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1 | Kernel driver adm9240 | ||
2 | ===================== | ||
3 | |||
4 | Supported chips: | ||
5 | * Analog Devices ADM9240 | ||
6 | Prefix: 'adm9240' | ||
7 | Addresses scanned: I2C 0x2c - 0x2f | ||
8 | Datasheet: Publicly available at the Analog Devices website | ||
9 | http://www.analog.com/UploadedFiles/Data_Sheets/79857778ADM9240_0.pdf | ||
10 | |||
11 | * Dallas Semiconductor DS1780 | ||
12 | Prefix: 'ds1780' | ||
13 | Addresses scanned: I2C 0x2c - 0x2f | ||
14 | Datasheet: Publicly available at the Dallas Semiconductor (Maxim) website | ||
15 | http://pdfserv.maxim-ic.com/en/ds/DS1780.pdf | ||
16 | |||
17 | * National Semiconductor LM81 | ||
18 | Prefix: 'lm81' | ||
19 | Addresses scanned: I2C 0x2c - 0x2f | ||
20 | Datasheet: Publicly available at the National Semiconductor website | ||
21 | http://www.national.com/ds.cgi/LM/LM81.pdf | ||
22 | |||
23 | Authors: | ||
24 | Frodo Looijaard <frodol@dds.nl>, | ||
25 | Philip Edelbrock <phil@netroedge.com>, | ||
26 | Michiel Rook <michiel@grendelproject.nl>, | ||
27 | Grant Coady <gcoady@gmail.com> with guidance | ||
28 | from Jean Delvare <khali@linux-fr.org> | ||
29 | |||
30 | Interface | ||
31 | --------- | ||
32 | The I2C addresses listed above assume BIOS has not changed the | ||
33 | chip MSB 5-bit address. Each chip reports a unique manufacturer | ||
34 | identification code as well as the chip revision/stepping level. | ||
35 | |||
36 | Description | ||
37 | ----------- | ||
38 | [From ADM9240] The ADM9240 is a complete system hardware monitor for | ||
39 | microprocessor-based systems, providing measurement and limit comparison | ||
40 | of up to four power supplies and two processor core voltages, plus | ||
41 | temperature, two fan speeds and chassis intrusion. Measured values can | ||
42 | be read out via an I2C-compatible serial System Management Bus, and values | ||
43 | for limit comparisons can be programmed in over the same serial bus. The | ||
44 | high speed successive approximation ADC allows frequent sampling of all | ||
45 | analog channels to ensure a fast interrupt response to any out-of-limit | ||
46 | measurement. | ||
47 | |||
48 | The ADM9240, DS1780 and LM81 are register compatible, the following | ||
49 | details are common to the three chips. Chip differences are described | ||
50 | after this section. | ||
51 | |||
52 | |||
53 | Measurements | ||
54 | ------------ | ||
55 | The measurement cycle | ||
56 | |||
57 | The adm9240 driver will take a measurement reading no faster than once | ||
58 | each two seconds. User-space may read sysfs interface faster than the | ||
59 | measurement update rate and will receive cached data from the most | ||
60 | recent measurement. | ||
61 | |||
62 | ADM9240 has a very fast 320us temperature and voltage measurement cycle | ||
63 | with independent fan speed measurement cycles counting alternating rising | ||
64 | edges of the fan tacho inputs. | ||
65 | |||
66 | DS1780 measurement cycle is about once per second including fan speed. | ||
67 | |||
68 | LM81 measurement cycle is about once per 400ms including fan speed. | ||
69 | The LM81 12-bit extended temperature measurement mode is not supported. | ||
70 | |||
71 | Temperature | ||
72 | ----------- | ||
73 | On chip temperature is reported as degrees Celsius as 9-bit signed data | ||
74 | with resolution of 0.5 degrees Celsius. High and low temperature limits | ||
75 | are 8-bit signed data with resolution of one degree Celsius. | ||
76 | |||
77 | Temperature alarm is asserted once the temperature exceeds the high limit, | ||
78 | and is cleared when the temperature falls below the temp1_max_hyst value. | ||
79 | |||
80 | Fan Speed | ||
81 | --------- | ||
82 | Two fan tacho inputs are provided, the ADM9240 gates an internal 22.5kHz | ||
83 | clock via a divider to an 8-bit counter. Fan speed (rpm) is calculated by: | ||
84 | |||
85 | rpm = (22500 * 60) / (count * divider) | ||
86 | |||
87 | Automatic fan clock divider | ||
88 | |||
89 | * User sets 0 to fan_min limit | ||
90 | - low speed alarm is disabled | ||
91 | - fan clock divider not changed | ||
92 | - auto fan clock adjuster enabled for valid fan speed reading | ||
93 | |||
94 | * User sets fan_min limit too low | ||
95 | - low speed alarm is enabled | ||
96 | - fan clock divider set to max | ||
97 | - fan_min set to register value 254 which corresponds | ||
98 | to 664 rpm on adm9240 | ||
99 | - low speed alarm will be asserted if fan speed is | ||
100 | less than minimum measurable speed | ||
101 | - auto fan clock adjuster disabled | ||
102 | |||
103 | * User sets reasonable fan speed | ||
104 | - low speed alarm is enabled | ||
105 | - fan clock divider set to suit fan_min | ||
106 | - auto fan clock adjuster enabled: adjusts fan_min | ||
107 | |||
108 | * User sets unreasonably high low fan speed limit | ||
109 | - resolution of the low speed limit may be reduced | ||
110 | - alarm will be asserted | ||
111 | - auto fan clock adjuster enabled: adjusts fan_min | ||
112 | |||
113 | * fan speed may be displayed as zero until the auto fan clock divider | ||
114 | adjuster brings fan speed clock divider back into chip measurement | ||
115 | range, this will occur within a few measurement cycles. | ||
116 | |||
117 | Analog Output | ||
118 | ------------- | ||
119 | An analog output provides a 0 to 1.25 volt signal intended for an external | ||
120 | fan speed amplifier circuit. The analog output is set to maximum value on | ||
121 | power up or reset. This doesn't do much on the test Intel SE440BX-2. | ||
122 | |||
123 | Voltage Monitor | ||
124 | |||
125 | Voltage (IN) measurement is internally scaled: | ||
126 | |||
127 | nr label nominal maximum resolution | ||
128 | mV mV mV | ||
129 | 0 +2.5V 2500 3320 13.0 | ||
130 | 1 Vccp1 2700 3600 14.1 | ||
131 | 2 +3.3V 3300 4380 17.2 | ||
132 | 3 +5V 5000 6640 26.0 | ||
133 | 4 +12V 12000 15940 62.5 | ||
134 | 5 Vccp2 2700 3600 14.1 | ||
135 | |||
136 | The reading is an unsigned 8-bit value, nominal voltage measurement is | ||
137 | represented by a reading of 192, being 3/4 of the measurement range. | ||
138 | |||
139 | An alarm is asserted for any voltage going below or above the set limits. | ||
140 | |||
141 | The driver reports and accepts voltage limits scaled to the above table. | ||
142 | |||
143 | VID Monitor | ||
144 | ----------- | ||
145 | The chip has five inputs to read the 5-bit VID and reports the mV value | ||
146 | based on detected CPU type. | ||
147 | |||
148 | Chassis Intrusion | ||
149 | ----------------- | ||
150 | An alarm is asserted when the CI pin goes active high. The ADM9240 | ||
151 | Datasheet has an example of an external temperature sensor driving | ||
152 | this pin. On an Intel SE440BX-2 the Chassis Intrusion header is | ||
153 | connected to a normally open switch. | ||
154 | |||
155 | The ADM9240 provides an internal open drain on this line, and may output | ||
156 | a 20 ms active low pulse to reset an external Chassis Intrusion latch. | ||
157 | |||
158 | Clear the CI latch by writing value 1 to the sysfs chassis_clear file. | ||
159 | |||
160 | Alarm flags reported as 16-bit word | ||
161 | |||
162 | bit label comment | ||
163 | --- ------------- -------------------------- | ||
164 | 0 +2.5 V_Error high or low limit exceeded | ||
165 | 1 VCCP_Error high or low limit exceeded | ||
166 | 2 +3.3 V_Error high or low limit exceeded | ||
167 | 3 +5 V_Error high or low limit exceeded | ||
168 | 4 Temp_Error temperature error | ||
169 | 6 FAN1_Error fan low limit exceeded | ||
170 | 7 FAN2_Error fan low limit exceeded | ||
171 | 8 +12 V_Error high or low limit exceeded | ||
172 | 9 VCCP2_Error high or low limit exceeded | ||
173 | 12 Chassis_Error CI pin went high | ||
174 | |||
175 | Remaining bits are reserved and thus undefined. It is important to note | ||
176 | that alarm bits may be cleared on read, user-space may latch alarms and | ||
177 | provide the end-user with a method to clear alarm memory. | ||