dm: Don't allow U_BOOT_DEVICE() when of-platdata is used

With of-platdata, the devicetree is supposed to specify all the devices
in the system. So far this hasn't really mattered since of-platdata still
works correctly.

However, new of-platdata features rely on numbering the devices in a
particular order so that they can be referenced by a single integer. It is
tricky to implement this efficiently when other devices are present in the
build.

To address this, disable use of U_BOOT_DEVICE() when of-platdata is
enabled. This seems acceptable as it is not supposed to be used at all,
except in SPL/TPL, where of-platdata is the recommended approach.

This breaks one non-compliant boards at present: mx6cuboxi

Signed-off-by: Simon Glass <sjg@chromium.org>
(disable CONFIG_IMX_THERMAL for mx6cuboxi to avoid a build error)

include/dm/platdata.h

@@ -55,9 +55,17 @@ struct driver_rt {
  * NOTE: Avoid using these except in extreme circumstances, where device tree
  * is not feasible (e.g. serial driver in SPL where <8KB of SRAM is
  * available). U-Boot's driver model uses device tree for configuration.
+ *
+ * When of-platdata is in use, U_BOOT_DEVICE() cannot be used outside of the
+ * dt-platdata.c file created by dtoc
  */
+#if CONFIG_IS_ENABLED(OF_PLATDATA) && !defined(DT_PLATDATA_C)
+#define U_BOOT_DEVICE(__name)	_Static_assert(false, \
+	"Cannot use U_BOOT_DEVICE with of-platdata. Please use devicetree instead")
+#else
 #define U_BOOT_DEVICE(__name)						\
 	ll_entry_declare(struct driver_info, __name, driver_info)
+#endif
 
 /* Declare a list of devices. The argument is a driver_info[] array */
 #define U_BOOT_DEVICES(__name)						\

tools/dtoc/dtb_platdata.py

@@ -673,6 +673,9 @@ class DtbPlatdata(object):
         information.
         """
         self.out_header()
+        self.out('/* Allow use of U_BOOT_DEVICE() in this file */\n')
+        self.out('#define DT_PLATDATA_C\n')
+        self.out('\n')
         self.out('#include <common.h>\n')
         self.out('#include <dm.h>\n')
         self.out('#include <dt-structs.h>\n')

tools/dtoc/test_dtoc.py

@@ -44,6 +44,9 @@ C_HEADER = '''/*
  * This file was generated by dtoc from a .dtb (device tree binary) file.
  */
 
+/* Allow use of U_BOOT_DEVICE() in this file */
+#define DT_PLATDATA_C
+
 #include <common.h>
 #include <dm.h>
 #include <dt-structs.h>