From 1a366fe9153f445e950a7a344932b7419aa83094 Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Wed, 8 Jun 2016 10:21:25 +0100 Subject: [PATCH] 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(+) 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); -- 2.20.1