RE: [PATCH v3 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC

[JiaJie Ho]

> -----Original Message-----
> From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Sent: 10 January, 2023 3:41 PM
> To: JiaJie Ho <jiajie.ho@xxxxxxxxxxxxxxxx>
> Cc: Olivia Mackall <olivia@xxxxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>;
> Krzysztof Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx>; Emil Renner
> Berthing <kernel@xxxxxxxx>; Conor Dooley <conor.dooley@xxxxxxxxxxxxx>;
> linux-crypto@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; linux-riscv@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 2/3] hwrng: starfive - Add TRNG driver for StarFive
> SoC
> 
> On Tue, Jan 10, 2023 at 12:52:48AM +0800, Jia Jie Ho wrote:
> >
> > +static irqreturn_t starfive_trng_irq(int irq, void *priv) {
> > +	u32 status;
> > +	struct starfive_trng *trng = (struct starfive_trng *)priv;
> > +
> > +	status = readl(trng->base + STARFIVE_ISTAT);
> > +	if (status & STARFIVE_ISTAT_RAND_RDY) {
> > +		writel(STARFIVE_ISTAT_RAND_RDY, trng->base +
> STARFIVE_ISTAT);
> > +		complete(&trng->random_done);
> > +	}
> > +
> > +	if (status & STARFIVE_ISTAT_SEED_DONE) {
> > +		writel(STARFIVE_ISTAT_SEED_DONE, trng->base +
> STARFIVE_ISTAT);
> > +		complete(&trng->reseed_done);
> > +	}
> > +
> > +	if (status & STARFIVE_ISTAT_LFSR_LOCKUP) {
> > +		writel(STARFIVE_ISTAT_LFSR_LOCKUP, trng->base +
> STARFIVE_ISTAT);
> > +		/* SEU occurred, reseeding required*/
> > +		writel(STARFIVE_CTRL_EXEC_RANDRESEED, trng->base +
> STARFIVE_CTRL);
> 
> This could occur at the same time as a GENE_RANDNUM write so perhaps
> you should add some locking?
> 

I'll add those in the next version.

> > +	ret = devm_request_irq(&pdev->dev, irq, starfive_trng_irq, 0, pdev-
> >name,
> > +			       (void *)trng);
> > +	if (ret)
> > +		return dev_err_probe(&pdev->dev, irq,
> > +				     "Failed to register interrupt handler\n");
> 
> ...
> 
> > +	init_completion(&trng->random_done);
> > +	init_completion(&trng->reseed_done);
> 
> These completion initialisations should be moved above the IRQ registration
> because you should always be prepared to get spurious interrupts.
> 

Will update these too.

> Otherwise the patch looks good.
> 

Thanks again for reviewing the patch and providing the useful feedbacks.

Best regards,
Jia Jie