mtd: gpmi: add EDO feature for imx6q

When the frequency on the nand chip pins is above 33MHz,
the nand EDO(extended Data Out) timing could be applied.
The GPMI implements a Feedback read strobe to sample the read data in
the EDO timing mode.

This patch adds the EDO feature for the gpmi-nand driver.

For some onfi nand chips, the mode 4 is the fastest;
while for other onfi nand chips, the mode 5 is the fastest.
This patch only adds the support for the fastest asynchronous timing mode.
So this patch only supports the mode 4 and mode 5.

I tested several Micron's ONFI nand chips with EDO enabled,
take Micron MT29F32G08MAA for example (in mode 5, 100MHz):

1) The test result BEFORE we add the EDO feature:
	=================================================
	mtd_speedtest: MTD device: 2
	mtd_speedtest: MTD device size 209715200, eraseblock size 524288,
				page size 4096, count of eraseblocks 400,
				pages per eraseblock 128, OOB size 218
	.......................................
	mtd_speedtest: testing eraseblock read speed
	mtd_speedtest: eraseblock read speed is 3632 KiB/s
	.......................................
	mtd_speedtest: testing page read speed
	mtd_speedtest: page read speed is 3554 KiB/s
	.......................................
	mtd_speedtest: testing 2 page read speed
	mtd_speedtest: 2 page read speed is 3592 KiB/s
	.......................................
	=================================================

2) The test result AFTER we add the EDO feature:
	=================================================
	mtd_speedtest: MTD device: 2
	mtd_speedtest: MTD device size 209715200, eraseblock size 524288,
				page size 4096, count of eraseblocks 400,
				pages per eraseblock 128, OOB size 218
	.......................................
	mtd_speedtest: testing eraseblock read speed
	mtd_speedtest: eraseblock read speed is 19555 KiB/s
	.......................................
	mtd_speedtest: testing page read speed
	mtd_speedtest: page read speed is 17319 KiB/s
	.......................................
	mtd_speedtest: testing 2 page read speed
	mtd_speedtest: 2 page read speed is 18339 KiB/s
	.......................................
	=================================================

3) The read data performance is much improved by more then 5 times.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index 5c11e761a32e..5b6d546711a6 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -122,6 +122,10 @@ struct nand_timing {
 };
 
 struct gpmi_nand_data {
+	/* flags */
+#define GPMI_ASYNC_EDO_ENABLED	(1 << 0)
+	int			flags;
+
 	/* System Interface */
 	struct device		*dev;
 	struct platform_device	*pdev;
@@ -132,6 +136,7 @@ struct gpmi_nand_data {
 
 	/* Flash Hardware */
 	struct nand_timing	timing;
+	int			timing_mode;
 
 	/* BCH */
 	struct bch_geometry	bch_geometry;
@@ -259,6 +264,7 @@ extern int start_dma_with_bch_irq(struct gpmi_nand_data *,
 
 /* GPMI-NAND helper function library */
 extern int gpmi_init(struct gpmi_nand_data *);
+extern int gpmi_extra_init(struct gpmi_nand_data *);
 extern void gpmi_clear_bch(struct gpmi_nand_data *);
 extern void gpmi_dump_info(struct gpmi_nand_data *);
 extern int bch_set_geometry(struct gpmi_nand_data *);