ae1f3df434
only gpiobus configured via FDT is supported. Bus enumeration is supported. Devices are created for each device found. 1-Wire temperature controllers are supported, but other drivers could be written. Temperatures are polled and reported via a sysctl. Errors are reported via sysctl counters. Mis-wired bus detection is included for more trouble shooting. See ow(4), owc(4) and ow_temp(4) for details of what's supported and known issues. This has been tested on Raspberry Pi-B, Pi2 and Beagle Bone Black with up to 7 devices. Differential Revision: https://reviews.freebsd.org/D2956 Relnotes: yes MFC after: 2 weeks Reviewed by: loos@ (with many insightful comments)
20 lines
908 B
Plaintext
20 lines
908 B
Plaintext
Quick Design Document for 1-wire bus
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In new bus terms, 1-wire devices are attached to 1-wire buses (ow)
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which are attached to a one wire bridge (owc).
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The implementation follows the terminology used in the Maxim AN927
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Application note which defines the 1-wire bus as implemented for the
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iButton product. This is considered to be the canonical definition of
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the 1-wire bus. This means that the 1-wire bridge will implement the
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owll(9) interface. ow is one wire. ll is for Link Level to mirror the ISO
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stack terminology used by AN927. The 1-wire bus is implemented in the ow(4)
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device, which implements the own(9) interface (n for network, the layer
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described in the AN927). The presentation layer and above is the
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responsibility of the client device drivers to implement.
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Client drivers may only call the own(9) interface. The ow(4) driver
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calls the owll(9) interface and implements the own(9).
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$FreeBSD$
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