94859308a2
Some preliminary work at making use of this driver led me to implement CRC-16 checks on read and write to deal with the occasional glitchiness of the 1-Wire bus. The revised driver (attached) returns an I/O error if the CRC check fails. When reading the chip's state, either you get a valid indication or you get an I/O error. When changing its state, either the change is successful or an I/O error is returned. Signed-off-by: Scott Alfter <scott@alfter.us> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
26 lines
1 KiB
Plaintext
26 lines
1 KiB
Plaintext
w1_ds2406 kernel driver
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=======================
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Supported chips:
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* Maxim DS2406 (and other family 0x12) addressable switches
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Author: Scott Alfter <scott@alfter.us>
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Description
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-----------
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The w1_ds2406 driver allows connected devices to be switched on and off.
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These chips also provide 128 bytes of OTP EPROM, but reading/writing it is
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not supported. In TSOC-6 form, the DS2406 provides two switch outputs and
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can be provided with power on a dedicated input. In TO-92 form, it provides
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one output and uses parasitic power only.
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The driver provides two sysfs files. state is readable; it gives the
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current state of each switch, with PIO A in bit 0 and PIO B in bit 1. The
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driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to
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work with. output is writable; bits 0 and 1 control PIO A and B,
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respectively. Bits 2-7 are ignored, so it's safe to write ASCII data.
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CRCs are checked on read and write. Failed checks cause an I/O error to be
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returned. On a failed write, the switch status is not changed.
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