1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/mailbox/arm,mhu.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: ARM MHU Mailbox Controller
8
9maintainers:
10  - Jassi Brar <jaswinder.singh@linaro.org>
11
12description: |
13  The ARM's Message-Handling-Unit (MHU) is a mailbox controller that has 3
14  independent channels/links to communicate with remote processor(s).  MHU links
15  are hardwired on a platform. A link raises interrupt for any received data.
16  However, there is no specified way of knowing if the sent data has been read
17  by the remote. This driver assumes the sender polls STAT register and the
18  remote clears it after having read the data.  The last channel is specified to
19  be a 'Secure' resource, hence can't be used by Linux running NS.
20
21  The MHU hardware also allows operations in doorbell mode. The MHU drives the
22  interrupt signal using a 32-bit register, with all 32-bits logically ORed
23  together. It provides a set of registers to enable software to set, clear and
24  check the status of each of the bits of this register independently. The use
25  of 32 bits per interrupt line enables software to provide more information
26  about the source of the interrupt. For example, each bit of the register can
27  be associated with a type of event that can contribute to raising the
28  interrupt. Each of the 32-bits can be used as "doorbell" to alert the remote
29  processor.
30
31# We need a select here so we don't match all nodes with 'arm,primecell'
32select:
33  properties:
34    compatible:
35      contains:
36        enum:
37          - arm,mhu
38          - arm,mhu-doorbell
39  required:
40    - compatible
41
42properties:
43  compatible:
44    oneOf:
45      - description: Data transfer mode
46        items:
47          - const: arm,mhu
48          - const: arm,primecell
49
50      - description: Doorbell mode
51        items:
52          - const: arm,mhu-doorbell
53          - const: arm,primecell
54
55
56  reg:
57    maxItems: 1
58
59  interrupts:
60    items:
61      - description: low-priority non-secure
62      - description: high-priority non-secure
63      - description: Secure
64    maxItems: 3
65
66  clocks:
67    maxItems: 1
68
69  clock-names:
70    items:
71      - const: apb_pclk
72
73  '#mbox-cells':
74    description: |
75      Set to 1 in data transfer mode and represents index of the channel.
76      Set to 2 in doorbell mode and represents index of the channel and doorbell
77      number.
78    enum: [ 1, 2 ]
79
80required:
81  - compatible
82  - reg
83  - interrupts
84  - '#mbox-cells'
85
86additionalProperties: false
87
88examples:
89  # Data transfer mode.
90  - |
91    soc {
92        #address-cells = <2>;
93        #size-cells = <2>;
94
95        mhuA: mailbox@2b1f0000 {
96            #mbox-cells = <1>;
97            compatible = "arm,mhu", "arm,primecell";
98            reg = <0 0x2b1f0000 0 0x1000>;
99            interrupts = <0 36 4>, /* LP-NonSecure */
100                         <0 35 4>, /* HP-NonSecure */
101                         <0 37 4>; /* Secure */
102            clocks = <&clock 0 2 1>;
103            clock-names = "apb_pclk";
104        };
105
106        mhu_client_scb: scb@2e000000 {
107            compatible = "fujitsu,mb86s70-scb-1.0";
108            reg = <0 0x2e000000 0 0x4000>;
109            mboxes = <&mhuA 1>; /* HP-NonSecure */
110        };
111    };
112
113  # Doorbell mode.
114  - |
115    soc {
116        #address-cells = <2>;
117        #size-cells = <2>;
118
119        mhuB: mailbox@2b2f0000 {
120            #mbox-cells = <2>;
121            compatible = "arm,mhu-doorbell", "arm,primecell";
122            reg = <0 0x2b2f0000 0 0x1000>;
123            interrupts = <0 36 4>, /* LP-NonSecure */
124                         <0 35 4>, /* HP-NonSecure */
125                         <0 37 4>; /* Secure */
126            clocks = <&clock 0 2 1>;
127            clock-names = "apb_pclk";
128        };
129
130        mhu_client_scpi: scpi@2f000000 {
131            compatible = "arm,scpi";
132            reg = <0 0x2f000000 0 0x200>;
133            mboxes = <&mhuB 1 4>; /* HP-NonSecure, 5th doorbell */
134        };
135    };
136