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

[Christian Gmeiner]

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) {
+		if (memcmp(sm_sig, buf, 4) == 0) {
+			entry = (struct smbios_entry *)buf;
+
+			if (verify_checksum(entry)) {
+				entry = NULL;
+				buf++;
+				continue;
+			}
+
+			break;
+		}
+
+		buf++;
+	}
+
+	return entry;
+}
+
+void smbios_parser_destroy(struct smbios_parser *p)
+{
+	if (!p)
+		return;
+
+	unmap_sysmem(p->data);
+	unmap_sysmem(p->search_area);
+
+	free(p);
+}
+
+struct smbios_parser *smbios_parser_create(unsigned int addr, unsigned int len)
+{
+	struct smbios_parser *p = malloc(sizeof(struct smbios_parser));
+
+	if (!p)
+		return NULL;
+
+	p->search_area_len = len;
+	p->search_area = map_sysmem(addr, len);
+
+	if (!p->search_area)
+		goto fail;
+
+	/* find main entry smbios table */
+	p->entry = find_smbios_entry(p);
+
+	if (!p->entry)
+		goto fail;
+
+	/* map smbios data area */
+	p->data = map_sysmem(p->entry->struct_table_address,
+			     p->entry->struct_table_length);
+
+	if (!p->data)
+		goto fail;
+
+	return p;
+
+fail:
+	smbios_parser_destroy(p);
+
+	return NULL;
+}
+
+static 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;
+}
+
+struct smbios_header *smbios_header(const struct smbios_parser *p, int type)
+{
+	const struct smbios_entry *entry = p->entry;
+	const unsigned int num_header = entry->struct_count;
+	struct smbios_header *header = (struct smbios_header *)p->data;
+
+	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);
+}
-- 
2.20.1