smbios: Fix SMBIOS tables

Commit e4f8e54("smbios: Drop the unused Kconfig options")
break SMBIOS tables.  The reason is that the patch drops the Kconfig
options *after* removing the code using them,  but that changes the semantics
of the code completely.  Prior to the change a non NULL value was used in
the 'product' and 'manufacturer ' fields.

Chapter 6.2 of the DMTF spec requires Manufacturer and Product Name to be
non-null on some of the tables. So let's add sane defaults for Type1/2/3.

* Before the patchset:

<snip>
Handle 0x0002, DMI type 2, 14 bytes
Base Board Information
        Manufacturer: Not Specified
        Product Name: Not Specified
        Version: Not Specified
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Features:
                Board is a hosting board
        Location In Chassis: Not Specified
        Chassis Handle: 0x0000
        Type: Motherboard

Invalid entry length (0). DMI table is broken! Stop.

* After the patchset:

<snip>
Handle 0x0005, DMI type 32, 11 bytes
System Boot Information
        Status: No errors detected

Handle 0x0006, DMI type 127, 4 bytes
End Of Table

Fixes: e4f8e54 ("smbios: Drop the unused Kconfig options")
Signed-off-by: Ilias Apalodimas <[email protected]>

lib/smbios.c

@@ -258,7 +258,11 @@ static int smbios_write_type1(ulong *current, int handle,
 	fill_smbios_header(t, SMBIOS_SYSTEM_INFORMATION, len, handle);
 	smbios_set_eos(ctx, t->eos);
 	t->manufacturer = smbios_add_prop(ctx, "manufacturer");
+	if (!t->manufacturer)
+		t->manufacturer = smbios_add_string(ctx, "Unknown");
 	t->product_name = smbios_add_prop(ctx, "product");
+	if (!t->product_name)
+		t->product_name = smbios_add_string(ctx, "Unknown Product");
 	t->version = smbios_add_prop_si(ctx, "version",
 					SYSINFO_ID_SMBIOS_SYSTEM_VERSION);
 	if (serial_str) {
@@ -288,7 +292,11 @@ static int smbios_write_type2(ulong *current, int handle,
 	fill_smbios_header(t, SMBIOS_BOARD_INFORMATION, len, handle);
 	smbios_set_eos(ctx, t->eos);
 	t->manufacturer = smbios_add_prop(ctx, "manufacturer");
+	if (!t->manufacturer)
+		t->manufacturer = smbios_add_string(ctx, "Unknown");
 	t->product_name = smbios_add_prop(ctx, "product");
+	if (!t->product_name)
+		t->product_name = smbios_add_string(ctx, "Unknown Product");
 	t->version = smbios_add_prop_si(ctx, "version",
 					SYSINFO_ID_SMBIOS_BASEBOARD_VERSION);
 	t->asset_tag_number = smbios_add_prop(ctx, "asset-tag");
@@ -313,6 +321,8 @@ static int smbios_write_type3(ulong *current, int handle,
 	fill_smbios_header(t, SMBIOS_SYSTEM_ENCLOSURE, len, handle);
 	smbios_set_eos(ctx, t->eos);
 	t->manufacturer = smbios_add_prop(ctx, "manufacturer");
+	if (!t->manufacturer)
+		t->manufacturer = smbios_add_string(ctx, "Unknown");
 	t->chassis_type = SMBIOS_ENCLOSURE_DESKTOP;
 	t->bootup_state = SMBIOS_STATE_SAFE;
 	t->power_supply_state = SMBIOS_STATE_SAFE;