dts: bindings: support both 15 and 22pins RaspberryPi CSI camera connector

Update the RaspberryPi CSI camera connector nexus gpio in order to only
expose the list of GPIO pins in order to support both 15 and 22pins
connectors as well as 15 to 22pins conversion cables.

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>

Author: Alain Volmat

dts/bindings/gpio/raspberrypi,csi-22pins-connector.yaml

@@ -0,0 +1,64 @@
+# Copyright 2025 STMicroelectronics
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  There are 2 variants of the Raspberry Pi CSI camera connector. Either 15pins
+  or 22pins. Here only GPIO provided by those connectors are abstracted since
+  others pins are directly connected to CSI PHY.
+  For reference, pinout of 15pins and 22pins connectors are references below.
+  In this gpio nexus, only GPIOs are represented and should be described in
+  the following way, allowing to have a single compatible for both 15pins
+  and 22pins connectors and also allowing to deal with 15 to 22 pins
+  conversion cables.
+
+  Nexus mapping:
+    1   IO0      pin 11 (15pins based) / pin 17 (22pins based)
+    2   IO1      pin 12 (15pins based) / pin 18 (22pins based)
+    3   I2C_SCL  pin 13 (15pins based) / pin 20 (22pins based)
+    4   I2C_SDA  pin 14 (15pins based) / pin 21 (22pins based)
+
+  For reference only, Raspberry 15pins Connector layout:
+    1   GND
+    2   CSI_D0_N
+    3   CSI_D0_P
+    4   GND
+    5   CSI_D1_N
+    6   CSI_D1_P
+    7   GND
+    8   CSI_CK_N
+    9   CSI_CK_P
+    10  GND
+    11  IO0
+    12  IO1
+    13  I2C_SCL
+    14  I2C_SDA
+    15  VCC (3v3)
+
+  For reference only, Raspberry 22pins Connector layout:
+
+    1	GND
+    2	CSI_D0_N
+    3	CSI_D0_P
+    4	GND
+    5	CSI_D1_N
+    6	CSI_D1_P
+    7	GND
+    8	CSI_CK_N
+    9	CSI_CK_P
+    10	GND
+    11	CSI_D2_N
+    12	CSI_D2_P
+    13	GND
+    14	CSI_D3_N
+    15	CSI_D3_P
+    16	GND
+    17	IO0
+    18	IO1
+    19	GND
+    20	I2C_SCL
+    21	I2C_SDA
+    22	VCC (3v3)
+
+compatible: "raspberrypi,csi-connector"
+
+include: [gpio-nexus.yaml, base.yaml]

dts/bindings/gpio/raspberrypi,csi-connector.yaml

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2025 STMicroelectronics
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef INCLUDE_ZEPHYR_DT_BINDINGS_GPIO_RASPBERRYPI_CSI_CONNECTOR_H_
+#define INCLUDE_ZEPHYR_DT_BINDINGS_GPIO_RASPBERRYPI_CSI_CONNECTOR_H_
+
+/**
+ * @name CSI camera connector GPIO list
+ * @{
+ */
+#define CSI_IO0	1	/**< GPIO0 */
+#define CSI_IO1	2	/**< GPIO1 */
+#define CSI_I2C_SCL	3	/**< I2C clock pin */
+#define CSI_I2C_SDA	4	/**< I2C data pin */
+/** @} */
+
+#endif /* INCLUDE_ZEPHYR_DT_BINDINGS_GPIO_RASPBERRYPI_CSI_CONNECTOR_H_ */