[PATCH 1/3] fdt.c: Add non-boottime device tree functions

[Stephen Neuendorffer]

In preparation for providing run-time handling of device trees, factor
out some of the basic functions so that they take an arbitrary blob,
rather than relying on the single boot-time tree.

Signed-off-by: Stephen Neuendorffer <stephen.neuendorffer at xilinx.com>
---
 drivers/of/fdt.c       |  129 ++++++++++++++++++++++++++++++-----------------
 include/linux/of_fdt.h |    9 +++
 2 files changed, 91 insertions(+), 47 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index c1360e0..6ae207a 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -22,6 +22,86 @@
 
 #include <asm/page.h>
 
+char *fdt_get_string(u32 offset,
+			  struct boot_param_header *blob)
+{
+	return ((char *)blob) +
+		be32_to_cpu(blob->off_dt_strings) + offset;
+}
+
+/**
+ * of_get_flat_dt_prop_blob - Given a node in the given flat blob, return
+ * the property ptr
+ *
+ * This function can be used within scan_flattened_dt callback to get
+ * access to properties
+ */
+void *fdt_get_property(unsigned long node, const char *name,
+				 unsigned long *size,
+				 struct boot_param_header *blob)
+{
+	unsigned long p = node;
+
+	do {
+		u32 tag = be32_to_cpup((__be32 *)p);
+		u32 sz, noff;
+		const char *nstr;
+
+		p += 4;
+		if (tag == OF_DT_NOP)
+			continue;
+		if (tag != OF_DT_PROP)
+			return NULL;
+
+		sz = be32_to_cpup((__be32 *)p);
+		noff = be32_to_cpup((__be32 *)(p + 4));
+		p += 8;
+		if (be32_to_cpu(blob->version) < 0x10)
+			p = ALIGN(p, sz >= 8 ? 8 : 4);
+
+		nstr = fdt_get_string(noff, blob);
+		if (nstr == NULL) {
+			pr_warning("Can't find property index name !\n");
+			return NULL;
+		}
+		if (strcmp(name, nstr) == 0) {
+			if (size)
+				*size = sz;
+			return (void *)p;
+		}
+		p += sz;
+		p = ALIGN(p, 4);
+	} while (1);
+}
+
+/**
+ * fdt_is_compatible - Return true if given node from the given blob has
+ * compat in its compatible list
+ * @node: node to test
+ * @compat: compatible string to compare with compatible list.
+ * @blob: A device tree blob
+ */
+int fdt_is_compatible(unsigned long node, const char *compat,
+				 struct boot_param_header *blob)
+{
+	const char *cp;
+	unsigned long cplen, l;
+
+	cp = fdt_get_property(node, "compatible", &cplen, blob);
+	if (cp == NULL)
+		return 0;
+	while (cplen > 0) {
+		if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
+			return 1;
+		l = strlen(cp) + 1;
+		cp += l;
+		cplen -= l;
+	}
+
+	return 0;
+}
+
+/* Everything below here references initial_boot_params directly. */
 int __initdata dt_root_addr_cells;
 int __initdata dt_root_size_cells;
 
@@ -121,38 +201,7 @@ unsigned long __init of_get_flat_dt_root(void)
 void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
 				 unsigned long *size)
 {
-	unsigned long p = node;
-
-	do {
-		u32 tag = be32_to_cpup((__be32 *)p);
-		u32 sz, noff;
-		const char *nstr;
-
-		p += 4;
-		if (tag == OF_DT_NOP)
-			continue;
-		if (tag != OF_DT_PROP)
-			return NULL;
-
-		sz = be32_to_cpup((__be32 *)p);
-		noff = be32_to_cpup((__be32 *)(p + 4));
-		p += 8;
-		if (be32_to_cpu(initial_boot_params->version) < 0x10)
-			p = ALIGN(p, sz >= 8 ? 8 : 4);
-
-		nstr = find_flat_dt_string(noff);
-		if (nstr == NULL) {
-			pr_warning("Can't find property index name !\n");
-			return NULL;
-		}
-		if (strcmp(name, nstr) == 0) {
-			if (size)
-				*size = sz;
-			return (void *)p;
-		}
-		p += sz;
-		p = ALIGN(p, 4);
-	} while (1);
+	return fdt_get_property(node, name, size, initial_boot_params);
 }
 
 /**
@@ -162,21 +211,7 @@ void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
  */
 int __init of_flat_dt_is_compatible(unsigned long node, const char *compat)
 {
-	const char *cp;
-	unsigned long cplen, l;
-
-	cp = of_get_flat_dt_prop(node, "compatible", &cplen);
-	if (cp == NULL)
-		return 0;
-	while (cplen > 0) {
-		if (of_compat_cmp(cp, compat, strlen(compat)) == 0)
-			return 1;
-		l = strlen(cp) + 1;
-		cp += l;
-		cplen -= l;
-	}
-
-	return 0;
+	return fdt_is_compatible(node, compat, initial_boot_params);
 }
 
 static void *__init unflatten_dt_alloc(unsigned long *mem, unsigned long size,
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index 7bbf5b3..864ec47 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -58,6 +58,15 @@ struct boot_param_header {
 };
 
 #if defined(CONFIG_OF_FLATTREE)
+/* For scanning an arbitrary device-tree at any time */
+extern char *fdt_get_string(u32 offset,
+			    struct boot_param_header *blob);
+extern void *fdt_get_property(unsigned long node, const char *name,
+			      unsigned long *size,
+			      struct boot_param_header *blob);
+extern int fdt_is_compatible(unsigned long node, const char *name,
+			     struct boot_param_header *blob);
+
 /* TBD: Temporary export of fdt globals - remove when code fully merged */
 extern int __initdata dt_root_addr_cells;
 extern int __initdata dt_root_size_cells;
-- 
1.5.6.6



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