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Date:   Thu, 13 Apr 2017 13:06:43 +0200
From:   Corentin Labbe <clabbe.montjoie@...il.com>
To:     sean.wang@...iatek.com
Cc:     herbert@...dor.apana.org.au, mpm@...enic.com, robh+dt@...nel.org,
        mark.rutland@....com, prasannatsmkumar@...il.com,
        romain.perier@...e-electrons.com, shannon.nelson@...cle.com,
        weiyongjun1@...wei.com, devicetree@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        keyhaede@...il.com
Subject: Re: [PATCH 2/2] hwrng: mtk: Add driver for hardware random generator
 on MT7623 SoC

Hello

I have some minor comment below:

On Thu, Apr 13, 2017 at 03:05:08PM +0800, sean.wang@...iatek.com wrote:
> From: Sean Wang <sean.wang@...iatek.com>
> 
> This patch adds support for hardware random generator on MT7623 SoC
> and should also work on other similar Mediatek SoCs. Currently,
> the driver is already tested successfully with rng-tools.
> 
> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> ---
>  drivers/char/hw_random/Kconfig   |  16 +++-
>  drivers/char/hw_random/Makefile  |   2 +-
>  drivers/char/hw_random/mtk-rng.c | 174 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 190 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/char/hw_random/mtk-rng.c
> 
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index 0cafe08..af782ce 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -419,10 +419,24 @@ config HW_RANDOM_CAVIUM
>           Generator hardware found on Cavium SoCs.
>  
>           To compile this driver as a module, choose M here: the
> -         module will be called cavium_rng.
> +         module will be called mtk-rng.

Unwanted change

>  
>           If unsure, say Y.
>  
> +config HW_RANDOM_MTK
> +	tristate "Mediatek Random Number Generator support"
> +	depends on HW_RANDOM
> +	depends on ARCH_MEDIATEK || COMPILE_TEST
> +	default y
> +	---help---
> +	  This driver provides kernel-side support for the Random Number
> +	  Generator hardware found on Mediatek SoCs.
> +
> +	  To compile this driver as a module, choose M here. the
> +	  module will be called mtk-rng.
> +
> +	  If unsure, say Y.
> +
>  endif # HW_RANDOM
>  
>  config UML_RANDOM
> diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
> index 5f52b1e..68be716 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -1,7 +1,6 @@
>  #
>  # Makefile for HW Random Number Generator (RNG) device drivers.
>  #
> -

Another unwanted change

>  obj-$(CONFIG_HW_RANDOM) += rng-core.o
>  rng-core-y := core.o
>  obj-$(CONFIG_HW_RANDOM_TIMERIOMEM) += timeriomem-rng.o
> @@ -36,3 +35,4 @@ obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
>  obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
>  obj-$(CONFIG_HW_RANDOM_MESON) += meson-rng.o
>  obj-$(CONFIG_HW_RANDOM_CAVIUM) += cavium-rng.o cavium-rng-vf.o
> +obj-$(CONFIG_HW_RANDOM_MTK)	+= mtk-rng.o
> diff --git a/drivers/char/hw_random/mtk-rng.c b/drivers/char/hw_random/mtk-rng.c
> new file mode 100644
> index 0000000..6561ee0
> --- /dev/null
> +++ b/drivers/char/hw_random/mtk-rng.c
> @@ -0,0 +1,174 @@
> +/*
> + * Driver for Mediatek Hardware Random Number Generator
> + *
> + * Copyright (C) 2017 Sean Wang <sean.wang@...iatek.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +#define MTK_RNG_DEV KBUILD_MODNAME
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/hw_random.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +#define USEC_POLL			2
> +#define TIMEOUT_POLL			20
> +
> +#define RNG_CTRL			0x00
> +#define  RNG_EN				BIT(0)
> +#define  RNG_READY			BIT(31)

Keep only one space between define and name

> +
> +#define RNG_DATA			0x08
> +
> +#define to_mtk_rng(p)	container_of(p, struct mtk_rng, rng)
> +
> +struct mtk_rng {
> +	struct device	*dev;
> +	void __iomem *base;
> +	struct clk *clk;
> +	struct hwrng rng;
> +};
> +
> +static int mtk_rng_init(struct hwrng *rng)
> +{
> +	struct mtk_rng *priv = to_mtk_rng(rng);
> +	u32 val;
> +	int err;
> +
> +	err = clk_prepare_enable(priv->clk);
> +	if (err)
> +		return err;
> +
> +	val = readl(priv->base + RNG_CTRL);
> +	val |= RNG_EN;
> +	writel(val, priv->base + RNG_CTRL);
> +
> +	return 0;
> +}
> +
> +static void mtk_rng_cleanup(struct hwrng *rng)
> +{
> +	struct mtk_rng *priv = to_mtk_rng(rng);
> +	u32 val;
> +
> +	val = readl(priv->base + RNG_CTRL);
> +	val &= ~RNG_EN;
> +	writel(val, priv->base + RNG_CTRL);
> +
> +	clk_disable_unprepare(priv->clk);
> +}
> +
> +static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait)
> +{
> +	struct mtk_rng *priv = to_mtk_rng(rng);
> +	int ready;
> +
> +	ready = readl(priv->base + RNG_CTRL) & RNG_READY;
> +	if (!ready && wait)
> +		readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready,
> +					  ready & RNG_READY, USEC_POLL,
> +					  TIMEOUT_POLL);
> +	return !!ready;
> +}
> +
> +static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
> +{
> +	struct mtk_rng *priv = to_mtk_rng(rng);
> +	int retval = 0;
> +
> +	while (max >= sizeof(u32)) {
> +		if (!mtk_rng_wait_ready(rng, wait))
> +			break;
> +
> +		*(u32 *)buf = readl(priv->base + RNG_DATA);
> +		retval += sizeof(u32);
> +		buf += sizeof(u32);
> +		max -= sizeof(u32);
> +	}
> +
> +	if (unlikely(wait && max))
> +		dev_warn(priv->dev, "timeout might be not properly set\n");
> +
> +	return retval || !wait ? retval : -EIO;
> +}
> +
> +static int mtk_rng_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	int ret;
> +	struct mtk_rng *priv;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(&pdev->dev, "no iomem resource\n");
> +		return -ENXIO;
> +	}
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->dev = &pdev->dev;
> +	priv->rng.name = pdev->name;
> +	priv->rng.init = mtk_rng_init;
> +	priv->rng.cleanup = mtk_rng_cleanup;
> +	priv->rng.read = mtk_rng_read;
> +
> +	priv->clk = devm_clk_get(&pdev->dev, "rng");
> +	if (IS_ERR(priv->clk)) {
> +		ret = PTR_ERR(priv->clk);
> +		dev_err(&pdev->dev, "no clock for device: %d\n", ret);
> +		return ret;
> +	}
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

You get that resource twice

Regards
Corentin Labbe

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