[PATCH 3.14 29/73] of/base: Fix PowerPC address parsing hack

Greg Kroah-Hartman
2014-12-05T23:25:52Z

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/of/address.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -401,6 +401,21 @@ static struct of_bus *of_match_bus(struc
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)
@@ -426,12 +441,10 @@ static int of_translate_one(struct devic
* 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);