From 3a3d1a4e32ab47323d7b8c8b7631a8d36a3098b2 Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Wed, 8 Jun 2016 10:21:23 +0100 Subject: 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 [thierry.reding@gmail.com: make capture data unsigned int for symmetry] Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'drivers') diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index dba3843c53b8..8f40604046d6 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -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 -- cgit v1.2.3 From 1a366fe9153f445e950a7a344932b7419aa83094 Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Wed, 8 Jun 2016 10:21:25 +0100 Subject: pwm: sysfs: Add PWM capture support Allow a user to read PWM capture results from sysfs. To start a capture and read the result, simply read the file: $ cat $PWMCHIP/capture The output format is " ". Signed-off-by: Lee Jones Signed-off-by: Thierry Reding --- Documentation/ABI/testing/sysfs-class-pwm | 9 +++++++++ drivers/pwm/sysfs.c | 17 +++++++++++++++++ 2 files changed, 26 insertions(+) (limited to 'drivers') diff --git a/Documentation/ABI/testing/sysfs-class-pwm b/Documentation/ABI/testing/sysfs-class-pwm index c479d77b67c5..c20e61354561 100644 --- a/Documentation/ABI/testing/sysfs-class-pwm +++ b/Documentation/ABI/testing/sysfs-class-pwm @@ -77,3 +77,12 @@ Description: Enable/disable the PWM signal. 0 is disabled 1 is enabled + +What: /sys/class/pwm/pwmchipN/pwmX/capture +Date: June 2016 +KernelVersion: 4.8 +Contact: Lee Jones +Description: + Capture information about a PWM signal. The output format is a + pair unsigned integers (period and duty cycle), separated by a + single space. diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index d98599249a05..c3b1b563480e 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -208,16 +208,33 @@ static ssize_t polarity_store(struct device *child, return ret ? : size; } +static ssize_t capture_show(struct device *child, + struct device_attribute *attr, + char *buf) +{ + struct pwm_device *pwm = child_to_pwm_device(child); + struct pwm_capture result; + int ret; + + ret = pwm_capture(pwm, &result, jiffies_to_msecs(HZ)); + if (ret) + return ret; + + return sprintf(buf, "%u %u\n", result.period, result.duty_cycle); +} + static DEVICE_ATTR_RW(period); static DEVICE_ATTR_RW(duty_cycle); static DEVICE_ATTR_RW(enable); static DEVICE_ATTR_RW(polarity); +static DEVICE_ATTR_RO(capture); static struct attribute *pwm_attrs[] = { &dev_attr_period.attr, &dev_attr_duty_cycle.attr, &dev_attr_enable.attr, &dev_attr_polarity.attr, + &dev_attr_capture.attr, NULL }; ATTRIBUTE_GROUPS(pwm); -- cgit v1.2.3