Hello! Krzysztof, thank your very much for your feedback! 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. Version 1 - In v1, 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. Is this the correct direction or should the baud-rate be specified in the device-tree? Alternatively, it could make sense to specify the minimum and maximum times for the 1-Wire operations in the device-tree, instead of using hard-coded ones similar as in "Figure 11. Configuration tab" of the linked document "Using UART to Implement a 1-Wire Bus Master". - In addition, the received byte is now protected with a mutex - instead of the atomic, which I used before due to the concurrent store and load. - 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. Changes: - support different baud-rates - fix variable names, errno-returns, wrong define CONFIG_OF - fix log flooding - fix locking problem for serdev-receive and w1-master reset/touch - fix driver remove (error-path for rxtx-function) - add documentation for dt-binding 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 - Patch 2: 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 (2): dt-bindings: w1: UART 1-wire bus w1: add UART w1 bus driver .../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 ++++++++++++++++++ 6 files changed, 416 insertions(+) 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 -- 2.43.0
