[U-Boot-Users] [patch] add support for "eeprom info"

[Mike Frysinger]

On Wednesday 23 January 2008, Wolfgang Denk wrote:
> In message <200801231113.38864.vapier at gentoo.org> you wrote:
> > This patch adds a new sub command to eeprom called "info".  This allows
> > eeprom driver writers to implement a way of querying the device.  For
> > example, SPI flashes have status commands, jedec ids, part ids, and other
> > fun stuff.  It's useful to be able to quickly probe this data (so you
> > know things are detected properly and all that jazz).
>
> How is this suppoesed to work on the "normal" EEPROm devices which are
> typically attached to the I2C bus?
>
> > I made the function weak so that people aren't required to implement this
> > function (mostly so that it does not break all the SPI drivers out there
> > right now).
>
> ... and I2C.

i have no idea, i dont use i2c flashes.  i dont know if there is any standard 
for them.  if there isnt, easy enough to protect with CONFIG_SPI.

> > +extern int  eeprom_info (void) __attribute__((weak));
> >  #if defined(CFG_EEPROM_WREN)
> >  extern int eeprom_write_enable (unsigned dev_addr, int state);
> >  #endif
> > @@ -104,7 +105,8 @@ int do_eeprom ( cmd_tbl_t * cmdtp, int flag, int
> > argc, char *argv[])
> >
> >  			puts ("done\n");
> >  			return rcode;
> > -		}
> > +		} else if (argc == 2 && eeprom_info && strcmp (argv[1], "info") == 0)
> > +			return eeprom_info ();
>
> ... && eeprom_info && ...?
>
> Does that mean that a weak function resolves to a NULL pointer? Is
> this guaranteed?

of course.  an undefined weak function resolves to 0.
-mike
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