linux-kernel - [RFC PATCH v4 03/12] dt-bindings: media: Add bindings for bcm2835-unicam

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Message-Id: <20220203175009.558868-4-jeanmichel.hautbois@ideasonboard.com>
Date:   Thu,  3 Feb 2022 18:50:00 +0100
From:   Jean-Michel Hautbois <jeanmichel.hautbois@...asonboard.com>
To:     jeanmichel.hautbois@...asonboard.com
Cc:     dave.stevenson@...pberrypi.com, devicetree@...r.kernel.org,
        kernel-list@...pberrypi.com, laurent.pinchart@...asonboard.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
        lukasz@...y.st, mchehab@...nel.org, naush@...pberrypi.com,
        robh@...nel.org, tomi.valkeinen@...asonboard.com,
        nsaenz@...nel.org, bcm-kernel-feedback-list@...adcom.com
Subject: [RFC PATCH v4 03/12] dt-bindings: media: Add bindings for bcm2835-unicam

Introduce the dt-bindings documentation for bcm2835 CCP2/CSI2 Unicam
camera interface. Also add a MAINTAINERS entry for it.

Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
Signed-off-by: Naushir Patuck <naush@...pberrypi.com>
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@...asonboard.com>

---
v4:
- make MAINTAINERS its own patch
- describe the reg and clocks correctly
- use a vendor entry for the number of data lanes
---
 .../bindings/media/brcm,bcm2835-unicam.yaml   | 110 ++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml

diff --git a/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
new file mode 100644
index 000000000000..0725a0267c60
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/brcm,bcm2835-unicam.yaml
@@ -0,0 +1,110 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/media/brcm,bcm2835-unicam.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom BCM283x Camera Interface (Unicam)
+
+maintainers:
+  - Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>
+
+description: |-
+  The Unicam block on BCM283x SoCs is the receiver for either
+  CSI-2 or CCP2 data from image sensors or similar devices.
+
+  The main platform using this SoC is the Raspberry Pi family of boards.
+  On the Pi the VideoCore firmware can also control this hardware block,
+  and driving it from two different processors will cause issues.
+  To avoid this, the firmware checks the device tree configuration
+  during boot. If it finds device tree nodes starting by csi then
+  it will stop the firmware accessing the block, and it can then
+  safely be used via the device tree binding.
+
+properties:
+  compatible:
+    const: brcm,bcm2835-unicam
+
+  reg:
+    items:
+      - description: Unicam block.
+      - description: Clock Manager Image (CMI) block.
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Clock to drive the LP state machine of Unicam.
+      - description: Clock for the vpu (core clock).
+
+  clock-names:
+    items:
+      - const: lp
+      - const: vpu
+
+  power-domains:
+    items:
+      - description: Unicam power domain
+
+  brcm,num-data-lanes:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [ 2, 4 ]
+    description: Number of data lanes on the csi bus
+
+  port:
+    additionalProperties: false
+    $ref: /schemas/graph.yaml#/$defs/port-base
+
+    properties:
+      endpoint:
+        $ref: /schemas/media/video-interfaces.yaml#
+        unevaluatedProperties: false
+
+        properties:
+          data-lanes: true
+          link-frequencies: true
+
+        required:
+          - data-lanes
+          - link-frequencies
+
+    required:
+      - endpoint
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+  - power-domains
+  - brcm,num-data-lanes
+  - port
+
+additionalProperties: False
+
+examples:
+  - |
+    #include <dt-bindings/clock/bcm2835.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/power/raspberrypi-power.h>
+    csi1: csi@...01000 {
+        compatible = "brcm,bcm2835-unicam";
+        reg = <0x7e801000 0x800>,
+              <0x7e802004 0x4>;
+        interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&clocks BCM2835_CLOCK_CAM1>,
+                 <&firmware_clocks 4>;
+        clock-names = "lp", "vpu";
+        power-domains = <&power RPI_POWER_DOMAIN_UNICAM1>;
+        brcm,num-data-lanes = <2>;
+        port {
+                csi1_ep: endpoint {
+                        remote-endpoint = <&imx219_0>;
+                        data-lanes = <1 2>;
+                        link-frequencies = /bits/ 64 <456000000>;
+                };
+        };
+    };
+...
-- 
2.32.0