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(188-23-116-43.adsl.highway.telekom.at. [188.23.116.43]) by smtp.gmail.com with ESMTPSA id su24-20020a17090703d800b00a26ab41d0f7sm2357765ejb.26.2023.12.23.02.04.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 23 Dec 2023 02:04:13 -0800 (PST) From: Christoph Winklhofer To: krzysztof.kozlowski@linaro.org, robh+dt@kernel.org, conor+dt@kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Christoph Winklhofer Subject: [PATCH v2 0/3] w1: add UART w1 bus driver Date: Sat, 23 Dec 2023 11:04:05 +0100 Message-ID: <20231223100408.44056-1-cj.winklhofer@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hello! This patch contains a driver for a 1-Wire bus over UART. The driver utilizes the UART interface via the Serial Device Bus to create the 1-Wire timing patterns. Changes in v2: - add documentation for dt-binding - allow onewire as serial child node - support different baud-rates: The driver requests a baud-rate (9600 for reset and 115200 for write/read) and tries to adapt the transmitted byte according to the actual baud-rate returned from serdev. - fix locking problem for serdev-receive and w1-master reset/touch: The received byte is now protected with a mutex - instead of the atomic, which was used before due to the concurrent store and load. - explicit error in serdev-receive: Receiving more than one byte results in an error, since the w1-uart driver is the only writer, it writes a single-byte and should receive a single byte. - fix variable names, errno-returns, wrong define CONFIG_OF - fix log flooding - fix driver remove (error-path for rxtx-function) Krzysztof, thank your very much for your feedback! It was tested on a "Raspberry Pi 3 Model B+" with a DS18B20 and on a "Variscite DART-6UL" with a DS18S20 temperature sensor. Content: - Patch 1: device tree binding 1-Wire - Patch 2: allow onewire as serial child node - Patch 3: driver and documentation The patch was created against the w1 subsytem tree (branch w1-next): Link: https://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux-w1.git/ The checkpatch.pl script reported the following error - which I am not sure how to fix: WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? The technical details for 1-Wire over UART are in the document: Link: https://www.analog.com/en/technical-articles/using-a-uart-to-implement-a-1wire-bus-master.html In short, the UART peripheral must support full-duplex and operate in open-drain mode. The timing patterns are generated by a specific combination of baud-rate and transmitted byte, which corresponds to a 1-Wire read bit, write bit or reset pulse. For instance the timing pattern for a 1-Wire reset and presence detect uses the baud-rate 9600, i.e. 104.2 us per bit. The transmitted byte 0xf0 over UART (least significant bit first, start-bit low) sets the reset low time for 1-Wire to 521 us. A present 1-Wire device changes the received byte by pulling the line low, which is used by the driver to evaluate the result of the 1-Wire operation. Similar for a 1-Wire read bit or write bit, which uses the baud-rate 115200, i.e. 8.7 us per bit. The transmitted byte 0x00 is used for a Write-0 operation and the byte 0xff for Read-0, Read-1 and Write-1. Hope the driver is helpful. Thanks, Christoph Christoph Winklhofer (3): dt-bindings: w1: UART 1-Wire bus dt-bindings: serial: allow onewire as child node w1: add UART w1 bus driver .../devicetree/bindings/serial/serial.yaml | 2 +- .../devicetree/bindings/w1/w1-uart.yaml | 44 +++ Documentation/w1/masters/index.rst | 1 + Documentation/w1/masters/w1-uart.rst | 53 +++ drivers/w1/masters/Kconfig | 10 + drivers/w1/masters/Makefile | 1 + drivers/w1/masters/w1-uart.c | 307 ++++++++++++++++++ 7 files changed, 417 insertions(+), 1 deletion(-) create mode 100644 Documentation/devicetree/bindings/w1/w1-uart.yaml create mode 100644 Documentation/w1/masters/w1-uart.rst create mode 100644 drivers/w1/masters/w1-uart.c base-commit: efc19c44aa442197ddcbb157c6ca54a56eba8c4e