RE: [PATCH 4/5] i2c: riic: Pass register offsets and chip details as OF data

[Biju Das]

> -----Original Message-----
> From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> Sent: Friday, March 8, 2024 6:04 PM
> To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>; Chris Brandt <Chris.Brandt@xxxxxxxxxxx>; Andi Shyti
> <andi.shyti@xxxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; Magnus Damm
> <magnus.damm@xxxxxxxxx>; Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>; linux-renesas-
> soc@xxxxxxxxxxxxxxx; linux-i2c@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>; Prabhakar Mahadev Lad
> <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH 4/5] i2c: riic: Pass register offsets and chip details as OF data
> 
> Hi Biju,
> 
> On Fri, Mar 8, 2024 at 5:36 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> >
> > Hi Prabhakar,
> >
> > Thanks for the patch.
> >
> > > -----Original Message-----
> > > From: Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > Sent: Friday, March 8, 2024 5:27 PM
> > > Subject: [PATCH 4/5] i2c: riic: Pass register offsets and chip
> > > details as OF data
> > >
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > >
> > > With an increasing number of SoCs reusing this driver, each with
> > > slight variations in the RIIC IP, it becomes necessary to support
> > > passing these details as OF data. This approach simplifies the extension of the driver for other
> SoCs.
> > >
> > > This patch lays the groundwork for adding support for the Renesas RZ/V2H SoC.
> > >
> > > Signed-off-by: Lad Prabhakar
> > > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > Reviewed-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
> > > ---
> > >  drivers/i2c/busses/i2c-riic.c | 59
> > > ++++++++++++++++++++++++++---------
> > >  1 file changed, 44 insertions(+), 15 deletions(-)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-riic.c
> > > b/drivers/i2c/busses/i2c-riic.c index
> > > 49a12f1ecdf9..3398d639b754 100644
> > > --- a/drivers/i2c/busses/i2c-riic.c
> > > +++ b/drivers/i2c/busses/i2c-riic.c
> > > @@ -46,18 +46,6 @@
> > >  #include <linux/pm_runtime.h>
> > >  #include <linux/reset.h>
> > >
> > > -#define RIIC_ICCR1   0x00
> > > -#define RIIC_ICCR2   0x04
> > > -#define RIIC_ICMR1   0x08
> > > -#define RIIC_ICMR3   0x10
> > > -#define RIIC_ICSER   0x18
> > > -#define RIIC_ICIER   0x1c
> > > -#define RIIC_ICSR2   0x24
> > > -#define RIIC_ICBRL   0x34
> > > -#define RIIC_ICBRH   0x38
> > > -#define RIIC_ICDRT   0x3c
> > > -#define RIIC_ICDRR   0x40
> > > -
> > >  #define ICCR1_ICE    0x80
> > >  #define ICCR1_IICRST 0x40
> > >  #define ICCR1_SOWP   0x10
> > > @@ -87,6 +75,13 @@
> > >
> > >  #define RIIC_INIT_MSG        -1
> > >
> > > +#define RIIC_RZ_A_TYPE       0
> >
> > > +
> > > +struct riic_of_data {
> > > +     u8 family;
> >
> > Do you need family as compatible have this information?
> >
> Yes this is added to future proof it, as the RZ/V2H SoC has some bit differences in the slave address
> register as compared to RZ/A and RZ/G2L. Comparing the family outside probe is not always preferred
> hence this is added as part of OF data.

Ok. Got it.
But the family variable is unused and is wasting memory.
Simple reg layout is enough for device data??

Cheers,
Biju

> 
> Cheers,
> Prabhakar
> 
> > > +     u8 regs[];
> > > +};
> > > +
> > >  struct riic_dev {
> > >       void __iomem *base;
> > >       u8 *buf;
> > > @@ -94,6 +89,7 @@ struct riic_dev {
> > >       int bytes_left;
> > >       int err;
> > >       int is_last;
> > > +     const struct riic_of_data *info;
> > >       struct completion msg_done;
> > >       struct i2c_adapter adapter;
> > >       struct clk *clk;
> > > @@ -105,14 +101,28 @@ struct riic_irq_desc {
> > >       char *name;
> > >  };
> > >
> > > +enum riic_reg_list {
> > > +     RIIC_ICCR1 = 0,
> > > +     RIIC_ICCR2,
> > > +     RIIC_ICMR1,
> > > +     RIIC_ICMR3,
> > > +     RIIC_ICSER,
> > > +     RIIC_ICIER,
> > > +     RIIC_ICSR2,
> > > +     RIIC_ICBRL,
> > > +     RIIC_ICBRH,
> > > +     RIIC_ICDRT,
> > > +     RIIC_ICDRR,
> > > +};
> > > +
> > >  static inline void riic_writeb_reg(u8 val, struct riic_dev *riic, u8 offset)  {
> > > -     writeb(val, riic->base + offset);
> > > +     writeb(val, riic->base + riic->info->regs[offset]);
> > >  }
> > >
> > >  static inline u8 riic_readb_reg(struct riic_dev *riic, u8 offset)  {
> > > -     return readb(riic->base + offset);
> > > +     return readb(riic->base + riic->info->regs[offset]);
> > >  }
> > >
> > >  static inline void riic_clear_set_bit(struct riic_dev *riic, u8
> > > clear, u8 set, u8 reg) @@ -453,6
> > > +463,8 @@ static int riic_i2c_probe(struct platform_device *pdev)
> > >               }
> > >       }
> > >
> > > +     riic->info = of_device_get_match_data(&pdev->dev);
> > > +
> > >       adap = &riic->adapter;
> > >       i2c_set_adapdata(adap, riic);
> > >       strscpy(adap->name, "Renesas RIIC adapter",
> > > sizeof(adap->name)); @@ -497,8 +509,25 @@ static void riic_i2c_remove(struct platform_device *pdev)
> > >       pm_runtime_disable(&pdev->dev);  }
> > >
> > > +static const struct riic_of_data riic_rz_a_info = {
> > > +     .family = RIIC_RZ_A_TYPE,
> > > +     .regs = {
> > > +             [RIIC_ICCR1] = 0x00,
> > > +             [RIIC_ICCR2] = 0x04,
> > > +             [RIIC_ICMR1] = 0x08,
> > > +             [RIIC_ICMR3] = 0x10,
> > > +             [RIIC_ICSER] = 0x18,
> > > +             [RIIC_ICIER] = 0x1c,
> > > +             [RIIC_ICSR2] = 0x24,
> > > +             [RIIC_ICBRL] = 0x34,
> > > +             [RIIC_ICBRH] = 0x38,
> > > +             [RIIC_ICDRT] = 0x3c,
> > > +             [RIIC_ICDRR] = 0x40,
> > > +     },
> > > +};
> > > +
> > >  static const struct of_device_id riic_i2c_dt_ids[] = {
> > > -     { .compatible = "renesas,riic-rz", },
> > > +     { .compatible = "renesas,riic-rz", .data = &riic_rz_a_info },
> > >       { /* Sentinel */ },
> > >  };
> > >
> > > --
> > > 2.34.1
> > >
> >