Based on kernel version 2.6.33. Page generated on 2010-02-24 15:36 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.analog.com/en/prod/0,,766_825_ADM1027,00.html 13 * Analog Devices ADT7463 14 Prefix: 'adt7463' 15 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 16 Datasheet: http://www.analog.com/en/prod/0,,766_825_ADT7463,00.html 17 * SMSC EMC6D100, SMSC EMC6D101 18 Prefix: 'emc6d100' 19 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 20 Datasheet: http://www.smsc.com/main/tools/discontinued/6d100.pdf 21 * SMSC EMC6D102 22 Prefix: 'emc6d102' 23 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 24 Datasheet: http://www.smsc.com/main/catalog/emc6d102.html 25 26 Authors: 27 Philip Pokorny <ppokorny[AT]penguincomputing[DOT]com>, 28 Frodo Looijaard <frodol[AT]dds[DOT]nl>, 29 Richard Barrington <rich_b_nz[AT]clear.net[DOT]nz>, 30 Margit Schubert-While <margitsw[AT]t-online[DOT]de>, 31 Justin Thiessen <jthiessen[AT]penguincomputing[DOT]com> 32 33 Description 34 ----------- 35 36 This driver implements support for the National Semiconductor LM85 and 37 compatible chips including the Analog Devices ADM1027, ADT7463 and 38 SMSC EMC6D10x chips family. 39 40 The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 41 specification. Using an analog to digital converter it measures three (3) 42 temperatures and five (5) voltages. It has four (4) 16-bit counters for 43 measuring fan speed. Five (5) digital inputs are provided for sampling the 44 VID signals from the processor to the VRM. Lastly, there are three (3) PWM 45 outputs that can be used to control fan speed. 46 47 The voltage inputs have internal scaling resistors so that the following 48 voltage can be measured without external resistors: 49 50 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V) 51 52 The temperatures measured are one internal diode, and two remote diodes. 53 Remote 1 is generally the CPU temperature. These inputs are designed to 54 measure a thermal diode like the one in a Pentium 4 processor in a socket 55 423 or socket 478 package. They can also measure temperature using a 56 transistor like the 2N3904. 57 58 A sophisticated control system for the PWM outputs is designed into the 59 LM85 that allows fan speed to be adjusted automatically based on any of the 60 three temperature sensors. Each PWM output is individually adjustable and 61 programmable. Once configured, the LM85 will adjust the PWM outputs in 62 response to the measured temperatures without further host intervention. 63 This feature can also be disabled for manual control of the PWM's. 64 65 Each of the measured inputs (voltage, temperature, fan speed) has 66 corresponding high/low limit values. The LM85 will signal an ALARM if any 67 measured value exceeds either limit. 68 69 The LM85 samples all inputs continuously. The lm85 driver will not read 70 the registers more often than once a second. Further, configuration data is 71 only read once each 5 minutes. There is twice as much config data as 72 measurements, so this would seem to be a worthwhile optimization. 73 74 Special Features 75 ---------------- 76 77 The LM85 has four fan speed monitoring modes. The ADM1027 has only two. 78 Both have special circuitry to compensate for PWM interactions with the 79 TACH signal from the fans. The ADM1027 can be configured to measure the 80 speed of a two wire fan, but the input conditioning circuitry is different 81 for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not 82 exposed to user control. The BIOS should initialize them to the correct 83 mode. If you've designed your own ADM1027, you'll have to modify the 84 init_client function and add an insmod parameter to set this up. 85 86 To smooth the response of fans to changes in temperature, the LM85 has an 87 optional filter for smoothing temperatures. The ADM1027 has the same 88 config option but uses it to rate limit the changes to fan speed instead. 89 90 The ADM1027 and ADT7463 have a 10-bit ADC and can therefore measure 91 temperatures with 0.25 degC resolution. They also provide an offset to the 92 temperature readings that is automatically applied during measurement. 93 This offset can be used to zero out any errors due to traces and placement. 94 The documentation says that the offset is in 0.25 degC steps, but in 95 initial testing of the ADM1027 it was 1.00 degC steps. Analog Devices has 96 confirmed this "bug". The ADT7463 is reported to work as described in the 97 documentation. The current lm85 driver does not show the offset register. 98 99 See the vendor datasheets for more information. There is application note 100 from National (AN-1260) with some additional information about the LM85. 101 The Analog Devices datasheet is very detailed and describes a procedure for 102 determining an optimal configuration for the automatic PWM control. 103 104 The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and 105 fan speeds. They use this monitoring capability to alert the system to out 106 of limit conditions and can automatically control the speeds of multiple 107 fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP 108 package, and the EMC6D100, available in a 28-pin SSOP package, are designed 109 to be register compatible. The EMC6D100 offers all the features of the 110 EMC6D101 plus additional voltage monitoring and system control features. 111 Unfortunately it is not possible to distinguish between the package 112 versions on register level so these additional voltage inputs may read 113 zero. The EMC6D102 features addtional ADC bits thus extending precision 114 of voltage and temperature channels. 115 116 117 Hardware Configurations 118 ----------------------- 119 120 The LM85 can be jumpered for 3 different SMBus addresses. There are 121 no other hardware configuration options for the LM85. 122 123 The lm85 driver detects both LM85B and LM85C revisions of the chip. See the 124 datasheet for a complete description of the differences. Other than 125 identifying the chip, the driver behaves no differently with regard to 126 these two chips. The LM85B is recommended for new designs. 127 128 The ADM1027 and ADT7463 chips have an optional SMBALERT output that can be 129 used to signal the chipset in case a limit is exceeded or the temperature 130 sensors fail. Individual sensor interrupts can be masked so they won't 131 trigger SMBALERT. The SMBALERT output if configured replaces one of the other 132 functions (PWM2 or IN0). This functionality is not implemented in current 133 driver. 134 135 The ADT7463 also has an optional THERM output/input which can be connected 136 to the processor PROC_HOT output. If available, the autofan control 137 dynamic Tmin feature can be enabled to keep the system temperature within 138 spec (just?!) with the least possible fan noise. 139 140 Configuration Notes 141 ------------------- 142 143 Besides standard interfaces driver adds following: 144 145 * Temperatures and Zones 146 147 Each temperature sensor is associated with a Zone. There are three 148 sensors and therefore three zones (# 1, 2 and 3). Each zone has the following 149 temperature configuration points: 150 151 * temp#_auto_temp_off - temperature below which fans should be off or spinning very low. 152 * temp#_auto_temp_min - temperature over which fans start to spin. 153 * temp#_auto_temp_max - temperature when fans spin at full speed. 154 * temp#_auto_temp_crit - temperature when all fans will run full speed. 155 156 * PWM Control 157 158 There are three PWM outputs. The LM85 datasheet suggests that the 159 pwm3 output control both fan3 and fan4. Each PWM can be individually 160 configured and assigned to a zone for it's control value. Each PWM can be 161 configured individually according to the following options. 162 163 * pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off 164 temperature. (PWM value from 0 to 255) 165 166 * pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature 167 the behaviour of fans. Write 1 to let fans spinning at 168 pwm#_auto_pwm_min or write 0 to let them off. 169 170 NOTE: It has been reported that there is a bug in the LM85 that causes the flag 171 to be associated with the zones not the PWMs. This contradicts all the 172 published documentation. Setting pwm#_min_ctl in this case actually affects all 173 PWMs controlled by zone '#'. 174 175 * PWM Controlling Zone selection 176 177 * pwm#_auto_channels - controls zone that is associated with PWM 178 179 Configuration choices: 180 181 Value Meaning 182 ------ ------------------------------------------------ 183 1 Controlled by Zone 1 184 2 Controlled by Zone 2 185 3 Controlled by Zone 3 186 23 Controlled by higher temp of Zone 2 or 3 187 123 Controlled by highest temp of Zone 1, 2 or 3 188 0 PWM always 0% (off) 189 -1 PWM always 100% (full on) 190 -2 Manual control (write to 'pwm#' to set) 191 192 The National LM85's have two vendor specific configuration 193 features. Tach. mode and Spinup Control. For more details on these, 194 see the LM85 datasheet or Application Note AN-1260. These features 195 are not currently supported by the lm85 driver. 196 197 The Analog Devices ADM1027 has several vendor specific enhancements. 198 The number of pulses-per-rev of the fans can be set, Tach monitoring 199 can be optimized for PWM operation, and an offset can be applied to 200 the temperatures to compensate for systemic errors in the 201 measurements. These features are not currently supported by the lm85 202 driver. 203 204 In addition to the ADM1027 features, the ADT7463 also has Tmin control 205 and THERM asserted counts. Automatic Tmin control acts to adjust the 206 Tmin value to maintain the measured temperature sensor at a specified 207 temperature. There isn't much documentation on this feature in the 208 ADT7463 data sheet. This is not supported by current driver.