[PATCH] powerpc/powernv/flash: Check OPAL flash calls exist before using

[Michael Ellerman]

Vasant Hegde <hegdevasant at linux.vnet.ibm.com> writes:
> Currently only FSP based powernv systems supports firmware update
> interfaces. Hence check that the token OPAL_FLASH_VALIDATE exists
> before initalising the flash driver.
>
> Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
> ---
>  arch/powerpc/platforms/powernv/opal-flash.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/powerpc/platforms/powernv/opal-flash.c b/arch/powerpc/platforms/powernv/opal-flash.c
> index 7e7d38b17420..05490fc22fae 100644
> --- a/arch/powerpc/platforms/powernv/opal-flash.c
> +++ b/arch/powerpc/platforms/powernv/opal-flash.c
> @@ -520,6 +520,10 @@ void __init opal_flash_update_init(void)
>  {
>  	int ret;
>  
> +	/* Firmware update is not supported by firmware */
> +	if (!opal_check_token(OPAL_FLASH_VALIDATE))
> +		return;
> +

That will mean the following files no longer appear on BMC systems:

  /sys/firmware/opal/image
  /sys/firmware/opal/validate_flash
  /sys/firmware/opal/manage_flash
  /sys/firmware/opal/update_flash

Presumably those files don't actually work correctly, but are we sure
their mere existence isn't used by anything at all?

We've had trouble in the past where removing sysfs files breaks tools
unexpectedly, see smt_snooze_delay.

cheers