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SubjectRe: [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@mediatek.com wrote:
> From: Sean Wang <sean.wang@mediatek.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@mediatek.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@mediatek.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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