[PATCH 13/14] regulator: pwm: Support extra continuous mode cases
From: briannorris@chromium.org (Brian Norris)
Date: 2016-06-03 21:03:21
Also in:
linux-devicetree, linux-pwm, linux-rockchip, lkml
Hi Boris, On Fri, Jun 03, 2016 at 10:23:11AM +0200, Boris Brezillon wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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
...
quoted hunk ↗ jump to hunk
@@ -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) {
I still might have appreciated a comment above this line (and similar in set_voltage()) to help explain why max can be less than min -- you have it in the commit message, but nowhere in the code. Not a big deal, and the code looks otherwise good: Reviewed-by: Brian Norris <briannorris@chromium.org> Tested-by: Brian Norris <briannorris@chromium.org>
+ 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) {[...] Brian