[PATCH v15] pwm: opencores: Add PWM driver support

[PATCH v15] pwm: opencores: Add PWM driver support

[William Qiu]

Add driver for OpenCores PWM Controller. And add compatibility code
which based on StarFive SoC.

Co-developed-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: Hal Feng <hal.feng@starfivetech.com>
Signed-off-by: William Qiu <william.qiu@starfivetech.com>
---
 MAINTAINERS              |   7 ++
 drivers/pwm/Kconfig      |  12 ++
 drivers/pwm/Makefile     |   1 +
 drivers/pwm/pwm-ocores.c | 241 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 261 insertions(+)
 create mode 100644 drivers/pwm/pwm-ocores.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 10430778c998..f0475a3b8683 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17148,6 +17148,13 @@ F:	Documentation/i2c/busses/i2c-ocores.rst
 F:	drivers/i2c/busses/i2c-ocores.c
 F:	include/linux/platform_data/i2c-ocores.h
 
+OPENCORES PWM DRIVER
+M:	William Qiu <william.qiu@starfivetech.com>
+M:	Hal Feng <hal.feng@starfivetech.com>
+S:	Supported
+F:	Documentation/devicetree/bindings/pwm/opencores,pwm.yaml
+F:	drivers/pwm/pwm-ocores.c
+
 OPENRISC ARCHITECTURE
 M:	Jonas Bonn <jonas@southpole.se>
 M:	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 3e53838990f5..7682936484aa 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -464,6 +464,18 @@ config PWM_NTXEC
 	  controller found in certain e-book readers designed by the original
 	  design manufacturer Netronix.
 
+config PWM_OCORES
+	tristate "OpenCores PTC PWM support"
+	depends on HAS_IOMEM && OF
+	depends on COMMON_CLK
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	help
+	  If you say yes to this option, support will be included for the
+	  OpenCores PWM. For details see https://opencores.org/projects/ptc.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-ocores.
+
 config PWM_OMAP_DMTIMER
 	tristate "OMAP Dual-Mode Timer PWM support"
 	depends on OF
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 0be4f3e6dd43..5d87811e8537 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
 obj-$(CONFIG_PWM_MTK_DISP)	+= pwm-mtk-disp.o
 obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
 obj-$(CONFIG_PWM_NTXEC)		+= pwm-ntxec.o
+obj-$(CONFIG_PWM_OCORES)	+= pwm-ocores.o
 obj-$(CONFIG_PWM_OMAP_DMTIMER)	+= pwm-omap-dmtimer.o
 obj-$(CONFIG_PWM_PCA9685)	+= pwm-pca9685.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
diff --git a/drivers/pwm/pwm-ocores.c b/drivers/pwm/pwm-ocores.c
new file mode 100644
index 000000000000..d0161b9379d1
--- /dev/null
+++ b/drivers/pwm/pwm-ocores.c
@@ -0,0 +1,241 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OpenCores PWM Driver
+ *
+ * https://opencores.org/projects/ptc
+ *
+ * Copyright (C) 2018-2023 StarFive Technology Co., Ltd.
+ *
+ * Limitations:
+ * - The hardware only supports inverted polarity.
+ * - The hardware minimum period / duty_cycle is (1 / pwm_apb clock frequency).
+ * - The hardware maximum period / duty_cycle is (U32_MAX / pwm_apb clock frequency).
+ * - The output is set to a low level immediately when disabled.
+ * - When configuration changes are done, they get active immediately without resetting
+ *   the counter. This might result in one period affected by both old and new settings.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+
+/* OpenCores Register offsets */
+#define REG_OCPWM_CNTR    0x0
+#define REG_OCPWM_HRC     0x4
+#define REG_OCPWM_LRC     0x8
+#define REG_OCPWM_CTRL    0xC
+
+/* OCPWM_CTRL register bits*/
+#define REG_OCPWM_CNTR_EN      BIT(0)
+#define REG_OCPWM_CNTR_ECLK    BIT(1)
+#define REG_OCPWM_CNTR_NEC     BIT(2)
+#define REG_OCPWM_CNTR_OE      BIT(3)
+#define REG_OCPWM_CNTR_SIGNLE  BIT(4)
+#define REG_OCPWM_CNTR_INTE    BIT(5)
+#define REG_OCPWM_CNTR_INT     BIT(6)
+#define REG_OCPWM_CNTR_RST     BIT(7)
+#define REG_OCPWM_CNTR_CAPTE   BIT(8)
+
+struct ocores_pwm_data {
+	void __iomem *(*get_ch_base)(void __iomem *base, unsigned int channel);
+};
+
+struct ocores_pwm_device {
+	const struct ocores_pwm_data *data;
+	void __iomem *regs;
+	u32 clk_rate; /* PWM APB clock frequency */
+};
+
+static inline u32 ocores_pwm_readl(struct ocores_pwm_device *ddata,
+				   unsigned int channel,
+				   unsigned int offset)
+{
+	void __iomem *base = ddata->data->get_ch_base ?
+			     ddata->data->get_ch_base(ddata->regs, channel) : ddata->regs;
+
+	return readl(base + offset);
+}
+
+static inline void ocores_pwm_writel(struct ocores_pwm_device *ddata,
+				     unsigned int channel,
+				     unsigned int offset, u32 val)
+{
+	void __iomem *base = ddata->data->get_ch_base ?
+			     ddata->data->get_ch_base(ddata->regs, channel) : ddata->regs;
+
+	writel(val, base + offset);
+}
+
+static inline struct ocores_pwm_device *chip_to_ocores(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
+
+static void __iomem *starfive_get_ch_base(void __iomem *base,
+					  unsigned int channel)
+{
+	unsigned int offset = (channel & 4) << 13 | (channel & 3) << 4;
+
+	return base + offset;
+}
+
+static int ocores_pwm_get_state(struct pwm_chip *chip,
+				struct pwm_device *pwm,
+				struct pwm_state *state)
+{
+	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
+	u32 period_data, duty_data, ctrl_data;
+
+	period_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_LRC);
+	duty_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_HRC);
+	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
+
+	state->period = DIV_ROUND_UP_ULL((u64)period_data * NSEC_PER_SEC, ddata->clk_rate);
+	state->duty_cycle = DIV_ROUND_UP_ULL((u64)duty_data * NSEC_PER_SEC, ddata->clk_rate);
+	state->polarity = PWM_POLARITY_INVERSED;
+	state->enabled = (ctrl_data & REG_OCPWM_CNTR_EN) ? true : false;
+
+	return 0;
+}
+
+static int ocores_pwm_apply(struct pwm_chip *chip,
+			    struct pwm_device *pwm,
+			    const struct pwm_state *state)
+{
+	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
+	u32 ctrl_data = 0;
+	u64 period_data, duty_data;
+
+	if (state->polarity != PWM_POLARITY_INVERSED)
+		return -EINVAL;
+
+	period_data = mul_u64_u32_div(state->period, ddata->clk_rate, NSEC_PER_SEC);
+	if (!period_data)
+		return -EINVAL;
+
+	if (period_data > U32_MAX)
+		period_data = U32_MAX;
+
+	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_LRC, (u32)period_data);
+
+	duty_data = mul_u64_u32_div(state->duty_cycle, ddata->clk_rate, NSEC_PER_SEC);
+	if (!duty_data)
+		return -EINVAL;
+
+	if (duty_data > U32_MAX)
+		duty_data = U32_MAX;
+
+	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC, (u32)duty_data);
+
+	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
+	if (state->enabled)
+		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
+				  ctrl_data | REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE);
+	else
+		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
+				  ctrl_data & ~(REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE));
+
+	return 0;
+}
+
+static const struct pwm_ops ocores_pwm_ops = {
+	.get_state = ocores_pwm_get_state,
+	.apply = ocores_pwm_apply,
+};
+
+static const struct ocores_pwm_data starfive_pwm_data = {
+	.get_ch_base = starfive_get_ch_base,
+};
+
+static const struct of_device_id ocores_pwm_of_match[] = {
+	{ .compatible = "opencores,pwm-v1" },
+	{ .compatible = "starfive,jh7100-pwm", .data = &starfive_pwm_data},
+	{ .compatible = "starfive,jh7110-pwm", .data = &starfive_pwm_data},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ocores_pwm_of_match);
+
+static void ocores_pwm_reset_control_assert(void *data)
+{
+	reset_control_assert(data);
+}
+
+static int ocores_pwm_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *id;
+	struct device *dev = &pdev->dev;
+	struct ocores_pwm_device *ddata;
+	struct pwm_chip *chip;
+	struct clk *clk;
+	struct reset_control *rst;
+	int ret;
+
+	id = of_match_device(ocores_pwm_of_match, dev);
+	if (!id)
+		return -EINVAL;
+
+	chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*ddata));
+	if (IS_ERR(chip))
+		return -ENOMEM;
+
+	ddata = chip_to_ocores(chip);
+	ddata->data = id->data;
+	chip->ops = &ocores_pwm_ops;
+
+	ddata->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ddata->regs))
+		return dev_err_probe(dev, PTR_ERR(ddata->regs),
+				     "Unable to map IO resources\n");
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk),
+				     "Unable to get pwm's clock\n");
+
+	ret = devm_clk_rate_exclusive_get(dev, clk);
+	if (ret)
+		return ret;
+
+	rst = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(dev, PTR_ERR(rst),
+				     "Unable to get pwm's reset\n");
+
+	ret = reset_control_deassert(rst);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, ocores_pwm_reset_control_assert, rst);
+	if (ret)
+		return ret;
+
+	ddata->clk_rate = clk_get_rate(clk);
+	if (ddata->clk_rate > NSEC_PER_SEC)
+		return -EINVAL;
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
+
+	return 0;
+}
+
+static struct platform_driver ocores_pwm_driver = {
+	.probe = ocores_pwm_probe,
+	.driver = {
+		.name = "ocores-pwm",
+		.of_match_table = ocores_pwm_of_match,
+	},
+};
+module_platform_driver(ocores_pwm_driver);
+
+MODULE_AUTHOR("Jieqin Chen");
+MODULE_AUTHOR("Hal Feng <hal.feng@starfivetech.com>");
+MODULE_DESCRIPTION("OpenCores PTC PWM driver");
+MODULE_LICENSE("GPL");
-- 
2.34.1

Re: [PATCH v15] pwm: opencores: Add PWM driver support

[Uwe Kleine-König]

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Hello William,

On Sat, Sep 14, 2024 at 05:51:14PM +0800, William Qiu wrote:
> diff --git a/drivers/pwm/pwm-ocores.c b/drivers/pwm/pwm-ocores.c
> new file mode 100644
> index 000000000000..d0161b9379d1
> --- /dev/null
> +++ b/drivers/pwm/pwm-ocores.c
> @@ -0,0 +1,241 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * OpenCores PWM Driver
> + *
> + * https://opencores.org/projects/ptc
> + *
> + * Copyright (C) 2018-2023 StarFive Technology Co., Ltd.
> + *
> + * Limitations:
> + * - The hardware only supports inverted polarity.
> + * - The hardware minimum period / duty_cycle is (1 / pwm_apb clock frequency).
> + * - The hardware maximum period / duty_cycle is (U32_MAX / pwm_apb clock frequency).
> + * - The output is set to a low level immediately when disabled.

Huh, that's a 100% relative duty cycle. But fine, that gives the
opportunity to find bugs in consumer drivers. :-)

> + * - When configuration changes are done, they get active immediately without resetting
> + *   the counter. This might result in one period affected by both old and new settings.
> + */
> +
> [...]
> +static inline void ocores_pwm_writel(struct ocores_pwm_device *ddata,
> +				     unsigned int channel,
> +				     unsigned int offset, u32 val)
> [...]
> +static inline struct ocores_pwm_device *chip_to_ocores(struct pwm_chip *chip)
> [...]
> +static void __iomem *starfive_get_ch_base(void __iomem *base,
> +					  unsigned int channel)

Would be great if all functions had the same prefix. This simplifies
debugging with tracing, because you can just enable traces for
"ocores_pwm_*".

> [...]
> +static int ocores_pwm_apply(struct pwm_chip *chip,
> +			    struct pwm_device *pwm,
> +			    const struct pwm_state *state)
> +{
> +	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
> +	u32 ctrl_data = 0;
> +	u64 period_data, duty_data;
> +
> +	if (state->polarity != PWM_POLARITY_INVERSED)
> +		return -EINVAL;
> +
> +	period_data = mul_u64_u32_div(state->period, ddata->clk_rate, NSEC_PER_SEC);
> +	if (!period_data)
> +		return -EINVAL;
> +
> +	if (period_data > U32_MAX)
> +		period_data = U32_MAX;
> +
> +	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_LRC, (u32)period_data);

The cast isn't needed.

> +	duty_data = mul_u64_u32_div(state->duty_cycle, ddata->clk_rate, NSEC_PER_SEC);
> +	if (!duty_data)
> +		return -EINVAL;
> +
> +	if (duty_data > U32_MAX)
> +		duty_data = U32_MAX;
> +
> +	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC, (u32)duty_data);

ditto.

> +	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
> +	if (state->enabled)
> +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> +				  ctrl_data | REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE);
> +	else
> +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> +				  ctrl_data & ~(REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE));

If you're clearing REG_OCPWM_CNTR_OE (Output Enable?), does the output
really go low? Or is that due to an external pull down on your board?

> +
> +	return 0;
> +}
> [...]
> +static int ocores_pwm_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *id;
> +	struct device *dev = &pdev->dev;
> +	struct ocores_pwm_device *ddata;
> +	struct pwm_chip *chip;
> +	struct clk *clk;
> +	struct reset_control *rst;
> +	int ret;
> +
> +	id = of_match_device(ocores_pwm_of_match, dev);
> +	if (!id)
> +		return -EINVAL;

Error message here? Better use device_get_match_data() here. Then you
don't need the of-specific headers (IIUC).

> +	chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*ddata));
> +	if (IS_ERR(chip))
> +		return -ENOMEM;
> +
> +	ddata = chip_to_ocores(chip);
> +	ddata->data = id->data;
> +	chip->ops = &ocores_pwm_ops;
> +
> +	ddata->regs = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(ddata->regs))
> +		return dev_err_probe(dev, PTR_ERR(ddata->regs),
> +				     "Unable to map IO resources\n");
> +
> +	clk = devm_clk_get_enabled(dev, NULL);
> +	if (IS_ERR(clk))
> +		return dev_err_probe(dev, PTR_ERR(clk),
> +				     "Unable to get pwm's clock\n");
> +
> +	ret = devm_clk_rate_exclusive_get(dev, clk);
> +	if (ret)
> +		return ret;
> +
> +	rst = devm_reset_control_get_optional_exclusive(dev, NULL);
> +	if (IS_ERR(rst))
> +		return dev_err_probe(dev, PTR_ERR(rst),
> +				     "Unable to get pwm's reset\n");
> +
> +	ret = reset_control_deassert(rst);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_add_action_or_reset(dev, ocores_pwm_reset_control_assert, rst);
> +	if (ret)
> +		return ret;

If you respin anyhow, switch to
devm_reset_control_get_optional_exclusive_deasserted(). Up to now this
only exists in next, but I'd care to apply this is a way that doesn't
fail to build then.

> +	ddata->clk_rate = clk_get_rate(clk);
> +	if (ddata->clk_rate > NSEC_PER_SEC)
> +		return -EINVAL;
> +
> +	ret = devm_pwmchip_add(dev, chip);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
> +
> +	return 0;
> +}

Best regards
Uwe

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Re: [PATCH v15] pwm: opencores: Add PWM driver support

[Uwe Kleine-König]

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On Sat, Oct 12, 2024 at 08:02:57AM +0000, William Qiu wrote:
> 
> 
> > -----Original Message-----
> > From: William Qiu
> > Sent: 2024年10月11日 18:43
> > To: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> > Cc: linux-kernel@vger.kernel.org; linux-pwm@vger.kernel.org; Hal Feng
> > <hal.feng@starfivetech.com>; Philipp Zabel <p.zabel@pengutronix.de>
> > Subject: RE: [PATCH v15] pwm: opencores: Add PWM driver support
> > 
> > > +static void __iomem *starfive_get_ch_base(void __iomem *base,
> > +					  unsigned int channel)
> > >
> > > Would be great if all functions had the same prefix. This simplifies
> > > debugging with tracing, because you can just enable traces for
> > "ocores_pwm_*".
> > >
> > Will update.
> 
> I want to explain something about this. This interface only works on
> StarFive boards, so the "starfive" prefix is used, I don't think the
> "ocores_pwm" prefix is appropriate here.
> 
> Uwe, what do you think?

This function is part of the opencores pwm driver, so ocores_pwm_ is an
appropriate prefix.

Best regards
Uwe

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RE: [PATCH v15] pwm: opencores: Add PWM driver support

[William Qiu]

> -----Original Message-----
> From: William Qiu
> Sent: 2024年10月11日 18:43
> To: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> Cc: linux-kernel@vger.kernel.org; linux-pwm@vger.kernel.org; Hal Feng
> <hal.feng@starfivetech.com>; Philipp Zabel <p.zabel@pengutronix.de>
> Subject: RE: [PATCH v15] pwm: opencores: Add PWM driver support
> 
> > +static void __iomem *starfive_get_ch_base(void __iomem *base,
> +					  unsigned int channel)
> >
> > Would be great if all functions had the same prefix. This simplifies
> > debugging with tracing, because you can just enable traces for
> "ocores_pwm_*".
> >
> Will update.

I want to explain something about this. This interface only works on
StarFive boards, so the "starfive" prefix is used, I don't think the
"ocores_pwm" prefix is appropriate here.

Uwe, what do you think?

Best Regards,
William

RE: [PATCH v15] pwm: opencores: Add PWM driver support

[William Qiu]

> -----Original Message-----
> From: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> Sent: 2024年10月9日 16:11
> To: William Qiu <william.qiu@starfivetech.com>
> Cc: linux-kernel@vger.kernel.org; linux-pwm@vger.kernel.org; Hal Feng
> <hal.feng@starfivetech.com>; Philipp Zabel <p.zabel@pengutronix.de>
> Subject: Re: [PATCH v15] pwm: opencores: Add PWM driver support
> 
> Hello William,
> 
> On Sat, Sep 14, 2024 at 05:51:14PM +0800, William Qiu wrote:
> > diff --git a/drivers/pwm/pwm-ocores.c b/drivers/pwm/pwm-ocores.c new
> > file mode 100644 index 000000000000..d0161b9379d1
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-ocores.c
> > @@ -0,0 +1,241 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * OpenCores PWM Driver
> > + *
> > + * https://opencores.org/projects/ptc
> > + *
> > + * Copyright (C) 2018-2023 StarFive Technology Co., Ltd.
> > + *
> > + * Limitations:
> > + * - The hardware only supports inverted polarity.
> > + * - The hardware minimum period / duty_cycle is (1 / pwm_apb clock
> frequency).
> > + * - The hardware maximum period / duty_cycle is (U32_MAX / pwm_apb
> clock frequency).
> > + * - The output is set to a low level immediately when disabled.
> 
> Huh, that's a 100% relative duty cycle. But fine, that gives the opportunity to
> find bugs in consumer drivers. :-)
> 
> > + * - When configuration changes are done, they get active immediately
> without resetting
> > + *   the counter. This might result in one period affected by both old and
> new settings.
> > + */
> > +
> > [...]
> > +static inline void ocores_pwm_writel(struct ocores_pwm_device *ddata,
> > +				     unsigned int channel,
> > +				     unsigned int offset, u32 val)
> > [...]
> > +static inline struct ocores_pwm_device *chip_to_ocores(struct
> > +pwm_chip *chip)
> > [...]
> > +static void __iomem *starfive_get_ch_base(void __iomem *base,
> > +					  unsigned int channel)
> 
> Would be great if all functions had the same prefix. This simplifies debugging
> with tracing, because you can just enable traces for "ocores_pwm_*".
> 
Will update.
> > [...]
> > +static int ocores_pwm_apply(struct pwm_chip *chip,
> > +			    struct pwm_device *pwm,
> > +			    const struct pwm_state *state) {
> > +	struct ocores_pwm_device *ddata = chip_to_ocores(chip);
> > +	u32 ctrl_data = 0;
> > +	u64 period_data, duty_data;
> > +
> > +	if (state->polarity != PWM_POLARITY_INVERSED)
> > +		return -EINVAL;
> > +
> > +	period_data = mul_u64_u32_div(state->period, ddata->clk_rate,
> NSEC_PER_SEC);
> > +	if (!period_data)
> > +		return -EINVAL;
> > +
> > +	if (period_data > U32_MAX)
> > +		period_data = U32_MAX;
> > +
> > +	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_LRC,
> > +(u32)period_data);
> 
> The cast isn't needed.
> 
Will drop
> > +	duty_data = mul_u64_u32_div(state->duty_cycle, ddata->clk_rate,
> NSEC_PER_SEC);
> > +	if (!duty_data)
> > +		return -EINVAL;
> > +
> > +	if (duty_data > U32_MAX)
> > +		duty_data = U32_MAX;
> > +
> > +	ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC,
> (u32)duty_data);
> 
> ditto.
> 
...
> > +	ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm,
> REG_OCPWM_CTRL);
> > +	if (state->enabled)
> > +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> > +				  ctrl_data | REG_OCPWM_CNTR_EN |
> REG_OCPWM_CNTR_OE);
> > +	else
> > +		ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> > +				  ctrl_data & ~(REG_OCPWM_CNTR_EN |
> REG_OCPWM_CNTR_OE));
> 
> If you're clearing REG_OCPWM_CNTR_OE (Output Enable?), does the output
> really go low? Or is that due to an external pull down on your board?
> 
The output will really go low.
> > +
> > +	return 0;
> > +}
> > [...]
> > +static int ocores_pwm_probe(struct platform_device *pdev) {
> > +	const struct of_device_id *id;
> > +	struct device *dev = &pdev->dev;
> > +	struct ocores_pwm_device *ddata;
> > +	struct pwm_chip *chip;
> > +	struct clk *clk;
> > +	struct reset_control *rst;
> > +	int ret;
> > +
> > +	id = of_match_device(ocores_pwm_of_match, dev);
> > +	if (!id)
> > +		return -EINVAL;
> 
> Error message here? Better use device_get_match_data() here. Then you don't
> need the of-specific headers (IIUC).
> 
Will update.
> > +	chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*ddata));
> > +	if (IS_ERR(chip))
> > +		return -ENOMEM;
> > +
> > +	ddata = chip_to_ocores(chip);
> > +	ddata->data = id->data;
> > +	chip->ops = &ocores_pwm_ops;
> > +
> > +	ddata->regs = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(ddata->regs))
> > +		return dev_err_probe(dev, PTR_ERR(ddata->regs),
> > +				     "Unable to map IO resources\n");
> > +
> > +	clk = devm_clk_get_enabled(dev, NULL);
> > +	if (IS_ERR(clk))
> > +		return dev_err_probe(dev, PTR_ERR(clk),
> > +				     "Unable to get pwm's clock\n");
> > +
> > +	ret = devm_clk_rate_exclusive_get(dev, clk);
> > +	if (ret)
> > +		return ret;
> > +
> > +	rst = devm_reset_control_get_optional_exclusive(dev, NULL);
> > +	if (IS_ERR(rst))
> > +		return dev_err_probe(dev, PTR_ERR(rst),
> > +				     "Unable to get pwm's reset\n");
> > +
> > +	ret = reset_control_deassert(rst);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = devm_add_action_or_reset(dev, ocores_pwm_reset_control_assert,
> rst);
> > +	if (ret)
> > +		return ret;
> 
> If you respin anyhow, switch to
> devm_reset_control_get_optional_exclusive_deasserted(). Up to now this only
> exists in next, but I'd care to apply this is a way that doesn't fail to build then.
> 
Will update.
> > +	ddata->clk_rate = clk_get_rate(clk);
> > +	if (ddata->clk_rate > NSEC_PER_SEC)
> > +		return -EINVAL;
> > +
> > +	ret = devm_pwmchip_add(dev, chip);
> > +	if (ret < 0)
> > +		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
> > +
> > +	return 0;
> > +}
> 
> Best regards
> Uwe