Re: [PATCH v2 1/7] iio: imu: mpu6050: add support for regulator framework

[Brian Masney]

On Sat, Jul 21, 2018 at 06:31:07PM +0100, Jonathan Cameron wrote:
> On Tue, 17 Jul 2018 04:41:52 -0400
> Brian Masney <masneyb@xxxxxxxxxxxxx> wrote:
> 
> > This patch adds support for the regulator framework to the mpu6050
> > driver.
> > 
> > Signed-off-by: Brian Masney <masneyb@xxxxxxxxxxxxx>
> > Signed-off-by: Jonathan Marek <jonathan@xxxxxxxx>
> 
> I'm not 100% sure what the purpose of the regulator_enabled
> tracking is.  Perhaps you could point out the path where that is
> needed?

I was thinking about the use case where the device is compiled into the
kernel as a module, the device is suspended, and then someone rmmods
the module. If that is not a use case that I need to worry about, then
the flag can go away and it will simplify the code.

Brian



> Also, a missing bit of documentation needs adding.
> 
> Jonathan
> 
> > ---
> > Changes since v1:
> > - Use devm_regulator_get() instead of devm_regulator_get_optional()
> > - Use devm_add_action() for cleaning up the regulator.
> > - Correct ordering of resume code.
> > - Add regulator_enabled flag to ensure regulator is not disabled twice,
> >   specifically the case where the device is suspended and then the
> >   driver is removed.
> > 
> > Original extra changelog from v1:
> > 
> > This is a variation of Jonathan Marek's patch from postmarketOS
> > https://gitlab.com/postmarketOS/linux-postmarketos/commit/b8ad1ec1859c8bbcbce94944b3f4dd68f8f9fc37
> > with the following changes:
> > 
> > - Stripped out 6515 variant code.
> > - Add the regulator to the mpu core instead of only the i2c variant.
> > - Add error handling.
> > - Release the regulator on suspend, device remove, etc.
> > - Device tree documentation.
> > 
> >  .../bindings/iio/imu/inv_mpu6050.txt          |  1 +
> >  drivers/iio/imu/inv_mpu6050/inv_mpu_core.c    | 73 +++++++++++++++++++
> >  drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h     |  3 +
> >  3 files changed, 77 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/imu/inv_mpu6050.txt b/Documentation/devicetree/bindings/iio/imu/inv_mpu6050.txt
> > index b7def51c8ad9..d39907b12a46 100644
> > --- a/Documentation/devicetree/bindings/iio/imu/inv_mpu6050.txt
> > +++ b/Documentation/devicetree/bindings/iio/imu/inv_mpu6050.txt
> > @@ -21,6 +21,7 @@ Required properties:
> >    bindings.
> >  
> >  Optional properties:
> > + - vddio-supply: regulator phandle for VDDIO supply
> >   - mount-matrix: an optional 3x3 mounting rotation matrix
> >   - i2c-gate node.  These devices also support an auxiliary i2c bus.  This is
> >     simple enough to be described using the i2c-gate binding. See
> > diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> > index 12c1b9507007..e1fbab4bc0a0 100644
> > --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> > +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_core.c
> > @@ -23,6 +23,7 @@
> >  #include <linux/iio/iio.h>
> >  #include <linux/acpi.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/regulator/consumer.h>
> >  #include "inv_mpu_iio.h"
> >  
> >  /*
> > @@ -926,6 +927,46 @@ static int inv_check_and_setup_chip(struct inv_mpu6050_state *st)
> >  	return result;
> >  }
> >  
> > +static int inv_mpu_core_enable_regulator(struct inv_mpu6050_state *st)
> > +{
> > +	int result;
> > +
> > +	result = regulator_enable(st->vddio_supply);
> > +	if (result) {
> > +		dev_err(regmap_get_device(st->map),
> > +			"Failed to enable regulator: %d\n", result);
> > +	} else {
> > +		st->regulator_enabled = true;
> > +
> > +		/* Give the device a little bit of time to start up. */
> > +		usleep_range(35000, 70000);
> > +	}
> > +
> > +	return result;
> > +}
> > +
> > +static int inv_mpu_core_disable_regulator(struct inv_mpu6050_state *st)
> > +{
> > +	int result;
> > +
> > +	if (!st->regulator_enabled)
> > +		return 0;
> > +
> > +	result = regulator_disable(st->vddio_supply);
> > +	if (result)
> > +		dev_err(regmap_get_device(st->map),
> > +			"Failed to disable regulator: %d\n", result);
> > +
> > +	st->regulator_enabled = false;
> > +
> > +	return result;
> > +}
> > +
> > +static void inv_mpu_core_disable_regulator_action(void *_data)
> > +{
> > +	inv_mpu_core_disable_regulator(_data);
> > +}
> > +
> >  int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
> >  		int (*inv_mpu_bus_setup)(struct iio_dev *), int chip_type)
> >  {
> > @@ -990,6 +1031,28 @@ int inv_mpu_core_probe(struct regmap *regmap, int irq, const char *name,
> >  		return -EINVAL;
> >  	}
> >  
> > +	st->vddio_supply = devm_regulator_get(dev, "vddio");
> > +	if (IS_ERR(st->vddio_supply)) {
> > +		if (PTR_ERR(st->vddio_supply) != -EPROBE_DEFER)
> > +			dev_err(dev, "Failed to get vddio regulator %d\n",
> > +				(int)PTR_ERR(st->vddio_supply));
> > +
> > +		return PTR_ERR(st->vddio_supply);
> > +	}
> > +
> > +	result = inv_mpu_core_enable_regulator(st);
> > +	if (result)
> > +		return result;
> > +
> > +	result = devm_add_action(dev, inv_mpu_core_disable_regulator_action,
> > +				 st);
> > +	if (result) {
> > +		inv_mpu_core_disable_regulator_action(st);
> > +		dev_err(dev, "Failed to setup regulator cleanup action %d\n",
> > +			result);
> > +		return result;
> > +	}
> > +
> >  	/* power is turned on inside check chip type*/
> >  	result = inv_check_and_setup_chip(st);
> >  	if (result)
> > @@ -1049,7 +1112,12 @@ static int inv_mpu_resume(struct device *dev)
> >  	int result;
> >  
> >  	mutex_lock(&st->lock);
> > +	result = inv_mpu_core_enable_regulator(st);
> > +	if (result)
> > +		goto out_unlock;
> > +
> >  	result = inv_mpu6050_set_power_itg(st, true);
> > +out_unlock:
> >  	mutex_unlock(&st->lock);
> >  
> >  	return result;
> > @@ -1062,6 +1130,11 @@ static int inv_mpu_suspend(struct device *dev)
> >  
> >  	mutex_lock(&st->lock);
> >  	result = inv_mpu6050_set_power_itg(st, false);
> > +	if (result)
> > +		goto out_unlock;
> > +
> > +	result = inv_mpu_core_disable_regulator(st);
> > +out_unlock:
> >  	mutex_unlock(&st->lock);
> >  
> >  	return result;
> > diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
> > index e69a59659dbc..01c8fe9b4fa0 100644
> > --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
> > +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h
> > @@ -129,6 +129,7 @@ struct inv_mpu6050_hw {
> >   *  @chip_period:	chip internal period estimation (~1kHz).
> >   *  @it_timestamp:	timestamp from previous interrupt.
> >   *  @data_timestamp:	timestamp for next data sample.
> > + *  @vddio_supply	voltage regulator for the chip.
> Docs missing for regulator_enabled.
> >   */
> >  struct inv_mpu6050_state {
> >  	struct mutex lock;
> > @@ -149,6 +150,8 @@ struct inv_mpu6050_state {
> >  	s64 chip_period;
> >  	s64 it_timestamp;
> >  	s64 data_timestamp;
> > +	struct regulator *vddio_supply;
> > +	bool regulator_enabled;
> >  };
> >  
> >  /*register and associated bit definition*/