Add reset-gpios and reset-duration-us properties to the
marvell,mv64xxx-i2c binding. These can be used to describe hardware
where a common reset GPIO is connected to all downstream devices on and
I2C bus. This reset will be asserted then released before the downstream
devices on the bus are probed.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---

Notes:
    Changes in v4:
    - Add r-by from Krzysztof
    Changes in v3:
    - Rename reset-delay-us to reset-duration-us to better reflect its
      purpose
    - Add default: for reset-duration-us
    - Add description: for reset-gpios
    Changes in v2:
    - Update commit message
    - Add reset-delay-us property

 .../devicetree/bindings/i2c/marvell,mv64xxx-i2c.yaml   | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/marvell,mv64xxx-i2c.yaml b/Documentation/devicetree/bindings/i2c/marvell,mv64xxx-i2c.yaml
index 461d1c9ee3f7..ecf5b279cfa4 100644
--- a/Documentation/devicetree/bindings/i2c/marvell,mv64xxx-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/marvell,mv64xxx-i2c.yaml
@@ -70,6 +70,16 @@ properties:
   resets:
     maxItems: 1
 
+  reset-gpios:
+    description:
+      GPIO pin providing a common reset for all downstream devices. This GPIO
+      will be asserted then released before the downstream devices are probed.
+    maxItems: 1
+
+  reset-duration-us:
+    description: Reset duration in us.
+    default: 1
+
   dmas:
     items:
       - description: RX DMA Channel
-- 
2.42.0

> +  reset-gpios:
> +    description:
> +      GPIO pin providing a common reset for all downstream devices. This GPIO
> +      will be asserted then released before the downstream devices are probed.

How about renaming this to "bus-reset-gpios"?

Reason: When I read "reset-gpios", then I assume the device itself will
be reset. In this case, the Marvell I2C controller. Some I2C mux devices
and PCA9564 already use the property like I described.

(resend as plain text)


On 27/10/23 00:15, Wolfram Sang wrote:
>> +  reset-gpios:
>> +    description:
>> +      GPIO pin providing a common reset for all downstream devices. This GPIO
>> +      will be asserted then released before the downstream devices are probed.
> How about renaming this to "bus-reset-gpios"?
>
> Reason: When I read "reset-gpios", then I assume the device itself will
> be reset. In this case, the Marvell I2C controller. Some I2C mux devices
> and PCA9564 already use the property like I described.

I don't have an objection to "bus-reset-gpios" it would be trivial for 
me to spin a v5 with the naming changed if everyone is in agreement 
(given my timezone I might just send out a v5 with this change and then 
it can be argued whether to apply v4 or v5).

Hi Chris,

On Wed, Oct 25, 2023 at 11:30:31AM +1300, Chris Packham wrote:
> Add reset-gpios and reset-duration-us properties to the
> marvell,mv64xxx-i2c binding. These can be used to describe hardware
> where a common reset GPIO is connected to all downstream devices on and
> I2C bus. This reset will be asserted then released before the downstream
> devices on the bus are probed.
> 
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Acked-by: Andi Shyti <andi.shyti@kernel.org>

Thanks,
Andi