[PATCH 09/23] pbl: fdt: add pbl_load_fdt helper
Ahmad Fatoum
a.fatoum at pengutronix.de
Thu Jan 22 06:16:11 PST 2026
Hello Marco,
On 1/18/26 8:18 PM, Marco Felsch wrote:
> 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 at 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.
Yes, but the user visible option should be arch-specific as well.
It's ok to have a config symbol in pbl/ to reduce compile time, but it
should be promptless IMO.
Cheers,
Ahmad
>
> 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;
>>> +}
>>>
>>
>> --
>> 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 |
>>
>>
>
--
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 |
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