Re: [PATCH v5 4/4] crypto: Add Allwinner Security System crypto accelerator

[Vladimir Zapolskiy]

Hi Corentin,

On 21.10.2014 19:25, Corentin LABBE wrote:
> On 10/21/14 01:28, Vladimir Zapolskiy wrote:
>> Hello LABBE,
>>
>> On 19.10.2014 17:16, LABBE Corentin wrote:
>>> Add support for the Security System included in Allwinner SoC A20.
>>> The Security System is a hardware cryptographic accelerator that support AES/MD5/SHA1/DES/3DES/PRNG algorithms.
>>>
> []
>>> +
>>> +	/* If we have only one SG, we can use kmap_atomic */
>>> +	if (sg_next(in_sg) == NULL && sg_next(out_sg) == NULL)
>>> +		return sunxi_ss_aes_poll_atomic(areq);
>>
>> for clarity it might be better to move all "mutex_unlock(&ss->lock)"
>> calls from sunxi_ss_aes_poll_atomic() body right to here.
>>
> 
> Ok
> I have moved all mutex_unlock/writel(0, SS_CTL) at the end of function, it is cleaner now.

please check that sunxi_ss_aes_poll_atomic() has no more mutex_unlock()
calls inside it.

With best wishes,
Vladimir

>>> +
>>> +};
>>> +
>>> +static int sunxi_ss_probe(struct platform_device *pdev)
>>> +{
>>> +	struct resource *res;
>>> +	u32 v;
>>> +	int err;
>>> +	unsigned long cr;
>>> +	const unsigned long cr_ahb = 24 * 1000 * 1000;
>>> +	const unsigned long cr_mod = 150 * 1000 * 1000;
>>> +
>>> +	if (!pdev->dev.of_node)
>>> +		return -ENODEV;
>>> +
>>> +	ss = devm_kzalloc(&pdev->dev, sizeof(*ss), GFP_KERNEL);
>>> +	if (ss == NULL)
>>> +		return -ENOMEM;
>>
>> Why do you dynamically allocate memory for "struct sunxi_ss_ctx *ss"?
>> Since you have a single global pointer, it makes sense to declare
>> "struct sunxi_ss_ctx ss" statically instead.
>>
>> And even a better solution is to remove a single global pointer.
> 
> All other crypto driver I have read use a global structure and it made things easy.
> Thanks to M. Ripard that pointed to me the talitos driver that solve the global device pointer by using alg template and container_of().
> 
> But since I think there will never 2 Security System at the same time on the same SoC, I do not know if it is worth the cost to add more complexity just to remove a pointer.
> 
>>
>>> +
>>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> +	ss->base = devm_ioremap_resource(&pdev->dev, res);
>>> +	if (IS_ERR(ss->base)) {
>>> +		dev_err(&pdev->dev, "Cannot request MMIO\n");
>>> +		return PTR_ERR(ss->base);
>>> +	}
>>> +
>>> +	ss->ssclk = devm_clk_get(&pdev->dev, "mod");
>>> +	if (IS_ERR(ss->ssclk)) {
>>> +		err = PTR_ERR(ss->ssclk);
>>> +		dev_err(&pdev->dev, "Cannot get SS clock err=%d\n", err);
>>> +		return err;
>>> +	}
>>> +	dev_dbg(&pdev->dev, "clock ss acquired\n");
>>> +
>>> +	ss->busclk = devm_clk_get(&pdev->dev, "ahb");
>>> +	if (IS_ERR(ss->busclk)) {
>>> +		err = PTR_ERR(ss->busclk);
>>> +		dev_err(&pdev->dev, "Cannot get AHB SS clock err=%d\n", err);
>>> +		return err;
>>> +	}
>>> +	dev_dbg(&pdev->dev, "clock ahb_ss acquired\n");
>>> +
>>> +	/* Enable both clocks */
>>> +	err = clk_prepare_enable(ss->busclk);
>>> +	if (err != 0) {
>>> +		dev_err(&pdev->dev, "Cannot prepare_enable busclk\n");
>>> +		return err;
>>> +	}
>>> +	err = clk_prepare_enable(ss->ssclk);
>>> +	if (err != 0) {
>>> +		dev_err(&pdev->dev, "Cannot prepare_enable ssclk\n");
>>> +		clk_disable_unprepare(ss->busclk);
>>
>> goto somewhere to the end of the function?
> 
> OK
> 
>>
>>> +		return err;
>>> +	}
>>> +
>>> +	/*
>>> +	 * Check that clock have the correct rates gived in the datasheet
>>> +	 * Try to set the clock to the maximum allowed
>>> +	 */
>>> +	err = clk_set_rate(ss->ssclk, cr_mod);
>>> +	if (err != 0) {
>>> +		dev_err(&pdev->dev, "Cannot set clock rate to ssclk\n");
>>> +		clk_disable_unprepare(ss->ssclk);
>>> +		clk_disable_unprepare(ss->busclk);
>>
>> goto "error_md5"?
> 
> Ok
> 
>>
>>> +		return err;
>>> +	}
>>> +
>>> +	cr = clk_get_rate(ss->busclk);
>>> +	if (cr >= cr_ahb)
>>> +		dev_dbg(&pdev->dev, "Clock bus %lu (%lu MHz) (must be >= %lu)\n",
>>> +				cr, cr / 1000000, cr_ahb);
>>> +	else
>>> +		dev_warn(&pdev->dev, "Clock bus %lu (%lu MHz) (must be >= %lu)\n",
>>> +				cr, cr / 1000000, cr_ahb);
>>
>> See next comment.
>>
>>> +	cr = clk_get_rate(ss->ssclk);
>>> +	if (cr <= cr_mod)
>>> +		if (cr < cr_mod)
>>> +			dev_info(&pdev->dev, "Clock ss %lu (%lu MHz) (must be <= %lu)\n",
>>> +					cr, cr / 1000000, cr_mod);
>>> +		else
>>> +			dev_dbg(&pdev->dev, "Clock ss %lu (%lu MHz) (must be <= %lu)\n",
>>> +					cr, cr / 1000000, cr_mod);
>>> +	else
>>> +		dev_warn(&pdev->dev, "Clock ss is at %lu (%lu MHz) (must be <= %lu)\n",
>>> +				cr, cr / 1000000, cr_mod);
>>
>> The management of kernel log levels looks pretty strange. As far as I
>> understand there is no error on any clock rate, I'd recommend to keep
>> only one information message.
>>
> 
> If clock rate are below the recommended value, the only impact I found was bad performance.
> So it explain the warn and no error. (yes the info must be warn, ...fixed)
> 
> But I will put comment for explain that.
> 
>>> +	/*
>>> +	 * Datasheet named it "Die Bonding ID"
>>> +	 * I expect to be a sort of Security System Revision number.
>>> +	 * Since the A80 seems to have an other version of SS
>>> +	 * this info could be useful
>>> +	 */
>>> +	writel(SS_ENABLED, ss->base + SS_CTL);
>>> +	v = readl(ss->base + SS_CTL);
>>> +	v >>= 16;
>>> +	v &= 0x07;
>>> +	dev_info(&pdev->dev, "Die ID %d\n", v);
>>> +	writel(0, ss->base + SS_CTL);
>>> +
>>> +	ss->dev = &pdev->dev;
>>> +
>>> +	mutex_init(&ss->lock);
>>> +	mutex_init(&ss->bufin_lock);
>>> +	mutex_init(&ss->bufout_lock);
>>> +
>>> +	err = crypto_register_ahash(&sunxi_md5_alg);
>>> +	if (err)
>>> +		goto error_md5;
>>> +	err = crypto_register_ahash(&sunxi_sha1_alg);
>>> +	if (err)
>>> +		goto error_sha1;
>>> +	err = crypto_register_algs(sunxi_cipher_algs,
>>> +			ARRAY_SIZE(sunxi_cipher_algs));
>>> +	if (err)
>>> +		goto error_ciphers;
>>> +
>>> +	return 0;
>>> +error_ciphers:
>>> +	crypto_unregister_ahash(&sunxi_sha1_alg);
>>> +error_sha1:
>>> +	crypto_unregister_ahash(&sunxi_md5_alg);
>>> +error_md5:
>>> +	clk_disable_unprepare(ss->ssclk);
>>> +	clk_disable_unprepare(ss->busclk);
>>> +	return err;
>>> +}
>>> +
>>> +static int __exit sunxi_ss_remove(struct platform_device *pdev)
>>> +{
>>> +	if (!pdev->dev.of_node)
>>> +		return 0;
>>
>> Redundant check.
>>
> 
> Ok
> 
>>
>>
>> --
>> With best wishes,
>> Vladimir
>>
> 
> Thanks for the review
> 
> 
> 
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> 
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