Merge tag 'pwm/for-4.3-rc1' of...

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

Documentation/DocBook/device-drivers.tmpl

@@ -490,4 +490,31 @@ X!Ilib/fonts/fonts.c
 !Edrivers/hsi/hsi.c
   </chapter>
 
+  <chapter id="pwm">
+    <title>Pulse-Width Modulation (PWM)</title>
+    <para>
+      Pulse-width modulation is a modulation technique primarily used to
+      control power supplied to electrical devices.
+    </para>
+    <para>
+      The PWM framework provides an abstraction for providers and consumers
+      of PWM signals. A controller that provides one or more PWM signals is
+      registered as <structname>struct pwm_chip</structname>. Providers are
+      expected to embed this structure in a driver-specific structure. This
+      structure contains fields that describe a particular chip.
+    </para>
+    <para>
+      A chip exposes one or more PWM signal sources, each of which exposed
+      as a <structname>struct pwm_device</structname>. Operations can be
+      performed on PWM devices to control the period, duty cycle, polarity
+      and active state of the signal.
+    </para>
+    <para>
+      Note that PWM devices are exclusive resources: they can always only be
+      used by one consumer at a time.
+    </para>
+!Iinclude/linux/pwm.h
+!Edrivers/pwm/core.c
+  </chapter>
+
 </book>

Documentation/devicetree/bindings/pwm/lpc1850-sct-pwm.txt

+* NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
+
+Required properties:
+  - compatible: Should be "nxp,lpc1850-sct-pwm"
+  - reg: Should contain physical base address and length of pwm registers.
+  - clocks: Must contain an entry for each entry in clock-names.
+    See ../clock/clock-bindings.txt for details.
+  - clock-names: Must include the following entries.
+    - pwm: PWM operating clock.
+  - #pwm-cells: Should be 3. See pwm.txt in this directory for the description
+    of the cells format.
+
+Example:
+  pwm: pwm@40000000 {
+    compatible = "nxp,lpc1850-sct-pwm";
+    reg = <0x40000000 0x1000>;
+    clocks =<&ccu1 CLK_CPU_SCT>;
+    clock-names = "pwm";
+    #pwm-cells = <3>;
+  };

drivers/pwm/Kconfig

@@ -180,6 +180,18 @@ config PWM_LP3943
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lp3943.
 
+config PWM_LPC18XX_SCT
+	tristate "LPC18xx/43xx PWM/SCT support"
+	depends on ARCH_LPC18XX
+	help
+	  Generic PWM framework driver for NXP LPC18xx PWM/SCT which
+	  supports 16 channels.
+	  A maximum of 15 channels can be requested simultaneously and
+	  must have the same period.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-lpc18xx-sct.
+
 config PWM_LPC32XX
 	tristate "LPC32XX PWM support"
 	depends on ARCH_LPC32XX

drivers/pwm/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_LP3943)	+= pwm-lp3943.o
+obj-$(CONFIG_PWM_LPC18XX_SCT)	+= pwm-lpc18xx-sct.o
 obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o

drivers/pwm/core.c

@@ -200,6 +200,8 @@ static void of_pwmchip_remove(struct pwm_chip *chip)
  * pwm_set_chip_data() - set private chip data for a PWM
  * @pwm: PWM device
  * @data: pointer to chip-specific data
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwm_set_chip_data(struct pwm_device *pwm, void *data)
 {
@@ -215,6 +217,8 @@ EXPORT_SYMBOL_GPL(pwm_set_chip_data);
 /**
  * pwm_get_chip_data() - get private chip data for a PWM
  * @pwm: PWM device
+ *
+ * Returns: A pointer to the chip-private data for the PWM device.
  */
 void *pwm_get_chip_data(struct pwm_device *pwm)
 {
@@ -230,6 +234,8 @@ EXPORT_SYMBOL_GPL(pwm_get_chip_data);
  * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
  * will be used. The initial polarity for all channels is specified by the
  * @polarity parameter.
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwmchip_add_with_polarity(struct pwm_chip *chip,
 			      enum pwm_polarity polarity)
@@ -291,6 +297,8 @@ EXPORT_SYMBOL_GPL(pwmchip_add_with_polarity);
  *
  * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
  * will be used. The initial polarity for all channels is normal.
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwmchip_add(struct pwm_chip *chip)
 {
@@ -304,6 +312,8 @@ EXPORT_SYMBOL_GPL(pwmchip_add);
  *
  * Removes a PWM chip. This function may return busy if the PWM chip provides
  * a PWM device that is still requested.
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwmchip_remove(struct pwm_chip *chip)
 {
@@ -338,10 +348,13 @@ EXPORT_SYMBOL_GPL(pwmchip_remove);
 
 /**
  * pwm_request() - request a PWM device
- * @pwm_id: global PWM device index
+ * @pwm: global PWM device index
  * @label: PWM device label
  *
  * This function is deprecated, use pwm_get() instead.
+ *
+ * Returns: A pointer to a PWM device or an ERR_PTR()-encoded error code on
+ * failure.
  */
 struct pwm_device *pwm_request(int pwm, const char *label)
 {
@@ -376,9 +389,9 @@ EXPORT_SYMBOL_GPL(pwm_request);
  * @index: per-chip index of the PWM to request
  * @label: a literal description string of this PWM
  *
- * Returns the PWM at the given index of the given PWM chip. A negative error
- * code is returned if the index is not valid for the specified PWM chip or
- * if the PWM device cannot be requested.
+ * Returns: A pointer to the PWM device at the given index of the given PWM
+ * chip. A negative error code is returned if the index is not valid for the
+ * specified PWM chip or if the PWM device cannot be requested.
  */
 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 					 unsigned int index,
@@ -419,6 +432,8 @@ EXPORT_SYMBOL_GPL(pwm_free);
  * @pwm: PWM device
  * @duty_ns: "on" time (in nanoseconds)
  * @period_ns: duration (in nanoseconds) of one cycle
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 {
@@ -443,7 +458,10 @@ EXPORT_SYMBOL_GPL(pwm_config);
  * @pwm: PWM device
  * @polarity: new polarity of the PWM signal
  *
- * Note that the polarity cannot be configured while the PWM device is enabled
+ * Note that the polarity cannot be configured while the PWM device is
+ * enabled.
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
 {
@@ -455,7 +473,7 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
 	if (!pwm->chip->ops->set_polarity)
 		return -ENOSYS;
 
-	if (test_bit(PWMF_ENABLED, &pwm->flags))
+	if (pwm_is_enabled(pwm))
 		return -EBUSY;
 
 	err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity);
@@ -471,6 +489,8 @@ EXPORT_SYMBOL_GPL(pwm_set_polarity);
 /**
  * pwm_enable() - start a PWM output toggling
  * @pwm: PWM device
+ *
+ * Returns: 0 on success or a negative error code on failure.
  */
 int pwm_enable(struct pwm_device *pwm)
 {
@@ -524,6 +544,9 @@ static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
  * lookup of the PWM index. This also means that the "pwm-names" property
  * becomes mandatory for devices that look up the PWM device via the con_id
  * parameter.
+ *
+ * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
+ * error code on failure.
  */
 struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
 {
@@ -630,6 +653,9 @@ void pwm_remove_table(struct pwm_lookup *table, size_t num)
  *
  * Once a PWM chip has been found the specified PWM device will be requested
  * and is ready to be used.
+ *
+ * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
+ * error code on failure.
  */
 struct pwm_device *pwm_get(struct device *dev, const char *con_id)
 {
@@ -752,6 +778,9 @@ static void devm_pwm_release(struct device *dev, void *res)
  *
  * This function performs like pwm_get() but the acquired PWM device will
  * automatically be released on driver detach.
+ *
+ * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
+ * error code on failure.
  */
 struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id)
 {
@@ -781,6 +810,9 @@ EXPORT_SYMBOL_GPL(devm_pwm_get);
  *
  * This function performs like of_pwm_get() but the acquired PWM device will
  * automatically be released on driver detach.
+ *
+ * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
+ * error code on failure.
  */
 struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
 				   const char *con_id)
@@ -832,7 +864,7 @@ EXPORT_SYMBOL_GPL(devm_pwm_put);
   * pwm_can_sleep() - report whether PWM access will sleep
   * @pwm: PWM device
   *
-  * It returns true if accessing the PWM can sleep, false otherwise.
+  * Returns: True if accessing the PWM can sleep, false otherwise.
   */
 bool pwm_can_sleep(struct pwm_device *pwm)
 {
@@ -853,7 +885,7 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 		if (test_bit(PWMF_REQUESTED, &pwm->flags))
 			seq_puts(s, " requested");
 
-		if (test_bit(PWMF_ENABLED, &pwm->flags))
+		if (pwm_is_enabled(pwm))
 			seq_puts(s, " enabled");
 
 		seq_puts(s, "\n");
@@ -924,6 +956,5 @@ static int __init pwm_debugfs_init(void)
 
 	return 0;
 }
-
 subsys_initcall(pwm_debugfs_init);
 #endif /* CONFIG_DEBUG_FS */

drivers/pwm/pwm-atmel-hlcdc.c

@@ -217,6 +217,11 @@ static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_sama5d3_errata = {
 };
 
 static const struct of_device_id atmel_hlcdc_dt_ids[] = {
+	{
+		.compatible = "atmel,at91sam9n12-hlcdc",
+		/* 9n12 has same errata as 9x5 HLCDC PWM */
+		.data = &atmel_hlcdc_pwm_at91sam9x5_errata,
+	},
 	{
 		.compatible = "atmel,at91sam9x5-hlcdc",
 		.data = &atmel_hlcdc_pwm_at91sam9x5_errata,

drivers/pwm/pwm-atmel-tcb.c

@@ -347,7 +347,7 @@ static int atmel_tcb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	tcbpwm->duty = duty;
 
 	/* If the PWM is enabled, call enable to apply the new conf */
-	if (test_bit(PWMF_ENABLED, &pwm->flags))
+	if (pwm_is_enabled(pwm))
 		atmel_tcb_pwm_enable(chip, pwm);
 
 	return 0;

drivers/pwm/pwm-atmel.c

@@ -114,7 +114,7 @@ static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	u32 val;
 	int ret;
 
-	if (test_bit(PWMF_ENABLED, &pwm->flags) && (period_ns != pwm->period)) {
+	if (pwm_is_enabled(pwm) && (period_ns != pwm_get_period(pwm))) {
 		dev_err(chip->dev, "cannot change PWM period while enabled\n");
 		return -EBUSY;
 	}
@@ -176,7 +176,7 @@ static void atmel_pwm_config_v1(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * If the PWM channel is enabled, only update CDTY by using the update
 	 * register, it needs to set bit 10 of CMR to 0
 	 */
-	if (test_bit(PWMF_ENABLED, &pwm->flags))
+	if (pwm_is_enabled(pwm))
 		return;
 	/*
 	 * If the PWM channel is disabled, write value to duty and period
@@ -191,7 +191,7 @@ static void atmel_pwm_config_v2(struct pwm_chip *chip, struct pwm_device *pwm,
 {
 	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
 
-	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (pwm_is_enabled(pwm)) {
 		/*
 		 * If the PWM channel is enabled, using the duty update register
 		 * to update the value.

drivers/pwm/pwm-bcm-kona.c

@@ -76,19 +76,36 @@ static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *_chip)
 	return container_of(_chip, struct kona_pwmc, chip);
 }
 
-static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan)
+/*
+ * Clear trigger bit but set smooth bit to maintain old output.
+ */
+static void kona_pwmc_prepare_for_settings(struct kona_pwmc *kp,
+	unsigned int chan)
 {
 	unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
 
-	/* Clear trigger bit but set smooth bit to maintain old output */
 	value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan);
 	value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan));
 	writel(value, kp->base + PWM_CONTROL_OFFSET);
 
+	/*
+	 * There must be a min 400ns delay between clearing trigger and setting
+	 * it. Failing to do this may result in no PWM signal.
+	 */
+	ndelay(400);
+}
+
+static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan)
+{
+	unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);
+
 	/* Set trigger bit and clear smooth bit to apply new settings */
 	value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan));
 	value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan);
 	writel(value, kp->base + PWM_CONTROL_OFFSET);
+
+	/* Trigger bit must be held high for at least 400 ns. */
+	ndelay(400);
 }
 
 static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
@@ -133,8 +150,14 @@ static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm,
 			return -EINVAL;
 	}
 
-	/* If the PWM channel is enabled, write the settings to the HW */
-	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+	/*
+	 * Don't apply settings if disabled. The period and duty cycle are
+	 * always calculated above to ensure the new values are
+	 * validated immediately instead of on enable.
+	 */
+	if (pwm_is_enabled(pwm)) {
+		kona_pwmc_prepare_for_settings(kp, chan);
+
 		value = readl(kp->base + PRESCALE_OFFSET);
 		value &= ~PRESCALE_MASK(chan);
 		value |= prescale << PRESCALE_SHIFT(chan);
@@ -164,6 +187,8 @@ static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 		return ret;
 	}
 
+	kona_pwmc_prepare_for_settings(kp, chan);
+
 	value = readl(kp->base + PWM_CONTROL_OFFSET);
 
 	if (polarity == PWM_POLARITY_NORMAL)
@@ -175,9 +200,6 @@ static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	kona_pwmc_apply_settings(kp, chan);
 
-	/* Wait for waveform to settle before gating off the clock */
-	ndelay(400);
-
 	clk_disable_unprepare(kp->clk);
 
 	return 0;
@@ -194,7 +216,8 @@ static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 		return ret;
 	}
 
-	ret = kona_pwmc_config(chip, pwm, pwm->duty_cycle, pwm->period);
+	ret = kona_pwmc_config(chip, pwm, pwm_get_duty_cycle(pwm),
+			       pwm_get_period(pwm));
 	if (ret < 0) {
 		clk_disable_unprepare(kp->clk);
 		return ret;
@@ -207,13 +230,20 @@ static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct kona_pwmc *kp = to_kona_pwmc(chip);
 	unsigned int chan = pwm->hwpwm;
+	unsigned int value;
+
+	kona_pwmc_prepare_for_settings(kp, chan);
 
 	/* Simulate a disable by configuring for zero duty */
 	writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
-	kona_pwmc_apply_settings(kp, chan);
+	writel(0, kp->base + PERIOD_COUNT_OFFSET(chan));
 
-	/* Wait for waveform to settle before gating off the clock */
-	ndelay(400);
+	/* Set prescale to 0 for this channel */
+	value = readl(kp->base + PRESCALE_OFFSET);
+	value &= ~PRESCALE_MASK(chan);
+	writel(value, kp->base + PRESCALE_OFFSET);
+
+	kona_pwmc_apply_settings(kp, chan);
 
 	clk_disable_unprepare(kp->clk);
 }
@@ -287,7 +317,7 @@ static int kona_pwmc_remove(struct platform_device *pdev)
 	unsigned int chan;
 
 	for (chan = 0; chan < kp->chip.npwm; chan++)
-		if (test_bit(PWMF_ENABLED, &kp->chip.pwms[chan].flags))
+		if (pwm_is_enabled(&kp->chip.pwms[chan]))
 			clk_disable_unprepare(kp->clk);
 
 	return pwmchip_remove(&kp->chip);

drivers/pwm/pwm-ep93xx.c

@@ -82,7 +82,7 @@ static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * The clock needs to be enabled to access the PWM registers.
 	 * Configuration can be changed at any time.
 	 */
-	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (!pwm_is_enabled(pwm)) {
 		ret = clk_enable(ep93xx_pwm->clk);
 		if (ret)
 			return ret;
@@ -113,7 +113,7 @@ static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		ret = -EINVAL;
 	}
 
-	if (!test_bit(PWMF_ENABLED, &pwm->flags))
+	if (!pwm_is_enabled(pwm))
 		clk_disable(ep93xx_pwm->clk);
 
 	return ret;

drivers/pwm/pwm-imx.c

@@ -114,7 +114,7 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
 	unsigned long long c;
 	unsigned long period_cycles, duty_cycles, prescale;
 	unsigned int period_ms;
-	bool enable = test_bit(PWMF_ENABLED, &pwm->flags);
+	bool enable = pwm_is_enabled(pwm);
 	int wait_count = 0, fifoav;
 	u32 cr, sr;
 
@@ -129,7 +129,8 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
 		sr = readl(imx->mmio_base + MX3_PWMSR);
 		fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
 		if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
-			period_ms = DIV_ROUND_UP(pwm->period, NSEC_PER_MSEC);
+			period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
+						 NSEC_PER_MSEC);
 			msleep(period_ms);
 
 			sr = readl(imx->mmio_base + MX3_PWMSR);

drivers/pwm/pwm-mxs.c

@@ -77,7 +77,7 @@ static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * If the PWM channel is disabled, make sure to turn on the clock
 	 * before writing the register. Otherwise, keep it enabled.
 	 */
-	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (!pwm_is_enabled(pwm)) {
 		ret = clk_prepare_enable(mxs->clk);
 		if (ret)
 			return ret;
@@ -92,7 +92,7 @@ static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	/*
 	 * If the PWM is not enabled, turn the clock off again to save power.
 	 */
-	if (!test_bit(PWMF_ENABLED, &pwm->flags))
+	if (!pwm_is_enabled(pwm))
 		clk_disable_unprepare(mxs->clk);
 
 	return 0;

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,

drivers/pwm/pwm-renesas-tpu.c

@@ -301,7 +301,7 @@ static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *_pwm,
 	pwm->duty = duty;
 
 	/* If the channel is disabled we're done. */
-	if (!test_bit(PWMF_ENABLED, &_pwm->flags))
+	if (!pwm_is_enabled(_pwm))
 		return 0;
 
 	if (duty_only && pwm->timer_on) {

drivers/pwm/pwm-rockchip.c

@@ -83,7 +83,7 @@ static void rockchip_pwm_set_enable_v2(struct pwm_chip *chip,
 			  PWM_CONTINUOUS;
 	u32 val;
 
-	if (pwm->polarity == PWM_POLARITY_INVERSED)
+	if (pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED)
 		enable_conf |= PWM_DUTY_NEGATIVE | PWM_INACTIVE_POSITIVE;
 	else
 		enable_conf |= PWM_DUTY_POSITIVE | PWM_INACTIVE_NEGATIVE;

drivers/pwm/pwm-tegra.c

@@ -112,7 +112,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	 * If the PWM channel is disabled, make sure to turn on the clock
 	 * before writing the register. Otherwise, keep it enabled.
 	 */
-	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (!pwm_is_enabled(pwm)) {
 		err = clk_prepare_enable(pc->clk);
 		if (err < 0)
 			return err;
@@ -124,7 +124,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 	/*
 	 * If the PWM is not enabled, turn the clock off again to save power.
 	 */
-	if (!test_bit(PWMF_ENABLED, &pwm->flags))
+	if (!pwm_is_enabled(pwm))
 		clk_disable_unprepare(pc->clk);
 
 	return 0;
@@ -214,7 +214,7 @@ static int tegra_pwm_remove(struct platform_device *pdev)
 	for (i = 0; i < NUM_PWM; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];
 
-		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+		if (!pwm_is_enabled(pwm))
 			if (clk_prepare_enable(pc->clk) < 0)
 				continue;
 

drivers/pwm/pwm-tiecap.c

@@ -97,7 +97,7 @@ static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	writew(reg_val, pc->mmio_base + ECCTL2);
 
-	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (!pwm_is_enabled(pwm)) {
 		/* Update active registers if not running */
 		writel(duty_cycles, pc->mmio_base + CAP2);
 		writel(period_cycles, pc->mmio_base + CAP1);
@@ -111,7 +111,7 @@ static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 		writel(period_cycles, pc->mmio_base + CAP3);
 	}
 
-	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (!pwm_is_enabled(pwm)) {
 		reg_val = readw(pc->mmio_base + ECCTL2);
 		/* Disable APWM mode to put APWM output Low */
 		reg_val &= ~ECCTL2_APWM_MODE;
@@ -179,7 +179,7 @@ static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 
 static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
-	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (pwm_is_enabled(pwm)) {
 		dev_warn(chip->dev, "Removing PWM device without disabling\n");
 		pm_runtime_put_sync(chip->dev);
 	}
@@ -306,7 +306,7 @@ static int ecap_pwm_suspend(struct device *dev)
 	ecap_pwm_save_context(pc);
 
 	/* Disable explicitly if PWM is running */
-	if (test_bit(PWMF_ENABLED, &pwm->flags))
+	if (pwm_is_enabled(pwm))
 		pm_runtime_put_sync(dev);
 
 	return 0;
@@ -318,7 +318,7 @@ static int ecap_pwm_resume(struct device *dev)
 	struct pwm_device *pwm = pc->chip.pwms;
 
 	/* Enable explicitly if PWM was running */
-	if (test_bit(PWMF_ENABLED, &pwm->flags))
+	if (pwm_is_enabled(pwm))
 		pm_runtime_get_sync(dev);
 
 	ecap_pwm_restore_context(pc);

drivers/pwm/pwm-tiehrpwm.c

@@ -407,7 +407,7 @@ static void ehrpwm_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
 
-	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
+	if (pwm_is_enabled(pwm)) {
 		dev_warn(chip->dev, "Removing PWM device without disabling\n");
 		pm_runtime_put_sync(chip->dev);
 	}
@@ -565,7 +565,7 @@ static int ehrpwm_pwm_suspend(struct device *dev)
 	for (i = 0; i < pc->chip.npwm; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];
 
-		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+		if (!pwm_is_enabled(pwm))
 			continue;
 
 		/* Disable explicitly if PWM is running */
@@ -582,7 +582,7 @@ static int ehrpwm_pwm_resume(struct device *dev)
 	for (i = 0; i < pc->chip.npwm; i++) {
 		struct pwm_device *pwm = &pc->chip.pwms[i];
 
-		if (!test_bit(PWMF_ENABLED, &pwm->flags))
+		if (!pwm_is_enabled(pwm))
 			continue;
 
 		/* Enable explicitly if PWM was running */

drivers/pwm/sysfs.c

@@ -46,7 +46,7 @@ static ssize_t pwm_period_show(struct device *child,
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
 
-	return sprintf(buf, "%u\n", pwm->period);
+	return sprintf(buf, "%u\n", pwm_get_period(pwm));
 }
 
 static ssize_t pwm_period_store(struct device *child,
@@ -61,7 +61,7 @@ static ssize_t pwm_period_store(struct device *child,
 	if (ret)
 		return ret;
 
-	ret = pwm_config(pwm, pwm->duty_cycle, val);
+	ret = pwm_config(pwm, pwm_get_duty_cycle(pwm), val);
 
 	return ret ? : size;
 }
@@ -72,7 +72,7 @@ static ssize_t pwm_duty_cycle_show(struct device *child,
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
 
-	return sprintf(buf, "%u\n", pwm->duty_cycle);
+	return sprintf(buf, "%u\n", pwm_get_duty_cycle(pwm));
 }
 
 static ssize_t pwm_duty_cycle_store(struct device *child,
@@ -87,7 +87,7 @@ static ssize_t pwm_duty_cycle_store(struct device *child,
 	if (ret)
 		return ret;
 
-	ret = pwm_config(pwm, val, pwm->period);
+	ret = pwm_config(pwm, val, pwm_get_period(pwm));
 
 	return ret ? : size;
 }
@@ -97,7 +97,7 @@ static ssize_t pwm_enable_show(struct device *child,
 			       char *buf)
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
-	int enabled = test_bit(PWMF_ENABLED, &pwm->flags);
+	int enabled = pwm_is_enabled(pwm);
 
 	return sprintf(buf, "%d\n", enabled);
 }
@@ -133,8 +133,19 @@ static ssize_t pwm_polarity_show(struct device *child,
 				 char *buf)
 {
 	const struct pwm_device *pwm = child_to_pwm_device(child);
+	const char *polarity = "unknown";
 
-	return sprintf(buf, "%s\n", pwm->polarity ? "inversed" : "normal");
+	switch (pwm_get_polarity(pwm)) {
+	case PWM_POLARITY_NORMAL:
+		polarity = "normal";
+		break;
+
+	case PWM_POLARITY_INVERSED:
+		polarity = "inversed";
+		break;
+	}
+
+	return sprintf(buf, "%s\n", polarity);
 }
 
 static ssize_t pwm_polarity_store(struct device *child,
@@ -301,9 +312,9 @@ static struct attribute *pwm_chip_attrs[] = {
 ATTRIBUTE_GROUPS(pwm_chip);
 
 static struct class pwm_class = {
-	.name		= "pwm",
-	.owner		= THIS_MODULE,
-	.dev_groups	= pwm_chip_groups,
+	.name = "pwm",
+	.owner = THIS_MODULE,
+	.dev_groups = pwm_chip_groups,
 };
 
 static int pwmchip_sysfs_match(struct device *parent, const void *data)

include/linux/pwm.h

@@ -79,26 +79,43 @@ enum {
 	PWMF_EXPORTED = 1 << 2,
 };
 
+/**
+ * struct pwm_device - PWM channel object
+ * @label: name of the PWM device
+ * @flags: flags associated with the PWM device
+ * @hwpwm: per-chip relative index of the PWM device
+ * @pwm: global index of the PWM device
+ * @chip: PWM chip providing this PWM device
+ * @chip_data: chip-private data associated with the PWM device
+ * @period: period of the PWM signal (in nanoseconds)
+ * @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
+ * @polarity: polarity of the PWM signal
+ */
 struct pwm_device {
-	const char		*label;
-	unsigned long		flags;
-	unsigned int		hwpwm;
-	unsigned int		pwm;
-	struct pwm_chip		*chip;
-	void			*chip_data;
-
-	unsigned int		period; 	/* in nanoseconds */
-	unsigned int		duty_cycle;	/* in nanoseconds */
-	enum pwm_polarity	polarity;
+	const char *label;
+	unsigned long flags;
+	unsigned int hwpwm;
+	unsigned int pwm;
+	struct pwm_chip *chip;
+	void *chip_data;
+
+	unsigned int period;
+	unsigned int duty_cycle;
+	enum pwm_polarity polarity;
 };
 
+static inline bool pwm_is_enabled(const struct pwm_device *pwm)
+{
+	return test_bit(PWMF_ENABLED, &pwm->flags);
+}
+
 static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
 {
 	if (pwm)
 		pwm->period = period;
 }
 
-static inline unsigned int pwm_get_period(struct pwm_device *pwm)
+static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
 {
 	return pwm ? pwm->period : 0;
 }
@@ -109,7 +126,7 @@ static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
 		pwm->duty_cycle = duty;
 }
 
-static inline unsigned int pwm_get_duty_cycle(struct pwm_device *pwm)
+static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
 {
 	return pwm ? pwm->duty_cycle : 0;
 }
@@ -119,6 +136,11 @@ static inline unsigned int pwm_get_duty_cycle(struct pwm_device *pwm)
  */
 int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);
 
+static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
+{
+	return pwm ? pwm->polarity : PWM_POLARITY_NORMAL;
+}
+
 /**
  * struct pwm_ops - PWM controller operations
  * @request: optional hook for requesting a PWM
@@ -131,25 +153,18 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity);
  * @owner: helps prevent removal of modules exporting active PWMs
  */
 struct pwm_ops {
-	int			(*request)(struct pwm_chip *chip,
-					   struct pwm_device *pwm);
-	void			(*free)(struct pwm_chip *chip,
-					struct pwm_device *pwm);
-	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,
-					   struct pwm_device *pwm);
+	int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
+	void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
+	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, struct pwm_device *pwm);
 #ifdef CONFIG_DEBUG_FS
-	void			(*dbg_show)(struct pwm_chip *chip,
-					    struct seq_file *s);
+	void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
 #endif
-	struct module		*owner;
+	struct module *owner;
 };
 
 /**
@@ -160,22 +175,24 @@ struct pwm_ops {
  * @base: number of first PWM controlled by this chip
  * @npwm: number of PWMs controlled by this chip
  * @pwms: array of PWM devices allocated by the framework
+ * @of_xlate: request a PWM device given a device tree PWM specifier
+ * @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
  * @can_sleep: must be true if the .config(), .enable() or .disable()
  *             operations may sleep
  */
 struct pwm_chip {
-	struct device		*dev;
-	struct list_head	list;
-	const struct pwm_ops	*ops;
-	int			base;
-	unsigned int		npwm;
-
-	struct pwm_device	*pwms;
-
-	struct pwm_device *	(*of_xlate)(struct pwm_chip *pc,
-					    const struct of_phandle_args *args);
-	unsigned int		of_pwm_n_cells;
-	bool			can_sleep;
+	struct device *dev;
+	struct list_head list;
+	const struct pwm_ops *ops;
+	int base;
+	unsigned int npwm;
+
+	struct pwm_device *pwms;
+
+	struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
+					const struct of_phandle_args *args);
+	unsigned int of_pwm_n_cells;
+	bool can_sleep;
 };
 
 #if IS_ENABLED(CONFIG_PWM)