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a0ef1483 GC |
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>, | |
2ca7b961 | 27 | Grant Coady <gcoady.lk@gmail.com> with guidance |
a0ef1483 GC |
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. |