From: Lee Jones <lee.jones@linaro.org>
To: Michael Walle <michael@walle.cc>
Cc: "Andy Shevchenko" <andy.shevchenko@gmail.com>,
"Ranjani Sridharan" <ranjani.sridharan@linux.intel.com>,
david.m.ertman@intel.com, shiraz.saleem@intel.com,
"Rob Herring" <robh+dt@kernel.org>,
"Mark Brown" <broonie@kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org,
linux-watchdog@vger.kernel.org,
"linux-arm Mailing List" <linux-arm-kernel@lists.infradead.org>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
"Jean Delvare" <jdelvare@suse.com>,
"Guenter Roeck" <linux@roeck-us.net>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Wim Van Sebroeck" <wim@linux-watchdog.org>,
"Shawn Guo" <shawnguo@kernel.org>, "Li Yang" <leoyang.li@nxp.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jason Cooper" <jason@lakedaemon.net>,
"Marc Zyngier" <maz@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller
Date: Tue, 9 Jun 2020 16:19:41 +0100 [thread overview]
Message-ID: <20200609151941.GM4106@dell> (raw)
In-Reply-To: <32287ac0488f7cbd5a7d1259c284e554@walle.cc>
On Tue, 09 Jun 2020, Michael Walle wrote:
> Am 2020-06-09 08:47, schrieb Lee Jones:
> > On Mon, 08 Jun 2020, Michael Walle wrote:
> >
> > > Am 2020-06-08 20:56, schrieb Lee Jones:
> > > > On Mon, 08 Jun 2020, Michael Walle wrote:
> > > >
> > > > > Am 2020-06-08 12:02, schrieb Andy Shevchenko:
> > > > > > +Cc: some Intel people WRT our internal discussion about similar
> > > > > > problem and solutions.
> > > > > >
> > > > > > On Mon, Jun 8, 2020 at 11:30 AM Lee Jones <lee.jones@linaro.org> wrote:
> > > > > > > On Sat, 06 Jun 2020, Michael Walle wrote:
> > > > > > > > Am 2020-06-06 13:46, schrieb Mark Brown:
> > > > > > > > > On Fri, Jun 05, 2020 at 10:07:36PM +0200, Michael Walle wrote:
> > > > > > > > > > Am 2020-06-05 12:50, schrieb Mark Brown:
> > > > > >
> > > > > > ...
> > > > > >
> > > > > > > Right. I'm suggesting a means to extrapolate complex shared and
> > > > > > > sometimes intertwined batches of register sets to be consumed by
> > > > > > > multiple (sub-)devices spanning different subsystems.
> > > > > > >
> > > > > > > Actually scrap that. The most common case I see is a single Regmap
> > > > > > > covering all child-devices.
> > > > > >
> > > > > > Yes, because often we need a synchronization across the entire address
> > > > > > space of the (parent) device in question.
> > > > > >
> > > > > > > It would be great if there was a way in
> > > > > > > which we could make an assumption that the entire register address
> > > > > > > space for a 'tagged' (MFD) device is to be shared (via Regmap) between
> > > > > > > each of the devices described by its child-nodes. Probably by picking
> > > > > > > up on the 'simple-mfd' compatible string in the first instance.
> > > > > > >
> > > > > > > Rob, is the above something you would contemplate?
> > > > > > >
> > > > > > > Michael, do your register addresses overlap i.e. are they intermingled
> > > > > > > with one another? Do multiple child devices need access to the same
> > > > > > > registers i.e. are they shared?
> > > > >
> > > > > No they don't overlap, expect for maybe the version register, which is
> > > > > just there once and not per function block.
> > > >
> > > > Then what's stopping you having each device Regmap their own space?
> > >
> > > Because its just one I2C device, AFAIK thats not possible, right?
> >
> > Not sure what (if any) the restrictions are.
>
> You can only have one device per I2C address. Therefore, I need one device
> which is enumerated by the I2C bus, which then enumerates its sub-devices.
> I thought this was one of the use cases for MFD. (Regardless of how a
> sub-device access its registers). So even in the "simple-regmap" case this
> would need to be an i2c device.
>
> E.g.
>
> &i2cbus {
> mfd-device@10 {
> compatible = "simple-regmap", "simple-mfd";
> reg = <10>;
> regmap,reg-bits = <8>;
> regmap,val-bits = <8>;
> sub-device@0 {
> compatible = "vendor,sub-device0";
> reg = <0>;
> };
> ...
> };
>
> Or if you just want the regmap:
>
> &soc {
> regmap: regmap@fff0000 {
> compatible = "simple-regmap";
> reg = <0xfff0000>;
> regmap,reg-bits = <16>;
> regmap,val-bits = <32>;
> };
>
> enet-which-needs-syscon-too@1000000 {
> vendor,ctrl-regmap = <®map>;
> };
> };
>
> Similar to the current syscon (which is MMIO only..).
We do not need a 'simple-regmap' solution for your use-case.
Since your device's registers are segregated, just split up the
register map and allocate each sub-device with it's own slice.
> > I can't think of any reasons why not, off the top of my head.
> >
> > Does Regmap only deal with shared accesses from multiple devices
> > accessing a single register map, or can it also handle multiple
> > devices communicating over a single I2C channel?
> >
> > One for Mark perhaps.
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2020-06-09 15:19 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 21:10 [PATCH v4 00/11] Add support for Kontron sl28cpld Michael Walle
2020-06-04 21:10 ` [PATCH v4 01/11] dt-bindings: mfd: Add bindings for sl28cpld Michael Walle
2020-06-09 16:28 ` Rob Herring
2020-06-04 21:10 ` [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller Michael Walle
2020-06-05 6:57 ` Lee Jones
2020-06-05 9:51 ` Michael Walle
2020-06-05 10:50 ` Mark Brown
2020-06-05 20:07 ` Michael Walle
2020-06-06 11:46 ` Mark Brown
2020-06-06 12:45 ` Michael Walle
2020-06-08 8:28 ` Lee Jones
2020-06-08 10:02 ` Andy Shevchenko
2020-06-08 15:41 ` Michael Walle
2020-06-08 18:56 ` Lee Jones
2020-06-08 21:09 ` Michael Walle
2020-06-09 6:47 ` Lee Jones
2020-06-09 14:38 ` Michael Walle
2020-06-09 14:42 ` Mark Brown
2020-06-09 15:01 ` Michael Walle
2020-06-09 17:15 ` Rob Herring
2020-06-09 17:29 ` Mark Brown
2020-06-09 18:41 ` Lee Jones
2020-06-09 15:19 ` Lee Jones [this message]
2020-06-09 15:30 ` Michael Walle
2020-06-09 19:45 ` Lee Jones
2020-06-10 7:10 ` Michael Walle
2020-06-10 7:19 ` Lee Jones
2020-06-10 7:49 ` Michael Walle
2020-06-10 7:56 ` Lee Jones
2020-06-10 9:27 ` Michael Walle
2020-06-10 18:30 ` Lee Jones
2020-06-10 17:16 ` Rob Herring
2020-06-10 18:02 ` Lee Jones
2020-06-08 18:20 ` Lee Jones
2020-06-09 16:54 ` Rob Herring
2020-06-09 18:52 ` Lee Jones
2020-06-05 8:01 ` Andy Shevchenko
2020-06-05 8:02 ` Andy Shevchenko
2020-06-05 10:09 ` Michael Walle
2020-06-05 10:48 ` Andy Shevchenko
2020-06-05 11:51 ` Michael Walle
2020-06-04 21:10 ` [PATCH v4 03/11] irqchip: add sl28cpld interrupt controller support Michael Walle
2020-06-05 1:26 ` kernel test robot
2020-06-05 8:07 ` Andy Shevchenko
2020-06-08 15:12 ` kernel test robot
2020-06-04 21:10 ` [PATCH v4 04/11] watchdog: add support for sl28cpld watchdog Michael Walle
2020-06-05 8:14 ` Andy Shevchenko
2020-06-05 10:24 ` Michael Walle
2020-06-05 10:50 ` Andy Shevchenko
2020-06-05 13:52 ` Guenter Roeck
2020-06-05 14:09 ` Andy Shevchenko
2020-06-05 15:05 ` Guenter Roeck
2020-06-05 16:04 ` Andy Shevchenko
2020-06-05 16:34 ` Guenter Roeck
2020-06-04 21:10 ` [PATCH v4 05/11] pwm: add support for sl28cpld PWM controller Michael Walle
2020-06-05 8:15 ` Andy Shevchenko
2020-06-05 8:49 ` Lee Jones
2020-06-05 9:33 ` Andy Shevchenko
2020-06-05 11:39 ` Michael Walle
2020-06-05 18:17 ` Michael Walle
2020-06-08 7:46 ` Lee Jones
2020-06-04 21:10 ` [PATCH v4 06/11] gpio: add support for the sl28cpld GPIO controller Michael Walle
2020-06-05 12:00 ` Andy Shevchenko
2020-06-05 12:42 ` Michael Walle
2020-06-05 13:15 ` Andy Shevchenko
2020-06-05 18:44 ` Michael Walle
2020-06-05 21:19 ` Andy Shevchenko
2020-06-04 21:10 ` [PATCH v4 07/11] hwmon: add support for the sl28cpld hardware monitoring controller Michael Walle
2020-06-05 12:06 ` Andy Shevchenko
2020-06-04 21:10 ` [PATCH v4 08/11] arm64: dts: freescale: sl28: enable sl28cpld Michael Walle
2020-06-04 21:10 ` [PATCH v4 09/11] arm64: dts: freescale: sl28: map GPIOs to input events Michael Walle
2020-06-04 21:10 ` [PATCH v4 10/11] arm64: dts: freescale: sl28: enable LED support Michael Walle
2020-06-04 21:10 ` [PATCH v4 11/11] arm64: dts: freescale: sl28: enable fan support Michael Walle
2020-06-05 6:13 ` [PATCH v4 00/11] Add support for Kontron sl28cpld Lee Jones
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