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

Boris Brezillon
2016-06-03T08:23:11Z

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
@@ -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;
}

--
2.7.4