mtd: OMAP: Enable GPMC prefetch mode

Enable GPMC's prefetch feature for NAND access. This speeds up NAND read
access a lot by pre-fetching contents in the background and reading them
through the FIFO address.

The current implementation has two limitations:

 a) it only works in 8-bit mode
 b) it only supports read access

Both is easily fixable by someone who has hardware to implement it.

Note that U-Boot code uses non word-aligned buffers to read data into, and
request read lengths that are not multiples of 4, so both partial buffers
(head and tail) have to be addressed.

Tested on AM335x hardware.

Tested-by: Guido Martínez <guido@vanguardiasur.com.ar>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>
Signed-off-by: Daniel Mack <zonque@gmail.com>
[trini: Make apply again, use 'cs' fix pointed out by Guido]
Signed-off-by: Tom Rini <trini@ti.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/mtd/omap_gpmc.h b/include/linux/mtd/omap_gpmc.h
index 9a86582..6cbae45 100644
--- a/include/linux/mtd/omap_gpmc.h
+++ b/include/linux/mtd/omap_gpmc.h
@@ -66,7 +66,11 @@ struct gpmc {
 	u32 status;		/* 0x54 */
 	u8 res5[0x8];		/* 0x58 */
 	struct gpmc_cs cs[8];	/* 0x60, 0x90, .. */
-	u8 res6[0x14];		/* 0x1E0 */
+	u32 prefetch_config1;	/* 0x1E0 */
+	u32 prefetch_config2;	/* 0x1E4 */
+	u32 res6;		/* 0x1E8 */
+	u32 prefetch_control;	/* 0x1EC */
+	u32 prefetch_status;	/* 0x1F0 */
 	u32 ecc_config;		/* 0x1F4 */
 	u32 ecc_control;	/* 0x1F8 */
 	u32 ecc_size_config;	/* 0x1FC */