[[PATCH v2] 03/11] pwm: sysfs: Add PWM Capture support

From: Lee Jones
Date: Fri Apr 22 2016 - 06:18:30 EST


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@xxxxxxxxxx>
---
drivers/pwm/sysfs.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 9c90886..ca0d886 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -167,16 +167,33 @@ 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, "%llu %llu\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);
--
2.8.0