[U-Boot] [PATCH 1/2] smbios: add parsing API
Christian Gmeiner
christian.gmeiner at gmail.com
Mon Apr 29 15:52:59 UTC 2019
Am Mo., 29. Apr. 2019 um 17:35 Uhr schrieb Alexander Graf <agraf at csgraf.de>:
>
>
> On 29.04.19 16:29, Christian Gmeiner wrote:
> > Hi
> >
> > Am Do., 25. Apr. 2019 um 12:09 Uhr schrieb Alexander Graf <agraf at csgraf.de>:
> >>
> >> On 16.04.19 13:38, Christian Gmeiner wrote:
> >>> Add an very simple API to be able to access SMBIOS strings
> >>> like vendor, model and bios version.
> >>>
> >>> Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
> >>> ---
> >>> include/smbios.h | 37 ++++++++++
> >>> lib/Kconfig | 6 ++
> >>> lib/Makefile | 1 +
> >>> lib/smbios-parser.c | 162 ++++++++++++++++++++++++++++++++++++++++++++
> >>> 4 files changed, 206 insertions(+)
> >>> create mode 100644 lib/smbios-parser.c
> >>>
> >>> diff --git a/include/smbios.h b/include/smbios.h
> >>> index 97b9ddce23..ad44e54245 100644
> >>> --- a/include/smbios.h
> >>> +++ b/include/smbios.h
> >>> @@ -237,4 +237,41 @@ typedef int (*smbios_write_type)(ulong *addr, int handle);
> >>> */
> >>> ulong write_smbios_table(ulong addr);
> >>>
> >>> +
> >>> +struct smbios_parser;
> >>> +
> >>> +/**
> >>> + * smbios_parser_create() - Create smbios parser
> >>> + *
> >>> + * @addr: start address to search for SMBIOS structure
> >>> + * @len: size of search area
> >>> + * @return: NULL or valid pointer to a struct smbios_parser
> >>> + */
> >>> +struct smbios_parser *smbios_parser_create(unsigned int addr, unsigned int len);
> >>> +
> >>> +/**
> >>> + * smbios_parser_destroy() - Destroy smbios parser
> >>> + *
> >>> + * @p: pointer to a struct smbios_parser
> >>> + */
> >>> +void smbios_parser_destroy(struct smbios_parser *p);
> >>> +
> >>> +/**
> >>> + * smbios_header() - Search for SMBIOS header type
> >>> + *
> >>> + * @p: pointer to a struct smbios_parser
> >>> + * @type: SMBIOS type
> >>> + * @return: NULL or a valid pointer to a struct smbios_header
> >>> + */
> >>> +struct smbios_header *smbios_header(const struct smbios_parser *p, int type);
> >>> +
> >>> +/**
> >>> + * smbios_string() - Return string from SMBIOS
> >>> + *
> >>> + * @header: pointer to struct smbios_header
> >>> + * @index: string index
> >>> + * @return: NULL or a valid const char pointer
> >>> + */
> >>> +const char *smbios_string(const struct smbios_header *header, int index);
> >>> +
> >>> #endif /* _SMBIOS_H_ */
> >>> diff --git a/lib/Kconfig b/lib/Kconfig
> >>> index 2120216593..59aafc63a7 100644
> >>> --- a/lib/Kconfig
> >>> +++ b/lib/Kconfig
> >>> @@ -432,6 +432,12 @@ config SMBIOS_PRODUCT_NAME
> >>>
> >>> endmenu
> >>>
> >>> +config SMBIOS_PARSER
> >>> + bool "SMBIOS parser"
> >>> + default n
> >>> + help
> >>> + A simple parser for SMBIOS data.
> >>> +
> >>> source lib/efi/Kconfig
> >>> source lib/efi_loader/Kconfig
> >>> source lib/optee/Kconfig
> >>> diff --git a/lib/Makefile b/lib/Makefile
> >>> index 47829bfed5..f095bd420a 100644
> >>> --- a/lib/Makefile
> >>> +++ b/lib/Makefile
> >>> @@ -34,6 +34,7 @@ obj-$(CONFIG_FIT) += fdtdec_common.o
> >>> obj-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o
> >>> obj-$(CONFIG_GZIP_COMPRESSED) += gzip.o
> >>> obj-$(CONFIG_GENERATE_SMBIOS_TABLE) += smbios.o
> >>> +obj-$(CONFIG_SMBIOS_PARSER) += smbios-parser.o
> >>> obj-$(CONFIG_IMAGE_SPARSE) += image-sparse.o
> >>> obj-y += ldiv.o
> >>> obj-$(CONFIG_MD5) += md5.o
> >>> diff --git a/lib/smbios-parser.c b/lib/smbios-parser.c
> >>> new file mode 100644
> >>> index 0000000000..b24fd7210c
> >>> --- /dev/null
> >>> +++ b/lib/smbios-parser.c
> >>> @@ -0,0 +1,162 @@
> >>> +// SPDX-License-Identifier: GPL-2.0+
> >>> +/*
> >>> + * Copyright (C) 2019, Bachmann electronic GmbH
> >>> + */
> >>> +
> >>> +#include <common.h>
> >>> +#include <malloc.h>
> >>> +#include <mapmem.h>
> >>> +#include <smbios.h>
> >>> +
> >>> +struct smbios_parser {
> >>> + void *search_area;
> >>> + unsigned int search_area_len;
> >>> + struct smbios_entry *entry;
> >>> + void *data;
> >>> +};
> >>> +
> >>> +static inline int verify_checksum(const struct smbios_entry *e)
> >>> +{
> >>> + /*
> >>> + * Checksums for SMBIOS tables are calculated to have a value, so that
> >>> + * the sum over all bytes yields zero (using unsigned 8 bit arithmetic).
> >>> + */
> >>> + u8 *byte = (u8 *)e;
> >>> + u8 sum = 0;
> >>> +
> >>> + for (int i = 0; i < e->length; i++)
> >>> + sum += byte[i];
> >>> +
> >>> + return sum;
> >>> +}
> >>> +
> >>> +static struct smbios_entry *find_smbios_entry(const struct smbios_parser *p)
> >>> +{
> >>> + static const char sm_sig[] = "_SM_";
> >>> + u8 *buf = (u8 *)p->search_area;
> >>> + const u8 *end = (u8 *)p->search_area + p->search_area_len;
> >>> + struct smbios_entry *entry = NULL;
> >>> +
> >>> + /* look for smbios entry */
> >>> + while (buf < end) {
> >>
> >> Don't you have a way to pass the DMI pointer directly, maybe using cbfs?
> >> Searching through the SMBIOS search area is so 1990s (and pretty much
> >> only works on x86).
> >>
> > Coreboot adds a smbios cbmem entry which can be used to get the base address.
> > Will make use of that mechanism in the next version of the patch set.
>
>
> Thanks, that will make this code a lot more robust :).
>
>
> >
> >> I also don't think we really need all the smbios_parser logic. No need
> >> to create special pseudo objects. IMHO you should either create an
> >> actual UCLASS for SMBIOS with genuine callbacks and expose the table as
> >> DM object or just make all search functions in this patch stateless. I'd
> >> opt for the latter - it's how the SMBIOS creation works too.
> >>
> > I am not sure what you mean with 'special pseudo objects' - struct
> > smbios_parser?
>
>
> Yes. The parser is stateful. I would ideally like it best if it wasn't :).
>
One of the reasons I need the smbios_parser is the map_sysmem(..)
thing. Maybe I do not
need it at all - that would make the whole thing much simpler.
--
greets
--
Christian Gmeiner, MSc
https://christian-gmeiner.info
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