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