWM 200 201 Configuration choices: 202 203 Value Meaning 204 ------ ------------------------------------------------ 205 1 Controlled by Zone 1 206 2 Controlled by Zone 2 207 3 Controlled by Zone 3 208 23 Controlled by higher temp of Zone 2 or 3 209 123 Controlled by highest temp of Zone 1, 2 or 3 210 0 PWM always 0% (off) 211 -1 PWM always 100% (full on) 212 -2 Manual control (write to 'pwm#' to set) 213 214 The National LM85's have two vendor specific configuration 215 features. Tach. mode and Spinup Control. For more details on these, 216 see the LM85 datasheet or Application Note AN-1260. These features 217 are not currently supported by the lm85 driver. 218 219 The Analog Devices ADM1027 has several vendor specific enhancements. 220 The number of pulses-per-rev of the fans can be set, Tach monitoring 221 can be optimized for PWM operation, and an offset can be applied to 222 the temperatures to compensate for systemic errors in the 223 measurements. These features are not currently supported by the lm85 224 driver. 225 226 In addition to the ADM1027 features, the ADT7463 and ADT7468 also have 227 Tmin control and THERM asserted counts. Automatic Tmin control acts to 228 adjust the Tmin value to maintain the measured temperature sensor at a 229 specified temperature. There isn't much documentation on this feature in 230 the ADT7463 data sheet. This is not supported by current driver.