mtd: orion_nand: use burst reads with double word accesses

This is not 8 times faster than byte access, but still around 60% faster.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/mtd/nand/orion_nand.c b/drivers/mtd/nand/orion_nand.c
index c2dfd3ea353..7ad972229db 100644
--- a/drivers/mtd/nand/orion_nand.c
+++ b/drivers/mtd/nand/orion_nand.c
@@ -47,6 +47,28 @@ static void orion_nand_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl
         writeb(cmd, nc->IO_ADDR_W + offs);
 }
 
+static void orion_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
+{
+        struct nand_chip *chip = mtd->priv;
+        void __iomem *io_base = chip->IO_ADDR_R;
+        uint64_t *buf64;
+        int i = 0;
+
+        while (len && (unsigned long)buf & 7) {
+                *buf++ = readb(io_base);
+                len--;
+        }
+        buf64 = (uint64_t *)buf;
+        while (i < len/8) {
+                uint64_t x;
+                asm ("ldrd\t%0, [%1]" : "=r" (x) : "r" (io_base));
+                buf64[i++] = x;
+        }
+        i *= 8;
+        while (i < len)
+                buf[i++] = readb(io_base);
+}
+
 static int __init orion_nand_probe(struct platform_device *pdev)
 {
         struct mtd_info *mtd;
@@ -83,6 +105,7 @@ static int __init orion_nand_probe(struct platform_device *pdev)
         nc->priv = board;
         nc->IO_ADDR_R = nc->IO_ADDR_W = io_base;
         nc->cmd_ctrl = orion_nand_cmd_ctrl;
+        nc->read_buf = orion_nand_read_buf;
         nc->ecc.mode = NAND_ECC_SOFT;
 
         if (board->chip_delay)