[PATCH/RFC] soc: bcm2835: Make !RASPBERRYPI_FIRMWARE dummies return failure

[eric@anholt.net (Eric Anholt)]

Geert Uytterhoeven <geert@linux-m68k.org> writes:

> If CONFIG_RASPBERRYPI_FIRMWARE=n:
>
>     drivers/gpio/gpio-raspberrypi-exp.c: In function ?rpi_exp_gpio_get_polarity?:
>     drivers/gpio/gpio-raspberrypi-exp.c:71: warning: ?get.polarity? is used uninitialized in this function
>     drivers/gpio/gpio-raspberrypi-exp.c: In function ?rpi_exp_gpio_get_direction?:
>     drivers/gpio/gpio-raspberrypi-exp.c:150: warning: ?get.direction? is used uninitialized in this function
>
> The dummy firmware interface functions return 0, which means success,
> causing subsequent code to make use of the never initialized output
> parameter.
>
> Fix this by making the dummy functions return an error code (-ENOSYS)
> instead.
>
> Note that this assumes the firmware always fills in the requested data
> in the CONFIG_RASPBERRYPI_FIRMWARE=y case.
>
> Fixes: d45f1a563b92dac7 ("staging: vc04_services: fix up rpi firmware functions")
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

You should definitely not be calling these if rpi_firmware_get() failed,
so this seems like a good solution.

Reviewed-by: Eric Anholt <eric@anholt.net>
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