mtd: nand: add 'oob_required' argument to NAND {read,write}_page interfaces

New NAND controllers can perform read/write via HW engines which don't expose
OOB data in their DMA mode. To reflect this, we should rework the nand_chip /
nand_ecc_ctrl interfaces that assume that drivers will always read/write OOB
data in the nand_chip.oob_poi buffer. A better interface includes a boolean
argument that explicitly tells the callee when OOB data is requested by the
calling layer (for reading/writing to/from nand_chip.oob_poi).

This patch adds the 'oob_required' parameter to each relevant {read,write}_page
interface; all 'oob_required' parameters are left unused for now. The next
patch will set the parameter properly in the nand_base.c callers, and follow-up
patches will make use of 'oob_required' in some of the callee functions.

Note that currently, there is no harm in ignoring the 'oob_required' parameter
and *always* utilizing nand_chip.oob_poi, but there can be
performance/complexity/design benefits from avoiding filling oob_poi in the
common case. I will try to implement this for some drivers which can be ported
easily.

Note: I couldn't compile-test all of these easily, as some had ARCH
dependencies.

[dwmw2: Merge later 1/0 vs. true/false cleanup]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Acked-by: Jiandong Zheng <jdzheng@broadcom.com>
Acked-by: Mike Dunn <mikedunn@newsguy.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/mtd/nand/bcm_umi_bch.c b/drivers/mtd/nand/bcm_umi_bch.c
index f8472b49567a..5914bb32e001 100644
--- a/drivers/mtd/nand/bcm_umi_bch.c
+++ b/drivers/mtd/nand/bcm_umi_bch.c
@@ -22,9 +22,9 @@
 
 /* ---- Private Function Prototypes -------------------------------------- */
 static int bcm_umi_bch_read_page_hwecc(struct mtd_info *mtd,
-	struct nand_chip *chip, uint8_t *buf, int page);
+	struct nand_chip *chip, uint8_t *buf, int oob_required, int page);
 static void bcm_umi_bch_write_page_hwecc(struct mtd_info *mtd,
-	struct nand_chip *chip, const uint8_t *buf);
+	struct nand_chip *chip, const uint8_t *buf, int oob_required);
 
 /* ---- Private Variables ------------------------------------------------ */
 
@@ -103,11 +103,12 @@ static struct nand_ecclayout nand_hw_eccoob_4096 = {
 *  @mtd:	mtd info structure
 *  @chip:	nand chip info structure
 *  @buf:	buffer to store read data
+*  @oob_required:	caller expects OOB data read to chip->oob_poi
 *
 ***************************************************************************/
 static int bcm_umi_bch_read_page_hwecc(struct mtd_info *mtd,
 				       struct nand_chip *chip, uint8_t * buf,
-						 int page)
+				       int oob_required, int page)
 {
 	int sectorIdx = 0;
 	int eccsize = chip->ecc.size;
@@ -190,10 +191,11 @@ static int bcm_umi_bch_read_page_hwecc(struct mtd_info *mtd,
 *  @mtd:	mtd info structure
 *  @chip:	nand chip info structure
 *  @buf:	data buffer
+*  @oob_required:	must write chip->oob_poi to OOB
 *
 ***************************************************************************/
 static void bcm_umi_bch_write_page_hwecc(struct mtd_info *mtd,
-	struct nand_chip *chip, const uint8_t *buf)
+	struct nand_chip *chip, const uint8_t *buf, int oob_required)
 {
 	int sectorIdx = 0;
 	int eccsize = chip->ecc.size;