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pwm: Add PWM capture support 

Supply a PWM capture callback op in order to pass back information
obtained by running analysis on a PWM 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@linaro.org>
[thierry.reding@gmail.com: make capture data unsigned int for symmetry]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
hifive-unleashed-5.1
Lee Jones 2016-06-08 10:21:23 +01:00 committed by Thierry Reding
parent 1a695a905c
commit 3a3d1a4e32
2 changed files with 51 additions and 0 deletions
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27
drivers/pwm/core.c
View File

@ -524,6 +524,33 @@ 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: structure to fill with capture result
* @timeout: 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 long timeout)
{
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);
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

24
include/linux/pwm.h
View File

@ -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 long timeout);
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 int period;
unsigned int duty_cycle;
};
#if IS_ENABLED(CONFIG_PWM)
/* PWM user APIs */
struct pwm_device *pwm_request(int pwm_id, const char *label);
@ -322,6 +337,8 @@ static inline void pwm_disable(struct pwm_device *pwm)
/* PWM provider APIs */
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
unsigned long timeout);
int pwm_set_chip_data(struct pwm_device *pwm, void *data);
void *pwm_get_chip_data(struct pwm_device *pwm);
@ -373,6 +390,13 @@ 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 long timeout)
{
return -EINVAL;
}
static inline int pwm_set_polarity(struct pwm_device *pwm,
enum pwm_polarity polarity)
{