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[POWERPC] Xilinx: Update booting-without-of.
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This now better describes what the UBoot device tree generator
actually does.  In particular:

1) Nodes have a label derived from the device name, and a node name
derived from a generic version of the device type, e.g. 'ethernet',
'serial', etc.

2) Usage of compound nodes (representing more than one device in the
same IP) which actually works.  This requires having a valid
compatible node, and all the other things that a bus normally has.
I've chosen 'xlnx,compound' as the bus name to describe these compound
nodes.

In addition, I've clarified some of the language relating to how mhs
nodes should be represent in the device tree.

Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
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stephenneuendorffer authored and glikely committed Jan 9, 2008
1 parent faa6511 commit ab99eee
Showing 1 changed file with 33 additions and 23 deletions.
56 changes: 33 additions & 23 deletions Documentation/powerpc/booting-without-of.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -2292,7 +2292,7 @@ platforms are moved over to use the flattened-device-tree model.
properties of the device node. In general, device nodes for IP-cores
will take the following form:

(name)@(base-address) {
(name): (generic-name)@(base-address) {
compatible = "xlnx,(ip-core-name)-(HW_VER)"
[, (list of compatible devices), ...];
reg = <(baseaddr) (size)>;
Expand All @@ -2302,6 +2302,9 @@ platforms are moved over to use the flattened-device-tree model.
xlnx,(parameter2) = <(int-value)>;
};

(generic-name): an open firmware-style name that describes the
generic class of device. Preferably, this is one word, such
as 'serial' or 'ethernet'.
(ip-core-name): the name of the ip block (given after the BEGIN
directive in system.mhs). Should be in lowercase
and all underscores '_' converted to dashes '-'.
Expand All @@ -2310,9 +2313,9 @@ platforms are moved over to use the flattened-device-tree model.
dropped from the parameter name, the name is converted
to lowercase and all underscore '_' characters are
converted to dashes '-'.
(baseaddr): the C_BASEADDR parameter.
(baseaddr): the baseaddr parameter value (often named C_BASEADDR).
(HW_VER): from the HW_VER parameter.
(size): equals C_HIGHADDR - C_BASEADDR + 1
(size): the address range size (often C_HIGHADDR - C_BASEADDR + 1).

Typically, the compatible list will include the exact IP core version
followed by an older IP core version which implements the same
Expand Down Expand Up @@ -2342,11 +2345,11 @@ platforms are moved over to use the flattened-device-tree model.

becomes the following device tree node:

opb-uartlite-0@ec100000 {
opb_uartlite_0: serial@ec100000 {
device_type = "serial";
compatible = "xlnx,opb-uartlite-1.00.b";
reg = <ec100000 10000>;
interrupt-parent = <&opb-intc>;
interrupt-parent = <&opb_intc_0>;
interrupts = <1 0>; // got this from the opb_intc parameters
current-speed = <d#115200>; // standard serial device prop
clock-frequency = <d#50000000>; // standard serial device prop
Expand All @@ -2355,16 +2358,19 @@ platforms are moved over to use the flattened-device-tree model.
xlnx,use-parity = <0>;
};

Some IP cores actually implement 2 or more logical devices. In this case,
the device should still describe the whole IP core with a single node
and add a child node for each logical device. The ranges property can
be used to translate from parent IP-core to the registers of each device.
(Note: this makes the assumption that both logical devices have the same
bus binding. If this is not true, then separate nodes should be used for
each logical device). The 'cell-index' property can be used to enumerate
logical devices within an IP core. For example, the following is the
system.mhs entry for the dual ps2 controller found on the ml403 reference
design.
Some IP cores actually implement 2 or more logical devices. In
this case, the device should still describe the whole IP core with
a single node and add a child node for each logical device. The
ranges property can be used to translate from parent IP-core to the
registers of each device. In addition, the parent node should be
compatible with the bus type 'xlnx,compound', and should contain
#address-cells and #size-cells, as with any other bus. (Note: this
makes the assumption that both logical devices have the same bus
binding. If this is not true, then separate nodes should be used
for each logical device). The 'cell-index' property can be used to
enumerate logical devices within an IP core. For example, the
following is the system.mhs entry for the dual ps2 controller found
on the ml403 reference design.

BEGIN opb_ps2_dual_ref
PARAMETER INSTANCE = opb_ps2_dual_ref_0
Expand All @@ -2386,21 +2392,24 @@ platforms are moved over to use the flattened-device-tree model.

It would result in the following device tree nodes:

opb_ps2_dual_ref_0@a9000000 {
opb_ps2_dual_ref_0: opb-ps2-dual-ref@a9000000 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "xlnx,compound";
ranges = <0 a9000000 2000>;
// If this device had extra parameters, then they would
// go here.
ps2@0 {
compatible = "xlnx,opb-ps2-dual-ref-1.00.a";
reg = <0 40>;
interrupt-parent = <&opb-intc>;
interrupt-parent = <&opb_intc_0>;
interrupts = <3 0>;
cell-index = <0>;
};
ps2@1000 {
compatible = "xlnx,opb-ps2-dual-ref-1.00.a";
reg = <1000 40>;
interrupt-parent = <&opb-intc>;
interrupt-parent = <&opb_intc_0>;
interrupts = <3 0>;
cell-index = <0>;
};
Expand Down Expand Up @@ -2463,29 +2472,30 @@ platforms are moved over to use the flattened-device-tree model.

Gives this device tree (some properties removed for clarity):

plb-v34-0 {
plb@0 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "xlnx,plb-v34-1.02.a";
device_type = "ibm,plb";
ranges; // 1:1 translation

plb-bram-if-cntrl-0@ffff0000 {
plb_bram_if_cntrl_0: bram@ffff0000 {
reg = <ffff0000 10000>;
}

opb-v20-0 {
opb@20000000 {
#address-cells = <1>;
#size-cells = <1>;
ranges = <20000000 20000000 20000000
60000000 60000000 20000000
80000000 80000000 40000000
c0000000 c0000000 20000000>;

opb-uart16550-0@a0000000 {
opb_uart16550_0: serial@a0000000 {
reg = <a00000000 2000>;
};

opb-intc-0@d1000fc0 {
opb_intc_0: interrupt-controller@d1000fc0 {
reg = <d1000fc0 20>;
};
};
Expand Down

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