Re: [PATCH v2 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC

From: Jingbao Qiu
Date: Tue Feb 20 2024 - 06:45:48 EST

On Tue, Feb 20, 2024 at 6:48 PM Uwe Kleine-König
<u.kleine-koenig@xxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> On Mon, Feb 12, 2024 at 08:17:29PM +0800, Jingbao Qiu wrote:
> > Implement the PWM driver for CV1800.
> >
> > Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@xxxxxxxxx>
> > ---
> > drivers/pwm/Kconfig | 10 ++
> > drivers/pwm/Makefile | 1 +
> > drivers/pwm/pwm-cv1800.c | 248 +++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 259 insertions(+)
> > create mode 100644 drivers/pwm/pwm-cv1800.c
> >
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > index 4b956d661755..455f07af94f7 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -186,6 +186,16 @@ config PWM_CROS_EC
> > PWM driver for exposing a PWM attached to the ChromeOS Embedded
> > Controller.
> >
> > +config PWM_CV1800
> > + tristate "Sophgo CV1800 PWM driver"
> > + depends on ARCH_SOPHGO || COMPILE_TEST
> > + help
> > + Generic PWM framework driver for the Sophgo CV1800 series
> > + SoCs.
> > +
> > + To compile this driver as a module, build the dependecies
> > + as modules, this will be called pwm-cv1800.
> > +
> > config PWM_DWC_CORE
> > tristate
> > depends on HAS_IOMEM
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > index c5ec9e168ee7..6c3c4a07a316 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -15,6 +15,7 @@ obj-$(CONFIG_PWM_CLK) += pwm-clk.o
> > obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
> > obj-$(CONFIG_PWM_CRC) += pwm-crc.o
> > obj-$(CONFIG_PWM_CROS_EC) += pwm-cros-ec.o
> > +obj-$(CONFIG_PWM_CV1800) += pwm-cv1800.o
> > obj-$(CONFIG_PWM_DWC_CORE) += pwm-dwc-core.o
> > obj-$(CONFIG_PWM_DWC) += pwm-dwc.o
> > obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o
> > diff --git a/drivers/pwm/pwm-cv1800.c b/drivers/pwm/pwm-cv1800.c
> > new file mode 100644
> > index 000000000000..3d7f2ff3a6c2
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-cv1800.c
> > @@ -0,0 +1,248 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * pwm-cv1800.c: PWM driver for Sophgo cv1800
> > + *
> > + * Author: Jingbao Qiu <qiujingbao.dlmu@xxxxxxxxx>
> > + *
> > + * Limitations:
> > + * - It output low when PWM channel disabled.
> > + * - This pwm device supports dynamic loading of PWM parameters. When PWMSTART
> > + * is written from 0 to 1, the register value (HLPERIODn, PERIODn) will be
> > + * temporarily stored inside the PWM. If you want to dynamically change the
> > + * waveform during PWM output, after writing the new value to HLPERIODn and
> > + * PERIODn, write 1 and then 0 to PWMUPDATE[n] to make the new value effective.
> > + * - Supports up to Rate/2 output, and the lowest is about Rate/(2^30-1).
> > + * - By setting HLPERIODn to 0, can produce 100% duty cycle.
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pwm.h>
> > +#include <linux/regmap.h>
> > +
> > +#define PWM_CV1800_HLPERIOD_BASE 0x00
> > +#define PWM_CV1800_PERIOD_BASE 0x04
> > +#define PWM_CV1800_PWM_CV1800_POLARITY 0x40
> > +#define PWM_CV1800_START 0x44
> > +#define PWM_CV1800_DONE 0x48
> > +#define PWM_CV1800_UPDATE 0x4c
> > +#define PWM_CV1800_OE 0xd0
> > +#define PWM_CV1800_HLPERIOD_SHIFT 0x08
> > +#define PWM_CV1800_PERIOD_SHIFT 0x08
> > +
> > +#define PWM_CV1800_HLPERIOD(n) \
> > + (PWM_CV1800_HLPERIOD_BASE + ((n) * PWM_CV1800_HLPERIOD_SHIFT))
> > +#define PWM_CV1800_PERIOD(n) \
> > + (PWM_CV1800_PERIOD_BASE + ((n) * PWM_CV1800_PERIOD_SHIFT))
>
> I would have used a plain 0x08 instead of PWM_CV1800_HLPERIOD_SHIFT and
> PWM_CV1800_PERIOD_SHIFT.

I will fix it.

>
> > +#define PWM_CV1800_UPDATE_MASK(n) (BIT(0) << (n))
> > +#define PWM_CV1800_OE_MASK(n) (BIT(0) << (n))
> > +#define PWM_CV1800_START_MASK(n) (BIT(0) << (n))
> > +
> > +#define PWM_CV1800_MAXPERIOD (BIT(30) - 1)
> > +#define PWM_CV1800_MINPERIOD BIT(1)
> > +#define PWM_CV1800_MINHLPERIOD BIT(0)
> > +#define PWM_CV1800_PERIOD_RESET BIT(1)
> > +#define PWM_CV1800_HLPERIOD_RESET BIT(0)
> > +#define PWM_CV1800_REG_DISABLE 0x0U
> > +#define PWM_CV1800_REG_ENABLE(n) (BIT(0) << (n))
> > +
> > +struct cv1800_pwm {
> > + struct pwm_chip chip;
> > + struct regmap *map;
> > + struct clk *clk;
> > + unsigned long clk_rate;
> > +};
> > +
> > +static const struct regmap_config cv1800_pwm_regmap_config = {
> > + .reg_bits = 32,
> > + .val_bits = 32,
> > + .reg_stride = 4,
> > +};
> > +
> > +static inline struct cv1800_pwm *to_cv1800_pwm_dev(struct pwm_chip *chip)
> > +{
> > + return container_of(chip, struct cv1800_pwm, chip);
>
> Please rework the driver to use pwmchip_alloc(). See
> https://lore.kernel.org/linux-pwm/a37a167364366b6cbe2dd299dce02731706213b2.1707900770.git.u.kleine-koenig@xxxxxxxxxxxxxx/T/#u
> for a simple example for such a rework.
>

I will fix it.

> > +}
> > +
> > +static int cv1800_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm,
> > + bool enable)
> > +{
> > + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> > + u32 pwm_enable;
> > +
> > + regmap_read(priv->map, PWM_CV1800_START, &pwm_enable);
> > + pwm_enable &= PWM_CV1800_START_MASK(pwm->hwpwm);
> > +
> > + /*
> > + * If the parameters are changed during runtime, Register needs
> > + * to be updated to take effect.
> > + */
> > + if (pwm_enable && enable) {
> > + regmap_update_bits(priv->map, PWM_CV1800_UPDATE,
> > + PWM_CV1800_UPDATE_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> > + regmap_update_bits(priv->map, PWM_CV1800_UPDATE,
> > + PWM_CV1800_UPDATE_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_DISABLE);
> > + } else if (!pwm_enable && enable) {
> > + regmap_update_bits(priv->map, PWM_CV1800_OE,
> > + PWM_CV1800_OE_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> > + regmap_update_bits(priv->map, PWM_CV1800_START,
> > + PWM_CV1800_START_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> > + } else if (pwm_enable && !enable) {
> > + regmap_update_bits(priv->map, PWM_CV1800_OE,
> > + PWM_CV1800_OE_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_DISABLE);
> > + regmap_update_bits(priv->map, PWM_CV1800_START,
> > + PWM_CV1800_START_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_DISABLE);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int cv1800_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > + const struct pwm_state *state)
> > +{
> > + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> > + u32 period_val, hlperiod_val;
> > + u64 tem;
> > +
> > + if (state->polarity != PWM_POLARITY_NORMAL)
> > + return -EINVAL;
> > +
> > + tem = mul_u64_u64_div_u64(state->period, priv->clk_rate, NSEC_PER_SEC);
> > + if (tem > PWM_CV1800_MAXPERIOD || tem < PWM_CV1800_MINPERIOD)
> > + return -EINVAL;
>
> Please use:
>
> if (tem < PWM_CV1800_MINPERIOD)
> return -EINVAL
> if (tem > PWM_CV1800_MAXPERIOD)
> tem = PWM_CV1800_MAXPERIOD;
>

I will fix it.

> > + period_val = (u32)tem;
> > +
> > + tem = mul_u64_u64_div_u64(state->period - state->duty_cycle,
> > + priv->clk_rate, NSEC_PER_SEC);
>
> Given that you're supposed to configure the biggest duty_cycle not
> bigger than the requested value, you have to round up here.
>

I will fix it.
Thank you for your patient reply.

Best regards
Jingbao Qiu