On Wed, Jun 08, 2016 at 10:21:23AM +0100, Lee Jones wrote: > Supply a PWM Capture call-back Op in order to pass back > information obtained by running analysis on PWM a signal. > This would normally (at least during testing) be called from > the Sysfs routines with a view to printing out PWM Capture > data which has been encoded into a string. > > Signed-off-by: Lee Jones <[email protected]> > --- > drivers/pwm/core.c | 27 +++++++++++++++++++++++++++ > include/linux/pwm.h | 25 +++++++++++++++++++++++++ > 2 files changed, 52 insertions(+) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index dba3843..4678de6 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -525,6 +525,33 @@ int pwm_apply_state(struct pwm_device *pwm, struct > pwm_state *state) > EXPORT_SYMBOL_GPL(pwm_apply_state); > > /** > + * pwm_capture() - capture and report a PWM signal > + * @pwm: PWM device > + * @result: struct to fill with capture result > + * @timeout_ms: time to wait, in milliseconds, before giving up on capture > + * > + * Returns: 0 on success or a negative error code on failure. > + */ > +int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result, > + unsigned int timeout_ms) > +{ > + int err; > + > + if (!pwm || !pwm->chip->ops) > + return -EINVAL; > + > + if (!pwm->chip->ops->capture) > + return -ENOSYS; > + > + mutex_lock(&pwm_lock); > + err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout_ms); > + mutex_unlock(&pwm_lock); > + > + return err; > +} > +EXPORT_SYMBOL_GPL(pwm_capture); > + > +/** > * pwm_adjust_config() - adjust the current PWM config to the PWM arguments > * @pwm: PWM device > * > diff --git a/include/linux/pwm.h b/include/linux/pwm.h > index 17018f3..13cac27 100644 > --- a/include/linux/pwm.h > +++ b/include/linux/pwm.h > @@ -5,7 +5,9 @@ > #include <linux/mutex.h> > #include <linux/of.h> > > +struct pwm_capture; > struct seq_file; > + > struct pwm_chip; > > /** > @@ -153,6 +155,7 @@ static inline void pwm_get_args(const struct pwm_device > *pwm, > * @free: optional hook for freeing a PWM > * @config: configure duty cycles and period length for this PWM > * @set_polarity: configure the polarity of this PWM > + * @capture: capture and report PWM signal > * @enable: enable PWM output toggling > * @disable: disable PWM output toggling > * @apply: atomically apply a new PWM config. The state argument > @@ -172,6 +175,8 @@ struct pwm_ops { > int duty_ns, int period_ns); > int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm, > enum pwm_polarity polarity); > + int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm, > + struct pwm_capture *result, unsigned int timeout_ms);
Can we please drop the _ms suffix. It's already documented to be in
milliseconds. Also maybe make that unsigned long for consistency with
the type of the timeout parameter elsewhere in the kernel.
> int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
> void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
> int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
> @@ -212,6 +217,16 @@ struct pwm_chip {
> bool can_sleep;
> };
>
> +/**
> + * struct pwm_capture - PWM capture data
> + * @period: period of the PWM signal (in nanoseconds)
> + * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
> + */
> +struct pwm_capture {
> + unsigned long long period;
> + unsigned long long duty_cycle;
> +};
I'd prefer these to be unsigned int, for symmetry with the PWM output
part of the framework. With 32 bits you get about 4.2 seconds of period
and duty cycle, and I doubt that any reasonable signal would extend
beyond that.
> @@ -322,6 +337,9 @@ static inline void pwm_disable(struct pwm_device *pwm)
>
>
> /* PWM provider APIs */
> +int pwm_capture(struct pwm_device *pwm,
> + struct pwm_capture *result,
> + unsigned int timeout_ms);
This fits into 2 lines. And same comments on the timeout parameter.
> int pwm_set_chip_data(struct pwm_device *pwm, void *data);
> void *pwm_get_chip_data(struct pwm_device *pwm);
>
> @@ -373,6 +391,13 @@ static inline int pwm_config(struct pwm_device *pwm, int
> duty_ns,
> return -EINVAL;
> }
>
> +static inline int pwm_capture(struct pwm_device *pwm,
> + struct pwm_capture *result,
> + unsigned int timeout_ms)
Same here.
Otherwise this looks really nice to me from an API point of view.
Thierry
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