dtc: Enable and fix -Wcast-qual warnings

Enabling -Wcast-qual warnings in dtc shows up a number of places where
we are incorrectly discarding a const qualification.  There are also
some places where we are intentionally discarding the 'const', and we
need an ugly cast through uintptr_t to suppress the warning.  However,
most of these are pretty well isolated with the *_w() functions.  So
in the interests of maximum safety with const qualifications, this
patch enables the warnings and fixes the existing complaints.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Gerald Van Baren <vanbaren@cideas.com>

include/libfdt.h

@@ -125,7 +125,7 @@
 const void *fdt_offset_ptr(const void *fdt, int offset, int checklen);
 static inline void *fdt_offset_ptr_w(void *fdt, int offset, int checklen)
 {
-	return (void *)fdt_offset_ptr(fdt, offset, checklen);
+	return (void *)(uintptr_t)fdt_offset_ptr(fdt, offset, checklen);
 }
 
 uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);
@@ -375,8 +375,8 @@ static inline struct fdt_property *fdt_get_property_w(void *fdt, int nodeoffset,
 						      const char *name,
 						      int *lenp)
 {
-	return (struct fdt_property *)fdt_get_property(fdt, nodeoffset,
-						       name, lenp);
+	return (struct fdt_property *)(uintptr_t)
+		fdt_get_property(fdt, nodeoffset, name, lenp);
 }
 
 /**
@@ -411,7 +411,7 @@ const void *fdt_getprop(const void *fdt, int nodeoffset,
 static inline void *fdt_getprop_w(void *fdt, int nodeoffset,
 				  const char *name, int *lenp)
 {
-	return (void *)fdt_getprop(fdt, nodeoffset, name, lenp);
+	return (void *)(uintptr_t)fdt_getprop(fdt, nodeoffset, name, lenp);
 }
 
 /**

libfdt/fdt_ro.c

@@ -81,7 +81,7 @@ static int nodename_eq(const void *fdt, int offset,
 
 const char *fdt_string(const void *fdt, int stroffset)
 {
-	return (char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
+	return (const char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
 }
 
 int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)

libfdt/fdt_rw.c

@@ -261,7 +261,7 @@ int fdt_set_name(void *fdt, int nodeoffset, const char *name)
 
 	RW_CHECK_HEADER(fdt);
 
-	namep = (char *)fdt_get_name(fdt, nodeoffset, &oldlen);
+	namep = (char *)(uintptr_t)fdt_get_name(fdt, nodeoffset, &oldlen);
 	if (!namep)
 		return oldlen;
 
@@ -436,7 +436,7 @@ int fdt_open_into(const void *fdt, void *buf, int bufsize)
 	/* But if that overlaps with the old tree... */
 	if (((tmp + newsize) > fdtstart) && (tmp < fdtend)) {
 		/* Try right after the old tree instead */
-		tmp = (char *)fdtend;
+		tmp = (char *)(uintptr_t)fdtend;
 		if ((tmp + newsize) > ((char *)buf + bufsize))
 			return -FDT_ERR_NOSPACE;
 	}

libfdt/libfdt_internal.h

@@ -77,19 +77,20 @@ static inline const void *_fdt_offset_ptr(const void *fdt, int offset)
 
 static inline void *_fdt_offset_ptr_w(void *fdt, int offset)
 {
-	return (void *)_fdt_offset_ptr(fdt, offset);
+	return (void *)(uintptr_t)_fdt_offset_ptr(fdt, offset);
 }
 
 static inline const struct fdt_reserve_entry *_fdt_mem_rsv(const void *fdt, int n)
 {
-	const struct fdt_reserve_entry *rsv_table = (struct fdt_reserve_entry *)
+	const struct fdt_reserve_entry *rsv_table =
+		(const struct fdt_reserve_entry *)
 		((const char *)fdt + fdt_off_mem_rsvmap(fdt));
 
 	return rsv_table + n;
 }
 static inline struct fdt_reserve_entry *_fdt_mem_rsv_w(void *fdt, int n)
 {
-	return (void *)_fdt_mem_rsv(fdt, n);
+	return (void *)(uintptr_t)_fdt_mem_rsv(fdt, n);
 }
 
 #define SW_MAGIC		(~FDT_MAGIC)