From: Michael Walle <michael@walle.cc>
To: Lee Jones <lee.jones@linaro.org>
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, 02 Jul 2020 09:21:45 +0200 [thread overview]
Message-ID: <a8fc222a555f1b5bceb7405e94f7df0e@walle.cc> (raw)
In-Reply-To: <20200702071402.GP1179328@dell>
Am 2020-07-02 09:14, schrieb Lee Jones:
> On Tue, 30 Jun 2020, Michael Walle wrote:
>
>> Hi Lee,
>>
>> 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
>> >
>>
>> [..]
>>
>> > +static struct regmap *syscon_i2c_get_regmap(struct i2c_client *client,
>> > + struct regmap_config *regmap_config)
>> > +{
>> > + struct device *dev = &client->dev;
>> > + struct syscon *entry, *syscon = NULL;
>> > +
>> > + spin_lock(&syscon_i2c_list_slock);
>> > +
>> > + list_for_each_entry(entry, &syscon_i2c_list, list)
>> > + if (entry->dev == dev) {
>> > + syscon = entry;
>> > + break;
>> > + }
>> > +
>> > + spin_unlock(&syscon_i2c_list_slock);
>> > +
>> > + if (!syscon)
>> > + syscon = syscon_i2c_register(client, regmap_config);
>> > +
>> > + if (IS_ERR(syscon))
>> > + return ERR_CAST(syscon);
>> > +
>> > + return syscon->regmap;
>> > +}
>> > +
>> > +struct regmap *syscon_i2c_to_regmap_config(struct i2c_client *client,
>> > + struct regmap_config *regmap_config)
>> > +{
>> > + return syscon_i2c_get_regmap(client, regmap_config);
>> > +}
>> > +EXPORT_SYMBOL_GPL(syscon_i2c_to_regmap_config);
>> > +
>> > +struct regmap *syscon_i2c_to_regmap(struct i2c_client *client)
>> > +{
>> > + return syscon_i2c_get_regmap(client, &syscon_i2c_regmap_config);
>> > +}
>> > +EXPORT_SYMBOL_GPL(syscon_i2c_to_regmap);
>>
>> What do you think about
>>
>> struct regmap *syscon_i2c_to_regmap(struct device *dev)
>> {
>> struct i2c_client *client = i2c_verify_client(dev);
>>
>> if (!client)
>> return ERR_PTR(-EINVAL);
>>
>> return syscon_i2c_get_regmap(client, &syscon_i2c_regmap_config);
>> }
>>
>> Or even move it to syscon_i2c_get_regmap().
>>
>> 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.
>
> What is your use-case?
Still my sl28 mfd driver. There the sub devices just need a regmap.
> This is set-up for based I2C drivers to call
> into. 'client' is given to them as their .probe() arg.
Ok, I see. Then this doesn't fit.
-michael
>> 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.
>
> This is a helper for I2C clients. There aren't any OF helpers in here
> (yet). If you think they would be helpful we can add them. How do
> you see them being used?
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next prev parent reply other threads:[~2020-07-02 7:23 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
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 [this message]
2020-07-05 13:10 ` kernel test robot
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