Re: [PATCH 03/13] pinctrl: add a pincontrol driver for BCM6328

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

On Fri, Aug 19, 2016 at 12:53 PM, Jonas Gorski <jonas.gorski@xxxxxxxxx> wrote:

> Add a pincontrol driver for BCM6328. BCM628 supports muxing 32 pins as
> GPIOs, as LEDs for the integrated LED controller, or various other
> functions. Its pincontrol mux registers also control other aspects, like
> switching the second USB port between host and device mode.
>
> Signed-off-by: Jonas Gorski <jonas.gorski@xxxxxxxxx>

This looks good. Just thinking following the other patches
that maybe this should be a syscon child driver.

> +#define BCM6328_NGPIO          32

I wonder why the pin control driver cares about that?

> +struct bcm6328_pinctrl {
> +       struct pinctrl_dev *pctldev;
> +       struct pinctrl_desc desc;
> +
> +       void __iomem *mode;
> +       void __iomem *mux[3];
> +
> +       /* register access lock */
> +       spinlock_t lock;
> +
> +       struct gpio_chip gpio;

Usually this should be the other way around: the gpio_chip
knows about the pin controller, the pin controller does not
know about the gpio_chip.

I don't see it used in the code either? Artifact?

> +static void bcm6328_rmw_mux(struct bcm6328_pinctrl *pctl, unsigned pin,
> +                           u32 mode, u32 mux)
> +{
> +       unsigned long flags;
> +       u32 reg;
> +
> +       spin_lock_irqsave(&pctl->lock, flags);
> +       if (pin < 32) {
> +               reg = __raw_readl(pctl->mode);
> +               reg &= ~BIT(pin);
> +               if (mode)
> +                       reg |= BIT(pin);
> +               __raw_writel(reg, pctl->mode);
> +       }
> +
> +       reg = __raw_readl(pctl->mux[pin / 16]);
> +       reg &= ~(3UL << (pin % 16));
> +       reg |= mux << (pin % 16);
> +       __raw_writel(reg, pctl->mux[pin / 16]);
> +
> +       spin_unlock_irqrestore(&pctl->lock, flags);
> +}

Why all this __raw_* accessors? What is wrong with readl_relaxed()
and writel_relaxed()? Or MIPS doesn't have them?

> +#ifdef CONFIG_OF
> +       .dt_node_to_map         = pinconf_generic_dt_node_to_map_pin,
> +       .dt_free_map            = pinctrl_utils_free_map,
> +#endif

Nice, but why not just add
depends on OF
to the Kconfig and get rid of the #ifdef?

> +static int bcm6328_pinctrl_probe(struct platform_device *pdev)
> +{
> +       struct bcm6328_pinctrl *pctl;
> +       struct resource *res;
> +       void __iomem *mode, *mux;
> +
> +       res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mode");
> +       mode = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(mode))
> +               return PTR_ERR(mode);
> +
> +       res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mux");
> +       mux = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(mux))
> +               return PTR_ERR(mux);

This mishmash of remap windows makes me prefer the syscon
design pattern.

Yours,
Linus Walleij
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