diff options
| author | Lee Jones <lee.jones@linaro.org> | 2016-06-08 10:21:25 +0100 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2016-06-10 16:01:40 +0200 |
| commit | 1a366fe9153f445e950a7a344932b7419aa83094 (patch) | |
| tree | b6d66b37c862446d280a03179c178913d9090aad | |
| parent | 3a3d1a4e32ab47323d7b8c8b7631a8d36a3098b2 (diff) | |
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 "<period> <duty cycle>".
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-pwm | 9 | ||||
| -rw-r--r-- | drivers/pwm/sysfs.c | 17 |
2 files changed, 26 insertions, 0 deletions
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 <lee.jones@linaro.org> +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); |