[U-Boot] [PATCH 1/2] smbios: add parsing API

[Christian Gmeiner]

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.

>
> 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?

-- 
greets
--
Christian Gmeiner, MSc

https://christian-gmeiner.info