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 65 clocks: 66 maxItems: 1 67 68 clock-names: 69 items: 70 - const: apb_pclk 71 72 '#mbox-cells': 73 description: | 74 Set to 1 in data transfer mode and represents index of the channel. 75 Set to 2 in doorbell mode and represents index of the channel and doorbell 76 number. 77 enum: [ 1, 2 ] 78 79required: 80 - compatible 81 - reg 82 - interrupts 83 - '#mbox-cells' 84 85additionalProperties: false 86 87examples: 88 # Data transfer mode. 89 - | 90 soc { 91 #address-cells = <2>; 92 #size-cells = <2>; 93 94 mhuA: mailbox@2b1f0000 { 95 #mbox-cells = <1>; 96 compatible = "arm,mhu", "arm,primecell"; 97 reg = <0 0x2b1f0000 0 0x1000>; 98 interrupts = <0 36 4>, /* LP-NonSecure */ 99 <0 35 4>, /* HP-NonSecure */ 100 <0 37 4>; /* Secure */ 101 clocks = <&clock 0 2 1>; 102 clock-names = "apb_pclk"; 103 }; 104 }; 105 106 firmware { 107 scpi { 108 compatible = "arm,scpi"; 109 mboxes = <&mhuA 1>; /* HP-NonSecure */ 110 shmem = <&cpu_scp_hpri>; /* HP-NonSecure */ 111 112 scpi_devpd: power-controller { 113 compatible = "arm,scpi-power-domains"; 114 num-domains = <2>; 115 #power-domain-cells = <1>; 116 }; 117 }; 118 }; 119 120 # Doorbell mode. 121 - | 122 soc { 123 #address-cells = <2>; 124 #size-cells = <2>; 125 126 mhuB: mailbox@2b2f0000 { 127 #mbox-cells = <2>; 128 compatible = "arm,mhu-doorbell", "arm,primecell"; 129 reg = <0 0x2b2f0000 0 0x1000>; 130 interrupts = <0 36 4>, /* LP-NonSecure */ 131 <0 35 4>, /* HP-NonSecure */ 132 <0 37 4>; /* Secure */ 133 clocks = <&clock 0 2 1>; 134 clock-names = "apb_pclk"; 135 }; 136 }; 137 138 firmware { 139 scmi { 140 compatible = "arm,scmi"; 141 mboxes = <&mhuB 0 0>, /* LP-NonSecure, 1st doorbell */ 142 <&mhuB 0 1>; /* LP-NonSecure, 2nd doorbell */ 143 mbox-names = "tx", "rx"; 144 shmem = <&cpu_scp_lpri0>, 145 <&cpu_scp_lpri1>; 146 147 #address-cells = <1>; 148 #size-cells = <0>; 149 150 scmi_devpd: protocol@11 { 151 reg = <0x11>; 152 #power-domain-cells = <1>; 153 }; 154 155 scmi_dvfs: protocol@13 { 156 reg = <0x13>; 157 #clock-cells = <1>; 158 159 mboxes = <&mhuB 1 2>, /* HP-NonSecure, 3rd doorbell */ 160 <&mhuB 1 3>; /* HP-NonSecure, 4th doorbell */ 161 mbox-names = "tx", "rx"; 162 shmem = <&cpu_scp_hpri0>, 163 <&cpu_scp_hpri1>; 164 }; 165 }; 166 }; 167 168... 169