Messages in this thread | | | Date | Thu, 28 Jun 2012 09:20:47 +0900 | From | jonghwa3.lee@samsung ... | Subject | Re: [PATCH v2] Exynos : Add support for Exynos random number generator |
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On 2012년 06월 28일 02:52, Stephen Boyd wrote:
> 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? >
I'm author. Okay, I'll leave my name only.
>> + >> +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? >
Yes, It's hardware's own characteristic. It needs to be written 1 on status register to clear it.
>> + >> + 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? >
Okay, I agree with your opinion all.
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