[POWERPC] Export flat device tree via debugfs for debugging

If DEBUG is turned on in prom.c, export the flat device tree via debugfs.
This has been handy on several occasions.

To look at it:
 # mount -t debugfs none /sys/kernel/debug
 # od -a /sys/kernel/debug/powerpc/flat-device-tree
 and/or
 # dtc -fI dtb /sys/kernel/debug/powerpc/flat-device-tree -O dts

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 483455c5bb02e5ab00ae04ce6a138168e7f8075b..efed4bc2b454573977e53c03d3a91e7e347c1619 100644 (file)
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -30,6 +30,7 @@
 #include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/kexec.h>
+#include <linux/debugfs.h>
 
 #include <asm/prom.h>
 #include <asm/rtas.h>
@@ -2148,3 +2149,27 @@ struct device_node *of_get_cpu_node(int cpu, unsigned int *thread)
        }
        return NULL;
 }
+
+#ifdef DEBUG
+static struct debugfs_blob_wrapper flat_dt_blob;
+
+static int __init export_flat_device_tree(void)
+{
+       struct dentry *d;
+
+       d = debugfs_create_dir("powerpc", NULL);
+       if (!d)
+               return 1;
+
+       flat_dt_blob.data = initial_boot_params;
+       flat_dt_blob.size = initial_boot_params->totalsize;
+
+       d = debugfs_create_blob("flat-device-tree", S_IFREG | S_IRUSR,
+                               d, &flat_dt_blob);
+       if (!d)
+               return 1;
+
+       return 0;
+}
+__initcall(export_flat_device_tree);
+#endif