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of: Allow busses with #size-cells=0
It's quite legitimate for a DT node to specify #size-cells=0. One example
is a node that's used to collect a number of non-memory-mapped devices.
In that scenario, there may be multiple child nodes with the same name
(type) thus necessitating the use of unit addresses in node names, and
reg properties:
/ {
regulators {
compatible = "simple-bus";
#address-cells = <1>;
#size-cells = <0>;
regulator@0 {
compatible = "regulator-fixed";
reg = <0>;
...
};
regulator@1 {
compatible = "regulator-fixed";
reg = <1>;
...
};
...
};
};
However, #size-cells=0 prevents translation of reg property values into
the parent node's address space. In turn, this triggers the kernel to
emit error messages during boot, such as:
prom_parse: Bad cell count for /regulators/regulator@0
To prevent printing these error messages for legitimate DT content, a
number of changes are made:
1) of_get_address()/of_get_pci_address() are modified only to validate
the value of #address-cells, and not #size-cells.
2) of_can_translate_address() is added to indicate whether address
translation is possible.
3) of_device_make_bus_id() is modified to name devices based on the
translated address only where possible, and otherwise fall back to
using the (first cell of the) raw untranslated address.
4) of_device_alloc() is modified to create memory resources for a device
only if the address can be translated into the CPU's address space.
Signed-off-by: 
Stephen Warren <swarren@nvidia.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>