dtc: Add support for variable sized elements

Elements of size 8, 16, 32, and 64 bits are supported.  The new
/bits/ syntax was selected so as to not pollute the reserved
keyword space with uint8/uint16/... type names.

With this patch the following property assignment:

    property = /bits/ 16 <0x1234 0x5678 0x0 0xffff>;

is equivalent to:

    property = <0x12345678 0x0000ffff>;

It is now also possible to directly specify a 64 bit literal in a
cell list, also known as an array using:

    property = /bits/ 64 <0xdeadbeef00000000>;

It is an error to attempt to store a literal into an element that is
too small to hold the literal, and the compiler will generate an
error when it detects this.  For instance:

    property = /bits/ 8 <256>;

Will fail to compile.  It is also an error to attempt to place a
reference in a non 32-bit element.

The documentation has been changed to reflect that the cell list
is now an array of elements that can be of sizes other than the
default 32-bit cell size.

The sized_cells test tests the creation and access of 8, 16, 32,
and 64-bit sized elements.  It also tests that the creation of two
properties, one with 16 bit elements and one with 32 bit elements
result in the same property contents.

Signed-off-by: Anton Staaf <robotboy@chromium.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 23 insertions, 11 deletions

diff --git a/Documentation/dts-format.txt b/Documentation/dts-format.txt
index eae8b76..41741df 100644
--- a/Documentation/dts-format.txt
+++ b/Documentation/dts-format.txt
@@ -29,18 +29,28 @@ except for properties with empty (zero length) value which have the
 form:
 	[label:] property-name;
 
-Property values may be defined as an array of 32-bit integer cells, as
-NUL-terminated strings, as bytestrings or a combination of these.
+Property values may be defined as an array of 8, 16, 32, or 64-bit integer
+elements, as NUL-terminated strings, as bytestrings or a combination of these.
 
-* Arrays of cells are represented by angle brackets surrounding a
-  space separated list of C-style integers or character literals.
+* Arrays are represented by angle brackets surrounding a space separated list
+  of C-style integers or character literals.  Array elements default to 32-bits
+  in size.  An array of 32-bit elements is also known as a cell list or a list
+  of cells.  A cell being an unsigned 32-bit integer.
 
 	e.g. interrupts = <17 0xc>;
 
-* A 64-bit value is represented with two 32-bit cells.
+* A 64-bit value can be represented with two 32-bit elements.
 
 	e.g. clock-frequency = <0x00000001 0x00000000>;
 
+* The storage size of an element can be changed using the /bits/ prefix.  The
+  /bits/ prefix allows for the creation of 8, 16, 32, and 64-bit elements.
+  The resulting array will not be padded to a multiple of the default 32-bit
+  element size.
+
+	e.g. interrupts = /bits/ 8 <17 0xc>;
+	e.g. clock-frequency = /bits/ 64 <0x0000000100000000>;
+
 * A NUL-terminated string value is represented using double quotes
   (the property value is considered to include the terminating NUL
   character).
@@ -59,19 +69,20 @@ NUL-terminated strings, as bytestrings or a combination of these.
 	e.g. compatible = "ns16550", "ns8250";
 	     example = <0xf00f0000 19>, "a strange property format";
 
-* In a cell array a reference to another node will be expanded to that
-  node's phandle.  References may by '&' followed by a node's label:
+* In an array a reference to another node will be expanded to that node's
+  phandle.  References may by '&' followed by a node's label:
 	e.g. interrupt-parent = < &mpic >;
   or they may be '&' followed by a node's full path in braces:
 	e.g. interrupt-parent = < &{/soc/interrupt-controller@40000} >;
+  References are only permitted in arrays that have an element size of
+  32-bits.
 
-* Outside a cell array, a reference to another node will be expanded
-  to that node's full path.
+* Outside an array, a reference to another node will be expanded to that
+  node's full path.
 	e.g. ethernet0 = &EMAC0;
 
 * Labels may also appear before or after any component of a property
-  value, or between cells of a cell array, or between bytes of a
-  bytestring.
+  value, or between elements of an array, or between bytes of a bytestring.
 	e.g. reg = reglabel: <0 sizelabel: 0x1000000>;
 	e.g. prop = [ab cd ef byte4: 00 ff fe];
 	e.g. str = start: "string value" end: ;
@@ -108,3 +119,4 @@ Version 1 DTS files have the overall layout:
 
 	-- David Gibson <david@gibson.dropbear.id.au>
 	-- Yoder Stuart <stuart.yoder@freescale.com>
+	-- Anton Staaf <robotboy@chromium.org>