Re: [PATCH v16] pwm: opencores: Add PWM driver support

From: Uwe Kleine-König
Date: Thu Dec 19 2024 - 16:00:49 EST


Hello,

On Mon, Oct 28, 2024 at 09:46:09AM +0800, William Qiu wrote:
> +static int ocores_pwm_apply(struct pwm_chip *chip,
> + struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct ocores_pwm_device *ddata = chip_to_ocores(chip);
> + u32 ctrl_data = 0;
> + u64 period_data, duty_data;
> +
> + if (state->polarity != PWM_POLARITY_INVERSED)
> + return -EINVAL;
> +
> + period_data = mul_u64_u32_div(state->period, ddata->clk_rate, NSEC_PER_SEC);
> + if (!period_data)
> + return -EINVAL;
> +
> + if (period_data > U32_MAX)
> + period_data = U32_MAX;
> +
> + ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_LRC, period_data);
> +
> + duty_data = mul_u64_u32_div(state->duty_cycle, ddata->clk_rate, NSEC_PER_SEC);
> + if (!duty_data)
> + return -EINVAL;

I can understand that period_data == 0 is an error, but duty_data == 0
could/should just work?!

> +
> + if (duty_data > U32_MAX)
> + duty_data = U32_MAX;
> +
> + ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_HRC, duty_data);
> +
> + ctrl_data = ocores_pwm_readl(ddata, pwm->hwpwm, REG_OCPWM_CTRL);
> + if (state->enabled)
> + ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> + ctrl_data | REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE);
> + else
> + ocores_pwm_writel(ddata, pwm->hwpwm, REG_OCPWM_CTRL,
> + ctrl_data & ~(REG_OCPWM_CNTR_EN | REG_OCPWM_CNTR_OE));
> +
> + return 0;
> +}
> [...]
> +static int ocores_pwm_probe(struct platform_device *pdev)
> +{
> + const struct of_device_id *id;
> + struct device *dev = &pdev->dev;
> + struct ocores_pwm_device *ddata;
> + struct pwm_chip *chip;
> + struct clk *clk;
> + struct reset_control *rst;
> + int ret;
> +
> + id = of_device_get_match_data(&pdev->dev);
> + if (!id)
> + return -ENODEV;
> +
> + chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*ddata));
> + if (IS_ERR(chip))
> + return -ENOMEM;
> +
> + ddata = chip_to_ocores(chip);
> + ddata->data = id->data;
> + chip->ops = &ocores_pwm_ops;
> +
> + ddata->regs = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(ddata->regs))
> + return dev_err_probe(dev, PTR_ERR(ddata->regs),
> + "Unable to map IO resources\n");
> +
> + clk = devm_clk_get_enabled(dev, NULL);
> + if (IS_ERR(clk))
> + return dev_err_probe(dev, PTR_ERR(clk),
> + "Unable to get pwm's clock\n");
> +
> + ret = devm_clk_rate_exclusive_get(dev, clk);
> + if (ret)
> + return ret;
> +
> + rst = devm_reset_control_get_optional_exclusive(dev, NULL);
> + if (IS_ERR(rst))
> + return dev_err_probe(dev, PTR_ERR(rst),
> + "Unable to get pwm's reset\n");
> +
> + ret = reset_control_deassert(rst);
> + if (ret)
> + return ret;
> +
> + ret = devm_add_action_or_reset(dev, ocores_pwm_reset_control_assert, rst);
> + if (ret)
> + return ret;
> +
> + ddata->clk_rate = clk_get_rate(clk);
> + if (ddata->clk_rate > NSEC_PER_SEC)
> + return -EINVAL;

Missing error messages for the three checks above.

> + ret = devm_pwmchip_add(dev, chip);
> + if (ret < 0)
> + return dev_err_probe(dev, ret, "Could not register PWM chip\n");
> +
> + return 0;
> +}

Best regards
Uwe

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