linux-kernel - [PATCH 1/4] mailbox: arm_mhuv2: add device tree binding documentation

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Date:   Wed, 17 Jul 2019 20:26:13 +0100
From:   Tushar Khandelwal <tushar.khandelwal@....com>
To:     linux-kernel@...r.kernel.org
Cc:     tushar.2nov@...il.com, morten_bp@...e.dk, jassisinghbrar@...il.com,
        nd@....com, Morten Borup Petersen <morten.petersen@....com>,
        Tushar Khandelwal <tushar.khandelwal@....com>,
        robh+dt@...nel.org, mark.rutland@....com,
        devicetree@...r.kernel.org
Subject: [PATCH 1/4] mailbox: arm_mhuv2: add device tree binding documentation

From: Morten Borup Petersen <morten.petersen@....com>

This patch adds device tree binding for Message Handling Unit
controller version 2 from Arm.

Signed-off-by: Morten Borup Petersen <morten.petersen@....com>
Signed-off-by: Tushar Khandelwal <tushar.khandelwal@....com>
Cc: robh+dt@...nel.org
Cc: mark.rutland@....com
Cc: devicetree@...r.kernel.org
Cc: jassisinghbrar@...il.com
---
 .../devicetree/bindings/mailbox/arm,mhuv2.txt | 108 ++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mailbox/arm,mhuv2.txt

diff --git a/Documentation/devicetree/bindings/mailbox/arm,mhuv2.txt b/Documentation/devicetree/bindings/mailbox/arm,mhuv2.txt
new file mode 100644
index 000000000000..3a05593414bc
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/arm,mhuv2.txt
@@ -0,0 +1,108 @@
+Arm MHUv2 Mailbox Driver
+========================
+
+The Arm Message-Handling-Unit (MHU) Version 2 is a mailbox controller that has
+between 1 and 124 channel windows to provide unidirectional communication with
+remote processor(s).
+
+Given the unidirectional nature of the device, an MHUv2 mailbox may only be
+written to or read from. If a pair of MHU devices is implemented between two
+processing elements to provide bidirectional communication, these must be
+specified as two separate mailboxes.
+
+A device tree node for an Arm MHUv2 device must specify either a receiver frame
+or a sender frame, indicating which end of the unidirectional MHU device which
+the device node entry describes.
+
+An MHU device must be specified with a transport protocol. The transport
+protocol of an MHU device determines the method of data transmission as well as
+the number of provided mailboxes.
+Following are the possible transport protocol types:
+- Single-word:	An MHU device implements as many mailboxes as it
+		provides channel windows. Data is transmitted through
+		the MHU registers.
+- Multi-word:	An MHU device implements a single mailbox. All channel windows
+		will be used during transmission. Data is transmitted through
+		the MHU registers.
+- Doorbell:	An MHU device implements as many mailboxes as there are flag
+		bits available in its channel windows. Optionally, data may
+		be transmitted through a shared memory region, wherein the MHU
+		is used strictly as an interrupt generation mechanism.
+
+Mailbox Device Node:
+====================
+
+Required properties:
+--------------------
+- compatible:	Shall be "arm,mhuv2" & "arm,primecell"
+- reg:		Contains the mailbox register address range (base
+		address and length)
+- #mbox-cells	Shall be 1 - the index of the channel needed.
+- mhu-frame	Frame type of the device.
+		Shall be either "sender" or "receiver"
+- mhu-protocol	Transport protocol of the device. Shall be one of the
+		following: "single-word", "multi-word", "doorbell"
+
+Required properties (receiver frame):
+-------------------------------------
+- interrupts:	Contains the interrupt information corresponding to the
+		combined interrupt of the receiver frame
+
+Example:
+--------
+
+	mbox_mw_tx: mhu@...00000 {
+		compatible = "arm,mhuv2","arm,primecell";
+		reg = <0x10000000 0x1000>;
+		clocks = <&refclk100mhz>;
+		clock-names = "apb_pclk";
+		#mbox-cells = <1>;
+		mhu-protocol = "multi-word";
+		mhu-frame = "sender";
+	};
+
+	mbox_sw_tx: mhu@...00000 {
+		compatible = "arm,mhuv2","arm,primecell";
+		reg = <0x11000000 0x1000>;
+		clocks = <&refclk100mhz>;
+		clock-names = "apb_pclk";
+		#mbox-cells = <1>;
+		mhu-protocol = "single-word";
+		mhu-frame = "sender";
+	};
+
+	mbox_db_rx: mhu@...00000 {
+		compatible = "arm,mhuv2","arm,primecell";
+		reg = <0x12000000 0x1000>;
+		clocks = <&refclk100mhz>;
+		clock-names = "apb_pclk";
+		#mbox-cells = <1>;
+		interrupts = <0 45 4>;
+		interrupt-names = "mhu_rx";
+		mhu-protocol = "doorbell";
+		mhu-frame = "receiver";
+	};
+
+	mhu_client: scb@...00000 {
+	compatible = "fujitsu,mb86s70-scb-1.0";
+	reg = <0 0x2e000000 0x4000>;
+	mboxes =
+		// For multi-word frames, client may only instantiate a single
+		// mailbox for a mailbox controller
+		<&mbox_mw_tx 0>,
+
+		// For single-word frames, client may instantiate as many
+		// mailboxes as there are channel windows in the MHU
+		 <&mbox_sw_tx 0>,
+		 <&mbox_sw_tx 1>,
+		 <&mbox_sw_tx 2>,
+		 <&mbox_sw_tx 3>,
+
+		// For doorbell frames, client may instantiate as many mailboxes
+		// as there are bits available in the combined number of channel
+		// windows ((channel windows * 32) mailboxes)
+		 <mbox_db_rx 0>,
+		 <mbox_db_rx 1>,
+		 ...
+		 <mbox_db_rx 17>;
+	};
\ No newline at end of file
-- 
2.17.1