Merge tag 'tty-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty / serial driver updates from Greg KH:
 "Here is the big set of TTY/Serial driver updates and cleanups for
  6.9-rc1. Included in here are:

   - more tty cleanups from Jiri

   - loads of 8250 driver cleanups from Andy

   - max310x driver updates

   - samsung serial driver updates

   - uart_prepare_sysrq_char() updates for many drivers

   - platform driver remove callback void cleanups

   - stm32 driver updates

   - other small tty/serial driver updates

  All of these have been in linux-next for a long time with no reported
  issues"

* tag 'tty-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits)
  dt-bindings: serial: stm32: add power-domains property
  serial: 8250_dw: Replace ACPI device check by a quirk
  serial: Lock console when calling into driver before registration
  serial: 8250_uniphier: Switch to use uart_read_port_properties()
  serial: 8250_tegra: Switch to use uart_read_port_properties()
  serial: 8250_pxa: Switch to use uart_read_port_properties()
  serial: 8250_omap: Switch to use uart_read_port_properties()
  serial: 8250_of: Switch to use uart_read_port_properties()
  serial: 8250_lpc18xx: Switch to use uart_read_port_properties()
  serial: 8250_ingenic: Switch to use uart_read_port_properties()
  serial: 8250_dw: Switch to use uart_read_port_properties()
  serial: 8250_bcm7271: Switch to use uart_read_port_properties()
  serial: 8250_bcm2835aux: Switch to use uart_read_port_properties()
  serial: 8250_aspeed_vuart: Switch to use uart_read_port_properties()
  serial: port: Introduce a common helper to read properties
  serial: core: Add UPIO_UNKNOWN constant for unknown port type
  serial: core: Move struct uart_port::quirks closer to possible values
  serial: sh-sci: Call sci_serial_{in,out}() directly
  serial: core: only stop transmit when HW fifo is empty
  serial: pch: Use uart_prepare_sysrq_char().
  ...

1 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/w1/masters/w1-uart.rst b/Documentation/w1/masters/w1-uart.rst
new file mode 100644
index 00000000000000..8d0f122178d4d6
--- /dev/null
+++ b/Documentation/w1/masters/w1-uart.rst
@@ -0,0 +1,54 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+=====================
+Kernel driver w1-uart
+=====================
+
+Author: Christoph Winklhofer <cj.winklhofer@gmail.com>
+
+
+Description
+-----------
+
+UART 1-Wire bus driver. The driver utilizes the UART interface via the
+Serial Device Bus to create the 1-Wire timing patterns as described in
+the document `"Using a UART to Implement a 1-Wire Bus Master"`_.
+
+.. _"Using a UART to Implement a 1-Wire Bus Master": 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 0x80 is used for a
+Write-0 operation (low time 69.6us) and the byte 0xff for Read-0, Read-1
+and Write-1 (low time 8.7us).
+
+The default baud-rate for reset and presence detection is 9600 and for
+a 1-Wire read or write operation 115200. In case the actual baud-rate
+is different from the requested one, the transmitted byte is adapted
+to generate the 1-Wire timing patterns.
+
+
+Usage
+-----
+
+Specify the UART 1-wire bus in the device tree by adding the single child
+onewire to the serial node (e.g. uart0). For example:
+::
+
+  @uart0 {
+    ...
+    onewire {
+      compatible = "w1-uart";
+    };
+  };