[PATCH 8/8] dt-binding: mtd: Document gpio-addr-flash

[PATCH 8/8] 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
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
 .../bindings/mtd/gpio-addr-flash.txt          | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt

diff --git a/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
new file mode 100644
index 000000000000..4279e8cad09b
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
@@ -0,0 +1,46 @@
+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 : "cfi-gpio-addr-flash"
+ - reg : Address range of the mtd chip that is memory mapped, this is,
+   on the previous example 2MiB.
+ - bank-width : Width (in bytes) of the bank.  Equal to the
+   device width times the number of interleaved chips.
+ - probe-type : (optional) "cfi_probe", "jedec_probe". How the mtd chip
+   is going to be probed. If omitted, assumed to be equal to "cfi_probe".
+ - #address-cells, #size-cells : Must be present if the device has
+   sub-nodes representing partitions (see below).  In this case
+   both #address-cells and #size-cells must be equal to 1.
+
+The device tree may optionally contain sub-nodes describing partitions of the
+address space. See partition.txt for more detail.
+
+Example:
+
+	cfi_flash_0: cfi_flash {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "cfi-gpio-addr-flash";
+		bank-width = <2>;
+		reg = < 0x00300000 0x00200000 >;
+		gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
+		partition@0 {
+			reg = < 0x0 0x200000 >;
+			label = "Golden Bitstream";
+		};
+		partition@200000 {
+			reg = < 0x200000 0x200000 >;
+			label = "User Bitstream";
+		};
+		partition@400000 {
+			reg = < 0x400000 0x200000 >;
+			label = "V4L Controls";
+		};
+		partition@600000 {
+			reg = < 0x600000 0x200000 >;
+			label = "Production Data";
+		};
+	} ;
-- 
2.18.0

Re: [PATCH 8/8] dt-binding: mtd: Document gpio-addr-flash

[Rob Herring]

On Tue, Aug 21, 2018 at 04:31:52PM +0200, Ricardo Ribalda Delgado wrote:
> Add documentation for gpio-addr-flash. This binding allow creating
> flash devices that are paged using GPIOs.
> 
> Cc: devicetree@vger.kernel.org
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> ---
>  .../bindings/mtd/gpio-addr-flash.txt          | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> 
> diff --git a/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> new file mode 100644
> index 000000000000..4279e8cad09b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> @@ -0,0 +1,46 @@
> +Memory Mapped flash with some address lines addressed using GPIOs

That's ugly...

> +
> +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 : "cfi-gpio-addr-flash"

Why a new compatible? Shouldn't just adding some address gpios to an 
existing flash device binding be sufficient?

> + - reg : Address range of the mtd chip that is memory mapped, this is,
> +   on the previous example 2MiB.
> + - bank-width : Width (in bytes) of the bank.  Equal to the
> +   device width times the number of interleaved chips.
> + - probe-type : (optional) "cfi_probe", "jedec_probe". How the mtd chip
> +   is going to be probed. If omitted, assumed to be equal to "cfi_probe".
> + - #address-cells, #size-cells : Must be present if the device has
> +   sub-nodes representing partitions (see below).  In this case
> +   both #address-cells and #size-cells must be equal to 1.
> +
> +The device tree may optionally contain sub-nodes describing partitions of the
> +address space. See partition.txt for more detail.
> +
> +Example:
> +
> +	cfi_flash_0: cfi_flash {
> +		#address-cells = <1>;
> +		#size-cells = <1>;
> +		compatible = "cfi-gpio-addr-flash";
> +		bank-width = <2>;
> +		reg = < 0x00300000 0x00200000 >;
> +		gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
> +		partition@0 {
> +			reg = < 0x0 0x200000 >;
> +			label = "Golden Bitstream";
> +		};
> +		partition@200000 {
> +			reg = < 0x200000 0x200000 >;
> +			label = "User Bitstream";
> +		};
> +		partition@400000 {
> +			reg = < 0x400000 0x200000 >;
> +			label = "V4L Controls";
> +		};
> +		partition@600000 {
> +			reg = < 0x600000 0x200000 >;
> +			label = "Production Data";
> +		};
> +	} ;
> -- 
> 2.18.0
> 

Re: [PATCH 8/8] dt-binding: mtd: Document gpio-addr-flash

[Ricardo Ribalda Delgado]

 aHi Robb
On Fri, Aug 31, 2018 at 2:17 PM Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Aug 21, 2018 at 04:31:52PM +0200, Ricardo Ribalda Delgado wrote:
> > Add documentation for gpio-addr-flash. This binding allow creating
> > flash devices that are paged using GPIOs.
> >
> > Cc: devicetree@vger.kernel.org
> > Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
> > ---
> >  .../bindings/mtd/gpio-addr-flash.txt          | 46 +++++++++++++++++++
> >  1 file changed, 46 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> >
> > diff --git a/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> > new file mode 100644
> > index 000000000000..4279e8cad09b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
> > @@ -0,0 +1,46 @@
> > +Memory Mapped flash with some address lines addressed using GPIOs
>
> That's ugly...
>
If hw was perfect there would be no firmware engineers in the world :P

> > +
> > +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 : "cfi-gpio-addr-flash"
>
> Why a new compatible? Shouldn't just adding some address gpios to an
> existing flash device binding be sufficient?

Because today there are handled by two different drivers

Thanks!

>
> > + - reg : Address range of the mtd chip that is memory mapped, this is,
> > +   on the previous example 2MiB.
> > + - bank-width : Width (in bytes) of the bank.  Equal to the
> > +   device width times the number of interleaved chips.
> > + - probe-type : (optional) "cfi_probe", "jedec_probe". How the mtd chip
> > +   is going to be probed. If omitted, assumed to be equal to "cfi_probe".
> > + - #address-cells, #size-cells : Must be present if the device has
> > +   sub-nodes representing partitions (see below).  In this case
> > +   both #address-cells and #size-cells must be equal to 1.
> > +
> > +The device tree may optionally contain sub-nodes describing partitions of the
> > +address space. See partition.txt for more detail.
> > +
> > +Example:
> > +
> > +     cfi_flash_0: cfi_flash {
> > +             #address-cells = <1>;
> > +             #size-cells = <1>;
> > +             compatible = "cfi-gpio-addr-flash";
> > +             bank-width = <2>;
> > +             reg = < 0x00300000 0x00200000 >;
> > +             gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
> > +             partition@0 {
> > +                     reg = < 0x0 0x200000 >;
> > +                     label = "Golden Bitstream";
> > +             };
> > +             partition@200000 {
> > +                     reg = < 0x200000 0x200000 >;
> > +                     label = "User Bitstream";
> > +             };
> > +             partition@400000 {
> > +                     reg = < 0x400000 0x200000 >;
> > +                     label = "V4L Controls";
> > +             };
> > +             partition@600000 {
> > +                     reg = < 0x600000 0x200000 >;
> > +                     label = "Production Data";
> > +             };
> > +     } ;
> > --
> > 2.18.0
> >



-- 
Ricardo Ribalda