mtd: nand: allow drivers to request minimum alignment for passed buffer

In some cases, nand_do_{read,write}_ops is passed with unaligned
ops->datbuf.  Drivers using DMA will be unhappy about unaligned
buffer.

The new struct member, buf_align, represents the minimum alignment
the driver require for the buffer.  If the buffer passed from the
upper MTD layer does not have enough alignment, nand_do_*_ops will
use bufpoi.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c796d0e4039a..ed49a1d634b0 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1954,7 +1954,9 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
                 if (!aligned)
                         use_bufpoi = 1;
                 else if (chip->options & NAND_USE_BOUNCE_BUFFER)
-                        use_bufpoi = !virt_addr_valid(buf);
+                        use_bufpoi = !virt_addr_valid(buf) ||
+                                     !IS_ALIGNED((unsigned long)buf,
+                                                 chip->buf_align);
                 else
                         use_bufpoi = 0;
 
@@ -2810,7 +2812,9 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
                 if (part_pagewr)
                         use_bufpoi = 1;
                 else if (chip->options & NAND_USE_BOUNCE_BUFFER)
-                        use_bufpoi = !virt_addr_valid(buf);
+                        use_bufpoi = !virt_addr_valid(buf) ||
+                                     !IS_ALIGNED((unsigned long)buf,
+                                                 chip->buf_align);
                 else
                         use_bufpoi = 0;
 
@@ -3429,6 +3433,8 @@ static void nand_set_defaults(struct nand_chip *chip)
                 nand_hw_control_init(chip->controller);
         }
 
+        if (!chip->buf_align)
+                chip->buf_align = 1;
 }
 
 /* Sanitize ONFI strings so we can safely print them */