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@ultimaker.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index 663e3314bb83d89937fcb7c5f49a280dad6e3994..f97a58d6aae1bbbacdb29ca86ac30c1f21d19e48 100644 (file)
--- 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");