From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Norris Subject: Re: [PATCH 13/14] regulator: pwm: Support extra continuous mode cases Date: Fri, 3 Jun 2016 14:03:08 -0700 Message-ID: <20160603210308.GK124478@google.com> References: <1464942192-25967-1-git-send-email-boris.brezillon@free-electrons.com> <1464942192-25967-14-git-send-email-boris.brezillon@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1464942192-25967-14-git-send-email-boris.brezillon@free-electrons.com> Sender: linux-pwm-owner@vger.kernel.org To: Boris Brezillon Cc: Thierry Reding , linux-pwm@vger.kernel.org, Mark Brown , Liam Girdwood , Heiko Stuebner , linux-rockchip@lists.infradead.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Milo Kim , Doug Anderson , Caesar Wang , Stephen Barber , Srinivas Kandagatla , Maxime Coquelin , Patrice Chotard , kernel@stlinux.com List-Id: devicetree@vger.kernel.org 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 > --- > 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: Reviewed-by: Brian Norris Tested-by: Brian Norris > + 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