[MTD] Rework the out of band handling completely

Hopefully the last iteration on this!

The handling of out of band data on NAND was accompanied by tons of fruitless
discussions and halfarsed patches to make it work for a particular
problem. Sufficiently annoyed by I all those "I know it better" mails and the
resonable amount of discarded "it solves my problem" patches, I finally decided
to go for the big rework. After removing the _ecc variants of mtd read/write
functions the solution to satisfy the various requirements was to refactor the
read/write _oob functions in mtd.

The major change is that read/write_oob now takes a pointer to an operation
descriptor structure "struct mtd_oob_ops".instead of having a function with at
least seven arguments.

read/write_oob which should probably renamed to a more descriptive name, can do
the following tasks:

- read/write out of band data
- read/write data content and out of band data
- read/write raw data content and out of band data (ecc disabled)

struct mtd_oob_ops has a mode field, which determines the oob handling mode.

Aside of the MTD_OOB_RAW mode, which is intended to be especially for
diagnostic purposes and some internal functions e.g. bad block table creation,
the other two modes are for mtd clients:

MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is
described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's
up to the caller to make sure that the byte positions are not used by the ECC
placement algorithms.

MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in
the out of band area which are described by the oobfree tuples in the ecclayout
data structre which is associated to the devicee.

The decision whether data plus oob or oob only handling is done depends on the
setting of the datbuf member of the data structure. When datbuf == NULL then
the internal read/write_oob functions are selected, otherwise the read/write
data routines are invoked.

Tested on a few platforms with all variants. Please be aware of possible
regressions for your particular device / application scenario

Disclaimer: Any whining will be ignored from those who just contributed "hot
air blurb" and never sat down to tackle the underlying problem of the mess in
the NAND driver grown over time and the big chunk of work to fix up the
existing users. The problem was not the holiness of the existing MTD
interfaces. The problems was the lack of time to go for the big overhaul. It's
easy to add more mess to the existing one, but it takes alot of effort to go
for a real solution.

Improvements and bugfixes are welcome!

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 43 insertions, 10 deletions

diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index a0d3f011c0f2..84ec40d25438 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -671,7 +671,7 @@ out:
 }
 
 /**
- * onenand_read_oob - [MTD Interface] OneNAND read out-of-band
+ * onenand_do_read_oob - [MTD Interface] OneNAND read out-of-band
  * @param mtd		MTD device structure
  * @param from		offset to read from
  * @param len		number of bytes to read
@@ -680,8 +680,8 @@ out:
  *
  * OneNAND read out-of-band data from the spare area
  */
-static int onenand_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
-	size_t *retlen, u_char *buf)
+int onenand_do_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
+			size_t *retlen, u_char *buf)
 {
 	struct onenand_chip *this = mtd->priv;
 	int read = 0, thislen, column;
@@ -744,6 +744,21 @@ out:
 	return ret;
 }
 
+/**
+ * onenand_read_oob - [MTD Interface] NAND write data and/or out-of-band
+ * @mtd:	MTD device structure
+ * @from:	offset to read from
+ * @ops:	oob operation description structure
+ */
+static int onenand_read_oob(struct mtd_info *mtd, loff_t from,
+			    struct mtd_oob_ops *ops)
+{
+	BUG_ON(ops->mode != MTD_OOB_PLACE);
+
+	return onenand_do_read_oob(mtd, from + ops->ooboffs, ops->len,
+				   &ops->retlen, ops->oobbuf);
+}
+
 #ifdef CONFIG_MTD_ONENAND_VERIFY_WRITE
 /**
  * onenand_verify_oob - [GENERIC] verify the oob contents after a write
@@ -894,7 +909,7 @@ out:
 }
 
 /**
- * onenand_write_oob - [MTD Interface] OneNAND write out-of-band
+ * onenand_do_write_oob - [Internal] OneNAND write out-of-band
  * @param mtd		MTD device structure
  * @param to		offset to write to
  * @param len		number of bytes to write
@@ -903,8 +918,8 @@ out:
  *
  * OneNAND write out-of-band
  */
-static int onenand_write_oob(struct mtd_info *mtd, loff_t to, size_t len,
-	size_t *retlen, const u_char *buf)
+static int onenand_do_write_oob(struct mtd_info *mtd, loff_t to, size_t len,
+				size_t *retlen, const u_char *buf)
 {
 	struct onenand_chip *this = mtd->priv;
 	int column, ret = 0;
@@ -973,6 +988,21 @@ out:
 }
 
 /**
+ * onenand_write_oob - [MTD Interface] NAND write data and/or out-of-band
+ * @mtd:	MTD device structure
+ * @from:	offset to read from
+ * @ops:	oob operation description structure
+ */
+static int onenand_write_oob(struct mtd_info *mtd, loff_t to,
+			     struct mtd_oob_ops *ops)
+{
+	BUG_ON(ops->mode != MTD_OOB_PLACE);
+
+	return onenand_do_write_oob(mtd, to + ops->ooboffs, ops->len,
+				    &ops->retlen, ops->oobbuf);
+}
+
+/**
  * onenand_block_checkbad - [GENERIC] Check if a block is marked bad
  * @param mtd		MTD device structure
  * @param ofs		offset from device start
@@ -1138,7 +1168,7 @@ static int onenand_default_block_markbad(struct mtd_info *mtd, loff_t ofs)
 
         /* We write two bytes, so we dont have to mess with 16 bit access */
         ofs += mtd->oobsize + (bbm->badblockpos & ~0x01);
-        return mtd->write_oob(mtd, ofs , 2, &retlen, buf);
+        return onenand_do_write_oob(mtd, ofs , 2, &retlen, buf);
 }
 
 /**
@@ -1328,7 +1358,7 @@ static int do_otp_lock(struct mtd_info *mtd, loff_t from, size_t len,
 	this->command(mtd, ONENAND_CMD_OTP_ACCESS, 0, 0);
 	this->wait(mtd, FL_OTPING);
 
-	ret = mtd->write_oob(mtd, from, len, retlen, buf);
+	ret = onenand_do_write_oob(mtd, from, len, retlen, buf);
 
 	/* Exit OTP access mode */
 	this->command(mtd, ONENAND_CMD_RESET, 0, 0);
diff --git a/drivers/mtd/onenand/onenand_bbt.c b/drivers/mtd/onenand/onenand_bbt.c
index aafd7c2f7802..1b00dac3d7d6 100644
--- a/drivers/mtd/onenand/onenand_bbt.c
+++ b/drivers/mtd/onenand/onenand_bbt.c
@@ -17,6 +17,9 @@
 #include <linux/mtd/onenand.h>
 #include <linux/mtd/compatmac.h>
 
+extern int onenand_do_read_oob(struct mtd_info *mtd, loff_t from, size_t len,
+			       size_t *retlen, u_char *buf);
+
 /**
  * check_short_pattern - [GENERIC] check if a pattern is in the buffer
  * @param buf		the buffer to search
@@ -87,8 +90,8 @@ static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr
 
 			/* No need to read pages fully,
 			 * just read required OOB bytes */
-			ret = mtd->read_oob(mtd, from + j * mtd->writesize + bd->offs,
-						readlen, &retlen, &buf[0]);
+			ret = onenand_do_read_oob(mtd, from + j * mtd->writesize + bd->offs,
+						  readlen, &retlen, &buf[0]);
 
 			if (ret)
 				return ret;