From: Max Filippov <jcmvbkbc@gmail.com>
Date: Mon, 2 Feb 2015 15:28:12 +0000 (+0300)
Subject: i2c: ocores: fix clock-frequency binding usage
X-Git-Tag: fixes-v4.0-rc1~32^2~8
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a33a85401ecdb0e2c01ea86d9e36a5711ce01d4;p=pandora-kernel.git

i2c: ocores: fix clock-frequency binding usage

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.
Introduce new attribute, opencores,ip-clock-frequency, that specifies i2c
controller clock frequency and make clock-frequency attribute compatible
with other i2c drivers. Maintain backwards compatibility in case
opencores,ip-clock-frequency attribute is missing.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
---

diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
index 1637c298a1b3..5bef3adf2c35 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
@@ -4,15 +4,29 @@ 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
+- opencores,ip-clock-frequency: frequency of the controller clock in Hz;
+                    see the note below
 - #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 opencores,ip-clock-frequency is not,
+  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 opencores,ip-clock-frequency is present it specifies i2c controller
+  clock frequency. clock-frequency property specifies i2c bus frequency.
+
 Example:
 
 	i2c0: ocores@a0000000 {
@@ -21,7 +35,7 @@ Example:
 		compatible = "opencores,i2c-ocores";
 		reg = <0xa0000000 0x8>;
 		interrupts = <10>;
-		clock-frequency = <20000000>;
+		opencores,ip-clock-frequency = <20000000>;
 
 		reg-shift = <0>;	/* 8 bit registers */
 		reg-io-width = <1>;	/* 8 bit read/write */
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