On Sun, Aug 02, 2020 at 07:46:26PM +0200, Christian Eggers wrote:

Convert the binding document for at25 EEPROMs from txt to yaml. The
compatible property doesn't use a regex pattern (as in at24), because
the 'vendor' and the 'model' are an "infinite" list (even if only 5
combinations are found in the current dts files). The settings required
by a driver are given as separate properties.

Signed-off-by: Christian Eggers <ceggers@arri.de>
---
On Friday, Jul 31 2020, Rob Herring wrote:

quoted

quoted

On Tue, Jul 28, 2020 at 1:34 AM Christian Eggers [off-list ref] wrote:
When I specify

  compatible:
    enum:
      - atmel,at25

I get an error in dt_binding_check:
...

You can do:

items:
  - {}
  - const: atmel,at25

But really, the possible compatible strings need to be listed out. See
at24.yaml as it had similar issues IIRC.

I think that at24 is very diffrent from at25 here (at least the linux
driver). Whilst the at24 driver extracts parameters of the chip from the
'model' part, at25 gets this information from separate properties.

As there is virtually an infinite list of possible vendors and products
for such type of hardware, is there any value to use expressions like in
the at24 binding?

Maybe so, but there are only 4 compatible strings to document in the 
tree. That's not a lot to cover and we already have some of them in 
free-form text. If the infinite number becomes a problem we can always 
address that later. I'm sure that less than infinite buyers/products 
will prevent infinite producers.

So it is much less a mess compared to at24.

Other question: What is the meaning of the maintainers field in the
binding? 

Someone who knows the h/w and can review binding changes. 

Is it related to the binding itself or the linux driver? 
I am
not the maintainer of the driver...

Doesn't have to be the same person.

Fix this.

This doesn't work for 'atmel,at25' alone. You'll need a 'oneOf' with a 
single entry.

+    description:
+      'Should be "<vendor>,<chip>", and generic value "atmel,at25".
+      Example "<vendor>,<chip>" values:
+        "anvo,anv32e61w"
+        "microchip,25lc040"
+        "st,m95m02"
+        "st,m95256"'
+
+  reg:
+    description:
+      Chip select number.
+
+  spi-max-frequency:
+    $ref: /schemas/types.yaml#definitions/uint32

This is common and already has a definition. Just need 'true'.

+    description:
+      Maximum SPI frequency to use.
+
+  pagesize:
+    $ref: /schemas/types.yaml#definitions/uint32
+    description:
+      Size of the eeprom page.

Constraints? I'd assume it's some power of 2 set.

+
+  size:
+    $ref: /schemas/types.yaml#definitions/uint32
+    description:
+      Total eeprom size in bytes.
+
+  address-width:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [ 8, 9, 16, 24 ]
+    description:
+      Number of address bits.
+      For 9 bits, the MSB of the address is sent as bit 3 of the instruction
+      byte, before the address byte.
+
+  spi-cpha: true
+
+  spi-cpol: true
+
+  read-only:
+    description:
+      Disable writes to the eeprom.
+    type: boolean
+
+  wp-gpios:
+    maxItems: 1
+    description:
+      GPIO to which the write-protect pin of the chip is connected.
+
+  # Deprecated: at25,byte-len, at25,addr-mode, at25,page-size
+  at25,byte-len:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+       Total eeprom size in bytes. Deprecated, use "size" property instead.
+    deprecated: true
+
+  at25,addr-mode:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+       Addr-mode flags, as defined in include/linux/spi/eeprom.h.
+       Deprecated, use "address-width" property instead.
+    deprecated: true
+
+  at25,page-size:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Size of the eeprom page. Deprecated, use "pagesize" property instead.
+    deprecated: true
+
+required:
+  - compatible
+  - reg
+  - spi-max-frequency
+  - pagesize
+  - size
+  - address-width
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    spi0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        eeprom@0 {
+            compatible = "st,m95256", "atmel,at25";
+            reg = <0>;
+            spi-max-frequency = <5000000>;
+            spi-cpha;
+            spi-cpol;
+            wp-gpios = <&gpio1 3 0>;
+
+            pagesize = <64>;
+            size = <32768>;
+            address-width = <16>;
+        };
+    };
-- 
Christian Eggers
Embedded software developer

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