of/base: Fix PowerPC address parsing hack

commit 746c9e9f92dde2789908e51a354ba90a1962a2eb upstream.

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>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
[bwh: Backported to 3.2: use #ifdef because IS_ENABLED() only works for
 config symbols that are defined on the current architecture]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 45c1727..53a613f 100644 (file)
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -333,6 +333,22 @@ static struct of_bus *of_match_bus(struct device_node *np)
        return NULL;
 }
 
+static int of_empty_ranges_quirk(void)
+{
+#ifdef 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;
+#else
+       return false;
+#endif
+}
+
 static int of_translate_one(struct device_node *parent, struct of_bus *bus,
                            struct of_bus *pbus, u32 *addr,
                            int na, int ns, int pna, const char *rprop)
@@ -358,12 +374,10 @@ 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);