On Thu, 2021-06-03 at 13:58 +0300, Andy Shevchenko wrote:
> On Thu, Jun 3, 2021 at 1:01 PM Sander Vanheule <sander@xxxxxxxxxxxxx> 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?
>
I wanted to make the masking explicit, but since regmap-mdio currently requires
a register address width of 5 bit, it could move there.
Actually, can we safely assume that any MDIO driver implementing clause-22
access (5-bit register address width) will just ignore higher bits? In that
case, I could just drop these functions and not even modify regmap-mdio. It
appears to work for bitbanged MDIO.
> > + 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);
>
Will fix.
Best,
Sander
