Merge tag 'pwm/for-4.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm updates from Thierry Reding:
 "This set of changes introduces the beginnings of a new API that's
  based around the concept of states that can be atomically applied.
  Drivers go to various lengths to implement something similar, which
  indicates that the core should really be providing the necessary
  framework.

  On top of that, there is a bit of cleanup as well as improved
  kerneldoc and integration into the device-drivers DocBook.

  Regarding drivers there is a new one for the NXP LPC18xx family of
  SoCs and a couple of fixes for existing drivers (pca9685, Broadcom
  Kona and Atmel HLCDC)"

* tag 'pwm/for-4.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
  ARM: at91: pwm: atmel-hlcdc: Add at91sam9n12 errata
  pwm: Add NXP LPC18xx PWM/SCT DT binding documentation
  pwm: NXP LPC18xx PWM/SCT driver
  pwm-pca9685: Support changing the output frequency
  pwm-pca9685: Fix several driver bugs
  pwm: kona: Modify settings application sequence
  pwm: pca9685: Drop owner assignment
  pwm: Add to device-drivers documentation
  pwm: Clean up kerneldoc
  pwm: Remove useless whitespace
  pwm: sysfs: Remove unnecessary padding
  pwm: sysfs: Properly convert from enum to string
  pwm: Make use of pwm_get_xxx() helpers where appropriate
  pwm: Add pwm_get_polarity() helper function
  pwm: Constify PWM device where possible
  pwm: Add the pwm_is_enabled() helper

1 files changed, 88 insertions, 2 deletions

diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
index 34b5c275a92a..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)
@@ -85,6 +146,22 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	}
 
 	if (duty_ns == period_ns) {
+		/* Clear both OFF registers */
+		if (pwm->hwpwm >= PCA9685_MAXCHAN)
+			reg = PCA9685_ALL_LED_OFF_L;
+		else
+			reg = LED_N_OFF_L(pwm->hwpwm);
+
+		regmap_write(pca->regmap, reg, 0x0);
+
+		if (pwm->hwpwm >= PCA9685_MAXCHAN)
+			reg = PCA9685_ALL_LED_OFF_H;
+		else
+			reg = LED_N_OFF_H(pwm->hwpwm);
+
+		regmap_write(pca->regmap, reg, 0x0);
+
+		/* Set the full ON bit */
 		if (pwm->hwpwm >= PCA9685_MAXCHAN)
 			reg = PCA9685_ALL_LED_ON_H;
 		else
@@ -95,7 +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)
@@ -112,6 +189,14 @@ static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);
 
+	/* Clear the full ON bit, otherwise the set OFF time has no effect */
+	if (pwm->hwpwm >= PCA9685_MAXCHAN)
+		reg = PCA9685_ALL_LED_ON_H;
+	else
+		reg = LED_N_ON_H(pwm->hwpwm);
+
+	regmap_write(pca->regmap, reg, 0);
+
 	return 0;
 }
 
@@ -228,6 +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);
 
@@ -285,7 +372,6 @@ MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
 static struct i2c_driver pca9685_i2c_driver = {
 	.driver = {
 		.name = "pca9685-pwm",
-		.owner = THIS_MODULE,
 		.of_match_table = pca9685_dt_ids,
 	},
 	.probe = pca9685_pwm_probe,