linux-kernel - Re: [PATCH] Add Ingenic JZ4780 hardware RNG driver

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Message-ID: <92a00062-9a87-0053-2c99-17bd1a304a4a@gmail.com>
Date:	Wed, 17 Aug 2016 21:06:55 +0200
From:	Corentin LABBE <clabbe.montjoie@...il.com>
To:	PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
	mpm@...enic.com, herbert@...dor.apana.org.au, robh+dt@...nel.org,
	mark.rutland@....com, ralf@...ux-mips.org, davem@...emloft.net,
	geert@...ux-m68k.org, akpm@...ux-foundation.org,
	gregkh@...uxfoundation.org, mchehab@...nel.org, linux@...ck-us.net,
	boris.brezillon@...e-electrons.com, harvey.hunt@...tec.com,
	alex.smith@...tec.com, daniel.thompson@...aro.org,
	lee.jones@...aro.org, f.fainelli@...il.com, kieran@...uared.org.uk,
	krzk@...nel.org, joshua.henderson@...rochip.com,
	yendapally.reddy@...adcom.com, narmstrong@...libre.com,
	wangkefeng.wang@...wei.com, chunkeey@...glemail.com,
	noltari@...il.com, linus.walleij@...aro.org, pankaj.dev@...com,
	mathieu.poirier@...aro.org, linux-crypto@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mips@...ux-mips.org
Subject: Re: [PATCH] Add Ingenic JZ4780 hardware RNG driver

Hello

I have just some minor comments below

> diff --git a/drivers/char/hw_random/jz4780-rng.c b/drivers/char/hw_random/jz4780-rng.c
> new file mode 100644
> index 0000000..c9d2cde
> --- /dev/null
> +++ b/drivers/char/hw_random/jz4780-rng.c
> @@ -0,0 +1,105 @@
> +/*
> + * jz4780-rng.c - Random Number Generator driver for J4780
> + *
> + * Copyright 2016 (C) PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>
> + *
> + * This file is licensed under  the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/hw_random.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/io.h>
> +#include <linux/platform_device.h>
> +#include <linux/err.h>

You could sort them by alphabetical order

> +
> +#define REG_RNG_CTRL	0x0
> +#define REG_RNG_DATA	0x4
> +
> +struct jz4780_rng {
> +	struct device *dev;
> +	struct hwrng rng;
> +	void __iomem *mem;
> +};
> +
> +static u32 jz4780_rng_readl(struct jz4780_rng *rng, u32 offset)
> +{
> +	return readl(rng->mem + offset);
> +}
> +
> +static void jz4780_rng_writel(struct jz4780_rng *rng, u32 val, u32 offset)
> +{
> +	writel(val, rng->mem + offset);
> +}
> +
> +static int jz4780_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
> +{
> +	struct jz4780_rng *jz4780_rng = container_of(rng, struct jz4780_rng,
> +							rng);
> +	u32 *data = buf;
> +	*data = jz4780_rng_readl(jz4780_rng, REG_RNG_DATA);
> +	return 4;
> +}

If max is less than 4, its bad

> +
> +static int jz4780_rng_probe(struct platform_device *pdev)
> +{
> +	struct jz4780_rng *jz4780_rng;
> +	struct resource *res;
> +	resource_size_t size;
> +	int ret;
> +
> +	jz4780_rng = devm_kzalloc(&pdev->dev, sizeof(struct jz4780_rng),
> +					GFP_KERNEL);

You could write sizeof(*js480_rng)

> +	if (!jz4780_rng)
> +		return -ENOMEM;
> +
> +	jz4780_rng->dev = &pdev->dev;
> +	jz4780_rng->rng.name = "jz4780";
> +	jz4780_rng->rng.read = jz4780_rng_read;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	size = resource_size(res);
> +
> +	jz4780_rng->mem = devm_ioremap(&pdev->dev, res->start, size);
You could save code by using devm_ioremap_resource (don't need size)

> +	if (IS_ERR(jz4780_rng->mem))
> +		return PTR_ERR(jz4780_rng->mem);
> +
> +	platform_set_drvdata(pdev, jz4780_rng);
> +	jz4780_rng_writel(jz4780_rng, 1, REG_RNG_CTRL);
> +	ret = hwrng_register(&jz4780_rng->rng);
> +
> +	return ret;
> +}
You could write directly return hwrng_register(..)

Regards

LABBE Corentin