[PATCH v3 6/6] crypto/fsl: add RNG support

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 6/25/20 2:19 PM, Michael Walle wrote:
> Register the random number generator with the rng subsystem in u-boot.
> This way it can be used by EFI as well as for the 'rng' command.
>
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
>  drivers/crypto/fsl/Kconfig   | 14 ++++++
>  drivers/crypto/fsl/Makefile  |  1 +
>  drivers/crypto/fsl/jobdesc.c | 10 +++++
>  drivers/crypto/fsl/jobdesc.h |  3 ++
>  drivers/crypto/fsl/jr.c      |  9 ++++
>  drivers/crypto/fsl/rng.c     | 86 ++++++++++++++++++++++++++++++++++++
>  6 files changed, 123 insertions(+)
>  create mode 100644 drivers/crypto/fsl/rng.c
>
> diff --git a/drivers/crypto/fsl/Kconfig b/drivers/crypto/fsl/Kconfig
> index 181a1e5e99..5ed6140da3 100644
> --- a/drivers/crypto/fsl/Kconfig
> +++ b/drivers/crypto/fsl/Kconfig
> @@ -45,3 +45,17 @@ config SYS_FSL_SEC_COMPAT
>
>  config SYS_FSL_SEC_LE
>  	bool "Little-endian access to Freescale Secure Boot"
> +
> +if FSL_CAAM
> +
> +config FSL_CAAM_RNG
> +	bool "Enable Random Number Generator support"
> +	depends on DM_RNG
> +	default y
> +	help
> +	  Enable support for the hardware based random number generator
> +	  module of the CAAM. The random data is fetched from the DRGB
> +	  using the prediction resistance flag which means the DRGB is
> +	  reseeded from the TRNG every time random data is generated.
> +
> +endif
> diff --git a/drivers/crypto/fsl/Makefile b/drivers/crypto/fsl/Makefile
> index cfb36f3bb9..a5e8d38e38 100644
> --- a/drivers/crypto/fsl/Makefile
> +++ b/drivers/crypto/fsl/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_FSL_CAAM) += jr.o fsl_hash.o jobdesc.o error.o
>  obj-$(CONFIG_CMD_BLOB) += fsl_blob.o
>  obj-$(CONFIG_CMD_DEKBLOB) += fsl_blob.o
>  obj-$(CONFIG_RSA_FREESCALE_EXP) += fsl_rsa.o
> +obj-$(CONFIG_FSL_CAAM_RNG) += rng.o
> diff --git a/drivers/crypto/fsl/jobdesc.c b/drivers/crypto/fsl/jobdesc.c
> index d9554c550b..decde64078 100644
> --- a/drivers/crypto/fsl/jobdesc.c
> +++ b/drivers/crypto/fsl/jobdesc.c
> @@ -296,6 +296,16 @@ void inline_cnstr_jobdesc_rng_deinstantiation(u32 *desc, int handle)
>  			 (handle << OP_ALG_AAI_SHIFT) | OP_ALG_AS_INITFINAL);
>  }
>
> +void inline_cnstr_jobdesc_rng(u32 *desc, void *data_out, u32 size)
> +{
> +	dma_addr_t dma_data_out = virt_to_phys(data_out);
> +
> +	init_job_desc(desc, 0);
> +	append_operation(desc, OP_ALG_ALGSEL_RNG | OP_TYPE_CLASS1_ALG |
> +			 OP_ALG_PR_ON);
> +	append_fifo_store(desc, dma_data_out, size, FIFOST_TYPE_RNGSTORE);
> +}
> +
>  /* Change key size to bytes form bits in calling function*/
>  void inline_cnstr_jobdesc_pkha_rsaexp(uint32_t *desc,
>  				      struct pk_in_params *pkin, uint8_t *out,
> diff --git a/drivers/crypto/fsl/jobdesc.h b/drivers/crypto/fsl/jobdesc.h
> index 5185ddd535..c4501abd26 100644
> --- a/drivers/crypto/fsl/jobdesc.h
> +++ b/drivers/crypto/fsl/jobdesc.h
> @@ -43,7 +43,10 @@ void inline_cnstr_jobdesc_rng_instantiation(u32 *desc, int handle, int do_sk);
>
>  void inline_cnstr_jobdesc_rng_deinstantiation(u32 *desc, int handle);
>
> +void inline_cnstr_jobdesc_rng(u32 *desc, void *data_out, u32 size);
> +
>  void inline_cnstr_jobdesc_pkha_rsaexp(uint32_t *desc,
>  				      struct pk_in_params *pkin, uint8_t *out,
>  				      uint32_t out_siz);
> +
>  #endif
> diff --git a/drivers/crypto/fsl/jr.c b/drivers/crypto/fsl/jr.c
> index 00a3244b18..9ada1d625b 100644
> --- a/drivers/crypto/fsl/jr.c
> +++ b/drivers/crypto/fsl/jr.c
> @@ -20,6 +20,7 @@
>  #include <asm/cache.h>
>  #include <asm/fsl_pamu.h>
>  #endif
> +#include <dm/lists.h>
>
>  #define CIRC_CNT(head, tail, size)	(((head) - (tail)) & (size - 1))
>  #define CIRC_SPACE(head, tail, size)	CIRC_CNT((tail), (head) + 1, (size))
> @@ -721,6 +722,14 @@ int sec_init_idx(uint8_t sec_idx)
>  			printf("SEC%u:  RNG instantiation failed\n", sec_idx);
>  			return -1;
>  		}
> +
> +		if (IS_ENABLED(CONFIG_DM_RNG)) {
> +			ret = device_bind_driver(NULL, "caam-rng", "caam-rng",
> +						 NULL);
> +			if (ret)
> +				printf("Couldn't bind rng driver (%d)\n", ret);
> +		}
> +
>  		printf("SEC%u:  RNG instantiated\n", sec_idx);
>  	}
>  #endif
> diff --git a/drivers/crypto/fsl/rng.c b/drivers/crypto/fsl/rng.c
> new file mode 100644
> index 0000000000..136b2cdcd7
> --- /dev/null
> +++ b/drivers/crypto/fsl/rng.c
> @@ -0,0 +1,86 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2020 Michael Walle <michael@walle.cc>
> + *
> + * Driver for Freescale Cryptographic Accelerator and Assurance
> + * Module (CAAM) hardware random number generator.
> + */
> +
> +#include <asm/cache.h>
> +#include <common.h>
> +#include <cpu_func.h>
> +#include <dm.h>
> +#include <rng.h>
> +#include "desc_constr.h"
> +#include "jobdesc.h"
> +#include "jr.h"
> +
> +#define CAAM_RNG_MAX_FIFO_STORE_SIZE 16
> +#define CAAM_RNG_DESC_LEN (3 * CAAM_CMD_SZ + CAAM_PTR_SZ)
> +
> +struct caam_rng_platdata {
> +	u32 desc[CAAM_RNG_DESC_LEN / 4];
> +	u8 data[CAAM_RNG_MAX_FIFO_STORE_SIZE] __aligned(ARCH_DMA_MINALIGN);
> +};
> +
> +static int caam_rng_read_one(struct caam_rng_platdata *pdata)
> +{
> +	int size = CAAM_RNG_MAX_FIFO_STORE_SIZE;

This should be

int size = ALIGN(CAAM_RNG_MAX_FIFO_STORE_SIZE, ARCH_DMA_MINALIGN);



> +	int ret;
> +
> +	ret = run_descriptor_jr(pdata->desc);
> +	if (ret < 0)
> +		return -EIO;
> +
> +	invalidate_dcache_range((unsigned long)pdata->data,
> +				(unsigned long)pdata->data + size);

This fails on the i.MX6 Wandboard with

CACHE: Misaligned operation at range [8e596f68, 8e596f78]

because pdata is not ARCH_DMA_MINALIGN aligned.

> +
> +	return 0;
> +}
> +
> +static int caam_rng_read(struct udevice *dev, void *data, size_t len)
> +{
> +	struct caam_rng_platdata *pdata = dev_get_platdata(dev);
> +	u8 *buffer = data;
> +	size_t size;
> +	int ret;
> +
> +	while (len) {
> +		ret = caam_rng_read_one(pdata);
> +		if (ret)
> +			return ret;
> +
> +		size = min(len, (size_t)CAAM_RNG_MAX_FIFO_STORE_SIZE);
> +
> +		memcpy(buffer, pdata->data, size);
> +		buffer += size;
> +		len -= size;
> +	}
> +
> +	return 0;
> +}
> +
> +static int caam_rng_probe(struct udevice *dev)
> +{
> +	struct caam_rng_platdata *pdata = dev_get_platdata(dev);
> +
> +	inline_cnstr_jobdesc_rng(pdata->desc, pdata->data,
> +				 CAAM_RNG_MAX_FIFO_STORE_SIZE);
> +	flush_dcache_range((unsigned long)pdata->desc,
> +			   (unsigned long)pdata->desc + CAAM_RNG_DESC_LEN);

You should round CAAM_RNG_DESC_LEN up to a multiple of ARCH_DMA_MINALIGN.

> +
> +	return 0;
> +}
> +
> +static const struct dm_rng_ops caam_rng_ops = {
> +	.read = caam_rng_read,
> +};
> +
> +U_BOOT_DRIVER(caam_rng) = {
> +	.name = "caam-rng",
> +	.id = UCLASS_RNG,
> +	.ops = &caam_rng_ops,
> +	.probe = caam_rng_probe,
> +	.platdata_auto_alloc_size = sizeof(struct caam_rng_platdata),
> +	.flags = DM_FLAG_ALLOC_PRIV_DMA,

This flag is for private data. It does not provide aligned platform data.

So you should use:

.priv_auto_alloc_size = sizeof(struct caam_rng_platdata),

and

struct caam_rng_priv *priv = dev_get_priv(dev)

Best regards

Heinrich

> +};
>