Re: [PATCH v4 3/5] crypto: qcom-rng - Add hw_random interface support

[Om Prakash Singh <quic_omprsing@quicinc.com>]

On 10/3/2023 12:40 PM, neil.armstrong@linaro.org wrote:
> From: Om Prakash Singh <quic_omprsing@quicinc.com>
> 
> Add hw_random interface support in qcom-rng driver as new IP block
> in Qualcomm SoC has inbuilt NIST SP800 90B compliant entropic source
> to generate true random number.
> 
> Keeping current rng_alg interface as well for random number generation
> using Kernel Crypto API.
> 
> Signed-off-by: Om Prakash Singh <quic_omprsing@quicinc.com>
> Reviewed-by: Bjorn Andersson <quic_bjorande@quicinc.com>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---

Acked-by: Om Prakash Singh <quic_omprsing@quicinc.com>

>   drivers/crypto/qcom-rng.c | 65 ++++++++++++++++++++++++++++++++++++++++++-----
>   1 file changed, 58 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/crypto/qcom-rng.c b/drivers/crypto/qcom-rng.c
> index 825a729f205e..8b506abb934c 100644
> --- a/drivers/crypto/qcom-rng.c
> +++ b/drivers/crypto/qcom-rng.c
> @@ -7,6 +7,7 @@
>   #include <linux/acpi.h>
>   #include <linux/clk.h>
>   #include <linux/crypto.h>
> +#include <linux/hw_random.h>
>   #include <linux/io.h>
>   #include <linux/iopoll.h>
>   #include <linux/kernel.h>
> @@ -28,17 +29,25 @@
>   
>   #define WORD_SZ			4
>   
> +#define QCOM_TRNG_QUALITY	1024
> +
>   struct qcom_rng {
>   	struct mutex lock;
>   	void __iomem *base;
>   	struct clk *clk;
> -	unsigned int skip_init;
> +	struct hwrng hwrng;
> +	struct qcom_rng_of_data *of_data;
>   };
>   
>   struct qcom_rng_ctx {
>   	struct qcom_rng *rng;
>   };
>   
> +struct qcom_rng_of_data {
> +	bool skip_init;
> +	bool hwrng_support;
> +};
> +
>   static struct qcom_rng *qcom_rng_dev;
>   
>   static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
> @@ -66,11 +75,11 @@ static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
>   		} else {
>   			/* copy only remaining bytes */
>   			memcpy(data, &val, max - currsize);
> -			break;
> +			currsize = max;
>   		}
>   	} while (currsize < max);
>   
> -	return 0;
> +	return currsize;
>   }
>   
>   static int qcom_rng_generate(struct crypto_rng *tfm,
> @@ -92,6 +101,9 @@ static int qcom_rng_generate(struct crypto_rng *tfm,
>   	mutex_unlock(&rng->lock);
>   	clk_disable_unprepare(rng->clk);
>   
> +	if (ret >= 0)
> +		ret = 0;
> +
>   	return ret;
>   }
>   
> @@ -101,6 +113,13 @@ static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
>   	return 0;
>   }
>   
> +static int qcom_hwrng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
> +{
> +	struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng);
> +
> +	return qcom_rng_read(qrng, data, max);
> +}
> +
>   static int qcom_rng_enable(struct qcom_rng *rng)
>   {
>   	u32 val;
> @@ -136,7 +155,7 @@ static int qcom_rng_init(struct crypto_tfm *tfm)
>   
>   	ctx->rng = qcom_rng_dev;
>   
> -	if (!ctx->rng->skip_init)
> +	if (!ctx->rng->of_data->skip_init)
>   		return qcom_rng_enable(ctx->rng);
>   
>   	return 0;
> @@ -177,15 +196,31 @@ static int qcom_rng_probe(struct platform_device *pdev)
>   	if (IS_ERR(rng->clk))
>   		return PTR_ERR(rng->clk);
>   
> -	rng->skip_init = (unsigned long)device_get_match_data(&pdev->dev);
> +	rng->of_data = (struct qcom_rng_of_data *)of_device_get_match_data(&pdev->dev);
>   
>   	qcom_rng_dev = rng;
>   	ret = crypto_register_rng(&qcom_rng_alg);
>   	if (ret) {
>   		dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
>   		qcom_rng_dev = NULL;
> +		return ret;
> +	}
> +
> +	if (rng->of_data->hwrng_support) {
> +		rng->hwrng.name = "qcom_hwrng";
> +		rng->hwrng.read = qcom_hwrng_read;
> +		rng->hwrng.quality = QCOM_TRNG_QUALITY;
> +		ret = devm_hwrng_register(&pdev->dev, &rng->hwrng);
> +		if (ret) {
> +			dev_err(&pdev->dev, "Register hwrng failed: %d\n", ret);
> +			qcom_rng_dev = NULL;
> +			goto fail;
> +		}
>   	}
>   
> +	return ret;
> +fail:
> +	crypto_unregister_rng(&qcom_rng_alg);
>   	return ret;
>   }
>   
> @@ -198,6 +233,21 @@ static int qcom_rng_remove(struct platform_device *pdev)
>   	return 0;
>   }
>   
> +struct qcom_rng_of_data qcom_prng_of_data = {
> +	.skip_init = false,
> +	.hwrng_support = false,
> +};
> +
> +struct qcom_rng_of_data qcom_prng_ee_of_data = {
> +	.skip_init = true,
> +	.hwrng_support = false,
> +};
> +
> +struct qcom_rng_of_data qcom_trng_of_data = {
> +	.skip_init = true,
> +	.hwrng_support = true,
> +};
> +
>   static const struct acpi_device_id __maybe_unused qcom_rng_acpi_match[] = {
>   	{ .id = "QCOM8160", .driver_data = 1 },
>   	{}
> @@ -205,8 +255,9 @@ static const struct acpi_device_id __maybe_unused qcom_rng_acpi_match[] = {
>   MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
>   
>   static const struct of_device_id __maybe_unused qcom_rng_of_match[] = {
> -	{ .compatible = "qcom,prng", .data = (void *)0},
> -	{ .compatible = "qcom,prng-ee", .data = (void *)1},
> +	{ .compatible = "qcom,prng", .data = &qcom_prng_of_data },
> +	{ .compatible = "qcom,prng-ee", .data = &qcom_prng_ee_of_data },
> +	{ .compatible = "qcom,trng", .data = &qcom_trng_of_data },
>   	{}
>   };
>   MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
>