[PATCH v2 2/2] mtd: rawnand: arasan: Fix clock rate in NV-DDR

[Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>]

From: Olga Kitaina <okitain@gmail.com>

According to the Arasan NAND controller spec, the flash clock rate for SDR
must be <= 100 MHz, while for NV-DDR it must be the same as the rate of the
CLK line for the mode. The driver previously always set 100 MHz for NV-DDR,
which would result in incorrect behavior for NV-DDR modes 0-4.

The appropriate clock rate can be calculated from the NV-DDR timing
parameters as 1/tCK, or for rates measured in picoseconds,
10^12 / nand_nvddr_timings->tCK_min.

Signed-off-by: Olga Kitaina <okitain@gmail.com>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>
---
 drivers/mtd/nand/raw/arasan-nand-controller.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/arasan-nand-controller.c b/drivers/mtd/nand/raw/arasan-nand-controller.c
index 4f6da82dd2b1..0eff069d7f80 100644
--- a/drivers/mtd/nand/raw/arasan-nand-controller.c
+++ b/drivers/mtd/nand/raw/arasan-nand-controller.c
@@ -1044,10 +1044,20 @@ static int anfc_setup_interface(struct nand_chip *chip, int target,
 				 DQS_BUFF_SEL_OUT(dqs_mode);
 	}
 
-	ret = clk_set_rate(nfc->bus_clk, ANFC_XLNX_SDR_DFLT_CORE_CLK);
-	if (ret) {
-		dev_err(nfc->dev, "Failed to change bus clock rate\n");
-		return ret;
+	if (nand_interface_is_sdr(conf)) {
+		ret = clk_set_rate(nfc->bus_clk, ANFC_XLNX_SDR_DFLT_CORE_CLK);
+		if (ret) {
+			dev_err(nfc->dev, "Failed to change bus clock rate\n");
+			return ret;
+		}
+	} else {
+		/* ONFI timings are defined in picoseconds */
+		ret = clk_set_rate(nfc->bus_clk, div_u64((u64)NSEC_PER_SEC * 1000,
+							 conf->timings.nvddr.tCK_min));
+		if (ret) {
+			dev_err(nfc->dev, "Failed to change bus clock rate\n");
+			return ret;
+		}
 	}
 
 	/*
-- 
2.17.1