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# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/mailbox/arm,mhu.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: ARM MHU Mailbox Controller
maintainers:
- Jassi Brar <jaswinder.singh@linaro.org>
description: |
The ARM's Message-Handling-Unit (MHU) is a mailbox controller that has 3
independent channels/links to communicate with remote processor(s). MHU links
are hardwired on a platform. A link raises interrupt for any received data.
However, there is no specified way of knowing if the sent data has been read
by the remote. This driver assumes the sender polls STAT register and the
remote clears it after having read the data. The last channel is specified to
be a 'Secure' resource, hence can't be used by Linux running NS.
The MHU hardware also allows operations in doorbell mode. The MHU drives the
interrupt signal using a 32-bit register, with all 32-bits logically ORed
together. It provides a set of registers to enable software to set, clear and
check the status of each of the bits of this register independently. The use
of 32 bits per interrupt line enables software to provide more information
about the source of the interrupt. For example, each bit of the register can
be associated with a type of event that can contribute to raising the
interrupt. Each of the 32-bits can be used as "doorbell" to alert the remote
processor.
# We need a select here so we don't match all nodes with 'arm,primecell'
select:
properties:
compatible:
contains:
enum:
- arm,mhu
- arm,mhu-doorbell
required:
- compatible
properties:
compatible:
oneOf:
- description: Data transfer mode
items:
- const: arm,mhu
- const: arm,primecell
- description: Doorbell mode
items:
- const: arm,mhu-doorbell
- const: arm,primecell
reg:
maxItems: 1
interrupts:
items:
- description: low-priority non-secure
- description: high-priority non-secure
- description: Secure
clocks:
maxItems: 1
clock-names:
items:
- const: apb_pclk
'#mbox-cells':
description: |
Set to 1 in data transfer mode and represents index of the channel.
Set to 2 in doorbell mode and represents index of the channel and doorbell
number.
enum: [ 1, 2 ]
required:
- compatible
- reg
- interrupts
- '#mbox-cells'
additionalProperties: false
examples:
# Data transfer mode.
- |
soc {
#address-cells = <2>;
#size-cells = <2>;
mhuA: mailbox@2b1f0000 {
#mbox-cells = <1>;
compatible = "arm,mhu", "arm,primecell";
reg = <0 0x2b1f0000 0 0x1000>;
interrupts = <0 36 4>, /* LP-NonSecure */
<0 35 4>, /* HP-NonSecure */
<0 37 4>; /* Secure */
clocks = <&clock 0 2 1>;
clock-names = "apb_pclk";
};
mhu_client_scb: scb@2e000000 {
compatible = "fujitsu,mb86s70-scb-1.0";
reg = <0 0x2e000000 0 0x4000>;
mboxes = <&mhuA 1>; /* HP-NonSecure */
};
};
# Doorbell mode.
- |
soc {
#address-cells = <2>;
#size-cells = <2>;
mhuB: mailbox@2b2f0000 {
#mbox-cells = <2>;
compatible = "arm,mhu-doorbell", "arm,primecell";
reg = <0 0x2b2f0000 0 0x1000>;
interrupts = <0 36 4>, /* LP-NonSecure */
<0 35 4>, /* HP-NonSecure */
<0 37 4>; /* Secure */
clocks = <&clock 0 2 1>;
clock-names = "apb_pclk";
};
mhu_client_scpi: scpi@2f000000 {
compatible = "arm,scpi";
reg = <0 0x2f000000 0 0x200>;
mboxes = <&mhuB 1 4>; /* HP-NonSecure, 5th doorbell */
};
};
|
