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,