Add ability to read serial number from SMBIOS

src/arch/i386/firmware/pcbios/smbios.c

@@ -0,0 +1,258 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <realmode.h>
+#include <pnpbios.h>
+#include <smbios.h>
+
+/** @file
+ *
+ * System Management BIOS
+ *
+ */
+
+/** Signature for an SMBIOS structure */
+#define SMBIOS_SIGNATURE \
+        ( ( '_' << 0 ) + ( 'S' << 8 ) + ( 'M' << 16 ) + ( '_' << 24 ) )
+
+/** SMBIOS entry point */
+struct smbios_entry {
+	/** Signature
+	 *
+	 * Must be equal to SMBIOS_SIGNATURE
+	 */
+	uint32_t signature;
+	/** Checksum */
+	uint8_t checksum;
+	/** Length */
+	uint8_t length;
+	/** Major version */
+	uint8_t major;
+	/** Minor version */
+	uint8_t minor;
+	/** Maximum structure size */
+	uint16_t max;
+	/** Entry point revision */
+	uint8_t revision;
+	/** Formatted area */
+	uint8_t formatted[5];
+	/** DMI Signature */
+	uint8_t dmi_signature[5];
+	/** DMI checksum */
+	uint8_t dmi_checksum;
+	/** Structure table length */
+	uint16_t smbios_length;
+	/** Structure table address */
+	physaddr_t smbios_address;
+	/** Number of SMBIOS structures */
+	uint16_t smbios_count;
+	/** BCD revision */
+	uint8_t bcd_revision;
+} __attribute__ (( packed ));
+
+/** An SMBIOS structure */
+struct smbios {
+	/** Type */
+	uint8_t type;
+	/** Length */
+	uint8_t length;
+	/** Handle */
+	uint16_t handle;
+} __attribute__ (( packed ));
+
+struct smbios_system_information {
+	struct smbios header;
+	uint8_t manufacturer;
+	uint8_t product;
+	uint8_t version;
+	uint8_t serial;
+} __attribute__ (( packed ));
+
+/**
+ * Find SMBIOS
+ *
+ * @v emtry		SMBIOS entry point to fill in
+ * @ret rc		Return status code
+ */
+static int find_smbios_entry ( struct smbios_entry *entry ) {
+	union {
+		struct smbios_entry entry;
+		uint8_t bytes[256]; /* 256 is maximum length possible */
+	} u;
+	unsigned int offset;
+	size_t len;
+	unsigned int i;
+	uint8_t sum = 0;
+
+	/* Try to find SMBIOS */
+	for ( offset = 0 ; offset < 0x10000 ; offset += 0x10 ) {
+
+		/* Read start of header and verify signature */
+		copy_from_real ( &u.entry, BIOS_SEG, offset,
+				 sizeof ( u.entry ));
+		if ( u.entry.signature != SMBIOS_SIGNATURE )
+			continue;
+
+		/* Read whole header and verify checksum */
+		len = u.entry.length;
+		copy_from_real ( &u.bytes, BIOS_SEG, offset, len );
+		for ( i = 0 ; i < len ; i++ ) {
+			sum += u.bytes[i];
+		}
+		if ( sum != 0 ) {
+			DBG ( "SMBIOS at %04x:%04x has bad checksum %02x\n",
+			      BIOS_SEG, offset, sum );
+			continue;
+		}
+
+		/* Fill result structure */
+		DBG ( "Found SMBIOS entry point at %04x:%04x\n",
+		      BIOS_SEG, offset );
+		memcpy ( entry, &u.entry, sizeof ( *entry ) );
+		return 0;
+	}
+
+	DBG ( "No SMBIOS found\n" );
+	return -ENOENT;
+}
+
+/**
+ * Find specific structure type within SMBIOS
+ *
+ * @v entry		SMBIOS entry point
+ * @v type		Structure type
+ * @v data		SMBIOS structure buffer to fill in
+ * @ret rc		Return status code
+ *
+ * The buffer must be at least @c entry->max bytes in size.
+ */
+static int find_smbios ( struct smbios_entry *entry, unsigned int type,
+			 void *data ) {
+	struct smbios *smbios = data;
+	userptr_t smbios_address = phys_to_user ( entry->smbios_address );
+	unsigned int count = 0;
+	size_t offset = 0;
+	size_t frag_len;
+	void *end;
+
+	while ( ( offset < entry->smbios_length ) &&
+		( count < entry->smbios_count ) ) {
+		/* Read next SMBIOS structure */
+		frag_len = ( entry->smbios_length - offset );
+		if ( frag_len > entry->max )
+			frag_len = entry->max;
+		copy_from_user ( data, smbios_address, offset, frag_len );
+
+		/* Sanity protection; ensure the last two bytes of the
+		 * buffer are 0x00,0x00, just so that a terminator
+		 * exists somewhere.  Also ensure that this lies
+		 * outside the formatted area.
+		 */
+		*( ( uint16_t * ) ( data + entry->max - 2 ) ) = 0;
+		if ( smbios->length > ( entry->max - 2 ) ) {
+			DBG ( "Invalid SMBIOS structure length %zd\n",
+			      smbios->length );
+			return -ENOENT;
+		}
+
+		DBG ( "Found SMBIOS structure type %d at offset %zx\n",
+		      smbios->type, offset );
+
+		/* If this is the structure we want, return */
+		if ( smbios->type == type )
+			return 0;
+
+		/* Find end of record.  This will always exist, thanks
+		 * to our sanity check above.
+		 */
+		for ( end = ( data + smbios->length ) ;
+		      end < ( data + entry->max ) ; end++ ) {
+			if ( *( ( uint16_t * ) end ) == 0 ) {
+				end += 2;
+				break;
+			}
+		}
+
+		offset += ( end - data );
+		count++;
+	}
+
+	DBG ( "SMBIOS structure type %d not found\n", type );
+	return -ENOENT;
+}
+
+/**
+ * Find indexed string within SMBIOS structure
+ *
+ * @v data		SMBIOS structure
+ * @v index		String index
+ * @ret string		String, or NULL
+ */
+static const char * find_smbios_string ( void *data, unsigned int index ) {
+	struct smbios *smbios = data;
+	const char *string;
+	size_t len;
+
+	if ( ! index )
+		return NULL;
+
+	string = ( data + smbios->length );
+	while ( --index ) {
+		/* Move to next string */
+		len = strlen ( string );
+		if ( len == 0 ) {
+			/* Reached premature end of string table */
+			DBG ( "SMBIOS string index %d not found\n", index );
+			return NULL;
+		}
+		string += ( len + 1 );
+	}
+	return string;
+}
+
+/**
+ * Find SMBIOS serial number
+ *
+ * @v data		Buffer to fill
+ * @v len		Length of buffer
+ */
+int find_smbios_serial ( void *data, size_t len ) {
+	struct smbios_entry entry;
+	const char *string;
+	int rc;
+
+	if ( ( rc = find_smbios_entry ( &entry ) ) != 0 )
+		return rc;
+
+	char buffer[entry.max];
+	if ( ( rc = find_smbios ( &entry, 1, buffer ) ) != 0 )
+		return rc;
+
+	struct smbios_system_information *sysinfo = ( void * ) buffer;
+	string = find_smbios_string ( buffer, sysinfo->serial );
+	if ( ! string )
+		return -ENOENT;
+
+	DBG ( "Found serial number \"%s\"\n", string );
+	snprintf ( data, len, "%s", string );
+	return 0;
+}

src/arch/i386/include/smbios.h

@@ -0,0 +1,11 @@
+#ifndef _SMBIOS_H
+#define _SMBIOS_H
+
+/** @file
+ *
+ * System Management BIOS
+ */
+
+extern int find_smbios_serial ( void *data, size_t len );
+
+#endif /* _SMBIOS_H */