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-rw-r--r--dts/Bindings/i2c/i2c-ocores.txt42
1 files changed, 39 insertions, 3 deletions
diff --git a/dts/Bindings/i2c/i2c-ocores.txt b/dts/Bindings/i2c/i2c-ocores.txt
index 1637c298a1..17bef9a34e 100644
--- a/dts/Bindings/i2c/i2c-ocores.txt
+++ b/dts/Bindings/i2c/i2c-ocores.txt
@@ -4,24 +4,60 @@ Required properties:
- compatible : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
- reg : bus address start and address range size of device
- interrupts : interrupt number
-- clock-frequency : frequency of bus clock in Hz
+- 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
-Example:
+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>;
- clock-frequency = <20000000>;
+ clocks = <&osc>;
+ clock-frequency = <400000>; /* i2c bus frequency 400 KHz */
reg-shift = <0>; /* 8 bit registers */
reg-io-width = <1>; /* 8 bit read/write */