Re: [PATCH v8 2/4] pwm: opencores: Add PWM driver support

[William Qiu <william.qiu@starfivetech.com>]

On 2023/11/29 18:25, Philipp Zabel wrote:
> On Mi, 2023-11-29 at 17:27 +0800, William Qiu wrote:
>> 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 | 232 +++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 252 insertions(+)
>>  create mode 100644 drivers/pwm/pwm-ocores.c
>> 
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 012df8ccf34e..ae6a7be47bc9 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -16206,6 +16206,13 @@ 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 4b956d661755..d87e1bb350ba 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -444,6 +444,18 @@ config PWM_NTXEC
>>  	  controller found in certain e-book readers designed by the original
>>  	  design manufacturer Netronix.
>>  
>> +config PWM_OCORES
>> +	tristate "OpenCores PWM support"
>> +	depends on HAS_IOMEM && OF
>> +	depends on COMMON_CLK && RESET_CONTROLLER
>> +	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 c5ec9e168ee7..517c4f643058 100644
>> --- a/drivers/pwm/Makefile
>> +++ b/drivers/pwm/Makefile
>> @@ -40,6 +40,7 @@ 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..d96318b18570
>> --- /dev/null
>> +++ b/drivers/pwm/pwm-ocores.c
>> @@ -0,0 +1,232 @@
>> +// 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 do inverted polarity.
>> + * - The hardware minimum period / duty_cycle is (1 / pwm_apb clock frequency) ns.
>> + * - The hardware maximum period / duty_cycle is (U32_MAX / pwm_apb clock frequency) ns.
>> + */
>> +
>> +#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>
>> +
>> +/* OCPWM_CTRL register bits*/
>> +#define REG_OCPWM_EN      BIT(0)
>> +#define REG_OCPWM_ECLK    BIT(1)
>> +#define REG_OCPWM_NEC     BIT(2)
>> +#define REG_OCPWM_OE      BIT(3)
>> +#define REG_OCPWM_SIGNLE  BIT(4)
>> +#define REG_OCPWM_INTE    BIT(5)
>> +#define REG_OCPWM_INT     BIT(6)
>> +#define REG_OCPWM_CNTRRST BIT(7)
>> +#define REG_OCPWM_CAPTE   BIT(8)
>> +
>> +struct ocores_pwm_device {
>> +	struct pwm_chip chip;
>> +	struct clk *clk;
>> +	struct reset_control *rst;
>> +	const struct ocores_pwm_data *data;
>> +	void __iomem *regs;
>> +	u32 clk_rate; /* PWM APB clock frequency */
>> +};
>> +
>> +struct ocores_pwm_data {
>> +	void __iomem *(*get_ch_base)(void __iomem *base, unsigned int channel);
>> +};
>> +
>> +static inline u32 ocores_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_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 container_of(chip, struct ocores_pwm_device, chip);
>> +}
>> +
>> +static void __iomem *starfive_jh71x0_get_ch_base(void __iomem *base,
>> +						 unsigned int channel)
>> +{
>> +	unsigned int offset = (channel > 3 ? 1 << 15 : 0) + (channel & 3) * 0x10;
>> +
>> +	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_readl(ddata, pwm->hwpwm, 0x8);
>> +	duty_data = ocores_readl(ddata, pwm->hwpwm, 0x4);
>> +	ctrl_data = ocores_readl(ddata, pwm->hwpwm, 0xC);
>> +
>> +	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_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;
>> +
>> +	ctrl_data = ocores_readl(ddata, pwm->hwpwm, 0xC);
>> +	ocores_writel(ddata, pwm->hwpwm, 0xC, 0);
>> +
>> +	period_data = DIV_ROUND_DOWN_ULL(state->period * ddata->clk_rate, NSEC_PER_SEC);
>> +	if (period_data <= U32_MAX)
>> +		ocores_writel(ddata, pwm->hwpwm, 0x8, (u32)period_data);
>> +	else
>> +		return -EINVAL;
>> +
>> +	duty_data = DIV_ROUND_DOWN_ULL(state->duty_cycle * ddata->clk_rate, NSEC_PER_SEC);
>> +	if (duty_data <= U32_MAX)
>> +		ocores_writel(ddata, pwm->hwpwm, 0x4, (u32)duty_data);
>> +	else
>> +		return -EINVAL;
>> +
>> +	ocores_writel(ddata, pwm->hwpwm, 0xC, 0);
>> +
>> +	if (state->enabled) {
>> +		ctrl_data = ocores_readl(ddata, pwm->hwpwm, 0xC);
>> +		ocores_writel(ddata, pwm->hwpwm, 0xC, ctrl_data | REG_OCPWM_EN | REG_OCPWM_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 jh7100_pwm_data = {
>> +	.get_ch_base = starfive_jh71x0_get_ch_base,
>> +};
>> +
>> +static const struct ocores_pwm_data jh7110_pwm_data = {
>> +	.get_ch_base = starfive_jh71x0_get_ch_base,
>> +};
>> +
>> +static const struct of_device_id ocores_pwm_of_match[] = {
>> +	{ .compatible = "opencores,pwm-v1" },
>> +	{ .compatible = "starfive,jh7100-pwm", .data = &jh7100_pwm_data},
>> +	{ .compatible = "starfive,jh7110-pwm", .data = &jh7110_pwm_data},
>> +	{ /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, ocores_pwm_of_match);
>> +
>> +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;
>> +	int ret;
>> +
>> +	id = of_match_device(ocores_pwm_of_match, dev);
>> +	if (!id)
>> +		return -EINVAL;
>> +
>> +	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
>> +	if (!ddata)
>> +		return -ENOMEM;
>> +
>> +	ddata->data = id->data;
>> +	chip = &ddata->chip;
>> +	chip->dev = dev;
>> +	chip->ops = &ocores_pwm_ops;
>> +	chip->npwm = 8;
>> +	chip->of_pwm_n_cells = 3;
>> +
>> +	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");
>> +
>> +	ddata->clk = devm_clk_get_enabled(dev, NULL);
>> +	if (IS_ERR(ddata->clk))
>> +		return dev_err_probe(dev, PTR_ERR(ddata->clk),
>> +				     "Unable to get pwm's clock\n");
>> +
>> +	ddata->rst = devm_reset_control_get_optional_exclusive(dev, NULL);
>> +	reset_control_deassert(ddata->rst);
> 
> You could use devm_add_action_or_reset() to add reset assertion for
> driver removal and the error paths here, allowing to drop
> ocores_pwm_remove() and ...
> 
I see. I would use devm_add_action_or_reset(), and drop redundant code.
>> +	ddata->clk_rate = clk_get_rate(ddata->clk);
>> +	if (ddata->clk_rate <= 0)
>> +		return dev_err_probe(dev, ddata->clk_rate,
>> +				     "Unable to get clock's rate\n");
> 
> ... then this wouldn't leave the reset deasserted ...
> 
...
>> +
>> +	ret = devm_pwmchip_add(dev, chip);
>> +	if (ret < 0) {
>> +		reset_control_assert(ddata->rst);
> 
> ... and this could be dropped.
> 
...
>> +		clk_disable_unprepare(ddata->clk);
> 
> This can be dropped, devm_clk_get_enabled() already disables the clock
> on probe error.
> 
Will drop.
>> +		return dev_err_probe(dev, ret, "Could not register PWM chip\n");
>> +	}
>> +
>> +	platform_set_drvdata(pdev, ddata);
>> +
>> +	return ret;
>> +}
>> +
>> +static void ocores_pwm_remove(struct platform_device *dev)
>> +{
>> +	struct ocores_pwm_device *ddata = platform_get_drvdata(dev);
>> +
>> +	reset_control_assert(ddata->rst);
>> +	clk_disable_unprepare(ddata->clk);
> 
> Drop as well, devm_clk_get_enabled() already disables the clock on
> driver removal.
> 
I will drop all remove() interface.

Thank you for taking time to review this patchset.

Best Regards,
William
> regards
> Philipp