[PATCH 2/3] ARM: AT91: IIO: Add AT91 ADC driver.

[Maxime Ripard]

Hi,

On 20/10/2011 09:09, Lars-Peter Clausen wrote:
> On 10/19/2011 06:18 PM, Maxime Ripard wrote:
>> Cc: Nicolas Ferre <nicolas.ferre at atmel.com>
>> Cc: Patrice Vilchez <patrice.vilchez at atmel.com>
>> Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
>> ---
>>  [...]
>> +
>> +#define at91adc_reg_read(base, reg)        __raw_readl((base) + (reg))
>> +#define at91adc_reg_write(base, reg, val)  __raw_writel((val), (base) + (reg))
> 
> Shouldn't this rather be {readl,writel}_relaxed?

Yep, corrected.

>> +
>> +struct at91adc_state {
>> +	struct clk *clk;
>> +	bool done;
>> +	struct mutex lock;
>> +	struct iio_chan_spec *channels;
>> +	int nb_chan;
>> +	int irq;
>> +	wait_queue_head_t wq_data_avail;
>> +	u16 lcdr;
>> +	void __iomem *reg_base;
>> +
>> +};
>> +
>> +static irqreturn_t at91adc_eoc_trigger(int irq, void *private)
>> +{
>> +	int chan;
>> +	struct at91adc_state *st = private;
>> +	struct iio_dev *idev = iio_priv_to_dev(st);
>> +	unsigned int status = at91adc_reg_read(st->reg_base, AT91_ADC_SR);
>> +
>> +	if (!(status & AT91_ADC_DRDY))
>> +		return IRQ_HANDLED;
>> +
>> +	for (chan = 0; chan < st->nb_chan; chan++) {
>> +		if (status & AT91_ADC_EOC(chan)) {
>> +			st->done = true;
>> +			st->lcdr = at91adc_reg_read(st->reg_base,
>> +						    AT91_ADC_CHR(chan));
>> +		}
>> +	}
>> +	wake_up_interruptible(&st->wq_data_avail);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int at91adc_channel_init(struct at91adc_state *st)
>> +{
>> +	int ret = 0, i;
>> +	st->channels = kzalloc(sizeof(struct iio_chan_spec) * st->nb_chan,
>> +			       GFP_KERNEL);
> 
> kcalloc

Corrected

>> +	if (st->channels == NULL)
>> +		return -ENOMEM;
>> +
>> +	for (i = 0; i < st->nb_chan; i++) {
>> +		struct iio_chan_spec *chan = st->channels + i;
>> +		chan->type = IIO_VOLTAGE;
>> +		chan->indexed = 1;
>> +		chan->channel = i;
> 
> 
> It probably makes sense to initialize scan_type as well.

Ah, didn't see that one, but yeah, you're right.

>> +		++ret;
>> +	}
>> +
>> +	return ret;
> 
> Why do you need ret? Shouldn't this be just st->nb_chan?

The initial plan was to make sure all channels were initialised, but
obviously, my code isn't making such use of ret. You're right.

>> +}
>> +
>> +static int at91adc_read_raw(struct iio_dev *idev,
>> +			    struct iio_chan_spec const *chan,
>> +			    int *val, int *val2, long mask)
>> +{
>> +	struct at91adc_state *st = iio_priv(idev);
>> +
>> +	switch (mask) {
>> +	case 0:
>> +		mutex_lock(&st->lock);
>> +
>> +		at91adc_reg_write(st->reg_base, AT91_ADC_CHER,
>> +				  AT91_ADC_CH(chan->channel));
>> +		at91adc_reg_write(st->reg_base, AT91_ADC_IER,
>> +				  AT91_ADC_EOC(chan->channel));
>> +		at91adc_reg_write(st->reg_base, AT91_ADC_CR, AT91_ADC_START);
>> +
>> +		wait_event_interruptible(st->wq_data_avail, st->done);
> 
> Its probably a good idea to add a timeout in case there is a problem with
> the hardware.

Indeed.

>> +		*val = st->lcdr;
>> +
>> +		at91adc_reg_write(st->reg_base, AT91_ADC_CHDR,
>> +				  AT91_ADC_CH(chan->channel));
>> +		at91adc_reg_write(st->reg_base, AT91_ADC_IDR,
>> +				  AT91_ADC_EOC(chan->channel));
>> +
>> +		st->lcdr = 0;
>> +		st->done = false;
>> +		mutex_unlock(&st->lock);
>> +		return IIO_VAL_INT;
>> +	default:
>> +		break;
>> +	}
>> +	return -EINVAL;
>> +}
>> +
>> +static const struct iio_info at91adc_info = {
>> +	.driver_module = THIS_MODULE,
>> +	.read_raw = &at91adc_read_raw,
>> +};
>> +
>> +static int __devinit at91adc_probe(struct platform_device *pdev)
>> +{
>> +	unsigned int prsc, mstrclk, ticks;
>> +	int ret;
>> +	struct iio_dev *idev;
>> +	struct at91adc_state *st;
>> +	struct resource *res;
>> +	struct at91_adc_data *pdata = pdev->dev.platform_data;
>> +
>> +	dev_dbg(&pdev->dev, "AT91ADC probed\n");
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	if (!res) {
>> +		dev_err(&pdev->dev, "No resource defined\n");
>> +		ret = -ENXIO;
>> +		goto error_ret;
>> +	}
>> +
>> +	idev = iio_allocate_device(sizeof(*st));
>> +	if (idev == NULL) {
>> +		dev_err(&pdev->dev, "Failed to allocate memory.\n");
>> +		ret = -ENOMEM;
>> +		goto error_ret;
>> +	}
>> +	platform_set_drvdata(pdev, idev);
>> +
>> +	idev->dev.parent = &pdev->dev;
>> +	idev->name = platform_get_device_id(pdev)->name;
> 
> You don't use device ids. This should cause a NULL pointer deref? Maybe use
> dev_name(&pdev->dev) instead.

Ok.

>> +	idev->modes = INDIO_DIRECT_MODE;
>> +	idev->info = &at91adc_info;
>> +
>> +[...]
>> +}
>> +
>> +static int __devexit at91adc_remove(struct platform_device *pdev)
>> +{
>> +	struct iio_dev *idev = platform_get_drvdata(pdev);
>> +	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	struct at91adc_state *st = iio_priv(idev);
>> +
>> +	free_irq(st->irq, st);
>> +	iounmap(st->reg_base);
>> +	release_mem_region(res->start, resource_size(res));
>> +	iio_device_unregister(idev);
>> +
> 
> The iio API changed a bit recently and uses a two stage unregistration now.
> You should call iio_device_unregister before freeing resources and
> iio_device_free afterwards.

Hmmm, I don't see the iio_device_free in Jonathan's git. Is it
iio_free_device, or should I use another git repo/branch as base ?

Thanks,

-- 
Maxime Ripard, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com