The recent change to the lexer to only recognize property and node
names in the appropriate context removed a number of lexical warts in
our language that would have gotten ugly as we add expression support
and so forth.
But there's one nasty one remaining: references can contain a full
path, including the various problematic node name characters (',', '+'
and '-', for example). This would cause trouble with expressions, and
it also causes trouble with the patch I'm working on to allow
expanding references to paths rather than phandles. This patch
therefore reworks the lexer to mitigate these problems.
- References to labels cause no problems. These are now
recognized separately from references to full paths. No syntax change
here.
- References to full paths, including problematic characters
are allowed by "quoting" the path with braces
e.g. &{/pci@10000/somedevice@3,8000}. The braces protect any internal
problematic characters from being confused with operators or whatever.
- For compatibility with existing dts files, in v0 dts files
we allow bare references to paths as before &/foo/bar/whatever - but
*only* if the path contains no troublesome characters. Specifically
only [a-zA-Z0-9_@/] are allowed.
This is an incompatible change to the dts-v1 format, but since AFAIK
no-one has yet switched to dts-v1 files, I think we can get away with
it. Better to make the transition when people to convert to v1, and
get rid of the problematic old syntax.
Strictly speaking, it's also an incompatible change to the v0 format,
since some path references that were allowed before are no longer
allowed. I suspect no-one has been using the no-longer-supported
forms (certainly none of the kernel dts files will cause trouble).
We might need to think about this harder, though.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
dtc: Flexible tree checking infrastructure
Here, at last, is a substantial start on revising dtc's infrastructure
for checking the tree; this is the rework I've been saying was
necessary practically since dtc was first release.
In the new model, we have a table of "check" structures, each with a
name, references to checking functions, and status variables. Each
check can (in principle) be individually switched off or on (as either
a warning or error). Checks have a list of prerequisites, so if
checks need to rely on results from earlier checks to make sense (or
even to avoid crashing) they just need to list the relevant other
checks there.
For now, only the "structural" checks and the fixups for phandle
references are converted to the new mechanism. The rather more
involved semantic checks (which is where this new mechanism will
really be useful) will have to be converted in future patches.
At present, there's no user interface for turning on/off the checks -
the -f option now forces output even if "error" level checks fail.
Again, future patches will be needed to add the fine-grained control,
but that should be quite straightforward with the infrastructure
implemented here.
Also adds a testcase for the handling of bad references, which catches
a bug encountered while developing this patch.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
