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Convert rs485 binding to yaml style file.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Rob Herring <robh@kernel.org>
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Whilst making an unrelated change to some Documentation, Linus sayeth:
| Afaik, even in Britain, "whilst" is unusual and considered more
| formal, and "while" is the common word.
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| [...]
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| Can we just admit that we work with computers, and we don't need to
| use þe eald Englisc spelling of words that most of the world never
| uses?
dictionary.com refers to the word as "Chiefly British", which is
probably an undesirable attribute for technical documentation.
Replace all occurrences under Documentation/ with "while".
Cc: David Howells <dhowells@redhat.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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rs485 allows for robust half-duplex serial communication. It is often
implemented by attaching an rs485 transceiver to a UART. The UART's
RTS line is wired to the transceiver's Transmit Enable pin and
determines whether the transceiver is sending or receiving.
Examples for such transceivers are Maxim MAX13451E and TI SN65HVD1781A:
https://datasheets.maximintegrated.com/en/ds/MAX13450E-MAX13451E.pdf
http://www.ti.com/lit/ds/symlink/sn65hvd1781a-q1.pdf
In the devicetree, the transceiver itself is not represented, only the
UART is. A few rs485-specific dt-bindings already exist and these go
into the UART's device node.
This commit adds a binding to set the RTS polarity. Most (if not all)
transceivers require the Transmit Enable pin be driven high for sending,
but in some cases boards may negate the pin and RTS must then be driven
low. Consequently the polarity defaults to active high but can be
inverted with the newly added "rs485-rts-active-low" binding.
Document this binding in rs485.txt and in the two drivers fsl-imx-uart
and fsl-lpuart that are about to be amended with support for it.
Curiously, the omap_serial driver defaults to active low and already
supports an "rs485-rts-active-high" binding to invert the polarity.
This is left unchanged to retain compatibility, but the binding is
herewith documented.
Cc: Mark Jackson <mpfj@newflow.co.uk>
Cc: Michał Oleszczyk <oleszczyk.m@gmail.com>
Cc: Rafael Gago Castano <rgc@hms.se>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There are a few device trees that specify one of the already optional
properties without also having the up to now required property
rs485-rts-delay. Additionally there is no technical reason to require
rs485-rts-delay and that's also what most drivers implement.
So give existing users and implementers a blessing and document
rs485-rts-delay as optional.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Corrected the word beteween to between in the file rs485.txt.
Signed-off-by: Stefan Huber <steffhip@gmail.com>
Signed-off-by: Matthias Schid <aircrach115@gmail.com>
Signed-off-by: Simon Puels <simon.puels@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Generic bindings for RS485 feature included in some UARTs.
Those bindings have to be used withing an UART device tree node.
Documentation updated to link to the bindings definition.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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