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SubjectRe: [PATCH v2] Exynos : Add support for Exynos random number generator
Some minor comments, otherwise this looks much better than the previous
patch.

On 06/27/12 03:31, Jonghwa Lee wrote:
> This patch supports Exynos SOC's PRNG driver. Exynos's PRNG has 5 seeds and
> 5 random number outputs. Module is excuted under runtime power management control,
> so it activates only while it's in use. Otherwise it will be suspended generally.
> It was tested on PQ board by rngtest program.
>
> Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

This is an incorrect signoff chain. Kyungmin is not sending this so why
are you not the last one to sign off? Who is the author, Kyungmin or
yourself?

> +
> +config HW_RANDOM_EXYNOS
> + tristate "EXYNOS HW random number generator support"
> + depends on HW_RANDOM && ARCH_EXYNOS && HAS_IOMEM && PM_RUNTIME

There is no need to depend on PM_RUNTIME or ARCH_EXYNOS.

> +
> +static int exynos_read(struct hwrng *rng, void *buf,
> + size_t max, bool wait)
> +{
> + struct exynos_rng *exynos_rng = container_of(rng,
> + struct exynos_rng, rng);
> + u32 *data = buf;
> +
> + pm_runtime_get_sync(exynos_rng->dev);
> +
> + exynos_rng_writel(exynos_rng, PRNG_START, 0);
> +
> + do {
> + cpu_relax();
> + } while (!(exynos_rng_readl(exynos_rng,
> + EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE));
> +
> + exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET);

Curious, is this actually required? You poll for the status to say done
and the hardware requires you to write back the done bit after it
signals done?

> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res) {
> + clk_put(exynos_rng->clk);
> + return -ENODEV;
> + }

Pass this through directly to devm_request_and_ioremap() without
checking the return value to save some lines.

> +
> + exynos_rng->mem = devm_request_and_ioremap(&pdev->dev, res);
> + if (!exynos_rng->mem) {
> + dev_err(&pdev->dev, "Ioremap failed.\n");

devm_request_and_ioremap() already prints a message on failure to remap
so this is unnecessary printk.

> + return -EBUSY;
> + }
> +
> + platform_set_drvdata(pdev, exynos_rng);
> +
> + pm_runtime_enable(&pdev->dev);
> +
> + ret = hwrng_register(&exynos_rng->rng);
> + if (ret)
> + return ret;
> +
> + return 0;

Why not just 'return hwrng_register()'?

> +
> +static int exynos_rng_runtime_resume(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct exynos_rng *exynos_rng = platform_get_drvdata(pdev);
> +
> + clk_prepare_enable(exynos_rng->clk);
> + return 0;

Perhaps return the value of clk_prepare_enable() in case it fails for
some reason?

--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.



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