mtd: rawnand: ams-delta: Don't hardcode read/write pulse widths

Instead of forcing Amstrad Delta specific read/write pulse widths, use
variables initialised from respective fields of chip SDR timings.
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200212003929.6682-8-jmkrzyszt@gmail.com

drivers/mtd/nand/raw/ams-delta.c

@@ -40,12 +40,14 @@ struct ams_delta_nand {
 	struct gpio_desc	*gpiod_cle;
 	struct gpio_descs	*data_gpiods;
 	bool			data_in;
+	unsigned int		tRP;
+	unsigned int		tWP;
 };
 
 static void ams_delta_write_commit(struct ams_delta_nand *priv)
 {
 	gpiod_set_value(priv->gpiod_nwe, 1);
-	ndelay(40);
+	ndelay(priv->tWP);
 	gpiod_set_value(priv->gpiod_nwe, 0);
 }
 
@@ -82,7 +84,7 @@ static u8 ams_delta_io_read(struct ams_delta_nand *priv)
 	DECLARE_BITMAP(values, BITS_PER_TYPE(res)) = { 0, };
 
 	gpiod_set_value(priv->gpiod_nre, 1);
-	ndelay(40);
+	ndelay(priv->tRP);
 
 	gpiod_get_raw_array_value(data_gpiods->ndescs, data_gpiods->desc,
 				  data_gpiods->info, values);
@@ -187,8 +189,31 @@ static int ams_delta_exec_op(struct nand_chip *this,
 	return ret;
 }
 
+static int ams_delta_setup_data_interface(struct nand_chip *this, int csline,
+					  const struct nand_data_interface *cf)
+{
+	struct ams_delta_nand *priv = nand_get_controller_data(this);
+	const struct nand_sdr_timings *sdr = nand_get_sdr_timings(cf);
+	struct device *dev = &nand_to_mtd(this)->dev;
+
+	if (IS_ERR(sdr))
+		return PTR_ERR(sdr);
+
+	if (csline == NAND_DATA_IFACE_CHECK_ONLY)
+		return 0;
+
+	priv->tRP = DIV_ROUND_UP(sdr->tRP_min, 1000);
+	dev_dbg(dev, "using %u ns read pulse width\n", priv->tRP);
+
+	priv->tWP = DIV_ROUND_UP(sdr->tWP_min, 1000);
+	dev_dbg(dev, "using %u ns write pulse width\n", priv->tWP);
+
+	return 0;
+}
+
 static const struct nand_controller_ops ams_delta_ops = {
 	.exec_op = ams_delta_exec_op,
+	.setup_data_interface = ams_delta_setup_data_interface,
 };
 
 /*