misc: Add gdsys_soc driver

This patch adds a driver for the bus associated with a IHS FPGA.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/drivers/misc/gdsys_soc.h b/drivers/misc/gdsys_soc.h
new file mode 100644
index 0000000..088d3b6
--- /dev/null
+++ b/drivers/misc/gdsys_soc.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2017
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#ifndef _GDSYS_SOC_H_
+#define _GDSYS_SOC_H_
+
+/**
+ * gdsys_soc_get_fpga() - Retrieve pointer to parent bus' FPGA device
+ * @child:	The child device on the FPGA bus needing access to the FPGA.
+ * @fpga:	Pointer to the retrieved FPGA device.
+ *
+ * To access their register maps, devices on gdsys soc buses usually have
+ * facilitate the accessor function of the IHS FPGA their parent bus is
+ * attached to. To access the FPGA device from within the bus' children, this
+ * function returns a pointer to it.
+ *
+ * Return: 0 on success, -ve on failure
+ */
+int gdsys_soc_get_fpga(struct udevice *child, struct udevice **fpga);
+#endif /* _GDSYS_SOC_H_ */