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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>
This commit is contained in:
Lee Jones 2015-07-07 16:06:51 +01:00 committed by Mark Brown
parent 02258b8bcb
commit 4773be185a
1 changed files with 106 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

114
drivers/regulator/pwm-regulator.c
View File

@ -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);