[v2,4/7] mtd: mtd_raid: introduce raid single implementation

diff --git a/drivers/mtd/mtd_raid/raid_single.c b/drivers/mtd/mtd_raid/raid_single.c
new file mode 100644
index 0000000..d72df5df
--- /dev/null
+++ b/drivers/mtd/mtd_raid/raid_single.c
@@ -0,0 +1,156 @@ 
+/*
+ * This file is part of MTD RAID.
+ *
+ * Copyright (C) 2015 Dongsheng Yang. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Authors: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
+ */
+
+/*
+ * This file implement single raild level.
+ *
+ * RAID_SINGLE:
+ *
+ * Flash A:
+ * 	------------------------------
+ * 	|  A1   |  A2   | ... |  An  |
+ * 	------------------------------
+ * Flash B:
+ * 	------------------------------
+ * 	|  B1   |  B2   | ... |  Bn  |
+ * 	------------------------------
+ * Flash C:
+ * 	------------------------------
+ * 	|  C1   |  C2   | ... |  Cn  |
+ * 	------------------------------
+ *
+ * RAID_SINGLE:
+ * 	---------------------------------------------------------------------
+ * 	|  A1   |  A2  | ... |  An  |  B1  | ... |  Bn  |  C1  | ... |  Cn  |
+ * 	---------------------------------------------------------------------
+ *
+ * It works similarly with concat.
+ */
+#include <linux/kthread.h>
+#include <linux/slab.h>
+
+#include "mtd_raid.h"
+
+/**
+ *
+ */
+static int raid_single_logical_to_physical(struct mtd_raid *raid, loff_t from, size_t len, int copy_num,
+					   int *devid, loff_t *subdev_off, size_t *size)
+{
+	struct mtd_info *subdev = NULL;
+	int i = 0;
+
+	*subdev_off = from;
+	for (i = 0; i < raid->dev_count; i++) {
+		subdev = raid->devs[i].mtd;
+		if (from >= subdev->size) {
+			from -= subdev->size;
+			*subdev_off = 0;
+			*size = 0;
+			continue;
+		}
+
+		*subdev_off = from;
+		if (from + len > subdev->size)
+			*size = subdev->size - *subdev_off;
+		else
+			*size = len;
+
+		*devid = i;
+		break;
+	}
+
+	if (i == raid->dev_count)
+		return -EINVAL;
+
+	return 0;
+}
+
+struct mtd_raid *mtd_raid_single_create(int dev_count, size_t substripe_size)
+{
+	struct mtd_raid_single *raid_single = NULL;
+	struct mtd_raid *raid = NULL;
+
+	raid_single = kzalloc(sizeof(struct mtd_raid_single) + sizeof(struct mtd_raid_dev) * dev_count, GFP_KERNEL);
+	if (!raid_single)
+		goto out;
+
+	raid = &raid_single->raid;
+	raid->raid_level = MTD_RAID_LEVEL_SINGLE;
+	raid->ops = &mtd_raid_single_ops;
+	raid->ncopies = 1;
+	raid->npebs_per_leb = 1;
+
+	return &raid_single->raid;
+out:
+	return NULL;
+}
+
+static int raid_single_init(struct mtd_raid *raid,
+			    int dev_count, size_t substripe_size)
+{
+	int ret = 0;
+	int i = 0;
+	int raid_id = 0;
+	struct mtd_info *mtd = &raid->mtd;
+	struct mtd_info *subdev = raid->devs[0].mtd;
+
+	raid_id = mtd_raid_list_register(MTD_RAID_LEVEL_SINGLE, raid);
+	sprintf(raid->name, "mtdsingle-%d", raid_id);
+	mtd->name = raid->name;
+
+	/*
+	 * Same erasesize with subdevs
+	 **/
+	mtd->erasesize = subdev->erasesize;
+	for (i = 0; i < dev_count; i++) {
+		subdev = raid->devs[i].mtd;
+		if (mtd->erasesize != subdev->erasesize) {
+			pr_err("Incompatible erasesize on \"%s\"",
+			       subdev->name);
+			ret = -EINVAL;
+			goto err;
+		}
+		/*
+		 * mtd->size is the sum of all subdevs
+		 **/
+		mtd->size += subdev->size;
+	}
+	return ret;
+err:
+	mtd_raid_list_unregister(raid);
+	return ret;
+}
+
+
+static void raid_single_destroy(struct mtd_raid *mtd_raid)
+{
+	struct mtd_raid_single *raid_single = MTD_RAID_SINGLE(mtd_raid);
+
+	mtd_raid_list_unregister(&raid_single->raid);
+	kfree(raid_single);
+}
+
+const struct mtd_raid_operations mtd_raid_single_ops = {
+	.init    = raid_single_init,
+	.destroy = raid_single_destroy,
+	.logical_to_physical  = raid_single_logical_to_physical,
+};