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Message-ID: <ZwTsTQiTkFFu3pwX@gofer.mess.org>
Date: Tue, 8 Oct 2024 09:24:45 +0100
From: Sean Young <sean@...s.org>
To: Chen Wang <unicornxw@...il.com>
Cc: ukleinek@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
conor+dt@...nel.org, unicorn_wang@...look.com,
inochiama@...look.com, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org,
linux-riscv@...ts.infradead.org, chao.wei@...hgo.com,
haijiao.liu@...hgo.com, xiaoguang.xing@...hgo.com,
chunzhi.lin@...hgo.com
Subject: Re: [PATCH v3 2/3] pwm: sophgo: add driver for Sophgo SG2042 PWM
On Tue, Oct 08, 2024 at 11:04:14AM +0800, Chen Wang wrote:
> From: Chen Wang <unicorn_wang@...look.com>
>
> Add a PWM driver for PWM controller in Sophgo SG2042 SoC.
>
> Signed-off-by: Chen Wang <unicorn_wang@...look.com>
> ---
> drivers/pwm/Kconfig | 10 ++
> drivers/pwm/Makefile | 1 +
> drivers/pwm/pwm-sophgo-sg2042.c | 180 ++++++++++++++++++++++++++++++++
> 3 files changed, 191 insertions(+)
> create mode 100644 drivers/pwm/pwm-sophgo-sg2042.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 0915c1e7df16..ec85f3895936 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -584,6 +584,16 @@ config PWM_SL28CPLD
> To compile this driver as a module, choose M here: the module
> will be called pwm-sl28cpld.
>
> +config PWM_SOPHGO_SG2042
> + tristate "Sophgo SG2042 PWM support"
> + depends on ARCH_SOPHGO || COMPILE_TEST
> + help
> + PWM driver for the PWM controller on Sophgo SG2042 SoC. The PWM
> + controller supports outputing 4 channels of PWM waveforms.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called pwm_sophgo_sg2042.
> +
> config PWM_SPEAR
> tristate "STMicroelectronics SPEAr PWM support"
> depends on PLAT_SPEAR || COMPILE_TEST
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 9081e0c0e9e0..539e0def3f82 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -53,6 +53,7 @@ obj-$(CONFIG_PWM_RZ_MTU3) += pwm-rz-mtu3.o
> obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
> obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
> obj-$(CONFIG_PWM_SL28CPLD) += pwm-sl28cpld.o
> +obj-$(CONFIG_PWM_SOPHGO_SG2042) += pwm-sophgo-sg2042.o
> obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o
> obj-$(CONFIG_PWM_SPRD) += pwm-sprd.o
> obj-$(CONFIG_PWM_STI) += pwm-sti.o
> diff --git a/drivers/pwm/pwm-sophgo-sg2042.c b/drivers/pwm/pwm-sophgo-sg2042.c
> new file mode 100644
> index 000000000000..198019b751ad
> --- /dev/null
> +++ b/drivers/pwm/pwm-sophgo-sg2042.c
> @@ -0,0 +1,180 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Sophgo SG2042 PWM Controller Driver
> + *
> + * Copyright (C) 2024 Sophgo Technology Inc.
> + * Copyright (C) 2024 Chen Wang <unicorn_wang@...look.com>
> + *
> + * Limitations:
> + * - After reset, the output of the PWM channel is always high.
> + * The value of HLPERIOD/PERIOD is 0.
> + * - When HLPERIOD or PERIOD is reconfigured, PWM will start to
> + * output waveforms with the new configuration after completing
> + * the running period.
> + * - When PERIOD and HLPERIOD is set to 0, the PWM wave output will
> + * be stopped and the output is pulled to high.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +
> +#include <asm/div64.h>
> +
> +/*
> + * Offset RegisterName
> + * 0x0000 HLPERIOD0
> + * 0x0004 PERIOD0
> + * 0x0008 HLPERIOD1
> + * 0x000C PERIOD1
> + * 0x0010 HLPERIOD2
> + * 0x0014 PERIOD2
> + * 0x0018 HLPERIOD3
> + * 0x001C PERIOD3
> + * Four groups and every group is composed of HLPERIOD & PERIOD
> + */
> +#define SG2042_HLPERIOD(chan) ((chan) * 8 + 0)
> +#define SG2042_PERIOD(chan) ((chan) * 8 + 4)
> +
> +#define SG2042_PWM_CHANNELNUM 4
> +
> +/**
> + * struct sg2042_pwm_ddata - private driver data
> + * @base: base address of mapped PWM registers
> + * @clk_rate_hz: rate of base clock in HZ
> + */
> +struct sg2042_pwm_ddata {
> + void __iomem *base;
> + unsigned long clk_rate_hz;
> +};
> +
> +static void pwm_sg2042_config(void __iomem *base, unsigned int chan, u32 period, u32 hlperiod)
> +{
> + writel(period, base + SG2042_PERIOD(chan));
> + writel(hlperiod, base + SG2042_HLPERIOD(chan));
> +}
> +
> +static int pwm_sg2042_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct sg2042_pwm_ddata *ddata = pwmchip_get_drvdata(chip);
> + u32 hlperiod;
> + u32 period;
> +
> + if (state->polarity == PWM_POLARITY_INVERSED)
> + return -EINVAL;
> +
> + if (!state->enabled) {
> + pwm_sg2042_config(ddata->base, pwm->hwpwm, 0, 0);
> + return 0;
> + }
> +
> + /*
> + * Period of High level (duty_cycle) = HLPERIOD x Period_clk
> + * Period of One Cycle (period) = PERIOD x Period_clk
> + */
> + period = min(mul_u64_u64_div_u64(ddata->clk_rate_hz, state->period, NSEC_PER_SEC), U32_MAX);
> + hlperiod = min(mul_u64_u64_div_u64(ddata->clk_rate_hz, state->duty_cycle, NSEC_PER_SEC), U32_MAX);
> +
> + if (hlperiod > period) {
> + dev_err(pwmchip_parent(chip), "period < hlperiod, failed to apply current setting\n");
> + return -EINVAL;
> + }
> +
> + dev_dbg(pwmchip_parent(chip), "chan[%u]: period=%u, hlperiod=%u\n",
> + pwm->hwpwm, period, hlperiod);
> +
> + pwm_sg2042_config(ddata->base, pwm->hwpwm, period, hlperiod);
> +
> + return 0;
> +}
> +
> +static int pwm_sg2042_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> + struct pwm_state *state)
> +{
> + struct sg2042_pwm_ddata *ddata = pwmchip_get_drvdata(chip);
> + unsigned int chan = pwm->hwpwm;
> + u32 hlperiod;
> + u32 period;
> +
> + period = readl(ddata->base + SG2042_PERIOD(chan));
> + hlperiod = readl(ddata->base + SG2042_HLPERIOD(chan));
> +
> + if (!period && !hlperiod)
> + state->enabled = false;
> + else
> + state->enabled = true;
> +
> + state->period = DIV_ROUND_UP_ULL((u64)period * NSEC_PER_SEC, ddata->clk_rate_hz);
> + state->duty_cycle = DIV_ROUND_UP_ULL((u64)hlperiod * NSEC_PER_SEC, ddata->clk_rate_hz);
> +
> + state->polarity = PWM_POLARITY_NORMAL;
> +
> + return 0;
> +}
> +
> +static const struct pwm_ops pwm_sg2042_ops = {
> + .apply = pwm_sg2042_apply,
> + .get_state = pwm_sg2042_get_state,
> +};
> +
> +static const struct of_device_id sg2042_pwm_ids[] = {
> + { .compatible = "sophgo,sg2042-pwm" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, sg2042_pwm_ids);
> +
> +static int pwm_sg2042_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct sg2042_pwm_ddata *ddata;
> + struct pwm_chip *chip;
> + struct clk *clk;
> + int ret;
> +
> + chip = devm_pwmchip_alloc(dev, SG2042_PWM_CHANNELNUM, sizeof(*ddata));
> + if (IS_ERR(chip))
> + return PTR_ERR(chip);
> + ddata = pwmchip_get_drvdata(chip);
> +
> + ddata->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(ddata->base))
> + return PTR_ERR(ddata->base);
> +
> + clk = devm_clk_get_enabled(dev, "apb");
> + if (IS_ERR(clk))
> + return dev_err_probe(dev, PTR_ERR(clk), "failed to get base clk\n");
> +
> + ret = devm_clk_rate_exclusive_get(dev, clk);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to get exclusive rate\n");
> +
> + ddata->clk_rate_hz = clk_get_rate(clk);
> + if (!ddata->clk_rate_hz || ddata->clk_rate_hz > NSEC_PER_SEC)
> + return dev_err_probe(dev, -EINVAL,
> + "Invalid clock rate: %lu\n", ddata->clk_rate_hz);
> +
> + chip->ops = &pwm_sg2042_ops;
I think you can add here:
chip->atomic = true;
As far as I can see, the driver does not do any sleeping operations
in pwm_sg2042_apply(). This probably should be tested with
CONFIG_PWM_DEBUG and CONFIG_DEBUG_ATOMIC_SLEEP just to be sure.
Thanks,
Sean
> +
> + ret = devm_pwmchip_add(dev, chip);
> + if (ret < 0)
> + return dev_err_probe(dev, ret, "failed to register PWM chip\n");
> +
> + return 0;
> +}
> +
> +static struct platform_driver pwm_sg2042_driver = {
> + .driver = {
> + .name = "sg2042-pwm",
> + .of_match_table = sg2042_pwm_ids,
> + },
> + .probe = pwm_sg2042_probe,
> +};
> +module_platform_driver(pwm_sg2042_driver);
> +
> +MODULE_AUTHOR("Chen Wang");
> +MODULE_DESCRIPTION("Sophgo SG2042 PWM driver");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>
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