mtd: spinand: Allow enabling Octal DTR mode in the core

Enable Octal DTR SPI mode, i.e. 8D-8D-8D mode, if the SPI NAND flash
device supports it. Mixed OSPI (1S-1S-8S & 1S-8S-8S), mixed DTR modes
(1S-1D-8D), etc. aren't supported yet.

The method to switch to Octal DTR SPI mode may vary across
manufacturers. For example, for Winbond, it is enabled by writing
values to the volatile configuration register. So, let the
manufacturer's code have their own implementation for switching to
Octal DTR SPI mode.

Check for the SPI NAND device's support for Octal DTR mode using
spinand flags, and if the data_ops and ctrl_ops are 8D-8D-8D, call
change_mode() manufacturer op. If the SPI controller doesn't
supports these modes, the selected data_ops and ctrl_ops will
prevent switching to the Octal DTR mode. And finally update the
spinand protocol and ctrl_ops on success.

Signed-off-by: Apurva Nandan <a-nandan@ti.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
index 2486b43fe2..1bc9cb9d54 100644
--- a/drivers/mtd/nand/spi/core.c
+++ b/drivers/mtd/nand/spi/core.c
@@ -950,6 +950,57 @@ spinand_select_ctrl_ops_variant(struct spinand_device *spinand,
 	return NULL;
 }
 
+static bool spinand_op_is_octal_dtr(const struct spi_mem_op *op)
+{
+	return  op->cmd.buswidth == 8 && op->cmd.dtr &&
+		op->addr.buswidth == 8 && op->addr.dtr &&
+		op->data.buswidth == 8 && op->data.dtr;
+}
+
+static int spinand_init_octal_dtr_enable(struct spinand_device *spinand)
+{
+	struct udevice *dev = spinand->slave->dev;
+	const struct spinand_ctrl_ops *octal_dtr_ctrl_ops;
+	int ret;
+
+	if (!(spinand->flags & SPINAND_HAS_OCTAL_DTR_BIT))
+		return 0;
+
+	if (!(spinand_op_is_octal_dtr(spinand->data_ops.read_cache) &&
+	      spinand_op_is_octal_dtr(spinand->data_ops.write_cache) &&
+	      spinand_op_is_octal_dtr(spinand->data_ops.update_cache)))
+		return 0;
+
+	octal_dtr_ctrl_ops = spinand_select_ctrl_ops_variant(spinand,
+					spinand->desc_entry->ctrl_ops_variants,
+					SPINAND_8D);
+
+	if (!octal_dtr_ctrl_ops)
+		return 0;
+
+	if (!spinand->manufacturer->ops->change_protocol) {
+		dev_info(dev,
+			 "Missing ->change_mode(), unable to switch mode\n");
+		return -EOPNOTSUPP;
+	}
+
+	ret = spinand->manufacturer->ops->change_protocol(spinand, SPINAND_8D);
+	if (ret) {
+		dev_err(dev,
+			"Failed to enable Octal DTR SPI mode (err = %d)\n",
+			ret);
+		return ret;
+	}
+
+	spinand->protocol = SPINAND_8D;
+	spinand->ctrl_ops = octal_dtr_ctrl_ops;
+
+	dev_dbg(dev,
+		"%s SPI NAND switched to Octal DTR SPI (8D-8D-8D) mode\n",
+		spinand->manufacturer->name);
+	return 0;
+}
+
 /**
  * spinand_match_and_init() - Try to find a match between a device ID and an
  *			      entry in a spinand_info table
@@ -1139,6 +1190,10 @@ static int spinand_init(struct spinand_device *spinand)
 			goto err_free_bufs;
 	}
 
+	ret = spinand_init_octal_dtr_enable(spinand);
+	if (ret)
+		goto err_manuf_cleanup;
+
 	ret = nanddev_init(nand, &spinand_ops, THIS_MODULE);
 	if (ret)
 		goto err_manuf_cleanup;