mtd: nand: Add support to use nand_base poi databuf as bounce buffer

nand_base can be passed a kmap()'d buffers from highmem by
filesystems like jffs2. This results in failure to map the
physical address of the DMA buffer on various contoller
driver on different platforms. This change adds a chip option
to use preallocated databuf as bounce buffers used in
nand_do_read_ops() and nand_do_write_ops().
This allows for specific nand controller driver to set this
option as needed.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 7a922e6c4e4b..2f0af2891f0f 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -176,6 +176,11 @@ typedef enum {
 /* Chip may not exist, so silence any errors in scan */
 #define NAND_SCAN_SILENT_NODEV  0x00040000
 /*
+ * This option could be defined by controller drivers to protect against
+ * kmap'ed, vmalloc'ed highmem buffers being passed from upper layers
+ */
+#define NAND_USE_BOUNCE_BUFFER  0x00080000
+/*
  * Autodetect nand buswidth with readid/onfi.
  * This suppose the driver will configure the hardware in 8 bits mode
  * when calling nand_scan_ident, and update its configuration