[PATCH 0/2] hwmon: ina3221: Add suspend and resume functions

[PATCH 0/2] hwmon: ina3221: Add suspend and resume functions

[Nicolin Chen]

This series of patches add system suspend and resume functiosn for
ina3221 hwmon driver.

Nicolin Chen (2):
  hwmon: ina3221: Add INA3221_CONFIG to volatile_table
  hwmon: ina3221: Add suspend and resume functions

 drivers/hwmon/ina3221.c | 56 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

-- 
2.17.1

[PATCH 1/2] hwmon: ina3221: Add INA3221_CONFIG to volatile_table

[Nicolin Chen]

The MSB (15th bit) of INA3221_CONFIG is a self-clear reset bit.
So this register should be added to the volatile_table of the
regmap_config. Otherwise, we will see this bit is sticky in the
regcache which might accidentally reset the chip when an actual
write happens to the register.

This might not be a severe bug for the current code line since
there's no second place touching the INA3221_CONFIG except the
reset routine in the probe().

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
 drivers/hwmon/ina3221.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index e6b49500c52a..cfe65ff01051 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -353,7 +353,7 @@ static struct attribute *ina3221_attrs[] = {
 ATTRIBUTE_GROUPS(ina3221);
 
 static const struct regmap_range ina3221_yes_ranges[] = {
-	regmap_reg_range(INA3221_SHUNT1, INA3221_BUS3),
+	regmap_reg_range(INA3221_CONFIG, INA3221_BUS3),
 	regmap_reg_range(INA3221_MASK_ENABLE, INA3221_MASK_ENABLE),
 };
 
-- 
2.17.1

[PATCH 2/2] hwmon: ina3221: Add suspend and resume functions

[Nicolin Chen]

Depending on the hardware design, an INA3221 chip might lose
its power during system suspend/resume. So this patch adds
a pair of suspend and resume functions to cache the register
values including config register value and limit settings.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
 drivers/hwmon/ina3221.c | 54 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index cfe65ff01051..26f66f728b27 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -91,11 +91,13 @@ static const unsigned int register_channel[] = {
  * @regmap: Register map of the device
  * @fields: Register fields of the device
  * @shunt_resistors: Array of resistor values per channel
+ * @reg_config: Register value of INA3221_CONFIG
  */
 struct ina3221_data {
 	struct regmap *regmap;
 	struct regmap_field *fields[F_MAX_FIELDS];
 	int shunt_resistors[INA3221_NUM_CHANNELS];
+	u32 reg_config;
 };
 
 static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
@@ -415,8 +417,59 @@ static int ina3221_probe(struct i2c_client *client,
 		return PTR_ERR(hwmon_dev);
 	}
 
+	dev_set_drvdata(dev, ina);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int ina3221_suspend(struct device *dev)
+{
+	struct ina3221_data *ina = dev_get_drvdata(dev);
+	int ret;
+
+	/* Save config register value and enable cache-only */
+	ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
+	if (ret)
+		return ret;
+
+	regcache_cache_only(ina->regmap, true);
+	regcache_mark_dirty(ina->regmap);
+
+	return 0;
+}
+
+static int ina3221_resume(struct device *dev)
+{
+	struct ina3221_data *ina = dev_get_drvdata(dev);
+	int ret;
+
+	regcache_cache_only(ina->regmap, false);
+
+	/* Software reset the chip */
+	ret = regmap_field_write(ina->fields[F_RST], true);
+	if (ret) {
+		dev_err(dev, "Unable to reset device\n");
+		return ret;
+	}
+
+	/* Restore cached register values to hardware */
+	ret = regcache_sync(ina->regmap);
+	if (ret)
+		return ret;
+
+	/* Restore config register value to hardware */
+	ret = regmap_write(ina->regmap, INA3221_CONFIG, ina->reg_config);
+	if (ret)
+		return ret;
+
 	return 0;
 }
+#endif
+
+static const struct dev_pm_ops ina3221_pm = {
+	SET_SYSTEM_SLEEP_PM_OPS(ina3221_suspend, ina3221_resume)
+};
 
 static const struct of_device_id ina3221_of_match_table[] = {
 	{ .compatible = "ti,ina3221", },
@@ -435,6 +488,7 @@ static struct i2c_driver ina3221_i2c_driver = {
 	.driver = {
 		.name = INA3221_DRIVER_NAME,
 		.of_match_table = ina3221_of_match_table,
+		.pm = &ina3221_pm,
 	},
 	.id_table = ina3221_ids,
 };
-- 
2.17.1

Re: [PATCH 2/2] hwmon: ina3221: Add suspend and resume functions

[Guenter Roeck]

On Fri, Sep 28, 2018 at 02:49:21PM -0700, Nicolin Chen wrote:
> Depending on the hardware design, an INA3221 chip might lose
> its power during system suspend/resume. So this patch adds
> a pair of suspend and resume functions to cache the register
> values including config register value and limit settings.
> 
> Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> ---
>  drivers/hwmon/ina3221.c | 54 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
> 
> diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> index cfe65ff01051..26f66f728b27 100644
> --- a/drivers/hwmon/ina3221.c
> +++ b/drivers/hwmon/ina3221.c
> @@ -91,11 +91,13 @@ static const unsigned int register_channel[] = {
>   * @regmap: Register map of the device
>   * @fields: Register fields of the device
>   * @shunt_resistors: Array of resistor values per channel
> + * @reg_config: Register value of INA3221_CONFIG
>   */
>  struct ina3221_data {
>  	struct regmap *regmap;
>  	struct regmap_field *fields[F_MAX_FIELDS];
>  	int shunt_resistors[INA3221_NUM_CHANNELS];
> +	u32 reg_config;
>  };
>  
>  static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
> @@ -415,8 +417,59 @@ static int ina3221_probe(struct i2c_client *client,
>  		return PTR_ERR(hwmon_dev);
>  	}
>  
> +	dev_set_drvdata(dev, ina);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int ina3221_suspend(struct device *dev)
> +{
> +	struct ina3221_data *ina = dev_get_drvdata(dev);
> +	int ret;
> +
> +	/* Save config register value and enable cache-only */
> +	ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
> +	if (ret)
> +		return ret;
> +

Would it make sense to explicitly disable all channels here ?

Thanks,
Guenter

> +	regcache_cache_only(ina->regmap, true);
> +	regcache_mark_dirty(ina->regmap);
> +
> +	return 0;
> +}
> +
> +static int ina3221_resume(struct device *dev)
> +{
> +	struct ina3221_data *ina = dev_get_drvdata(dev);
> +	int ret;
> +
> +	regcache_cache_only(ina->regmap, false);
> +
> +	/* Software reset the chip */
> +	ret = regmap_field_write(ina->fields[F_RST], true);
> +	if (ret) {
> +		dev_err(dev, "Unable to reset device\n");
> +		return ret;
> +	}
> +
> +	/* Restore cached register values to hardware */
> +	ret = regcache_sync(ina->regmap);
> +	if (ret)
> +		return ret;
> +
> +	/* Restore config register value to hardware */
> +	ret = regmap_write(ina->regmap, INA3221_CONFIG, ina->reg_config);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  }
> +#endif
> +
> +static const struct dev_pm_ops ina3221_pm = {
> +	SET_SYSTEM_SLEEP_PM_OPS(ina3221_suspend, ina3221_resume)
> +};
>  
>  static const struct of_device_id ina3221_of_match_table[] = {
>  	{ .compatible = "ti,ina3221", },
> @@ -435,6 +488,7 @@ static struct i2c_driver ina3221_i2c_driver = {
>  	.driver = {
>  		.name = INA3221_DRIVER_NAME,
>  		.of_match_table = ina3221_of_match_table,
> +		.pm = &ina3221_pm,
>  	},
>  	.id_table = ina3221_ids,
>  };
> -- 
> 2.17.1
> 

Re: [PATCH 2/2] hwmon: ina3221: Add suspend and resume functions

[Nicolin Chen]

On Sat, Sep 29, 2018 at 08:33:46AM -0700, Guenter Roeck wrote:
> On Fri, Sep 28, 2018 at 02:49:21PM -0700, Nicolin Chen wrote:
> > Depending on the hardware design, an INA3221 chip might lose
> > its power during system suspend/resume. So this patch adds
> > a pair of suspend and resume functions to cache the register
> > values including config register value and limit settings.
> > 
> > Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
> > ---
> >  drivers/hwmon/ina3221.c | 54 +++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 54 insertions(+)
> > 
> > diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> > index cfe65ff01051..26f66f728b27 100644
> > --- a/drivers/hwmon/ina3221.c
> > +++ b/drivers/hwmon/ina3221.c
> > @@ -91,11 +91,13 @@ static const unsigned int register_channel[] = {
> >   * @regmap: Register map of the device
> >   * @fields: Register fields of the device
> >   * @shunt_resistors: Array of resistor values per channel
> > + * @reg_config: Register value of INA3221_CONFIG
> >   */
> >  struct ina3221_data {
> >  	struct regmap *regmap;
> >  	struct regmap_field *fields[F_MAX_FIELDS];
> >  	int shunt_resistors[INA3221_NUM_CHANNELS];
> > +	u32 reg_config;
> >  };
> >  
> >  static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
> > @@ -415,8 +417,59 @@ static int ina3221_probe(struct i2c_client *client,
> >  		return PTR_ERR(hwmon_dev);
> >  	}
> >  
> > +	dev_set_drvdata(dev, ina);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_PM
> > +static int ina3221_suspend(struct device *dev)
> > +{
> > +	struct ina3221_data *ina = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	/* Save config register value and enable cache-only */
> > +	ret = regmap_read(ina->regmap, INA3221_CONFIG, &ina->reg_config);
> > +	if (ret)
> > +		return ret;
> > +
> 
> Would it make sense to explicitly disable all channels here ?

For power saving? I could add it to v2.

Thanks
Nicolin