[PATCH 1/2] mtd: physmap_of: Add read-only fallback

[PATCH 1/2] mtd: physmap_of: Add read-only fallback

[Aaron Sierra]

From: Joe Schultz <jschultz@xes-inc.com>

Previously, when probing a CFI chip which was write-protected at the
hardware level, the probe would fail due to the fact it could not put
the chip into QUERY mode. This would result in no MTD devices being
created.

Add a fallback to probe using the map_rom driver if the user-selected
probe fails.

Signed-off-by: Joe Schultz <jschultz@xes-inc.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
---
 drivers/mtd/maps/physmap_of.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c
index c62e1c3..efbf416 100644
--- a/drivers/mtd/maps/physmap_of.c
+++ b/drivers/mtd/maps/physmap_of.c
@@ -272,6 +272,16 @@ static int of_flash_probe(struct platform_device *dev)
 			info->list[i].mtd = obsolete_probe(dev,
 							   &info->list[i].map);
 		}
+
+		/* Fall back to mapping region as ROM */
+		if (!info->list[i].mtd) {
+			dev_warn(&dev->dev,
+				"do_map_probe() failed for type %s\n",
+				 probe_type);
+
+			info->list[i].mtd = do_map_probe("map_rom",
+							 &info->list[i].map);
+		}
 		mtd_list[i] = info->list[i].mtd;
 
 		err = -ENXIO;
-- 
1.9.1

Re: [PATCH 1/2] mtd: physmap_of: Add read-only fallback

[Brian Norris]

An old one, but I'm curious...

On Thu, Sep 25, 2014 at 12:20:08PM -0500, Aaron Sierra wrote:
> From: Joe Schultz <jschultz@xes-inc.com>
> 
> Previously, when probing a CFI chip which was write-protected at the
> hardware level, the probe would fail due to the fact it could not put
> the chip into QUERY mode. This would result in no MTD devices being
> created.
> 
> Add a fallback to probe using the map_rom driver if the user-selected
> probe fails.

Why can't the user just select map_rom instead?

Brian

> Signed-off-by: Joe Schultz <jschultz@xes-inc.com>
> Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
> ---
>  drivers/mtd/maps/physmap_of.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c
> index c62e1c3..efbf416 100644
> --- a/drivers/mtd/maps/physmap_of.c
> +++ b/drivers/mtd/maps/physmap_of.c
> @@ -272,6 +272,16 @@ static int of_flash_probe(struct platform_device *dev)
>  			info->list[i].mtd = obsolete_probe(dev,
>  							   &info->list[i].map);
>  		}
> +
> +		/* Fall back to mapping region as ROM */
> +		if (!info->list[i].mtd) {
> +			dev_warn(&dev->dev,
> +				"do_map_probe() failed for type %s\n",
> +				 probe_type);
> +
> +			info->list[i].mtd = do_map_probe("map_rom",
> +							 &info->list[i].map);
> +		}
>  		mtd_list[i] = info->list[i].mtd;
>  
>  		err = -ENXIO;
> -- 
> 1.9.1
> 

Re: [PATCH 1/2] mtd: physmap_of: Add read-only fallback

[Aaron Sierra]

----- Original Message -----
> From: "Brian Norris" <computersforpeace@gmail.com>
> Sent: Tuesday, December 16, 2014 8:37:00 PM
> 
> An old one, but I'm curious...
> 
> On Thu, Sep 25, 2014 at 12:20:08PM -0500, Aaron Sierra wrote:
> > From: Joe Schultz <jschultz@xes-inc.com>
> > 
> > Previously, when probing a CFI chip which was write-protected at the
> > hardware level, the probe would fail due to the fact it could not put
> > the chip into QUERY mode. This would result in no MTD devices being
> > created.
> > 
> > Add a fallback to probe using the map_rom driver if the user-selected
> > probe fails.
> 
> Why can't the user just select map_rom instead?

Brian, that isn't an ideal requirement in our situation. Our single-board
computers can become read-only for all onboard non-volatile storage based
on a signal from the outside world (a backplane most often). We find it
helpful to be able to use a single device tree that works in read-write
and read-only environments.

-Aaron

> > Signed-off-by: Joe Schultz <jschultz@xes-inc.com>
> > Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
> > ---
> >  drivers/mtd/maps/physmap_of.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c
> > index c62e1c3..efbf416 100644
> > --- a/drivers/mtd/maps/physmap_of.c
> > +++ b/drivers/mtd/maps/physmap_of.c
> > @@ -272,6 +272,16 @@ static int of_flash_probe(struct platform_device *dev)
> >  			info->list[i].mtd = obsolete_probe(dev,
> >  							   &info->list[i].map);
> >  		}
> > +
> > +		/* Fall back to mapping region as ROM */
> > +		if (!info->list[i].mtd) {
> > +			dev_warn(&dev->dev,
> > +				"do_map_probe() failed for type %s\n",
> > +				 probe_type);
> > +
> > +			info->list[i].mtd = do_map_probe("map_rom",
> > +							 &info->list[i].map);
> > +		}
> >  		mtd_list[i] = info->list[i].mtd;
> >  
> >  		err = -ENXIO;
> > --
> > 1.9.1
> > 
> 

Re: [PATCH 1/2] mtd: physmap_of: Add read-only fallback

[Brian Norris]

On Thu, Sep 25, 2014 at 12:20:08PM -0500, Aaron Sierra wrote:
> From: Joe Schultz <jschultz@xes-inc.com>
> 
> Previously, when probing a CFI chip which was write-protected at the
> hardware level, the probe would fail due to the fact it could not put
> the chip into QUERY mode. This would result in no MTD devices being
> created.
> 
> Add a fallback to probe using the map_rom driver if the user-selected
> probe fails.
> 
> Signed-off-by: Joe Schultz <jschultz@xes-inc.com>
> Signed-off-by: Aaron Sierra <asierra@xes-inc.com>

Pushed to l2-mtd.git. Thanks!

Brian