Re: [PATCH v3 2/3] iio: adc: sophgo-saradc: Add driver for Sophgo SARADC

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 31 Jul 2024 14:24:15 +0200
Thomas Bonnefille <thomas.bonnefille@bootlin.com> wrote:

> This adds a driver for the common Sophgo SARADC.
> 
> Signed-off-by: Thomas Bonnefille <thomas.bonnefille@bootlin.com>

One small bug (you will return 1 on an error), and a few minor other comments inline.

Thanks,

Jonathan

> diff --git a/drivers/iio/adc/sophgo-cv18xx-adc.c b/drivers/iio/adc/sophgo-cv18xx-adc.c
> new file mode 100644
> index 000000000000..27e1aac9560f
> --- /dev/null
> +++ b/drivers/iio/adc/sophgo-cv18xx-adc.c
> @@ -0,0 +1,206 @@

> +
> +#define CV18XX_ADC_CTRL_REG			0x04
> +#define		CV18XX_ADC_EN			BIT(0)
> +#define		CV18XX_ADC_SEL(x)		BIT((x) + 4)
> +#define CV18XX_ADC_STATUS_REG			0x08
> +#define		CV18XX_ADC_BUSY			BIT(0)
> +#define CV18XX_ADC_CYC_SET_REG			0x0C
> +/* The default cycle configuration is set to maximize the accuracy */
> +#define		CV18XX_ADC_DEF_STARTUP_CYCLE	0xF
> +#define		CV18XX_ADC_DEF_SAMPLE_WINDOW	(0xF << 8)

define masks for the various fields and use FIELD_PREP()
on those with the default values - but do that inline not up here
where we should only set the masks.

> +#define		CV18XX_ADC_DEF_CLOCK_DIVIDER	(0x1 << 12)
> +#define		CV18XX_ADC_DEF_COMPARE_CYCLE	(0xF << 16)
> +#define CV18XX_ADC_CH_RESULT_REG(x)		(0x10 + 4 * (x))
> +#define		CV18XX_ADC_CH_RESULT		GENMASK(11, 0)
> +#define		CV18XX_ADC_CH_VALID		BIT(15)
> +#define CV18XX_ADC_INTR_EN_REG			0x20
> +#define CV18XX_ADC_INTR_CLR_REG			0x24
> +#define		CV18XX_ADC_INTR_CLR_BIT		BIT(0)
> +#define CV18XX_ADC_INTR_STA_REG			0x28
> +#define		CV18XX_ADC_INTR_STA_BIT		BIT(0)

> +static const struct iio_chan_spec sophgo_channels[] = {
> +	CV18XX_ADC_CHANNEL(1),

why index from 1?  We tend to use 0 as the base, though there is no ABI
requirement to do so.  Hence this is ok, just unusual.

> +	CV18XX_ADC_CHANNEL(2),
> +	CV18XX_ADC_CHANNEL(3),
> +};

> +static int cv18xx_adc_read_raw(struct iio_dev *indio_dev,
> +				  struct iio_chan_spec const *chan,
> +				  int *val, int *val2, long mask)
> +{
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		{

I'd move { to previous line.

That will avoid need to indent another tab for the scope.

> +		struct cv18xx_adc *saradc = iio_priv(indio_dev);
> +		u32 sample;
> +		int ret;

Can move ert into scoped_guard scope.

> +
> +		scoped_guard(mutex, &saradc->lock) {
> +			cv18xx_adc_start_measurement(saradc, chan->scan_index);
> +			ret = cv18xx_adc_wait(saradc);
> +			if (ret < 0)
> +				return ret;
> +
> +			sample = readl(saradc->regs + CV18XX_ADC_CH_RESULT_REG(chan->scan_index));
> +		}
> +		if (!(sample & CV18XX_ADC_CH_VALID))
> +			return -ENODATA;
> +
> +		*val = sample & CV18XX_ADC_CH_RESULT;
> +		return IIO_VAL_INT;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = 3300;
> +		*val2 = 12;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}


> +static int cv18xx_adc_probe(struct platform_device *pdev)
> +{
> +	struct cv18xx_adc *saradc;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*saradc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	saradc = iio_priv(indio_dev);
> +	indio_dev->name = "sophgo-cv18xx-adc";
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &cv18xx_adc_info;
> +	indio_dev->num_channels = ARRAY_SIZE(sophgo_channels);
> +	indio_dev->channels = sophgo_channels;
> +
> +	ret = IS_ERR(devm_clk_get_enabled(&pdev->dev, NULL));
> +	if (ret)

PTR_ERR() not IS_ERR() for the return as you are returning a bool currently
not an error code.  Similar to what you do for the regulator below.

Better to use a local struct clk * and check that rather than convert
directly to the error value.


> +		return ret;
> +
> +	saradc->regs = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(saradc->regs))
> +		return PTR_ERR(saradc->regs);
> +
> +	saradc->irq = platform_get_irq_optional(pdev, 0);
> +	if (saradc->irq >= 0) {
> +		init_completion(&saradc->completion);
> +		ret = devm_request_irq(&pdev->dev, saradc->irq,
> +				       cv18xx_adc_interrupt_handler, 0,
> +				       dev_name(&pdev->dev), saradc);
> +		if (ret)
> +			return ret;
> +
> +		writel(1, saradc->regs + CV18XX_ADC_INTR_EN_REG);
> +	}
> +
> +	ret = devm_mutex_init(&pdev->dev, &saradc->lock);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +	writel(CV18XX_ADC_DEF_STARTUP_CYCLE |
> +	       CV18XX_ADC_DEF_SAMPLE_WINDOW |
> +	       CV18XX_ADC_DEF_CLOCK_DIVIDER |
> +	       CV18XX_ADC_DEF_COMPARE_CYCLE
> +	       , saradc->regs + CV18XX_ADC_CYC_SET_REG);

Blank line here. + that leading comma should be on end of the line above.

> +	return devm_iio_device_register(&pdev->dev, indio_dev);
> +
No blank line here.
> +}