linux-kernel - [PATCH] watchdog_dev: Use device tree alias for naming watchdogs

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Date:	Wed, 2 Sep 2015 11:00:17 -0700
From:	Justin Chen <justinpopo6@...il.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<wim@...ana.be>, <linux-watchdog@...r.kernel.org>,
	<linux@...ck-us.net>, <bcm-kernel-feedback-list@...adcom.com>,
	Justin Chen <justinpopo6@...il.com>
Subject: [PATCH] watchdog_dev: Use device tree alias for naming watchdogs

Currently there is no way to easily differentiate multiple
watchdog devices. The watchdogs are named by the order they
are probed.
1st probed watchdog: /dev/watchdog0
2nd probed watchdog: /dev/watchdog1
...

This change uses the alias of the watchdog device node for
the name of the watchdog.
aliases {
    watchdog0 = "/...../...."
    watchdog3 = "/..../....."
    watchdog2 = "/..../....."
    ...
}

This will translate to...
/dev/watchdog0
/dev/watchdog3
/dev/watchdog2

v2
Assign alias number to id in watchdog_core instead of watchdog_dev.
If failed to get id, fallback to original ida_simple_get call.

Signed-off-by: Justin Chen <justinpopo6@...il.com>
---
 drivers/watchdog/watchdog_core.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 1a80594..873f139 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -139,7 +139,7 @@ EXPORT_SYMBOL_GPL(watchdog_init_timeout);
 
 static int __watchdog_register_device(struct watchdog_device *wdd)
 {
-	int ret, id, devno;
+	int ret, id = -1, devno;
 
 	if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
 		return -EINVAL;
@@ -157,7 +157,18 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 	 */
 
 	mutex_init(&wdd->lock);
-	id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
+
+	/* Use alias for watchdog id if possible */
+	if (wdd->parent) {
+		ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
+		if (ret >= 0)
+			id = ida_simple_get(&watchdog_ida, ret,
+					    ret + 1, GFP_KERNEL);
+	}
+
+	if (id < 0)
+		id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
+
 	if (id < 0)
 		return id;
 	wdd->id = id;
-- 
2.1.0

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