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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>
This commit is contained in:
Nicolas Pitre 2009-05-31 22:25:40 -04:00 committed by David Woodhouse
parent 9dbc090274
commit bfee1a4311
1 changed files with 23 additions and 0 deletions
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23
drivers/mtd/nand/orion_nand.c
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@ -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)