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Commit ea398e28 authored by Boris Brezillon's avatar Boris Brezillon Committed by Thierry Reding
Browse files

regulator: pwm: Support extra continuous mode cases 



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: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: default avatarBrian Norris <briannorris@chromium.org>
Tested-by: default avatarBrian Norris <briannorris@chromium.org>
Tested-by: default avatarHeiko Stuebner <heiko@sntech.de>
Acked-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent d9070fdb

drivers/regulator/pwm-regulator.c

+82 −10
Original line number Diff line number Diff line
@@ -22,6 +22,12 @@ 
#include <linux/pwm.h>

#include <linux/gpio/consumer.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;
@@ -29,6 +35,9 @@ 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;
@@ -145,32 +154,78 @@ 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);



	/*

	 * The dutycycle for min_uV might be greater than the one for max_uV.

	 * This is happening when the user needs an inversed polarity, but the

	 * PWM device does not support inversing it in hardware.

	 */

	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;

	int old_uV = pwm_regulator_get_voltage(rdev);

	unsigned int diff_duty;

	unsigned int dutycycle;

	int ret;



	pwm_init_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);

	/*

	 * The dutycycle for min_uV might be greater than the one for max_uV.

	 * This is happening when the user needs an inversed polarity, but the

	 * PWM device does not support inversing it in hardware.

	 */

	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) {
@@ -182,7 +237,7 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev, 
		return 0;



	/* Ramp delay is in uV/uS. Adjust to uS and delay */

	ramp_delay = DIV_ROUND_UP(abs(min_uV - old_uV), ramp_delay);

	ramp_delay = DIV_ROUND_UP(abs(req_min_uV - old_uV), ramp_delay);

	usleep_range(ramp_delay, ramp_delay + DIV_ROUND_UP(ramp_delay, 10));



	return 0;
@@ -255,11 +310,28 @@ 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;

}