smbios: add parsing API

Add a very simple API to be able to access SMBIOS strings
like vendor, model and bios version.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/include/smbios.h b/include/smbios.h
index 97b9ddce23762eaabf18d36ce6241f84955ab4d5..44f49e9556bf27acf9059df6b213ffe174affb5b 100644 (file)
--- a/include/smbios.h
+++ b/include/smbios.h
@@ -237,4 +237,31 @@ typedef int (*smbios_write_type)(ulong *addr, int handle);
  */
 ulong write_smbios_table(ulong addr);
 
+/**
+ * smbios_entry() - Get a valid struct smbios_entry pointer
+ *
+ * @address:   address where smbios tables is located
+ * @size:      size of smbios table
+ * @return:    NULL or a valid pointer to a struct smbios_entry
+ */
+const struct smbios_entry *smbios_entry(u64 address, u32 size);
+
+/**
+ * smbios_header() - Search for SMBIOS header type
+ *
+ * @entry:     pointer to a struct smbios_entry
+ * @type:      SMBIOS type
+ * @return:    NULL or a valid pointer to a struct smbios_header
+ */
+const struct smbios_header *smbios_header(const struct smbios_entry *entry, 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 79651eaad199fcc4526466653f4e7f3ef53c881b..5f1b95d7d7b9ef1829293d6b338140ce475081ff 100644 (file)
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -680,6 +680,11 @@ config OID_REGISTRY
        help
          Enable fast lookup object identifier registry.
 
+config SMBIOS_PARSER
+       bool "SMBIOS parser"
+       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 7c7fb9aae78c2573caa1670445d07386fad1a63c..851a80ef3bf86c000dd7730246ac15343a590313 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -37,6 +37,7 @@ 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_XXHASH) += xxhash.o

diff --git a/lib/smbios-parser.c b/lib/smbios-parser.c
new file mode 100644 (file)
index 0000000..b89f988
--- /dev/null
+++ b/lib/smbios-parser.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020, Bachmann electronic GmbH
+ */
+
+#include <common.h>
+#include <smbios.h>
+
+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;
+}
+
+const struct smbios_entry *smbios_entry(u64 address, u32 size)
+{
+       const struct smbios_entry *entry = (struct smbios_entry *)(uintptr_t)address;
+
+       if (!address | !size)
+               return NULL;
+
+       if (memcmp(entry->anchor, "_SM_", 4))
+               return NULL;
+
+       if (verify_checksum(entry))
+               return NULL;
+
+       return entry;
+}
+
+static const struct smbios_header *next_header(const struct smbios_header *curr)
+{
+       u8 *pos = ((u8 *)curr) + curr->length;
+
+       /* search for _double_ NULL bytes */
+       while (!((*pos == 0) && (*(pos + 1) == 0)))
+               pos++;
+
+       /* step behind the double NULL bytes */
+       pos += 2;
+
+       return (struct smbios_header *)pos;
+}
+
+const struct smbios_header *smbios_header(const struct smbios_entry *entry, int type)
+{
+       const unsigned int num_header = entry->struct_count;
+       const struct smbios_header *header = (struct smbios_header *)entry->struct_table_address;
+
+       for (unsigned int i = 0; i < num_header; i++) {
+               if (header->type == type)
+                       return header;
+
+               header = next_header(header);
+       }
+
+       return NULL;
+}
+
+static const char *string_from_smbios_table(const struct smbios_header *header,
+                                           int idx)
+{
+       unsigned int i = 1;
+       u8 *pos;
+
+       if (!header)
+               return NULL;
+
+       pos = ((u8 *)header) + header->length;
+
+       while (i < idx) {
+               if (*pos == 0x0)
+                       i++;
+
+               pos++;
+       }
+
+       return (const char *)pos;
+}
+
+const char *smbios_string(const struct smbios_header *header, int index)
+{
+       if (!header)
+               return NULL;
+
+       return string_from_smbios_table(header, index);
+}