[PATCH 0/2] Add support for the PCF8574T I/O expander.

[PATCH 0/2] Add support for the PCF8574T I/O expander.

[Tóth János via B4 Relay]

This patch series adds the driver support and the documentation for the
PCF8574T I2C I/O expander.

Signed-off-by: Tóth János <gomba007@gmail.com>
---
Tóth János (2):
      drivers: gpio: Add support for PCF8574T.
      dt-bindings: gpio: Add support for PCF8574T.

 Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml | 1 +
 drivers/gpio/Kconfig                                    | 2 +-
 drivers/gpio/gpio-pcf857x.c                             | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)
---
base-commit: 0ad2507d5d93f39619fc42372c347d6006b64319
change-id: 20250217-gpio-pcf8574t-597b9196639a

Best regards,
-- 
Tóth János <gomba007@gmail.com>

[PATCH 1/2] drivers: gpio: Add support for PCF8574T.

[Tóth János via B4 Relay]

From: Tóth János <gomba007@gmail.com>

Add support for the PCF8574T 8-bit I2C I/O expander.

The driver is tested with:
	+ tools/lsgpio
	+ tools/gpio-hammer
	+ some LEDs

[1] https://www.nxp.com/docs/en/data-sheet/PCF8574_PCF8574A.pdf

Signed-off-by: Tóth János <gomba007@gmail.com>
---
 drivers/gpio/Kconfig        | 2 +-
 drivers/gpio/gpio-pcf857x.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 98b4d1633b25..d7cdc3cc1b00 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1193,7 +1193,7 @@ config GPIO_PCF857X
 	  Most of these parts are from NXP, though TI is a second source for
 	  some of them.  Compatible models include:
 
-	  8 bits:   pcf8574, pcf8574a, pca8574, pca8574a,
+	  8 bits:   pcf8574, pcf8574a, pcf8574t, pca8574, pca8574a,
 	            pca9670, pca9672, pca9674, pca9674a,
 	            max7328, max7329
 
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
index 7c57eaeb0afe..2464c527a4e8 100644
--- a/drivers/gpio/gpio-pcf857x.c
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -20,6 +20,7 @@
 static const struct i2c_device_id pcf857x_id[] = {
 	{ "pcf8574", 8 },
 	{ "pcf8574a", 8 },
+	{ "pcf8574t", 8 },
 	{ "pca8574", 8 },
 	{ "pca9670", 8 },
 	{ "pca9672", 8 },
@@ -38,6 +39,7 @@ MODULE_DEVICE_TABLE(i2c, pcf857x_id);
 static const struct of_device_id pcf857x_of_table[] = {
 	{ .compatible = "nxp,pcf8574", (void *)8 },
 	{ .compatible = "nxp,pcf8574a", (void *)8 },
+	{ .compatible = "nxp,pcf8574t", (void *)8 },
 	{ .compatible = "nxp,pca8574", (void *)8 },
 	{ .compatible = "nxp,pca9670", (void *)8 },
 	{ .compatible = "nxp,pca9672", (void *)8 },

-- 
2.34.1

[PATCH 2/2] dt-bindings: gpio: Add support for PCF8574T.

[Tóth János via B4 Relay]

From: Tóth János <gomba007@gmail.com>

Add the necessary documentation for PCF8574T.

Signed-off-by: Tóth János <gomba007@gmail.com>
---
 Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml b/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
index 3718103e966a..cbe4cf96e942 100644
--- a/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
+++ b/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
@@ -34,6 +34,7 @@ properties:
       - nxp,pca9675
       - nxp,pcf8574
       - nxp,pcf8574a
+      - nxp,pcf8574t
       - nxp,pcf8575
 
   reg:

-- 
2.34.1

Re: [PATCH 2/2] dt-bindings: gpio: Add support for PCF8574T.

[Laurent Pinchart]

Hi Tóth,

Thank you for the patch.

On Mon, Feb 17, 2025 at 02:07:52PM +0100, Tóth János via B4 Relay wrote:
> From: Tóth János <gomba007@gmail.com>
> 
> Add the necessary documentation for PCF8574T.
> 
> Signed-off-by: Tóth János <gomba007@gmail.com>
> ---
>  Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml b/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
> index 3718103e966a..cbe4cf96e942 100644
> --- a/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
> +++ b/Documentation/devicetree/bindings/gpio/nxp,pcf8575.yaml
> @@ -34,6 +34,7 @@ properties:
>        - nxp,pca9675
>        - nxp,pcf8574
>        - nxp,pcf8574a
> +      - nxp,pcf8574t

Judging from patch 2/2, the PCF8574T is compatible with the PCF8574, the
only difference being the package. It makes no difference from a
software point of view. It seems you can simply use nxp,pcf8574 as a
compatible string in your device tree for the PCF8574T, and this patch
series isn't needed.

>        - nxp,pcf8575
>  
>    reg:

-- 
Regards,

Laurent Pinchart

Re: [PATCH 2/2] dt-bindings: gpio: Add support for PCF8574T.

[Tóth János]

Hi!

> Judging from patch 2/2, the PCF8574T is compatible with the PCF8574, the
> only difference being the package. It makes no difference from a
> software point of view. 

You are absolutely right. I simply thought that, since "PCF8574T" is written
on the chip, this patch would make it easier for the user to identify
the correct driver.

Regards,
Tóth János


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