Messages in this thread | | | Date | Wed, 01 Jul 2020 23:01:26 +0200 | From | Michael Walle <> | Subject | Re: [PATCH v4 1/1] mfd: Add I2C based System Configuaration (SYSCON) access |
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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 >> > > >> > >> > [..] >> > >> > > +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>; >> }; >> }; >> }; > > 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. 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(). 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..
-michael
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