[RFC PATCH 2/8] mtd: rawnand: ams-delta: Write protect device during probe
From: Boris Brezillon <hidden>
Date: 2018-07-19 06:22:07
Also in:
linux-gpio, linux-omap, lkml
On Thu, 19 Jul 2018 01:57:04 +0200 Janusz Krzysztofik [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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);
Please don't do that until we have a generic way to assert/deassert WP from the core. I agree that we shouldn't write things in the nand_scan() path, but I'd be more comfortable if the core had control on this pin just in case we ever need to disable write-protection during chip detection/initialization.
quoted hunk ↗ jump to hunk
+ /* 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);