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Message-ID: <twzx4abuhduos5s32txeugqr2yyca6ey7adcontsnapthwqaxa@dscea3ybrlym>
Date: Mon, 4 Mar 2024 16:37:02 +0100
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: Jingbao Qiu <qiujingbao.dlmu@...il.com>
Cc: robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
conor+dt@...nel.org, paul.walmsley@...ive.com, palmer@...belt.com,
aou@...s.berkeley.edu, linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, dlan@...too.org,
inochiama@...look.com
Subject: Re: [PATCH v4 2/2] pwm: sophgo: add pwm support for Sophgo CV1800 SoC
Hello,
thanks for your patch.
On Mon, Mar 04, 2024 at 05:02:48PM +0800, Jingbao Qiu wrote:
> Implement the PWM driver for CV1800.
>
> Signed-off-by: Jingbao Qiu <qiujingbao.dlmu@...il.com>
> ---
> drivers/pwm/Kconfig | 10 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-cv1800.c | 314 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 325 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..d5b31a2b7787
> --- /dev/null
> +++ b/drivers/pwm/pwm-cv1800.c
> @@ -0,0 +1,314 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * pwm-cv1800.c: PWM driver for Sophgo cv1800
Mentioning the filename in the file isn't very helpful. It's obvious
information.
> + * Author: Jingbao Qiu <qiujingbao.dlmu@...il.com>
> + *
> + * 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_OE_INPUT 0x00U
> +#define PWM_CV1800_OE_OUTPUT(n) (BIT(0) << (n))
> +#define PWM_CV1800_MAXPERIOD (BIT(30) - 1)
> +#define PWM_CV1800_MINPERIOD BIT(1)
These are minimal and maximal values. I'd do
#define PWM_CV1800_MAXPERIOD 0x3fffffff
#define PWM_CV1800_MINPERIOD 2
> +#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))
> +#define PWM_CV1800_CHANNELS 4
> +
> +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);
> +
> + if (pwm->state.enabled)
> + cv1800_pwm_enable(chip, pwm, !pwm->state.enabled);
> +
> + if (polarity == PWM_POLARITY_INVERSED)
> + regmap_update_bits(priv->map, PWM_CV1800_POLARITY,
> + PWM_CV1800_POLARITY_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> + else
> + regmap_update_bits(priv->map, PWM_CV1800_POLARITY,
> + PWM_CV1800_POLARITY_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_DISABLE);
Wouldn't it be more natural to make this read:
if (polarity == PWM_POLARITY_INVERSED)
regmap_update_bits(priv->map, PWM_CV1800_POLARITY,
PWM_CV1800_POLARITY_MASK(pwm->hwpwm),
PWM_CV1800_POLARITY_MASK(pwm->hwpwm));
else
regmap_update_bits(priv->map, PWM_CV1800_POLARITY,
PWM_CV1800_POLARITY_MASK(pwm->hwpwm),
0);
or even:
u32 polarity = 0;
if (polarity == PWM_POLARITY_INVERSED)
polarity = PWM_CV1800_POLARITY_MASK(pwm->hwpwm);
regmap_update_bits(priv->map, PWM_CV1800_POLARITY,
PWM_CV1800_POLARITY_MASK(pwm->hwpwm),
polarity);
?
> +}
> +
> +static void cv1800_pwm_set_oe(struct pwm_chip *chip, struct pwm_device *pwm,
> + u32 mode)
> +{
> + 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;
> +
> + cv1800_pwm_enable(chip, pwm, false);
> +
> + if (mode == PWM_CV1800_OE_INPUT)
> + regmap_update_bits(priv->map, PWM_CV1800_OE,
> + PWM_CV1800_OE_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_DISABLE);
> + else if (mode == PWM_CV1800_OE_OUTPUT(pwm->hwpwm))
> + regmap_update_bits(priv->map, PWM_CV1800_OE,
> + PWM_CV1800_OE_MASK(pwm->hwpwm),
> + PWM_CV1800_REG_ENABLE(pwm->hwpwm));
> +}
What does this function do? A comment describing that would be good. I
wonder about it being called unconditionally in .apply() below.
> +
> +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;
> +
> + cv1800_pwm_set_oe(chip, pwm, PWM_CV1800_OE_OUTPUT(pwm->hwpwm));
> +
> + if (state->polarity != pwm->state.polarity)
> + cv1800_pwm_set_polarity(chip, pwm, state->polarity);
> +
> + /*
> + * 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
> + */
> + tem = mul_u64_u64_div_u64(state->period, priv->clk_rate, NSEC_PER_SEC);
What does "tem" stand for? Maybe "ticks" is a better name?
> + if (tem < PWM_CV1800_MINPERIOD)
> + return -EINVAL;
> +
> + if (tem > PWM_CV1800_MAXPERIOD)
> + tem = PWM_CV1800_MAXPERIOD;
> +
> + period_val = (u32)tem;
> +
> + /*
> + * The meaning of HLPERIOD is the number of beats in the low or high level
> + * of the PERIOD. When the value of the POLARITY register is 0, HLPERIOD
> + * represents a low level.
> + * HLPERIOD = period_val - rate(MHz) / duty(MHz)
> + * HLPERIOD = period_val - duty(ns) * rate(Hz) / NSEC_PER_SEC
So HLPERIOD defines the second part of each period, right? This isn't
considered in .get_state().
> + */
> + tem = mul_u64_u64_div_u64(state->duty_cycle, priv->clk_rate,
> + NSEC_PER_SEC);
> + if (tem > period_val)
> + return -EINVAL;
if (tem > period_val)
tem = period_val;
> + hlperiod_val = period_val - (u32)tem;
Wrong rounding I think. Did you test your driver with PWM_DEBUG enabled?
> + 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;
> + u32 polarity = 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);
> +
> + regmap_read(priv->map, PWM_CV1800_POLARITY, &polarity);
> + polarity &= PWM_CV1800_POLARITY_MASK(pwm->hwpwm);
> + }
> +
> + state->period = period_ns;
> + state->duty_cycle = duty_ns;
> + state->enabled = enable;
> + state->polarity = polarity ? PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
> +
> + 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, PWM_CV1800_CHANNELS, sizeof(*priv));
> + if (!chip)
> + return PTR_ERR(chip);
> + priv = to_cv1800_pwm_dev(chip);
> +
> + base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + priv->map = devm_regmap_init_mmio(&pdev->dev, base,
> + &cv1800_pwm_regmap_config);
> + if (IS_ERR(priv->map))
> + return PTR_ERR(priv->map);
> +
> + priv->clk = devm_clk_get_enabled(&pdev->dev, NULL);
> + if (IS_ERR(priv->clk))
> + return dev_err_probe(&pdev->dev, PTR_ERR(priv->clk),
> + "clk not found\n");
> +
> + ret = clk_rate_exclusive_get(priv->clk);
There is a devm_clk_rate_exclusive_get() in next. Please make use of it.
(See commit b0cde62e4c54)
> + if (ret)
> + return dev_err_probe(&pdev->dev, ret,
> + "failed to get exclusive rate\n");
> +
> + ret = devm_add_action_or_reset(&pdev->dev, devm_clk_rate_exclusive_put,
> + priv->clk);
> + if (ret) {
> + clk_rate_exclusive_put(priv->clk);
> + return ret;
> + }
> +
> + priv->clk_rate = clk_get_rate(priv->clk);
> + if (!priv->clk_rate)
> + return dev_err_probe(&pdev->dev, -EINVAL,
> + "Invalid clock rate: %lu\n",
> + priv->clk_rate);
> +
> + chip->ops = &cv1800_pwm_ops;
> +
> + return devm_pwmchip_add(dev, chip);
Error message if devm_pwmchip_add() fails, please.
> +}
> +
> +static const struct of_device_id cv1800_pwm_dt_ids[] = {
> + { .compatible = "sophgo,cv1800-pwm" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, cv1800_pwm_dt_ids);
> +
> +static struct platform_driver cv1800_pwm_driver = {
> + .probe = cv1800_pwm_probe,
> + .driver = {
> + .name = "cv1800-pwm",
> + .of_match_table = cv1800_pwm_dt_ids,
> + },
> +};
> +module_platform_driver(cv1800_pwm_driver);
> +
> +MODULE_AUTHOR("Jingbao Qiu");
> +MODULE_DESCRIPTION("Sophgo cv1800 PWM Driver");
> +MODULE_LICENSE("GPL");
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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