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@xxxxxxxxxx>
> > ---
> > 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? This is set-up for based I2C drivers to call
into. 'client' is given to them as their .probe() arg.
> 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?
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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