xref: /openbmc/linux/Documentation/hwmon/lm95245.rst (revision 4b4193256c8d3bc3a5397b5cd9494c2ad386317d)
17ebd8b66SMauro Carvalho ChehabKernel driver lm95245
27ebd8b66SMauro Carvalho Chehab=====================
37ebd8b66SMauro Carvalho Chehab
47ebd8b66SMauro Carvalho ChehabSupported chips:
57ebd8b66SMauro Carvalho Chehab
67ebd8b66SMauro Carvalho Chehab  * TI LM95235
77ebd8b66SMauro Carvalho Chehab
87ebd8b66SMauro Carvalho Chehab    Addresses scanned: I2C 0x18, 0x29, 0x4c
97ebd8b66SMauro Carvalho Chehab
107ebd8b66SMauro Carvalho Chehab    Datasheet: Publicly available at the TI website
117ebd8b66SMauro Carvalho Chehab
12*ad736c1aSAlexander A. Klimov	       https://www.ti.com/lit/ds/symlink/lm95235.pdf
137ebd8b66SMauro Carvalho Chehab
147ebd8b66SMauro Carvalho Chehab  * TI / National Semiconductor LM95245
157ebd8b66SMauro Carvalho Chehab
167ebd8b66SMauro Carvalho Chehab    Addresses scanned: I2C 0x18, 0x19, 0x29, 0x4c, 0x4d
177ebd8b66SMauro Carvalho Chehab
187ebd8b66SMauro Carvalho Chehab    Datasheet: Publicly available at the TI website
197ebd8b66SMauro Carvalho Chehab
20*ad736c1aSAlexander A. Klimov	       https://www.ti.com/lit/ds/symlink/lm95245.pdf
217ebd8b66SMauro Carvalho Chehab
227ebd8b66SMauro Carvalho ChehabAuthor: Alexander Stein <alexander.stein@systec-electronic.com>
237ebd8b66SMauro Carvalho Chehab
247ebd8b66SMauro Carvalho ChehabDescription
257ebd8b66SMauro Carvalho Chehab-----------
267ebd8b66SMauro Carvalho Chehab
277ebd8b66SMauro Carvalho ChehabLM95235 and LM95245 are 11-bit digital temperature sensors with a 2-wire System
287ebd8b66SMauro Carvalho ChehabManagement Bus (SMBus) interface and TruTherm technology that can monitor
297ebd8b66SMauro Carvalho Chehabthe temperature of a remote diode as well as its own temperature.
307ebd8b66SMauro Carvalho ChehabThe chips can be used to very accurately monitor the temperature of
317ebd8b66SMauro Carvalho Chehabexternal devices such as microprocessors.
327ebd8b66SMauro Carvalho Chehab
337ebd8b66SMauro Carvalho ChehabAll temperature values are given in millidegrees Celsius. Local temperature
347ebd8b66SMauro Carvalho Chehabis given within a range of -127 to +127.875 degrees. Remote temperatures are
357ebd8b66SMauro Carvalho Chehabgiven within a range of -127 to +255 degrees. Resolution depends on
367ebd8b66SMauro Carvalho Chehabtemperature input and range.
377ebd8b66SMauro Carvalho Chehab
387ebd8b66SMauro Carvalho ChehabEach sensor has its own critical limit. Additionally, there is a relative
397ebd8b66SMauro Carvalho Chehabhysteresis value common to both critical limits. To make life easier to
407ebd8b66SMauro Carvalho Chehabuser-space applications, two absolute values are exported, one for each
417ebd8b66SMauro Carvalho Chehabchannel, but these values are of course linked. Only the local hysteresis
427ebd8b66SMauro Carvalho Chehabcan be set from user-space, and the same delta applies to the remote
437ebd8b66SMauro Carvalho Chehabhysteresis.
447ebd8b66SMauro Carvalho Chehab
457ebd8b66SMauro Carvalho ChehabThe lm95245 driver can change its update interval to a fixed set of values.
467ebd8b66SMauro Carvalho ChehabIt will round up to the next selectable interval. See the datasheet for exact
477ebd8b66SMauro Carvalho Chehabvalues. Reading sensor values more often will do no harm, but will return
487ebd8b66SMauro Carvalho Chehab'old' values.
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