watchdog: pretimeout: add pretimeout_available_governors attribute

The change adds an option to a user with CONFIG_WATCHDOG_SYSFS and
CONFIG_WATCHDOG_PRETIMEOUT_GOV enabled to get information about all
registered watchdog pretimeout governors by reading watchdog device
attribute named "pretimeout_available_governors".

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c
index c9e4a03..9db07bf 100644
--- a/drivers/watchdog/watchdog_pretimeout.c
+++ b/drivers/watchdog/watchdog_pretimeout.c
@@ -52,6 +52,21 @@
 	return NULL;
 }
 
+int watchdog_pretimeout_available_governors_get(char *buf)
+{
+	struct governor_priv *priv;
+	int count = 0;
+
+	mutex_lock(&governor_lock);
+
+	list_for_each_entry(priv, &governor_list, entry)
+		count += sprintf(buf + count, "%s\n", priv->gov->name);
+
+	mutex_unlock(&governor_lock);
+
+	return count;
+}
+
 int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf)
 {
 	int count = 0;