common: machine_id: introduce machine id generation

This patch adds functionality to pass device-specific information that
will be hashed to generate a persistent unique machine id. It is then
available as global.machine_id. It can be overwritten with
nv.machine_id if necessary. Passing the machine id to the kernel is
done in a separate patch.

Note: if multiple sources provide hashable device-specific information
(via machine_id_set_hashable()) the information provided by the last call
prior to the late initcall set_machine_id() is used to generate the
machine id from. Thus when updating barebox the machine id might change.

Signed-off-by: Bastian Krause <bst@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/machine_id.h b/include/machine_id.h
new file mode 100644
index 0000000000..31d5e0bb28
--- /dev/null
+++ b/include/machine_id.h
@@ -0,0 +1,16 @@
+#ifndef __MACHINE_ID_H__
+#define __MACHINE_ID_H__
+
+#if IS_ENABLED(CONFIG_MACHINE_ID)
+
+void machine_id_set_hashable(const void *hashable, size_t len);
+
+#else
+
+static inline void machine_id_set_hashable(const void *hashable, size_t len)
+{
+}
+
+#endif /* CONFIG_MACHINE_ID */
+
+#endif  /* __MACHINE_ID_H__ */