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The nvmem cell binding applies to all eeprom child nodes matching
"^.*@[0-9a-f]+$" without taking a compatible into account.

Linux drivers, like at24, are even more extensive and assume
_all_ at24 eeprom child nodes to be nvmem cells since e888d445
("nvmem: resolve cells from DT at registration time").

Since df5f3b6f ("dt-bindings: nvmem: stm32: new property for
data access"), the additionalProperties: True means it's Ok to have
other properties as long as they don't match "^.*@[0-9a-f]+$".

The barebox bootloader extends the MTD partitions binding to
EEPROM and can fix up following device tree node:

  &eeprom {
    partitions {
      compatible = "fixed-partitions";
    };
  };

This is allowed binding-wise, but drivers using nvmem_register()
like at24 will fail to parse because the function expects all child
nodes to have a reg property present. This results in the whole
EEPROM driver probe failing despite the device tree being correct.

Fix this by skipping nodes lacking a reg property instead of
returning an error. This effectively makes the drivers adhere
to the binding because all nodes with a unit address must have
a reg property and vice versa.

Fixes: e888d445

 ("nvmem: resolve cells from DT at registration time").
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20210129171430.11328-6-srinivas.kandagatla@linaro.org

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>