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Date:   Mon, 11 May 2020 22:50:42 +0300
From:   Serge Semin <Sergey.Semin@baikalelectronics.ru>
To:     Rob Herring <robh@kernel.org>
CC:     Serge Semin <fancer.lancer@gmail.com>,
        Jarkko Nikula <jarkko.nikula@linux.intel.com>,
        Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Paul Burton <paulburton@kernel.org>,
        Ralf Baechle <ralf@linux-mips.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Wolfram Sang <wsa@the-dreams.de>,
        Frank Rowand <frowand.list@gmail.com>,
        <linux-mips@vger.kernel.org>, <linux-i2c@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 02/12] dt-bindings: i2c: Convert DW I2C binding to DT
 schema
Message-ID: <20200511195042.zqd45ckwwdbk4qnr@mobilestation>
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On Mon, May 11, 2020 at 11:09:24AM -0500, Rob Herring wrote:
> On Sun, May 10, 2020 at 12:50:08PM +0300, Serge Semin wrote:
> > Modern device tree bindings are supposed to be created as YAML-files
> > in accordance with dt-schema. This commit replaces Synopsys DW I2C
> > legacy bare text bindings with YAML file. As before the bindings file
> > states that the corresponding dts node is supposed to be compatible
> > either with generic DW I2C controller or with Microsemi Ocelot SoC I2C
> > one, to have registers, interrupts and clocks properties. In addition
> > the node may have clock-frequency, i2c-sda-hold-time-ns,
> > i2c-scl-falling-time-ns and i2c-sda-falling-time-ns optional properties.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> > Cc: Paul Burton <paulburton@kernel.org>
> > Cc: Ralf Baechle <ralf@linux-mips.org>
> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Cc: Wolfram Sang <wsa@the-dreams.de>
> > Cc: Frank Rowand <frowand.list@gmail.com>
> > Cc: linux-mips@vger.kernel.org
> > 
> > ---
> > 
> > Changelog v2:
> > - Make sure that "mscc,ocelot-i2c" compatible node may have up to two
> >   registers space defined, while normal DW I2C controller will have only
> >   one registers space.
> > - Add "mscc,ocelot-i2c" example to test the previous fix.
> > - Declare "unevaluatedProperties" property instead of
> >   "additionalProperties" one.
> > - Due to the previous fix we can now discard the dummy boolean properties
> >   definitions, since the proper type evaluation will be performed by the
> >   generic i2c-controller.yaml schema.
> > ---
> >  .../bindings/i2c/i2c-designware.txt           |  73 ---------
> >  .../bindings/i2c/snps,designware-i2c.yaml     | 154 ++++++++++++++++++
> >  2 files changed, 154 insertions(+), 73 deletions(-)
> >  delete mode 100644 Documentation/devicetree/bindings/i2c/i2c-designware.txt
> >  create mode 100644 Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > deleted file mode 100644
> > index 08be4d3846e5..000000000000
> > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> > +++ /dev/null
> > @@ -1,73 +0,0 @@
> > -* Synopsys DesignWare I2C
> > -
> > -Required properties :
> > -
> > - - compatible : should be "snps,designware-i2c"
> > -                or "mscc,ocelot-i2c" with "snps,designware-i2c" for fallback
> > - - reg : Offset and length of the register set for the device
> > - - interrupts : <IRQ> where IRQ is the interrupt number.
> > - - clocks : phandles for the clocks, see the description of clock-names below.
> > -   The phandle for the "ic_clk" clock is required. The phandle for the "pclk"
> > -   clock is optional. If a single clock is specified but no clock-name, it is
> > -   the "ic_clk" clock. If both clocks are listed, the "ic_clk" must be first.
> > -
> > -Recommended properties :
> > -
> > - - clock-frequency : desired I2C bus clock frequency in Hz.
> > -
> > -Optional properties :
> > -
> > - - clock-names : Contains the names of the clocks:
> > -    "ic_clk", for the core clock used to generate the external I2C clock.
> > -    "pclk", the interface clock, required for register access.
> > -
> > - - reg : for "mscc,ocelot-i2c", a second register set to configure the SDA hold
> > -   time, named ICPU_CFG:TWI_DELAY in the datasheet.
> > -
> > - - i2c-sda-hold-time-ns : should contain the SDA hold time in nanoseconds.
> > -   This option is only supported in hardware blocks version 1.11a or newer and
> > -   on Microsemi SoCs ("mscc,ocelot-i2c" compatible).
> > -
> > - - i2c-scl-falling-time-ns : should contain the SCL falling time in nanoseconds.
> > -   This value which is by default 300ns is used to compute the tLOW period.
> > -
> > - - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
> > -   This value which is by default 300ns is used to compute the tHIGH period.
> > -
> > -Examples :
> > -
> > -	i2c@f0000 {
> > -		#address-cells = <1>;
> > -		#size-cells = <0>;
> > -		compatible = "snps,designware-i2c";
> > -		reg = <0xf0000 0x1000>;
> > -		interrupts = <11>;
> > -		clock-frequency = <400000>;
> > -	};
> > -
> > -	i2c@1120000 {
> > -		#address-cells = <1>;
> > -		#size-cells = <0>;
> > -		compatible = "snps,designware-i2c";
> > -		reg = <0x1120000 0x1000>;
> > -		interrupt-parent = <&ictl>;
> > -		interrupts = <12 1>;
> > -		clock-frequency = <400000>;
> > -		i2c-sda-hold-time-ns = <300>;
> > -		i2c-sda-falling-time-ns = <300>;
> > -		i2c-scl-falling-time-ns = <300>;
> > -	};
> > -
> > -	i2c@1120000 {
> > -		#address-cells = <1>;
> > -		#size-cells = <0>;
> > -		reg = <0x2000 0x100>;
> > -		clock-frequency = <400000>;
> > -		clocks = <&i2cclk>;
> > -		interrupts = <0>;
> > -
> > -		eeprom@64 {
> > -			compatible = "linux,slave-24c02";
> > -			reg = <0x40000064>;
> > -		};
> > -	};
> > diff --git a/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml b/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml
> > new file mode 100644
> > index 000000000000..8d4e5fccbd1c
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/i2c/snps,designware-i2c.yaml
> > @@ -0,0 +1,154 @@
> > +# SPDX-License-Identifier: GPL-2.0-only
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/i2c/snps,designware-i2c.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Synopsys DesignWare APB I2C Controller
> > +
> > +maintainers:
> > +  - Jarkko Nikula <jarkko.nikula@linux.intel.com>
> > +
> > +allOf:
> > +  - $ref: /schemas/i2c/i2c-controller.yaml#
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          not:
> > +            contains:
> > +              const: mscc,ocelot-i2c
> > +    then:
> > +      properties:
> > +        reg:
> > +          maxItems: 1
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - description: Generic Synopsys DesignWare I2C controller
> > +        const: snps,designware-i2c
> > +      - description: Microsemi Ocelot SoCs I2C controller
> > +        items:
> > +          - const: mscc,ocelot-i2c
> > +          - const: snps,designware-i2c
> > +
> > +  reg:
> > +    minItems: 1
> > +    items:
> > +      - description: DW APB I2C controller memory mapped registers
> > +      - description: |
> > +          ICPU_CFG:TWI_DELAY registers to setup the SDA hold time.
> > +          This registers are specific to the Ocelot I2C-controller.
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  clocks:
> > +    minItems: 1
> > +    items:
> > +      - description: I2C controller reference clock source
> > +      - description: APB interface clock source
> > +
> > +  clock-names:
> > +    minItems: 1
> > +    items:
> > +      - const: ref
> > +      - const: pclk
> > +
> > +  resets:
> > +    maxItems: 1
> > +
> > +  clock-frequency:
> > +    description: Desired I2C bus clock frequency in Hz
> > +    enum: [100000, 400000, 1000000, 3400000]
> > +    default: 400000
> > +
> > +  i2c-sda-hold-time-ns:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> Don't need a type ref as properties with a unit-suffix already have one.

Ok. Seeing "-ns" suffixed properties have uint32-array type I'll have to add the
restriction "maxItems: 1" here then.

> 
> > +    description: |
> > +      The property should contain the SDA hold time in nanoseconds. This option
> > +      is only supported in hardware blocks version 1.11a or newer or on
> > +      Microsemi SoCs.
> > +
> > +  i2c-scl-falling-time-ns:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: |
> > +      The property should contain the SCL falling time in nanoseconds.
> > +      This value is used to compute the tLOW period.
> > +    default: 300
> > +
> > +  i2c-sda-falling-time-ns:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: |
> > +      The property should contain the SDA falling time in nanoseconds.
> > +      This value is used to compute the tHIGH period.
> > +    default: 300
> > +
> > +  dmas:
> > +    items:
> > +      - description: TX DMA Channel
> > +      - description: RX DMA Channel
> > +
> > +  dma-names:
> > +    items:
> > +      - const: tx
> > +      - const: rx
> > +
> > +unevaluatedProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - "#address-cells"
> > +  - "#size-cells"
> > +  - interrupts
> > +
> > +examples:
> > +  - |
> > +    i2c@f0000 {
> > +      compatible = "snps,designware-i2c";
> > +      reg = <0xf0000 0x1000>;
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +      interrupts = <11>;
> > +      clock-frequency = <400000>;
> > +    };
> > +  - |
> > +    i2c@1120000 {
> > +      compatible = "snps,designware-i2c";
> > +      reg = <0x1120000 0x1000>;
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +      interrupts = <12 1>;
> > +      clock-frequency = <400000>;
> > +      i2c-sda-hold-time-ns = <300>;
> > +      i2c-sda-falling-time-ns = <300>;
> > +      i2c-scl-falling-time-ns = <300>;
> > +    };
> > +  - |
> > +    i2c@2000 {
> > +      compatible = "snps,designware-i2c";
> > +      reg = <0x2000 0x100>;
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +      clock-frequency = <400000>;
> > +      clocks = <&i2cclk>;
> > +      interrupts = <0>;
> > +
> > +      eeprom@64 {
> > +        compatible = "linux,slave-24c02";
> > +        reg = <0x40000064>;
> 
> This causes 'make dt_binding_check' to fail. The unit-address should be 
> '40000064'. However, there's a bug in dtc not liking the high bits set 
> either. There's a fix pending, but I'd just fix the example here to 
> avoid the issue. 

Do you mean a fix suggested in this patchset or someplace else? I've submitted
it before this patch so to solve the problem you've discovered.

Regarding the example. Do you suggest to completely remove the eeprom
sub-node? I am asking because without proper reg flags setting the i2c-slave
mode example would be just wrong.

-Sergey

> 
> > +      };
> > +    };
> > +  - |
> > +    i2c@100400 {
> > +      compatible = "mscc,ocelot-i2c", "snps,designware-i2c";
> > +      reg = <0x100400 0x100>, <0x198 0x8>;
> > +      pinctrl-0 = <&i2c_pins>;
> > +      pinctrl-names = "default";
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +      interrupts = <8>;
> > +      clocks = <&ahb_clk>;
> > +    };
> > +...
> > -- 
> > 2.25.1
> >