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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 | ||
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@penguincomputing.com>, | ||
28 | Frodo Looijaard <frodol@dds.nl>, | ||
29 | Richard Barrington <rich_b_nz@clear.net.nz>, | ||
30 | Margit Schubert-While <margitsw@t-online.de>, | ||
31 | Justin Thiessen <jthiessen@penguincomputing.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. | ||