[PATCH] mtd: mtdconcat: map through panic write handler

[Matt Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx>]

Allows a mtdconcat's subdevice->_panic_write to be used for
capturing a mtdoops dump.

Note: The ->_panic_write is mapped through from the first chip
      that is part of the concat virtual device.

Signed-off-by: Matthew Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx>
---
 drivers/mtd/mtdconcat.c | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index cbc5925e6440..af99a5af601e 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -116,6 +116,48 @@ concat_read(struct mtd_info *mtd, loff_t from, size_t len,
 	return -EINVAL;
 }
 
+static int
+concat_panic_write(struct mtd_info *mtd, loff_t to, size_t len,
+	     size_t * retlen, const u_char * buf)
+{
+	struct mtd_concat *concat = CONCAT(mtd);
+	int err = -EINVAL;
+	int i;
+	for (i = 0; i < concat->num_subdev; i++) {
+		struct mtd_info *subdev = concat->subdev[i];
+		size_t size, retsize;
+
+		if (to >= subdev->size) {
+			size = 0;
+			to -= subdev->size;
+			continue;
+		}
+		if (to + len > subdev->size)
+			size = subdev->size - to;
+		else
+			size = len;
+
+		err = mtd_panic_write(subdev, to, size, &retsize, buf);
+		if (err == -EOPNOTSUPP) {
+			printk(KERN_ERR "mtdconcat: Cannot write from panic without panic_write\n");
+			return;
+		}
+		if (err)
+			break;
+
+		*retlen += retsize;
+		len -= size;
+		if (len == 0)
+			break;
+
+		err = -EINVAL;
+		buf += size;
+		to = 0;
+	}
+	return err;
+}
+
+
 static int
 concat_write(struct mtd_info *mtd, loff_t to, size_t len,
 	     size_t * retlen, const u_char * buf)
@@ -660,6 +702,8 @@ struct mtd_info *mtd_concat_create(struct mtd_info *subdev[],	/* subdevices to c
 		concat->mtd._block_isbad = concat_block_isbad;
 	if (subdev[0]->_block_markbad)
 		concat->mtd._block_markbad = concat_block_markbad;
+	if (subdev[0]->_panic_write)
+		concat->mtd._panic_write = concat_panic_write;
 
 	concat->mtd.ecc_stats.badblocks = subdev[0]->ecc_stats.badblocks;
 
-- 
2.17.1


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