Re: [RFC RESEND] serdev binding for QCA7000 UART driver

On Mon, Mar 13, 2017 at 11:16 AM, Stefan Wahren [off-list ref] wrote:

Hi Rob,

since serdev has been merged, i'm currently working on a
suitable ethernet driver for the QCA7000 [1]. In order to provide a plug
and play solution for the network interface i suggest the following
binding, which uses common properties for UART configuration:

* Qualcomm QCA7000 (Ethernet over UART protocol)

Note: The QCA7000 is also useable as a UART slave device.

Should this be s/UART/SPI/ ?

Required properties:
- compatible        : Should be "qca,qca7000-uart"

Optional properties:
- local-mac-address : 6 bytes, Specifies MAC address
- current-speed     : Specifies current serial device speed in
                      bits per second (default = 115200)
- data-bits         : Specifies number of data bits (default = 8)
- use-parity        : If present, this enables the parity
                      error detection (default = off)
- odd-parity        : If present, this specifies that the parity
                      of each character must be odd (default = even)

Example:

/* Freescale i.MX28 UART */
auart0: serial@8006a000 {
    compatible = "fsl,imx28-auart", "fsl,imx23-auart";
    reg = <0x8006a000 0x2000>;
    pinctrl-names = "default";
    pinctrl-0 = <&auart0_2pins_a>;
    status = "okay";

    qca7000: ethernet {
        compatible = "qca,qca7000-uart";
        local-mac-address = [ A0 B0 C0 D0 E0 F0 ];
        current-speed = <38400>;

Unless this device supports auto-baud (generally only AT command set
devices do), this is setup by a bootloader (and you have no way to
reset the device), or the speed changes with different firmware, I
don't think you should need this. Devices typically have a fixed,
initial baudrate that is known, so the driver should know it. Many
devices switch to a higher speed with some command which the driver
should also know. Unless there is some board limitation of the max
speed, then you shouldn't really need a baudrate property. And for max
baudrate, I added "max-speed".

        data-bits = <8>;

Nearly everything uses 8 bits, so this should be the default.

        use-parity;
        odd-parity;

I don't think we need 2 properties here. "even-parity" and
"odd-parity" booleans should be enough to enable and set parity type.

    };
};

Is it okay for you or do you want a different kind of configuration?
Are there any plans for parity handling?

I don't have any. Patches welcome. :)

Rob
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