Re: [PATCH v3 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC

From: Jingbao Qiu
Date: Mon Feb 26 2024 - 23:52:09 EST

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In reply to: Jisheng Zhang: "Re: [PATCH v3 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC"
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On Mon, Feb 26, 2024 at 10:15 PM Jisheng Zhang <jszhang@xxxxxxxxxx> wrote:
>
> On Fri, Feb 23, 2024 at 04:26:32PM +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 | 259 +++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 270 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..da1309dc0091
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-cv1800.c
> > @@ -0,0 +1,259 @@
> > +// 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(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_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 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);
>
> what's the reason of using regmap?

This hardware has 4 channels, which means there may be
multiple PWM channels working simultaneously. These PWM
channels share some registers, such as PWMSTART, POLARITY.
So I use regmap.

>
> > + 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,
>
> I believe this isn't correct.
> TRM says setting OE as 1 means output enable, while 0 means input.
> So I guess the controller may support pwm capture, but I didn't
> get too much information about pwm capture of the controller from
> the TRM, so can you please check and implement the .capture hook
> if it's supported?

you're right, the value of the OE register in the. apply function is always 1.
I need to modify the value of the PWMSTART register and check the OE
register value. In addition, I will contact the hardware designers regarding
the input mode of PWM hardware and will add support for the .capture
feature after submitting this version

>
> > + 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,
>
> ditto
>
> > + 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;
>
> This is wrong. Per the TRM, The POLARITY(offset 0x040) reg can set the
> polarity, so both PWM_POLARITY_NORMAL and PWM_POLARITY_INVERSED are supported.
>

you're right, because POLARITY defaults to low-level output, HLPERIOD
represents the
number of low-level beats, which has been taken into account in the.
apply calculation
process. For the sake of simplicity, I simply believe that he is
PWM-POLARITY-NORMAL.
I will add support for polarity in the next version.

> > +
> > + /*
> > + * This hardware use PERIOD and HLPERIOD registers to represent PWM waves.
> > + *
> > + * The meaning of PERIOD is how many clock cycles (from the clock source)
> > + * are used to represent PWM waves.
> > + * PERIOD = rate(MHz) / target(MHz)
> > + * PERIOD = period(ns) * rate(Hz) / NSEC_PER_SEC
> > + * The meaning of HLPERIOD is the number of low-level cycles in PERIOD.
> > + * HLPERIOD = PERIOD - rate(MHz) / duty(MHz)
> > + * HLPERIOD = PERIOD - (duty(ns) * rate(Hz) / NSEC_PER_SEC)
> > + */
> > + tem = mul_u64_u64_div_u64(state->period, priv->clk_rate, NSEC_PER_SEC);
> > + if (tem < PWM_CV1800_MINPERIOD)
> > + return -EINVAL;
> > +
> > + if (tem > PWM_CV1800_MAXPERIOD)
> > + tem = PWM_CV1800_MAXPERIOD;
> > +
> > + period_val = (u32)tem;
> > +
> > + tem = mul_u64_u64_div_u64(state->duty_cycle, priv->clk_rate,
> > + NSEC_PER_SEC);
> > + if (tem > period_val)
> > + return -EINVAL;
> > + hlperiod_val = period_val - (u32)tem;
> > +
> > + regmap_write(priv->map, PWM_CV1800_PERIOD(pwm->hwpwm), period_val);
> > + regmap_write(priv->map, PWM_CV1800_HLPERIOD(pwm->hwpwm), hlperiod_val);
> > +
> > + cv1800_pwm_enable(chip, pwm, state->enabled);
> > +
> > + return 0;
> > +}
> > +
> > +static int cv1800_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> > + struct pwm_state *state)
> > +{
> > + struct cv1800_pwm *priv = to_cv1800_pwm_dev(chip);
> > + u32 period_val, hlperiod_val;
> > + u64 period_ns = 0;
> > + u64 duty_ns = 0;
> > + u32 enable = 0;
> > +
> > + regmap_read(priv->map, PWM_CV1800_PERIOD(pwm->hwpwm), &period_val);
> > + regmap_read(priv->map, PWM_CV1800_HLPERIOD(pwm->hwpwm), &hlperiod_val);
> > +
> > + if (period_val != PWM_CV1800_PERIOD_RESET ||
> > + hlperiod_val != PWM_CV1800_HLPERIOD_RESET) {
> > + period_ns = DIV_ROUND_UP_ULL(period_val * NSEC_PER_SEC, priv->clk_rate);
> > + duty_ns = DIV_ROUND_UP_ULL(hlperiod_val * period_ns, period_val);
> > +
> > + regmap_read(priv->map, PWM_CV1800_START, &enable);
> > +
> > + enable &= PWM_CV1800_START_MASK(pwm->hwpwm);
> > + }
> > +
> > + state->period = period_ns;
> > + state->duty_cycle = duty_ns;
> > + state->enabled = enable;
> > + state->polarity = PWM_POLARITY_NORMAL;
>
> This is not correct, see above.
>
> > +
> > + return 0;
> > +}
> > +
> > +static const struct pwm_ops cv1800_pwm_ops = {
> > + .apply = cv1800_pwm_apply,
> > + .get_state = cv1800_pwm_get_state,
> > +};
> > +
> > +static void devm_clk_rate_exclusive_put(void *data)
> > +{
> > + struct clk *clk = data;
> > +
> > + clk_rate_exclusive_put(clk);
> > +}
> > +
> > +static int cv1800_pwm_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct cv1800_pwm *priv;
> > + struct pwm_chip *chip;
> > + void __iomem *base;
> > + int ret;
> > +
> > + chip = devm_pwmchip_alloc(dev, 4, sizeof(*priv));
>
> it's better to replace magic "4" with proper macro.

Yes, that's a good idea.

Best regards
Jingbao Qiu

Next message: Dhruva Gole: "Re: [PATCH v4 0/4] spi: cadence-qspi: Fix runtime PM and system-wide suspend"
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In reply to: Jisheng Zhang: "Re: [PATCH v3 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC"
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