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Subject: Re: [PATCH v10 1/2] dt-bindings: spi: Add schema for Cadence QSPI
 Controller driver
To:     Vignesh Raghavendra <vigneshr@ti.com>,
        Rob Herring <robh+dt@kernel.org>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-spi <linux-spi@vger.kernel.org>,
        Mark Brown <broonie@kernel.org>,
        simon.k.r.goldschmidt@gmail.com, Dinh Nguyen <dinguyen@kernel.org>,
        tien.fong.chee@intel.com,
        =?UTF-8?Q?Marek_Va=c5=a1ut?= <marex@denx.de>,
        cheol.yong.kim@intel.com, qi-ming.wu@intel.com
References: <20200219022852.28065-1-vadivel.muruganx.ramuthevar@linux.intel.com>
 <20200219022852.28065-2-vadivel.muruganx.ramuthevar@linux.intel.com>
 <CAL_JsqKJky=y4nhECUFVzTYvEpjFoOH_6UY9uZG5bvBVWq=SYQ@mail.gmail.com>
 <64b7ab12-0c11-df25-95e7-ee62227ec7ec@linux.intel.com>
 <85178128-4906-8b1a-e3f1-ab7a36ff8c23@ti.com>
From:   "Ramuthevar, Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>
Message-ID: <c119a70d-b7ef-ab1b-4590-7ac77395297f@linux.intel.com>
Date:   Tue, 25 Feb 2020 15:38:12 +0800
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Hi,

On 25/2/2020 2:41 PM, Vignesh Raghavendra wrote:
>
> On 25/02/20 11:54 am, Ramuthevar, Vadivel MuruganX wrote:
>> Hi Rob,
>>
>>       Thank you for the review comments...
>>
>> On 24/2/2020 11:54 PM, Rob Herring wrote:
>>> On Tue, Feb 18, 2020 at 8:29 PM Ramuthevar,Vadivel MuruganX
>>> <vadivel.muruganx.ramuthevar@linux.intel.com> wrote:
>>>> From: Ramuthevar Vadivel Murugan
>>>> <vadivel.muruganx.ramuthevar@linux.intel.com>
>>> Cc the DT list if you want this reviewed.
>> Sorry,  next patch will add DT list in CC.
>>>> Add dt-bindings documentation for Cadence-QSPI controller to support
>>>> spi based flash memories.
>>>>
>>>> Signed-off-by: Ramuthevar Vadivel Murugan
>>>> <vadivel.muruganx.ramuthevar@linux.intel.com>
>>>> ---
>>>>    .../devicetree/bindings/spi/cdns,qspi-nor.yaml     | 147
>>>> +++++++++++++++++++++
>>>>    1 file changed, 147 insertions(+)
>>>>    create mode 100644
>>>> Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
>>>> b/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
>>>> new file mode 100644
>>>> index 000000000000..1a4d6e8d0d0b
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
>>>> @@ -0,0 +1,147 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: "http://devicetree.org/schemas/spi/cdns,qspi-nor.yaml#"
>>>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>>>> +
>>>> +title: Cadence QSPI Flash Controller support
>>>> +
>>>> +maintainers:
>>>> +  - Ramuthevar Vadivel Murugan
>>>> <vadivel.muruganx.ramuthevar@linux.intel.com>
>>>> +
>>>> +allOf:
>>>> +  - $ref: "spi-controller.yaml#"
>>>> +
>>>> +description: |
>>>> +  Binding Documentation for Cadence QSPI controller,This controller is
>>>> +  present in the Intel LGM, Altera SoCFPGA and TI SoCs and this driver
>>>> +  has been tested On Intel's LGM SoC.
>>>> +
>>>> +  - compatible : should be one of the following:
>>>> +        Generic default - "cdns,qspi-nor".
>>>> +        For TI 66AK2G SoC - "ti,k2g-qspi", "cdns,qspi-nor".
>>>> +        For TI AM654 SoC  - "ti,am654-ospi", "cdns,qspi-nor".
>>>> +        For Intel LGM SoC - "intel,lgm-qspi", "cdns,qspi-nor".
>>>> +
>>>> +properties:
>>>> +  compatible:
>>>> +    oneOf:
>>>> +      - items:
>>>> +        - enum:
>>>> +           - ti,k2g-qspi
>>>> +        - const: cdns,qspi-nor
>>>> +
>>>> +      - items:
>>>> +        - enum:
>>>> +           - ti,am654-ospi
>>>> +        - const: cdns,qspi-nor
>>>> +
>>>> +      - items:
>>>> +        - enum:
>>>> +           - intel,lgm-qspi
>>>> +        - const: cdns,qspi-nor
>>>> +
>>>> +      - items:
>>>> +        - const: cdns,qspi-nor
>>>> +
>>>> +  reg:
>>>> +    maxItems: 2
>>>> +
>>>> +  interrupts:
>>>> +    maxItems: 1
>>>> +
>>>> +  clocks:
>>>> +    maxItems: 1
>>>> +
>>>> +  cdns,fifo-depth:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description:
>>>> +      Size of the data FIFO in words.
>>> A 4GB fifo is valid? Add some constraints.
>> 128 is valid, will update.
> Nope, the width of this field is 8bits -> 256 bytes 

correct me if I am wrong, the width of this field is 4bits -> 128 bytes 
(based on QUAD mode) .

>>>> +
>>>> +  cdns,fifo-width:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description:
>>>> +      Bus width of the data FIFO in bytes.
>>> Add some constraints.
>> 4 is valid , will fix it.
>>>> +
>>>> +  cdns,trigger-address:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description:
>>>> +      32-bit indirect AHB trigger address.
>>>> +
>>>> +  cdns,rclk-en:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description: |
>>>> +      Flag to indicate that QSPI return clock is used to latch the
>>>> read data
>>>> +      rather than the QSPI clock. Make sure that QSPI return clock
>>>> is populated
>>>> +      on the board before using this property.
>>>> +
>>>> +# subnode's properties
>>>> +patternProperties:
>>>> +  "^.*@[0-9a-fA-F]+$":
>>>> +    type: object
>>>> +    description:
>>>> +      flash device uses the subnodes below defined properties.
>>>> +
>>>> +  cdns,read-delay:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description:
>>>> +      Delay for read capture logic, in clock cycles.
>>> 4 billion clock delay is valid?
>> based on the ref_clk , will add it.
>>>> +
>>>> +  cdns,tshsl-ns:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>> You can drop this, anything with a standard unit suffix already has a
>>> type.
>> sure , will drop it.
>>>> +    description: |
>>>> +      Delay in nanoseconds for the length that the master mode chip
>>>> select
>>>> +      outputs are de-asserted between transactions.
>>> Constraints...?
>> 50ns, will add it.
>>
> This really depends on the input clk:
>
> Clock Delay for Chip Select Deassert:
>
> Delay in master reference clocks for the length that the master mode
>
> chip select outputs are de-asserted between transactions The
>
> minimum delay is always SCLK period to ensure the chip select is
>
> never re-asserted within an SCLK period.
>
> I don't see a easy way of verifying constraints in yaml.
>
> Same applies for below 3 properties as well.

Thank you vignesh for  the detailed explanation.

Regards
Vadivel
> Regards
> Vignesh
>
>> Regards
>> Vadivel
>>>> +
>>>> +  cdns,tsd2d-ns:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description: |
>>>> +      Delay in nanoseconds between one chip select being de-activated
>>>> +      and the activation of another.
>>>> +
>>>> +  cdns,tchsh-ns:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description: |
>>>> +      Delay in nanoseconds between last bit of current transaction and
>>>> +      deasserting the device chip select (qspi_n_ss_out).
>>>> +
>>>> +  cdns,tslch-ns:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    description: |
>>>> +      Delay in nanoseconds between setting qspi_n_ss_out low and
>>>> +      first bit transfer.
>>>> +
>>>> +required:
>>>> +  - compatible
>>>> +  - reg
>>>> +  - interrupts
>>>> +  - clocks
>>>> +  - cdns,fifo-depth
>>>> +  - cdns,fifo-width
>>>> +  - cdns,trigger-address
>>>> +
>>>> +examples:
>>>> +  - |
>>>> +    qspi: spi@ff705000 {
>>>> +          compatible = "cdns,qspi-nor";
>>>> +          #address-cells = <1>;
>>>> +          #size-cells = <0>;
>>>> +          reg = <0xff705000 0x1000>,
>>>> +                <0xffa00000 0x1000>;
>>>> +          interrupts = <0 151 4>;
>>>> +          clocks = <&qspi_clk>;
>>>> +          cdns,fifo-depth = <128>;
>>>> +          cdns,fifo-width = <4>;
>>>> +          cdns,trigger-address = <0x00000000>;
>>>> +
>>>> +          flash0: n25q00@0 {
>>>> +              compatible = "jedec,spi-nor";
>>>> +              reg = <0x0>;
>>>> +              cdns,read-delay = <4>;
>>>> +              cdns,tshsl-ns = <50>;
>>>> +              cdns,tsd2d-ns = <50>;
>>>> +              cdns,tchsh-ns = <4>;
>>>> +              cdns,tslch-ns = <4>;
>>>> +          };
>>>> +    };
>>>> +
>>>> -- 
>>>> 2.11.0
>>>>