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

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Message-ID: <ZtYh6xUcP8zo3xMj@surfacebook.localdomain>
Date: Mon, 2 Sep 2024 23:36:59 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Thomas Bonnefille <thomas.bonnefille@...tlin.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Chen Wang <unicorn_wang@...look.com>,
	Inochi Amaoto <inochiama@...look.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Miquèl Raynal <miquel.raynal@...tlin.com>,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v5 2/3] iio: adc: sophgo-saradc: Add driver for Sophgo
 CV1800B SARADC

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

...

> +#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)

...

> +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.

> +}
> +
> +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

> +		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'.

> +	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?

> +		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.

> +	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

> +		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)

> +	}
> +
> +	ret = devm_mutex_init(&pdev->dev, &saradc->lock);
> +	if (ret)
> +		return ret;

+ blank line?

> +	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);
> +}

-- 
With Best Regards,
Andy Shevchenko