On Wed, Oct 16, 2024 at 10:56:32AM +0100, Conor Dooley wrote:
> On Mon, Aug 05, 2024 at 10:04:53AM +0200, Linus Walleij wrote:
> > On Tue, Jul 23, 2024 at 1:28 PM Conor Dooley <conor.dooley@xxxxxxxxxxxxx> wrote:
> >
> >
> > > From: Lewis Hanly <lewis.hanly@xxxxxxxxxxxxx>
> > >
> > > Add a driver to support the Polarfire SoC gpio controller
> > >
> > > Signed-off-by: Lewis Hanly <lewis.hanly@xxxxxxxxxxxxx>
> > > Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> >
> > Just a comment on second thought:
> >
> > > +config GPIO_POLARFIRE_SOC
> > > + bool "Microchip FPGA GPIO support"
> > > + depends on OF_GPIO
> > > + select GPIOLIB_IRQCHIP
> >
> > select GPIO_GENERIC?
> >
> > > +static int mpfs_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio_index)
> > > +{
> > > + struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> > > + u32 gpio_cfg;
> > > + unsigned long flags;
> > > +
> > > + raw_spin_lock_irqsave(&mpfs_gpio->lock, flags);
> > > +
> > > + gpio_cfg = readl(mpfs_gpio->base + MPFS_GPIO_CTRL(gpio_index));
> > > + gpio_cfg |= MPFS_GPIO_EN_IN;
> > > + gpio_cfg &= ~(MPFS_GPIO_EN_OUT | MPFS_GPIO_EN_OUT_BUF);
> >
> > OK this part is unique...
> >
> > > +static int mpfs_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio_index, int value)
> > > +{
> > > + struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> > > + u32 gpio_cfg;
> > > + unsigned long flags;
> > > +
> > > + raw_spin_lock_irqsave(&mpfs_gpio->lock, flags);
> > > +
> > > + gpio_cfg = readl(mpfs_gpio->base + MPFS_GPIO_CTRL(gpio_index));
> > > + gpio_cfg |= MPFS_GPIO_EN_OUT | MPFS_GPIO_EN_OUT_BUF;
> >
> > Also here
> >
> > > +static int mpfs_gpio_get_direction(struct gpio_chip *gc,
> > > + unsigned int gpio_index)
> > > +static int mpfs_gpio_get(struct gpio_chip *gc,
> > > + unsigned int gpio_index)
> > > +static void mpfs_gpio_set(struct gpio_chip *gc, unsigned int gpio_index, int value)
> >
> > But these are just MMIO functions.
> >
> > Is it possible to use augmented generic MMIO, i.e just override these
> > two functions that
> > need special handling?
>
> So, I've been looking into this again (finally), with an eye to stripping
> the interrupt handling bits out, and trying to upstream this in pieces.
> I dunno if I'm making a mistake here, but I don't know if there's much
> value in implementing this suggestion - as far as I can tell only the
> get()/set() functions can be replaced by what's provided by gpio-mmio.c.
> There are no controller wide registers that control direction and so
> bgpio_get_dir() can't be used - direction is read from the same
> mpfs_gpio->base + MPFS_GPIO_CTRL(gpio_index) registers that it is set
> using. Adding bgpio stuff, to just go ahead and overwrite it, to save on
> trivial get()/set() implementations seems to me like adding complication
> rather than removing it. What am I missing here?
What does bring a nice simplification though, IMO, is regmap. I am
pretty sure that using it was one of the suggestions made last time
Lewis submitted this - so I think I'm going to do that instead.
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