[PATCH] mtd: rawnand: denali: deassert write protect pin

Masahiro Yamada yamada.masahiro at socionext.com
Thu May 7 15:12:00 CEST 2020

[ Linux commit 9afbe7c0140f663586edb6e823b616bd7076c00a ]

If the write protect signal from this IP is connected to the NAND
device, this IP can handle the WP# pin via the WRITE_PROTECT

The Denali NAND Flash Memory Controller User's Guide describes
this register like follows:

  When the controller is in reset, the WP# pin is always asserted
  to the device. Once the reset is removed, the WP# is de-asserted.
  The software will then have to come and program this bit to
  assert/de-assert the same.

    1 - Write protect de-assert
    0 - Write protect assert

The default value is 1, so the write protect is de-asserted after
the reset is removed. The driver can write to the device unless
someone has explicitly cleared register before booting the kernel.

The boot ROM of some UniPhier SoCs (LD4, Pro4, sLD8, Pro5) is the
case; the boot ROM clears the WRITE_PROTECT register when the system
is booting from the NAND device, so the NAND device becomes read-only.

Set it to 1 in the driver in order to allow the write access to the

Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>

 drivers/mtd/nand/raw/denali.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
index b525b1be54..f00f6c39e1 100644
--- a/drivers/mtd/nand/raw/denali.c
+++ b/drivers/mtd/nand/raw/denali.c
@@ -1089,6 +1089,7 @@ static void denali_hw_init(struct denali_nand_info *denali)
 	iowrite32(CHIP_EN_DONT_CARE__FLAG, denali->reg + CHIP_ENABLE_DONT_CARE);
 	iowrite32(0xffff, denali->reg + SPARE_AREA_MARKER);
+	iowrite32(WRITE_PROTECT__FLAG, denali->reg + WRITE_PROTECT);
 int denali_calc_ecc_bytes(int step_size, int strength)

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