linux-kernel - RE: [PATCH v2 07/12] i2c: riic: Define individual arrays to describe the register offsets

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Date: Fri, 28 Jun 2024 08:29:40 +0000
From: Biju Das <biju.das.jz@...renesas.com>
To: Biju Das <biju.das.jz@...renesas.com>, Claudiu.Beznea
	<claudiu.beznea@...on.dev>, Chris Brandt <Chris.Brandt@...esas.com>,
	"andi.shyti@...nel.org" <andi.shyti@...nel.org>, "robh@...nel.org"
	<robh@...nel.org>, "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>, "geert+renesas@...der.be"
	<geert+renesas@...der.be>, "magnus.damm@...il.com" <magnus.damm@...il.com>,
	"mturquette@...libre.com" <mturquette@...libre.com>, "sboyd@...nel.org"
	<sboyd@...nel.org>, "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
	"wsa+renesas@...g-engineering.com" <wsa+renesas@...g-engineering.com>
CC: "linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>, Claudiu Beznea
	<claudiu.beznea.uj@...renesas.com>
Subject: RE: [PATCH v2 07/12] i2c: riic: Define individual arrays to describe
 the register offsets

Hi Caludiu,

> -----Original Message-----
> From: Biju Das <biju.das.jz@...renesas.com>
> Sent: Friday, June 28, 2024 9:24 AM
> Subject: RE: [PATCH v2 07/12] i2c: riic: Define individual arrays to describe the register offsets
> 
> Hi Claudiu,
> 
> > -----Original Message-----
> > From: claudiu beznea <claudiu.beznea@...on.dev>
> > Sent: Friday, June 28, 2024 9:13 AM
> > Subject: Re: [PATCH v2 07/12] i2c: riic: Define individual arrays to
> > describe the register offsets
> >
> >
> >
> > On 28.06.2024 11:09, Biju Das wrote:
> > >
> > > Hi Claudiu,
> > >
> > >> -----Original Message-----
> > >> From: claudiu beznea <claudiu.beznea@...on.dev>
> > >> Sent: Friday, June 28, 2024 9:03 AM
> > >> Subject: Re: [PATCH v2 07/12] i2c: riic: Define individual arrays
> > >> to describe the register offsets
> > >>
> > >>
> > >>
> > >> On 28.06.2024 10:55, Biju Das wrote:
> > >>> Hi Claudiu,
> > >>>
> > >>>> -----Original Message-----
> > >>>> From: claudiu beznea <claudiu.beznea@...on.dev>
> > >>>> Sent: Friday, June 28, 2024 8:32 AM
> > >>>> Subject: Re: [PATCH v2 07/12] i2c: riic: Define individual arrays
> > >>>> to describe the register offsets
> > >>>>
> > >>>> Hi, Biju,
> > >>>>
> > >>>> On 28.06.2024 08:59, Biju Das wrote:
> > >>>>> Hi Claudiu,
> > >>>>>
> > >>>>>> -----Original Message-----
> > >>>>>> From: Claudiu <claudiu.beznea@...on.dev>
> > >>>>>> Sent: Tuesday, June 25, 2024 1:14 PM
> > >>>>>> Subject: [PATCH v2 07/12] i2c: riic: Define individual arrays
> > >>>>>> to describe the register offsets
> > >>>>>>
> > >>>>>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> > >>>>>>
> > >>>>>> Define individual arrays to describe the register offsets. In
> > >>>>>> this way we can describe different IP variants that share the
> > >>>>>> same register offsets but have differences in other characteristics.
> > >>>>>> Commit prepares for the addition
> > >>>> of fast mode plus.
> > >>>>>>
> > >>>>>> Signed-off-by: Claudiu Beznea
> > >>>>>> <claudiu.beznea.uj@...renesas.com>
> > >>>>>> ---
> > >>>>>>
> > >>>>>> Changes in v2:
> > >>>>>> - none
> > >>>>>>
> > >>>>>>  drivers/i2c/busses/i2c-riic.c | 58
> > >>>>>> +++++++++++++++++++----------------
> > >>>>>>  1 file changed, 31 insertions(+), 27 deletions(-)
> > >>>>>>
> > >>>>>> diff --git a/drivers/i2c/busses/i2c-riic.c
> > >>>>>> b/drivers/i2c/busses/i2c-riic.c index
> > >>>>>> 9fe007609076..8ffbead95492 100644
> > >>>>>> --- a/drivers/i2c/busses/i2c-riic.c
> > >>>>>> +++ b/drivers/i2c/busses/i2c-riic.c
> > >>>>>> @@ -91,7 +91,7 @@ enum riic_reg_list {  };
> > >>>>>>
> > >>>>>>  struct riic_of_data {
> > >>>>>> -	u8 regs[RIIC_REG_END];
> > >>>>>> +	const u8 *regs;
> > >>>>>
> > >>>>>
> > >>>>> Since you are touching this part, can we drop struct and Use u8*
> > >>>>> as device_data instead?
> > >>>>
> > >>>> Patch 09/12 "i2c: riic: Add support for fast mode plus" adds a
> > >>>> new member to struct
> > >> riic_of_data.
> > >>>> That new member is needed to differentiate b/w hardware versions
> > >>>> supporting fast mode plus based on compatible.
> > >>>
> > >>> Are we sure RZ/A does not support fast mode plus?
> > >>
> > >> From commit description of patch 09/12:
> > >>
> > >> Fast mode plus is available on most of the IP variants that RIIC
> > >> driver is working with. The exception is (according to HW manuals
> > >> of the SoCs where this IP is
> > available) the Renesas RZ/A1H.
> > >> For this, patch introduces the struct riic_of_data::fast_mode_plus.
> > >>
> > >> I checked the manuals of all the SoCs where this driver is used.
> > >>
> > >> I haven't checked the H/W manual?
> > >>
> > >> On the manual I've downloaded from Renesas web site the FMPE bit of
> > >> RIICnFER is not available on RZ/A1H.
> > >
> > > I just found RZ/A2M manual, it supports FMP and register layout looks similar to RZ/G2L.
> >
> > I introduced struct riic_of_data::fast_mode_plus because of RZ/A1H.
> 
> Maybe make the register layout as per SoC
> 
> RZ/A1 --> &riic_rz_a_info
> RZ/A2 and RZ/{G2L,G2LC,V2L,G2UL,FIVE} --> &riic_rz_g2_info RZ/G3S and RZ/V2H --> &riic_rz_v2h_info
> 
> Then except RZ/A1, set FMP.
> 
> Currently register layout of RZ/A2 is not matching with Hardware manual.

One more thing, From register layout, you can detect SOC has FMP capability or not
So you don’t need riic_of_data::fast_mode_plus.

Cheers,
Biju