[RFC PATCH 2/8] mtd: rawnand: ams-delta: Write protect device during probe

Janusz Krzysztofik
2018-07-18T23:57:04Z

Initialize NWP GPIO pin low to protect the device from hazard during
probe. Release write protection as soon as the device is under
control.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
---
drivers/mtd/nand/raw/ams-delta.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index 48233d638d2a..6ac38e9cfa1a 100644
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -219,8 +219,8 @@ static int ams_delta_init(struct platform_device *pdev)

platform_set_drvdata(pdev, priv);

- /* Set chip enabled, but */
- priv->gpiod_nwp = devm_gpiod_get(&pdev->dev, "nwp", GPIOD_OUT_HIGH);
+ /* Set chip enabled but write protected */
+ priv->gpiod_nwp = devm_gpiod_get(&pdev->dev, "nwp", GPIOD_OUT_LOW);
if (IS_ERR(priv->gpiod_nwp)) {
err = PTR_ERR(priv->gpiod_nwp);
dev_err(&pdev->dev, "NWP GPIO request failed (%d)\n", err);
@@ -267,6 +267,9 @@ static int ams_delta_init(struct platform_device *pdev)
if (err)
goto out_mtd;

+ /* As soon as the device is found, release write protection */
+ gpiod_set_value(priv->gpiod_nwp, 1);
+
/* Register the partitions */
mtd_device_register(mtd, partition_info, ARRAY_SIZE(partition_info));

@@ -288,6 +291,9 @@ static int ams_delta_cleanup(struct platform_device *pdev)
struct mtd_info *mtd = nand_to_mtd(&priv->nand_chip);
void __iomem *io_base = priv->io_base;

+ /* Apply write protection */
+ gpiod_set_value(priv->gpiod_nwp, 0);
+
/* Release resources, unregister device */
nand_release(mtd);

--
2.16.4