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: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
index ae0bebbfda9db0a4b1809cd6447e0506719ab480..c24524242da2163a54d3a308bccb7912802a61ce 100644 (file)
--- a/drivers/regulator/pwm-regulator.c
+++ b/drivers/regulator/pwm-regulator.c
@@ -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;
 }