Re: [PATCH v6 07/11] platform: cznic: turris-omnia-mcu: Add support for MCU provided TRNG

[Andy Shevchenko <andy@kernel.org>]

On Thu, Apr 18, 2024 at 02:11:12PM +0200, Marek Behún wrote:
> Add support for true random number generator provided by the MCU.
> New Omnia boards come without the Atmel SHA204-A chip. Instead the
> crypto functionality is provided by new microcontroller, which has
> a TRNG peripheral.

...

> +int omnia_mcu_register_trng(struct omnia_mcu *mcu)
> +{
> +	struct device *dev = &mcu->client->dev;
> +	int irq, err;
> +	u8 irq_idx;
> +
> +	if (!(mcu->features & FEAT_TRNG))
> +		return 0;

> +	irq_idx = omnia_int_to_gpio_idx[__bf_shf(INT_TRNG)];
> +	irq = devm_irq_create_mapping(dev, mcu->gc.irq.domain, irq_idx);
> +	if (irq < 0)
> +		return dev_err_probe(dev, irq, "Cannot map TRNG IRQ\n");

This looks like some workaround against existing gpiod_to_irq(). Why do you
need this?

> +	init_completion(&mcu->trng_completion);
> +
> +	err = devm_request_threaded_irq(dev, irq, NULL, omnia_trng_irq_handler,
> +					IRQF_ONESHOT, "turris-omnia-mcu-trng",
> +					mcu);
> +	if (err)
> +		return dev_err_probe(dev, err, "Cannot request TRNG IRQ\n");
> +
> +	mcu->trng.name = "turris-omnia-mcu-trng";
> +	mcu->trng.read = omnia_trng_read;
> +	mcu->trng.priv = (unsigned long)mcu;
> +
> +	err = devm_hwrng_register(dev, &mcu->trng);
> +	if (err)
> +		return dev_err_probe(dev, err, "Cannot register TRNG\n");
> +
> +	return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko