env: add register_persistent_environment

- heavily copied from register_persistant_environment which was
Signed-off-by: Juergen Beisert <jbe@pengutronix.de>

Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

common/environment.c

@@ -363,3 +363,43 @@ out:
 		free(buf_free);
 	return ret;
 }
+
+#ifdef __BAREBOX__
+/**
+ * Try to register an environment storage on a device's partition
+ * @return 0 on success
+ *
+ * We rely on the existence of a usable storage device, already attached to
+ * our system, to get something like a persistent memory for our environment.
+ * We need to specify the partition number to use on this device.
+ * @param[in] devname Name of the device
+ * @param[in] partnr Partition number
+ * @return 0 on success, anything else in case of failure
+ */
+
+int envfs_register_partition(const char *devname, unsigned int partnr)
+{
+	struct cdev *cdev;
+	char *partname;
+
+	if (!devname)
+		return -EINVAL;
+
+	cdev = cdev_by_name(devname);
+	if (cdev == NULL) {
+		pr_err("No %s present\n", devname);
+		return -ENODEV;
+	}
+	partname = asprintf("%s.%d", devname, partnr);
+	cdev = cdev_by_name(partname);
+	if (cdev == NULL) {
+		pr_err("No %s partition available\n", partname);
+		pr_info("Please create the partition %s to store the env\n", partname);
+		return -ENODEV;
+	}
+
+	return devfs_add_partition(partname, 0, cdev->size,
+						DEVFS_PARTITION_FIXED, "env0");
+}
+EXPORT_SYMBOL(envfs_register_partition);
+#endif

include/envfs.h

@@ -96,4 +96,6 @@ int envfs_save(char *filename, char *dirname);
 /* defaults to /dev/env0 */
 extern char *default_environment_path;
 
+int envfs_register_partition(const char *devname, unsigned int partnr);
+
 #endif /* _ENVFS_H */