linux-kernel - Re: [PATCH v5 1/2] iio: adc: add driver for Rockchip saradc

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Date:	Sun, 20 Jul 2014 13:23:55 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Heiko Stübner <heiko@...ech.de>,
	Jonathan Cameron <jic23@...nel.org>
CC:	Peter Meerwald <pmeerw@...erw.net>,
	Hartmut Knaack <knaack.h@....de>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"eddie(蔡枫)" <cf@...k-chips.com>,
	huangtao@...k-chips.com
Subject: Re: [PATCH v5 1/2] iio: adc: add driver for Rockchip saradc

On 07/14/2014 10:43 PM, Heiko Stübner wrote:

Looks really good overall.

[...]
> +static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
> +				    struct iio_chan_spec const *chan,
> +				    int *val, int *val2, long mask)
> +{
> +	struct rockchip_saradc *info = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&indio_dev->mlock);
> +
> +		/* 8 clock periods as delay between power up and start cmd */
> +		writel_relaxed(8, info->regs + SARADC_DLY_PU_SOC);
> +

It makes sense to call reinit_completion() here.

> +		/* Select the channel to be used and trigger conversion */
> +		writel(SARADC_CTRL_POWER_CTRL
> +				| (chan->channel & SARADC_CTRL_CHN_MASK)
> +				| SARADC_CTRL_IRQ_ENABLE,
> +		       info->regs + SARADC_CTRL);
> +
> +		if (!wait_for_completion_timeout(&info->completion,
> +						 SARADC_TIMEOUT)) {
> +			writel_relaxed(0, info->regs + SARADC_CTRL);
> +			mutex_unlock(&indio_dev->mlock);
> +			return -ETIMEDOUT;
> +		}
> +
> +		*val = info->last_val;
> +		mutex_unlock(&indio_dev->mlock);
> +		return IIO_VAL_INT;
[...]
> +static int rockchip_saradc_probe(struct platform_device *pdev)
> +{
> +	struct rockchip_saradc *info = NULL;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct iio_dev *indio_dev = NULL;
> +	struct resource	*mem;
> +	int ret;
> +	int irq;
> +	u32 rate;
> +
> +	if (!np)
> +		return -ENODEV;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
> +	if (!indio_dev) {
> +		dev_err(&pdev->dev, "failed allocating iio device\n");
> +		return -ENOMEM;
> +	}
> +	info = iio_priv(indio_dev);
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	info->regs = devm_request_and_ioremap(&pdev->dev, mem);

devm_request_and_ioremap() is deprecated an will be removed in the next 
release[1]. Use devm_ioremap_resource(), note that devm_ioremap_resource() 
returns a ERR_PTR instead of NULL on error.

[1] https://lkml.org/lkml/2014/6/11/26

> +	if (!info->regs)
> +		return -ENOMEM;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "no irq resource?\n");
> +		return irq;
> +	}
> +
> +	ret = devm_request_irq(&pdev->dev, irq, rockchip_saradc_isr,
> +			       0, dev_name(&pdev->dev), info);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed requesting irq %d\n", irq);
> +		return ret;
> +	}
> +
> +	init_completion(&info->completion);

Since the completion is used in the interrupt callback it must be 
initialized before the interrupt is requested.

> +
[...]
> +	/* use a default of 1MHz for the converter clock */
> +	ret = of_property_read_u32(np, "clock-frequency", &rate);
> +	if (ret < 0)
> +		rate = 1000000;

Should this really be in the devicetree or shouldn't this be user 
configurable at runtime?

[...]
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