[13/14] regulator: pwm: Support extra continuous mode cases
diff mbox

Message ID 1464942192-25967-14-git-send-email-boris.brezillon@free-electrons.com
State New
Headers show

Commit Message

Boris BREZILLON June 3, 2016, 8:23 a.m. UTC
The continuous mode allows one to declare a PWM regulator without having
to declare the voltage <-> dutycycle association table. It works fine as
long as your voltage(dutycycle) function is linear, but also has the
following constraints:

- dutycycle for min_uV = 0%
- dutycycle for max_uV = 100%
- dutycycle for min_uV < dutycycle for max_uV

While the linearity constraint is acceptable for now, we sometimes need to
restrict of the PWM range (to limit the maximum/minimum voltage for
example) or have a min_uV_dutycycle > max_uV_dutycycle (this could be
tweaked with PWM polarity, but not all PWMs support inverted polarity).

Add the pwm-dutycycle-range and pwm-dutycycle-unit DT properties to define
such constraints. If those properties are not defined, the PWM regulator
use the default pwm-dutycycle-range = <0 100> and
pwm-dutycycle-unit = <100> values (existing behavior).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
---
 drivers/regulator/pwm-regulator.c | 80 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 71 insertions(+), 9 deletions(-)

Comments

Brian Norris June 3, 2016, 9:03 p.m. UTC | #1
Hi Boris,

On Fri, Jun 03, 2016 at 10:23:11AM +0200, Boris Brezillon wrote:
> The continuous mode allows one to declare a PWM regulator without having
> to declare the voltage <-> dutycycle association table. It works fine as
> long as your voltage(dutycycle) function is linear, but also has the
> following constraints:
> 
> - dutycycle for min_uV = 0%
> - dutycycle for max_uV = 100%
> - dutycycle for min_uV < dutycycle for max_uV
> 
> While the linearity constraint is acceptable for now, we sometimes need to
> restrict of the PWM range (to limit the maximum/minimum voltage for
> example) or have a min_uV_dutycycle > max_uV_dutycycle (this could be
> tweaked with PWM polarity, but not all PWMs support inverted polarity).
> 
> Add the pwm-dutycycle-range and pwm-dutycycle-unit DT properties to define
> such constraints. If those properties are not defined, the PWM regulator
> use the default pwm-dutycycle-range = <0 100> and
> pwm-dutycycle-unit = <100> values (existing behavior).
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> ---
>  drivers/regulator/pwm-regulator.c | 80 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 71 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
> index c39ecd1..2e70eb1 100644
> --- a/drivers/regulator/pwm-regulator.c
> +++ b/drivers/regulator/pwm-regulator.c

...

> @@ -132,31 +141,67 @@ static int pwm_regulator_is_enabled(struct regulator_dev *dev)
>  static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
>  {
>  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> +	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
> +	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
> +	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
>  	int min_uV = rdev->constraints->min_uV;
> -	int diff = rdev->constraints->max_uV - min_uV;
> +	int max_uV = rdev->constraints->max_uV;
> +	int diff_uV = max_uV - min_uV;
>  	struct pwm_state pstate;
> +	unsigned int diff_duty;
> +	unsigned int voltage;
>  
>  	pwm_get_state(drvdata->pwm, &pstate);
>  
> -	return min_uV + pwm_get_relative_duty_cycle(&pstate, diff);
> +	voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit);
> +
> +	if (max_uV_duty < min_uV_duty) {

I still might have appreciated a comment above this line (and similar
in set_voltage()) to help explain why max can be less than min -- you
have it in the commit message, but nowhere in the code. Not a big deal,
and the code looks otherwise good:

Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>


> +		voltage = min_uV_duty - voltage;
> +		diff_duty = min_uV_duty - max_uV_duty;
> +	} else {
> +		voltage = voltage - min_uV_duty;
> +		diff_duty = max_uV_duty - min_uV_duty;
> +	}
> +
> +	voltage = DIV_ROUND_CLOSEST_ULL((u64)voltage * diff_uV, diff_duty);
> +
> +	return voltage + min_uV;
>  }
>  
>  static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
> -					int min_uV, int max_uV,
> -					unsigned *selector)
> +				     int req_min_uV, int req_max_uV,
> +				     unsigned int *selector)
>  {
>  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> +	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
> +	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
> +	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
>  	unsigned int ramp_delay = rdev->constraints->ramp_delay;
> -	unsigned int req_diff = min_uV - rdev->constraints->min_uV;
> +	int min_uV = rdev->constraints->min_uV;
> +	int max_uV = rdev->constraints->max_uV;
> +	int diff_uV = max_uV - min_uV;
>  	struct pwm_state pstate;
> -	unsigned int diff;
> +	unsigned int diff_duty;
> +	unsigned int dutycycle;
>  	int ret;
>  
>  	pwm_prepare_new_state(drvdata->pwm, &pstate);
> -	diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
>  
> -	/* We pass diff as the scale to get a uV precision. */
> -	pwm_set_relative_duty_cycle(&pstate, req_diff, diff);
> +	if (max_uV_duty < min_uV_duty)
> +		diff_duty = min_uV_duty - max_uV_duty;
> +	else
> +		diff_duty = max_uV_duty - min_uV_duty;
> +
> +	dutycycle = DIV_ROUND_CLOSEST_ULL((u64)(req_min_uV - min_uV) *
> +					  diff_duty,
> +					  diff_uV);
> +
> +	if (max_uV_duty < min_uV_duty)
> +		dutycycle = min_uV_duty - dutycycle;
> +	else
> +		dutycycle = min_uV_duty + dutycycle;
> +
> +	pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit);
>  
>  	ret = pwm_apply_state(drvdata->pwm, &pstate);
>  	if (ret) {

[...]

Brian
Boris BREZILLON June 4, 2016, 6:30 a.m. UTC | #2
On Fri, 3 Jun 2016 14:03:08 -0700
Brian Norris <briannorris@chromium.org> wrote:

> Hi Boris,
> 
> On Fri, Jun 03, 2016 at 10:23:11AM +0200, Boris Brezillon wrote:
> > The continuous mode allows one to declare a PWM regulator without having
> > to declare the voltage <-> dutycycle association table. It works fine as
> > long as your voltage(dutycycle) function is linear, but also has the
> > following constraints:
> > 
> > - dutycycle for min_uV = 0%
> > - dutycycle for max_uV = 100%
> > - dutycycle for min_uV < dutycycle for max_uV
> > 
> > While the linearity constraint is acceptable for now, we sometimes need to
> > restrict of the PWM range (to limit the maximum/minimum voltage for
> > example) or have a min_uV_dutycycle > max_uV_dutycycle (this could be
> > tweaked with PWM polarity, but not all PWMs support inverted polarity).
> > 
> > Add the pwm-dutycycle-range and pwm-dutycycle-unit DT properties to define
> > such constraints. If those properties are not defined, the PWM regulator
> > use the default pwm-dutycycle-range = <0 100> and
> > pwm-dutycycle-unit = <100> values (existing behavior).
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > ---
> >  drivers/regulator/pwm-regulator.c | 80 ++++++++++++++++++++++++++++++++++-----
> >  1 file changed, 71 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
> > index c39ecd1..2e70eb1 100644
> > --- a/drivers/regulator/pwm-regulator.c
> > +++ b/drivers/regulator/pwm-regulator.c  
> 
> ...
> 
> > @@ -132,31 +141,67 @@ static int pwm_regulator_is_enabled(struct regulator_dev *dev)
> >  static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
> >  {
> >  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> > +	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
> > +	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
> > +	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
> >  	int min_uV = rdev->constraints->min_uV;
> > -	int diff = rdev->constraints->max_uV - min_uV;
> > +	int max_uV = rdev->constraints->max_uV;
> > +	int diff_uV = max_uV - min_uV;
> >  	struct pwm_state pstate;
> > +	unsigned int diff_duty;
> > +	unsigned int voltage;
> >  
> >  	pwm_get_state(drvdata->pwm, &pstate);
> >  
> > -	return min_uV + pwm_get_relative_duty_cycle(&pstate, diff);
> > +	voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit);
> > +
> > +	if (max_uV_duty < min_uV_duty) {  
> 
> I still might have appreciated a comment above this line (and similar
> in set_voltage()) to help explain why max can be less than min -- you
> have it in the commit message, but nowhere in the code. Not a big deal,
> and the code looks otherwise good:

Sure, I'll add more comments in the next version.

Thanks,

Boris

> 
> Reviewed-by: Brian Norris <briannorris@chromium.org>
> Tested-by: Brian Norris <briannorris@chromium.org>
> 
> 
> > +		voltage = min_uV_duty - voltage;
> > +		diff_duty = min_uV_duty - max_uV_duty;
> > +	} else {
> > +		voltage = voltage - min_uV_duty;
> > +		diff_duty = max_uV_duty - min_uV_duty;
> > +	}
> > +
> > +	voltage = DIV_ROUND_CLOSEST_ULL((u64)voltage * diff_uV, diff_duty);
> > +
> > +	return voltage + min_uV;
> >  }
> >  
> >  static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
> > -					int min_uV, int max_uV,
> > -					unsigned *selector)
> > +				     int req_min_uV, int req_max_uV,
> > +				     unsigned int *selector)
> >  {
> >  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> > +	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
> > +	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
> > +	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
> >  	unsigned int ramp_delay = rdev->constraints->ramp_delay;
> > -	unsigned int req_diff = min_uV - rdev->constraints->min_uV;
> > +	int min_uV = rdev->constraints->min_uV;
> > +	int max_uV = rdev->constraints->max_uV;
> > +	int diff_uV = max_uV - min_uV;
> >  	struct pwm_state pstate;
> > -	unsigned int diff;
> > +	unsigned int diff_duty;
> > +	unsigned int dutycycle;
> >  	int ret;
> >  
> >  	pwm_prepare_new_state(drvdata->pwm, &pstate);
> > -	diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
> >  
> > -	/* We pass diff as the scale to get a uV precision. */
> > -	pwm_set_relative_duty_cycle(&pstate, req_diff, diff);
> > +	if (max_uV_duty < min_uV_duty)
> > +		diff_duty = min_uV_duty - max_uV_duty;
> > +	else
> > +		diff_duty = max_uV_duty - min_uV_duty;
> > +
> > +	dutycycle = DIV_ROUND_CLOSEST_ULL((u64)(req_min_uV - min_uV) *
> > +					  diff_duty,
> > +					  diff_uV);
> > +
> > +	if (max_uV_duty < min_uV_duty)
> > +		dutycycle = min_uV_duty - dutycycle;
> > +	else
> > +		dutycycle = min_uV_duty + dutycycle;
> > +
> > +	pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit);
> >  
> >  	ret = pwm_apply_state(drvdata->pwm, &pstate);
> >  	if (ret) {  
> 
> [...]
> 
> Brian

Patch
diff mbox

diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index c39ecd1..2e70eb1 100644
--- a/drivers/regulator/pwm-regulator.c
+++ b/drivers/regulator/pwm-regulator.c
@@ -21,6 +21,12 @@ 
 #include <linux/of_device.h>
 #include <linux/pwm.h>
 
+struct pwm_continuous_reg_data {
+	unsigned int min_uV_dutycycle;
+	unsigned int max_uV_dutycycle;
+	unsigned int dutycycle_unit;
+};
+
 struct pwm_regulator_data {
 	/*  Shared */
 	struct pwm_device *pwm;
@@ -28,6 +34,9 @@  struct pwm_regulator_data {
 	/* Voltage table */
 	struct pwm_voltages *duty_cycle_table;
 
+	/* Continuous mode info */
+	struct pwm_continuous_reg_data continuous;
+
 	/* regulator descriptor */
 	struct regulator_desc desc;
 
@@ -132,31 +141,67 @@  static int pwm_regulator_is_enabled(struct regulator_dev *dev)
 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
 {
 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
+	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
+	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
+	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
 	int min_uV = rdev->constraints->min_uV;
-	int diff = rdev->constraints->max_uV - min_uV;
+	int max_uV = rdev->constraints->max_uV;
+	int diff_uV = max_uV - min_uV;
 	struct pwm_state pstate;
+	unsigned int diff_duty;
+	unsigned int voltage;
 
 	pwm_get_state(drvdata->pwm, &pstate);
 
-	return min_uV + pwm_get_relative_duty_cycle(&pstate, diff);
+	voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit);
+
+	if (max_uV_duty < min_uV_duty) {
+		voltage = min_uV_duty - voltage;
+		diff_duty = min_uV_duty - max_uV_duty;
+	} else {
+		voltage = voltage - min_uV_duty;
+		diff_duty = max_uV_duty - min_uV_duty;
+	}
+
+	voltage = DIV_ROUND_CLOSEST_ULL((u64)voltage * diff_uV, diff_duty);
+
+	return voltage + min_uV;
 }
 
 static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
-					int min_uV, int max_uV,
-					unsigned *selector)
+				     int req_min_uV, int req_max_uV,
+				     unsigned int *selector)
 {
 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
+	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
+	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
+	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
 	unsigned int ramp_delay = rdev->constraints->ramp_delay;
-	unsigned int req_diff = min_uV - rdev->constraints->min_uV;
+	int min_uV = rdev->constraints->min_uV;
+	int max_uV = rdev->constraints->max_uV;
+	int diff_uV = max_uV - min_uV;
 	struct pwm_state pstate;
-	unsigned int diff;
+	unsigned int diff_duty;
+	unsigned int dutycycle;
 	int ret;
 
 	pwm_prepare_new_state(drvdata->pwm, &pstate);
-	diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
 
-	/* We pass diff as the scale to get a uV precision. */
-	pwm_set_relative_duty_cycle(&pstate, req_diff, diff);
+	if (max_uV_duty < min_uV_duty)
+		diff_duty = min_uV_duty - max_uV_duty;
+	else
+		diff_duty = max_uV_duty - min_uV_duty;
+
+	dutycycle = DIV_ROUND_CLOSEST_ULL((u64)(req_min_uV - min_uV) *
+					  diff_duty,
+					  diff_uV);
+
+	if (max_uV_duty < min_uV_duty)
+		dutycycle = min_uV_duty - dutycycle;
+	else
+		dutycycle = min_uV_duty + dutycycle;
+
+	pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit);
 
 	ret = pwm_apply_state(drvdata->pwm, &pstate);
 	if (ret) {
@@ -237,11 +282,28 @@  static int pwm_regulator_init_table(struct platform_device *pdev,
 static int pwm_regulator_init_continuous(struct platform_device *pdev,
 					 struct pwm_regulator_data *drvdata)
 {
+	u32 dutycycle_range[2] = { 0, 100 };
+	u32 dutycycle_unit = 100;
+
 	memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
 	       sizeof(drvdata->ops));
 	drvdata->desc.ops = &drvdata->ops;
 	drvdata->desc.continuous_voltage_range = true;
 
+	of_property_read_u32_array(pdev->dev.of_node,
+				   "pwm-dutycycle-range",
+				   dutycycle_range, 2);
+	of_property_read_u32(pdev->dev.of_node, "pwm-dutycycle-unit",
+			     &dutycycle_unit);
+
+	if (dutycycle_range[0] > dutycycle_unit ||
+	    dutycycle_range[1] > dutycycle_unit)
+		return -EINVAL;
+
+	drvdata->continuous.dutycycle_unit = dutycycle_unit;
+	drvdata->continuous.min_uV_dutycycle = dutycycle_range[0];
+	drvdata->continuous.max_uV_dutycycle = dutycycle_range[1];
+
 	return 0;
 }