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

From: Guenter Roeck
Date: Wed Sep 24 2014 - 17:22:22 EST

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On Wed, Sep 24, 2014 at 04:06:11PM -0500, atull wrote:
> 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.
>
Even better ;)

> >
> > > +
> > > +/*
> > > * 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.
>
Don't spend too much time on it. I'll accept it either way.

> >
> > > /* 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?
>
Ok.

> >
> > > + 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.
>
That is true.

> >
> > > +};
> > > +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.
>
Guess we can do that if/when it is needed. So far there is only one flag bit,
and that isn't widely needed. I am not even sure if it is needed anymore in the
first place - I'll have to go back to my notes to find out which chips actually
need it. We may have other means today to accomplish the same, via an explicit
chip driver.

> What do you think?
>
I'd keep it simple for now, and only parse reglator data.

Guenter
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Next message: Andrew Morton: "Re: [PATCH] lib: string.c: Added a funktion function strzcpy"
Previous message: Wolfram Sang: "Re: [PATCH] [REGRESSION] i2c-acpi: Fix NULL Pointer dereference"
In reply to: atull: "Re: [PATCH v3 2/3] pmbus: add regulator support"
Next in thread: atull: "[PATCH v3 1/3] pmbus: core: add helpers for byte write and read modify write"
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