From: "Lai, Poey Seng" <poey.seng.lai@xxxxxxxxx>
In Keem Bay, the number of repetitions for the period/waveform
can be configured from userspace. This requires addition of a sysfs
attribute to get/set the repetition count. Setting this value to 0
will result in continuous repetition of the waveform until the
channel is disabled or reconfigured.
Signed-off-by: Lai, Poey Seng <poey.seng.lai@xxxxxxxxx>
Signed-off-by: Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@xxxxxxxxx>
---
Documentation/ABI/testing/sysfs-class-pwm | 9 ++++++++
drivers/pwm/core.c | 3 ++-
drivers/pwm/sysfs.c | 37 +++++++++++++++++++++++++++++++
include/linux/pwm.h | 2 ++
4 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-class-pwm b/Documentation/ABI/testing/sysfs-class-pwm
index c20e613..87e219f 100644
--- a/Documentation/ABI/testing/sysfs-class-pwm
+++ b/Documentation/ABI/testing/sysfs-class-pwm
@@ -86,3 +86,12 @@ Description:
Capture information about a PWM signal. The output format is a
pair unsigned integers (period and duty cycle), separated by a
single space.
+
+What: /sys/class/pwm/pwmchipN/pwmX/count
+Date: May 2020
+KernelVersion: 5.6
+Contact: Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@xxxxxxxxx>
+Description:
+ Sets the repetition count of a PWM waveform. A value of 0 will
+ result in continuous repetition of the waveform until the
+ channel is disabled or reconfigured.
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index bca0496..fd42fb6 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -584,7 +584,8 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)
if (state->period == pwm->state.period &&
state->duty_cycle == pwm->state.duty_cycle &&
state->polarity == pwm->state.polarity &&
- state->enabled == pwm->state.enabled)
+ state->enabled == pwm->state.enabled &&
+ state->count == pwm->state.count)
return 0;
if (chip->ops->apply) {
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 2389b86..3c474fa 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -215,11 +215,47 @@ static ssize_t capture_show(struct device *child,
return sprintf(buf, "%u %u\n", result.period, result.duty_cycle);
}
+static ssize_t count_store(struct device *child,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct pwm_export *export = child_to_pwm_export(child);
+ struct pwm_device *pwm = export->pwm;
+ struct pwm_state state;
+ unsigned int val;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ mutex_lock(&export->lock);
+ pwm_get_state(pwm, &state);
+ state.count = val;
+ ret = pwm_apply_state(pwm, &state);
+ mutex_unlock(&export->lock);
+
+ return ret ? : size;
+}
+
+static ssize_t count_show(struct device *child,
+ struct device_attribute *attr,
+ char *buf)
+{
+ const struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
+ return sprintf(buf, "%d\n", state.count);
+}
+
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 DEVICE_ATTR_RW(count);
static struct attribute *pwm_attrs[] = {
&dev_attr_period.attr,
@@ -227,6 +263,7 @@ static ssize_t capture_show(struct device *child,
&dev_attr_enable.attr,
&dev_attr_polarity.attr,
&dev_attr_capture.attr,
+ &dev_attr_count.attr,
NULL
};
ATTRIBUTE_GROUPS(pwm);
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 2635b2a..c874559 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -52,12 +52,14 @@ enum {
* struct pwm_state - state of a PWM channel
* @period: PWM period (in nanoseconds)
* @duty_cycle: PWM duty cycle (in nanoseconds)
+ * @count: Repeat count of PWM waveforms.
* @polarity: PWM polarity
* @enabled: PWM enabled status
*/
struct pwm_state {
unsigned int period;
unsigned int duty_cycle;
+ unsigned int count;
enum pwm_polarity polarity;
bool enabled;
};
--
1.9.1
