linux-kernel - Re: [PATCH 3/3] hwrng: msm

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Message-ID: <20180619040458.GJ25852@vkoul-mobl>
Date:   Tue, 19 Jun 2018 09:34:58 +0530
From:   Vinod <vkoul@...nel.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 3/3] hwrng: msm - Add support for prng v2

On 18-06-18, 11:21, Bjorn Andersson wrote:
> On Mon 18 Jun 07:12 PDT 2018, Vinod Koul wrote:
> 
> > Qcom 8996 and later chips support prng v2 where we need to only
> > implement .read callback for hwrng.
> > 
> 
> The hardware still needs initialization, so I think you should expand
> this to mention that the initialization is moved to secure world and
> that's the reason why we only implement read.
> 
> The question is what happens in projects with other security models.

I did think about that, in those case a DT change would do the trick by
pointing to the TZ EE and loading v1 driver but then is DT board sepcific
or SoC specific, I think latter :(

Can we detect the model..?

> >  	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
> > @@ -154,6 +161,9 @@ static int msm_rng_probe(struct platform_device *pdev)
> >  		return PTR_ERR(rng->clk);
> >  
> >  	rng->hwrng = &msm_rng;
> > +	version = (unsigned long)of_device_get_match_data(&pdev->dev);
> 
> If this is "version" then please make it 1 or 2, if you agree with
> Stephen's suggestion of omitting the initialization of init I think this
> would be better as 0/1 and the variable named "skip_init".

ok will do

-- 
~Vinod