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 minItems: 2 61 items: 62 - description: low-priority non-secure 63 - description: high-priority non-secure 64 - description: Secure 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 }; 106 107 firmware { 108 scpi { 109 compatible = "arm,scpi"; 110 mboxes = <&mhuA 1>; /* HP-NonSecure */ 111 shmem = <&cpu_scp_hpri>; /* HP-NonSecure */ 112 113 scpi_devpd: power-controller { 114 compatible = "arm,scpi-power-domains"; 115 num-domains = <2>; 116 #power-domain-cells = <1>; 117 }; 118 }; 119 }; 120 121 # Doorbell mode. 122 - | 123 soc { 124 #address-cells = <2>; 125 #size-cells = <2>; 126 127 mhuB: mailbox@2b2f0000 { 128 #mbox-cells = <2>; 129 compatible = "arm,mhu-doorbell", "arm,primecell"; 130 reg = <0 0x2b2f0000 0 0x1000>; 131 interrupts = <0 36 4>, /* LP-NonSecure */ 132 <0 35 4>, /* HP-NonSecure */ 133 <0 37 4>; /* Secure */ 134 clocks = <&clock 0 2 1>; 135 clock-names = "apb_pclk"; 136 }; 137 }; 138 139 firmware { 140 scmi { 141 compatible = "arm,scmi"; 142 mboxes = <&mhuB 0 0>, /* LP-NonSecure, 1st doorbell */ 143 <&mhuB 0 1>; /* LP-NonSecure, 2nd doorbell */ 144 mbox-names = "tx", "rx"; 145 shmem = <&cpu_scp_lpri0>, 146 <&cpu_scp_lpri1>; 147 148 #address-cells = <1>; 149 #size-cells = <0>; 150 151 scmi_devpd: protocol@11 { 152 reg = <0x11>; 153 #power-domain-cells = <1>; 154 }; 155 156 scmi_dvfs: protocol@13 { 157 reg = <0x13>; 158 #clock-cells = <1>; 159 160 mboxes = <&mhuB 1 2>, /* HP-NonSecure, 3rd doorbell */ 161 <&mhuB 1 3>; /* HP-NonSecure, 4th doorbell */ 162 mbox-names = "tx", "rx"; 163 shmem = <&cpu_scp_hpri0>, 164 <&cpu_scp_hpri1>; 165 }; 166 }; 167 }; 168 169... 170