of/base: Fix PowerPC address parsing hack

We have a historical hack that treats missing ranges properties as the
equivalent of an empty one. This is needed for ancient PowerMac "bad"
device-trees, and shouldn't be enabled for any other PowerPC platform,
otherwise we get some nasty layout of devices in sysfs or even
duplication when a set of otherwise identically named devices is
created multiple times under a different parent node with no ranges
property.

This fix is needed for the PowerNV i2c busses to be exposed properly
and will fix a number of other embedded cases.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/of/address.c b/drivers/of/address.c
index afdb78299f61..06af494184d6 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -450,6 +450,21 @@ static struct of_bus *of_match_bus(struct device_node *np)
         return NULL;
 }
 
+static int of_empty_ranges_quirk(void)
+{
+        if (IS_ENABLED(CONFIG_PPC)) {
+                /* To save cycles, we cache the result */
+                static int quirk_state = -1;
+
+                if (quirk_state < 0)
+                        quirk_state =
+                                of_machine_is_compatible("Power Macintosh") ||
+                                of_machine_is_compatible("MacRISC");
+                return quirk_state;
+        }
+        return false;
+}
+
 static int of_translate_one(struct device_node *parent, struct of_bus *bus,
                             struct of_bus *pbus, __be32 *addr,
                             int na, int ns, int pna, const char *rprop)
@@ -475,12 +490,10 @@ static int of_translate_one(struct device_node *parent, struct of_bus *bus,
          * This code is only enabled on powerpc. --gcl
          */
         ranges = of_get_property(parent, rprop, &rlen);
-#if !defined(CONFIG_PPC)
-        if (ranges == NULL) {
+        if (ranges == NULL && !of_empty_ranges_quirk()) {
                 pr_err("OF: no ranges; cannot translate\n");
                 return 1;
         }
-#endif /* !defined(CONFIG_PPC) */
         if (ranges == NULL || rlen == 0) {
                 offset = of_read_number(addr, na);
                 memset(addr, 0, pna * 4);