regulator: pwm-regulator: Add support for continuous-voltage

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>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index 25560fc519b757139fe868428ac827aec696cc12..dac145db305c77568ab29d46fb86477d9391a1d4 100644 (file)
--- 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);