[PATCH v4 0/3] w1: add UART w1 bus driver

[PATCH v4 0/3] w1: add UART w1 bus driver

[Christoph Winklhofer via B4 Relay]

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 v4:
- rework baud-rate configuration: also check max bit-time, support higher
  baud-rates by adding a delay to complete 1-Wire cycle.
- dt-binding w1-uart: specify baud-rates for 1-Wire operations
- Link to v3: https://lore.kernel.org/r/20240105-w1-uart-v3-0-8687093b2e76@gmail.com

Changes in v3:
- improve baud-rate configuration: use specific limits for 1-Wire
  reset, touch-0 and touch-1 operation, compute in nanoseconds.
- remove unused header atomic.h
- use function instead of macro to compute bit-time from baud-rate
- switch to b4 util to publish patch: missing recipients
- Link to v2: https://lore.kernel.org/lkml/20231223100408.44056-1-cj.winklhofer@gmail.com

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)
- Link to v1: https://lore.kernel.org/all/20231217122004.42795-1-cj.winklhofer@gmail.com
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

--
2.43.0

base-commit: efc19c44aa442197ddcbb157c6ca54a56eba8c4e
---
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 +-
 Documentation/devicetree/bindings/w1/w1-uart.yaml  |  62 ++++
 Documentation/w1/masters/index.rst                 |   1 +
 Documentation/w1/masters/w1-uart.rst               |  54 +++
 drivers/w1/masters/Kconfig                         |  10 +
 drivers/w1/masters/Makefile                        |   1 +
 drivers/w1/masters/w1-uart.c                       | 398 +++++++++++++++++++++
 7 files changed, 527 insertions(+), 1 deletion(-)
---
base-commit: efc19c44aa442197ddcbb157c6ca54a56eba8c4e
change-id: 20240104-w1-uart-ee8685a15a50

Best regards,
-- 
Christoph Winklhofer <cj.winklhofer@gmail.com>

[PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Christoph Winklhofer via B4 Relay]

From: Christoph Winklhofer <cj.winklhofer@gmail.com>

Add device tree binding for UART 1-Wire bus.

Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
---
 Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
new file mode 100644
index 000000000000..6b90693b2ca0
--- /dev/null
+++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: UART 1-Wire Bus
+
+maintainers:
+  - Christoph Winklhofer <cj.winklhofer@gmail.com>
+
+description: |
+  UART 1-wire bus. Utilizes the UART interface via the Serial Device Bus
+  to create the 1-Wire timing patterns.
+
+  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.
+
+  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.
+
+  https://www.analog.com/en/technical-articles/using-a-uart-to-implement-a-1wire-bus-master.html
+
+
+properties:
+  compatible:
+    const: w1-uart
+
+  reset-speed:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 9600
+    description: |
+      The baud rate for the 1-Wire reset and presence detect.
+
+  touch_0-speed:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 115200
+    description: |
+      The baud rate for the 1-Wire write-0 cycle (touch bit 0).
+
+  touch_1-speed:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 115200
+    description: |
+      The baud rate for the 1-Wire write-1 and read cycle (touch bit 1).
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    serial {
+      onewire {
+        compatible = "w1-uart";
+      };
+    };

-- 
2.43.0

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Rob Herring]

On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
> Add device tree binding for UART 1-Wire bus.
> 
> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
> ---
>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> new file mode 100644
> index 000000000000..6b90693b2ca0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> @@ -0,0 +1,62 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: UART 1-Wire Bus
> +
> +maintainers:
> +  - Christoph Winklhofer <cj.winklhofer@gmail.com>
> +
> +description: |
> +  UART 1-wire bus. Utilizes the UART interface via the Serial Device Bus
> +  to create the 1-Wire timing patterns.
> +
> +  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.
> +
> +  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.
> +
> +  https://www.analog.com/en/technical-articles/using-a-uart-to-implement-a-1wire-bus-master.html
> +
> +
> +properties:
> +  compatible:
> +    const: w1-uart
> +
> +  reset-speed:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 9600
> +    description: |

Don't need '|' if no formatting

> +      The baud rate for the 1-Wire reset and presence detect.
> +
> +  touch_0-speed:

Don't use '_' in property names.

I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
here. I assume these are low and high times which are a function of the 
baudrate.


> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 115200
> +    description: |
> +      The baud rate for the 1-Wire write-0 cycle (touch bit 0).
> +
> +  touch_1-speed:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    default: 115200
> +    description: |
> +      The baud rate for the 1-Wire write-1 and read cycle (touch bit 1).
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false

w1.txt says there can be a child node for the 1-wire device. You need 
'type: object'. Or w1.txt needs to be converted to schema and referenced 
here (along with using unevaluatedProperties here instead).

Rob

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Christoph Winklhofer]

On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
> > Add device tree binding for UART 1-Wire bus.
> > 
> > Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
> > ---
> >  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
> >  1 file changed, 62 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> > new file mode 100644
> > index 000000000000..6b90693b2ca0
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> > @@ -0,0 +1,62 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
...
> > +properties:
> > +  compatible:
> > +    const: w1-uart
> > +
> > +  reset-speed:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    default: 9600
> > +    description: |
> 
> Don't need '|' if no formatting
> 

Ok.

> > +      The baud rate for the 1-Wire reset and presence detect.
> > +
> > +  touch_0-speed:
> 
> Don't use '_' in property names.
> 
> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
> here. I assume these are low and high times which are a function of the 
> baudrate.
> 

I change the name to 'write-0-speed' and 'write-1-speed'. The function
in the w1-framework is named 'touch_bit' - therefore the previous
naming. 

It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
(write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
reads a 0-Bit or 1-Bit (write-1-speed).

> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    default: 115200
> > +    description: |
> > +      The baud rate for the 1-Wire write-0 cycle (touch bit 0).
> > +
> > +  touch_1-speed:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    default: 115200
> > +    description: |
> > +      The baud rate for the 1-Wire write-1 and read cycle (touch bit 1).
> > +
> > +required:
> > +  - compatible
> > +
> > +additionalProperties: false
> 
> w1.txt says there can be a child node for the 1-wire device. You need 
> 'type: object'. Or w1.txt needs to be converted to schema and referenced 
> here (along with using unevaluatedProperties here instead).
> 
> Rob

Will change it to type object. However, I also tried to convert w1.txt
to w1.yaml - I am not quite sure, so I add an excerpt of my attempt.
The example in w1.txt builds fine. Is oneOf allowed as a top-level
property, the documentation only mentions allOf?
Only one child should be allowed, but I did not find a way to restrict
this.

# w1-uart.yaml:
unevaluatedProperties:
  $ref: w1.yaml

# w1.yaml:
properties:
  compatible:
    enum:
      - maxim,ds2760

oneOf:
  - $ref: /schemas/power/supply/maxim,ds2760.yaml

unevaluatedProperties: false
#

Thank you for the review!

Kind regards,
Christoph

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Krzysztof Kozlowski]

On 13/01/2024 19:04, Christoph Winklhofer wrote:
> On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
>> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
>>> Add device tree binding for UART 1-Wire bus.
>>>
>>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
>>> ---
>>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
>>>  1 file changed, 62 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
>>> new file mode 100644
>>> index 000000000000..6b90693b2ca0
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
>>> @@ -0,0 +1,62 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> ...
>>> +properties:
>>> +  compatible:
>>> +    const: w1-uart
>>> +
>>> +  reset-speed:
>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    default: 9600
>>> +    description: |
>>
>> Don't need '|' if no formatting
>>
> 
> Ok.
> 
>>> +      The baud rate for the 1-Wire reset and presence detect.
>>> +
>>> +  touch_0-speed:
>>
>> Don't use '_' in property names.
>>
>> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
>> here. I assume these are low and high times which are a function of the 
>> baudrate.
>>
> 
> I change the name to 'write-0-speed' and 'write-1-speed'. The function
> in the w1-framework is named 'touch_bit' - therefore the previous
> naming. 
> 
> It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
> (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
> reads a 0-Bit or 1-Bit (write-1-speed).


Then probably -bps:
https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml


> 
>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    default: 115200
>>> +    description: |
>>> +      The baud rate for the 1-Wire write-0 cycle (touch bit 0).
>>> +
>>> +  touch_1-speed:
>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> +    default: 115200
>>> +    description: |
>>> +      The baud rate for the 1-Wire write-1 and read cycle (touch bit 1).
>>> +
>>> +required:
>>> +  - compatible
>>> +
>>> +additionalProperties: false
>>
>> w1.txt says there can be a child node for the 1-wire device. You need 
>> 'type: object'. Or w1.txt needs to be converted to schema and referenced 
>> here (along with using unevaluatedProperties here instead).
>>
>> Rob
> 
> Will change it to type object. However, I also tried to convert w1.txt
> to w1.yaml - I am not quite sure, so I add an excerpt of my attempt.
> The example in w1.txt builds fine. Is oneOf allowed as a top-level
> property, the documentation only mentions allOf?
> Only one child should be allowed, but I did not find a way to restrict
> this.
> 
> # w1-uart.yaml:
> unevaluatedProperties:
>   $ref: w1.yaml
> 
> # w1.yaml:
> properties:
>   compatible:
>     enum:
>       - maxim,ds2760

w1 describes entire class of the devices, so it should not have
compatibles. Look how other buses do it.
> 
> oneOf:
>   - $ref: /schemas/power/supply/maxim,ds2760.yaml
> 
> unevaluatedProperties: false


Best regards,
Krzysztof

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Christoph Winklhofer]

On Sun, Jan 14, 2024 at 11:54:48AM +0100, Krzysztof Kozlowski wrote:
> On 13/01/2024 19:04, Christoph Winklhofer wrote:
> > On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
> >> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
> >>> Add device tree binding for UART 1-Wire bus.
> >>>
> >>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
> >>> ---
> >>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
> >>>  1 file changed, 62 insertions(+)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>> new file mode 100644
> >>> index 000000000000..6b90693b2ca0
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>> @@ -0,0 +1,62 @@
> >>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > ...
> >>> +properties:
> >>> +  compatible:
> >>> +    const: w1-uart
> >>> +
> >>> +  reset-speed:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    default: 9600
> >>> +    description: |
> >>
> >> Don't need '|' if no formatting
> >>
> > 
> > Ok.
> > 
> >>> +      The baud rate for the 1-Wire reset and presence detect.
> >>> +
> >>> +  touch_0-speed:
> >>
> >> Don't use '_' in property names.
> >>
> >> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
> >> here. I assume these are low and high times which are a function of the 
> >> baudrate.
> >>
> > 
> > I change the name to 'write-0-speed' and 'write-1-speed'. The function
> > in the w1-framework is named 'touch_bit' - therefore the previous
> > naming. 
> > 
> > It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
> > (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
> > reads a 0-Bit or 1-Bit (write-1-speed).
> 
> 
> Then probably -bps:
> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml

The serial.yaml uses prefix -speed for the baud rate but I can change it
to -bps.

> 
> > 
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    default: 115200
> >>> +    description: |
> >>> +      The baud rate for the 1-Wire write-0 cycle (touch bit 0).
> >>> +
> >>> +  touch_1-speed:
> >>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>> +    default: 115200
> >>> +    description: |
> >>> +      The baud rate for the 1-Wire write-1 and read cycle (touch bit 1).
> >>> +
> >>> +required:
> >>> +  - compatible
> >>> +
> >>> +additionalProperties: false
> >>
> >> w1.txt says there can be a child node for the 1-wire device. You need 
> >> 'type: object'. Or w1.txt needs to be converted to schema and referenced 
> >> here (along with using unevaluatedProperties here instead).
> >>
> >> Rob
> > 
> > Will change it to type object. However, I also tried to convert w1.txt
> > to w1.yaml - I am not quite sure, so I add an excerpt of my attempt.
> > The example in w1.txt builds fine. Is oneOf allowed as a top-level
> > property, the documentation only mentions allOf?
> > Only one child should be allowed, but I did not find a way to restrict
> > this.
> > 
> > # w1-uart.yaml:
> > unevaluatedProperties:
> >   $ref: w1.yaml
> > 
> > # w1.yaml:
> > properties:
> >   compatible:
> >     enum:
> >       - maxim,ds2760
> 
> w1 describes entire class of the devices, so it should not have
> compatibles. Look how other buses do it.

Thanks for the hint, looked at serial.yaml and usb.yaml. Hence w1.yaml
should describe the properties common to all w1 bus controllers
(property for child device) and w1-uart.yaml references it in allOf,
like:

# w1.yaml
patternProperties:
  ".*":
    if:
      type: object
    then:
      description: Devices are listed...
      properties:
	compatible:
      required:
	- compatible
additionalProperties: true

# w1-uart.yaml
allOf:
 - $ref: w1.yaml#
unevaluatedProperties: false

Kind regards,
Christoph

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Krzysztof Kozlowski]

On 14/01/2024 15:47, Christoph Winklhofer wrote:
> On Sun, Jan 14, 2024 at 11:54:48AM +0100, Krzysztof Kozlowski wrote:
>> On 13/01/2024 19:04, Christoph Winklhofer wrote:
>>> On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
>>>> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
>>>>> Add device tree binding for UART 1-Wire bus.
>>>>>
>>>>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
>>>>> ---
>>>>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
>>>>>  1 file changed, 62 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
>>>>> new file mode 100644
>>>>> index 000000000000..6b90693b2ca0
>>>>> --- /dev/null
>>>>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
>>>>> @@ -0,0 +1,62 @@
>>>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>>>> +%YAML 1.2
>>>>> +---
>>>>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> ...
>>>>> +properties:
>>>>> +  compatible:
>>>>> +    const: w1-uart
>>>>> +
>>>>> +  reset-speed:
>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>> +    default: 9600
>>>>> +    description: |
>>>>
>>>> Don't need '|' if no formatting
>>>>
>>>
>>> Ok.
>>>
>>>>> +      The baud rate for the 1-Wire reset and presence detect.
>>>>> +
>>>>> +  touch_0-speed:
>>>>
>>>> Don't use '_' in property names.
>>>>
>>>> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
>>>> here. I assume these are low and high times which are a function of the 
>>>> baudrate.
>>>>
>>>
>>> I change the name to 'write-0-speed' and 'write-1-speed'. The function
>>> in the w1-framework is named 'touch_bit' - therefore the previous
>>> naming. 
>>>
>>> It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
>>> (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
>>> reads a 0-Bit or 1-Bit (write-1-speed).
>>
>>
>> Then probably -bps:
>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
> 
> The serial.yaml uses prefix -speed for the baud rate but I can change it
> to -bps.

Do you reference serial.yaml?

> 


Best regards,
Krzysztof

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Christoph Winklhofer]

On Sun, Jan 14, 2024 at 04:55:42PM +0100, Krzysztof Kozlowski wrote:
> On 14/01/2024 15:47, Christoph Winklhofer wrote:
> > On Sun, Jan 14, 2024 at 11:54:48AM +0100, Krzysztof Kozlowski wrote:
> >> On 13/01/2024 19:04, Christoph Winklhofer wrote:
> >>> On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
> >>>> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
> >>>>> Add device tree binding for UART 1-Wire bus.
> >>>>>
> >>>>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
> >>>>> ---
> >>>>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
> >>>>>  1 file changed, 62 insertions(+)
> >>>>>
> >>>>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>>>> new file mode 100644
> >>>>> index 000000000000..6b90693b2ca0
> >>>>> --- /dev/null
> >>>>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>>>> @@ -0,0 +1,62 @@
> >>>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> >>>>> +%YAML 1.2
> >>>>> +---
> >>>>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
> >>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> ...
> >>>>> +properties:
> >>>>> +  compatible:
> >>>>> +    const: w1-uart
> >>>>> +
> >>>>> +  reset-speed:
> >>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>>>> +    default: 9600
> >>>>> +    description: |
> >>>>
> >>>> Don't need '|' if no formatting
> >>>>
> >>>
> >>> Ok.
> >>>
> >>>>> +      The baud rate for the 1-Wire reset and presence detect.
> >>>>> +
> >>>>> +  touch_0-speed:
> >>>>
> >>>> Don't use '_' in property names.
> >>>>
> >>>> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
> >>>> here. I assume these are low and high times which are a function of the 
> >>>> baudrate.
> >>>>
> >>>
> >>> I change the name to 'write-0-speed' and 'write-1-speed'. The function
> >>> in the w1-framework is named 'touch_bit' - therefore the previous
> >>> naming. 
> >>>
> >>> It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
> >>> (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
> >>> reads a 0-Bit or 1-Bit (write-1-speed).
> >>
> >>
> >> Then probably -bps:
> >> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
> > 
> > The serial.yaml uses prefix -speed for the baud rate but I can change it
> > to -bps.
> 
> Do you reference serial.yaml?
> 

No, serial.yaml is not referenced but 'onewire' will be a child-node of
a serial-device which already defines baud rate related properties
with -speed (e.g. max-speed although not used in w1-uart). Hence, I
thought -speed is typically used for baud rates.

Thanks,
Christoph

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Krzysztof Kozlowski]

On 15/01/2024 18:36, Christoph Winklhofer wrote:
> On Sun, Jan 14, 2024 at 04:55:42PM +0100, Krzysztof Kozlowski wrote:
>> On 14/01/2024 15:47, Christoph Winklhofer wrote:
>>> On Sun, Jan 14, 2024 at 11:54:48AM +0100, Krzysztof Kozlowski wrote:
>>>> On 13/01/2024 19:04, Christoph Winklhofer wrote:
>>>>> On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
>>>>>> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
>>>>>>> Add device tree binding for UART 1-Wire bus.
>>>>>>>
>>>>>>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
>>>>>>> ---
>>>>>>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
>>>>>>>  1 file changed, 62 insertions(+)
>>>>>>>
>>>>>>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..6b90693b2ca0
>>>>>>> --- /dev/null
>>>>>>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
>>>>>>> @@ -0,0 +1,62 @@
>>>>>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>>>>>> +%YAML 1.2
>>>>>>> +---
>>>>>>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
>>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>> ...
>>>>>>> +properties:
>>>>>>> +  compatible:
>>>>>>> +    const: w1-uart
>>>>>>> +
>>>>>>> +  reset-speed:
>>>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>>>> +    default: 9600
>>>>>>> +    description: |
>>>>>>
>>>>>> Don't need '|' if no formatting
>>>>>>
>>>>>
>>>>> Ok.
>>>>>
>>>>>>> +      The baud rate for the 1-Wire reset and presence detect.
>>>>>>> +
>>>>>>> +  touch_0-speed:
>>>>>>
>>>>>> Don't use '_' in property names.
>>>>>>
>>>>>> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
>>>>>> here. I assume these are low and high times which are a function of the 
>>>>>> baudrate.
>>>>>>
>>>>>
>>>>> I change the name to 'write-0-speed' and 'write-1-speed'. The function
>>>>> in the w1-framework is named 'touch_bit' - therefore the previous
>>>>> naming. 
>>>>>
>>>>> It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
>>>>> (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
>>>>> reads a 0-Bit or 1-Bit (write-1-speed).
>>>>
>>>>
>>>> Then probably -bps:
>>>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
>>>
>>> The serial.yaml uses prefix -speed for the baud rate but I can change it
>>> to -bps.
>>
>> Do you reference serial.yaml?
>>
> 
> No, serial.yaml is not referenced but 'onewire' will be a child-node of
> a serial-device which already defines baud rate related properties
> with -speed (e.g. max-speed although not used in w1-uart). Hence, I
> thought -speed is typically used for baud rates.

Ah, it defines max-speed for childre, so for onewire. Re-using that
property would make sense, but since you are defining completely new
properties, let's use proper (-bps) naming.

I still wonder, why would you use different baud rates for these three
different operations?

Best regards,
Krzysztof

Re: [PATCH v4 1/3] dt-bindings: w1: UART 1-Wire bus

[Christoph Winklhofer]

On Mon, Jan 15, 2024 at 07:02:55PM +0100, Krzysztof Kozlowski wrote:
> On 15/01/2024 18:36, Christoph Winklhofer wrote:
> > On Sun, Jan 14, 2024 at 04:55:42PM +0100, Krzysztof Kozlowski wrote:
> >> On 14/01/2024 15:47, Christoph Winklhofer wrote:
> >>> On Sun, Jan 14, 2024 at 11:54:48AM +0100, Krzysztof Kozlowski wrote:
> >>>> On 13/01/2024 19:04, Christoph Winklhofer wrote:
> >>>>> On Fri, Jan 12, 2024 at 07:39:17PM -0600, Rob Herring wrote:
> >>>>>> On Sat, Jan 06, 2024 at 05:02:24PM +0100, Christoph Winklhofer wrote:
> >>>>>>> Add device tree binding for UART 1-Wire bus.
> >>>>>>>
> >>>>>>> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
> >>>>>>> ---
> >>>>>>>  Documentation/devicetree/bindings/w1/w1-uart.yaml | 62 +++++++++++++++++++++++
> >>>>>>>  1 file changed, 62 insertions(+)
> >>>>>>>
> >>>>>>> diff --git a/Documentation/devicetree/bindings/w1/w1-uart.yaml b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>>>>>> new file mode 100644
> >>>>>>> index 000000000000..6b90693b2ca0
> >>>>>>> --- /dev/null
> >>>>>>> +++ b/Documentation/devicetree/bindings/w1/w1-uart.yaml
> >>>>>>> @@ -0,0 +1,62 @@
> >>>>>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> >>>>>>> +%YAML 1.2
> >>>>>>> +---
> >>>>>>> +$id: http://devicetree.org/schemas/w1/w1-uart.yaml#
> >>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>>>> ...
> >>>>>>> +properties:
> >>>>>>> +  compatible:
> >>>>>>> +    const: w1-uart
> >>>>>>> +
> >>>>>>> +  reset-speed:
> >>>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>>>>>> +    default: 9600
> >>>>>>> +    description: |
> >>>>>>
> >>>>>> Don't need '|' if no formatting
> >>>>>>
> >>>>>
> >>>>> Ok.
> >>>>>
> >>>>>>> +      The baud rate for the 1-Wire reset and presence detect.
> >>>>>>> +
> >>>>>>> +  touch_0-speed:
> >>>>>>
> >>>>>> Don't use '_' in property names.
> >>>>>>
> >>>>>> I'm somewhat familar with 1-wire, but I don't get what 'touch' means 
> >>>>>> here. I assume these are low and high times which are a function of the 
> >>>>>> baudrate.
> >>>>>>
> >>>>>
> >>>>> I change the name to 'write-0-speed' and 'write-1-speed'. The function
> >>>>> in the w1-framework is named 'touch_bit' - therefore the previous
> >>>>> naming. 
> >>>>>
> >>>>> It is the baud-rate used in the 1-Wire cycle to write a 0-Bit
> >>>>> (write-0-speed) and to perform a 1-Wire cycle that writes a 1-Bit and
> >>>>> reads a 0-Bit or 1-Bit (write-1-speed).
> >>>>
> >>>>
> >>>> Then probably -bps:
> >>>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
> >>>
> >>> The serial.yaml uses prefix -speed for the baud rate but I can change it
> >>> to -bps.
> >>
> >> Do you reference serial.yaml?
> >>
> > 
> > No, serial.yaml is not referenced but 'onewire' will be a child-node of
> > a serial-device which already defines baud rate related properties
> > with -speed (e.g. max-speed although not used in w1-uart). Hence, I
> > thought -speed is typically used for baud rates.
> 
> Ah, it defines max-speed for childre, so for onewire. Re-using that
> property would make sense, but since you are defining completely new
> properties, let's use proper (-bps) naming.
> 

Ok.

> I still wonder, why would you use different baud rates for these three
> different operations?

The timing for the pulse on the 1-Wire bus, to perform a 1-Wire reset or
read/write is too different to use the same baud rate for them. The
pulse can only be generated with the transmission of a single byte (to
initiate the operation and to evaluate the response), since every UART
packet starts low and ends high, only a limited set of baud rates are
possible.

Read-0/1 and Write-1 have the same low-time and therefore share the same
baud rate setting, actually this baud could be higher. Otherwise, for
Write-0 the maximum baud-rate is somewhere near 115200.

The table lists the low-time range for the 1-Wire standard speed
(overdrive is currently not implemented by the driver):

  Operation | Low-Time (usec) | Baud rate (default)
  ----------+-----------------+--------------------
  Reset     | 480 - 640       | 9600
  Read-0/1  |   5 -  15       | 115200
  Write-1   |   5 -  15       | 115200
  Write-0   |  60 - 120       | 115200

I thought it makes sense to have the option to overwrite the default
baud rates. Alternatively, the driver could probe a fixed set of
different baud rates that are able to generate the timing patterns.
Initially, the driver always used 9600 and 115200 - however some UART
devices may not support these bauds. Now the driver requests a baud rate
and checks if it can create the timing pattern with the returned one.

Kind regards,
Christoph

[PATCH v4 2/3] dt-bindings: serial: allow onewire as child node

[Christoph Winklhofer via B4 Relay]

From: Christoph Winklhofer <cj.winklhofer@gmail.com>

The UART 1-Wire bus utilizes the Serial Device Bus to create the 1-wire
timing patterns.

Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
---
 Documentation/devicetree/bindings/serial/serial.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/serial/serial.yaml b/Documentation/devicetree/bindings/serial/serial.yaml
index 65804ca274ae..ffc9198ae214 100644
--- a/Documentation/devicetree/bindings/serial/serial.yaml
+++ b/Documentation/devicetree/bindings/serial/serial.yaml
@@ -88,7 +88,7 @@ properties:
       TX FIFO threshold configuration (in bytes).
 
 patternProperties:
-  "^(bluetooth|bluetooth-gnss|gnss|gps|mcu)$":
+  "^(bluetooth|bluetooth-gnss|gnss|gps|mcu|onewire)$":
     if:
       type: object
     then:

-- 
2.43.0

Re: [PATCH v4 2/3] dt-bindings: serial: allow onewire as child node

[Rob Herring]

On Sat, 06 Jan 2024 17:02:25 +0100, Christoph Winklhofer wrote:
> The UART 1-Wire bus utilizes the Serial Device Bus to create the 1-wire
> timing patterns.
> 
> Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
> ---
>  Documentation/devicetree/bindings/serial/serial.yaml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Acked-by: Rob Herring <robh@kernel.org>

[PATCH v4 3/3] w1: add UART w1 bus driver

[Christoph Winklhofer via B4 Relay]

From: Christoph Winklhofer <cj.winklhofer@gmail.com>

Add a UART 1-Wire bus driver. The driver utilizes the UART interface via
the Serial Device Bus to create the 1-Wire timing patterns. The driver
was tested on a "Raspberry Pi 3B" with a DS18B20 and on a "Variscite
DART-6UL" with a DS18S20 temperature sensor.

The 1-Wire timing pattern and the corresponding UART baud-rate with the
interpretation of the transferred bytes are described 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.

Signed-off-by: Christoph Winklhofer <cj.winklhofer@gmail.com>
---
 Documentation/w1/masters/index.rst   |   1 +
 Documentation/w1/masters/w1-uart.rst |  54 +++++
 drivers/w1/masters/Kconfig           |  10 +
 drivers/w1/masters/Makefile          |   1 +
 drivers/w1/masters/w1-uart.c         | 398 +++++++++++++++++++++++++++++++++++
 5 files changed, 464 insertions(+)

diff --git a/Documentation/w1/masters/index.rst b/Documentation/w1/masters/index.rst
index 4442a98850ad..cc40189909fd 100644
--- a/Documentation/w1/masters/index.rst
+++ b/Documentation/w1/masters/index.rst
@@ -12,3 +12,4 @@
    mxc-w1
    omap-hdq
    w1-gpio
+   w1-uart
diff --git a/Documentation/w1/masters/w1-uart.rst b/Documentation/w1/masters/w1-uart.rst
new file mode 100644
index 000000000000..8d0f122178d4
--- /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";
+    };
+  };
diff --git a/drivers/w1/masters/Kconfig b/drivers/w1/masters/Kconfig
index 513c0b114337..e6049a75b35b 100644
--- a/drivers/w1/masters/Kconfig
+++ b/drivers/w1/masters/Kconfig
@@ -78,5 +78,15 @@ config W1_MASTER_SGI
 	  This support is also available as a module.  If so, the module
 	  will be called sgi_w1.
 
+config W1_MASTER_UART
+	tristate "UART 1-wire driver"
+	depends on SERIAL_DEV_BUS
+	help
+	  Say Y here if you want to communicate with your 1-wire devices using
+	  UART interface.
+
+	  This support is also available as a module.  If so, the module
+	  will be called w1-uart.
+
 endmenu
 
diff --git a/drivers/w1/masters/Makefile b/drivers/w1/masters/Makefile
index 6c5a21f9b88c..227f80987e69 100644
--- a/drivers/w1/masters/Makefile
+++ b/drivers/w1/masters/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_W1_MASTER_MXC)		+= mxc_w1.o
 obj-$(CONFIG_W1_MASTER_GPIO)		+= w1-gpio.o
 obj-$(CONFIG_HDQ_MASTER_OMAP)		+= omap_hdq.o
 obj-$(CONFIG_W1_MASTER_SGI)		+= sgi_w1.o
+obj-$(CONFIG_W1_MASTER_UART)		+= w1-uart.o
diff --git a/drivers/w1/masters/w1-uart.c b/drivers/w1/masters/w1-uart.c
new file mode 100644
index 000000000000..e3a1f97e2a4c
--- /dev/null
+++ b/drivers/w1/masters/w1-uart.c
@@ -0,0 +1,398 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * w1-uart - UART 1-Wire bus driver
+ *
+ * Uses the UART interface (via Serial Device Bus) to create the 1-Wire
+ * timing patterns. Implements the following 1-Wire master interface:
+ *
+ * - reset_bus: requests baud-rate 9600
+ *
+ * - touch_bit: requests baud-rate 115200
+ *
+ * Author: Christoph Winklhofer <cj.winklhofer@gmail.com>
+ */
+
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/serdev.h>
+#include <linux/w1.h>
+
+#define W1_UART_TIMEOUT msecs_to_jiffies(500)
+
+/*
+ * struct w1_uart_config - configuration for 1-Wire operation
+ *
+ * @baudrate: baud-rate returned from serdev
+ * @delay_us: delay to complete a 1-Wire cycle (in us)
+ * @tx_byte: byte to generate 1-Wire timing pattern
+ */
+struct w1_uart_config {
+	unsigned int baudrate;
+	unsigned int delay_us;
+	unsigned char tx_byte;
+};
+
+struct w1_uart_device {
+	struct serdev_device *serdev;
+	struct w1_bus_master bus;
+
+	struct w1_uart_config cfg_reset;
+	struct w1_uart_config cfg_touch_0;
+	struct w1_uart_config cfg_touch_1;
+
+	struct completion rx_byte_received;
+	unsigned char rx_byte;
+	int rx_err;
+
+	struct mutex mutex;
+};
+
+/*
+ * struct w1_uart_limits - limits for 1-Wire operations
+ *
+ * @baudrate: Requested baud-rate to create 1-Wire timing pattern
+ * @bit_min_us: minimum time for a bit (in us)
+ * @bit_max_us: maximum time for a bit (in us)
+ * @sample_us: timespan to sample 1-Wire response
+ * @cycle_us: duration of the 1-Wire cycle
+ */
+struct w1_uart_limits {
+	unsigned int baudrate;
+	unsigned int bit_min_us;
+	unsigned int bit_max_us;
+	unsigned int sample_us;
+	unsigned int cycle_us;
+};
+
+static inline unsigned int baud_to_bit_ns(unsigned int baud)
+{
+	return 1000000000 / baud;
+}
+
+static inline unsigned int to_ns(unsigned int us)
+{
+	return us * 1000;
+}
+
+/*
+ * Set baud-rate, delay and tx-byte to create a 1-Wire pulse and adapt
+ * the tx-byte according to the actual baud-rate.
+ *
+ * Reject when:
+ * - time for a bit outside min/max range
+ * - a 1-Wire response is not detectable for sent byte
+ */
+static int w1_uart_set_config(struct serdev_device *serdev,
+			      const struct w1_uart_limits *limits,
+			      struct w1_uart_config *w1cfg)
+{
+	unsigned int bits_low;
+	unsigned int bit_ns;
+	unsigned int low_ns;
+
+	w1cfg->baudrate = serdev_device_set_baudrate(serdev, limits->baudrate);
+	if (w1cfg->baudrate == 0)
+		return -EINVAL;
+
+	/* Compute in nanoseconds for accuracy */
+	bit_ns = baud_to_bit_ns(w1cfg->baudrate);
+	bits_low = to_ns(limits->bit_min_us) / bit_ns;
+	/* start bit is always low */
+	low_ns = bit_ns * (bits_low + 1);
+
+	if (low_ns < to_ns(limits->bit_min_us))
+		return -EINVAL;
+
+	if (low_ns > to_ns(limits->bit_max_us))
+		return -EINVAL;
+
+	/* 1-Wire response detectable for sent byte */
+	if (limits->sample_us > 0 &&
+	    bit_ns * 8 < low_ns + to_ns(limits->sample_us))
+		return -EINVAL;
+
+	/* delay to complete 1-Wire cycle, include start and stop-bit */
+	w1cfg->delay_us = 0;
+	if (bit_ns * 10 < to_ns(limits->cycle_us))
+		w1cfg->delay_us =
+			(to_ns(limits->cycle_us) - bit_ns * 10) / 1000;
+
+	/* byte to create 1-Wire pulse */
+	w1cfg->tx_byte = 0xff << bits_low;
+
+	return 0;
+}
+
+/*
+ * Configuration for reset and presence detect
+ * - bit_min_us is 480us, add margin and use 485us
+ * - limits for sample time 60us-75us, use 65us
+ */
+static int w1_uart_set_config_reset(struct w1_uart_device *w1dev)
+{
+	struct serdev_device *serdev = w1dev->serdev;
+	struct device_node *np = serdev->dev.of_node;
+
+	struct w1_uart_limits limits = { .baudrate = 9600,
+					 .bit_min_us = 485,
+					 .bit_max_us = 640,
+					 .sample_us = 65,
+					 .cycle_us = 960 };
+
+	of_property_read_u32(np, "reset-speed", &limits.baudrate);
+
+	return w1_uart_set_config(serdev, &limits, &w1dev->cfg_reset);
+}
+
+/*
+ * Configuration for write-0 cycle (touch bit 0)
+ * - bit_min_us is 60us, add margin and use 65us
+ * - no sampling required, sample_us = 0
+ */
+static int w1_uart_set_config_touch_0(struct w1_uart_device *w1dev)
+{
+	struct serdev_device *serdev = w1dev->serdev;
+	struct device_node *np = serdev->dev.of_node;
+
+	struct w1_uart_limits limits = { .baudrate = 115200,
+					 .bit_min_us = 65,
+					 .bit_max_us = 120,
+					 .sample_us = 0,
+					 .cycle_us = 70 };
+
+	of_property_read_u32(np, "touch_0-speed", &limits.baudrate);
+
+	return w1_uart_set_config(serdev, &limits, &w1dev->cfg_touch_0);
+}
+
+/*
+ * Configuration for write-1 and read cycle (touch bit 1)
+ * - bit_min_us is 5us, add margin and use 6us
+ * - limits for sample time 5us-15us, use 15us
+ */
+static int w1_uart_set_config_touch_1(struct w1_uart_device *w1dev)
+{
+	struct serdev_device *serdev = w1dev->serdev;
+	struct device_node *np = serdev->dev.of_node;
+
+	struct w1_uart_limits limits = { .baudrate = 115200,
+					 .bit_min_us = 6,
+					 .bit_max_us = 15,
+					 .sample_us = 15,
+					 .cycle_us = 70 };
+
+	of_property_read_u32(np, "touch_1-speed", &limits.baudrate);
+
+	return w1_uart_set_config(serdev, &limits, &w1dev->cfg_touch_1);
+}
+
+/*
+ * Configure and open the serial device
+ */
+static int w1_uart_serdev_open(struct w1_uart_device *w1dev)
+{
+	struct serdev_device *serdev = w1dev->serdev;
+	struct device *dev = &serdev->dev;
+	int ret;
+
+	ret = devm_serdev_device_open(dev, serdev);
+	if (ret < 0)
+		return ret;
+
+	ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
+	if (ret < 0) {
+		dev_err(dev, "set parity failed\n");
+		return ret;
+	}
+
+	ret = w1_uart_set_config_reset(w1dev);
+	if (ret < 0) {
+		dev_err(dev, "config for reset failed\n");
+		return ret;
+	}
+
+	ret = w1_uart_set_config_touch_0(w1dev);
+	if (ret < 0) {
+		dev_err(dev, "config for touch-0 failed\n");
+		return ret;
+	}
+
+	ret = w1_uart_set_config_touch_1(w1dev);
+	if (ret < 0) {
+		dev_err(dev, "config for touch-1 failed\n");
+		return ret;
+	}
+
+	serdev_device_set_flow_control(serdev, false);
+
+	return 0;
+}
+
+/*
+ * Send one byte (tx_byte) and read one byte (rx_byte) via serdev.
+ */
+static int w1_uart_serdev_tx_rx(struct w1_uart_device *w1dev,
+				const struct w1_uart_config *w1cfg,
+				unsigned char *rx_byte)
+{
+	struct serdev_device *serdev = w1dev->serdev;
+	int ret;
+
+	serdev_device_write_flush(serdev);
+	serdev_device_set_baudrate(serdev, w1cfg->baudrate);
+
+	/* write and immediately read one byte */
+	reinit_completion(&w1dev->rx_byte_received);
+	ret = serdev_device_write_buf(serdev, &w1cfg->tx_byte, 1);
+	if (ret != 1)
+		return -EIO;
+	ret = wait_for_completion_interruptible_timeout(
+		&w1dev->rx_byte_received, W1_UART_TIMEOUT);
+	if (ret <= 0)
+		return -EIO;
+
+	/* locking could fail during driver remove or when serdev is
+	 * unexpectedly in the receive callback.
+	 */
+	if (!mutex_trylock(&w1dev->mutex))
+		return -EIO;
+
+	ret = w1dev->rx_err;
+	if (ret == 0)
+		*rx_byte = w1dev->rx_byte;
+
+	if (w1cfg->delay_us > 0)
+		fsleep(w1cfg->delay_us);
+
+	mutex_unlock(&w1dev->mutex);
+
+	return ret;
+}
+
+static int w1_uart_serdev_receive_buf(struct serdev_device *serdev,
+				      const unsigned char *buf, size_t count)
+{
+	struct w1_uart_device *w1dev = serdev_device_get_drvdata(serdev);
+
+	mutex_lock(&w1dev->mutex);
+
+	/* sent a single byte and receive one single byte */
+	if (count == 1) {
+		w1dev->rx_byte = buf[0];
+		w1dev->rx_err = 0;
+	} else {
+		w1dev->rx_err = -EIO;
+	}
+
+	mutex_unlock(&w1dev->mutex);
+	complete(&w1dev->rx_byte_received);
+
+	return count;
+}
+
+static const struct serdev_device_ops w1_uart_serdev_ops = {
+	.receive_buf = w1_uart_serdev_receive_buf,
+	.write_wakeup = serdev_device_write_wakeup,
+};
+
+/*
+ * 1-wire reset and presence detect: A present slave will manipulate
+ * the received byte by pulling the 1-Wire low.
+ */
+static u8 w1_uart_reset_bus(void *data)
+{
+	struct w1_uart_device *w1dev = data;
+	const struct w1_uart_config *w1cfg = &w1dev->cfg_reset;
+	unsigned char val;
+	int ret;
+
+	ret = w1_uart_serdev_tx_rx(w1dev, w1cfg, &val);
+	if (ret < 0)
+		return -1;
+
+	/* Device present (0) or no device (1) */
+	return val != w1cfg->tx_byte ? 0 : 1;
+}
+
+/*
+ * 1-Wire read and write cycle: Only the read-0 manipulates the
+ * received byte, all others left the line untouched.
+ */
+static u8 w1_uart_touch_bit(void *data, u8 bit)
+{
+	struct w1_uart_device *w1dev = data;
+	const struct w1_uart_config *w1cfg = bit ? &w1dev->cfg_touch_1 :
+						   &w1dev->cfg_touch_0;
+	unsigned char val;
+	int ret;
+
+	ret = w1_uart_serdev_tx_rx(w1dev, w1cfg, &val);
+
+	/* return inactive bus state on error */
+	if (ret < 0)
+		return 1;
+
+	return val == w1cfg->tx_byte ? 1 : 0;
+}
+
+static int w1_uart_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct w1_uart_device *w1dev;
+	int ret;
+
+	w1dev = devm_kzalloc(dev, sizeof(*w1dev), GFP_KERNEL);
+	if (!w1dev)
+		return -ENOMEM;
+	w1dev->bus.data = w1dev;
+	w1dev->bus.reset_bus = w1_uart_reset_bus;
+	w1dev->bus.touch_bit = w1_uart_touch_bit;
+	w1dev->serdev = serdev;
+
+	init_completion(&w1dev->rx_byte_received);
+	mutex_init(&w1dev->mutex);
+
+	ret = w1_uart_serdev_open(w1dev);
+	if (ret < 0)
+		return ret;
+	serdev_device_set_drvdata(serdev, w1dev);
+	serdev_device_set_client_ops(serdev, &w1_uart_serdev_ops);
+
+	return w1_add_master_device(&w1dev->bus);
+}
+
+static void w1_uart_remove(struct serdev_device *serdev)
+{
+	struct w1_uart_device *w1dev = serdev_device_get_drvdata(serdev);
+
+	mutex_lock(&w1dev->mutex);
+
+	w1_remove_master_device(&w1dev->bus);
+
+	mutex_unlock(&w1dev->mutex);
+}
+
+static const struct of_device_id w1_uart_of_match[] = {
+	{ .compatible = "w1-uart" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, w1_uart_of_match);
+
+static struct serdev_device_driver w1_uart_driver = {
+	.driver	= {
+		.name		= "w1-uart",
+		.of_match_table = w1_uart_of_match,
+	},
+	.probe	= w1_uart_probe,
+	.remove	= w1_uart_remove,
+};
+
+module_serdev_device_driver(w1_uart_driver);
+
+MODULE_DESCRIPTION("UART w1 bus driver");
+MODULE_AUTHOR("Christoph Winklhofer <cj.winklhofer@gmail.com>");
+MODULE_LICENSE("GPL");

-- 
2.43.0

Re: [PATCH v4 3/3] w1: add UART w1 bus driver

[Jiri Slaby]

On 06. 01. 24, 17:02, Christoph Winklhofer via B4 Relay wrote:
> From: Christoph Winklhofer <cj.winklhofer@gmail.com>
> 
> Add a UART 1-Wire bus driver. The driver utilizes the UART interface via
> the Serial Device Bus to create the 1-Wire timing patterns. The driver
> was tested on a "Raspberry Pi 3B" with a DS18B20 and on a "Variscite
> DART-6UL" with a DS18S20 temperature sensor.
> 
> The 1-Wire timing pattern and the corresponding UART baud-rate with the
> interpretation of the transferred bytes are described 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.
...
> --- /dev/null
> +++ b/drivers/w1/masters/w1-uart.c
> @@ -0,0 +1,398 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * w1-uart - UART 1-Wire bus driver
> + *
> + * Uses the UART interface (via Serial Device Bus) to create the 1-Wire
> + * timing patterns. Implements the following 1-Wire master interface:
> + *
> + * - reset_bus: requests baud-rate 9600
> + *
> + * - touch_bit: requests baud-rate 115200
> + *
> + * Author: Christoph Winklhofer <cj.winklhofer@gmail.com>
> + */
> +
> +#include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/jiffies.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/serdev.h>
> +#include <linux/w1.h>
> +
> +#define W1_UART_TIMEOUT msecs_to_jiffies(500)
> +
> +/*
> + * struct w1_uart_config - configuration for 1-Wire operation
> + *
> + * @baudrate: baud-rate returned from serdev
> + * @delay_us: delay to complete a 1-Wire cycle (in us)
> + * @tx_byte: byte to generate 1-Wire timing pattern
> + */
> +struct w1_uart_config {
> +	unsigned int baudrate;
> +	unsigned int delay_us;
> +	unsigned char tx_byte;

If it is a "byte", it should be u8.

> +};
> +
> +struct w1_uart_device {
> +	struct serdev_device *serdev;
> +	struct w1_bus_master bus;
> +
> +	struct w1_uart_config cfg_reset;
> +	struct w1_uart_config cfg_touch_0;
> +	struct w1_uart_config cfg_touch_1;
> +
> +	struct completion rx_byte_received;
> +	unsigned char rx_byte;

The same here.

> +	int rx_err;
> +
> +	struct mutex mutex;
> +};
> +
> +/*
> + * struct w1_uart_limits - limits for 1-Wire operations
> + *
> + * @baudrate: Requested baud-rate to create 1-Wire timing pattern
> + * @bit_min_us: minimum time for a bit (in us)
> + * @bit_max_us: maximum time for a bit (in us)
> + * @sample_us: timespan to sample 1-Wire response
> + * @cycle_us: duration of the 1-Wire cycle
> + */
> +struct w1_uart_limits {
> +	unsigned int baudrate;
> +	unsigned int bit_min_us;
> +	unsigned int bit_max_us;
> +	unsigned int sample_us;
> +	unsigned int cycle_us;
> +};
> +
> +static inline unsigned int baud_to_bit_ns(unsigned int baud)
> +{
> +	return 1000000000 / baud;

NSEC_PER_SEC

> +}
> +
> +static inline unsigned int to_ns(unsigned int us)
> +{
> +	return us * 1000;

NSEC_PER_USEC

> +}
> +
> +/*
> + * Set baud-rate, delay and tx-byte to create a 1-Wire pulse and adapt
> + * the tx-byte according to the actual baud-rate.
> + *
> + * Reject when:
> + * - time for a bit outside min/max range
> + * - a 1-Wire response is not detectable for sent byte
> + */
> +static int w1_uart_set_config(struct serdev_device *serdev,
> +			      const struct w1_uart_limits *limits,
> +			      struct w1_uart_config *w1cfg)
> +{
> +	unsigned int bits_low;
> +	unsigned int bit_ns;
> +	unsigned int low_ns;
> +
> +	w1cfg->baudrate = serdev_device_set_baudrate(serdev, limits->baudrate);
> +	if (w1cfg->baudrate == 0)
> +		return -EINVAL;
> +
> +	/* Compute in nanoseconds for accuracy */
> +	bit_ns = baud_to_bit_ns(w1cfg->baudrate);
> +	bits_low = to_ns(limits->bit_min_us) / bit_ns;
> +	/* start bit is always low */
> +	low_ns = bit_ns * (bits_low + 1);
> +
> +	if (low_ns < to_ns(limits->bit_min_us))
> +		return -EINVAL;
> +
> +	if (low_ns > to_ns(limits->bit_max_us))
> +		return -EINVAL;
> +
> +	/* 1-Wire response detectable for sent byte */
> +	if (limits->sample_us > 0 &&
> +	    bit_ns * 8 < low_ns + to_ns(limits->sample_us))

BITS_PER_BYTE

> +		return -EINVAL;
> +
> +	/* delay to complete 1-Wire cycle, include start and stop-bit */
> +	w1cfg->delay_us = 0;
> +	if (bit_ns * 10 < to_ns(limits->cycle_us))

What is this 10? Dub it.

> +		w1cfg->delay_us =
> +			(to_ns(limits->cycle_us) - bit_ns * 10) / 1000;

And this 10?

The end: / NSEC_PER_USEC

> +
> +	/* byte to create 1-Wire pulse */
> +	w1cfg->tx_byte = 0xff << bits_low;
> +
> +	return 0;
> +}
...

> +static int w1_uart_serdev_tx_rx(struct w1_uart_device *w1dev,
> +				const struct w1_uart_config *w1cfg,
> +				unsigned char *rx_byte)

u8 *

> +{
...
> +}
> +
> +static int w1_uart_serdev_receive_buf(struct serdev_device *serdev,
> +				      const unsigned char *buf, size_t count)

serdev already uses u8 * here. You are basing on the top of some old tree.

regards,
-- 
js
suse labs

Re: [PATCH v4 3/3] w1: add UART w1 bus driver

[Christoph Winklhofer]

On Mon, Jan 08, 2024 at 07:18:31AM +0100, Jiri Slaby wrote:
> On 06. 01. 24, 17:02, Christoph Winklhofer via B4 Relay wrote:
> > From: Christoph Winklhofer <cj.winklhofer@gmail.com>
> > 
> > Add a UART 1-Wire bus driver. The driver utilizes the UART interface via
> > the Serial Device Bus to create the 1-Wire timing patterns. The driver
> > was tested on a "Raspberry Pi 3B" with a DS18B20 and on a "Variscite
> > DART-6UL" with a DS18S20 temperature sensor.
> > 
> > The 1-Wire timing pattern and the corresponding UART baud-rate with the
> > interpretation of the transferred bytes are described 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.
> ...
> > --- /dev/null
> > +++ b/drivers/w1/masters/w1-uart.c
> > @@ -0,0 +1,398 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
> > +/*
> > + * w1-uart - UART 1-Wire bus driver
> > + *
> > + * Uses the UART interface (via Serial Device Bus) to create the 1-Wire
> > + * timing patterns. Implements the following 1-Wire master interface:
> > + *
> > + * - reset_bus: requests baud-rate 9600
> > + *
> > + * - touch_bit: requests baud-rate 115200
> > + *
> > + * Author: Christoph Winklhofer <cj.winklhofer@gmail.com>
> > + */
> > +
> > +#include <linux/completion.h>
> > +#include <linux/delay.h>
> > +#include <linux/jiffies.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/of.h>
> > +#include <linux/serdev.h>
> > +#include <linux/w1.h>
> > +
> > +#define W1_UART_TIMEOUT msecs_to_jiffies(500)
> > +
> > +/*
> > + * struct w1_uart_config - configuration for 1-Wire operation
> > + *
> > + * @baudrate: baud-rate returned from serdev
> > + * @delay_us: delay to complete a 1-Wire cycle (in us)
> > + * @tx_byte: byte to generate 1-Wire timing pattern
> > + */
> > +struct w1_uart_config {
> > +	unsigned int baudrate;
> > +	unsigned int delay_us;
> > +	unsigned char tx_byte;
> 
> If it is a "byte", it should be u8.
> 
will change this and all others to u8.

...
> > +
> > +static inline unsigned int baud_to_bit_ns(unsigned int baud)
> > +{
> > +	return 1000000000 / baud;
> 
> NSEC_PER_SEC
> 
> > +}
> > +
> > +static inline unsigned int to_ns(unsigned int us)
> > +{
> > +	return us * 1000;
> 
> NSEC_PER_USEC
> 
and use the correct constants.

...
> > +}
> > +
> > +/*
> > + * Set baud-rate, delay and tx-byte to create a 1-Wire pulse and adapt
> > + * the tx-byte according to the actual baud-rate.
> > + *
> > + * Reject when:
> > + * - time for a bit outside min/max range
> > + * - a 1-Wire response is not detectable for sent byte
> > + */
> > +static int w1_uart_set_config(struct serdev_device *serdev,
> > +			      const struct w1_uart_limits *limits,
> > +			      struct w1_uart_config *w1cfg)
> > +{
...
> > +	/* 1-Wire response detectable for sent byte */
> > +	if (limits->sample_us > 0 &&
> > +	    bit_ns * 8 < low_ns + to_ns(limits->sample_us))
> 
> BITS_PER_BYTE
> 
ok, change it (it is the time for the UART data-frame).
> > +		return -EINVAL;
> > +
> > +	/* delay to complete 1-Wire cycle, include start and stop-bit */
> > +	w1cfg->delay_us = 0;
> > +	if (bit_ns * 10 < to_ns(limits->cycle_us))
> 
> What is this 10? Dub it.
> 
> > +		w1cfg->delay_us =
> > +			(to_ns(limits->cycle_us) - bit_ns * 10) / 1000;
> 
> And this 10?
> 
> The end: / NSEC_PER_USEC
> 
will be more explicit (it is the time for the UART packet:
BITS_PER_BYTE + 2 (start and stop-bit).

...
> > +static int w1_uart_serdev_receive_buf(struct serdev_device *serdev,
> > +				      const unsigned char *buf, size_t count)
> 
> serdev already uses u8 * here. You are basing on the top of some old tree.
Yes, this patch is based on the w1-next branch of
  git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux-w1.git
was not sure from where to start. I guess that this change is probably in
the w1-tree after the next stable release.
> 
> regards,
> -- 
> js
> suse labs
> 
Thanks Jiri for the review!

Kind regards,
Christoph

Re: [PATCH v4 3/3] w1: add UART w1 bus driver

[Krzysztof Kozlowski]

On 08/01/2024 19:03, Christoph Winklhofer wrote:
> ...
>>> +static int w1_uart_serdev_receive_buf(struct serdev_device *serdev,
>>> +				      const unsigned char *buf, size_t count)
>>
>> serdev already uses u8 * here. You are basing on the top of some old tree.

Old? Your change came for v6.8 and this was sent when all trees were
based on v6.7-rc1. What newer tree could have this been?

> Yes, this patch is based on the w1-next branch of
>   git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux-w1.git
> was not sure from where to start. I guess that this change is probably in
> the w1-tree after the next stable release.

That's a timing issue. For that particular case, where this was
targeting next-next cycle, you should have based this on linux-next. In
other cases this would require cross-tree merging due to dependencies
which none of us were aware, so no harm.


Best regards,
Krzysztof

Re: [PATCH v4 0/3] w1: add UART w1 bus driver

[Krzysztof Kozlowski]

On 06/01/2024 17:02, Christoph Winklhofer via B4 Relay wrote:
> 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 v4:
> - rework baud-rate configuration: also check max bit-time, support higher
>   baud-rates by adding a delay to complete 1-Wire cycle.
> - dt-binding w1-uart: specify baud-rates for 1-Wire operations
> - Link to v3: https://lore.kernel.org/r/20240105-w1-uart-v3-0-8687093b2e76@gmail.com
> 

You can slow down a bit. You sent v2 too late to be applied. Then you
sent v3 and next day v4.

While I like approach to release early, release often, it does not
necessarily apply to the bindings. Bindings should be complete, which
means they should describe the hardware as fully as possible.

About the driver, you can develop it incrementally, it is a good idea,
however since ~rc6 my w1 tree is closed. It will remain closed till next
rc1 is released (merge window finished). Nothing will get applied during
that time, so if you intend to add new features, better to send v5 after
the merge window (instead v4 now, v5 tomorrow, v6 next week and then v7
after rc1).

Best regards,
Krzysztof

Re: [PATCH v4 0/3] w1: add UART w1 bus driver

[Christoph Winklhofer]

On Sat, Jan 06, 2024 at 05:56:34PM +0100, Krzysztof Kozlowski wrote:
> On 06/01/2024 17:02, Christoph Winklhofer via B4 Relay wrote:
> > 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 v4:
> > - rework baud-rate configuration: also check max bit-time, support higher
> >   baud-rates by adding a delay to complete 1-Wire cycle.
> > - dt-binding w1-uart: specify baud-rates for 1-Wire operations
> > - Link to v3: https://lore.kernel.org/r/20240105-w1-uart-v3-0-8687093b2e76@gmail.com
> > 
> 
> You can slow down a bit. You sent v2 too late to be applied. Then you
> sent v3 and next day v4.
> 
> While I like approach to release early, release often, it does not
> necessarily apply to the bindings. Bindings should be complete, which
> means they should describe the hardware as fully as possible.
> 
> About the driver, you can develop it incrementally, it is a good idea,
> however since ~rc6 my w1 tree is closed. It will remain closed till next
> rc1 is released (merge window finished). Nothing will get applied during
> that time, so if you intend to add new features, better to send v5 after
> the merge window (instead v4 now, v5 tomorrow, v6 next week and then v7
> after rc1).
> 
> Best regards,
> Krzysztof
> 

Ok sorry, understood - thank you for the clarification.

Kind regards,
Christoph