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SubjectRe: [PATCH 3/3] hwmon: (lm75) Add regulator support
Date
On Thu, 2020-09-17 at 22:33 -0700, Guenter Roeck wrote:
> On 9/17/20 3:18 AM, Alban Bedel wrote:
> > Add regulator support for boards where the sensor first need to be
> > powered up before it can be used.
> >
> > Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
> > ---
> > drivers/hwmon/lm75.c | 31 +++++++++++++++++++++++++++++--
> > 1 file changed, 29 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
> > index ba0be48aeadd..b673f8d2ef20 100644
> > --- a/drivers/hwmon/lm75.c
> > +++ b/drivers/hwmon/lm75.c
> > @@ -17,6 +17,7 @@
> > #include <linux/of.h>
> > #include <linux/regmap.h>
> > #include <linux/util_macros.h>
> > +#include <linux/regulator/consumer.h>
> > #include "lm75.h"
> >
> > /*
> > @@ -101,6 +102,7 @@ static const unsigned short normal_i2c[] = {
> > 0x48, 0x49, 0x4a, 0x4b, 0x4c,
> > struct lm75_data {
> > struct i2c_client *client;
> > struct regmap *regmap;
> > + struct regulator *vs;
> > u8 orig_conf;
> > u8 current_conf;
> > u8 resolution; /* In bits, 9 to 16 */
> > @@ -540,6 +542,8 @@ static void lm75_remove(void *data)
> > struct i2c_client *client = lm75->client;
> >
> > i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
> > + if (lm75->vs)
> > + regulator_disable(lm75->vs);
> > }
> >
> > static int
> > @@ -567,6 +571,14 @@ lm75_probe(struct i2c_client *client, const
> > struct i2c_device_id *id)
> > data->client = client;
> > data->kind = kind;
> >
> > + data->vs = devm_regulator_get_optional(dev, "vs");
>
> Looking into the regulator API, it may be better if you use
> devm_regulator_get().
> AFAICS it returns a dummy regulator if there is none, and NULL if the
> regulator subsystem is disabled. So
> data->vs = devm_regulator_get(dev, "vs");
> if (IS_ERR(data->vs))
> return PTR_ERR(data->vs);
> should work and would be less messy.

Ok, I'll change that in the next version.

> > + if (IS_ERR(data->vs)) {
> > + if (PTR_ERR(data->vs) == -ENODEV)
> > + data->vs = NULL;
> > + else
> > + return PTR_ERR(data->vs);
> > + }
> > +
> > data->regmap = devm_regmap_init_i2c(client,
> > &lm75_regmap_config);
> > if (IS_ERR(data->regmap))
> > return PTR_ERR(data->regmap);
> > @@ -581,11 +593,21 @@ lm75_probe(struct i2c_client *client, const
> > struct i2c_device_id *id)
> > data->sample_time = data->params->default_sample_time;
> > data->resolution = data->params->default_resolution;
> >
> > + /* Enable the power */
> > + if (data->vs) {
> > + err = regulator_enable(data->vs);
> > + if (err) {
> > + dev_err(dev, "failed to enable regulator:
> > %d\n", err);
> > + return err;
> > + }
> > + }
> > +
>
> How about device removal ? Don't you have to call regulator_disable()
> there as well ? If so, it might be best to use
> devm_add_action_or_reset() to register a disable function.

This is handled in lm75_remove() where I added the regulator_disable()
call.

Alban


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