Re: [PATCH v1 2/2] pwm: starfive: Add PWM driver support

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

On 2023/2/28 22:34, Krzysztof Kozlowski wrote:
> On 28/02/2023 10:13, William Qiu wrote:
>> Add Pulse Width Modulation driver support for StarFive
>> JH7110 soc.
>> 
>> Signed-off-by: Hal Feng <hal.feng@starfivetech.com>
>> Signed-off-by: William Qiu <william.qiu@starfivetech.com>
>> ---
>>  MAINTAINERS                    |   7 +
>>  drivers/pwm/Kconfig            |  10 ++
>>  drivers/pwm/Makefile           |   1 +
>>  drivers/pwm/pwm-starfive-ptc.c | 256 +++++++++++++++++++++++++++++++++
>>  4 files changed, 274 insertions(+)
>>  create mode 100644 drivers/pwm/pwm-starfive-ptc.c
>> 
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index ac151975d0d3..05b59605d864 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -19929,6 +19929,13 @@ F:	drivers/pinctrl/starfive/pinctrl-starfive-jh71*
>>  F:	include/dt-bindings/pinctrl/pinctrl-starfive-jh7100.h
>>  F:	include/dt-bindings/pinctrl/starfive,jh7110-pinctrl.h
>>  
>> +STARFIVE JH71X0 PWM DRIVERS
>> +M:	William Qiu <william.qiu@starfivetech.com>
>> +M:	Hal Feng <hal.feng@starfivetech.com>
>> +S:	Supported
>> +F:	Documentation/devicetree/bindings/pwm/pwm-starfive.yaml
>> +F:	drivers/pwm/pwm-starfive-ptc.c
>> +
>>  STARFIVE JH71X0 RESET CONTROLLER DRIVERS
>>  M:	Emil Renner Berthing <kernel@esmil.dk>
>>  M:	Hal Feng <hal.feng@starfivetech.com>
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index dae023d783a2..2307a0099994 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -536,6 +536,16 @@ config PWM_SPRD
>>  	  To compile this driver as a module, choose M here: the module
>>  	  will be called pwm-sprd.
>>  
>> +config PWM_STARFIVE_PTC
>> +	tristate "StarFive PWM PTC support"
>> +	depends on OF
>> +	depends on COMMON_CLK
>> +	help
>> +	  Generic PWM framework driver for StarFive SoCs.
>> +
>> +	  To compile this driver as a module, choose M here: the module
>> +	  will be called pwm-starfive-ptc.
>> +
>>  config PWM_STI
>>  	tristate "STiH4xx PWM support"
>>  	depends on ARCH_STI || COMPILE_TEST
>> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
>> index 7bf1a29f02b8..577f69904baa 100644
>> --- a/drivers/pwm/Makefile
>> +++ b/drivers/pwm/Makefile
>> @@ -49,6 +49,7 @@ obj-$(CONFIG_PWM_SIFIVE)	+= pwm-sifive.o
>>  obj-$(CONFIG_PWM_SL28CPLD)	+= pwm-sl28cpld.o
>>  obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
>>  obj-$(CONFIG_PWM_SPRD)		+= pwm-sprd.o
>> +obj-$(CONFIG_PWM_STARFIVE_PTC)	+= pwm-starfive-ptc.o
>>  obj-$(CONFIG_PWM_STI)		+= pwm-sti.o
>>  obj-$(CONFIG_PWM_STM32)		+= pwm-stm32.o
>>  obj-$(CONFIG_PWM_STM32_LP)	+= pwm-stm32-lp.o
>> diff --git a/drivers/pwm/pwm-starfive-ptc.c b/drivers/pwm/pwm-starfive-ptc.c
>> new file mode 100644
>> index 000000000000..58831c600168
>> --- /dev/null
>> +++ b/drivers/pwm/pwm-starfive-ptc.c
>> @@ -0,0 +1,256 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * PWM driver for the StarFive JH7110 SoC
>> + *
>> + * Copyright (C) 2018 StarFive Technology Co., Ltd.
>> + */
>> +
>> +#include <dt-bindings/pwm/pwm.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pwm.h>
>> +#include <linux/slab.h>
>> +#include <linux/clk.h>
>> +#include <linux/reset.h>
>> +#include <linux/io.h>
>> +
>> +/* how many parameters can be transferred to ptc */
>> +#define OF_PWM_N_CELLS			3
>> +
>> +/* PTC Register offsets */
>> +#define REG_RPTC_CNTR			0x0
>> +#define REG_RPTC_HRC			0x4
>> +#define REG_RPTC_LRC			0x8
>> +#define REG_RPTC_CTRL			0xC
>> +
>> +/* Bit for PWM clock */
>> +#define BIT_PWM_CLOCK_EN		31
>> +
>> +/* Bit for clock gen soft reset */
>> +#define BIT_CLK_GEN_SOFT_RESET		13
>> +
>> +#define NS_PER_SECOND			1000000000
>> +#define DEFAULT_FREQ_HZ			2000000
> 
> Drop unused defines.
> 
Will drop.
>> +
>> +/*
>> + * Access PTC register (cntr hrc lrc and ctrl),
>> + * need to replace PWM_BASE_ADDR
>> + */
>> +#define REG_PTC_BASE_ADDR_SUB(base, N)	\
>> +((base) + (((N) > 3) ? (((N) % 4) * 0x10 + (1 << 15)) : ((N) * 0x10)))
>> +#define REG_PTC_RPTC_CNTR(base, N)	(REG_PTC_BASE_ADDR_SUB(base, N))
>> +#define REG_PTC_RPTC_HRC(base, N)	(REG_PTC_BASE_ADDR_SUB(base, N) + 0x4)
>> +#define REG_PTC_RPTC_LRC(base, N)	(REG_PTC_BASE_ADDR_SUB(base, N) + 0x8)
>> +#define REG_PTC_RPTC_CTRL(base, N)	(REG_PTC_BASE_ADDR_SUB(base, N) + 0xC)
>> +
>> +/* PTC_RPTC_CTRL */
>> +#define PTC_EN      BIT(0)
>> +#define PTC_ECLK    BIT(1)
>> +#define PTC_NEC     BIT(2)
>> +#define PTC_OE      BIT(3)
>> +#define PTC_SIGNLE  BIT(4)
>> +#define PTC_INTE    BIT(5)
>> +#define PTC_INT     BIT(6)
>> +#define PTC_CNTRRST BIT(7)
>> +#define PTC_CAPTE   BIT(8)
>> +
>> +struct starfive_pwm_ptc_device {
>> +	struct pwm_chip		chip;
>> +	struct clk		*clk;
>> +	struct reset_control	*rst;
>> +	void __iomem		*regs;
>> +	int			irq;
>> +	/*pwm apb clock frequency*/
> 
> Missing spaces. Use Linux coding style.
> 
Will fix.
>> +	unsigned int		approx_freq;
>> +};
>> +
>> +static inline struct starfive_pwm_ptc_device *
>> +		chip_to_starfive_ptc(struct pwm_chip *c)
>> +{
>> +	return container_of(c, struct starfive_pwm_ptc_device, chip);
>> +}
>> +
> 
> (...)
> 
>> +static int starfive_pwm_ptc_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct starfive_pwm_ptc_device *pwm;
>> +	struct pwm_chip *chip;
>> +	struct resource *res;
>> +	unsigned int clk_apb_freq;
>> +	int ret;
>> +
>> +	pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL);
>> +	if (!pwm)
>> +		return -ENOMEM;
>> +
>> +	chip = &pwm->chip;
>> +	chip->dev = dev;
>> +	chip->ops = &starfive_pwm_ptc_ops;
>> +	chip->npwm = 8;
>> +
>> +	chip->of_pwm_n_cells = OF_PWM_N_CELLS;
>> +	chip->base = -1;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	pwm->regs = devm_ioremap_resource(dev, res);
> 
> Combine these two, there is a helper for it.
> 
Will update.
>> +	if (IS_ERR(pwm->regs)) {
>> +		dev_err(dev, "Unable to map IO resources\n");
> 
> return dev_err_probe(), everywhere probably.
> 
Will fix.
>> +		return PTR_ERR(pwm->regs);
>> +	}
>> +
>> +	pwm->clk = devm_clk_get(dev, NULL);
>> +	if (IS_ERR(pwm->clk)) {
>> +		dev_err(dev, "Unable to get pwm clock\n");
>> +		return PTR_ERR(pwm->clk);
>> +	}
>> +
>> +	pwm->rst = devm_reset_control_get_exclusive(dev, NULL);
>> +	if (IS_ERR(pwm->rst)) {
>> +		dev_err(dev, "Unable to get pwm reset\n");
>> +		return PTR_ERR(pwm->rst);
>> +	}
>> +
>> +	ret = clk_prepare_enable(pwm->clk);
>> +	if (ret) {
>> +		dev_err(dev,
>> +			"Failed to enable pwm clock, %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	reset_control_deassert(pwm->rst);
>> +
>> +	clk_apb_freq = (unsigned int)clk_get_rate(pwm->clk);
> 
> Why do you need this local variable? And why the cast?
> 
Will drop this local variable.
>> +	if (!clk_apb_freq)
>> +		dev_warn(dev,
>> +			 "get pwm apb clock rate failed.\n");
> 
> and pwm->approx_freq stays 0 which you later use for dividing. Did you
> actually test it? It should produce big splat...
> 
Will update.
>> +	else
>> +		pwm->approx_freq = clk_apb_freq;
>> +
>> +	ret = pwmchip_add(chip);
> 
> devm
> 
Will update.
>> +	if (ret < 0) {
>> +		dev_err(dev, "cannot register PTC: %d\n", ret);
>> +		clk_disable_unprepare(pwm->clk);
>> +		return ret;
>> +	}
>> +
>> +	platform_set_drvdata(pdev, pwm);
>> +
>> +	return 0;
>> +}
>> +
>> +static int starfive_pwm_ptc_remove(struct platform_device *dev)
>> +{
>> +	struct starfive_pwm_ptc_device *pwm = platform_get_drvdata(dev);
>> +	struct pwm_chip *chip = &pwm->chip;
>> +
>> +	pwmchip_remove(chip);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id starfive_pwm_ptc_of_match[] = {
>> +	{ .compatible = "starfive,jh7110-pwm" },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, starfive_pwm_ptc_of_match);
>> +
>> +static struct platform_driver starfive_pwm_ptc_driver = {
>> +	.probe = starfive_pwm_ptc_probe,
>> +	.remove = starfive_pwm_ptc_remove,
>> +	.driver = {
>> +		.name = "pwm-starfive-ptc",
>> +		.of_match_table = of_match_ptr(starfive_pwm_ptc_of_match),
> 
> of_match_ptr goes with maybe_unused, which you do not have. Anyway I am
> not sure what's the benefit of having it here, so just drop it.
> 
Will drop.
Thank you for spending time reviewing and providing helpful comments
for this driver

Best regards
William
> Best regards,
> Krzysztof
>