Re: [PATCH v2 13/15] ARM: i.MX8M: Pass optional OP-TEE overlay to barebox

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 2/4/26 9:01 PM, Marco Felsch wrote:
> This commit adds the support to pass the optional OP-TEE overlay from
> pbl to barebox for all i.MX8M SoCs.
> 
> There is no difference between ARMv7 and ARMv8, therefore the helper
> name to pass the overlay is generic.
> 
> That being said, on ARMv8 it's required to use the
> ARCH_IMX_ATF_PASS_BL_PARAMS mechanism, else the devicetree location
> can't be passed to OP-TEE. Therefore a sanity check for ARMv8 is added.
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> ---
>  arch/arm/mach-imx/esdctl.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/arch/arm/mach-imx/esdctl.c b/arch/arm/mach-imx/esdctl.c
> index e4b4ca561094e2dac99f475b93efc8fc7e962d9e..abd2cb29f01f19b19e9285b513fc289a3fa60305 100644
> --- a/arch/arm/mach-imx/esdctl.c
> +++ b/arch/arm/mach-imx/esdctl.c
> @@ -877,6 +877,45 @@ upper_or_coalesced_range(unsigned long base0, unsigned long size0,
>  	}
>  }
>  
> +static void imx_optee_handoff_overlay(void)
> +{
> +	unsigned int early_fdt_sz;
> +	u8 *early_fdt;
> +
> +	/*
> +	 * On ARMv8 i.MX SoCs CONFIG_ARCH_IMX_ATF_PASS_BL_PARAMS must be enabled
> +	 * else no FDT is passed to OP-TEE.
> +	 */
> +	if (IS_ENABLED(CONFIG_CPU_V8) &&
> +	    !IS_ENABLED(CONFIG_ARCH_IMX_ATF_PASS_BL_PARAMS))
> +		return;
> +
> +	early_fdt = imx_scratch_get_fdt(&early_fdt_sz);
> +	if (IS_ERR(early_fdt)) {
> +		pr_warn("Failed to get FDT scratch mem, skip register OP-TEE DTBO\n");
> +		return;
> +	}
> +
> +	/* SCRATCH_FDT_SIZE == 0 if no early FDT was required */
> +	if (!early_fdt)
> +		return;
> +
> +	/*
> +	 * OP-TEE DT handling is really cumbersome. In case an external DT was
> +	 * supplied, OP-TEE re-use this DT and appends overlays if enabled.
> +	 *
> +	 * Register the whole early FDT as overlay and let the barebox common
> +	 * code extract the __fragment__'s from the early FDT which should be
> +	 * faster than doing it here manually via libfdt and no MMU.
> +	 *
> +	 * Note: This assumes that OP-TEE is the only one adding __fragment__'s.
> +	 * This is always the case on ARMv7, but on ARMv8 the BL31 (TF-A) could
> +	 * add __fragment__'s too. Since the barebox i.MX port doesn't pass the
> +	 * FDT to the TF-A this is fine for now.
> +	 */
> +	optee_handoff_overlay(early_fdt, early_fdt_sz);
> +}
> +
>  void __noreturn imx1_barebox_entry(void *boarddata)
>  {
>  	unsigned long base, size;
> @@ -1020,6 +1059,7 @@ static void __noreturn imx8m_barebox_entry(void *boarddata, unsigned buswidth)
>  {
>  	imx8m_init_scratch_space(buswidth, false);
>  	optee_set_membase(imx_scratch_get_optee_hdr());
> +	imx_optee_handoff_overlay();
>  	barebox_arm_entry(MX8M_DDR_CSD1_BASE_ADDR,
>  			  imx8m_barebox_earlymem_size(buswidth), boarddata);
>  }
> 

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