[PATCH 2/6] mtd: physmap_of: add a hook for Versatile write protection

Linus Walleij linus.walleij at linaro.org
Sat Feb 13 05:19:40 PST 2016


Hey MTD folks,

On Tue, Jan 26, 2016 at 12:12 PM, Linus Walleij
<linus.walleij at linaro.org> wrote:

> In order to support device tree probing of Versatile NOR flash
> chips, there must be a way to add the VPP (write protection)
> enable/disable callback. The register in question is in the
> system controllers of these machines. Apart from this quirk,
> the ARM flash chips are standard CFI flash chips from various
> vendors.
>
> Additionally, the Integrator/AP require you to set up the external
> bus interface (EBI) to allow writes to the chip select where the
> flash memory is connected.
>
> Solve this by looking for the arm,versatile-flash compatible
> string in the flash device tree node. In the driver,
> add a special hook to check for the various Versatile syscons and
> register a callback for .set_vpp() if this compatible is present.
>
> Provide a special Kconfig entry for the addon hook so it will
> not be compiled in if the Versatile boards are not supported.
> Stubs in the header file make sure the impact will be zero on
> other platforms. (Compilers optimze this out.)
>
> With this patch, a large slew of ARM board file code can be
> removed.
>
> Cc: Grant Likely <grant.likely at linaro.org>
> Cc: Rob Herring <robh at kernel.org>
> Cc: Arnd Bergmann <arnd at arndb.de>
> Signed-off-by: Linus Walleij <linus.walleij at linaro.org>

Do you think my reply to this about reference counting and
subsequent (accepted) patch to update the documentation
to reflect 876fe76d793d03077
"mtd: maps: physmap: Add reference counter to set_vpp()"
is enough to warrant merging of this?

If you want the code developed in any special direction
just tell me.

Yours,
Linus Walleij



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