[PATCH v2 7/9] regulator: pwm-regulator: Add support for continuous-voltage

Lee Jones
2015-07-07T15:08:28Z

The current version of PWM regulator only supports a static table
approach, where pre-calculated values are supplied by the vendor and
obtained via DT. The continuous-voltage method takes min_uV and
max_uV, and divides the difference between them up into a number of
slices. The number of slices depend on how large the duty cycle
register is. This information is provided by a DT property.

As the name alludes, this provides values for a continuous voltage
range between min_uV and max_uV, which has obvious benefits over
either limited voltage possibilities, or the requirement to provide
a large voltage-table.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
drivers/regulator/pwm-regulator.c | 114 +++++++++++++++++++++++++++++++++++---
1 file changed, 106 insertions(+), 8 deletions(-)

diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index 25560fc..dac145d 100644
--- a/drivers/regulator/pwm-regulator.c
+++ b/drivers/regulator/pwm-regulator.c
@@ -10,6 +10,7 @@
* published by the Free Software Foundation.
*/

+#include <linux/delay.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
@@ -21,9 +22,16 @@
#include <linux/pwm.h>

struct pwm_regulator_data {
- struct pwm_voltages *duty_cycle_table;
+ /* Shared */
struct pwm_device *pwm;
+
+ /* Voltage table */
+ struct pwm_voltages *duty_cycle_table;
int state;
+
+ /* Continuous voltage */
+ u32 max_duty_cycle;
+ int volt_uV;
};

struct pwm_voltages {
@@ -31,6 +39,9 @@ struct pwm_voltages {
unsigned int dutycycle;
};

+/**
+ * Voltage table call-backs
+ */
static int pwm_regulator_get_voltage_sel(struct regulator_dev *rdev)
{
struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
@@ -78,6 +89,71 @@ static int pwm_regulator_list_voltage(struct regulator_dev *rdev,

return drvdata->duty_cycle_table[selector].uV;
}
+
+/**
+ * Continuous voltage call-backs
+ */
+static int pwm_voltage_to_duty_cycle(struct regulator_dev *rdev,
+ int volt_mV)
+{
+ struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
+ int min_mV = rdev->constraints->min_uV / 1000;
+ int max_mV = rdev->constraints->max_uV / 1000;
+ int max_duty_cycle = drvdata->max_duty_cycle;
+ int vdiff = min_mV - max_mV;
+ int pwm_code;
+ int tmp;
+
+ tmp = ((max_duty_cycle - min_mV) * max_duty_cycle) / vdiff;
+ pwm_code = ((tmp + max_duty_cycle) * volt_mV) / vdiff;
+
+ if (pwm_code < 0)
+ pwm_code = 0;
+ if (pwm_code > max_duty_cycle)
+ pwm_code = max_duty_cycle;
+
+ return pwm_code * 100 / max_duty_cycle;
+}
+
+static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
+{
+ struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
+
+ return drvdata->volt_uV;
+}
+
+static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
+ int min_uV, int max_uV,
+ unsigned *selector)
+{
+ struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
+ unsigned int ramp_delay = rdev->constraints->ramp_delay;
+ int duty_cycle;
+ int ret;
+
+ duty_cycle = pwm_voltage_to_duty_cycle(rdev, min_uV / 1000);
+
+ ret = pwm_config(drvdata->pwm,
+ (drvdata->pwm->period / 100) * duty_cycle,
+ drvdata->pwm->period);
+ if (ret) {
+ dev_err(&rdev->dev, "Failed to configure PWM\n");
+ return ret;
+ }
+
+ ret = pwm_enable(drvdata->pwm);
+ if (ret) {
+ dev_err(&rdev->dev, "Failed to enable PWM\n");
+ return ret;
+ }
+ drvdata->volt_uV = min_uV;
+
+ /* Delay required by PWM regulator to settle to the new voltage */
+ usleep_range(ramp_delay, ramp_delay + 1000);
+
+ return 0;
+}
+
static struct regulator_ops pwm_regulator_voltage_table_ops = {
.set_voltage_sel = pwm_regulator_set_voltage_sel,
.get_voltage_sel = pwm_regulator_get_voltage_sel,
@@ -85,6 +161,11 @@ static struct regulator_ops pwm_regulator_voltage_table_ops = {
.map_voltage = regulator_map_voltage_iterate,
};

+static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
+ .get_voltage = pwm_regulator_get_voltage,
+ .set_voltage = pwm_regulator_set_voltage,
+};
+
static struct regulator_desc pwm_regulator_desc = {
.name = "pwm-regulator",
.type = REGULATOR_VOLTAGE,
@@ -129,6 +210,25 @@ static int pwm_regulator_init_table(struct platform_device *pdev,
return 0;
}

+static int pwm_regulator_init_continuous(struct platform_device *pdev,
+ struct pwm_regulator_data *drvdata)
+{
+ struct device_node *np = pdev->dev.of_node;
+ int ret;
+
+ ret = of_property_read_u32(np, "max-duty-cycle",
+ &drvdata->max_duty_cycle);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to read \"pwm-max-value\"\n");
+ return ret;
+ }
+
+ pwm_regulator_desc.ops = &pwm_regulator_voltage_continuous_ops;
+ pwm_regulator_desc.continuous_voltage_range = true;
+
+ return 0;
+}
+
static int pwm_regulator_probe(struct platform_device *pdev)
{
struct pwm_regulator_data *drvdata;
@@ -146,14 +246,12 @@ static int pwm_regulator_probe(struct platform_device *pdev)
if (!drvdata)
return -ENOMEM;

- if (of_find_property(np, "voltage-table", NULL)) {
+ if (of_find_property(np, "voltage-table", NULL))
ret = pwm_regulator_init_table(pdev, drvdata);
- if (ret)
- return ret;
- } else {
- dev_err(&pdev->dev, "No \"voltage-table\" supplied\n");
- return -EINVAL;
- }
+ else
+ ret = pwm_regulator_init_continuous(pdev, drvdata);
+ if (ret)
+ return ret;

config.init_data = of_get_regulator_init_data(&pdev->dev, np,
&pwm_regulator_desc);
--
1.9.1