Linux-ARM-Kernel Archive on lore.kernel.org
 help / color / Atom feed
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: Wed, 01 Jul 2020 00:32:13 +0200
Message-ID: <f505c52d565ba7dbf05eef895782c410@walle.cc> (raw)
In-Reply-To: <e436fd60bf0ebb6d72a76034d0fc35de@walle.cc>

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
>> 
> 
> [..]
> 
>> +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.
> 
> 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>;
     };
   };
};

But I think the childen are not enumerated if its an I2C device. And
the actual i2c driver is also missing.

-michael

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply index

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 ` Michael Walle
2020-06-30 22:32   ` Michael Walle [this message]
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
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=f505c52d565ba7dbf05eef895782c410@walle.cc \
    --to=michael@walle.cc \
    --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=lee.jones@linaro.org \
    --cc=linus.walleij@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --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

Linux-ARM-Kernel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/0 linux-arm-kernel/git/0.git
	git clone --mirror https://lore.kernel.org/linux-arm-kernel/1 linux-arm-kernel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-arm-kernel linux-arm-kernel/ https://lore.kernel.org/linux-arm-kernel \
		linux-arm-kernel@lists.infradead.org
	public-inbox-index linux-arm-kernel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-arm-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git