David Gibson wrote:
> Deleting the irrelevant parts or picking a device tree to pass to
> fdt_init() are both reasonable solutions. libfdt which is included in
> the bootwrapper has functions for removing unwanted nodes: either
> fdt_nop_node() or fdt_del_node() will suffice. There isn't currently
> a dt_ops hook to call though to those functions though. You could
> either add one, or (knowing that your platform always has a flat dt)
> bypass the dt_ops hooks and call libfdt directly.
Thanks. The fdt_del_node approach works pretty nicely. I added a
dt_ops hook since fdt is static in libfdt-wrapper.c.
At first I tried fdt_nop_node, fearing that find_node_by_prop_value()
and fdt_del_node() would interact badly when deleting in mid-traversal,
but it turns out that fdt_nop_node() upsets find_node_by_prop_value()
anyway. Plus, the kernel prints harmless but strange messages when
there are NOPs in the tree. So I use fdt_del_node() and rescan from
the top each time I delete a node and it works fine.
/* Find all product-dependent nodes and delete inapplicable ones. */
dev = NULL;
while ((dev = find_node_by_prop_value(dev,
"product-dependent",
"", 0)) != NULL) {
u32 mask;
int len;
len = getprop(dev, "productmask", &mask, sizeof mask);
if (len == sizeof mask) {
if ((mask & (1 << product_id)) == 0) {
del_node(dev);
/* Have to restart from the beginning. */
dev = NULL;
}
}
}
I had to fix the memcmp bug I mentioned in an earlier posting to allow
searching for a boolean (empty) property.
If anyone cares, below is a trivial patch to expose the del_node()
operation via dt_ops.
Thanks again,
-=] Mike [=-
Index: arch/powerpc/boot/ops.h
===================================================================
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 ops.h
--- arch/powerpc/boot/ops.h 11 Oct 2008 02:51:35 -0000 1.1.1.1
+++ arch/powerpc/boot/ops.h 18 Oct 2008 02:06:45 -0000
@@ -40,6 +40,7 @@
const int buflen);
int (*setprop)(const void *phandle, const char *name,
const void *buf, const int buflen);
+ int (*del_node)(const void *phandle);
void *(*get_parent)(const void *phandle);
/* The node must not already exist. */
void *(*create_node)(const void *parent, const char *name);
@@ -124,6 +125,11 @@
return dt_ops.setprop(devp, name, buf, strlen(buf) + 1);
return -1;
+}
+
+static inline int del_node(const void *devp)
+{
+ return dt_ops.del_node ? dt_ops.del_node(devp) : -1;
}
static inline void *get_parent(const char *devp)
Index: arch/powerpc/boot/libfdt-wrapper.c
===================================================================
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 libfdt-wrapper.c
--- arch/powerpc/boot/libfdt-wrapper.c 11 Oct 2008 02:51:35 -0000 1.1.1.1
+++ arch/powerpc/boot/libfdt-wrapper.c 17 Oct 2008 22:08:44 -0000
@@ -105,6 +105,11 @@
return check_err(rc);
}
+static int fdt_wrapper_del_node(const void *devp)
+{
+ return fdt_del_node(fdt, devp_offset(devp));
+}
+
static void *fdt_wrapper_get_parent(const void *devp)
{
return offset_devp(fdt_parent_offset(fdt, devp_offset(devp)));
@@ -173,6 +178,7 @@
dt_ops.create_node = fdt_wrapper_create_node;
dt_ops.find_node_by_prop_value = fdt_wrapper_find_node_by_prop_value;
dt_ops.find_node_by_compatible = fdt_wrapper_find_node_by_compatible;
+ dt_ops.del_node = fdt_wrapper_del_node;
dt_ops.get_path = fdt_wrapper_get_path;
dt_ops.finalize = fdt_wrapper_finalize;
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