[MTD] [OneNAND] 2X program support

The 2X Program is an extension of Program Operation.

Since the device is equipped with two DataRAMs, and two-plane NAND Flash 
memory array, these two component enables simultaneous program of 4KiB.
Plane1 has only even blocks such as block0, block2, block4 while Plane2 
has only odd blocks such as block1, block3, block5.
So MTD regards it as 4KiB page size and 256KiB block size

Now the following chips support it. (KFXXX16Q2M)
Demux: KFG2G16Q2M, KFH4G16Q2M, KFW8G16Q2M,
Mux:   KFM2G16Q2M, KFN4G16Q2M,

And more recent chips

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

4 files changed, 144 insertions, 27 deletions

diff --git a/drivers/mtd/onenand/Kconfig b/drivers/mtd/onenand/Kconfig
index c257d397d08a..64ec034c43c5 100644
--- a/drivers/mtd/onenand/Kconfig
+++ b/drivers/mtd/onenand/Kconfig
@@ -40,4 +40,20 @@ config MTD_ONENAND_OTP
 
           OTP block is fully-guaranteed to be a valid block.
 
+config MTD_ONENAND_2X_PROGRAM
+        bool "OneNAND 2X program support"
+        help
+          The 2X Program is an extension of Program Operation.
+          Since the device is equipped with two DataRAMs, and two-plane NAND
+          Flash memory array, these two component enables simultaneous program
+          of 4KiB. Plane1 has only even blocks such as block0, block2, block4
+          while Plane2 has only odd blocks such as block1, block3, block5.
+          So MTD regards it as 4KiB page size and 256KiB block size
+
+          Now the following chips support it. (KFXXX16Q2M)
+            Demux: KFG2G16Q2M, KFH4G16Q2M, KFW8G16Q2M,
+            Mux:   KFM2G16Q2M, KFN4G16Q2M,
+
+          And more recent chips
+
 endif # MTD_ONENAND
diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index 0537fac8de74..7d194cfdb873 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -206,6 +206,15 @@ static int onenand_command(struct mtd_info *mtd, int cmd, loff_t addr, size_t le
         default:
                 block = (int) (addr >> this->erase_shift);
                 page = (int) (addr >> this->page_shift);
+
+                if (ONENAND_IS_2PLANE(this)) {
+                        /* Make the even block number */
+                        block &= ~1;
+                        /* Is it the odd plane? */
+                        if (addr & this->writesize)
+                                block++;
+                        page >>= 1;
+                }
                 page &= this->page_mask;
                 break;
         }
@@ -216,8 +225,12 @@ static int onenand_command(struct mtd_info *mtd, int cmd, loff_t addr, size_t le
                 value = onenand_bufferram_address(this, block);
                 this->write_word(value, this->base + ONENAND_REG_START_ADDRESS2);
 
-                /* Switch to the next data buffer */
-                ONENAND_SET_NEXT_BUFFERRAM(this);
+                if (ONENAND_IS_2PLANE(this))
+                        /* It is always BufferRAM0 */
+                        ONENAND_SET_BUFFERRAM0(this);
+                else
+                        /* Switch to the next data buffer */
+                        ONENAND_SET_NEXT_BUFFERRAM(this);
 
                 return 0;
         }
@@ -247,6 +260,8 @@ static int onenand_command(struct mtd_info *mtd, int cmd, loff_t addr, size_t le
                         break;
 
                 default:
+                        if (ONENAND_IS_2PLANE(this) && cmd == ONENAND_CMD_PROG)
+                                cmd = ONENAND_CMD_2X_PROG;
                         dataram = ONENAND_CURRENT_BUFFERRAM(this);
                         break;
                 }
@@ -445,8 +460,9 @@ static inline int onenand_bufferram_offset(struct mtd_info *mtd, int area)
         struct onenand_chip *this = mtd->priv;
 
         if (ONENAND_CURRENT_BUFFERRAM(this)) {
+                /* Note: the 'this->writesize' is a real page size */
                 if (area == ONENAND_DATARAM)
-                        return mtd->writesize;
+                        return this->writesize;
                 if (area == ONENAND_SPARERAM)
                         return mtd->oobsize;
         }
@@ -572,6 +588,30 @@ static int onenand_write_bufferram(struct mtd_info *mtd, int area,
 }
 
 /**
+ * onenand_get_2x_blockpage - [GENERIC] Get blockpage at 2x program mode
+ * @param mtd           MTD data structure
+ * @param addr          address to check
+ * @return              blockpage address
+ *
+ * Get blockpage address at 2x program mode
+ */
+static int onenand_get_2x_blockpage(struct mtd_info *mtd, loff_t addr)
+{
+        struct onenand_chip *this = mtd->priv;
+        int blockpage, block, page;
+
+        /* Calculate the even block number */
+        block = (int) (addr >> this->erase_shift) & ~1;
+        /* Is it the odd plane? */
+        if (addr & this->writesize)
+                block++;
+        page = (int) (addr >> (this->page_shift + 1)) & this->page_mask;
+        blockpage = (block << 7) | page;
+
+        return blockpage;
+}
+
+/**
  * onenand_check_bufferram - [GENERIC] Check BufferRAM information
  * @param mtd           MTD data structure
  * @param addr          address to check
@@ -585,7 +625,10 @@ static int onenand_check_bufferram(struct mtd_info *mtd, loff_t addr)
         int blockpage, found = 0;
         unsigned int i;
 
-        blockpage = (int) (addr >> this->page_shift);
+        if (ONENAND_IS_2PLANE(this))
+                blockpage = onenand_get_2x_blockpage(mtd, addr);
+        else
+                blockpage = (int) (addr >> this->page_shift);
 
         /* Is there valid data? */
         i = ONENAND_CURRENT_BUFFERRAM(this);
@@ -625,7 +668,10 @@ static void onenand_update_bufferram(struct mtd_info *mtd, loff_t addr,
         int blockpage;
         unsigned int i;
 
-        blockpage = (int) (addr >> this->page_shift);
+        if (ONENAND_IS_2PLANE(this))
+                blockpage = onenand_get_2x_blockpage(mtd, addr);
+        else
+                blockpage = (int) (addr >> this->page_shift);
 
         /* Invalidate another BufferRAM */
         i = ONENAND_NEXT_BUFFERRAM(this);
@@ -734,6 +780,7 @@ static int onenand_read(struct mtd_info *mtd, loff_t from, size_t len,
         int read = 0, column;
         int thislen;
         int ret = 0, boundary = 0;
+        int writesize = this->writesize;
 
         DEBUG(MTD_DEBUG_LEVEL3, "onenand_read: from = 0x%08x, len = %i\n", (unsigned int) from, (int) len);
 
@@ -754,22 +801,22 @@ static int onenand_read(struct mtd_info *mtd, loff_t from, size_t len,
         /* Do first load to bufferRAM */
         if (read < len) {
                 if (!onenand_check_bufferram(mtd, from)) {
-                        this->command(mtd, ONENAND_CMD_READ, from, mtd->writesize);
+                        this->command(mtd, ONENAND_CMD_READ, from, writesize);
                         ret = this->wait(mtd, FL_READING);
                         onenand_update_bufferram(mtd, from, !ret);
                 }
         }
 
-        thislen = min_t(int, mtd->writesize, len - read);
-        column = from & (mtd->writesize - 1);
-        if (column + thislen > mtd->writesize)
+        thislen = min_t(int, writesize, len - read);
+        column = from & (writesize - 1);
+        if (column + thislen > writesize)