[PATCH] crypto: caam - skip RNG selftest when i.MX6 is in normal world

[Marco Felsch]

On 25-10-29, Ahmad Fatoum wrote:
> On an i.MX6 running under OP-TEE, the CAAM selftest fails as it needs to
> run in the secure world[1].
> 
> We can detect that barebox is running in the normal world on an i.MX6,
> so use that info to gracefully skip the test.
> 
> This is not enough to get the CAAM working (The DECO registers may not
> be accessible to barebox), but that is arguably a more useful error
> message than an -EBUSY.
> 
> [1]: Scroll down to "Job Ring TZ assignment issue"
> https://community.nxp.com/t5/i-MX-Security/RNG-self-test-errors-on-select-i-MX-device-revisions/ta-p/1102970
> 
> Reported-by: Fabian Pflug <f.pflug at pengutronix.de>
> Cc: Marco Felsch <m.felsch at pengutronix.de>
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
>  arch/arm/mach-imx/imx6.c            |  2 +-
>  drivers/crypto/caam/rng_self_test.c | 13 ++++++++++++-
>  include/mach/imx/imx6.h             |  2 ++
>  3 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/imx6.c b/arch/arm/mach-imx/imx6.c
> index 0cf2c17d6b90..29a56de56293 100644
> --- a/arch/arm/mach-imx/imx6.c
> +++ b/arch/arm/mach-imx/imx6.c
> @@ -254,7 +254,7 @@ int imx6_devices_init(void)
>  	return 0;
>  }
>  
> -static bool imx6_cannot_write_l2x0(void)
> +bool imx6_cannot_write_l2x0(void)
>  {
>  	void __iomem *l2x0_base = IOMEM(0x00a02000);
>  	u32 val;
> diff --git a/drivers/crypto/caam/rng_self_test.c b/drivers/crypto/caam/rng_self_test.c
> index 5216ecef4451..a42d9cad1639 100644
> --- a/drivers/crypto/caam/rng_self_test.c
> +++ b/drivers/crypto/caam/rng_self_test.c
> @@ -47,6 +47,8 @@
>  #include <dma.h>
>  #include <common.h>
>  #include <linux/kernel.h>
> +#include <mach/imx/generic.h>
> +#include <mach/imx/imx6.h>
>  
>  #include "error.h"
>  #include "regs.h"
> @@ -143,7 +145,7 @@ static void rng_self_test_done(struct device *dev, u32 *desc, u32 err,
>   * * i.MX6DLS silicon revision 1.4
>   * * i.MX6SX silicon revision 1.4
>   * * i.MX6UL silicon revision 1.2
> - * * i.MX67SD silicon revision 1.3
> + * * i.MX7SD silicon revision 1.3
>   *
>   */
>  int caam_rng_self_test(struct device *dev, const u8 caam_era, const u8 rngvid,
> @@ -176,6 +178,15 @@ int caam_rng_self_test(struct device *dev, const u8 caam_era, const u8 rngvid,
>  		return -EINVAL;
>  	}
>  
> +	if (cpu_is_mx6() && imx6_cannot_write_l2x0()) {

Nit:
Would be nice to have an in_secure_mode() function to make the purpose
more clear. However, change is correct and you added a comment, so

Reviewed-by: Marco Felsch <m.felsch at pengutronix.de>


> +		/* If we enter this if clause, we are likely running
> +		 * under OP-TEE, so there is no point in continuing
> +		 * and getting -EBUSY waiting for job completion
> +		 */
> +		pr_info("skipping test in normal world\n");
> +		return 0;
> +	}
> +
>  	result = dma_alloc(sizeof(*result) * result_size);
>  	desc = dma_alloc(sizeof(*desc) * desc_size);
>  
> diff --git a/include/mach/imx/imx6.h b/include/mach/imx/imx6.h
> index 109df9b811c5..7b3cedd80f66 100644
> --- a/include/mach/imx/imx6.h
> +++ b/include/mach/imx/imx6.h
> @@ -135,4 +135,6 @@ int imx6_cpu_revision(void);
>  
>  u64 imx6_uid(void);
>  
> +bool imx6_cannot_write_l2x0(void);
> +
>  #endif /* __MACH_IMX6_H */
> -- 
> 2.47.3
> 
> 

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