Re: [PATCH v5 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC

From: Jingbao Qiu
Date: Sat Mar 16 2024 - 03:13:46 EST

On Sat, Mar 16, 2024 at 9:55 AM Jisheng Zhang <jszhang@xxxxxxxxxx> wrote:
>
> On Thu, Mar 14, 2024 at 06:01:31PM +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 | 315 +++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 326 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..8eca07c60942
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-cv1800.c
> > @@ -0,0 +1,315 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Sophgo CV1800 PWM driver
> > + * 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.
> > + * - This hardware could support inverted polarity. By default, the value of the
> > + * POLARITY register is 0x0. This means that HLPERIOD represents the number
> > + * of low level beats.
> > + * - This hardware supports input mode and output mode, implemented through the
> > + * Output-Enable/OE register. However, this driver has not yet implemented
> > + * capture callback.
> > + */
> > +
> > +#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_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(n) (PWM_CV1800_HLPERIOD_BASE + ((n) * 0x08))
> > +#define PWM_CV1800_PERIOD(n) (PWM_CV1800_PERIOD_BASE + ((n) * 0x08))
> > +
> > +#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_POLARITY_MASK(n) (BIT(0) << (n))
> > +
> > +#define PWM_CV1800_MAXPERIOD 0x3fffffff
> > +#define PWM_CV1800_MINPERIOD 2
> > +#define PWM_CV1800_CHANNELS 4
> > +#define PWM_CV1800_PERIOD_RESET BIT(1)
> > +#define PWM_CV1800_HLPERIOD_RESET BIT(0)
> > +#define PWM_CV1800_REG_DISABLE 0x00U
> > +#define PWM_CV1800_REG_ENABLE(n) (BIT(0) << (n))
> > +
> > +struct cv1800_pwm {
> > + struct regmap *map;
> > + struct clk *clk;
> > + unsigned long clk_rate;
> > +};
> > +
> > +static inline struct cv1800_pwm *to_cv1800_pwm_dev(struct pwm_chip *chip)
> > +{
> > + return pwmchip_get_drvdata(chip);
> > +}
> > +
> > +static const struct regmap_config cv1800_pwm_regmap_config = {
> > + .reg_bits = 32,
> > + .val_bits = 32,
> > + .reg_stride = 4,
> > +};
> > +
> > +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_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_START,
> > + PWM_CV1800_START_MASK(pwm->hwpwm),
> > + PWM_CV1800_REG_DISABLE);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void cv1800_pwm_set_polarity(struct pwm_chip *chip,
> > + struct pwm_device *pwm,
> > + enum pwm_polarity polarity)
> > +{
> > + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> > + u32 config_polarity = 0;
> > +
> > + if (pwm->state.enabled)
> > + cv1800_pwm_enable(chip, pwm, !pwm->state.enabled);
> > +
> > + if (polarity == PWM_POLARITY_INVERSED)
> > + config_polarity = PWM_CV1800_POLARITY_MASK(pwm->hwpwm);
> > +
> > + regmap_update_bits(priv->map, PWM_CV1800_POLARITY,
> > + PWM_CV1800_POLARITY_MASK(pwm->hwpwm),
> > + config_polarity);
> > +}
> > +
> > +/**
> > + * cv1800_pwm_set_oe() - check and config nth channal output-enable/OE mode
> > + * @chip: PWM chip
> > + * @pwm: PWM device
> > + * @mode: The nth bit of the mode represents the output-enable/OE mode
> > + * of the nth channal. 1 represents output mode, 0 represents
> > + * input mode.
> > + */
> > +static void cv1800_pwm_set_oe(struct pwm_chip *chip, struct pwm_device *pwm,
> > + u32 mode)
>
> Did you get any information about the capture support pwm controller?
>
> > +{
> > + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> > + u32 state;
> > +
> > + regmap_read(priv->map, PWM_CV1800_OE, &state);
> > + state &= PWM_CV1800_OE_MASK(pwm->hwpwm);
> > +
> > + if (state == mode)
> > + return;
> > +
> > + /* disenable pwm output before changing output mode */
> > + cv1800_pwm_enable(chip, pwm, false);
> > +
> > + regmap_update_bits(priv->map, PWM_CV1800_OE,
> > + PWM_CV1800_OE_MASK(pwm->hwpwm), mode);
> > +}
> > +
> > +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 ticks;
> > +
> > + cv1800_pwm_set_oe(chip, pwm, PWM_CV1800_OE_MASK(pwm->hwpwm));
>
> If no capture support, I don't think we need to take care OE, could it
> be done during init?
>

Currently, there is no support for capturing callbacks. you're right,
by default, the
channel is in the output state, it can be initialized as an output
state in the probe.
I will carefully consider your opinion.

Best regards,
Jingbao Qiu