SMBIOS/SCONFIG: Allow devtree-defined Type 41 entries

Introduce the `smbios_dev_info` devicetree keyword to specify the
instance ID and RefDes (Reference Designation) of onboard devices.

Example syntax:

 device pci 1c.0 on	# PCIe Port #1
 	device pci 00.0 on
 		smbios_dev_info 6
 	end
 end
 device pci 1c.1 on	# PCIe Port #2
 	device pci 00.0 on
 		smbios_dev_info 42 "PCIe-PCI Time Machine"
 	end
 end

The `SMBIOS_TYPE41_PROVIDED_BY_DEVTREE` Kconfig option enables using
this syntax to control the generated Type 41 entries. When this option
is enabled, Type 41 entries are only autogenerated for devices with a
defined instance ID. This avoids having to keep track of which instance
IDs have been used for every device class.

Using `smbios_dev_info` when `SMBIOS_TYPE41_PROVIDED_BY_DEVTREE` is not
enabled will result in a build-time error, as the syntax is meaningless
in this case. This is done with preprocessor guards around the Type 41
members in `struct device` and the code which uses the guarded members.
Although the preprocessor usage isn't particularly elegant, adjusting
the devicetree syntax and/or grammar depending on a Kconfig option is
probably even worse.

Change-Id: Iecca9ada6ee1000674cb5dd7afd5c309d8e1a64b
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57370
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/Kconfig b/src/Kconfig
index be269b619536..e4ddf0cc70c2 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -785,6 +785,21 @@ config GENERATE_SMBIOS_TABLES
 
 	  If unsure, say Y.
 
+config SMBIOS_TYPE41_PROVIDED_BY_DEVTREE
+	bool
+	depends on ARCH_X86
+	help
+	  If enabled, only generate SMBIOS Type 41 entries for PCI devices in
+	  the devicetree for which Type 41 information is provided, e.g. with
+	  the `smbios_dev_info` devicetree syntax. This is useful to manually
+	  assign specific instance IDs to onboard devices irrespective of the
+	  device traversal order. It is assumed that instance IDs for devices
+	  of the same class are unique.
+	  When disabled, coreboot autogenerates SMBIOS Type 41 entries for all
+	  appropriate PCI devices in the devicetree. Instance IDs are assigned
+	  successive numbers from a monotonically increasing counter, with one
+	  counter for each device class.
+
 config SMBIOS_PROVIDED_BY_MOBO
 	bool
 	default n