linux-kernel - Re: [PATCH v2 2/5] pinctrl: renesas: pinctrl-rzg2l: Add helper functions to read/write pin config

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Message-ID: <CAMuHMdUG4A26kBP_8fbraYxVOhtR5GZuwZyO8z6X5a8K6hmmYg@mail.gmail.com>
Date:   Mon, 8 Nov 2021 16:32:51 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Prabhakar <prabhakar.csengg@...il.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH v2 2/5] pinctrl: renesas: pinctrl-rzg2l: Add helper
 functions to read/write pin config

Hi Prabhakar,

On Fri, Oct 29, 2021 at 2:44 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> Add helper functions to read/read modify write pin config.
>
> Switch to use helper functions for pins supporting PIN_CONFIG_INPUT_ENABLE
> capabilities.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@...renesas.com>

Thanks for your patch!

> --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> @@ -91,6 +91,8 @@
>  #define SD_CH(n)               (0x3000 + (n) * 4)
>  #define QSPI                   (0x3008)
>
> +#define PORT_PIN_CFG_OFFSET    0x80

This definition belongs in [PATCH v2 5/5].

> +
>  #define PVDD_1800              1       /* I/O domain voltage <= 1.8V */
>  #define PVDD_3300              0       /* I/O domain voltage >= 3.3V */
>
> @@ -424,6 +426,52 @@ static int rzg2l_dt_node_to_map(struct pinctrl_dev *pctldev,
>         return ret;
>  }
>
> +static u32 rzg2l_read_pin_config(struct rzg2l_pinctrl *pctrl, bool port_pin,
> +                                u32 offset, u8 bit, u32 mask)
> +{
> +       void __iomem *addr = pctrl->base + offset;
> +       unsigned long flags;
> +       u32 reg;
> +
> +       if (port_pin)
> +               addr += PORT_PIN_CFG_OFFSET;

I'm wondering if it would be better to handle this in the caller,
by passing an adjusted offset?
Same for rzg2l_rmw_pin_config().

> +
> +       /* handle _L/_H for 32-bit register read/write */
> +       if (bit >= 4) {
> +               bit -= 4;
> +               addr += 4;
> +       }
> +
> +       spin_lock_irqsave(&pctrl->lock, flags);
> +       reg = readl(addr) & (mask << (bit * 8));

The masking is not needed here, as it is done below.

> +       spin_unlock_irqrestore(&pctrl->lock, flags);

I still think you don't need that spinlock here, as reading a MMIO
register is an atomic operation.

(/me fixes drivers/pinctrl/renesas/pinctrl.c you referred to before)

> +       reg = (reg >> (bit * 8)) & mask;
> +
> +       return reg;

return (reg >> (bit * 8)) & mask;

> +}

> @@ -432,10 +480,11 @@ static int rzg2l_pinctrl_pinconf_get(struct pinctrl_dev *pctldev,
>         enum pin_config_param param = pinconf_to_config_param(*config);
>         const struct pinctrl_pin_desc *pin = &pctrl->desc.pins[_pin];
>         unsigned int *pin_data = pin->drv_data;
> +       bool port_pin = false;

Do you really need this?

>         unsigned int arg = 0;
>         unsigned long flags;
>         void __iomem *addr;
> -       u32 port = 0, reg;
> +       u32 port = 0;
>         u32 cfg = 0;
>         u8 bit = 0;
>
> @@ -452,17 +501,8 @@ static int rzg2l_pinctrl_pinconf_get(struct pinctrl_dev *pctldev,
>         case PIN_CONFIG_INPUT_ENABLE:
>                 if (!(cfg & PIN_CFG_IEN))
>                         return -EINVAL;
> -               spin_lock_irqsave(&pctrl->lock, flags);
> -               /* handle _L/_H for 32-bit register read/write */
> -               addr = pctrl->base + IEN(port);
> -               if (bit >= 4) {
> -                       bit -= 4;
> -                       addr += 4;
> -               }
>
> -               reg = readl(addr) & (IEN_MASK << (bit * 8));
> -               arg = (reg >> (bit * 8)) & 0x1;
> -               spin_unlock_irqrestore(&pctrl->lock, flags);
> +               arg = rzg2l_read_pin_config(pctrl, port_pin, IEN(port), bit, IEN_MASK);

port_pin is always false here, as PIN_CFG_IEN is only ever set for
dedicated pins.

Same comments for rzg2l_pinctrl_pinconf_set().

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds