Subject: + rtc-honor-device-tree-alias-entries-when-assigning-ids.patch added to -mm tree
To: swarren@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 16 Dec 2013 14:48:43 -0800
The patch titled
Subject: rtc: honor device tree /alias entries when assigning IDs
has been added to the -mm tree. Its filename is
rtc-honor-device-tree-alias-entries-when-assigning-ids.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/rtc-honor-device-tree-alias-entries-when-assigning-ids.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/rtc-honor-device-tree-alias-entries-when-assigning-ids.patch
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From: Stephen Warren <swarren@xxxxxxxxxx>
Subject: rtc: honor device tree /alias entries when assigning IDs
Assign RTC device IDs based on device tree /aliases entries if present,
falling back to the existing numbering scheme if there is no /aliases
entry (which includes when the system isn't booted using DT), or there is
a numbering conflict.
This is useful in systems with multiple RTC devices, to ensure that the
best RTC device is selected as /dev/rtc0, which provides the overall
system time.
For example, Tegra has an on-SoC RTC that is not battery backed, typically
coupled with an off-SoC RTC that is battery backed. Only the latter is
useful for populating the system time, yet the former is useful e.g. for
wakeup timing, since the time is not lost when the system is sleeps.
Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/class.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff -puN drivers/rtc/class.c~rtc-honor-device-tree-alias-entries-when-assigning-ids drivers/rtc/class.c
--- a/drivers/rtc/class.c~rtc-honor-device-tree-alias-entries-when-assigning-ids
+++ a/drivers/rtc/class.c
@@ -14,6 +14,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
+#include <linux/of.h>
#include <linux/rtc.h>
#include <linux/kdev_t.h>
#include <linux/idr.h>
@@ -157,12 +158,25 @@ struct rtc_device *rtc_device_register(c
{
struct rtc_device *rtc;
struct rtc_wkalrm alrm;
- int id, err;
+ int of_id, id = -1, err;
+
+ if (dev->of_node) {
+ of_id = of_alias_get_id(dev->of_node, "rtc");
+ if (of_id >= 0) {
+ id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
+ GFP_KERNEL);
+ if (id < 0)
+ dev_warn(dev, "/aliases ID %d not available\n",
+ of_id);
+ }
+ }
- id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
if (id < 0) {
- err = id;
- goto exit;
+ id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
+ if (id < 0) {
+ err = id;
+ goto exit;
+ }
}
rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
_
Patches currently in -mm which might be from swarren@xxxxxxxxxx are
rtc-honor-device-tree-alias-entries-when-assigning-ids.patch
linux-next.patch
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