mtd: nand: sunxi: Set serial access mode correctly

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=d052e508a4069f0711ea68156f4b1565bf14c41c
Commit:     d052e508a4069f0711ea68156f4b1565bf14c41c
Parent:     9c618292dba6aa9b82e8a2e4e6fe70f54bd87a81
Author:     Roy Spliet <r.spliet at ultimaker.com>
AuthorDate: Fri Jun 26 11:00:11 2015 +0200
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Mon Jul 20 10:45:53 2015 -0700

    mtd: nand: sunxi: Set serial access mode correctly
    
    Replaces the hard coded "always use EDO" policy with that prescribed
    by the ONFI 3.1 specification that EDO mode should always be used if tRC
    is below 30ns.
    
    Signed-off-by: Roy Spliet <r.spliet at ultimaker.com>
    Acked-by: Boris Brezillon <boris.brezillon at free-electrons.com>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/nand/sunxi_nand.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index 663e331..f97a58d 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -99,6 +99,9 @@
 				 NFC_CMD_INT_ENABLE | \
 				 NFC_DMA_INT_ENABLE)
 
+/* define bit use in NFC_TIMING_CTL */
+#define NFC_TIMING_CTL_EDO	BIT(8)
+
 /* define NFC_TIMING_CFG register layout */
 #define NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD)		\
 	(((tWB) & 0x3) | (((tADL) & 0x3) << 2) |		\
@@ -225,6 +228,7 @@ struct sunxi_nand_chip {
 	struct mtd_info mtd;
 	unsigned long clk_rate;
 	u32 timing_cfg;
+	u32 timing_ctl;
 	int selected;
 	int nsels;
 	struct sunxi_nand_chip_sel sels[0];
@@ -411,6 +415,7 @@ static void sunxi_nfc_select_chip(struct mtd_info *mtd, int chip)
 		}
 	}
 
+	writel(sunxi_nand->timing_ctl, nfc->regs + NFC_REG_TIMING_CTL);
 	writel(sunxi_nand->timing_cfg, nfc->regs + NFC_REG_TIMING_CFG);
 	writel(ctl, nfc->regs + NFC_REG_CTL);
 
@@ -940,6 +945,13 @@ static int sunxi_nand_chip_set_timings(struct sunxi_nand_chip *chip,
 	/* TODO: A83 has some more bits for CDQSS, CS, CLHZ, CCS, WC */
 	chip->timing_cfg = NFC_TIMING_CFG(tWB, tADL, tWHR, tRHW, tCAD);
 
+	/*
+	 * ONFI specification 3.1, paragraph 4.15.2 dictates that EDO data
+	 * output cycle timings shall be used if the host drives tRC less than
+	 * 30 ns.
+	 */
+	chip->timing_ctl = (timings->tRC_min < 30000) ? NFC_TIMING_CTL_EDO : 0;
+
 	/* Convert min_clk_period from picoseconds to nanoseconds */
 	min_clk_period = DIV_ROUND_UP(min_clk_period, 1000);
 
@@ -1441,11 +1453,6 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, nfc);
 
-	/*
-	 * TODO: replace this magic value with EDO flag
-	 */
-	writel(0x100, nfc->regs + NFC_REG_TIMING_CTL);
-
 	ret = sunxi_nand_chips_init(dev, nfc);
 	if (ret) {
 		dev_err(dev, "failed to init nand chips\n");