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From: Heiner Kallweit <hkallweit1@gmail.com>
To: Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Wolfram Sang <wsa@kernel.org>, Peter Rosin <peda@axentia.se>
Cc: "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: [PATCH v4 1/3] dt-bindings: i2c-gpio: Add properties for dealing with write-only SDA/SCL w/o pullup
Date: Tue, 17 Jan 2023 21:36:05 +0100	[thread overview]
Message-ID: <fa28a480-1980-16dd-0263-ae4866e7c7cc@gmail.com> (raw)
In-Reply-To: <57666b4f-4c12-7feb-caf1-5bd38908bfc7@gmail.com>

There are slave devices that understand I2C but have read-only SDA and
SCL. Examples are FD650 7-segment LED controller and its derivatives.
Typical board designs don't even have a pull-up for both pins.
Therefore add properties for not using open-drain. For write-only SCL
we have a property already, add one for write-only SDA.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v4:
- add no-pullup properties
---
 .../devicetree/bindings/i2c/i2c-gpio.yaml        | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-gpio.yaml b/Documentation/devicetree/bindings/i2c/i2c-gpio.yaml
index e0d76d5eb..67898cc52 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-gpio.yaml
+++ b/Documentation/devicetree/bindings/i2c/i2c-gpio.yaml
@@ -33,6 +33,10 @@ properties:
       open drain.
     maxItems: 1
 
+  i2c-gpio,sda-output-only:
+    description: sda as output only
+    type: boolean
+
   i2c-gpio,scl-output-only:
     description: scl as output only
     type: boolean
@@ -63,6 +67,18 @@ properties:
       GPIO line used for SCL into open drain mode, and that something is not
       the GPIO chip. It is essentially an inconsistency flag.
 
+  i2c-gpio,sda-has-no-pullup:
+    type: boolean
+    description: sda is used in a non-compliant way and has no pull-up.
+      Therefore disable open-drain. This property is mutually-exclusive
+      with i2c-gpio,sda-open-drain.
+
+  i2c-gpio,scl-has-no-pullup:
+    type: boolean
+    description: scl is used in a non-compliant way and has no pull-up.
+      Therefore disable open-drain. This property is mutually-exclusive
+      with i2c-gpio,scl-open-drain.
+
 required:
   - compatible
   - sda-gpios
-- 
2.39.0



  reply	other threads:[~2023-01-17 22:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-17 20:34 [PATCH v4 0/3] i2c: gpio: support write-only sda Heiner Kallweit
2023-01-17 20:36 ` Heiner Kallweit [this message]
2023-01-18 16:32   ` [PATCH v4 1/3] dt-bindings: i2c-gpio: Add properties for dealing with write-only SDA/SCL w/o pullup Rob Herring
2023-01-18 17:55     ` Heiner Kallweit
2023-01-17 20:38 ` [PATCH v4 2/3] i2c: algo: bit: allow getsda to be NULL Heiner Kallweit
2023-01-17 20:39 ` [PATCH v4 3/3] i2c: gpio: support write-only sda/scl w/o pull-up Heiner Kallweit

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