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R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +00001Kernel driver lm85
2==================
3
4Supported 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
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070012 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADM1027
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000013 * Analog Devices ADT7463
14 Prefix: 'adt7463'
15 Addresses scanned: I2C 0x2c, 0x2d, 0x2e
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070016 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7463
Jean Delvarec36364d2010-10-28 20:31:50 +020017 * Analog Devices ADT7468
18 Prefix: 'adt7468'
19 Addresses scanned: I2C 0x2c, 0x2d, 0x2e
20 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7468
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000021 * SMSC EMC6D100, SMSC EMC6D101
22 Prefix: 'emc6d100'
23 Addresses scanned: I2C 0x2c, 0x2d, 0x2e
Justin P. Mattock0ea6e612010-07-23 20:51:24 -070024 Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000025 * SMSC EMC6D102
26 Prefix: 'emc6d102'
27 Addresses scanned: I2C 0x2c, 0x2d, 0x2e
28 Datasheet: http://www.smsc.com/main/catalog/emc6d102.html
Guenter Roeck06923f82011-02-19 08:27:47 -080029 * 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
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000037
38Authors:
39 Philip Pokorny <ppokorny@penguincomputing.com>,
40 Frodo Looijaard <frodol@dds.nl>,
41 Richard Barrington <rich_b_nz@clear.net.nz>,
42 Margit Schubert-While <margitsw@t-online.de>,
43 Justin Thiessen <jthiessen@penguincomputing.com>
44
45Description
46-----------
47
48This driver implements support for the National Semiconductor LM85 and
Jean Delvarec36364d2010-10-28 20:31:50 +020049compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000050SMSC EMC6D10x chips family.
51
52The LM85 uses the 2-wire interface compatible with the SMBUS 2.0
53specification. Using an analog to digital converter it measures three (3)
54temperatures and five (5) voltages. It has four (4) 16-bit counters for
55measuring fan speed. Five (5) digital inputs are provided for sampling the
56VID signals from the processor to the VRM. Lastly, there are three (3) PWM
57outputs that can be used to control fan speed.
58
59The voltage inputs have internal scaling resistors so that the following
60voltage can be measured without external resistors:
61
62 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V)
63
64The temperatures measured are one internal diode, and two remote diodes.
65Remote 1 is generally the CPU temperature. These inputs are designed to
66measure a thermal diode like the one in a Pentium 4 processor in a socket
67423 or socket 478 package. They can also measure temperature using a
68transistor like the 2N3904.
69
70A sophisticated control system for the PWM outputs is designed into the
71LM85 that allows fan speed to be adjusted automatically based on any of the
72three temperature sensors. Each PWM output is individually adjustable and
73programmable. Once configured, the LM85 will adjust the PWM outputs in
74response to the measured temperatures without further host intervention.
75This feature can also be disabled for manual control of the PWM's.
76
77Each of the measured inputs (voltage, temperature, fan speed) has
78corresponding high/low limit values. The LM85 will signal an ALARM if any
79measured value exceeds either limit.
80
81The LM85 samples all inputs continuously. The lm85 driver will not read
82the registers more often than once a second. Further, configuration data is
83only read once each 5 minutes. There is twice as much config data as
84measurements, so this would seem to be a worthwhile optimization.
85
86Special Features
87----------------
88
89The LM85 has four fan speed monitoring modes. The ADM1027 has only two.
90Both have special circuitry to compensate for PWM interactions with the
91TACH signal from the fans. The ADM1027 can be configured to measure the
92speed of a two wire fan, but the input conditioning circuitry is different
93for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not
94exposed to user control. The BIOS should initialize them to the correct
95mode. If you've designed your own ADM1027, you'll have to modify the
96init_client function and add an insmod parameter to set this up.
97
98To smooth the response of fans to changes in temperature, the LM85 has an
99optional filter for smoothing temperatures. The ADM1027 has the same
100config option but uses it to rate limit the changes to fan speed instead.
101
Jean Delvarec36364d2010-10-28 20:31:50 +0200102The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore
103measure temperatures with 0.25 degC resolution. They also provide an offset
104to the temperature readings that is automatically applied during
105measurement. This offset can be used to zero out any errors due to traces
106and placement. The documentation says that the offset is in 0.25 degC
107steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog
108Devices has confirmed this "bug". The ADT7463 is reported to work as
109described in the documentation. The current lm85 driver does not show the
110offset register.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000111
Jean Delvaref6c61cf2010-10-28 20:31:50 +0200112The ADT7468 has a high-frequency PWM mode, where all PWM outputs are
113driven by a 22.5 kHz clock. This is a global mode, not per-PWM output,
114which means that setting any PWM frequency above 11.3 kHz will switch
115all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM
116frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency
117between 10 and 100 Hz, which can then be tuned separately.
118
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000119See the vendor datasheets for more information. There is application note
120from National (AN-1260) with some additional information about the LM85.
121The Analog Devices datasheet is very detailed and describes a procedure for
122determining an optimal configuration for the automatic PWM control.
123
124The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and
125fan speeds. They use this monitoring capability to alert the system to out
126of limit conditions and can automatically control the speeds of multiple
127fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP
128package, and the EMC6D100, available in a 28-pin SSOP package, are designed
129to be register compatible. The EMC6D100 offers all the features of the
130EMC6D101 plus additional voltage monitoring and system control features.
131Unfortunately it is not possible to distinguish between the package
132versions on register level so these additional voltage inputs may read
Guenter Roeck06923f82011-02-19 08:27:47 -0800133zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000134of voltage and temperature channels.
135
Guenter Roeck06923f82011-02-19 08:27:47 -0800136SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl
137and temp#_auto_temp_off.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000138
139Hardware Configurations
140-----------------------
141
142The LM85 can be jumpered for 3 different SMBus addresses. There are
143no other hardware configuration options for the LM85.
144
145The lm85 driver detects both LM85B and LM85C revisions of the chip. See the
146datasheet for a complete description of the differences. Other than
147identifying the chip, the driver behaves no differently with regard to
148these two chips. The LM85B is recommended for new designs.
149
Jean Delvarec36364d2010-10-28 20:31:50 +0200150The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output
151that can be used to signal the chipset in case a limit is exceeded or the
152temperature sensors fail. Individual sensor interrupts can be masked so
153they won't trigger SMBALERT. The SMBALERT output if configured replaces one
154of the other functions (PWM2 or IN0). This functionality is not implemented
155in current driver.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000156
Jean Delvarec36364d2010-10-28 20:31:50 +0200157The ADT7463 and ADT7468 also have an optional THERM output/input which can
158be connected to the processor PROC_HOT output. If available, the autofan
159control dynamic Tmin feature can be enabled to keep the system temperature
160within spec (just?!) with the least possible fan noise.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000161
162Configuration Notes
163-------------------
164
165Besides standard interfaces driver adds following:
166
167* Temperatures and Zones
168
169Each temperature sensor is associated with a Zone. There are three
170sensors and therefore three zones (# 1, 2 and 3). Each zone has the following
171temperature 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
180There are three PWM outputs. The LM85 datasheet suggests that the
181pwm3 output control both fan3 and fan4. Each PWM can be individually
Francis Galieguea33f3222010-04-23 00:08:02 +0200182configured and assigned to a zone for its control value. Each PWM can be
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000183configured 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
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000188* pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature
Jean Delvare77fa49d2009-01-07 16:37:35 +0100189 the behaviour of fans. Write 1 to let fans spinning at
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000190 pwm#_auto_pwm_min or write 0 to let them off.
191
192NOTE: It has been reported that there is a bug in the LM85 that causes the flag
193to be associated with the zones not the PWMs. This contradicts all the
194published documentation. Setting pwm#_min_ctl in this case actually affects all
195PWMs controlled by zone '#'.
196
197* PWM Controlling Zone selection
198
199* pwm#_auto_channels - controls zone that is associated with PWM
200
201Configuration 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
214The National LM85's have two vendor specific configuration
215features. Tach. mode and Spinup Control. For more details on these,
Jean Delvaredd1ac532008-05-01 08:47:33 +0200216see the LM85 datasheet or Application Note AN-1260. These features
217are not currently supported by the lm85 driver.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000218
219The Analog Devices ADM1027 has several vendor specific enhancements.
220The number of pulses-per-rev of the fans can be set, Tach monitoring
221can be optimized for PWM operation, and an offset can be applied to
222the temperatures to compensate for systemic errors in the
Jean Delvaredd1ac532008-05-01 08:47:33 +0200223measurements. These features are not currently supported by the lm85
224driver.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000225
Jean Delvarec36364d2010-10-28 20:31:50 +0200226In addition to the ADM1027 features, the ADT7463 and ADT7468 also have
227Tmin control and THERM asserted counts. Automatic Tmin control acts to
228adjust the Tmin value to maintain the measured temperature sensor at a
229specified temperature. There isn't much documentation on this feature in
230the ADT7463 data sheet. This is not supported by current driver.