OneNAND: handle byte access on BufferRAM

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index d6c13f7ae5a1..1439c9fa1d23 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -373,6 +373,17 @@ static int onenand_read_bufferram(struct mtd_info *mtd, int area,
 
         bufferram += onenand_bufferram_offset(mtd, area);
 
+        if (ONENAND_CHECK_BYTE_ACCESS(count)) {
+                unsigned short word;
+
+                /* Align with word(16-bit) size */
+                count--;
+
+                /* Read word and save byte */
+                word = this->read_word(bufferram + offset + count);
+                buffer[count] = (word & 0xff);
+        }
+
         memcpy(buffer, bufferram + offset, count);
 
         return 0;
@@ -400,6 +411,17 @@ static int onenand_sync_read_bufferram(struct mtd_info *mtd, int area,
 
         this->mmcontrol(mtd, ONENAND_SYS_CFG1_SYNC_READ);
 
+        if (ONENAND_CHECK_BYTE_ACCESS(count)) {
+                unsigned short word;
+
+                /* Align with word(16-bit) size */
+                count--;
+
+                /* Read word and save byte */
+                word = this->read_word(bufferram + offset + count);
+                buffer[count] = (word & 0xff);
+        }
+
         memcpy(buffer, bufferram + offset, count);
 
         this->mmcontrol(mtd, 0);
@@ -427,6 +449,22 @@ static int onenand_write_bufferram(struct mtd_info *mtd, int area,
 
         bufferram += onenand_bufferram_offset(mtd, area);
 
+        if (ONENAND_CHECK_BYTE_ACCESS(count)) {
+                unsigned short word;
+                int byte_offset;
+
+                /* Align with word(16-bit) size */
+                count--;
+
+                /* Calculate byte access offset */
+                byte_offset = offset + count;
+
+                /* Read word and save byte */
+                word = this->read_word(bufferram + byte_offset);
+                word = (word & ~0xff) | buffer[count];
+                this->write_word(word, bufferram + byte_offset);
+        }
+
         memcpy(bufferram + offset, buffer, count);
 
         return 0;
diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h
index 7419b5fab133..22322c8a7729 100644
--- a/include/linux/mtd/onenand.h
+++ b/include/linux/mtd/onenand.h
@@ -130,6 +130,9 @@ struct onenand_chip {
 #define ONENAND_SET_SYS_CFG1(v, this)                                   \
         (this->write_word(v, this->base + ONENAND_REG_SYS_CFG1))
 
+/* Check byte access in OneNAND */
+#define ONENAND_CHECK_BYTE_ACCESS(addr)         (addr & 0x1)
+
 /*
  * Options bits
  */