[U-Boot] [PATCH v4 8/8] sandbox: Add basic command line parsing

[Mike Frysinger <vapier@gentoo.org>]

On Monday 27 February 2012 00:43:30 Simon Glass wrote:
> On Sun, Feb 26, 2012 at 8:42 PM, Mike Frysinger wrote:
> > drivers/mtd/spi/sandbox.c:
> > static int sb_cmdline_cb_spi_sf(struct sandbox_state *state, const char
> > *arg) {
> >    unsigned long bus, cs;
> >    const char *spec = sb_spi_parse_spec(arg, &bus, &cs);
> > 
> >    if (!spec)
> >        return 1;
> > 
> >    state->spi[bus][cs][0] = &sb_sf_ops;
> >    state->spi[bus][cs][1] = spec;
> >    return 0;
> > }
> > SB_CMDLINE_OPT(spi_sf, 1, "connect a SPI flash: <bus>:<cs>:<id>:<file>");
> 
> sandbox...give me your address and I'll send you a cheque to cover the
> bytes so used :-)

it'll have to be a big one to stop the cascading line wrapping :P

> > and people could do:
> >        ./u-boot --spi_sf 0:3:m25p16:./some-file.bin
> > this would connect the spi flash simulation up to the simulated spi bus 0
> > on cs 3 and have it simulate a m25p16 flash with "some-file.bin" backing
> > it.
> > 
> > if someone were to enter the wrong value for
> > "0:3:m25p16:./some-file.bin", how do you propose we communicate that ?
> >  the existing code can easily signal the higher parsing logic via return
> > values, but then we'd just get:
> >        failed to parse option: 0:3:m25p16:./some-file.bin
> > 
> > but what exactly did the code not like ?  was it the bus # ?  the cs # ?
> >  the spi flash id ?  the backing file ?  if the getopt code has access
> > to printf(), we can clearly communicate to the user what is going wrong.
> 
> Yes I think printf() is useful in getopt, I just would prefer to avoid
> using U-Boot's printf. It goes through all the console code, and we
> might be running a test that deliberately breaks that, perhaps.
> Actually this could be a pretty important thing to sort out - we need
> to keep a clear boundary between test code and U-Boot code (as we
> discussed over GPIO). Having the test code use U-Boot's printf() is
> blurring that.

we probably need to add architecture details like this to doc/README.sandbox 
so we can stay on the same page ...

> To your example, if the syntax is correct perhaps, then it got through
> initial parsing. If the filename is wrong, or the bus number, then
> perhaps there will be a message and failure much later. Perhaps the
> initial parsing just does what it can to avoid running past an obvious
> syntax error. But we can't really know success until we open the file,
> or try the bus.

if the bus/cs are valid, the rest of the parsing is delayed until you do "sf 
probe" at which point you'd get an explanation of what is wrong.  i guess we 
can live with this for now.
-mike
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