Re: svn commit: r271190 - head/sys/dev/ofw

[Nathan Whitehorn]

On 09/06/14 08:34, Ian Lepore wrote:
On Sat, 2014-09-06 at 08:25 -0700, Nathan Whitehorn wrote:
What is this for? The way the specification works here explicitly
requires this fallback.
-Nathan
It's for determining whether there is an entry in the device<->xref
list.  If a node has no xref phandle property there will be no entry for
it in the list and thus no way to record or retrieve a device
association.  I found myself coding the "if it has a phandle, or an
ibm,phandle, or a linux,phandle" incantation, then realized that all
that figuring-out work was done at init time when the xref list is
built, I just needed a way to get the result.

This isn't true. On most but not all real OF systems, which use, or will 
use, the same mechanism, there is no distinction between "regular" and 
"cross-reference" phandles and device tree cross-references still exist 
with no explicit phandle property. So registering a device without a 
phandle property has to to work, and has to fall back to the regular 
phandle 100% of the time.

What may be true is that no single device tree has a mixture of implicit 
and explicit cross-reference handles, so you could set a flag or 
something. But it's probably not worth it. Do you have a concrete 
example where you cared about this?
-Nathan

-- Ian

On 09/06/14 08:11, Ian Lepore wrote:
Author: ian
Date: Sat Sep  6 15:11:35 2014
New Revision: 271190
URL: http://svnweb.freebsd.org/changeset/base/271190

Log:
    Add OF_xref_from_node_strict() which returns -1 if there is no xref handle
    for the node.  The default routine returns the untranslated handle, which
    is sometimes useful, but sometimes you really need to know there's no
    entry in the xref<->node<->device translation table.

Modified:
    head/sys/dev/ofw/openfirm.c
    head/sys/dev/ofw/openfirm.h

Modified: head/sys/dev/ofw/openfirm.c
==============================================================================
--- head/sys/dev/ofw/openfirm.c Sat Sep  6 13:21:07 2014        (r271189)
+++ head/sys/dev/ofw/openfirm.c Sat Sep  6 15:11:35 2014        (r271190)
@@ -554,15 +554,15 @@ OF_node_from_xref(phandle_t xref)
        return (node);
   }
   
-phandle_t
-OF_xref_from_node(phandle_t node)
+static phandle_t
+xref_from_node(phandle_t node, phandle_t notfoundvalue)
   {
        struct xrefinfo *xi;
        phandle_t xref;
   
   	if (xref_init_done) {
                if ((xi = xrefinfo_find(node, FIND_BY_NODE)) == NULL)
-                       return (node);
+                       return (notfoundvalue);
                return (xi->xref);
        }
   
@@ -570,10 +570,24 @@ OF_xref_from_node(phandle_t node)
            -1 && OF_getencprop(node, "ibm,phandle", &xref,
            sizeof(xref)) == -1 && OF_getencprop(node,
            "linux,phandle", &xref, sizeof(xref)) == -1)
-               return (node);
+               return (notfoundvalue);
        return (xref);
   }
   
+phandle_t
+OF_xref_from_node(phandle_t node)
+{
+
+       return (xref_from_node(node, node));
+}
+
+phandle_t
+OF_xref_from_node_strict(phandle_t node)
+{
+
+       return (xref_from_node(node, -1));
+}
+
   device_t
   OF_device_from_xref(phandle_t xref)
   {

Modified: head/sys/dev/ofw/openfirm.h
==============================================================================
--- head/sys/dev/ofw/openfirm.h Sat Sep  6 13:21:07 2014        (r271189)
+++ head/sys/dev/ofw/openfirm.h Sat Sep  6 15:11:35 2014        (r271190)
@@ -128,10 +128,12 @@ ssize_t           OF_package_to_path(phandle_t no
    * Some OF implementations (IBM, FDT) have a concept of effective phandles
    * used for device-tree cross-references. Given one of these, returns the
    * real phandle. If one can't be found (or running on OF implementations
- * without this property), returns its input.
+ * without this property), OF_xref_from_node() returns its input, while the
+ * strict version returns -1.
    */
   phandle_t    OF_node_from_xref(phandle_t xref);
   phandle_t    OF_xref_from_node(phandle_t node);
+phandle_t      OF_xref_from_node_strict(phandle_t node);
   
   /*
    * When properties contain references to other nodes using xref handles it is



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