Re: [PATCH 09/23] pbl: fdt: add pbl_load_fdt helper

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Ahmad,

On 26-01-15, Ahmad Fatoum wrote:
> Hello Marco.
> 
> On 11/10/25 9:34 PM, Marco Felsch wrote:
> > The helper provides a common FDT load mechanism to load the (compressed)
> > DTB to the provided destination address. Early FDTs may required by
> > other BL3x binaries like BL31 (TF-A) and BL32 (OP-TEE).
> > 
> > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > ---
> >  arch/Kconfig  |  3 +++
> >  include/pbl.h |  2 ++
> >  pbl/Kconfig   | 11 +++++++++
> >  pbl/fdt.c     | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 91 insertions(+)
> > 
> > diff --git a/arch/Kconfig b/arch/Kconfig
> > index 55618bf896c25f2afa2786706e27fce6ab4b3a39..edd574879b244d3843f1b5a06e1e25c5d4acbc8d 100644
> > --- a/arch/Kconfig
> > +++ b/arch/Kconfig
> > @@ -62,6 +62,9 @@ config ARCH_DMA_DEFAULT_COHERENT
> >  config ARCH_HAS_DMA_WRITE_COMBINE
> >  	bool
> >  
> > +config ARCH_HAS_EARLY_FDT_SUPPORT
> > +	bool
> > +
> >  config ARCH_HAS_ASAN_FIBER_API
> >  	bool
> >  
> > diff --git a/include/pbl.h b/include/pbl.h
> > index 9db4652e833bf5e82fd42a1cae19e94c4f2f868f..bf0c9e2ba29428361cb16a572295e66f20acdd82 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/Kconfig b/pbl/Kconfig
> > index cab9325d16e8625bcca10125b3281062abffedbc..ea2086f33ea405ecd7b00065eaf9874218152b3a 100644
> > --- a/pbl/Kconfig
> > +++ b/pbl/Kconfig
> > @@ -65,6 +65,17 @@ config PBL_VERIFY_PIGGY
> >  	depends on ARM || MIPS || RISCV
> >  	bool "Verify barebox proper hash before decompression" if COMPILE_TEST
> >  
> > +config PBL_EARLY_FDT_LOAD
> > +	bool "Enable early FDT loading"
> > +	depends on ARCH_HAS_EARLY_FDT_SUPPORT
> > +	select LIBFDT
> > +	help
> > +	  This enables the support to decompress and load the barebox builtin DTB
> > +	  during the pbl (BL2) phase.
> > +
> > +	  This is useful for BL31 and BL32 firmwares which may use the DTB for
> > +	  device configuration.
> 
> There are ARM terms, but this is the generic pbl/Kconfig. I should the

Yes, these terms are very ARM specific. I didn't wanted to mention
OP-TEE by name since there are other TEEs as well.

> symbol here should have no prompt and instead should be selected by an
> architecture specific symbol if and only if the functionality will
> actually be used.

I don't know since in the end, this is board-specific decision made by
the system-integrator.

That beeing said, I think it shouldn't be a Kconfig symbol at all,
instead each board has to decide during runtime because this decision
influences the system-boot-time.

ARCH_HAS_EARLY_FDT_SUPPORT - is independt, this should be set by the
Platform/Arch for sure.

Regards,
  Marco


> Thanks,
> Ahmad
> 
> > +
> >  config PBL_CLOCKSOURCE
> >  	bool
> >  
> > diff --git a/pbl/fdt.c b/pbl/fdt.c
> > index ac377446caeafb1beaeb211aa8bdec8767ae21fe..0cd9f5a0f11723e9f9b6848e8553da481b92f2be 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 +187,76 @@ 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 ret;
> > +
> > +	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)) {
> > +		ret = fdt_open_into(compressed_dtb->data, buf, bufsize);
> > +		if (ret)
> > +			pr_warn("Failed to open uncompressed DTB with %s\n",
> > +				fdt_strerror(ret));
> > +		return ret ? -EINVAL : 0;
> > +	}
> > +
> > +	if (bufsize < compressed_dtb->datalen_uncompressed) {
> > +		pr_warn("FDT buffer to small, min. %u bytes required\n",
> > +			compressed_dtb->datalen_uncompressed);
> > +		return -EINVAL;
> > +	}
> > +
> > +	ret = pbl_dtbz_uncompress(buf, (void *)compressed_dtb->data,
> > +				  compressed_dtb->datalen);
> > +	if (ret) {
> > +		pr_warn("Failed to uncompress DTB err=%d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	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 */
> > +	ret = fdt_open_into(buf, buf, bufsize);
> > +	if (ret)
> > +		pr_warn("Failed to open decompressed DTB with %s\n", fdt_strerror(ret));
> > +
> > +	return ret ? -EINVAL : 0;
> > +}
> > +
> > +int pbl_load_fdt(const void *fdt, void *dest, int destsize)
> > +{
> > +	int ret;
> > +
> > +	if (!IS_ENABLED(CONFIG_PBL_EARLY_FDT_LOAD))
> > +		return -ENOTSUPP;
> > +
> > +	if (destsize == 0) {
> > +		pr_warn("Skip early FDT load due to dest buffer size of 0-bytes\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (blob_is_fdt(fdt)) {
> > +		ret = fdt_open_into(fdt, dest, destsize);
> > +		if (ret)
> > +			pr_warn("Failed to uncompressed DTB with %s\n",
> > +				fdt_strerror(ret));
> > +		return ret ? -EINVAL : 0;
> > +	} else if (blob_is_compressed_fdt(fdt)) {
> > +		return pbl_open_dtbz_into(fdt, dest, destsize);
> > +	}
> > +
> > +	pr_warn("FDT detection failed\n");
> > +
> > +	return -EINVAL;
> > +}
> > 
> 
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> 

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