Add a bootwrapper platform (cuboot) that takes a bd_t from a legacy
U-Boot, and inserts data from it into a device tree which has been
compiled into the kernel.  This should help ease the transition to
arch/powerpc in cases where U-Boot has not yet been updated to pass a
device tree, or where upgrading firmware isn't practical.

The device trees currently in the kernel tree must have
/chosen/linux,stdout-path added to work with cuboot.

The kernel command line, mac addresses, and various clocks will be  
filled
in based on the bd_t.

Signed-off-by: Scott Wood <redacted>
---
 arch/powerpc/Kconfig                      |   16 ++++
 arch/powerpc/Makefile                     |    2 +-
 arch/powerpc/boot/.gitignore              |    3 +
 arch/powerpc/boot/Makefile                |   20 ++++-
 arch/powerpc/boot/cuboot-83xx.c           |    4 +
 arch/powerpc/boot/cuboot-85xx.c           |    4 +
 arch/powerpc/boot/cuboot-86xx.c           |    4 +
 arch/powerpc/boot/cuboot.c                |  137 ++++++++++++++++++ 
+++++++++++
 arch/powerpc/boot/ppcboot.h               |  103 ++++++++++++++++++ 
++++
 arch/powerpc/boot/wrapper                 |   46 ++++++++--
 arch/powerpc/platforms/83xx/mpc834x_mds.c |    5 +-
 11 files changed, 329 insertions(+), 15 deletions(-)
 create mode 100644 arch/powerpc/boot/cuboot-83xx.c
 create mode 100644 arch/powerpc/boot/cuboot-85xx.c
 create mode 100644 arch/powerpc/boot/cuboot-86xx.c
 create mode 100644 arch/powerpc/boot/cuboot.c
 create mode 100644 arch/powerpc/boot/ppcboot.h

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6dfbd52..54f7b34 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -967,6 +967,22 @@ config SECCOMP

 	  If unsure, say Y. Only embedded should say N here.

+config CUIMAGE_DTS
+	string "Device tree source file"
+	depends on DEFAULT_UIMAGE
+	help
+	  This specifies the device tree source (.dts) file to be
+	  compiled and included when building the cuImage target.  If a
+	  relative filename is given, then it will be relative to
+	  arch/powerpc/boot/dts.
+
+	  The cuImage target is used for booting on older U-Boot (and
+	  PPCBoot) bootloaders that pass a bd_t instead of a device tree.
+	  Such a kernel will not work with a newer U-Boot that passes the
+	  device tree itself.  If your U-Boot does not mention a device
+	  tree in "help bootm", then use the uImage target instead of
+	  cuImage.
+
 endmenu