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-rw-r--r--drivers/pwm/core.c22
-rw-r--r--include/linux/pwm.h23
2 files changed, 45 insertions, 0 deletions
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index c6e05078d3ad..85592e97ef2d 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -379,6 +379,28 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
EXPORT_SYMBOL_GPL(pwm_config);
/**
+ * pwm_set_polarity() - configure the polarity of a PWM signal
+ * @pwm: PWM device
+ * @polarity: new polarity of the PWM signal
+ *
+ * Note that the polarity cannot be configured while the PWM device is enabled
+ */
+int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
+{
+ if (!pwm || !pwm->chip->ops)
+ return -EINVAL;
+
+ if (!pwm->chip->ops->set_polarity)
+ return -ENOSYS;
+
+ if (test_bit(PWMF_ENABLED, &pwm->flags))
+ return -EBUSY;
+
+ return pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
+}
+EXPORT_SYMBOL_GPL(pwm_set_polarity);
+
+/**
* pwm_enable() - start a PWM output toggling
* @pwm: PWM device
*/
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 21d076c5089e..354764cf5f7a 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -34,6 +34,20 @@ void pwm_disable(struct pwm_device *pwm);
#ifdef CONFIG_PWM
struct pwm_chip;
+/**
+ * enum pwm_polarity - polarity of a PWM signal
+ * @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
+ * cycle, followed by a low signal for the remainder of the pulse
+ * period
+ * @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
+ * cycle, followed by a high signal for the remainder of the pulse
+ * period
+ */
+enum pwm_polarity {
+ PWM_POLARITY_NORMAL,
+ PWM_POLARITY_INVERSED,
+};
+
enum {
PWMF_REQUESTED = 1 << 0,
PWMF_ENABLED = 1 << 1,
@@ -61,11 +75,17 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm)
return pwm ? pwm->period : 0;
}
+/*
+ * pwm_set_polarity - configure the polarity of a PWM signal
+ */
+int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);
+
/**
* struct pwm_ops - PWM controller operations
* @request: optional hook for requesting a PWM
* @free: optional hook for freeing a PWM
* @config: configure duty cycles and period length for this PWM
+ * @set_polarity: configure the polarity of this PWM
* @enable: enable PWM output toggling
* @disable: disable PWM output toggling
* @dbg_show: optional routine to show contents in debugfs
@@ -79,6 +99,9 @@ struct pwm_ops {
int (*config)(struct pwm_chip *chip,
struct pwm_device *pwm,
int duty_ns, int period_ns);
+ int (*set_polarity)(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ enum pwm_polarity polarity);
int (*enable)(struct pwm_chip *chip,
struct pwm_device *pwm);
void (*disable)(struct pwm_chip *chip,