linux-kernel - Re: [PATCH v3 1/3] pinctrl: renesas: rzg2l: Include pinmap in RZG2L_GPIO_PORT

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Message-ID: <CAMuHMdXYEBg7MMJG7tqDib8eaKdvd4Fxo+ZR8K8Vq82DzjSaqg@mail.gmail.com>
Date: Thu, 4 Jan 2024 17:24:55 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc: Magnus Damm <magnus.damm@...il.com>, Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Linus Walleij <linus.walleij@...aro.org>, 
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	linux-gpio@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v3 1/3] pinctrl: renesas: rzg2l: Include pinmap in
 RZG2L_GPIO_PORT_PACK() macro

Hi Prabhakar,

On Thu, Jan 4, 2024 at 4:55 PM Lad, Prabhakar
<prabhakar.csengg@...il.com> wrote:
> On Tue, Jan 2, 2024 at 10:18 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Thu, Dec 21, 2023 at 10:04 PM Lad, Prabhakar
> > <prabhakar.csengg@...il.com> wrote:
> > > On Wed, Dec 6, 2023 at 1:13 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > > > On Fri, Dec 1, 2023 at 2:16 PM Prabhakar <prabhakar.csengg@...il.com> wrote:
> > > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > > >
> > > > > Currently we assume all the port pins are sequential ie always PX_0 to
> > > > > PX_n (n=1..7) exist, but on RZ/Five SoC we have additional pins P19_1 to
> > > > > P28_5 which have holes in them, for example only one pin on port19 is
> > > > > available and that is P19_1 and not P19_0. So to handle such cases
> > > > > include pinmap for each port which would indicate the pin availability
> > > > > on each port. As the pincount can be calculated based on pinmap drop this
> > > > > from RZG2L_GPIO_PORT_PACK() macro and update RZG2L_GPIO_PORT_GET_PINCNT()
> > > > > macro.
> > > > >
> > > > > Previously we had a max of 7 pins on each port but on RZ/Five Port-20
> > > > > has 8 pins, so move the single pin configuration to BIT(63).
> > > > >
> > > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > >
> > > > Thanks for your patch!
> > > >
> > > > > --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > > > > +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > > > > @@ -80,15 +80,17 @@
> > > > >   * n indicates number of pins in the port, a is the register index
> > > > >   * and f is pin configuration capabilities supported.
> > > > >   */
> > > > > -#define RZG2L_GPIO_PORT_PACK(n, a, f)  (((n) << 28) | ((a) << 20) | (f))
> > > > > -#define RZG2L_GPIO_PORT_GET_PINCNT(x)  (((x) & GENMASK(30, 28)) >> 28)
> > > > > +#define RZG2L_GPIO_PORT_PACK(n, a, f)  (((n) > 0 ? ((u64)(GENMASK_ULL(((n) - 1 + 28), 28))) : 0) | \
> > > >
> > > > The mask creation can be simplified to
> > > >
> > > >     ((1ULL << (n)) - 1) << 28
> > > >
> > > OK.
> > >
> > > > but see below...
> > > >
> > > > > +                                        ((a) << 20) | (f))
> > > > > +#define RZG2L_GPIO_PORT_GET_PINMAP(x)  (((x) & GENMASK_ULL(35, 28)) >> 28)
> > > > > +#define RZG2L_GPIO_PORT_GET_PINCNT(x)  (hweight8(RZG2L_GPIO_PORT_GET_PINMAP((x))))
> > > >
> > > > I think we've reached the point where it would be easier for the
> > > > casual reviewer to #define PIN_CFG_*_MASK for all fields, and use
> > > > FIELD_{PREP,GET}() to pack resp. extract values.  That would also
> > > > make it more obvious which bits are in use, and how many bits are
> > > > still available for future use.

> To clarify, you mean to define PIN_CFG_*_MASK for all
> PIN_CFG_IOLH_A..PIN_CFG_OEN macros? I ask because we dont extract the
> respective CFG flags in the code.

The PIN_CFG_IOLH_A..PIN_CFG_OEN macros are single-bit definitions.
I mean to #define PIN_CFG_*_MASK macros for all multi-bit fields, currently
accessed using open-coded GENMASK().

You already tried:

    #define RZG2L_GPIO_PORT_PIN_CNT_MASK    GENMASK(31, 28)
    #define RZG2L_GPIO_PORT_PIN_REG_MASK    GENMASK(27, 20)
    #define RZG2L_GPIO_PORT_PIN_CFG_MASK    GENMASK(19, 0)

As they actually share the PIN_CFG_* bit space, I'd call them:

    #define PIN_CFG_PIN_CNT_MASK    GENMASK(31, 28)
    #define PIN_CFG_PIN_REG_MASK    GENMASK(27, 20)
    #define PIN_CFG_MASK    GENMASK(19, 0)

Also, you already have:

    #define MUX_PIN_ID_MASK         GENMASK(15, 0)
    #define MUX_FUNC_MASK           GENMASK(31, 16)
    #define MUX_FUNC_OFFS           16

But all of

    #define MUX_FUNC(pinconf)       (((pinconf) & MUX_FUNC_MASK) >>
MUX_FUNC_OFFS)

    pins[i] = value & MUX_PIN_ID_MASK;

can use FIELD_GET(), removing the need for MUX_FUNC_OFFS.

Also:

    u8 pincount = RZG2L_GPIO_PORT_GET_PINCNT(cfg);

can become

    u8 pincount = FIELD_GET(PIN_CFG_PIN_CNT_MASK, cfg);

Same for all the other macros using GENMASK().

I hope this makes it more clear what I had in mind?
Thanks!

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