Re: [PATCH 2/3] iio: adc: at91-sama5d2_adc: add hw trigger and buffer support

[Jonathan Cameron <jic23@kernel.org>]

On 19/04/17 09:20, Eugen Hristev wrote:
> Added support for the external hardware trigger on pin ADTRG,
> integrated the three possible edge triggers into the subsystem
> and created buffer management for data retrieval
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 207 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 204 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index e10dca3..09a8c3d 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -23,8 +23,15 @@
>  #include <linux/platform_device.h>
>  #include <linux/sched.h>
>  #include <linux/wait.h>
> +#include <linux/slab.h>
> +
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +
>  #include <linux/regulator/consumer.h>
>  
>  /* Control Register */
> @@ -132,6 +139,17 @@
>  #define AT91_SAMA5D2_PRESSR	0xbc
>  /* Trigger Register */
>  #define AT91_SAMA5D2_TRGR	0xc0
> +/* Mask for TRGMOD field of TRGR register */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_MASK GENMASK(2, 0)
> +/* No trigger, only software trigger can start conversions */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER 0
> +/* Trigger Mode external trigger rising edge */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_RISE 1
> +/* Trigger Mode external trigger falling edge */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL 2
> +/* Trigger Mode external trigger any edge */
> +#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY 3
> +
>  /* Correction Select Register */
>  #define AT91_SAMA5D2_COSR	0xd0
>  /* Correction Value Register */
> @@ -145,14 +163,20 @@
>  /* Version Register */
>  #define AT91_SAMA5D2_VERSION	0xfc
>  
> +#define AT91_SAMA5D2_HW_TRIG_CNT 3
> +#define AT91_SAMA5D2_SINGLE_CHAN_CNT 12
> +#define AT91_SAMA5D2_DIFF_CHAN_CNT 6
> +
>  #define AT91_SAMA5D2_CHAN_SINGLE(num, addr)				\
>  	{								\
>  		.type = IIO_VOLTAGE,					\
>  		.channel = num,						\
>  		.address = addr,					\
> +		.scan_index = num,					\
>  		.scan_type = {						\
>  			.sign = 'u',					\
>  			.realbits = 12,					\
> +			.storagebits = 16,				\
>  		},							\
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> @@ -168,9 +192,11 @@
>  		.channel = num,						\
>  		.channel2 = num2,					\
>  		.address = addr,					\
> +		.scan_index = num + AT91_SAMA5D2_SINGLE_CHAN_CNT,	\
>  		.scan_type = {						\
>  			.sign = 's',					\
>  			.realbits = 12,					\
> +			.storagebits = 16,				\
>  		},							\
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>  		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> @@ -188,18 +214,26 @@ struct at91_adc_soc_info {
>  	unsigned			max_sample_rate;
>  };
>  
> +struct at91_adc_trigger {
> +	char				*name;
> +	unsigned int			trgmod_value;
> +};
> +
>  struct at91_adc_state {
>  	void __iomem			*base;
>  	int				irq;
>  	struct clk			*per_clk;
>  	struct regulator		*reg;
>  	struct regulator		*vref;
> +	u16				*buffer;
>  	int				vref_uv;
>  	const struct iio_chan_spec	*chan;
>  	bool				conversion_done;
>  	u32				conversion_value;
>  	struct at91_adc_soc_info	soc_info;
>  	wait_queue_head_t		wq_data_available;
> +	struct iio_trigger		**trig;
> +	const struct at91_adc_trigger	*trigger_list;
>  	/*
>  	 * lock to prevent concurrent 'single conversion' requests through
>  	 * sysfs.
> @@ -207,6 +241,21 @@ struct at91_adc_state {
>  	struct mutex			lock;
>  };
>  
> +static const struct at91_adc_trigger at91_adc_trigger_list[] = {
> +	{
> +		.name = "external-rising",
> +		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_RISE,
> +	},
> +	{
> +		.name = "external-falling",
> +		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL,
> +	},
> +	{
> +		.name = "external-any",
> +		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY,
> +	},
> +};
> +
>  static const struct iio_chan_spec at91_adc_channels[] = {
>  	AT91_SAMA5D2_CHAN_SINGLE(0, 0x50),
>  	AT91_SAMA5D2_CHAN_SINGLE(1, 0x54),
> @@ -226,8 +275,141 @@ static const struct iio_chan_spec at91_adc_channels[] = {
>  	AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
>  	AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
>  	AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
> +	IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_SINGLE_CHAN_CNT
> +				+ AT91_SAMA5D2_DIFF_CHAN_CNT + 1),
>  };
>  
> +static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
> +{
> +	struct iio_dev *indio = iio_trigger_get_drvdata(trig);
> +	struct at91_adc_state *st = iio_priv(indio);
> +	u32 status = at91_adc_readl(st, AT91_SAMA5D2_TRGR);
> +	u8 bit;
> +	int i;
> +
> +	/* clear TRGMOD */
> +	status &= ~AT91_SAMA5D2_TRGR_TRGMOD_MASK;
> +
> +	/* if we are disabling the trigger, it's enough to clear TRGMOD */
> +	if (!state) {
> +		at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
> +		kfree(st->buffer);
Would normally expect to see elements related to the buffer in the
preenable callback for the buffer. In this case it might not make
much difference, but that's conceptually where it belongs.
> +		return 0;
> +	}
> +
> +	st->buffer = kmalloc(indio->scan_bytes, GFP_KERNEL);
How big does this get?  I'd be tempted to just use a fixed size big 
enough to take the maximum possible.  Will probably end up more
efficient than allocating it separately.  Not to mention slightly
simplified code.
> +	if (!st->buffer)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < AT91_SAMA5D2_HW_TRIG_CNT; i++) {
> +		if (!strstr(trig->name, st->trigger_list[i].name)) {
> +			status |= st->trigger_list[i].trgmod_value;
> +			break;
> +		}
> +	}
> +
> +	/* setup hw trigger */
> +	at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
> +
> +	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
> +		struct iio_chan_spec const *chan = indio->channels + bit;
> +
> +		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
> +		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct iio_trigger_ops at91_adc_trigger_ops = {
> +	.owner = THIS_MODULE,
> +	.set_trigger_state = &at91_adc_configure_trigger,
> +};
> +
> +static struct iio_trigger *at91_adc_allocate_trigger(struct iio_dev *indio,
> +						     char *trigger_name)
> +{
> +	struct iio_trigger *trig;
> +	int ret;
> +
> +	trig = devm_iio_trigger_alloc(&indio->dev, "%s-dev%d-%s", indio->name,
> +				      indio->id, trigger_name);
> +	if (!trig)
> +		return NULL;
> +
> +	trig->dev.parent = indio->dev.parent;
> +	iio_trigger_set_drvdata(trig, indio);
> +	trig->ops = &at91_adc_trigger_ops;
> +
> +	ret = devm_iio_trigger_register(&indio->dev, trig);
> +
> +	if (ret)
> +		return NULL;
> +
> +	return trig;
> +}
> +
> +static int at91_adc_trigger_init(struct iio_dev *indio)
> +{
> +	struct at91_adc_state *st = iio_priv(indio);
> +	int i;
> +
> +	st->trig = devm_kzalloc(&indio->dev,
> +				AT91_SAMA5D2_HW_TRIG_CNT * sizeof(*st->trig),
> +				GFP_KERNEL);
Given it's a fixed sized allocation, why not just make the resulting array
part of st directly?
> +
> +	if (!st->trig) {
> +		dev_err(&indio->dev, "could not allocate trig list memory\n");
> +		return -ENOMEM;
> +	}
> +
> +	for (i = 0; i < AT91_SAMA5D2_HW_TRIG_CNT; i++) {
> +		st->trig[i] = at91_adc_allocate_trigger(indio,
> +						st->trigger_list[i].name);
> +		if (!st->trig[i]) {
> +			dev_err(&indio->dev,
> +				"could not allocate trigger %d\n", i);
> +			return -ENOMEM;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio = pf->indio_dev;
> +	struct at91_adc_state *st = iio_priv(indio);
> +	int i = 0;
> +	u8 bit;
> +
> +	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
> +		struct iio_chan_spec const *chan = indio->channels + bit;
> +
> +		st->buffer[i] = at91_adc_readl(st, chan->address);
> +		i++;
> +	}
> +
> +	iio_push_to_buffers_with_timestamp(indio, st->buffer, pf->timestamp);
> +
> +	iio_trigger_notify_done(indio->trig);
> +
> +	/* Needed to ACK the DRDY interruption */
> +	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
> +
> +	enable_irq(st->irq);
Unusual to have to disable the irq until this point.  Firstly
if you did need to do this, it should be in the tryreeenable callback.
You haven't restricted this trigger to just this device, so other
drivers could be hanging of it.

Secondly this irq is always defined to be a threaded oneshot irq
so it should be nicely masked anyway.


> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int at91_adc_buffer_init(struct iio_dev *indio)
> +{
> +	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
> +			&iio_pollfunc_store_time,
> +			&at91_adc_trigger_handler, NULL);
This particular wrapper doesn't seem to add much over having it
inline. I'd be tempted to drop it but unimportant if you'd rather
keep it.
> +}
> +
>  static unsigned at91_adc_startup_time(unsigned startup_time_min,
>  				      unsigned adc_clk_khz)
>  {
> @@ -293,14 +475,19 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
>  	u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
>  	u32 imr = at91_adc_readl(st, AT91_SAMA5D2_IMR);
>  
> -	if (status & imr) {
> +	if (!(status & imr))
> +		return IRQ_NONE;
> +
> +	if (iio_buffer_enabled(indio)) {
> +		disable_irq_nosync(irq);
> +		iio_trigger_poll(indio->trig);
> +	} else {
>  		st->conversion_value = at91_adc_readl(st, st->chan->address);
>  		st->conversion_done = true;
>  		wake_up_interruptible(&st->wq_data_available);
> -		return IRQ_HANDLED;
>  	}
>  
> -	return IRQ_NONE;
> +	return IRQ_HANDLED;
>  }
>  
>  static int at91_adc_read_raw(struct iio_dev *indio_dev,
> @@ -406,6 +593,8 @@ static int at91_adc_probe(struct platform_device *pdev)
>  
>  	st = iio_priv(indio_dev);
>  
> +	st->trigger_list = at91_adc_trigger_list;Given it's const, why not just use it directly?
> +
>  	ret = of_property_read_u32(pdev->dev.of_node,
>  				   "atmel,min-sample-rate-hz",
>  				   &st->soc_info.min_sample_rate);
> @@ -499,6 +688,18 @@ static int at91_adc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, indio_dev);
>  
> +	ret = at91_adc_buffer_init(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
> +		goto per_clk_disable_unprepare;
> +	}
> +
> +	ret = at91_adc_trigger_init(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "couldn't setup the triggers.\n");
> +		goto per_clk_disable_unprepare;
> +	}
> +
>  	ret = iio_device_register(indio_dev);
>  	if (ret < 0)
>  		goto per_clk_disable_unprepare;
>