Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1a366fe9 authored by Lee Jones's avatar Lee Jones Committed by Thierry Reding
Browse files

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: default avatarLee Jones <lee.jones@linaro.org>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 3a3d1a4e

Documentation/ABI/testing/sysfs-class-pwm

+9 −0
Original line number Diff line number Diff line
@@ -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.

drivers/pwm/sysfs.c

+17 −0
Original line number Diff line number Diff line
@@ -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);