Based on kernel version 2.6.26. Page generated on 2008-07-16 21:12 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 The ADT7463 has a THERM asserted counter. This counter has a 22.76ms 100 resolution and a range of 5.8 seconds. The driver implements a 32-bit 101 accumulator of the counter value to extend the range to over a year. The 102 counter will stay at it's max value until read. 103 104 See the vendor datasheets for more information. There is application note 105 from National (AN-1260) with some additional information about the LM85. 106 The Analog Devices datasheet is very detailed and describes a procedure for 107 determining an optimal configuration for the automatic PWM control. 108 109 The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and 110 fan speeds. They use this monitoring capability to alert the system to out 111 of limit conditions and can automatically control the speeds of multiple 112 fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP 113 package, and the EMC6D100, available in a 28-pin SSOP package, are designed 114 to be register compatible. The EMC6D100 offers all the features of the 115 EMC6D101 plus additional voltage monitoring and system control features. 116 Unfortunately it is not possible to distinguish between the package 117 versions on register level so these additional voltage inputs may read 118 zero. The EMC6D102 features addtional ADC bits thus extending precision 119 of voltage and temperature channels. 120 121 122 Hardware Configurations 123 ----------------------- 124 125 The LM85 can be jumpered for 3 different SMBus addresses. There are 126 no other hardware configuration options for the LM85. 127 128 The lm85 driver detects both LM85B and LM85C revisions of the chip. See the 129 datasheet for a complete description of the differences. Other than 130 identifying the chip, the driver behaves no differently with regard to 131 these two chips. The LM85B is recommended for new designs. 132 133 The ADM1027 and ADT7463 chips have an optional SMBALERT output that can be 134 used to signal the chipset in case a limit is exceeded or the temperature 135 sensors fail. Individual sensor interrupts can be masked so they won't 136 trigger SMBALERT. The SMBALERT output if configured replaces one of the other 137 functions (PWM2 or IN0). This functionality is not implemented in current 138 driver. 139 140 The ADT7463 also has an optional THERM output/input which can be connected 141 to the processor PROC_HOT output. If available, the autofan control 142 dynamic Tmin feature can be enabled to keep the system temperature within 143 spec (just?!) with the least possible fan noise. 144 145 Configuration Notes 146 ------------------- 147 148 Besides standard interfaces driver adds following: 149 150 * Temperatures and Zones 151 152 Each temperature sensor is associated with a Zone. There are three 153 sensors and therefore three zones (# 1, 2 and 3). Each zone has the following 154 temperature configuration points: 155 156 * temp#_auto_temp_off - temperature below which fans should be off or spinning very low. 157 * temp#_auto_temp_min - temperature over which fans start to spin. 158 * temp#_auto_temp_max - temperature when fans spin at full speed. 159 * temp#_auto_temp_crit - temperature when all fans will run full speed. 160 161 * PWM Control 162 163 There are three PWM outputs. The LM85 datasheet suggests that the 164 pwm3 output control both fan3 and fan4. Each PWM can be individually 165 configured and assigned to a zone for it's control value. Each PWM can be 166 configured individually according to the following options. 167 168 * pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off 169 temperature. (PWM value from 0 to 255) 170 171 * pwm#_auto_pwm_freq - select base frequency of PWM output. You can select 172 in range of 10.0 to 94.0 Hz in .1 Hz units. 173 (Values 100 to 940). 174 175 The pwm#_auto_pwm_freq can be set to one of the following 8 values. Setting the 176 frequency to a value not on this list, will result in the next higher frequency 177 being selected. The actual device frequency may vary slightly from this 178 specification as designed by the manufacturer. Consult the datasheet for more 179 details. (PWM Frequency values: 100, 150, 230, 300, 380, 470, 620, 940) 180 181 * pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature 182 the bahaviour of fans. Write 1 to let fans spinning at 183 pwm#_auto_pwm_min or write 0 to let them off. 184 185 NOTE: It has been reported that there is a bug in the LM85 that causes the flag 186 to be associated with the zones not the PWMs. This contradicts all the 187 published documentation. Setting pwm#_min_ctl in this case actually affects all 188 PWMs controlled by zone '#'. 189 190 * PWM Controlling Zone selection 191 192 * pwm#_auto_channels - controls zone that is associated with PWM 193 194 Configuration choices: 195 196 Value Meaning 197 ------ ------------------------------------------------ 198 1 Controlled by Zone 1 199 2 Controlled by Zone 2 200 3 Controlled by Zone 3 201 23 Controlled by higher temp of Zone 2 or 3 202 123 Controlled by highest temp of Zone 1, 2 or 3 203 0 PWM always 0% (off) 204 -1 PWM always 100% (full on) 205 -2 Manual control (write to 'pwm#' to set) 206 207 The National LM85's have two vendor specific configuration 208 features. Tach. mode and Spinup Control. For more details on these, 209 see the LM85 datasheet or Application Note AN-1260. 210 211 The Analog Devices ADM1027 has several vendor specific enhancements. 212 The number of pulses-per-rev of the fans can be set, Tach monitoring 213 can be optimized for PWM operation, and an offset can be applied to 214 the temperatures to compensate for systemic errors in the 215 measurements. 216 217 In addition to the ADM1027 features, the ADT7463 also has Tmin control 218 and THERM asserted counts. Automatic Tmin control acts to adjust the 219 Tmin value to maintain the measured temperature sensor at a specified 220 temperature. There isn't much documentation on this feature in the 221 ADT7463 data sheet. This is not supported by current driver.