dt-bindings: mailbox: Add devicetree binding for Qcom IPCC

Add devicetree YAML binding for Qualcomm Inter-Processor Communication
Controller (IPCC) block.
Reviewed-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NJassi Brar <jaswinder.singh@linaro.org>

Documentation/devicetree/bindings/mailbox/qcom-ipcc.yaml

+# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/qcom-ipcc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Technologies, Inc. Inter-Processor Communication Controller
+
+maintainers:
+  - Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+
+description:
+  The Inter-Processor Communication Controller (IPCC) is a centralized hardware
+  to route interrupts across various subsystems. It involves a three-level
+  addressing scheme called protocol, client and signal. For example, consider an
+  entity on the Application Processor Subsystem (APSS) that wants to listen to
+  Modem's interrupts via Shared Memory Point to Point (SMP2P) interface. In such
+  a case, the client would be Modem (client-id is 2) and the signal would be
+  SMP2P (signal-id is 2). The SMP2P itself falls under the Multiprocessor (MPROC)
+  protocol (protocol-id is 0). Refer include/dt-bindings/mailbox/qcom-ipcc.h
+  for the list of such IDs.
+
+properties:
+  compatible:
+    items:
+      - enum:
+        - qcom,sm8250-ipcc
+      - const: qcom,ipcc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  interrupt-controller: true
+
+  "#interrupt-cells":
+    const: 3
+    description:
+      The first cell is the client-id, the second cell is the signal-id and the
+      third cell is the interrupt type.
+
+  "#mbox-cells":
+    const: 2
+    description:
+      The first cell is the client-id, and the second cell is the signal-id.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - interrupt-controller
+  - "#interrupt-cells"
+  - "#mbox-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+        #include <dt-bindings/interrupt-controller/arm-gic.h>
+        #include <dt-bindings/mailbox/qcom-ipcc.h>
+
+        mailbox@408000 {
+                compatible = "qcom,sm8250-ipcc", "qcom,ipcc";
+                reg = <0x408000 0x1000>;
+                interrupts = <GIC_SPI 229 IRQ_TYPE_LEVEL_HIGH>;
+                interrupt-controller;
+                #interrupt-cells = <3>;
+                #mbox-cells = <2>;
+        };
+
+        smp2p-modem {
+                compatible = "qcom,smp2p";
+                interrupts-extended = <&ipcc_mproc IPCC_CLIENT_MPSS
+                                IPCC_MPROC_SIGNAL_SMP2P IRQ_TYPE_EDGE_RISING>;
+                mboxes = <&ipcc_mproc IPCC_CLIENT_MPSS IPCC_MPROC_SIGNAL_SMP2P>;
+
+                /* Other SMP2P fields */
+        };

include/dt-bindings/mailbox/qcom-ipcc.h

+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef __DT_BINDINGS_MAILBOX_IPCC_H
+#define __DT_BINDINGS_MAILBOX_IPCC_H
+
+/* Signal IDs for MPROC protocol */
+#define IPCC_MPROC_SIGNAL_GLINK_QMP	0
+#define IPCC_MPROC_SIGNAL_SMP2P		2
+#define IPCC_MPROC_SIGNAL_PING		3
+
+/* Client IDs */
+#define IPCC_CLIENT_AOP			0
+#define IPCC_CLIENT_TZ			1
+#define IPCC_CLIENT_MPSS		2
+#define IPCC_CLIENT_LPASS		3
+#define IPCC_CLIENT_SLPI		4
+#define IPCC_CLIENT_SDC			5
+#define IPCC_CLIENT_CDSP		6
+#define IPCC_CLIENT_NPU			7
+#define IPCC_CLIENT_APSS		8
+#define IPCC_CLIENT_GPU			9
+#define IPCC_CLIENT_CVP			10
+#define IPCC_CLIENT_CAM			11
+#define IPCC_CLIENT_VPU			12
+#define IPCC_CLIENT_PCIE0		13
+#define IPCC_CLIENT_PCIE1		14
+#define IPCC_CLIENT_PCIE2		15
+#define IPCC_CLIENT_SPSS		16
+
+#endif