On Fri, 3 Jun 2016 14:03:08 -0700 Brian Norris <[email protected]> wrote:
> Hi Boris, > > On Fri, Jun 03, 2016 at 10:23:11AM +0200, Boris Brezillon wrote: > > 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 <[email protected]> > > --- > > 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 > > ... > > > @@ -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: Sure, I'll add more comments in the next version. Thanks, Boris > > Reviewed-by: Brian Norris <[email protected]> > Tested-by: Brian Norris <[email protected]> > > > > + 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 -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
