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 <lee.jones@xxxxxxxxxx>
> ---
> 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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