[PATCH v6 09/10] dt-binding: mtd: Document gpio-addr-flash

[PATCH v6 09/10] dt-binding: mtd: Document gpio-addr-flash

[Ricardo Ribalda Delgado]

Add documentation for gpio-addr-flash. This binding allow creating
flash devices that are paged using GPIOs.

Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
 .../bindings/mtd/mtd,gpio-addr-flash.txt      | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt

diff --git a/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
new file mode 100644
index 000000000000..304a33880f9e
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
@@ -0,0 +1,25 @@
+Memory Mapped flash with some address lines addressed using GPIOs
+
+Handle the case where a flash device is mostly addressed using physical
+line and supplemented by GPIOs.  This way you can hook up say a 8MiB flash
+to a 2MiB memory range and use the GPIOs to select a particular range.
+
+ - compatible :  must be "mtd,gpio-addr-flash", "cfi-flash";
+ - reg : Address range of the mtd chip that is memory mapped, this is,
+   on the previous example 2MiB.
+ - addr-gpios: List of GPIO specifiers that will be used to address the MSBs
+   address lines. The order goes from LSB to MSB.
+
+For the rest of the properties, see mtd-physmap.txt.
+
+The device tree may optionally contain sub-nodes describing partitions of the
+address space. Check partition.txt for more details.
+
+Example:
+
+	flash@300000 {
+		compatible = "mtd,gpio-addr-flash", "cfi-flash";
+		bank-width = <2>;
+		reg = < 0x00300000 0x00200000 >;
+		addr-gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
+	} ;
-- 
2.19.0

Re: [PATCH v6 09/10] dt-binding: mtd: Document gpio-addr-flash

[Boris Brezillon]

On Thu,  4 Oct 2018 15:01:09 +0200
Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com> wrote:

> Add documentation for gpio-addr-flash. This binding allow creating
> flash devices that are paged using GPIOs.
> 
> Cc: devicetree@vger.kernel.org
> Reviewed-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> ---
>  .../bindings/mtd/mtd,gpio-addr-flash.txt      | 25 +++++++++++++++++++
>  1 file changed, 25 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
> 
> diff --git a/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
> new file mode 100644
> index 000000000000..304a33880f9e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
> @@ -0,0 +1,25 @@
> +Memory Mapped flash with some address lines addressed using GPIOs
> +
> +Handle the case where a flash device is mostly addressed using physical
> +line and supplemented by GPIOs.  This way you can hook up say a 8MiB flash
> +to a 2MiB memory range and use the GPIOs to select a particular range.
> +
> + - compatible :  must be "mtd,gpio-addr-flash", "cfi-flash";

I keep thinking you don't need a specific binding, just add an optional
addr-gpios property to the generic physmap binding and that should do
the trick. Plus, "*mtd*,gpio-addr-flash" is a linux-ism, and DT
bindings should be OS-agnostic.

> + - reg : Address range of the mtd chip that is memory mapped, this is,
> +   on the previous example 2MiB.
> + - addr-gpios: List of GPIO specifiers that will be used to address the MSBs
> +   address lines. The order goes from LSB to MSB.
> +
> +For the rest of the properties, see mtd-physmap.txt.
> +
> +The device tree may optionally contain sub-nodes describing partitions of the
> +address space. Check partition.txt for more details.
> +
> +Example:
> +
> +	flash@300000 {
> +		compatible = "mtd,gpio-addr-flash", "cfi-flash";
> +		bank-width = <2>;
> +		reg = < 0x00300000 0x00200000 >;
> +		addr-gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
> +	} ;

Re: [PATCH v6 09/10] dt-binding: mtd: Document gpio-addr-flash

[Ricardo Ribalda Delgado]

Hi Boris
On Thu, Oct 4, 2018 at 4:02 PM Boris Brezillon
<boris.brezillon@bootlin.com> wrote:
>
> On Thu,  4 Oct 2018 15:01:09 +0200
> Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com> wrote:
>
> > Add documentation for gpio-addr-flash. This binding allow creating
> > flash devices that are paged using GPIOs.
> >
> > Cc: devicetree@vger.kernel.org
> > Reviewed-by: Rob Herring <robh@kernel.org>
> > Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> > ---
> >  .../bindings/mtd/mtd,gpio-addr-flash.txt      | 25 +++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
> >
> > diff --git a/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
> > new file mode 100644
> > index 000000000000..304a33880f9e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mtd/mtd,gpio-addr-flash.txt
> > @@ -0,0 +1,25 @@
> > +Memory Mapped flash with some address lines addressed using GPIOs
> > +
> > +Handle the case where a flash device is mostly addressed using physical
> > +line and supplemented by GPIOs.  This way you can hook up say a 8MiB flash
> > +to a 2MiB memory range and use the GPIOs to select a particular range.
> > +
> > + - compatible :  must be "mtd,gpio-addr-flash", "cfi-flash";
>
> I keep thinking you don't need a specific binding, just add an optional
> addr-gpios property to the generic physmap binding and that should do
> the trick. Plus, "*mtd*,gpio-addr-flash" is a linux-ism, and DT
> bindings should be OS-agnostic.
>

That is a very good point. Please take a look to v10, and tell me what
do you think.

It does not require a specific binding and also it can be build optionally.

Regards!

> > + - reg : Address range of the mtd chip that is memory mapped, this is,
> > +   on the previous example 2MiB.
> > + - addr-gpios: List of GPIO specifiers that will be used to address the MSBs
> > +   address lines. The order goes from LSB to MSB.
> > +
> > +For the rest of the properties, see mtd-physmap.txt.
> > +
> > +The device tree may optionally contain sub-nodes describing partitions of the
> > +address space. Check partition.txt for more details.
> > +
> > +Example:
> > +
> > +     flash@300000 {
> > +             compatible = "mtd,gpio-addr-flash", "cfi-flash";
> > +             bank-width = <2>;
> > +             reg = < 0x00300000 0x00200000 >;
> > +             addr-gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
> > +     } ;
>


-- 
Ricardo Ribalda