Merge tag 'pwm/for-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm

Pull pwm updates from Thierry Reding:
"Nothing too exciting for this cycle. A couple of fixes across the
board, and Lee volunteered to help with patch review"

* tag 'pwm/for-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm:
pwm: Add missing "CONFIG_" prefix
MAINTAINERS: Add Lee Jones as reviewer for the PWM subsystem
pwm: imx27: Fix rounding behavior
pwm: rockchip: Simplify rockchip_pwm_get_state()
pwm: img: Call pm_runtime_put() in pm_runtime_get_sync() failed case
pwm: tegra: Support dynamic clock frequency configuration
pwm: jz4740: Add support for the JZ4725B
pwm: jz4740: Make PWM start with the active part
pwm: jz4740: Enhance precision in calculation of duty cycle
pwm: jz4740: Drop dependency on MACH_INGENIC
pwm: lpss: Fix get_state runtime-pm reference handling
pwm: sun4i: Support direct clock output on Allwinner A64
pwm: Add support for Azoteq IQS620A PWM generator
dt-bindings: pwm: rcar: add r8a77961 support
pwm: Add missing '\n' in log messages

Documentation/devicetree/bindings/pwm/renesas,pwm-rcar.yaml

···
           - renesas,pwm-r8a7794   # R-Car E2
           - renesas,pwm-r8a7795   # R-Car H3
           - renesas,pwm-r8a7796   # R-Car M3-W
+          - renesas,pwm-r8a77961  # R-Car M3-W+
           - renesas,pwm-r8a77965  # R-Car M3-N
           - renesas,pwm-r8a77970  # R-Car V3M
           - renesas,pwm-r8a77980  # R-Car V3H

MAINTAINERS

···
 PWM SUBSYSTEM
 M:	Thierry Reding <[e-mail]>
 R:	Uwe Kleine-König <[e-mail]>
+M:	Lee Jones <[e-mail]>
 L:	[e-mail]
 S:	Maintained
 Q:	https://patchwork.ozlabs.org/project/linux-pwm/list/

drivers/pwm/Kconfig

···
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-imx-tpm.
 
+config PWM_IQS620A
+	tristate "Azoteq IQS620A PWM support"
+	depends on MFD_IQS62X || COMPILE_TEST
+	help
+	  Generic PWM framework driver for the Azoteq IQS620A multi-function
+	  sensor.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called pwm-iqs620a.
+
 config PWM_JZ4740
 	tristate "Ingenic JZ47xx PWM support"
-	depends on MACH_INGENIC
+	depends on MIPS
 	depends on COMMON_CLK
 	select MFD_SYSCON
 	help

drivers/pwm/Makefile

···
 obj-$(CONFIG_PWM_IMX1)		+= pwm-imx1.o
 obj-$(CONFIG_PWM_IMX27)		+= pwm-imx27.o
 obj-$(CONFIG_PWM_IMX_TPM)	+= pwm-imx-tpm.o
+obj-$(CONFIG_PWM_IQS620A)	+= pwm-iqs620a.o
 obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
 obj-$(CONFIG_PWM_LP3943)	+= pwm-lp3943.o
 obj-$(CONFIG_PWM_LPC18XX_SCT)	+= pwm-lpc18xx-sct.o

drivers/pwm/core.c

···
 		pwm->chip->ops->get_state(pwm->chip, pwm, &pwm->state);
 		trace_pwm_get(pwm, &pwm->state);
 
-		if (IS_ENABLED(PWM_DEBUG))
+		if (IS_ENABLED(CONFIG_PWM_DEBUG))
 			pwm->last = pwm->state;
 	}
 
···
 
 	if (!state->enabled && s2.enabled && s2.duty_cycle > 0)
 		dev_warn(chip->dev,
-			 "requested disabled, but yielded enabled with duty > 0");
+			 "requested disabled, but yielded enabled with duty > 0\n");
 
 	/* reapply the state that the driver reported being configured. */
 	err = chip->ops->apply(chip, pwm, &s1);

drivers/pwm/pwm-img.c

···
 	duty = DIV_ROUND_UP(timebase * duty_ns, period_ns);
 
 	ret = pm_runtime_get_sync(chip->dev);
-	if (ret < 0)
+	if (ret < 0) {
+		pm_runtime_put_autosuspend(chip->dev);
 		return ret;
+	}
 
 	val = img_pwm_readl(pwm_chip, PWM_CTRL_CFG);
 	val &= ~(PWM_CTRL_CFG_DIV_MASK << PWM_CTRL_CFG_DIV_SHIFT(pwm->hwpwm));
···
 	int ret;
 
 	ret = pm_runtime_get_sync(&pdev->dev);
-	if (ret < 0)
+	if (ret < 0) {
+		pm_runtime_put(&pdev->dev);
 		return ret;
+	}
 
 	for (i = 0; i < pwm_chip->chip.npwm; i++) {
 		val = img_pwm_readl(pwm_chip, PWM_CTRL_CFG);

drivers/pwm/pwm-imx27.c

···
 
 	prescaler = MX3_PWMCR_PRESCALER_GET(val);
 	pwm_clk = clk_get_rate(imx->clk_per);
-	pwm_clk = DIV_ROUND_CLOSEST_ULL(pwm_clk, prescaler);
 	val = readl(imx->mmio_base + MX3_PWMPR);
 	period = val >= MX3_PWMPR_MAX ? MX3_PWMPR_MAX : val;
 
 	/* PWMOUT (Hz) = PWMCLK / (PWMPR + 2) */
-	tmp = NSEC_PER_SEC * (u64)(period + 2);
-	state->period = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
+	tmp = NSEC_PER_SEC * (u64)(period + 2) * prescaler;
+	state->period = DIV_ROUND_UP_ULL(tmp, pwm_clk);
 
 	/*
 	 * PWMSAR can be read only if PWM is enabled. If the PWM is disabled,
···
 	else
 		val = imx->duty_cycle;
 
-	tmp = NSEC_PER_SEC * (u64)(val);
-	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
+	tmp = NSEC_PER_SEC * (u64)(val) * prescaler;
+	state->duty_cycle = DIV_ROUND_UP_ULL(tmp, pwm_clk);
 
 	pwm_imx27_clk_disable_unprepare(imx);
 }
···
 	struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
 	struct pwm_state cstate;
 	unsigned long long c;
+	unsigned long long clkrate;
 	int ret;
 	u32 cr;
 
 	pwm_get_state(pwm, &cstate);
 
-	c = clk_get_rate(imx->clk_per);
-	c *= state->period;
+	clkrate = clk_get_rate(imx->clk_per);
+	c = clkrate * state->period;
 
-	do_div(c, 1000000000);
+	do_div(c, NSEC_PER_SEC);
 	period_cycles = c;
 
 	prescale = period_cycles / 0x10000 + 1;
 
 	period_cycles /= prescale;
-	c = (unsigned long long)period_cycles * state->duty_cycle;
-	do_div(c, state->period);
+	c = clkrate * state->duty_cycle;
+	do_div(c, NSEC_PER_SEC * prescale);
 	duty_cycles = c;
 
 	/*

drivers/pwm/pwm-iqs620a.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Azoteq IQS620A PWM Generator
+ *
+ * Copyright (C) 2019 Jeff LaBundy <[e-mail]>
+ *
+ * Limitations:
+ * - The period is fixed to 1 ms and is generated continuously despite changes
+ *   to the duty cycle or enable/disable state.
+ * - Changes to the duty cycle or enable/disable state take effect immediately
+ *   and may result in a glitch during the period in which the change is made.
+ * - The device cannot generate a 0% duty cycle. For duty cycles below 1 / 256
+ *   ms, the output is disabled and relies upon an external pull-down resistor
+ *   to hold the GPIO3/LTX pin low.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/mfd/iqs62x.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define IQS620_PWR_SETTINGS			0xD2
+#define IQS620_PWR_SETTINGS_PWM_OUT		BIT(7)
+
+#define IQS620_PWM_DUTY_CYCLE			0xD8
+
+#define IQS620_PWM_PERIOD_NS			1000000
+
+struct iqs620_pwm_private {
+	struct iqs62x_core *iqs62x;
+	struct pwm_chip chip;
+	struct notifier_block notifier;
+	struct mutex lock;
+	bool out_en;
+	u8 duty_val;
+};
+
+static int iqs620_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	struct iqs620_pwm_private *iqs620_pwm;
+	struct iqs62x_core *iqs62x;
+	int duty_scale, ret;
+
+	if (state->polarity != PWM_POLARITY_NORMAL)
+		return -ENOTSUPP;
+
+	if (state->period < IQS620_PWM_PERIOD_NS)
+		return -EINVAL;
+
+	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
+	iqs62x = iqs620_pwm->iqs62x;
+
+	/*
+	 * The duty cycle generated by the device is calculated as follows:
+	 *
+	 * duty_cycle = (IQS620_PWM_DUTY_CYCLE + 1) / 256 * 1 ms
+	 *
+	 * ...where IQS620_PWM_DUTY_CYCLE is a register value between 0 and 255
+	 * (inclusive). Therefore the lowest duty cycle the device can generate
+	 * while the output is enabled is 1 / 256 ms.
+	 *
+	 * For lower duty cycles (e.g. 0), the PWM output is simply disabled to
+	 * allow an external pull-down resistor to hold the GPIO3/LTX pin low.
+	 */
+	duty_scale = state->duty_cycle * 256 / IQS620_PWM_PERIOD_NS;
+
+	mutex_lock(&iqs620_pwm->lock);
+
+	if (!state->enabled || !duty_scale) {
+		ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
+					 IQS620_PWR_SETTINGS_PWM_OUT, 0);
+		if (ret)
+			goto err_mutex;
+	}
+
+	if (duty_scale) {
+		u8 duty_val = min(duty_scale - 1, 0xFF);
+
+		ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
+				   duty_val);
+		if (ret)
+			goto err_mutex;
+
+		iqs620_pwm->duty_val = duty_val;
+	}
+
+	if (state->enabled && duty_scale) {
+		ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
+					 IQS620_PWR_SETTINGS_PWM_OUT, 0xFF);
+		if (ret)
+			goto err_mutex;
+	}
+
+	iqs620_pwm->out_en = state->enabled;
+
+err_mutex:
+	mutex_unlock(&iqs620_pwm->lock);
+
+	return ret;
+}
+
+static void iqs620_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+				 struct pwm_state *state)
+{
+	struct iqs620_pwm_private *iqs620_pwm;
+
+	iqs620_pwm = container_of(chip, struct iqs620_pwm_private, chip);
+
+	mutex_lock(&iqs620_pwm->lock);
+
+	/*
+	 * Since the device cannot generate a 0% duty cycle, requests to do so
+	 * cause subsequent calls to iqs620_pwm_get_state to report the output
+	 * as disabled with duty cycle equal to that which was in use prior to
+	 * the request. This is not ideal, but is the best compromise based on
+	 * the capabilities of the device.
+	 */
+	state->enabled = iqs620_pwm->out_en;
+	state->duty_cycle = DIV_ROUND_UP((iqs620_pwm->duty_val + 1) *
+					 IQS620_PWM_PERIOD_NS, 256);
+
+	mutex_unlock(&iqs620_pwm->lock);
+
+	state->period = IQS620_PWM_PERIOD_NS;
+}
+
+static int iqs620_pwm_notifier(struct notifier_block *notifier,
+			       unsigned long event_flags, void *context)
+{
+	struct iqs620_pwm_private *iqs620_pwm;
+	struct iqs62x_core *iqs62x;
+	int ret;
+
+	if (!(event_flags & BIT(IQS62X_EVENT_SYS_RESET)))
+		return NOTIFY_DONE;
+
+	iqs620_pwm = container_of(notifier, struct iqs620_pwm_private,
+				  notifier);
+	iqs62x = iqs620_pwm->iqs62x;
+
+	mutex_lock(&iqs620_pwm->lock);
+
+	/*
+	 * The parent MFD driver already prints an error message in the event
+	 * of a device reset, so nothing else is printed here unless there is
+	 * an additional failure.
+	 */
+	ret = regmap_write(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE,
+			   iqs620_pwm->duty_val);
+	if (ret)
+		goto err_mutex;
+
+	ret = regmap_update_bits(iqs62x->regmap, IQS620_PWR_SETTINGS,
+				 IQS620_PWR_SETTINGS_PWM_OUT,
+				 iqs620_pwm->out_en ? 0xFF : 0);
+
+err_mutex:
+	mutex_unlock(&iqs620_pwm->lock);
+
+	if (ret) {
+		dev_err(iqs620_pwm->chip.dev,
+			"Failed to re-initialize device: %d\n", ret);
+		return NOTIFY_BAD;
+	}
+
+	return NOTIFY_OK;
+}
+
+static const struct pwm_ops iqs620_pwm_ops = {
+	.apply = iqs620_pwm_apply,
+	.get_state = iqs620_pwm_get_state,
+	.owner = THIS_MODULE,
+};
+
+static void iqs620_pwm_notifier_unregister(void *context)
+{
+	struct iqs620_pwm_private *iqs620_pwm = context;
+	int ret;
+
+	ret = blocking_notifier_chain_unregister(&iqs620_pwm->iqs62x->nh,
+						 &iqs620_pwm->notifier);
+	if (ret)
+		dev_err(iqs620_pwm->chip.dev,
+			"Failed to unregister notifier: %d\n", ret);
+}
+
+static int iqs620_pwm_probe(struct platform_device *pdev)
+{
+	struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
+	struct iqs620_pwm_private *iqs620_pwm;
+	unsigned int val;
+	int ret;
+
+	iqs620_pwm = devm_kzalloc(&pdev->dev, sizeof(*iqs620_pwm), GFP_KERNEL);
+	if (!iqs620_pwm)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, iqs620_pwm);
+	iqs620_pwm->iqs62x = iqs62x;
+
+	ret = regmap_read(iqs62x->regmap, IQS620_PWR_SETTINGS, &val);
+	if (ret)
+		return ret;
+	iqs620_pwm->out_en = val & IQS620_PWR_SETTINGS_PWM_OUT;
+
+	ret = regmap_read(iqs62x->regmap, IQS620_PWM_DUTY_CYCLE, &val);
+	if (ret)
+		return ret;
+	iqs620_pwm->duty_val = val;
+
+	iqs620_pwm->chip.dev = &pdev->dev;
+	iqs620_pwm->chip.ops = &iqs620_pwm_ops;
+	iqs620_pwm->chip.base = -1;
+	iqs620_pwm->chip.npwm = 1;
+
+	mutex_init(&iqs620_pwm->lock);
+
+	iqs620_pwm->notifier.notifier_call = iqs620_pwm_notifier;
+	ret = blocking_notifier_chain_register(&iqs620_pwm->iqs62x->nh,
+					       &iqs620_pwm->notifier);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(&pdev->dev,
+				       iqs620_pwm_notifier_unregister,
+				       iqs620_pwm);
+	if (ret)
+		return ret;
+
+	ret = pwmchip_add(&iqs620_pwm->chip);
+	if (ret)
+		dev_err(&pdev->dev, "Failed to add device: %d\n", ret);
+
+	return ret;
+}
+
+static int iqs620_pwm_remove(struct platform_device *pdev)
+{
+	struct iqs620_pwm_private *iqs620_pwm = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = pwmchip_remove(&iqs620_pwm->chip);
+	if (ret)
+		dev_err(&pdev->dev, "Failed to remove device: %d\n", ret);
+
+	return ret;
+}
+
+static struct platform_driver iqs620_pwm_platform_driver = {
+	.driver = {
+		.name = "iqs620a-pwm",
+	},
+	.probe = iqs620_pwm_probe,
+	.remove = iqs620_pwm_remove,
+};
+module_platform_driver(iqs620_pwm_platform_driver);
+
+MODULE_AUTHOR("Jeff LaBundy <[e-mail]>");
+MODULE_DESCRIPTION("Azoteq IQS620A PWM Generator");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:iqs620a-pwm");

drivers/pwm/pwm-jz4740.c

···
  * Limitations:
  * - The .apply callback doesn't complete the currently running period before
  *   reconfiguring the hardware.
- * - Each period starts with the inactive part.
  */
 
 #include <linux/clk.h>
···
 #include <linux/pwm.h>
 #include <linux/regmap.h>
 
-#define NUM_PWM 8
+struct soc_info {
+	unsigned int num_pwms;
+};
 
 struct jz4740_pwm_chip {
 	struct pwm_chip chip;
···
 				   unsigned int channel)
 {
 	/* Enable all TCU channels for PWM use by default except channels 0/1 */
-	u32 pwm_channels_mask = GENMASK(NUM_PWM - 1, 2);
+	u32 pwm_channels_mask = GENMASK(jz->chip.npwm - 1, 2);
 
 	device_property_read_u32(jz->chip.dev->parent,
 				 "ingenic,pwm-channels-mask",
···
 	/* Calculate period value */
 	tmp = (unsigned long long)rate * state->period;
 	do_div(tmp, NSEC_PER_SEC);
-	period = (unsigned long)tmp;
+	period = tmp;
 
 	/* Calculate duty value */
-	tmp = (unsigned long long)period * state->duty_cycle;
-	do_div(tmp, state->period);
-	duty = period - tmp;
+	tmp = (unsigned long long)rate * state->duty_cycle;
+	do_div(tmp, NSEC_PER_SEC);
+	duty = tmp;
 
 	if (duty >= period)
 		duty = period - 1;
···
 	regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
 			   TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD);
 
-	/* Set polarity */
-	switch (state->polarity) {
-	case PWM_POLARITY_NORMAL:
+	/*
+	 * Set polarity.
+	 *
+	 * The PWM starts in inactive state until the internal timer reaches the
+	 * duty value, then becomes active until the timer reaches the period
+	 * value. In theory, we should then use (period - duty) as the real duty
+	 * value, as a high duty value would otherwise result in the PWM pin
+	 * being inactive most of the time.
+	 *
+	 * Here, we don't do that, and instead invert the polarity of the PWM
+	 * when it is active. This trick makes the PWM start with its active
+	 * state instead of its inactive state.
+	 */
+	if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
 		regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
 				   TCU_TCSR_PWM_INITL_HIGH, 0);
-		break;
-	case PWM_POLARITY_INVERSED:
+	else
 		regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
 				   TCU_TCSR_PWM_INITL_HIGH,
 				   TCU_TCSR_PWM_INITL_HIGH);
-		break;
-	}
 
 	if (state->enabled)
 		jz4740_pwm_enable(chip, pwm);
···
 {
 	struct device *dev = &pdev->dev;
 	struct jz4740_pwm_chip *jz4740;
+	const struct soc_info *info;
+
+	info = device_get_match_data(dev);
+	if (!info)
+		return -EINVAL;
 
 	jz4740 = devm_kzalloc(dev, sizeof(*jz4740), GFP_KERNEL);
 	if (!jz4740)
···
 
 	jz4740->chip.dev = dev;
 	jz4740->chip.ops = &jz4740_pwm_ops;
-	jz4740->chip.npwm = NUM_PWM;
+	jz4740->chip.npwm = info->num_pwms;
 	jz4740->chip.base = -1;
 	jz4740->chip.of_xlate = of_pwm_xlate_with_flags;
 	jz4740->chip.of_pwm_n_cells = 3;
···
 	return pwmchip_remove(&jz4740->chip);
 }
 
+static const struct soc_info __maybe_unused jz4740_soc_info = {
+	.num_pwms = 8,
+};
+
+static const struct soc_info __maybe_unused jz4725b_soc_info = {
+	.num_pwms = 6,
+};
+
 #ifdef CONFIG_OF
 static const struct of_device_id jz4740_pwm_dt_ids[] = {
-	{ .compatible = "ingenic,jz4740-pwm", },
+	{ .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info },
+	{ .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info },
 	{},
 };
 MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);

drivers/pwm/pwm-lpss.c

···
 	return 0;
 }
 
-/* This function gets called once from pwmchip_add to get the initial state */
 static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 			       struct pwm_state *state)
 {
···
 	unsigned long base_unit_range;
 	unsigned long long base_unit, freq, on_time_div;
 	u32 ctrl;
+
+	pm_runtime_get_sync(chip->dev);
 
 	base_unit_range = BIT(lpwm->info->base_unit_bits);
 
···
 	state->polarity = PWM_POLARITY_NORMAL;
 	state->enabled = !!(ctrl & PWM_ENABLE);
 
-	if (state->enabled)
-		pm_runtime_get(chip->dev);
+	pm_runtime_put(chip->dev);
 }
 
 static const struct pwm_ops pwm_lpss_ops = {
···
 {
 	struct pwm_lpss_chip *lpwm;
 	unsigned long c;
-	int ret;
+	int i, ret;
+	u32 ctrl;
 
 	if (WARN_ON(info->npwm > MAX_PWMS))
 		return ERR_PTR(-ENODEV);
···
 	if (ret) {
 		dev_err(dev, "failed to add PWM chip: %d\n", ret);
 		return ERR_PTR(ret);
+	}
+
+	for (i = 0; i < lpwm->info->npwm; i++) {
+		ctrl = pwm_lpss_read(&lpwm->chip.pwms[i]);
+		if (ctrl & PWM_ENABLE)
+			pm_runtime_get(dev);
 	}
 
 	return lpwm;

drivers/pwm/pwm-rockchip.c

···
 	state->duty_cycle =  DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
 
 	val = readl_relaxed(pc->base + pc->data->regs.ctrl);
-	if (pc->data->supports_polarity)
-		state->enabled = ((val & enable_conf) != enable_conf) ?
-				 false : true;
-	else
-		state->enabled = ((val & enable_conf) == enable_conf) ?
-				 true : false;
+	state->enabled = (val & enable_conf) == enable_conf;
 
 	if (pc->data->supports_polarity && !(val & PWM_DUTY_POSITIVE))
 		state->polarity = PWM_POLARITY_INVERSED;

drivers/pwm/pwm-sun4i.c

···
 	.npwm = 1,
 };
 
+static const struct sun4i_pwm_data sun50i_a64_pwm_data = {
+	.has_prescaler_bypass = true,
+	.has_direct_mod_clk_output = true,
+	.npwm = 1,
+};
+
 static const struct sun4i_pwm_data sun50i_h6_pwm_data = {
 	.has_prescaler_bypass = true,
 	.has_direct_mod_clk_output = true,
···
 	}, {
 		.compatible = "allwinner,sun8i-h3-pwm",
 		.data = &sun4i_pwm_single_bypass,
+	}, {
+		.compatible = "allwinner,sun50i-a64-pwm",
+		.data = &sun50i_a64_pwm_data,
 	}, {
 		.compatible = "allwinner,sun50i-h6-pwm",
 		.data = &sun50i_h6_pwm_data,

drivers/pwm/pwm-tegra.c

···
  *
  * Tegra pulse-width-modulation controller driver
  *
- * Copyright (c) 2010, NVIDIA Corporation.
+ * Copyright (c) 2010-2020, NVIDIA Corporation.
  * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <[e-mail]>
+ *
+ * Overview of Tegra Pulse Width Modulator Register:
+ * 1. 13-bit: Frequency division (SCALE)
+ * 2. 8-bit : Pulse division (DUTY)
+ * 3. 1-bit : Enable bit
+ *
+ * The PWM clock frequency is divided by 256 before subdividing it based
+ * on the programmable frequency division value to generate the required
+ * frequency for PWM output. The maximum output frequency that can be
+ * achieved is (max rate of source clock) / 256.
+ * e.g. if source clock rate is 408 MHz, maximum output frequency can be:
+ * 408 MHz/256 = 1.6 MHz.
+ * This 1.6 MHz frequency can further be divided using SCALE value in PWM.
+ *
+ * PWM pulse width: 8 bits are usable [23:16] for varying pulse width.
+ * To achieve 100% duty cycle, program Bit [24] of this register to
+ * 1’b1. In which case the other bits [23:16] are set to don't care.
+ *
+ * Limitations:
+ * -	When PWM is disabled, the output is driven to inactive.
+ * -	It does not allow the current PWM period to complete and
+ *	stops abruptly.
+ *
+ * -	If the register is reconfigured while PWM is running,
+ *	it does not complete the currently running period.
+ *
+ * -	If the user input duty is beyond acceptible limits,
+ *	-EINVAL is returned.
  */
 
 #include <linux/clk.h>
···
 	struct reset_control*rst;
 
 	unsigned long clk_rate;
+	unsigned long min_period_ns;
 
 	void __iomem *regs;
 
···
 {
 	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
 	unsigned long long c = duty_ns, hz;
-	unsigned long rate;
+	unsigned long rate, required_clk_rate;
 	u32 val = 0;
 	int err;
 
···
 	val = (u32)c << PWM_DUTY_SHIFT;
 
 	/*
+	 *  min period = max clock limit >> PWM_DUTY_WIDTH
+	 */
+	if (period_ns < pc->min_period_ns)
+		return -EINVAL;
+
+	/*
 	 * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
 	 * cycles at the PWM clock rate will take period_ns nanoseconds.
+	 *
+	 * num_channels: If single instance of PWM controller has multiple
+	 * channels (e.g. Tegra210 or older) then it is not possible to
+	 * configure separate clock rates to each of the channels, in such
+	 * case the value stored during probe will be referred.
+	 *
+	 * If every PWM controller instance has one channel respectively, i.e.
+	 * nums_channels == 1 then only the clock rate can be modified
+	 * dynamically (e.g. Tegra186 or Tegra194).
 	 */
+	if (pc->soc->num_channels == 1) {
+		/*
+		 * Rate is multiplied with 2^PWM_DUTY_WIDTH so that it matches
+		 * with the maximum possible rate that the controller can
+		 * provide. Any further lower value can be derived by setting
+		 * PFM bits[0:12].
+		 *
+		 * required_clk_rate is a reference rate for source clock and
+		 * it is derived based on user requested period. By setting the
+		 * source clock rate as required_clk_rate, PWM controller will
+		 * be able to configure the requested period.
+		 */
+		required_clk_rate =
+			(NSEC_PER_SEC / period_ns) << PWM_DUTY_WIDTH;
+
+		err = clk_set_rate(pc->clk, required_clk_rate);
+		if (err < 0)
+			return -EINVAL;
+
+		/* Store the new rate for further references */
+		pc->clk_rate = clk_get_rate(pc->clk);
+	}
+
 	rate = pc->clk_rate >> PWM_DUTY_WIDTH;
 
 	/* Consider precision in PWM_SCALE_WIDTH rate calculation */
···
 
 	/*
 	 * Since the actual PWM divider is the register's frequency divider
-	 * field minus 1, we need to decrement to get the correct value to
+	 * field plus 1, we need to decrement to get the correct value to
 	 * write to the register.
 	 */
 	if (rate > 0)
···
 	 */
 	pwm->clk_rate = clk_get_rate(pwm->clk);
 
+	/* Set minimum limit of PWM period for the IP */
+	pwm->min_period_ns =
+	    (NSEC_PER_SEC / (pwm->soc->max_frequency >> PWM_DUTY_WIDTH)) + 1;
+
 	pwm->rst = devm_reset_control_get_exclusive(&pdev->dev, "pwm");
 	if (IS_ERR(pwm->rst)) {
 		ret = PTR_ERR(pwm->rst);
···
 module_platform_driver(tegra_pwm_driver);
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("NVIDIA Corporation");
+MODULE_AUTHOR("Sandipan Patra <[e-mail]>");
+MODULE_DESCRIPTION("Tegra PWM controller driver");
 MODULE_ALIAS("platform:tegra-pwm");