| Kernel driver lm85 |
| ================== |
| |
| Supported chips: |
| |
| * National Semiconductor LM85 (B and C versions) |
| |
| Prefix: 'lm85b' or 'lm85c' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: http://www.national.com/pf/LM/LM85.html |
| |
| * Texas Instruments LM96000 |
| |
| Prefix: 'lm9600' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: https://www.ti.com/lit/ds/symlink/lm96000.pdf |
| |
| * Analog Devices ADM1027 |
| |
| Prefix: 'adm1027' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: https://www.onsemi.com/PowerSolutions/product.do?id=ADM1027 |
| |
| * Analog Devices ADT7463 |
| |
| Prefix: 'adt7463' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: https://www.onsemi.com/PowerSolutions/product.do?id=ADT7463 |
| |
| * Analog Devices ADT7468 |
| |
| Prefix: 'adt7468' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: https://www.onsemi.com/PowerSolutions/product.do?id=ADT7468 |
| |
| * SMSC EMC6D100, SMSC EMC6D101 |
| |
| Prefix: 'emc6d100' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf |
| |
| * SMSC EMC6D102 |
| |
| Prefix: 'emc6d102' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: http://www.smsc.com/main/catalog/emc6d102.html |
| |
| * SMSC EMC6D103 |
| |
| Prefix: 'emc6d103' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: http://www.smsc.com/main/catalog/emc6d103.html |
| |
| * SMSC EMC6D103S |
| |
| Prefix: 'emc6d103s' |
| |
| Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
| |
| Datasheet: http://www.smsc.com/main/catalog/emc6d103s.html |
| |
| Authors: |
| - Philip Pokorny <ppokorny@penguincomputing.com>, |
| - Frodo Looijaard <frodol@dds.nl>, |
| - Richard Barrington <rich_b_nz@clear.net.nz>, |
| - Margit Schubert-While <margitsw@t-online.de>, |
| - Justin Thiessen <jthiessen@penguincomputing.com> |
| |
| Description |
| ----------- |
| |
| This driver implements support for the National Semiconductor LM85 and |
| compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and |
| SMSC EMC6D10x chips family. |
| |
| The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 |
| specification. Using an analog to digital converter it measures three (3) |
| temperatures and five (5) voltages. It has four (4) 16-bit counters for |
| measuring fan speed. Five (5) digital inputs are provided for sampling the |
| VID signals from the processor to the VRM. Lastly, there are three (3) PWM |
| outputs that can be used to control fan speed. |
| |
| The voltage inputs have internal scaling resistors so that the following |
| voltage can be measured without external resistors: |
| |
| 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V) |
| |
| The temperatures measured are one internal diode, and two remote diodes. |
| Remote 1 is generally the CPU temperature. These inputs are designed to |
| measure a thermal diode like the one in a Pentium 4 processor in a socket |
| 423 or socket 478 package. They can also measure temperature using a |
| transistor like the 2N3904. |
| |
| A sophisticated control system for the PWM outputs is designed into the |
| LM85 that allows fan speed to be adjusted automatically based on any of the |
| three temperature sensors. Each PWM output is individually adjustable and |
| programmable. Once configured, the LM85 will adjust the PWM outputs in |
| response to the measured temperatures without further host intervention. |
| This feature can also be disabled for manual control of the PWM's. |
| |
| Each of the measured inputs (voltage, temperature, fan speed) has |
| corresponding high/low limit values. The LM85 will signal an ALARM if any |
| measured value exceeds either limit. |
| |
| The LM85 samples all inputs continuously. The lm85 driver will not read |
| the registers more often than once a second. Further, configuration data is |
| only read once each 5 minutes. There is twice as much config data as |
| measurements, so this would seem to be a worthwhile optimization. |
| |
| Special Features |
| ---------------- |
| |
| The LM85 has four fan speed monitoring modes. The ADM1027 has only two. |
| Both have special circuitry to compensate for PWM interactions with the |
| TACH signal from the fans. The ADM1027 can be configured to measure the |
| speed of a two wire fan, but the input conditioning circuitry is different |
| for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not |
| exposed to user control. The BIOS should initialize them to the correct |
| mode. If you've designed your own ADM1027, you'll have to modify the |
| init_client function and add an insmod parameter to set this up. |
| |
| To smooth the response of fans to changes in temperature, the LM85 has an |
| optional filter for smoothing temperatures. The ADM1027 has the same |
| config option but uses it to rate limit the changes to fan speed instead. |
| |
| The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore |
| measure temperatures with 0.25 degC resolution. They also provide an offset |
| to the temperature readings that is automatically applied during |
| measurement. This offset can be used to zero out any errors due to traces |
| and placement. The documentation says that the offset is in 0.25 degC |
| steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog |
| Devices has confirmed this "bug". The ADT7463 is reported to work as |
| described in the documentation. The current lm85 driver does not show the |
| offset register. |
| |
| The ADT7468 has a high-frequency PWM mode, where all PWM outputs are |
| driven by a 22.5 kHz clock. This is a global mode, not per-PWM output, |
| which means that setting any PWM frequency above 11.3 kHz will switch |
| all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM |
| frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency |
| between 10 and 100 Hz, which can then be tuned separately. |
| |
| See the vendor datasheets for more information. There is application note |
| from National (AN-1260) with some additional information about the LM85. |
| The Analog Devices datasheet is very detailed and describes a procedure for |
| determining an optimal configuration for the automatic PWM control. |
| |
| The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and |
| fan speeds. They use this monitoring capability to alert the system to out |
| of limit conditions and can automatically control the speeds of multiple |
| fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP |
| package, and the EMC6D100, available in a 28-pin SSOP package, are designed |
| to be register compatible. The EMC6D100 offers all the features of the |
| EMC6D101 plus additional voltage monitoring and system control features. |
| Unfortunately it is not possible to distinguish between the package |
| versions on register level so these additional voltage inputs may read |
| zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision |
| of voltage and temperature channels. |
| |
| SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl |
| and temp#_auto_temp_off. |
| |
| The LM96000 supports additional high frequency PWM modes (22.5 kHz, 24 kHz, |
| 25.7 kHz, 27.7 kHz and 30 kHz), which can be configured on a per-PWM basis. |
| |
| Hardware Configurations |
| ----------------------- |
| |
| The LM85 can be jumpered for 3 different SMBus addresses. There are |
| no other hardware configuration options for the LM85. |
| |
| The lm85 driver detects both LM85B and LM85C revisions of the chip. See the |
| datasheet for a complete description of the differences. Other than |
| identifying the chip, the driver behaves no differently with regard to |
| these two chips. The LM85B is recommended for new designs. |
| |
| The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output |
| that can be used to signal the chipset in case a limit is exceeded or the |
| temperature sensors fail. Individual sensor interrupts can be masked so |
| they won't trigger SMBALERT. The SMBALERT output if configured replaces one |
| of the other functions (PWM2 or IN0). This functionality is not implemented |
| in current driver. |
| |
| The ADT7463 and ADT7468 also have an optional THERM output/input which can |
| be connected to the processor PROC_HOT output. If available, the autofan |
| control dynamic Tmin feature can be enabled to keep the system temperature |
| within spec (just?!) with the least possible fan noise. |
| |
| Configuration Notes |
| ------------------- |
| |
| Besides standard interfaces driver adds following: |
| |
| * Temperatures and Zones |
| |
| Each temperature sensor is associated with a Zone. There are three |
| sensors and therefore three zones (# 1, 2 and 3). Each zone has the following |
| temperature configuration points: |
| |
| * temp#_auto_temp_off |
| - temperature below which fans should be off or spinning very low. |
| * temp#_auto_temp_min |
| - temperature over which fans start to spin. |
| * temp#_auto_temp_max |
| - temperature when fans spin at full speed. |
| * temp#_auto_temp_crit |
| - temperature when all fans will run full speed. |
| |
| PWM Control |
| ^^^^^^^^^^^ |
| |
| There are three PWM outputs. The LM85 datasheet suggests that the |
| pwm3 output control both fan3 and fan4. Each PWM can be individually |
| configured and assigned to a zone for its control value. Each PWM can be |
| configured individually according to the following options. |
| |
| * pwm#_auto_pwm_min |
| - this specifies the PWM value for temp#_auto_temp_off |
| temperature. (PWM value from 0 to 255) |
| |
| * pwm#_auto_pwm_minctl |
| - this flags selects for temp#_auto_temp_off temperature |
| the behaviour of fans. Write 1 to let fans spinning at |
| pwm#_auto_pwm_min or write 0 to let them off. |
| |
| .. note:: |
| |
| It has been reported that there is a bug in the LM85 that causes |
| the flag to be associated with the zones not the PWMs. This |
| contradicts all the published documentation. Setting pwm#_min_ctl |
| in this case actually affects all PWMs controlled by zone '#'. |
| |
| PWM Controlling Zone selection |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| * pwm#_auto_channels |
| - controls zone that is associated with PWM |
| |
| Configuration choices: |
| |
| ========== ============================================= |
| Value Meaning |
| ========== ============================================= |
| 1 Controlled by Zone 1 |
| 2 Controlled by Zone 2 |
| 3 Controlled by Zone 3 |
| 23 Controlled by higher temp of Zone 2 or 3 |
| 123 Controlled by highest temp of Zone 1, 2 or 3 |
| 0 PWM always 0% (off) |
| -1 PWM always 100% (full on) |
| -2 Manual control (write to 'pwm#' to set) |
| ========== ============================================= |
| |
| The National LM85's have two vendor specific configuration |
| features. Tach. mode and Spinup Control. For more details on these, |
| see the LM85 datasheet or Application Note AN-1260. These features |
| are not currently supported by the lm85 driver. |
| |
| The Analog Devices ADM1027 has several vendor specific enhancements. |
| The number of pulses-per-rev of the fans can be set, Tach monitoring |
| can be optimized for PWM operation, and an offset can be applied to |
| the temperatures to compensate for systemic errors in the |
| measurements. These features are not currently supported by the lm85 |
| driver. |
| |
| In addition to the ADM1027 features, the ADT7463 and ADT7468 also have |
| Tmin control and THERM asserted counts. Automatic Tmin control acts to |
| adjust the Tmin value to maintain the measured temperature sensor at a |
| specified temperature. There isn't much documentation on this feature in |
| the ADT7463 data sheet. This is not supported by current driver. |
