[PATCH] rng: meson: make core clock optional

[Scott K Logan]

On Fri, 2020-09-25 at 09:19 +0200, Neil Armstrong wrote:
> This fixes HWRNG support on Amlogic GXL, GXM, G12A, G12B & SM1
> based boards dues to the lack of the core clock in the device tree.
> 
> It was reported breaking EFI boot in the Linux EFI stub, because the
> EFI_RNG_PROTOCOL didn't check for the RNG device presence before
> installing itself.
> 
> The Linux amlogic,meson-rng.yaml doesn't mandate the core clock,
> this the clock should be ignores if not present.
> 
> Nevertheless, the clock should be present and this should be fixed
> on the Linux meson-gxl.dtsi & meson-g12-common.dtsi then synced
> with U-Boot.
> 
> The change has been tested on a Khadas VIM3, which uses the common
> meson-g12-common.dtsi like the Odroid-C4 & Odroid-N2 in Scott's
> report, along with the RNG cmd.
> 
> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Reported-by: Scott K Logan <logans at cottsay.net>
> Fixes: bc40eb278b ("drivers/rng: add Amlogic hardware RNG driver")
> Signed-off-by: Neil Armstrong <narmstrong at baylibre.com>
> ---
>  drivers/rng/meson-rng.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/rng/meson-rng.c b/drivers/rng/meson-rng.c
> index 4b81a62353..57a5a702a2 100644
> --- a/drivers/rng/meson-rng.c
> +++ b/drivers/rng/meson-rng.c
> @@ -90,8 +90,9 @@ static int meson_rng_ofdata_to_platdata(struct
> udevice *dev)
>  	if (!pdata->base)
>  		return -ENODEV;
>  
> +	/* Get optional "core" clock */
>  	err = clk_get_by_name(dev, "core", &pdata->clk);
> -	if (err)
> +	if (err && err != -ENODATA)
>  		return err;
>  
>  	return 0;
> -- 
> 2.22.0

Tested-by: Scott K Logan <logans at cottsay.net>