| Message ID | 1521607244-29734-2-git-send-email-rrajk@nvidia.com |
|---|---|
| State | Deferred |
| Headers | show |
| Series | Implementation of Tegra Tachometer driver | expand |
On Wed, Mar 21, 2018 at 10:10:36AM +0530, Rajkumar Rampelli wrote: > Add support for pwm HW driver which has only capture functionality. > This helps to implement the PWM based Tachometer driver which reads > the PWM output signals from electronic fans. > > PWM Tachometer captures the period and duty cycle of the PWM signal > > Add conditional checks for callabacks enable(), disable(), config() > to check if they are supported by the client driver or not. Skip these > callbacks if they are not supported. > > Signed-off-by: Rajkumar Rampelli <rrajk@nvidia.com> > --- > > V2: Added if conditional checks for pwm callbacks since drivers may > implements only pwm capture functionality. > > drivers/pwm/core.c | 21 +++++++++++++++------ > 1 file changed, 15 insertions(+), 6 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 1581f6a..f70fe68 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -246,6 +246,10 @@ static bool pwm_ops_check(const struct pwm_ops *ops) > if (ops->apply) > return true; > > + /* driver supports capture operation */ > + if (ops->capture) > + return true; > + > return false; > } > > @@ -495,7 +499,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) > * ->apply(). > */ > if (pwm->state.enabled) { > - pwm->chip->ops->disable(pwm->chip, pwm); > + if (pwm->chip->ops->disable) > + pwm->chip->ops->disable(pwm->chip, pwm); This is not a good idea. It means that you'll be able to successfully configure a capture-only PWM channel for output. I think all of the output configuration functions should return an error (-ENOSYS?) for capture-only devices, much like we return -ENOSYS for pwm_capture() if the driver doesn't implement capture support. Thierry
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 1581f6a..f70fe68 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -246,6 +246,10 @@ static bool pwm_ops_check(const struct pwm_ops *ops) if (ops->apply) return true; + /* driver supports capture operation */ + if (ops->capture) + return true; + return false; } @@ -495,7 +499,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) * ->apply(). */ if (pwm->state.enabled) { - pwm->chip->ops->disable(pwm->chip, pwm); + if (pwm->chip->ops->disable) + pwm->chip->ops->disable(pwm->chip, pwm); pwm->state.enabled = false; } @@ -509,22 +514,26 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state) if (state->period != pwm->state.period || state->duty_cycle != pwm->state.duty_cycle) { - err = pwm->chip->ops->config(pwm->chip, pwm, + if (pwm->chip->ops->config) { + err = pwm->chip->ops->config(pwm->chip, pwm, state->duty_cycle, state->period); - if (err) - return err; + if (err) + return err; + } pwm->state.duty_cycle = state->duty_cycle; pwm->state.period = state->period; } if (state->enabled != pwm->state.enabled) { - if (state->enabled) { + if (state->enabled && pwm->chip->ops->enable) { err = pwm->chip->ops->enable(pwm->chip, pwm); if (err) return err; - } else { + } + + if (!state->enabled && pwm->chip->ops->disable) { pwm->chip->ops->disable(pwm->chip, pwm); }
Add support for pwm HW driver which has only capture functionality. This helps to implement the PWM based Tachometer driver which reads the PWM output signals from electronic fans. PWM Tachometer captures the period and duty cycle of the PWM signal Add conditional checks for callabacks enable(), disable(), config() to check if they are supported by the client driver or not. Skip these callbacks if they are not supported. Signed-off-by: Rajkumar Rampelli <rrajk@nvidia.com> --- V2: Added if conditional checks for pwm callbacks since drivers may implements only pwm capture functionality. drivers/pwm/core.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-)