nvmem: imx-ocotp: Ensure WAIT bits are preserved when setting timing

[ Upstream commit 0493c4792b4eb260441e57f52cc11a9ded48b5a7 ]

The i.MX6 and i.MX8 both have a bit-field spanning bits 27:22 called the
WAIT field.

The WAIT field according to the documentation for both parts "specifies
time interval between auto read and write access in one time program. It is
given in number of ipg_clk periods."

This patch ensures that the relevant field is read and written back to the
timing register.

Fixes: 0642bac7 ("nvmem: imx-ocotp: add write support")
Signed-off-by: NBryan O'Donoghue <pure.logic@nexus-software.ie>
Reviewed-by: NLeonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/nvmem/imx-ocotp.c

@@ -189,7 +189,8 @@ static void imx_ocotp_set_imx6_timing(struct ocotp_priv *priv)
 	strobe_prog = clk_rate / (1000000000 / 10000) + 2 * (DEF_RELAX + 1) - 1;
 	strobe_read = clk_rate / (1000000000 / 40) + 2 * (DEF_RELAX + 1) - 1;
 
-	timing = strobe_prog & 0x00000FFF;
+	timing = readl(priv->base + IMX_OCOTP_ADDR_TIMING) & 0x0FC00000;
+	timing |= strobe_prog & 0x00000FFF;
 	timing |= (relax       << 12) & 0x0000F000;
 	timing |= (strobe_read << 16) & 0x003F0000;