Re: [PATCH v3 2/3] pmbus: add regulator support

From: atull
Date: Wed Sep 24 2014 - 17:12:23 EST

On Wed, 24 Sep 2014, Guenter Roeck wrote:

> On Wed, Sep 24, 2014 at 12:57:55PM -0500, atull@xxxxxxxxxxxxxxxxxxxxx wrote:
> > From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> >
> > Add support for simple on/off control of each channel.
> >
> > To add regulator support, the pmbus part driver needs to add
> > regulator_desc information, of_regulator_match information,
> > and number of regulators to its pmbus_driver_info struct.
> >
> > regulator_desc can be declared using default macro for a
> > regulator (PMBUS_REGULATOR) that is in pmbus.h
> >
> > The regulator_init_data can be intialized from either
> > platform data or the device tree.
> >
> > Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> >
>
> Hi Alan,
>
> Overall looks pretty good. Couple of comments inline.
>

Hi Guenter,

> > v2: Remove '#include <linux/regulator/machine.h>'
> > Only one regulator per pmbus device
> > Get regulator_init_data from pdata or device tree
> >
> > v3: Support multiple regulators for each chip
> > Move most code to pmbus_core.c
> > fixed values for on/off
> > ---
> > drivers/hwmon/pmbus/pmbus.h | 27 ++++++++
> > drivers/hwmon/pmbus/pmbus_core.c | 133 ++++++++++++++++++++++++++++++++++++++
> > include/linux/i2c/pmbus.h | 4 ++
> > 3 files changed, 164 insertions(+)
> >
> > diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> > index fa9beb3..74aa382 100644
> > --- a/drivers/hwmon/pmbus/pmbus.h
> > +++ b/drivers/hwmon/pmbus/pmbus.h
> > @@ -19,6 +19,9 @@
> > * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > */
> >
> > +#include <linux/regulator/driver.h>
> > +#include <linux/regulator/of_regulator.h>
> > +
> > #ifndef PMBUS_H
> > #define PMBUS_H
> >
> > @@ -186,6 +189,12 @@
> > #define PMBUS_VIRT_STATUS_VMON (PMBUS_VIRT_BASE + 35)
> >
> > /*
> > + * OPERATION
> > + */
> > +#define PB_OPERATION_CONTROL_ON (1<<7)
> > +#define PB_OPERATION_CONTROL_SEQ_OFF (1<<6)
>
> Can those defines be more consistent ? Does it really need SEQ_OFF or can it
> just be OFF ?

PB_OPERATION_CONTROL_SEQ_OFF is not used, so I will eliminate it.

>
> > +
> > +/*
> > * CAPABILITY
> > */
> > #define PB_CAPABILITY_SMBALERT (1<<4)
> > @@ -365,8 +374,26 @@ struct pmbus_driver_info {
> > */
> > int (*identify)(struct i2c_client *client,
> > struct pmbus_driver_info *info);
> > +
> > + /* Regulator functionality, if supported by this chip driver. */
> > + int num_regulators;
> > + const struct regulator_desc *reg_desc;
> > + struct of_regulator_match *reg_matches;
> > };
> >
> > +/* Regulator ops */
> > +
> > +extern struct regulator_ops pmbus_regulator_regulator_ops;
> > +
> How about just pmbus_regulator_ops ? I don't see a double regulator_
> variable name anywhere else in the code, and I don't really see the
> benefit of it.

That was a mistake. No need for double regulators here.

>
> > +/* Macro for filling in array of struct regulator_desc */
> > +#define PMBUS_REGULATOR(_name, _id) \
> > + [_id] = { \
> > + .name = (_name # _id), \
> > + .id = (_id), \
> > + .ops = &pmbus_regulator_regulator_ops, \
> > + .owner = THIS_MODULE, \
> > + }
> > +
>
> Any idea how/if we can get rid of the resulting checkpatch error ?

I banged my head on that for a while. I'll try some more.

>
> > /* Function declarations */
> >
> > void pmbus_clear_cache(struct i2c_client *client);
> > diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> > index d6c3701..9ab8bd4 100644
> > --- a/drivers/hwmon/pmbus/pmbus_core.c
> > +++ b/drivers/hwmon/pmbus/pmbus_core.c
> > @@ -29,6 +29,9 @@
> > #include <linux/hwmon-sysfs.h>
> > #include <linux/jiffies.h>
> > #include <linux/i2c/pmbus.h>
> > +#include <linux/regulator/of_regulator.h>
> > +#include <linux/regulator/driver.h>
> > +#include <linux/regulator/machine.h>
> > #include "pmbus.h"
> >
> > /*
> > @@ -1758,6 +1761,125 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
> > return 0;
> > }
> >
> > +#if IS_ENABLED(CONFIG_REGULATOR)
> > +static int pmbus_regulator_is_enabled(struct regulator_dev *rdev)
> > +{
> > + struct device *dev = rdev_get_dev(rdev);
> > + struct i2c_client *client = to_i2c_client(dev->parent);
> > + u8 page = rdev_get_id(rdev);
> > + int ret;
> > +
> > + ret = pmbus_read_byte_data(client, page, PMBUS_OPERATION);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return !!(ret & PB_OPERATION_CONTROL_ON);
> > +}
> > +
> > +static int _pmbus_regulator_enable(struct regulator_dev *rdev, bool enable)
> > +{
>
> Can you find a better name for this function ? After all,
> it doesn't just enable the regulator, it also disables it.

_pmbus_regulator_on_off?

>
> > + struct device *dev = rdev_get_dev(rdev);
> > + struct i2c_client *client = to_i2c_client(dev->parent);
> > + u8 val, page = rdev_get_id(rdev);
> > +
> > + if (enable)
> > + val = PB_OPERATION_CONTROL_ON;
> > + else
> > + val = 0;
> > +
> > + return pmbus_update_byte_data(client, page, PMBUS_OPERATION,
> > + PB_OPERATION_CONTROL_ON, val);
>
> enable ? PB_OPERATION_CONTROL_ON : 0
>
> would be much simpler here.

OK

>
> > +}
> > +
> > +static int pmbus_regulator_enable(struct regulator_dev *rdev)
> > +{
> > + return _pmbus_regulator_enable(rdev, 1);
> > +}
> > +
> > +static int pmbus_regulator_disable(struct regulator_dev *rdev)
> > +{
> > + return _pmbus_regulator_enable(rdev, 0);
> > +}
> > +
> > +struct regulator_ops pmbus_regulator_regulator_ops = {
> > + .enable = pmbus_regulator_enable,
> > + .disable = pmbus_regulator_disable,
> > + .is_enabled = pmbus_regulator_is_enabled,
>
> No get_voltage support ?
>
> [ Guess it isn't mandatory. We can add it later to get this going. ]

Yep, no voltage support for now. But it will be straightforward for
someone to insert here and probably won't require rewriting any of
this.

>
> > +};
> > +EXPORT_SYMBOL_GPL(pmbus_regulator_regulator_ops);
> > +
> > +#if IS_ENABLED(CONFIG_OF)
> > +static int pmbus_regulator_parse_dt(struct device *dev,
> > + const struct pmbus_driver_info *info)
> > +{
> > + struct device_node *np_regulators;
> > + int ret;
> > +
> > + if (!info->num_regulators)
> > + return 0;
> > +
> > + if (!info->reg_matches || !info->reg_desc)
> > + return -EINVAL;
> > +
> > + np_regulators = of_get_child_by_name(dev->of_node, "regulators");
> > + if (!np_regulators)
> > + return 0;
> > +
> > + ret = of_regulator_match(dev, np_regulators, info->reg_matches,
> > + info->num_regulators);
> > + of_node_put(np_regulators);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return 0;
> > +}
> > +#else
> > +static int pmbus_regulator_parse_dt(struct device *dev,
> > + const struct pmbus_driver_info *info)
> > +{
> > + return 0;
> > +}
> > +#endif
> > +
> > +static int pmbus_regulator_register(struct pmbus_data *data)
> > +{
> > + struct device *dev = data->dev;
> > + const struct pmbus_driver_info *info = data->info;
> > + const struct pmbus_platform_data *pdata = dev_get_platdata(dev);
> > + struct regulator_dev *rdev;
> > + int i;
> > +
> > + for (i = 0; i < info->num_regulators; i++) {
> > + struct regulator_config config = { };
> > +
> > + config.dev = dev;
> > + config.driver_data = data;
> > +
> > + if (pdata && pdata->reg_init_data) {
> > + config.init_data = &pdata->reg_init_data[i];
> > + } else {
> > + config.init_data = info->reg_matches[i].init_data;
> > + config.of_node = info->reg_matches[i].of_node;
> > + }
> > +
> > + rdev = devm_regulator_register(dev, &info->reg_desc[i],
> > + &config);
> > + if (IS_ERR(rdev)) {
> > + dev_err(dev, "Failed to register %s regulator\n",
> > + info->reg_desc[i].name);
> > + return PTR_ERR(rdev);
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +#else
> > +static int pmbus_regulator_register(struct pmbus_data *data)
> > +{
> > + return 0;
> > +}
> > +#endif
> > +
> > int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
> > struct pmbus_driver_info *info)
> > {
> > @@ -1769,6 +1891,10 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
> > if (!info)
> > return -ENODEV;
> >
> > + ret = pmbus_regulator_parse_dt(dev, info);
> > + if (ret)
> > + return ret;
> > +
>
> You have the conditions wrong above.
>
> If CONFIG_REGULATOR is not enabled, this will fail to build,
> since pmbus_regulator_parse_dt is not declared at all in this case.
>
> I can understand that you want to parse the dt early, but it would be
> simpler to just parse it from pmbus_regulator_register(). It is only
> relevant if regulators are configured anyway, and we don't really need
> to optimize the code for the error case.

I was thinking of adding the flags to the device tree parsing code. That
is the only other thing this driver is taking from the platform data. If I
do that, this driver will be completely done for device tree. I could do
that by adding a 'pmbus-skip-status-check' device tree property. That
would be a small change, but I would still need to parse the dt early.
Otherwise I can redo the code as you are recommending above.

What do you think?

Thanks for the review,

Alan

>
> > if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE
> > | I2C_FUNC_SMBUS_BYTE_DATA
> > | I2C_FUNC_SMBUS_WORD_DATA))
> > @@ -1812,8 +1938,15 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
> > dev_err(dev, "Failed to register hwmon device\n");
> > goto out_kfree;
> > }
> > +
> > + ret = pmbus_regulator_register(data);
> > + if (ret)
> > + goto out_unregister;
> > +
> > return 0;
> >
> > +out_unregister:
> > + hwmon_device_unregister(data->hwmon_dev);
> > out_kfree:
> > kfree(data->group.attrs);
> > return ret;
> > diff --git a/include/linux/i2c/pmbus.h b/include/linux/i2c/pmbus.h
> > index 69280db..ee3c2ab 100644
> > --- a/include/linux/i2c/pmbus.h
> > +++ b/include/linux/i2c/pmbus.h
> > @@ -40,6 +40,10 @@
> >
> > struct pmbus_platform_data {
> > u32 flags; /* Device specific flags */
> > +
> > + /* regulator support */
> > + int num_regulators;
> > + struct regulator_init_data *reg_init_data;
> > };
> >
> > #endif /* _PMBUS_H_ */
> > --
> > 1.7.9.5
> >
>
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