diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 0d17d99b749b..70448a6079b0 100644
--- a/drivers/pwm/pwm-pca9685.c
+++ b/drivers/pwm/pwm-pca9685.c
@@ -2,6 +2,7 @@
  * Driver for PCA9685 16-channel 12-bit PWM LED controller
  *
  * Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
+ * Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
  *
  * based on the pwm-twl-led.c driver
  *
@@ -24,6 +25,15 @@
 #include <linux/pwm.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
+
+/*
+ * Because the PCA9685 has only one prescaler per chip, changing the period of
+ * one channel affects the period of all 16 PWM outputs!
+ * However, the ratio between each configured duty cycle and the chip-wide
+ * period remains constant, because the OFF time is set in proportion to the
+ * counter range.
+ */
 
 #define PCA9685_MODE1		0x00
 #define PCA9685_MODE2		0x01
@@ -42,10 +52,18 @@
 #define PCA9685_ALL_LED_OFF_H	0xFD
 #define PCA9685_PRESCALE	0xFE
 
+#define PCA9685_PRESCALE_MIN	0x03	/* => max. frequency of 1526 Hz */
+#define PCA9685_PRESCALE_MAX	0xFF	/* => min. frequency of 24 Hz */
+
+#define PCA9685_COUNTER_RANGE	4096
+#define PCA9685_DEFAULT_PERIOD	5000000	/* Default period_ns = 1/200 Hz */
+#define PCA9685_OSC_CLOCK_MHZ	25	/* Internal oscillator with 25 MHz */
+
 #define PCA9685_NUMREGS		0xFF
 #define PCA9685_MAXCHAN		0x10
 
 #define LED_FULL		(1 << 4)
+#define MODE1_RESTART		(1 << 7)
 #define MODE1_SLEEP		(1 << 4)
 #define MODE2_INVRT		(1 << 4)
 #define MODE2_OUTDRV		(1 << 2)
@@ -59,6 +77,8 @@ struct pca9685 {
 	struct pwm_chip chip;
 	struct regmap *regmap;
 	int active_cnt;
+	int duty_ns;
+	int period_ns;
 };
 
 static inline struct pca9685 *to_pca(struct pwm_chip *chip)
@@ -72,6 +92,47 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	struct pca9685 *pca = to_pca(chip);
 	unsigned long long duty;
 	unsigned int reg;
+	int prescale;
+
+	if (period_ns != pca->period_ns) {
+		prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
+					     PCA9685_COUNTER_RANGE * 1000) - 1;
+
+		if (prescale >= PCA9685_PRESCALE_MIN &&
+			prescale <= PCA9685_PRESCALE_MAX) {
+			/* Put chip into sleep mode */
+			regmap_update_bits(pca->regmap, PCA9685_MODE1,
+					   MODE1_SLEEP, MODE1_SLEEP);
+
+			/* Change the chip-wide output frequency */
+			regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);
+
+			/* Wake the chip up */
+			regmap_update_bits(pca->regmap, PCA9685_MODE1,
+					   MODE1_SLEEP, 0x0);
+
+			/* Wait 500us for the oscillator to be back up */
+			udelay(500);
+
+			pca->period_ns = period_ns;
+
+			/*
+			 * If the duty cycle did not change, restart PWM with
+			 * the same duty cycle to period ratio and return.
+			 */
+			if (duty_ns == pca->duty_ns) {
+				regmap_update_bits(pca->regmap, PCA9685_MODE1,
+						   MODE1_RESTART, 0x1);
+				return 0;
+			}
+		} else {
+			dev_err(chip->dev,
+				"prescaler not set: period out of bounds!\n");
+			return -EINVAL;
+		}
+	}
+
+	pca->duty_ns = duty_ns;
 
 	if (duty_ns < 1) {
 		if (pwm->hwpwm >= PCA9685_MAXCHAN)
@@ -111,7 +172,7 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		return 0;
 	}
 
-	duty = 4096 * (unsigned long long)duty_ns;
+	duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
 	duty = DIV_ROUND_UP_ULL(duty, period_ns);
 
 	if (pwm->hwpwm >= PCA9685_MAXCHAN)
@@ -252,6 +313,8 @@ static int pca9685_pwm_probe(struct i2c_client *client,
 			ret);
 		return ret;
 	}
+	pca->duty_ns = 0;
+	pca->period_ns = PCA9685_DEFAULT_PERIOD;
 
 	i2c_set_clientdata(client, pca);