Re: [PATCH v2 05/15] pbl: fdt: add pbl_load_fdt helper

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

On 2/4/26 9:01 PM, Marco Felsch wrote:
> The helper provides a common FDT load mechanism to load the (optional
> compressed) DTB to the provided destination address in a user agnostic
> manner.
> 
> Early FDTs may be useful for other firmware binaries like TEEs (e.g.
> OP-TEE) which are loaded and started during the barebox boot phase.
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>

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

> ---
>  include/pbl.h |  2 ++
>  pbl/fdt.c     | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 81 insertions(+)
> 
> diff --git a/include/pbl.h b/include/pbl.h
> index 14a463ef8a9f18e42a3332889ca8d9b30d8f1ceb..514f1143706785946e4190f23f95422f23df42e3 100644
> --- a/include/pbl.h
> +++ b/include/pbl.h
> @@ -31,6 +31,8 @@ fdt_device_get_match_data(const void *fdt, const char *nodepath,
>  
>  int pbl_barebox_verify(const void *compressed_start, unsigned int len,
>  		       const void *hash, unsigned int hash_len);
> +int pbl_load_fdt(const void *fdt, void *dest, int destsize);
> +
>  #endif
>  
>  void __noreturn barebox_pbl_entry(ulong, ulong, void *);
> diff --git a/pbl/fdt.c b/pbl/fdt.c
> index ac377446caeafb1beaeb211aa8bdec8767ae21fe..3c90959f8e73ea7310248f9b31359d6e8a86ae57 100644
> --- a/pbl/fdt.c
> +++ b/pbl/fdt.c
> @@ -1,8 +1,10 @@
>  // SPDX-License-Identifier: GPL-2.0
> +#include <compressed-dtb.h>
>  #include <linux/libfdt.h>
>  #include <pbl.h>
>  #include <linux/printk.h>
>  #include <stdio.h>
> +#include <uncompress.h>
>  
>  static const __be32 *fdt_parse_reg(const __be32 *reg, uint32_t n,
>  				   uint64_t *val)
> @@ -185,3 +187,80 @@ const void *fdt_device_get_match_data(const void *fdt, const char *nodepath,
>  
>  	return NULL;
>  }
> +
> +static int pbl_open_dtbz_into(const void *fdt, void *buf, int bufsize)
> +{
> +	const struct barebox_boarddata_compressed_dtb *compressed_dtb;
> +	int error;
> +
> +	if (!fdt_blob_can_be_decompressed(fdt)) {
> +		pr_warn("DTB can't be decompressed\n");
> +		return -EINVAL;
> +	}
> +
> +	compressed_dtb = fdt;
> +
> +	if (IS_ENABLED(CONFIG_IMAGE_COMPRESSION_NONE)) {
> +		error = fdt_open_into(compressed_dtb->data, buf, bufsize);
> +		if (error) {
> +			pr_warn("Failed to open uncompressed DTB with %s\n",
> +				fdt_strerror(error));
> +			return -EINVAL;
> +		}
> +		return 0;
> +	}
> +
> +	if (bufsize < compressed_dtb->datalen_uncompressed) {
> +		pr_warn("FDT buffer to small, min. %u bytes required\n",
> +			compressed_dtb->datalen_uncompressed);
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * No error handling required, since this will hang() if uncompress
> +	 * fails.
> +	 */
> +	pbl_dtbz_uncompress(buf, (void *)compressed_dtb->data,
> +			    compressed_dtb->datalen);
> +
> +	if (!blob_is_fdt(buf)) {
> +		pr_warn("Failed to determine FDT type for uncompressed DTB\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Required to setup size data structures to allow runtime adaptions */
> +	error = fdt_open_into(buf, buf, bufsize);
> +	if (error) {
> +		pr_warn("Failed to open decompressed DTB with %s\n",
> +			fdt_strerror(error));
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +int pbl_load_fdt(const void *fdt, void *dest, int destsize)
> +{
> +	if (destsize == 0 || !dest || !fdt) {
> +		pr_warn("Skip early FDT load, invalid input\n");
> +		return -EINVAL;
> +	}
> +
> +	if (blob_is_fdt(fdt)) {
> +		int error;
> +
> +		error = fdt_open_into(fdt, dest, destsize);
> +		if (error) {
> +			pr_warn("Failed to uncompressed DTB with %s\n",
> +				fdt_strerror(error));
> +			return -EINVAL;
> +		}
> +		return 0;
> +	} else if (blob_is_compressed_fdt(fdt)) {
> +		return pbl_open_dtbz_into(fdt, dest, destsize);
> +	}
> +
> +	pr_warn("FDT detection failed\n");
> +
> +	return -EINVAL;
> +}
> 

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |