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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 | |
0ea6e611 | 12 | Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADM1027 |
7f15b664 M |
13 | * Analog Devices ADT7463 |
14 | Prefix: 'adt7463' | |
15 | Addresses scanned: I2C 0x2c, 0x2d, 0x2e | |
0ea6e611 | 16 | Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7463 |
c36364db JD |
17 | * Analog Devices ADT7468 |
18 | Prefix: 'adt7468' | |
19 | Addresses scanned: I2C 0x2c, 0x2d, 0x2e | |
20 | Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7468 | |
7f15b664 M |
21 | * SMSC EMC6D100, SMSC EMC6D101 |
22 | Prefix: 'emc6d100' | |
23 | Addresses scanned: I2C 0x2c, 0x2d, 0x2e | |
0ea6e611 | 24 | Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf |
7f15b664 M |
25 | * SMSC EMC6D102 |
26 | Prefix: 'emc6d102' | |
27 | Addresses scanned: I2C 0x2c, 0x2d, 0x2e | |
28 | Datasheet: http://www.smsc.com/main/catalog/emc6d102.html | |
06923f84 GR |
29 | * 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 | |
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37 | |
38 | Authors: | |
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 | ||
45 | Description | |
46 | ----------- | |
47 | ||
48 | This driver implements support for the National Semiconductor LM85 and | |
c36364db | 49 | compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and |
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50 | SMSC EMC6D10x chips family. |
51 | ||
52 | The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 | |
53 | specification. Using an analog to digital converter it measures three (3) | |
54 | temperatures and five (5) voltages. It has four (4) 16-bit counters for | |
55 | measuring fan speed. Five (5) digital inputs are provided for sampling the | |
56 | VID signals from the processor to the VRM. Lastly, there are three (3) PWM | |
57 | outputs that can be used to control fan speed. | |
58 | ||
59 | The voltage inputs have internal scaling resistors so that the following | |
60 | voltage can be measured without external resistors: | |
61 | ||
62 | 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V) | |
63 | ||
64 | The temperatures measured are one internal diode, and two remote diodes. | |
65 | Remote 1 is generally the CPU temperature. These inputs are designed to | |
66 | measure a thermal diode like the one in a Pentium 4 processor in a socket | |
67 | 423 or socket 478 package. They can also measure temperature using a | |
68 | transistor like the 2N3904. | |
69 | ||
70 | A sophisticated control system for the PWM outputs is designed into the | |
71 | LM85 that allows fan speed to be adjusted automatically based on any of the | |
72 | three temperature sensors. Each PWM output is individually adjustable and | |
73 | programmable. Once configured, the LM85 will adjust the PWM outputs in | |
74 | response to the measured temperatures without further host intervention. | |
75 | This feature can also be disabled for manual control of the PWM's. | |
76 | ||
77 | Each of the measured inputs (voltage, temperature, fan speed) has | |
78 | corresponding high/low limit values. The LM85 will signal an ALARM if any | |
79 | measured value exceeds either limit. | |
80 | ||
81 | The LM85 samples all inputs continuously. The lm85 driver will not read | |
82 | the registers more often than once a second. Further, configuration data is | |
83 | only read once each 5 minutes. There is twice as much config data as | |
84 | measurements, so this would seem to be a worthwhile optimization. | |
85 | ||
86 | Special Features | |
87 | ---------------- | |
88 | ||
89 | The LM85 has four fan speed monitoring modes. The ADM1027 has only two. | |
90 | Both have special circuitry to compensate for PWM interactions with the | |
91 | TACH signal from the fans. The ADM1027 can be configured to measure the | |
92 | speed of a two wire fan, but the input conditioning circuitry is different | |
93 | for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not | |
94 | exposed to user control. The BIOS should initialize them to the correct | |
95 | mode. If you've designed your own ADM1027, you'll have to modify the | |
96 | init_client function and add an insmod parameter to set this up. | |
97 | ||
98 | To smooth the response of fans to changes in temperature, the LM85 has an | |
99 | optional filter for smoothing temperatures. The ADM1027 has the same | |
100 | config option but uses it to rate limit the changes to fan speed instead. | |
101 | ||
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102 | The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore |
103 | measure temperatures with 0.25 degC resolution. They also provide an offset | |
104 | to the temperature readings that is automatically applied during | |
105 | measurement. This offset can be used to zero out any errors due to traces | |
106 | and placement. The documentation says that the offset is in 0.25 degC | |
107 | steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog | |
108 | Devices has confirmed this "bug". The ADT7463 is reported to work as | |
109 | described in the documentation. The current lm85 driver does not show the | |
110 | offset register. | |
7f15b664 | 111 | |
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112 | The ADT7468 has a high-frequency PWM mode, where all PWM outputs are |
113 | driven by a 22.5 kHz clock. This is a global mode, not per-PWM output, | |
114 | which means that setting any PWM frequency above 11.3 kHz will switch | |
115 | all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM | |
116 | frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency | |
117 | between 10 and 100 Hz, which can then be tuned separately. | |
118 | ||
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119 | See the vendor datasheets for more information. There is application note |
120 | from National (AN-1260) with some additional information about the LM85. | |
121 | The Analog Devices datasheet is very detailed and describes a procedure for | |
122 | determining an optimal configuration for the automatic PWM control. | |
123 | ||
124 | The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and | |
125 | fan speeds. They use this monitoring capability to alert the system to out | |
126 | of limit conditions and can automatically control the speeds of multiple | |
127 | fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP | |
128 | package, and the EMC6D100, available in a 28-pin SSOP package, are designed | |
129 | to be register compatible. The EMC6D100 offers all the features of the | |
130 | EMC6D101 plus additional voltage monitoring and system control features. | |
131 | Unfortunately it is not possible to distinguish between the package | |
132 | versions on register level so these additional voltage inputs may read | |
06923f84 | 133 | zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision |
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134 | of voltage and temperature channels. |
135 | ||
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136 | SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl |
137 | and temp#_auto_temp_off. | |
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138 | |
139 | Hardware Configurations | |
140 | ----------------------- | |
141 | ||
142 | The LM85 can be jumpered for 3 different SMBus addresses. There are | |
143 | no other hardware configuration options for the LM85. | |
144 | ||
145 | The lm85 driver detects both LM85B and LM85C revisions of the chip. See the | |
146 | datasheet for a complete description of the differences. Other than | |
147 | identifying the chip, the driver behaves no differently with regard to | |
148 | these two chips. The LM85B is recommended for new designs. | |
149 | ||
c36364db JD |
150 | The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output |
151 | that can be used to signal the chipset in case a limit is exceeded or the | |
152 | temperature sensors fail. Individual sensor interrupts can be masked so | |
153 | they won't trigger SMBALERT. The SMBALERT output if configured replaces one | |
154 | of the other functions (PWM2 or IN0). This functionality is not implemented | |
155 | in current driver. | |
7f15b664 | 156 | |
c36364db JD |
157 | The ADT7463 and ADT7468 also have an optional THERM output/input which can |
158 | be connected to the processor PROC_HOT output. If available, the autofan | |
159 | control dynamic Tmin feature can be enabled to keep the system temperature | |
160 | within spec (just?!) with the least possible fan noise. | |
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161 | |
162 | Configuration Notes | |
163 | ------------------- | |
164 | ||
165 | Besides standard interfaces driver adds following: | |
166 | ||
167 | * Temperatures and Zones | |
168 | ||
169 | Each temperature sensor is associated with a Zone. There are three | |
170 | sensors and therefore three zones (# 1, 2 and 3). Each zone has the following | |
171 | temperature 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 | ||
180 | There are three PWM outputs. The LM85 datasheet suggests that the | |
181 | pwm3 output control both fan3 and fan4. Each PWM can be individually | |
a33f3224 | 182 | configured and assigned to a zone for its control value. Each PWM can be |
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183 | configured 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 | ||
7f15b664 | 188 | * pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature |
77fa49d9 | 189 | the behaviour of fans. Write 1 to let fans spinning at |
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190 | pwm#_auto_pwm_min or write 0 to let them off. |
191 | ||
192 | NOTE: It has been reported that there is a bug in the LM85 that causes the flag | |
193 | to be associated with the zones not the PWMs. This contradicts all the | |
194 | published documentation. Setting pwm#_min_ctl in this case actually affects all | |
195 | PWMs controlled by zone '#'. | |
196 | ||
197 | * PWM Controlling Zone selection | |
198 | ||
199 | * pwm#_auto_channels - controls zone that is associated with PWM | |
200 | ||
201 | Configuration 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 | ||
214 | The National LM85's have two vendor specific configuration | |
215 | features. Tach. mode and Spinup Control. For more details on these, | |
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216 | see the LM85 datasheet or Application Note AN-1260. These features |
217 | are not currently supported by the lm85 driver. | |
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218 | |
219 | The Analog Devices ADM1027 has several vendor specific enhancements. | |
220 | The number of pulses-per-rev of the fans can be set, Tach monitoring | |
221 | can be optimized for PWM operation, and an offset can be applied to | |
222 | the temperatures to compensate for systemic errors in the | |
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223 | measurements. These features are not currently supported by the lm85 |
224 | driver. | |
7f15b664 | 225 | |
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226 | In addition to the ADM1027 features, the ADT7463 and ADT7468 also have |
227 | Tmin control and THERM asserted counts. Automatic Tmin control acts to | |
228 | adjust the Tmin value to maintain the measured temperature sensor at a | |
229 | specified temperature. There isn't much documentation on this feature in | |
230 | the ADT7463 data sheet. This is not supported by current driver. |