Re: [PATCH v5 2/3] iio: adc: sophgo-saradc: Add driver for Sophgo CV1800B SARADC

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 2 Sep 2024 23:36:59 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> Thu, Aug 29, 2024 at 02:31:51PM +0200, Thomas Bonnefille kirjoitti:
> > This adds a driver for the Sophgo CV1800B SARADC.  
> 
> Jonathan, please consider the below improvements to be folded in as well.
> 
> ...
> 
> + array_size.h
> 
> > +#include <linux/bitfield.h>  
> 
> + bits.h
> + cleanup.h
> 
> > +#include <linux/clk.h>
> > +#include <linux/completion.h>  
> 
> + err.h
> 
> > +#include <linux/interrupt.h>  
> 
> > +#include <linux/iio/iio.h>  
> 
> I would split it into a separate group already.
> 
> > +#include <linux/iopoll.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/platform_device.h>  
> 
> + types.h
Added. 

> 
> ...
> 
> > +#define CV1800B_READ_TIMEOUT_MS				1000
> > +#define CV1800B_READ_TIMEOUT_US				(CV1800B_READ_TIMEOUT_MS * 1000)  
> 
> Effectively these may be written as
> 
> (1 * MSEC_PER_SEC)
> (1 * USEC_PER_SEC)
> 
> ...
I'm not going to make this one.  Sure good feedback but not worth fixing
and chance I mess it up.

> 
> > +static int cv1800b_adc_wait(struct cv1800b_adc *saradc)
> > +{
> > +	if (saradc->irq < 0) {
> > +		u32 reg;
> > +
> > +		return readl_poll_timeout(saradc->regs + CV1800B_ADC_STATUS_REG,
> > +					  reg, !(reg & CV1800B_ADC_BUSY),
> > +					  500, CV1800B_READ_TIMEOUT_US);
> > +	}
> > +
> > +	return wait_for_completion_timeout(&saradc->completion,
> > +					  msecs_to_jiffies(CV1800B_READ_TIMEOUT_MS)) > 0
> > +					  ? 0 : -ETIMEDOUT;  
> 
> Usually we leave "?" part on the previous line.
Moved.
Also the line above is one space short of alignment.

> 
> > +}
> > +
> > +static int cv1800b_adc_read_raw(struct iio_dev *indio_dev,
> > +				struct iio_chan_spec const *chan,
> > +				int *val, int *val2, long mask)
> > +{
> > +	struct cv1800b_adc *saradc = iio_priv(indio_dev);
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:{  
> 
> Missing space
I'd already fixed that one.
> 
> > +		u32 sample;
> > +
> > +		scoped_guard(mutex, &saradc->lock) {
> > +			int ret;
> > +
> > +			cv1800b_adc_start_measurement(saradc, chan->scan_index);
> > +			ret = cv1800b_adc_wait(saradc);
> > +			if (ret < 0)
> > +				return ret;
> > +
> > +			sample = readl(saradc->regs + CV1800B_ADC_CH_RESULT_REG(chan->scan_index));
> > +		}
> > +		if (!(sample & CV1800B_ADC_CH_VALID))
> > +			return -ENODATA;
> > +
> > +		*val = sample & CV1800B_ADC_CH_RESULT;
> > +		return IIO_VAL_INT;
> > +		}  
> 
> This should be indented as 'c' in the above 'case'.
True. Fixed up.

> 
> > +	case IIO_CHAN_INFO_SCALE:
> > +		*val = 3300;
> > +		*val2 = 12;
> > +		return IIO_VAL_FRACTIONAL_LOG2;
> > +	case IIO_CHAN_INFO_SAMP_FREQ:
> > +		u32 status_reg = readl(saradc->regs + CV1800B_ADC_CYC_SET_REG);  
> 
> > +		int clk_div = (1 + FIELD_GET(CV1800B_MASK_CLKDIV, status_reg));
> > +		int freq = clk_get_rate(saradc->clk) / clk_div;  
> 
> Why are these signed?
Made them unsigned. Seems safe enough

> 
> > +		int nb_startup_cycle = 1 + FIELD_GET(CV1800B_MASK_STARTUP_CYCLE, status_reg);
> > +		int nb_sample_cycle = 1 + FIELD_GET(CV1800B_MASK_SAMPLE_WINDOW, status_reg);
> > +		int nb_compare_cycle = 1 + FIELD_GET(CV1800B_MASK_COMPARE_CYCLE, status_reg);
> > +
> > +		*val = freq / (nb_startup_cycle + nb_sample_cycle + nb_compare_cycle);
> > +		return IIO_VAL_INT;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +}  
> 
> ...
> 
> > +static int cv1800b_adc_probe(struct platform_device *pdev)
> > +{  
> 
> Having
> 
> 	struct device *dev = &pdev->dev;
> 
> here helps making below code neater.
sure. modified.

> 
> > +	struct cv1800b_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-cv1800b-adc";
> > +	indio_dev->modes = INDIO_DIRECT_MODE;
> > +	indio_dev->info = &cv1800b_adc_info;
> > +	indio_dev->num_channels = ARRAY_SIZE(sophgo_channels);
> > +	indio_dev->channels = sophgo_channels;
> > +
> > +	saradc->clk = devm_clk_get_enabled(&pdev->dev, NULL);
> > +	if (IS_ERR(saradc->clk))
> > +		return PTR_ERR(saradc->clk);
> > +
> > +	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) {  
> 
> '=' is redundant
removed.
> 
> > +		init_completion(&saradc->completion);
> > +		ret = devm_request_irq(&pdev->dev, saradc->irq,
> > +				       cv1800b_adc_interrupt_handler, 0,
> > +				       dev_name(&pdev->dev), saradc);
> > +		if (ret)
> > +			return ret;
> > +
> > +		writel(1, saradc->regs + CV1800B_ADC_INTR_EN_REG);  
> 
> BIT(0)

Maybe on that - would need to compare with datasheet to know how it's
described. In theory that might not be a mask.

> 
> > +	}
> > +
> > +	ret = devm_mutex_init(&pdev->dev, &saradc->lock);
> > +	if (ret)
> > +		return ret;  
> 
> + blank line?
That one I'd done already.
Anyhow tweaked and pushed out again.


Jonathan

> 
> > +	writel(FIELD_PREP(CV1800B_MASK_STARTUP_CYCLE, 15) |
> > +	       FIELD_PREP(CV1800B_MASK_SAMPLE_WINDOW, 15) |
> > +	       FIELD_PREP(CV1800B_MASK_CLKDIV, 1) |
> > +	       FIELD_PREP(CV1800B_MASK_COMPARE_CYCLE, 15),
> > +	       saradc->regs + CV1800B_ADC_CYC_SET_REG);
> > +
> > +	return devm_iio_device_register(&pdev->dev, indio_dev);
> > +}  
>