From: Lee Jones <lee.jones@linaro.org>
To: Michael Walle <michael@walle.cc>
Cc: devicetree@vger.kernel.org, arnd@arndb.de,
gregkh@linuxfoundation.org, linus.walleij@linaro.org,
linux-kernel@vger.kernel.org, robh+dt@kernel.org,
bgolaszewski@baylibre.com, broonie@kernel.org,
andriy.shevchenko@linux.intel.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 1/1] mfd: Add I2C based System Configuaration (SYSCON) access
Date: Thu, 2 Jul 2020 07:54:12 +0100 [thread overview]
Message-ID: <20200702065412.GO1179328@dell> (raw)
In-Reply-To: <5d1d41504172d86d395b0135923f6f02@walle.cc>
On Wed, 01 Jul 2020, Michael Walle wrote:
> Am 2020-07-01 09:04, schrieb Lee Jones:
> > On Wed, 01 Jul 2020, Michael Walle wrote:
> >
> > > Hi Lee,
> > >
> > > Am 2020-06-30 11:16, schrieb Michael Walle:
> > > > I'm just trying to use this for my sl28 driver. Some remarks, see below.
> > > >
> > > > Am 2020-06-22 09:51, schrieb Lee Jones:
> > > > > The existing SYSCON implementation only supports MMIO (memory mapped)
> > > > > accesses, facilitated by Regmap. This extends support for registers
> > > > > held behind I2C busses.
> > > > >
> > > > > Signed-off-by: Lee Jones <lee.jones@linaro.org>
> > > > > ---
> > > > > Changelog:
> > > > >
> > > > > v3 => v4
> > > > > - Add ability to provide a non-default Regmap configuration
> > > > >
> > > > > v2 => v3
> > > > > - Change 'is CONFIG' present check to include loadable modules
> > > > > - s/#ifdef CONFIG_MFD_SYSCON_I2C/#if
> > > > > IS_ENABLED(CONFIG_MFD_SYSCON_I2C)/
> > > > >
> > > > > v1 => v2
> > > > > - Remove legacy references to OF
> > > > > - Allow building as a module (fixes h8300 0-day issue)
> > > > >
> > > > > drivers/mfd/Kconfig | 7 +++
> > > > > drivers/mfd/Makefile | 1 +
> > > > > drivers/mfd/syscon-i2c.c | 104
> > > > > +++++++++++++++++++++++++++++++++
> > > > > include/linux/mfd/syscon-i2c.h | 36 ++++++++++++
> > > > > 4 files changed, 148 insertions(+)
> > > > > create mode 100644 drivers/mfd/syscon-i2c.c
> > > > > create mode 100644 include/linux/mfd/syscon-i2c.h
[...]
> > > > This way, (a) a driver doesn't have to use "#include <linux/i2c.h>" just
> > > > to call to_i2c_client() (or i2c_verify_client()) and (b) you won't do it
> > > > all over again in all sub drivers.
> > > >
> > > > So you could just do a
> > > > regmap = syscon_i2c_to_regmap(pdev->dev.parent);
> > > >
> > > > I've also noticed that the mmio syscon uses device_node as parameter.
> > > > What
> > > > was the reason to divert from that? Just curious.
> > >
> > > How is this supposed to be used?
> > >
> > > I had something like the following in mind:
> > >
> > > &i2c {
> > > cpld@4a {
> > > compatible = "simple-mfd";
> > > reg = <0x4a>;
> > >
> > > gpio@4 {
> > > compatible = "vendor,gpio";
> > > reg = <0x4>;
> > > };
> > > };
> > > };
> >
> > Yes, that was the idea.
> >
> > > But I think the childen are not enumerated if its an I2C device. And
> > > the actual i2c driver is also missing.
> >
> > What do you mean? Can you elaborate?
>
> There is no i2c_driver instance who would create the regmap.
The regmap is created by the first caller of:
syscon_i2c_to_regmap{_config}()
> If I'm
> reading the I2C code correctly, it won't probe any i2c device of a
> bus if there is no i2c_driver with an associated .probe() or
> .probe_new().
Why wouldn't the children be registered using i2c_driver?
> And even if it is probed, its subnodes won't be
> enumerated; the "simple-mfd" code only works for MMIO busses, right?
> Or I'm getting something really wrong here..
Then how are these I2C based devices able to call of_platform_populate()?
drivers/mfd/gateworks-gsc.c
drivers/mfd/lochnagar-i2c.c
drivers/mfd/palmas.c
drivers/mfd/smsc-ece1099.c
drivers/mfd/stpmic1.c
drivers/mfd/twl-core.c
Might require some more research into where your use-case is breaking
down.
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-07-02 6:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200622075145.1464020-1-lee.jones@linaro.org>
2020-06-30 9:16 ` [PATCH v4 1/1] mfd: Add I2C based System Configuaration (SYSCON) access Michael Walle
2020-06-30 22:32 ` Michael Walle
2020-07-01 7:04 ` Lee Jones
2020-07-01 21:01 ` Michael Walle
2020-07-02 6:54 ` Lee Jones [this message]
2020-07-02 7:02 ` Michael Walle
2020-07-02 8:18 ` Lee Jones
2020-07-02 9:12 ` Michael Walle
2020-07-02 7:14 ` Lee Jones
2020-07-02 7:21 ` Michael Walle
2020-07-05 13:10 ` kernel test robot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200702065412.GO1179328@dell \
--to=lee.jones@linaro.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=arnd@arndb.de \
--cc=bgolaszewski@baylibre.com \
--cc=broonie@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=linus.walleij@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=michael@walle.cc \
--cc=robh+dt@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).