1 Kernel driver lm85 2 ================== 3 4 Supported chips: 5 6 * National Semiconductor LM85 (B and C versions) 7 8 Prefix: 'lm85b' or 'lm85c' 9 10 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 11 12 Datasheet: http://www.national.com/pf/LM/LM85.html 13 14 * Texas Instruments LM96000 15 16 Prefix: 'lm9600' 17 18 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 19 20 Datasheet: https://www.ti.com/lit/ds/symlink/lm96000.pdf 21 22 * Analog Devices ADM1027 23 24 Prefix: 'adm1027' 25 26 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 27 28 Datasheet: https://www.onsemi.com/PowerSolutions/product.do?id=ADM1027 29 30 * Analog Devices ADT7463 31 32 Prefix: 'adt7463' 33 34 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 35 36 Datasheet: https://www.onsemi.com/PowerSolutions/product.do?id=ADT7463 37 38 * Analog Devices ADT7468 39 40 Prefix: 'adt7468' 41 42 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 43 44 Datasheet: https://www.onsemi.com/PowerSolutions/product.do?id=ADT7468 45 46 * SMSC EMC6D100, SMSC EMC6D101 47 48 Prefix: 'emc6d100' 49 50 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 51 52 Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf 53 54 * SMSC EMC6D102 55 56 Prefix: 'emc6d102' 57 58 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 59 60 Datasheet: http://www.smsc.com/main/catalog/emc6d102.html 61 62 * SMSC EMC6D103 63 64 Prefix: 'emc6d103' 65 66 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 67 68 Datasheet: http://www.smsc.com/main/catalog/emc6d103.html 69 70 * SMSC EMC6D103S 71 72 Prefix: 'emc6d103s' 73 74 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 75 76 Datasheet: http://www.smsc.com/main/catalog/emc6d103s.html 77 78 Authors: 79 - Philip Pokorny <ppokorny@penguincomputing.com>, 80 - Frodo Looijaard <frodol@dds.nl>, 81 - Richard Barrington <rich_b_nz@clear.net.nz>, 82 - Margit Schubert-While <margitsw@t-online.de>, 83 - Justin Thiessen <jthiessen@penguincomputing.com> 84 85 Description 86 ----------- 87 88 This driver implements support for the National Semiconductor LM85 and 89 compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and 90 SMSC EMC6D10x chips family. 91 92 The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 93 specification. Using an analog to digital converter it measures three (3) 94 temperatures and five (5) voltages. It has four (4) 16-bit counters for 95 measuring fan speed. Five (5) digital inputs are provided for sampling the 96 VID signals from the processor to the VRM. Lastly, there are three (3) PWM 97 outputs that can be used to control fan speed. 98 99 The voltage inputs have internal scaling resistors so that the following 100 voltage can be measured without external resistors: 101 102 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V) 103 104 The temperatures measured are one internal diode, and two remote diodes. 105 Remote 1 is generally the CPU temperature. These inputs are designed to 106 measure a thermal diode like the one in a Pentium 4 processor in a socket 107 423 or socket 478 package. They can also measure temperature using a 108 transistor like the 2N3904. 109 110 A sophisticated control system for the PWM outputs is designed into the 111 LM85 that allows fan speed to be adjusted automatically based on any of the 112 three temperature sensors. Each PWM output is individually adjustable and 113 programmable. Once configured, the LM85 will adjust the PWM outputs in 114 response to the measured temperatures without further host intervention. 115 This feature can also be disabled for manual control of the PWM's. 116 117 Each of the measured inputs (voltage, temperature, fan speed) has 118 corresponding high/low limit values. The LM85 will signal an ALARM if any 119 measured value exceeds either limit. 120 121 The LM85 samples all inputs continuously. The lm85 driver will not read 122 the registers more often than once a second. Further, configuration data is 123 only read once each 5 minutes. There is twice as much config data as 124 measurements, so this would seem to be a worthwhile optimization. 125 126 Special Features 127 ---------------- 128 129 The LM85 has four fan speed monitoring modes. The ADM1027 has only two. 130 Both have special circuitry to compensate for PWM interactions with the 131 TACH signal from the fans. The ADM1027 can be configured to measure the 132 speed of a two wire fan, but the input conditioning circuitry is different 133 for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not 134 exposed to user control. The BIOS should initialize them to the correct 135 mode. If you've designed your own ADM1027, you'll have to modify the 136 init_client function and add an insmod parameter to set this up. 137 138 To smooth the response of fans to changes in temperature, the LM85 has an 139 optional filter for smoothing temperatures. The ADM1027 has the same 140 config option but uses it to rate limit the changes to fan speed instead. 141 142 The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore 143 measure temperatures with 0.25 degC resolution. They also provide an offset 144 to the temperature readings that is automatically applied during 145 measurement. This offset can be used to zero out any errors due to traces 146 and placement. The documentation says that the offset is in 0.25 degC 147 steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog 148 Devices has confirmed this "bug". The ADT7463 is reported to work as 149 described in the documentation. The current lm85 driver does not show the 150 offset register. 151 152 The ADT7468 has a high-frequency PWM mode, where all PWM outputs are 153 driven by a 22.5 kHz clock. This is a global mode, not per-PWM output, 154 which means that setting any PWM frequency above 11.3 kHz will switch 155 all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM 156 frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency 157 between 10 and 100 Hz, which can then be tuned separately. 158 159 See the vendor datasheets for more information. There is application note 160 from National (AN-1260) with some additional information about the LM85. 161 The Analog Devices datasheet is very detailed and describes a procedure for 162 determining an optimal configuration for the automatic PWM control. 163 164 The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and 165 fan speeds. They use this monitoring capability to alert the system to out 166 of limit conditions and can automatically control the speeds of multiple 167 fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP 168 package, and the EMC6D100, available in a 28-pin SSOP package, are designed 169 to be register compatible. The EMC6D100 offers all the features of the 170 EMC6D101 plus additional voltage monitoring and system control features. 171 Unfortunately it is not possible to distinguish between the package 172 versions on register level so these additional voltage inputs may read 173 zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision 174 of voltage and temperature channels. 175 176 SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl 177 and temp#_auto_temp_off. 178 179 The LM96000 supports additional high frequency PWM modes (22.5 kHz, 24 kHz, 180 25.7 kHz, 27.7 kHz and 30 kHz), which can be configured on a per-PWM basis. 181 182 Hardware Configurations 183 ----------------------- 184 185 The LM85 can be jumpered for 3 different SMBus addresses. There are 186 no other hardware configuration options for the LM85. 187 188 The lm85 driver detects both LM85B and LM85C revisions of the chip. See the 189 datasheet for a complete description of the differences. Other than 190 identifying the chip, the driver behaves no differently with regard to 191 these two chips. The LM85B is recommended for new designs. 192 193 The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output 194 that can be used to signal the chipset in case a limit is exceeded or the 195 temperature sensors fail. Individual sensor interrupts can be masked so 196 they won't trigger SMBALERT. The SMBALERT output if configured replaces one 197 of the other functions (PWM2 or IN0). This functionality is not implemented 198 in current driver. 199 200 The ADT7463 and ADT7468 also have an optional THERM output/input which can 201 be connected to the processor PROC_HOT output. If available, the autofan 202 control dynamic Tmin feature can be enabled to keep the system temperature 203 within spec (just?!) with the least possible fan noise. 204 205 Configuration Notes 206 ------------------- 207 208 Besides standard interfaces driver adds following: 209 210 * Temperatures and Zones 211 212 Each temperature sensor is associated with a Zone. There are three 213 sensors and therefore three zones (# 1, 2 and 3). Each zone has the following 214 temperature configuration points: 215 216 * temp#_auto_temp_off 217 - temperature below which fans should be off or spinning very low. 218 * temp#_auto_temp_min 219 - temperature over which fans start to spin. 220 * temp#_auto_temp_max 221 - temperature when fans spin at full speed. 222 * temp#_auto_temp_crit 223 - temperature when all fans will run full speed. 224 225 PWM Control 226 ^^^^^^^^^^^ 227 228 There are three PWM outputs. The LM85 datasheet suggests that the 229 pwm3 output control both fan3 and fan4. Each PWM can be individually 230 configured and assigned to a zone for its control value. Each PWM can be 231 configured individually according to the following options. 232 233 * pwm#_auto_pwm_min 234 - this specifies the PWM value for temp#_auto_temp_off 235 temperature. (PWM value from 0 to 255) 236 237 * pwm#_auto_pwm_minctl 238 - this flags selects for temp#_auto_temp_off temperature 239 the behaviour of fans. Write 1 to let fans spinning at 240 pwm#_auto_pwm_min or write 0 to let them off. 241 242 .. note:: 243 244 It has been reported that there is a bug in the LM85 that causes 245 the flag to be associated with the zones not the PWMs. This 246 contradicts all the published documentation. Setting pwm#_min_ctl 247 in this case actually affects all PWMs controlled by zone '#'. 248 249 PWM Controlling Zone selection 250 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 251 252 * pwm#_auto_channels 253 - controls zone that is associated with PWM 254 255 Configuration choices: 256 257 ========== ============================================= 258 Value Meaning 259 ========== ============================================= 260 1 Controlled by Zone 1 261 2 Controlled by Zone 2 262 3 Controlled by Zone 3 263 23 Controlled by higher temp of Zone 2 or 3 264 123 Controlled by highest temp of Zone 1, 2 or 3 265 0 PWM always 0% (off) 266 -1 PWM always 100% (full on) 267 -2 Manual control (write to 'pwm#' to set) 268 ========== ============================================= 269 270 The National LM85's have two vendor specific configuration 271 features. Tach. mode and Spinup Control. For more details on these, 272 see the LM85 datasheet or Application Note AN-1260. These features 273 are not currently supported by the lm85 driver. 274 275 The Analog Devices ADM1027 has several vendor specific enhancements. 276 The number of pulses-per-rev of the fans can be set, Tach monitoring 277 can be optimized for PWM operation, and an offset can be applied to 278 the temperatures to compensate for systemic errors in the 279 measurements. These features are not currently supported by the lm85 280 driver. 281 282 In addition to the ADM1027 features, the ADT7463 and ADT7468 also have 283 Tmin control and THERM asserted counts. Automatic Tmin control acts to 284 adjust the Tmin value to maintain the measured temperature sensor at a 285 specified temperature. There isn't much documentation on this feature in 286 the ADT7463 data sheet. This is not supported by current driver.
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