1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
Kernel driver `lm90.o'
======================
Status: Complete and well tested
Supported chips:
* National Semiconductor LM90
Prefix: 'lm90'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/pf/LM/LM90.html
* National Semiconductor LM89
Prefix: 'lm99'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/pf/LM/LM89.html
* National Semiconductor LM99
Prefix: 'lm99'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/pf/LM/LM99.html
* National Semiconductor LM86
Prefix: 'lm86'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/pf/LM/LM86.html
* Analog Devices ADM1032
Prefix: 'adm1032'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the Analog Devices website
http://www.analog.com/en/prod/0,2877,ADM1032,00.html
* Analog Devices ADT7461
Prefix: 'adt7461'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the Analog Devices website
http://www.analog.com/en/prod/0,2877,ADT7461,00.html
Note: Only if in ADM1032 compatibility mode
* Maxim MAX6657
Prefix: 'max6657'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
* Maxim MAX6658
Prefix: 'max6657'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
* Maxim MAX6659
Prefix: 'max6657'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
Author: Jean Delvare <khali@linux-fr.org>
License: GPL
Module Parameters
-----------------
* force: short array (min = 1, max = 48)
List of adapter,address pairs to boldly assume to be present
* force_lm90: short array (min = 1, max = 48)
List of adapter,address pairs which are unquestionably assumed to contain
a `lm90' chip
* force_adm1032: short array (min = 1, max = 48)
List of adapter,address pairs which are unquestionably assumed to contain
a `adm1032' chip
* force_lm99: short array (min = 1, max = 48)
List of adapter,address pairs which are unquestionably assumed to contain
a `lm99' chip
* force_lm86: short array (min = 1, max = 48)
List of adapter,address pairs which are unquestionably assumed to contain
a `lm86' chip
* force_max6657: short array (min = 1, max = 48)
List of adapter,address pairs which are unquestionably assumed to contain
a `max6657' chip
* force_adt7461: short array (min = 1, max = 48)
List of adapter,address pairs which are unquestionably assumed to contain
a `adt7461' chip
* probe: short array (min = 1, max = 48)
List of adapter,address pairs to scan additionally
* probe_range: short array (min = 1, max = 48)
List of adapter,start-addr,end-addr triples to scan additionally
* ignore: short array (min = 1, max = 48)
List of adapter,address pairs not to scan
* ignore_range: short array (min = 1, max = 48)
List of adapter,start-addr,end-addr triples not to scan
Description
-----------
The LM90 is a digital temperature sensor. It senses its own temperature as
well as the temperature of up to one external diode. It is compatible
with many other devices such as the LM86, the LM89, the LM99, the ADM1032,
the MAX6657, the MAX6658, and the MAX6659, all of which are supported by
this driver. Additionally, the ADT7461 is supported if found in ADM1032
compatibility mode.
The specificity of this family of chipsets over the ADM1021/LM84
family is that it features critical limits with hysteresis, and an
increased resolution of the remote temperature measurement.
The different chipsets of the family are not strictly identical, although
very similar. This driver doesn't handle any specific feature for now,
with the exception of SMBus PEC. For reference, here comes a non-exhaustive
list of specific features:
LM90:
* Filter and alert configuration register at 0xBF.
* ALERT is triggered by temperatures over critical limits.
LM86 and LM89:
* Same as LM90
* Better external channel accuracy
LM99:
* Same as LM89
* External temperature shifted by 16 degrees down
ADM1032:
* Consecutive alert register at 0x22.
* Conversion averaging.
* Up to 64 conversions/s.
* ALERT is triggered by open remote sensor.
* SMBus PEC support for Write Byte and Receive Byte transactions.
ADT7461
* Extended temperature range (breaks compatibility)
* Lower resolution for remote temperature
MAX6657 and MAX6658:
* Remote sensor type selecion
MAX6659
* Selectable address
* Second critical temperature limit
All temperature values are given in degrees Celsius. Resolution
is 1.0 degree for the local temperature, 0.125 degree for the remote
temperature.
Each sensor has its own high and low limits, plus a critical limit.
Additionally, there is a relative hysteresis value common to both critical
values. To make life easier to user-space applications, two absolute values
are exported, one for each channel, but these values are of course linked.
Only the local hysteresis can be set from user-space, and the same delta
applies to the remote hysteresis.
The lm90 driver will not update its values more frequently than every
other second; reading them more often will do no harm, but will return
'old' values.
PEC Support
-----------
The ADM1032 is the only chip of the family which supports PEC. It does
not support PEC on all transactions though, so some care must be taken.
When reading a register value, the PEC byte is computed and sent by the
ADM1032 chip. However, in the case of a combined transaction (SMBus Read
Byte), the ADM1032 computes the CRC value over only the second half of
the message rather than its entirety, because it thinks the first half
of the message belongs to a different transaction. As a result, the CRC
value differs from what the SMBus master expects, and all reads fail.
For this reason, the lm90 driver will enable PEC for the ADM1032 only if
the bus supports the SMBus Send Byte and Receive Byte transaction types.
These transactions will be used to read register values, instead of
SMBus Read Byte, and PEC will work properly.
Additionally, the ADM1032 doesn't support SMBus Send Byte with PEC.
Instead, it will try to write the PEC value to the register (because the
SMBus Send Byte transaction with PEC is similar to a Write Byte transaction
without PEC), which is not what we want. Thus, PEC is explicitly disabled
on SMBus Send Byte transactions in the lm90 driver.
PEC on byte data transactions represents a significant increase in bandwidth
usage (+33% for writes, +25% for reads) in normal conditions. With the need
to use two SMBus transaction for reads, this overhead jumps to +50%. Worse,
two transactions will typically mean twice as much delay waiting for
transaction completion, effectively doubling the register cache refresh time.
I guess reliability comes at a price, but it's quite expensive this time.
So, as not everyone might enjoy the slowdown, PEC can be disabled through
procfs. Just write 0 to the "pec" file and PEC will be disabled. Write 1
to that file to enable PEC again.
Chip Features
-------------
Chips 'lm90', adm1032', 'lm99', 'lm86', 'max6657' and 'adt7461'
LABEL LABEL CLASS COMPUTE CLASS MODE MAGN
temp1 - - R- 0
temp1_high temp1 temp1 RW 0
temp1_low temp1 temp1 RW 0
temp2 - - R- 1
temp2_high temp2 temp2 RW 1
temp2_low temp2 temp2 RW 1
tcrit1 temp1 temp1 RW 0
tcrit2 temp2 temp2 RW 0
hyst1 temp1 temp1 RW 0
hyst2 temp2 temp2 R- 0
alarms - - R- 0
LABEL FEATURE SYMBOL SYSCTL FILE:N
temp1 SENSORS_LM90_LOCAL_TEMP temp1:3
temp1_high SENSORS_LM90_LOCAL_HIGH temp1:1
temp1_low SENSORS_LM90_LOCAL_LOW temp1:2
temp2 SENSORS_LM90_REMOTE_TEMP temp2:3
temp2_high SENSORS_LM90_REMOTE_HIGH temp2:1
temp2_low SENSORS_LM90_REMOTE_LOW temp2:2
tcrit1 SENSORS_LM90_LOCAL_TCRIT tcrit1:1
tcrit2 SENSORS_LM90_REMOTE_TCRIT tcrit2:1
hyst1 SENSORS_LM90_LOCAL_TCRIT_HYST hyst1:1
hyst2 SENSORS_LM90_REMOTE_TCRIT_HYST hyst2:1
alarms SENSORS_LM90_ALARMS alarms:1
|
