[U-Boot] [PATCH] fdt: Fix fdtdec_get_addr_size() for 64-bit

[Stephen Warren]

From: Thierry Reding <treding at nvidia.com>

Signed-off-by: Thierry Reding <treding at nvidia.com>
Signed-off-by: Tom Warren <twarren at nvidia.com>
Signed-off-by: Stephen Warren <swarren at nvidia.com>
---
Simon,

When Thierry first posted this patch, you responded:

> > +       parent = fdt_parent_offset(blob, node);
>
> This function is very slow as it must scan the whole tree. Can we
> instead pass in the parent node?

I don't think that's possible in general. This function is called from
fdtdec_get_addr(), and it's easy to find call sites of that function that
don't have the parent node available. IIRC, the first couple of example I
found scan the DT for a node with a certain compatible value, or look up
nodes via aliases, rather than being called while parsing the DT in a
top-down tree-like fashion, where the parent node is easily available. I
didn't do an exhaustive search after I found a few problematic cases.

> Also, how about (in addition) a
> version of this function that works for devices? Like:
>
> device_get_addr_size(struct udevice *dev, ...)
>
> so that it can handle this for you.

That sounds like a separate patch?

Equally, I see that struct udevice contains an of_offset field, but no
parent_of_offset or similar. There is a struct udevice *parent though;
is the struct udevice hierarchy guaranteed to 100% match the DT
hierarchy? I know this isn't necessarily guaranteed in Linux's device
model for example.

As such, this patch seems OK to me as-is.
---
 lib/fdtdec.c | 56 ++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 20 deletions(-)

diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 9c6b3619da24..56e72eafaade 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -88,29 +88,45 @@ const char *fdtdec_get_compatible(enum fdt_compat_id id)
 fdt_addr_t fdtdec_get_addr_size(const void *blob, int node,
 		const char *prop_name, fdt_size_t *sizep)
 {
-	const fdt_addr_t *cell;
-	int len;
+	const fdt32_t *ptr, *end;
+	int parent, na, ns, len;
+	fdt_addr_t addr;
 
 	debug("%s: %s: ", __func__, prop_name);
-	cell = fdt_getprop(blob, node, prop_name, &len);
-	if (cell && ((!sizep && len == sizeof(fdt_addr_t)) ||
-		     len == sizeof(fdt_addr_t) * 2)) {
-		fdt_addr_t addr = fdt_addr_to_cpu(*cell);
-		if (sizep) {
-			const fdt_size_t *size;
-
-			size = (fdt_size_t *)((char *)cell +
-					sizeof(fdt_addr_t));
-			*sizep = fdt_size_to_cpu(*size);
-			debug("addr=%08lx, size=%llx\n",
-			      (ulong)addr, (u64)*sizep);
-		} else {
-			debug("%08lx\n", (ulong)addr);
-		}
-		return addr;
+
+	parent = fdt_parent_offset(blob, node);
+	if (parent < 0) {
+		debug("(no parent found)\n");
+		return FDT_ADDR_T_NONE;
 	}
-	debug("(not found)\n");
-	return FDT_ADDR_T_NONE;
+
+	na = fdt_address_cells(blob, parent);
+	ns = fdt_size_cells(blob, parent);
+
+	ptr = fdt_getprop(blob, node, prop_name, &len);
+	if (!ptr) {
+		debug("(not found)\n");
+		return FDT_ADDR_T_NONE;
+	}
+
+	end = ptr + len / sizeof(*ptr);
+
+	if (ptr + na + ns > end) {
+		debug("(not enough data: expected %d bytes, got %d bytes)\n",
+		      (na + ns) * 4, len);
+		return FDT_ADDR_T_NONE;
+	}
+
+	addr = fdtdec_get_number(ptr, na);
+
+	if (sizep) {
+		*sizep = fdtdec_get_number(ptr + na, ns);
+		debug("addr=%pa, size=%pa\n", &addr, sizep);
+	} else {
+		debug("%pa\n", &addr);
+	}
+
+	return addr;
 }
 
 fdt_addr_t fdtdec_get_addr(const void *blob, int node,
-- 
1.9.1