pwm: Add pwmchip_add_with_polarity() API

Add a new function to register a PWM chip with channels that have their
initial polarity as specified by an additional parameter. This benefits
drivers of controllers that by default operate with inversed polarity
by removing the need to modify the polarity during initialization.

Signed-off-by: Tim Kryger <tim.kryger@gmail.com>
Signed-off-by: Jonathan Richardson <jonathar@broadcom.com>
[thierry.reding@gmail.com: export pwmchip_add_with_polarity()]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index cfe2d8d..36262d0 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -182,6 +182,8 @@
 int pwm_set_chip_data(struct pwm_device *pwm, void *data);
 void *pwm_get_chip_data(struct pwm_device *pwm);
 
+int pwmchip_add_with_polarity(struct pwm_chip *chip,
+			      enum pwm_polarity polarity);
 int pwmchip_add(struct pwm_chip *chip);
 int pwmchip_remove(struct pwm_chip *chip);
 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
@@ -217,6 +219,11 @@
 	return -EINVAL;
 }
 
+static inline int pwmchip_add_inversed(struct pwm_chip *chip)
+{
+	return -EINVAL;
+}
+
 static inline int pwmchip_remove(struct pwm_chip *chip)
 {
 	return -EINVAL;