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Message-id: <87bmjc9dlr.fsf%l.stelmach@samsung.com>
Date: Wed, 06 Dec 2017 14:42:56 +0100
From: Łukasz Stelmach <l.stelmach@...sung.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: robh+dt@...nel.org, Stephan Mueller <smueller@...onox.de>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>,
Kukjin Kim <kgene@...nel.org>, linux-crypto@...r.kernel.org,
linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
Marek Szyprowski <m.szyprowski@...sung.com>,
Bartłomiej Żołnierkiewicz
<b.zolnierkie@...sung.com>
Subject: Re: [PATCH 1/3] crypto: exynos - Support Exynos5250+ SoCs
It was <2017-12-05 wto 14:34>, when Krzysztof Kozlowski wrote:
> On Tue, Dec 5, 2017 at 1:35 PM, Łukasz Stelmach <l.stelmach@...sung.com> wrote:
>> Add support for PRNG in Exynos5250+ SoCs.
>>
>> Signed-off-by: Łukasz Stelmach <l.stelmach@...sung.com>
>> ---
>> .../bindings/crypto/samsung,exynos-rng4.txt | 4 ++-
>> drivers/crypto/exynos-rng.c | 36 ++++++++++++++++++++--
>> 2 files changed, 36 insertions(+), 4 deletions(-)
>>
>> diff --git
>> a/Documentation/devicetree/bindings/crypto/samsung,exynos-rng4.txt
>> b/Documentation/devicetree/bindings/crypto/samsung,exynos-rng4.txt
>> index 4ca8dd4d7e66..a13fbdb4bd88 100644
>> --- a/Documentation/devicetree/bindings/crypto/samsung,exynos-rng4.txt
>> +++ b/Documentation/devicetree/bindings/crypto/samsung,exynos-rng4.txt
>> @@ -2,7 +2,9 @@ Exynos Pseudo Random Number Generator
>>
>> Required properties:
>>
>> -- compatible : Should be "samsung,exynos4-rng".
>> +- compatible : One of:
>> + - "samsung,exynos4-rng" for Exynos4210 and Exynos4412
>> + - "samsung,exynos5250-prng" for Exynos5250+
>> - reg : Specifies base physical address and size of the registers map.
>> - clocks : Phandle to clock-controller plus clock-specifier pair.
>> - clock-names : "secss" as a clock name.
>> diff --git a/drivers/crypto/exynos-rng.c b/drivers/crypto/exynos-rng.c
>> index 451620b475a0..894ef93ef5ec 100644
>> --- a/drivers/crypto/exynos-rng.c
>> +++ b/drivers/crypto/exynos-rng.c
>> @@ -22,12 +22,17 @@
>> #include <linux/err.h>
>> #include <linux/io.h>
>> #include <linux/module.h>
>> +#include <linux/of_device.h>
>> #include <linux/platform_device.h>
>>
>> #include <crypto/internal/rng.h>
>>
>> #define EXYNOS_RNG_CONTROL 0x0
>> #define EXYNOS_RNG_STATUS 0x10
>> +
>> +#define EXYNOS_RNG_SEED_CONF 0x14
>> +#define EXYNOS_RNG_GEN_PRNG 0x02
>
> Use BIT(1) instead.
>
>> +
>> #define EXYNOS_RNG_SEED_BASE 0x140
>> #define EXYNOS_RNG_SEED(n) (EXYNOS_RNG_SEED_BASE + (n * 0x4))
>> #define EXYNOS_RNG_OUT_BASE 0x160
>> @@ -43,6 +48,11 @@
>> #define EXYNOS_RNG_SEED_REGS 5
>> #define EXYNOS_RNG_SEED_SIZE (EXYNOS_RNG_SEED_REGS * 4)
>>
>> +enum exynos_prng_type {
>> + EXYNOS_PRNG_TYPE4 = 4,
>> + EXYNOS_PRNG_TYPE5 = 5,
>
> That's unusual numbering and naming, so just:
> enum exynos_prng_type {
> EXYNOS_PRNG_EXYNOS4,
> EXYNOS_PRNG_EXYNOS5,
> };
>
> Especially that TYPE4 and TYPE5 suggest so kind of sub-type (like
> versions of some IP blocks, e.g. MFC) but it is just the family of
> Exynos.
Half done. I've changed TYPE to EXYNOS.
I used explicit numbering in the enum because I want both values to act
same true-false-wise. If one is 0 this condition is not met.
>> +};
>> +
>> /*
>> * Driver re-seeds itself with generated random numbers to increase
>> * the randomness.
>> @@ -63,6 +73,7 @@ struct exynos_rng_ctx {
>> /* Device associated memory */
>> struct exynos_rng_dev {
>> struct device *dev;
>> + enum exynos_prng_type type;
>> void __iomem *mem;
>> struct clk *clk;
>> /* Generated numbers stored for seeding during resume */
>> @@ -160,8 +171,13 @@ static int exynos_rng_get_random(struct exynos_rng_dev *rng,
>> {
>> int retry = EXYNOS_RNG_WAIT_RETRIES;
>>
>> - exynos_rng_writel(rng, EXYNOS_RNG_CONTROL_START,
>> - EXYNOS_RNG_CONTROL);
>> + if (rng->type == EXYNOS_PRNG_TYPE4) {
>> + exynos_rng_writel(rng, EXYNOS_RNG_CONTROL_START,
>> + EXYNOS_RNG_CONTROL);
>> + } else if (rng->type == EXYNOS_PRNG_TYPE5) {
>> + exynos_rng_writel(rng, EXYNOS_RNG_GEN_PRNG,
>> + EXYNOS_RNG_SEED_CONF);
>> + }
>>
>> while (!(exynos_rng_readl(rng,
>> EXYNOS_RNG_STATUS) & EXYNOS_RNG_STATUS_RNG_DONE) && --retry)
>> @@ -279,6 +295,13 @@ static int exynos_rng_probe(struct platform_device *pdev)
>> if (!rng)
>> return -ENOMEM;
>>
>> + rng->type = (enum exynos_prng_type)of_device_get_match_data(&pdev->dev);
>> + if (rng->type != EXYNOS_PRNG_TYPE4 &&
>> + rng->type != EXYNOS_PRNG_TYPE5) {
>> + dev_err(&pdev->dev, "Unsupported PRNG type: %d", rng->type);
>> + return -ENOTSUPP;
>> + }
>> +
>> rng->dev = &pdev->dev;
>> rng->clk = devm_clk_get(&pdev->dev, "secss");
>> if (IS_ERR(rng->clk)) {
>> @@ -300,7 +323,10 @@ static int exynos_rng_probe(struct platform_device *pdev)
>> dev_err(&pdev->dev,
>> "Couldn't register rng crypto alg: %d\n", ret);
>> exynos_rng_dev = NULL;
>> - }
>> + } else
>
> Missing {} around else clause. Probably checkpatch should point it.
It doesn't. Fixed.
>> + dev_info(&pdev->dev,
>> + "Exynos Pseudo Random Number Generator (type:%d)\n",
>
> dev_dbg, this is not that important information to affect the boot time.
Quite many devices report their presence during boot with such
messages. For example:
[ 3.390247] exynos-ehci 12110000.usb: EHCI Host Controller
[ 3.395493] exynos-ehci 12110000.usb: new USB bus registered, assigned bus number 1
[ 3.403702] exynos-ehci 12110000.usb: irq 80, io mem 0x12110000
[ 3.431793] exynos-ehci 12110000.usb: USB 2.0 started, EHCI 1.00
From my experience it isn't printk() itself that slows down boot but the
serial console.
--
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics
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