linux-kernel - Re: [PATCH v4 3/5] mfd: Add RTL8231 core device

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Date:   Thu, 3 Jun 2021 13:58:46 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Sander Vanheule <sander@...nheule.net>
Cc:     Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Michael Walle <michael@...le.cc>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Andrew Lunn <andrew@...n.ch>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 3/5] mfd: Add RTL8231 core device

On Thu, Jun 3, 2021 at 1:01 PM Sander Vanheule <sander@...nheule.net> wrote:
>
> The RTL8231 is implemented as an MDIO device, and provides a regmap
> interface for register access by the core and child devices.
>
> The chip can also be a device on an SMI bus, an I2C-like bus by Realtek.
> Since kernel support for SMI is limited, and no real-world SMI
> implementations have been encountered for this device, this is currently
> unimplemented. The use of the regmap interface should make any future
> support relatively straightforward.
>
> After reset, all pins are muxed to GPIO inputs before the pin drivers
> are enabled. This is done to prevent accidental system resets, when a
> pin is connected to the parent SoC's reset line.
>
> To provide different read and write semantics for the GPIO data
> registers, a secondary virtual register range is used to enable separate
> cacheing properties of pin input and output values.

caching

...


> +static int rtl8231_reg_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +       struct mdio_device *mdio_dev = context;
> +       int ret;
> +
> +       ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr, RTL8231_REAL_REG(reg));
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       *val = ret & 0xffff;
> +
> +       return 0;
> +}
> +
> +static int rtl8231_reg_write(void *context, unsigned int reg, unsigned int val)
> +{
> +       struct mdio_device *mdio_dev = context;
> +
> +       return mdiobus_write(mdio_dev->bus, mdio_dev->addr, RTL8231_REAL_REG(reg), val);
> +}

Hmm... Maybe we can amend regmap-mdio to avoid duplication of the
above? Something like xlate in gpio-regmap or so?

...

> +       mdiodev->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);

Missed

  if (IS_ERR(mdiodev->reset_gpio))
    return PTR_ERR(mdiodev->reset_gpio);

-- 
With Best Regards,
Andy Shevchenko