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Date:   Tue, 12 Mar 2019 09:30:51 -0700
Message-Id: <20190312163051.155405-1-venture@google.com>
Mime-Version: 1.0
Subject: [PATCH v7 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support
From:   Patrick Venture <venture@google.com>
To:     venture@google.com, robh+dt@kernel.org, mark.rutland@arm.com,
        joel@jms.id.au, andrew@aj.id.au, gregkh@linuxfoundation.org
Cc:     devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.

Signed-off-by: Patrick Venture <venture@google.com>
---
Changes for v7:
- Moved node under the syscon node it requires
Changes for v6:
- None
Changes for v5:
- None
Changes for v4:
- None
Changes for v3:
- None
Changes for v2:
- Added comment about syscon required parameter.
---
 .../bindings/misc/aspeed-p2a-ctrl.txt         | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt

diff --git a/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
new file mode 100644
index 000000000000..088cc4e3dc54
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
@@ -0,0 +1,48 @@
+======================================================================
+Device tree bindings for Aspeed AST2400/AST2500 PCI-to-AHB Bridge Control Driver
+======================================================================
+
+The bridge is available on platforms with the VGA enabled on the Aspeed device.
+In this case, the host has access to a 64KiB window into all of the BMC's
+memory.  The BMC can disable this bridge.  If the bridge is enabled, the host
+has read access to all the regions of memory, however the host only has read
+and write access depending on a register controlled by the BMC.
+
+Required properties:
+===================
+
+ - compatible: must be one of:
+	- "aspeed,ast2400-p2a-ctrl"
+	- "aspeed,ast2500-p2a-ctrl"
+
+ - syscon: handle to syscon device node controlling PCI.
+
+Optional properties:
+===================
+
+- memory-region: A phandle to a reserved_memory region to be used for the PCI
+		to AHB mapping
+
+The p2a-control node should be the child of a syscon node with the required
+property:
+
+- compatible : Should be one of the following:
+		"aspeed,ast2400-scu", "syscon", "simple-mfd"
+		"aspeed,g4-scu", "syscon", "simple-mfd"
+		"aspeed,ast2500-scu", "syscon", "simple-mfd"
+		"aspeed,g5-scu", "syscon", "simple-mfd"
+
+Example:
+
+g4 Example
+----------
+
+syscon: scu@1e6e2000 {
+	compatible = "aspeed,ast2400-scu", "syscon", "simple-mfd";
+	reg = <0x1e6e2000 0x1a8>;
+
+	p2a: p2a-control {
+		compatible = "aspeed,ast2400-p2a-ctrl";
+		memory-region = <&reserved_memory>;
+	};
+};
-- 
2.21.0.360.g471c308f928-goog