[PATCH 1/3] mtd: rawnand: Add a helper to check if a CHANGE_READ_COLUMN is possible

[Miquel Raynal]

Certain controllers are limited and cannot perform all type of
CHANGE_READ_COLUMN. Let's add a helper that allows checking this.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/nand/raw/nand_base.c | 15 +++++++++++++++
 include/linux/mtd/rawnand.h      |  4 ++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 57a583149cc0..7f29f27bb6fd 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -1312,6 +1312,15 @@ int nand_read_param_page_op(struct nand_chip *chip, u8 page, void *buf,
 int nand_change_read_column_op(struct nand_chip *chip,
 			       unsigned int offset_in_page, void *buf,
 			       unsigned int len, bool force_8bit)
+{
+	return nand_check_change_read_column_op(chip, offset_in_page, buf, len,
+						force_8bit, false);
+}
+
+int nand_check_change_read_column_op(struct nand_chip *chip,
+				     unsigned int offset_in_page, void *buf,
+				     unsigned int len, bool force_8bit,
+				     bool check_only)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
 
@@ -1349,9 +1358,15 @@ int nand_change_read_column_op(struct nand_chip *chip,
 
 		instrs[3].ctx.data.force_8bit = force_8bit;
 
+		if (check_only)
+			return nand_check_op(chip, &op);
+
 		return nand_exec_op(chip, &op);
 	}
 
+	if (check_only)
+		return 0;
+
 	chip->legacy.cmdfunc(chip, NAND_CMD_RNDOUT, offset_in_page, -1);
 	if (len)
 		chip->legacy.read_buf(chip, buf, len);
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index b2f9dd3cbd69..a453386aee70 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -1523,6 +1523,10 @@ int nand_read_page_op(struct nand_chip *chip, unsigned int page,
 int nand_change_read_column_op(struct nand_chip *chip,
 			       unsigned int offset_in_page, void *buf,
 			       unsigned int len, bool force_8bit);
+int nand_check_change_read_column_op(struct nand_chip *chip,
+				     unsigned int offset_in_page, void *buf,
+				     unsigned int len, bool force_8bit,
+				     bool check_only);
 int nand_read_oob_op(struct nand_chip *chip, unsigned int page,
 		     unsigned int offset_in_page, void *buf, unsigned int len);
 int nand_prog_page_begin_op(struct nand_chip *chip, unsigned int page,
-- 
2.27.0