From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- .../devicetree/bindings/i2c/i2c-ocores.txt | 69 ++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-ocores.txt (limited to 'Documentation/devicetree/bindings/i2c/i2c-ocores.txt') diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt new file mode 100644 index 000000000..17bef9a34 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt @@ -0,0 +1,69 @@ +Device tree configuration for i2c-ocores + +Required properties: +- compatible : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst" +- reg : bus address start and address range size of device +- interrupts : interrupt number +- clocks : handle to the controller clock; see the note below. + Mutually exclusive with opencores,ip-clock-frequency +- opencores,ip-clock-frequency: frequency of the controller clock in Hz; + see the note below. Mutually exclusive with clocks +- #address-cells : should be <1> +- #size-cells : should be <0> + +Optional properties: +- clock-frequency : frequency of bus clock in Hz; see the note below. + Defaults to 100 KHz when the property is not specified +- reg-shift : device register offsets are shifted by this value +- reg-io-width : io register width in bytes (1, 2 or 4) +- regstep : deprecated, use reg-shift above + +Note +clock-frequency property is meant to control the bus frequency for i2c bus +drivers, but it was incorrectly used to specify i2c controller input clock +frequency. So the following rules are set to fix this situation: +- if clock-frequency is present and neither opencores,ip-clock-frequency nor + clocks are, then clock-frequency specifies i2c controller clock frequency. + This is to keep backwards compatibility with setups using old DTB. i2c bus + frequency is fixed at 100 KHz. +- if clocks is present it specifies i2c controller clock. clock-frequency + property specifies i2c bus frequency. +- if opencores,ip-clock-frequency is present it specifies i2c controller + clock frequency. clock-frequency property specifies i2c bus frequency. + +Examples: + + i2c0: ocores@a0000000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "opencores,i2c-ocores"; + reg = <0xa0000000 0x8>; + interrupts = <10>; + opencores,ip-clock-frequency = <20000000>; + + reg-shift = <0>; /* 8 bit registers */ + reg-io-width = <1>; /* 8 bit read/write */ + + dummy@60 { + compatible = "dummy"; + reg = <0x60>; + }; + }; +or + i2c0: ocores@a0000000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "opencores,i2c-ocores"; + reg = <0xa0000000 0x8>; + interrupts = <10>; + clocks = <&osc>; + clock-frequency = <400000>; /* i2c bus frequency 400 KHz */ + + reg-shift = <0>; /* 8 bit registers */ + reg-io-width = <1>; /* 8 bit read/write */ + + dummy@60 { + compatible = "dummy"; + reg = <0x60>; + }; + }; -- cgit v1.2.3-54-g00ecf