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Date: Mon, 15 Aug 2016 15:40:26 +0200
From: Peter Rosin <peda@...ntia.se>
To: <linux-kernel@...r.kernel.org>
CC: Peter Rosin <peda@...ntia.se>, Wolfram Sang <wsa@...-dreams.de>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Guenter Roeck <linux@...ck-us.net>,
"David S. Miller" <davem@...emloft.net>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
<linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
Crestez Dan Leonard <leonard.crestez@...el.com>
Subject: [PATCH v2 3/8] dt-bindings: i2c: add support for 'i2c-gate' subnode
Handle i2c gates similarly to how i2c arbitrators are handled.
This gets rid of a pointless 'reg' property for i2c gates.
I.e. this new and more compact style
some-gate {
i2c-gate {
#address-cells = <1>;
#size-cells = <0>;
some-i2c-device@50 {
reg = <0x50>;
};
};
};
instead of the old
some-gate {
#address-cells = <1>;
#size-cells = <0>;
i2c@0 {
reg = <0>;
#address-cells = <1>;
#size-cells = <0>;
some-i2c-device@50 {
reg = <0x50>;
};
};
};
Signed-off-by: Peter Rosin <peda@...ntia.se>
---
Documentation/devicetree/bindings/i2c/i2c-gate.txt | 41 ++++++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 42 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gate.txt
diff --git a/Documentation/devicetree/bindings/i2c/i2c-gate.txt b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
new file mode 100644
index 000000000000..0b057fb2a15a
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
@@ -0,0 +1,41 @@
+An i2c gate is useful to e.g. reduce the digital noise for RF tuners connected
+to the i2c bus. Gates are similar to arbitrators in that you need to perform
+some kind of operation to access the i2c bus past the arbitrator/gate, but
+there are no competing masters to consider for gates and therefore there is
+no arbitration happening for gates.
+
+Common i2c gate properties.
+
+- i2c-gate child node
+
+Required properties for the i2c-gate child node:
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties for i2c-gate child node:
+- Child nodes conforming to i2c bus binding
+
+
+Example :
+
+ /*
+ An Invensense mpu9150 at address 0x68 featuring an on-chip Asahi
+ Kasei ak8975 compass behind a gate.
+ */
+
+ mpu9150@68 {
+ compatible = "invensense,mpu9150";
+ reg = <0x68>;
+ interrupt-parent = <&gpio1>;
+ interrupts = <18 1>;
+
+ i2c-gate {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ ax8975@0c {
+ compatible = "ak,ak8975";
+ reg = <0x0c>;
+ };
+ };
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 1a61e2f5a0a9..7444b03a4c28 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5661,6 +5661,7 @@ F: Documentation/i2c/i2c-topology
F: Documentation/i2c/muxes/
F: Documentation/devicetree/bindings/i2c/i2c-mux*
F: Documentation/devicetree/bindings/i2c/i2c-arb*
+F: Documentation/devicetree/bindings/i2c/i2c-gate*
F: drivers/i2c/i2c-mux.c
F: drivers/i2c/muxes/
F: include/linux/i2c-mux.h
--
2.1.4
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