linux-kernel - Re: [RFC] serial: sc16is7xx: Use DT sub-nodes for UART ports

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Date:   Fri, 10 Aug 2018 11:34:00 -0600
From:   Rob Herring <robh@...nel.org>
To:     Andreas Färber <afaerber@...e.de>
Cc:     "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux-MIPS <linux-mips@...ux-mips.org>, jringle@...dpoint.com,
        Michael Allwright <allsey87@...il.com>,
        Jakub Kicinski <kubakici@...pl>, liuxuenetmail@...il.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] serial: sc16is7xx: Use DT sub-nodes for UART ports

On Sun, Aug 5, 2018 at 5:27 PM Andreas Färber <afaerber@...e.de> wrote:
>
> This is to allow using serdev.
>
> Signed-off-by: Andreas Färber <afaerber@...e.de>
> ---
>  drivers/tty/serial/sc16is7xx.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>
> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> index 243c96025053..ad7267274f65 100644
> --- a/drivers/tty/serial/sc16is7xx.c
> +++ b/drivers/tty/serial/sc16is7xx.c
> @@ -1213,9 +1213,31 @@ static int sc16is7xx_probe(struct device *dev,
>                         SC16IS7XX_IOCONTROL_SRESET_BIT);
>
>         for (i = 0; i < devtype->nr_uart; ++i) {
> +#ifdef CONFIG_OF
> +               struct device_node *np;
> +               struct platform_device *pdev;
> +               char name[6] = "uartx";
> +#endif
> +
>                 s->p[i].line            = i;
>                 /* Initialize port data */
> +#ifdef CONFIG_OF
> +               name[4] = '0' + i;
> +               np = of_get_child_by_name(dev->of_node, name);
> +               if (IS_ERR(np)) {
> +                       ret = PTR_ERR(np);
> +                       goto out_ports;
> +               }
> +               pdev = of_platform_device_create(np, NULL, dev);

Ideally, you would use of_platform_default_populate here. I think
you'd have to add a compatible to the child nodes, but that wouldn't
be a bad thing. I could envision that the child nodes ultimately
become their own driver utilizing the standard 8250 driver and a
compatible string would be needed in that case.

You'd then have to loop over each child of 'dev' instead of the DT nodes.

> +               if (IS_ERR(pdev)) {
> +                       ret = PTR_ERR(pdev);
> +                       goto out_ports;
> +               }
> +               platform_set_drvdata(pdev, dev_get_drvdata(dev));
> +               s->p[i].port.dev        = &pdev->dev;
> +#else
>                 s->p[i].port.dev        = dev;
> +#endif
>                 s->p[i].port.irq        = irq;
>                 s->p[i].port.type       = PORT_SC16IS7XX;
>                 s->p[i].port.fifosize   = SC16IS7XX_FIFO_SIZE;