[POWERPC] Cleanup zImage handling of kernel entry with flat device tree

This makes 2 changes to clean up the flat device tree handling
logic in the zImage wrapper.

First, there were two callbacks from the dt_ops structure used for
producing a final flat tree to pass to the kerne: dt_ops.ft_pack()
which packed the flat tree (possibly a no-op) and dt_ops.ft_addr()
which retreived the address of the final blob.  Since they were only
ever called together, this patch combines the two into a single new
callback, dt_ops.finalize().  This new callback does whatever
platform-dependent things are necessary to produce a final flat device
tree blob, and returns the blob's addres.

Second, the current logic calls the kernel with a flat device tree if
one is build into the zImage wrapper, otherwise it boots the kernel
with a PROM pointer, expecting the kernel to copy the OF device tree
itself.  This approach precludes the possibility of the platform
wrapper code building a flat device tree from whatever
platform-specific information firmware provides.  Thus, this patch
takes the more sensible approach of invoking the kernel with a flat
tree if the dt_ops.finalize callback provides one (by whatever means).

So, the dt_ops.finalize callback can be NULL, or can be a function
which returns NULL.  In either case, the zImage wrapper logic assumes
that this is a platform with OF and invokes the kernel accordingly.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 11 insertions, 4 deletions

diff --git a/arch/powerpc/boot/main.c b/arch/powerpc/boot/main.c
index 630a453e16fa..6f6b50d238b6 100644
--- a/arch/powerpc/boot/main.c
+++ b/arch/powerpc/boot/main.c
@@ -298,6 +298,7 @@ void start(unsigned long a1, unsigned long a2, void *promptr, void *sp)
 {
 	kernel_entry_t kentry;
 	char cmdline[COMMAND_LINE_SIZE];
+	unsigned long ft_addr = 0;
 
 	memset(__bss_start, 0, _end - __bss_start);
 	memset(&platform_ops, 0, sizeof(platform_ops));
@@ -328,14 +329,20 @@ void start(unsigned long a1, unsigned long a2, void *promptr, void *sp)
 		set_cmdline(cmdline);
 	}
 
+	printf("Finalizing device tree...");
+	if (dt_ops.finalize)
+		ft_addr = dt_ops.finalize();
+	if (ft_addr)
+		printf(" flat tree at 0x%lx\n\r", ft_addr);
+	else
+		printf(" using OF tree (promptr=%p)\n\r", promptr);
+
 	if (console_ops.close)
 		console_ops.close();
 
 	kentry = (kernel_entry_t) vmlinux.addr;
-	if (_dtb_end > _dtb_start) {
-		dt_ops.ft_pack();
-		kentry(dt_ops.ft_addr(), 0, NULL);
-	}
+	if (ft_addr)
+		kentry(ft_addr, 0, NULL);
 	else
 		/* XXX initrd addr/size should be passed in properties */
 		kentry(initrd.addr, initrd.size, promptr);