[RFC,2/8] mtd: rawnand: ams-delta: Write protect device during probe
diff mbox series

Message ID 20180718235710.18242-3-jmkrzyszt@gmail.com
State New
Headers show
Series
  • mtd: rawnand: ams-delta: Use gpio-omap accessors for data I/O
Related show

Commit Message

Janusz Krzysztofik July 18, 2018, 11:57 p.m. UTC
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(-)

Comments

Boris Brezillon July 19, 2018, 6:22 a.m. UTC | #1
On Thu, 19 Jul 2018 01:57:04 +0200
Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:

> 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.

> +
>  	/* 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);
>  

--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Janusz Krzysztofik July 20, 2018, 6:02 p.m. UTC | #2
On Thursday, July 19, 2018 8:22:00 AM CEST Boris Brezillon wrote:
> On Thu, 19 Jul 2018 01:57:04 +0200
> Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:
> 
> > 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.

OK, I can drop this patch for now if that's what you suggest.
 
Thanks,
Janusz


--
To unsubscribe from this list: send the line "unsubscribe linux-gpio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch
diff mbox series

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);