powerpc/CPM: Add i2c pins to dts and board setup

Initialize I2C pins on boards with CPM1/CPM2 controllers and document the
i2c bus in booting-without-of.

The boards don't have any I2C chips connected to the I2C bus, so unless
some external chips are connected to the boards, this code is just an
example of setting everything else up.

Signed-off-by: Jochen Friedrich <jochen@scram.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt
index b68684d39f96..f6394b509430 100644
--- a/Documentation/powerpc/booting-without-of.txt
+++ b/Documentation/powerpc/booting-without-of.txt
@@ -2160,6 +2160,48 @@ platforms are moved over to use the flattened-device-tree model.
                 };
         };
 
+   x) I2C
+
+   The I2C controller is expressed as a bus under the CPM node.
+
+   Properties:
+   - compatible : "fsl,cpm1-i2c", "fsl,cpm2-i2c"
+   - reg : On CPM2 devices, the second resource doesn't specify the I2C
+     Parameter RAM itself, but the I2C_BASE field of the CPM2 Parameter RAM
+     (typically 0x8afc 0x2).
+   - #address-cells : Should be one. The cell is the i2c device address with
+     the r/w bit set to zero.
+   - #size-cells : Should be zero.
+   - clock-frequency : Can be used to set the i2c clock frequency. If
+     unspecified, a default frequency of 60kHz is being used.
+   The following two properties are deprecated. They are only used by legacy
+   i2c drivers to find the bus to probe:
+   - linux,i2c-index : Can be used to hard code an i2c bus number. By default,
+     the bus number is dynamically assigned by the i2c core.
+   - linux,i2c-class : Can be used to override the i2c class. The class is used
+     by legacy i2c device drivers to find a bus in a specific context like
+     system management, video or sound. By default, I2C_CLASS_HWMON (1) is
+     being used. The definition of the classes can be found in
+     include/i2c/i2c.h
+
+   Example, based on mpc823:
+
+        i2c@860 {
+                compatible = "fsl,mpc823-i2c",
+                             "fsl,cpm1-i2c";
+                reg = <0x860 0x20 0x3c80 0x30>;
+                interrupts = <16>;
+                interrupt-parent = <&CPM_PIC>;
+                fsl,cpm-command = <0x10>;
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                rtc@68 {
+                        compatible = "dallas,ds1307";
+                        reg = <0x68>;
+                };
+        };
+
    m) Chipselect/Local Bus
 
    Properties: