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R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +00001Kernel driver lm90
2==================
3
4Supported chips:
5 * National Semiconductor LM90
6 Prefix: 'lm90'
7 Addresses scanned: I2C 0x4c
8 Datasheet: Publicly available at the National Semiconductor website
9 http://www.national.com/pf/LM/LM90.html
10 * National Semiconductor LM89
Jean Delvare97ae60b2008-10-26 17:04:39 +010011 Prefix: 'lm89' (no auto-detection)
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000012 Addresses scanned: I2C 0x4c and 0x4d
13 Datasheet: Publicly available at the National Semiconductor website
Jean Delvarea874a102008-10-17 17:51:10 +020014 http://www.national.com/mpf/LM/LM89.html
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000015 * National Semiconductor LM99
16 Prefix: 'lm99'
17 Addresses scanned: I2C 0x4c and 0x4d
18 Datasheet: Publicly available at the National Semiconductor website
19 http://www.national.com/pf/LM/LM99.html
20 * National Semiconductor LM86
21 Prefix: 'lm86'
22 Addresses scanned: I2C 0x4c
23 Datasheet: Publicly available at the National Semiconductor website
Jean Delvarea874a102008-10-17 17:51:10 +020024 http://www.national.com/mpf/LM/LM86.html
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000025 * Analog Devices ADM1032
26 Prefix: 'adm1032'
Jean Delvare90209b42005-10-26 22:20:21 +020027 Addresses scanned: I2C 0x4c and 0x4d
Jean Delvarea874a102008-10-17 17:51:10 +020028 Datasheet: Publicly available at the ON Semiconductor website
29 http://www.onsemi.com/PowerSolutions/product.do?id=ADM1032
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000030 * Analog Devices ADT7461
31 Prefix: 'adt7461'
Jean Delvare90209b42005-10-26 22:20:21 +020032 Addresses scanned: I2C 0x4c and 0x4d
Jean Delvarea874a102008-10-17 17:51:10 +020033 Datasheet: Publicly available at the ON Semiconductor website
34 http://www.onsemi.com/PowerSolutions/product.do?id=ADT7461
Guenter Roeck5a4e5e62011-04-29 16:33:35 +020035 * Analog Devices ADT7461A
36 Prefix: 'adt7461a'
37 Addresses scanned: I2C 0x4c and 0x4d
38 Datasheet: Publicly available at the ON Semiconductor website
39 http://www.onsemi.com/PowerSolutions/product.do?id=ADT7461A
40 * ON Semiconductor NCT1008
41 Prefix: 'nct1008'
42 Addresses scanned: I2C 0x4c and 0x4d
43 Datasheet: Publicly available at the ON Semiconductor website
44 http://www.onsemi.com/PowerSolutions/product.do?id=NCT1008
Ben Hutchings271dabf2008-10-17 17:51:11 +020045 * Maxim MAX6646
46 Prefix: 'max6646'
47 Addresses scanned: I2C 0x4d
48 Datasheet: Publicly available at the Maxim website
49 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
50 * Maxim MAX6647
51 Prefix: 'max6646'
52 Addresses scanned: I2C 0x4e
53 Datasheet: Publicly available at the Maxim website
54 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
Darrick J. Wong1a51e062009-03-12 13:36:38 +010055 * Maxim MAX6648
56 Prefix: 'max6646'
57 Addresses scanned: I2C 0x4c
58 Datasheet: Publicly available at the Maxim website
59 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500
Ben Hutchings271dabf2008-10-17 17:51:11 +020060 * Maxim MAX6649
61 Prefix: 'max6646'
62 Addresses scanned: I2C 0x4c
63 Datasheet: Publicly available at the Maxim website
64 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000065 * Maxim MAX6657
66 Prefix: 'max6657'
67 Addresses scanned: I2C 0x4c
68 Datasheet: Publicly available at the Maxim website
69 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
70 * Maxim MAX6658
71 Prefix: 'max6657'
72 Addresses scanned: I2C 0x4c
73 Datasheet: Publicly available at the Maxim website
74 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
75 * Maxim MAX6659
Guenter Roeck13c84952010-10-28 20:31:43 +020076 Prefix: 'max6659'
77 Addresses scanned: I2C 0x4c, 0x4d, 0x4e
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +000078 Datasheet: Publicly available at the Maxim website
79 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
Rainer Birkenmaier32c82a92007-06-09 10:11:16 -040080 * Maxim MAX6680
81 Prefix: 'max6680'
82 Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
83 0x4c, 0x4d and 0x4e
84 Datasheet: Publicly available at the Maxim website
85 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
86 * Maxim MAX6681
87 Prefix: 'max6680'
88 Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
89 0x4c, 0x4d and 0x4e
90 Datasheet: Publicly available at the Maxim website
91 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
Darrick J. Wong1a51e062009-03-12 13:36:38 +010092 * Maxim MAX6692
93 Prefix: 'max6646'
94 Addresses scanned: I2C 0x4c
95 Datasheet: Publicly available at the Maxim website
96 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500
Guenter Roeck06e1c0a2010-10-28 20:31:43 +020097 * Maxim MAX6695
98 Prefix: 'max6695'
99 Addresses scanned: I2C 0x18
100 Datasheet: Publicly available at the Maxim website
101 http://www.maxim-ic.com/datasheet/index.mvp/id/4199
102 * Maxim MAX6696
103 Prefix: 'max6695'
104 Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
105 0x4c, 0x4d and 0x4e
106 Datasheet: Publicly available at the Maxim website
107 http://www.maxim-ic.com/datasheet/index.mvp/id/4199
Jean Delvarec4f99a22010-10-28 20:31:44 +0200108 * Winbond/Nuvoton W83L771W/G
109 Prefix: 'w83l771'
110 Addresses scanned: I2C 0x4c
111 Datasheet: No longer available
Jean Delvare6771ea12010-03-05 22:17:13 +0100112 * Winbond/Nuvoton W83L771AWG/ASG
113 Prefix: 'w83l771'
114 Addresses scanned: I2C 0x4c
115 Datasheet: Not publicly available, can be requested from Nuvoton
Stijn Devriendt2ef01792011-06-06 10:40:45 +0000116 * Philips/NXP SA56004X
117 Prefix: 'sa56004'
118 Addresses scanned: I2C 0x48 through 0x4F
119 Datasheet: Publicly available at NXP website
120 http://ics.nxp.com/products/interface/datasheet/sa56004x.pdf
Guenter Roeckae544f62012-03-23 10:02:18 +0100121 * GMT G781
122 Prefix: 'g781'
123 Addresses scanned: I2C 0x4c, 0x4d
124 Datasheet: Not publicly available from GMT
Wei Ni1daaceb2013-11-15 10:40:39 +0100125 * Texas Instruments TMP451
126 Prefix: 'tmp451'
127 Addresses scanned: I2C 0x4c
128 Datasheet: Publicly available at TI website
129 http://www.ti.com/litv/pdf/sbos686
130
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000131
Jean Delvare7c81c602014-01-29 20:40:08 +0100132Author: Jean Delvare <jdelvare@suse.de>
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000133
134
135Description
136-----------
137
138The LM90 is a digital temperature sensor. It senses its own temperature as
139well as the temperature of up to one external diode. It is compatible
Nate Case23b2d472008-10-17 17:51:10 +0200140with many other devices, many of which are supported by this driver.
Rainer Birkenmaier32c82a92007-06-09 10:11:16 -0400141
142Note that there is no easy way to differentiate between the MAX6657,
Guenter Roeck69487082010-10-28 20:31:43 +0200143MAX6658 and MAX6659 variants. The extra features of the MAX6659 are only
144supported by this driver if the chip is located at address 0x4d or 0x4e,
145or if the chip type is explicitly selected as max6659.
146The MAX6680 and MAX6681 only differ in their pinout, therefore they obviously
147can't (and don't need to) be distinguished.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000148
149The specificity of this family of chipsets over the ADM1021/LM84
150family is that it features critical limits with hysteresis, and an
151increased resolution of the remote temperature measurement.
152
153The different chipsets of the family are not strictly identical, although
Jean Delvaref65e1702008-10-17 17:51:09 +0200154very similar. For reference, here comes a non-exhaustive list of specific
155features:
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000156
157LM90:
158 * Filter and alert configuration register at 0xBF.
159 * ALERT is triggered by temperatures over critical limits.
160
161LM86 and LM89:
162 * Same as LM90
163 * Better external channel accuracy
164
165LM99:
166 * Same as LM89
167 * External temperature shifted by 16 degrees down
168
169ADM1032:
170 * Consecutive alert register at 0x22.
171 * Conversion averaging.
172 * Up to 64 conversions/s.
173 * ALERT is triggered by open remote sensor.
Jean Delvarec3df5802005-10-26 21:39:40 +0200174 * SMBus PEC support for Write Byte and Receive Byte transactions.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000175
Guenter Roeck5a4e5e62011-04-29 16:33:35 +0200176ADT7461, ADT7461A, NCT1008:
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000177 * Extended temperature range (breaks compatibility)
178 * Lower resolution for remote temperature
179
180MAX6657 and MAX6658:
Jean Delvaref65e1702008-10-17 17:51:09 +0200181 * Better local resolution
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000182 * Remote sensor type selection
183
Rainer Birkenmaier32c82a92007-06-09 10:11:16 -0400184MAX6659:
Jean Delvaref65e1702008-10-17 17:51:09 +0200185 * Better local resolution
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000186 * Selectable address
187 * Second critical temperature limit
188 * Remote sensor type selection
189
Rainer Birkenmaier32c82a92007-06-09 10:11:16 -0400190MAX6680 and MAX6681:
191 * Selectable address
192 * Remote sensor type selection
193
Guenter Roeck06e1c0a2010-10-28 20:31:43 +0200194MAX6695 and MAX6696:
195 * Better local resolution
196 * Selectable address (max6696)
197 * Second critical temperature limit
198 * Two remote sensors
199
Jean Delvarec4f99a22010-10-28 20:31:44 +0200200W83L771W/G
201 * The G variant is lead-free, otherwise similar to the W.
Jean Delvare6771ea12010-03-05 22:17:13 +0100202 * Filter and alert configuration register at 0xBF
Jean Delvare6771ea12010-03-05 22:17:13 +0100203 * Moving average (depending on conversion rate)
204
Jean Delvarec4f99a22010-10-28 20:31:44 +0200205W83L771AWG/ASG
206 * Successor of the W83L771W/G, same features.
207 * The AWG and ASG variants only differ in package format.
208 * Diode ideality factor configuration (remote sensor) at 0xE3
209
Stijn Devriendt2ef01792011-06-06 10:40:45 +0000210SA56004X:
211 * Better local resolution
212
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000213All temperature values are given in degrees Celsius. Resolution
214is 1.0 degree for the local temperature, 0.125 degree for the remote
Jean Delvaref65e1702008-10-17 17:51:09 +0200215temperature, except for the MAX6657, MAX6658 and MAX6659 which have a
216resolution of 0.125 degree for both temperatures.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000217
218Each sensor has its own high and low limits, plus a critical limit.
219Additionally, there is a relative hysteresis value common to both critical
220values. To make life easier to user-space applications, two absolute values
221are exported, one for each channel, but these values are of course linked.
222Only the local hysteresis can be set from user-space, and the same delta
223applies to the remote hysteresis.
224
Guenter Roeck177e7592011-04-29 16:33:35 +0200225The lm90 driver will not update its values more frequently than configured with
226the update_interval attribute; reading them more often will do no harm, but will
227return 'old' values.
R.Marek@sh.cvut.cz7f15b662005-05-26 12:42:19 +0000228
Jean Delvare53de3342010-03-05 22:17:15 +0100229SMBus Alert Support
230-------------------
231
232This driver has basic support for SMBus alert. When an alert is received,
233the status register is read and the faulty temperature channel is logged.
234
Guenter Roeck5a4e5e62011-04-29 16:33:35 +0200235The Analog Devices chips (ADM1032, ADT7461 and ADT7461A) and ON
236Semiconductor chips (NCT1008) do not implement the SMBus alert protocol
237properly so additional care is needed: the ALERT output is disabled when
238an alert is received, and is re-enabled only when the alarm is gone.
239Otherwise the chip would block alerts from other chips in the bus as long
240as the alarm is active.
Jean Delvare53de3342010-03-05 22:17:15 +0100241
Jean Delvarec3df5802005-10-26 21:39:40 +0200242PEC Support
243-----------
244
245The ADM1032 is the only chip of the family which supports PEC. It does
246not support PEC on all transactions though, so some care must be taken.
247
248When reading a register value, the PEC byte is computed and sent by the
249ADM1032 chip. However, in the case of a combined transaction (SMBus Read
250Byte), the ADM1032 computes the CRC value over only the second half of
251the message rather than its entirety, because it thinks the first half
252of the message belongs to a different transaction. As a result, the CRC
253value differs from what the SMBus master expects, and all reads fail.
254
255For this reason, the lm90 driver will enable PEC for the ADM1032 only if
256the bus supports the SMBus Send Byte and Receive Byte transaction types.
257These transactions will be used to read register values, instead of
258SMBus Read Byte, and PEC will work properly.
259
260Additionally, the ADM1032 doesn't support SMBus Send Byte with PEC.
261Instead, it will try to write the PEC value to the register (because the
262SMBus Send Byte transaction with PEC is similar to a Write Byte transaction
Jean Delvare09664152007-06-09 10:11:15 -0400263without PEC), which is not what we want. Thus, PEC is explicitly disabled
Jean Delvarec3df5802005-10-26 21:39:40 +0200264on SMBus Send Byte transactions in the lm90 driver.
265
266PEC on byte data transactions represents a significant increase in bandwidth
267usage (+33% for writes, +25% for reads) in normal conditions. With the need
268to use two SMBus transaction for reads, this overhead jumps to +50%. Worse,
269two transactions will typically mean twice as much delay waiting for
270transaction completion, effectively doubling the register cache refresh time.
271I guess reliability comes at a price, but it's quite expensive this time.
272
273So, as not everyone might enjoy the slowdown, PEC can be disabled through
274sysfs. Just write 0 to the "pec" file and PEC will be disabled. Write 1
275to that file to enable PEC again.