Re: [PATCH v8 3/3] iio: accel: adxl355: Add triggered buffer support
From: Puranjay Mohan
Date: Fri Aug 13 2021 - 04:22:00 EST
On Sun, Aug 8, 2021 at 9:03 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> On Sun, 8 Aug 2021 16:29:36 +0100
> Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> > On Wed, 4 Aug 2021 19:33:09 +0530
> > Puranjay Mohan <puranjay12@xxxxxxxxx> wrote:
> >
> > > Provide a way for continuous data capture by setting up buffer support. The
> > > data ready signal exposed at the DRDY pin of the ADXL355 is exploited as
> > > a hardware interrupt which triggers to fill the buffer.
> > >
> > > Signed-off-by: Puranjay Mohan <puranjay12@xxxxxxxxx>
> >
> > Hi Puranjay,
> >
> > This device has a hardware fifo, so we need to be careful how we add
> > trigger support such that we can enable that smoothly.
> Oops. I meant to come back and add some detail on this after taking a look
> at the datasheet.
>
> The device has an explicit data ready pin to indicate 'any data' not using
> the fifo. That's helpful for this mode. I note that there is a way of
> turning it off which is good and you should ensure it is off, except when
> the trigger is enabled so that we aren't dealing with a stream of spurious
> interrupts.
I have added a function in trigger_ops to enable this, and I have
turned this off in the setup.
>
> I would encourage you to also get the fifo mode up and running before sending
> a new version of this patch. It may well be the case that there is little
> point in supporting this mode as it's just a special case of fifo mode with
> the watermark set to 1.
I am short on time now, will have to do the fifo later.
>
> >
> > There are a few things in here that suggest this isn't tested as much
> > as I'd expect for a submission. If you are posting early, but need
> > to do more testing, please state that clearly.
> >
> > Jonathan
> >
> > > ---
> > > drivers/iio/accel/Kconfig | 4 ++
> > > drivers/iio/accel/adxl355.h | 2 +-
> > > drivers/iio/accel/adxl355_core.c | 102 ++++++++++++++++++++++++++++++-
> > > drivers/iio/accel/adxl355_i2c.c | 3 +-
> > > drivers/iio/accel/adxl355_spi.c | 2 +-
> > > 5 files changed, 108 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> > > index d0c45c809..9c16c1841 100644
> > > --- a/drivers/iio/accel/Kconfig
> > > +++ b/drivers/iio/accel/Kconfig
> > > @@ -69,6 +69,8 @@ config ADXL355_I2C
> > > depends on I2C
> > > select ADXL355
> > > select REGMAP_I2C
> > > + select IIO_BUFFER
> > > + select IIO_TRIGGERED_BUFFER
> > > help
> > > Say Y here if you want to build i2c support for the Analog Devices
> > > ADXL355 3-axis digital accelerometer.
> > > @@ -82,6 +84,8 @@ config ADXL355_SPI
> > > depends on SPI
> > > select ADXL355
> > > select REGMAP_SPI
> > > + select IIO_BUFFER
> > > + select IIO_TRIGGERED_BUFFER
> > > help
> > > Say Y here if you want to build spi support for the Analog Devices
> > > ADXL355 3-axis digital accelerometer.
> > > diff --git a/drivers/iio/accel/adxl355.h b/drivers/iio/accel/adxl355.h
> > > index 322b0abb8..f0a376e6d 100644
> > > --- a/drivers/iio/accel/adxl355.h
> > > +++ b/drivers/iio/accel/adxl355.h
> > > @@ -15,5 +15,5 @@ extern const struct regmap_access_table adxl355_readable_regs_tbl;
> > > extern const struct regmap_access_table adxl355_writeable_regs_tbl;
> > >
> > > int adxl355_core_probe(struct device *dev, struct regmap *regmap,
> > > - const char *name);
> > > + const char *name, int irq);
> > > #endif /* _ADXL355_H_ */
> > > diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
> > > index 47fbb31bc..f9dc2a530 100644
> > > --- a/drivers/iio/accel/adxl355_core.c
> > > +++ b/drivers/iio/accel/adxl355_core.c
> > > @@ -9,6 +9,10 @@
> > >
> > > #include <asm/unaligned.h>
> > > #include <linux/bitfield.h>
> > > +#include <linux/iio/buffer.h>
> > > +#include <linux/iio/trigger.h>
> > > +#include <linux/iio/triggered_buffer.h>
> > > +#include <linux/iio/trigger_consumer.h>
> > > #include <linux/iio/iio.h>
> > > #include <linux/limits.h>
> > > #include <linux/math64.h>
> > > @@ -172,6 +176,7 @@ static const struct adxl355_chan_info adxl355_chans[] = {
> > > };
> > >
> > > struct adxl355_data {
> > > + int irq;
> > > struct regmap *regmap;
> > > struct device *dev;
> > > struct mutex lock; /* lock to protect op_mode */
> > > @@ -181,6 +186,12 @@ struct adxl355_data {
> > > int calibbias[3];
> > > int adxl355_hpf_3db_table[7][2];
> > > u8 transf_buf[3] ____cacheline_aligned;
> > > + struct iio_trigger *dready_trig;
> > > + /* Ensure correct alignment of timestamp when present */
> > > + struct {
> > > + __be32 channels[3];
> > > + s64 ts;
> > > + } buffer ____cacheline_aligned;
> >
> > Interesting quirk here is that we need to ensure that any of the
> > buffers used for DMA don't share a cacheline with other data, but we don't
> > need to ensure they don't share with each other. As such, this can
> > share fine with transf_buf, but definitely not with dready_trig (which
> > can't share with transf_buf like it is right now).
> >
> > So reorder to put the various DMA safe buffers at the end, and ensure
> > the first one is cacheline aligned.
> >
> > Even better, given you can only safely access one at a time anyway
> > (and I think you always hold the lock so that is fine), put them in a union
> > to make it explicit that only one is used at a time.
> >
> > struct iio_trigger *dready_trig;
> > union {
> > u8 trans_buf[3];
> > struct {
> > __be32 channels[3];
> > s64 ts;
> > } buffer;
> > } ___cacheline_algned;
> > or something like that.
Thanks for suggesting this snippet, it works perfectly.
> >
> >
> >
> > > };
> > >
> > > static int adxl355_set_op_mode(struct adxl355_data *data,
> > > @@ -499,12 +510,46 @@ static int adxl355_read_avail(struct iio_dev *indio_dev,
> > > }
> > > }
> > >
> > > +static const unsigned long adxl355_avail_scan_masks[] = {
> > > + GENMASK(3, 0),
> > > + 0
> > > +};
> > > +
> > > static const struct iio_info adxl355_info = {
> > > .read_raw = adxl355_read_raw,
> > > .write_raw = adxl355_write_raw,
> > > .read_avail = &adxl355_read_avail
> > > };
> > >
> > > +static const struct iio_trigger_ops adxl355_trigger_ops = {
> > > + .validate_device = &iio_trigger_validate_own_device,
> >
> > No means of turning it on?
added a set state function.
> >
> > > +};
> > > +
> > > +static irqreturn_t adxl355_trigger_handler(int irq, void *p)
> > > +{
> > > + struct iio_poll_func *pf = p;
> > > + struct iio_dev *indio_dev = pf->indio_dev;
> > > + struct adxl355_data *data = iio_priv(indio_dev);
> > > + int ret;
> > > +
> > > + mutex_lock(&data->lock);
> > > +
> > > + ret = regmap_bulk_read(data->regmap, ADXL355_XDATA3_REG,
> > > + data->buffer.channels,
> > > + 9);
> >
> > That doesn't look right. you are reading 9 bytes into an array of 3 __be32 channels.
> > You should check the data is turning up where it should.
I have fixed this in the next version,
> >
> >
> > > + if (ret)
> > > + goto out_unlock_notify;
> > > +
> > > + iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer,
> > > + pf->timestamp);
> > > +
> > > +out_unlock_notify:
> > > + mutex_unlock(&data->lock);
> > > + iio_trigger_notify_done(indio_dev->trig);
> > > +
> > > + return IRQ_HANDLED;
> > > +}
> > > +
> > > #define ADXL355_ACCEL_CHANNEL(index, reg, axis) { \
> > > .type = IIO_ACCEL, \
> > > .address = reg, \
> > > @@ -518,6 +563,7 @@ static const struct iio_info adxl355_info = {
> > > .info_mask_shared_by_type_available = \
> > > BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> > > BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \
> > > + .scan_index = index, \
> > > .scan_type = { \
> > > .sign = 's', \
> > > .realbits = 20, \
> > > @@ -537,17 +583,56 @@ static const struct iio_chan_spec adxl355_channels[] = {
> > > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > > BIT(IIO_CHAN_INFO_SCALE) |
> > > BIT(IIO_CHAN_INFO_OFFSET),
> > > + .scan_index = 3,
> > > .scan_type = {
> > > .sign = 's',
> > > .realbits = 12,
> > > .storagebits = 16,
> > > .endianness = IIO_BE,
> > > },
> > > - }
> > > + },
> >
> > If you do end up respinning patch 2, add the comma in that patch as it'll reduced
> > noise here.
> >
> > > + IIO_CHAN_SOFT_TIMESTAMP(4)
> > > };
> > >
> > > +static int adxl355_probe_trigger(struct iio_dev *indio_dev)
> > > +{
> > > + struct adxl355_data *data = iio_priv(indio_dev);
> > > + int ret;
> > > +
> > > + if (!data->irq) {
> > > + dev_info(data->dev, "no irq, using polling\n");
> > > + return 0;
> > > + }
> > > +
> > > + data->dready_trig = devm_iio_trigger_alloc(data->dev, "%s-dev%d",
> > > + indio_dev->name,
> > > + indio_dev->id);
> > > + if (!data->dready_trig)
> > > + return -ENOMEM;
> > > +
> > > + data->dready_trig->ops = &adxl355_trigger_ops;
> > > + iio_trigger_set_drvdata(data->dready_trig, indio_dev);
> > > +
> > > + ret = devm_request_irq(data->dev, data->irq,
> > > + &iio_trigger_generic_data_rdy_poll,
> > > + IRQF_ONESHOT, "adxl355_irq", data->dready_trig);
> > > + if (ret < 0)
> > > + return dev_err_probe(data->dev, ret, "request irq %d failed\n",
> > > + data->irq);
> > > +
> > > + ret = devm_iio_trigger_register(data->dev, data->dready_trig);
> > > + if (ret) {
> > > + dev_err(data->dev, "iio trigger register failed\n");
> > > + return ret;
> > > + }
> > > +
> > > + indio_dev->trig = iio_trigger_get(data->dready_trig);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > int adxl355_core_probe(struct device *dev, struct regmap *regmap,
> > > - const char *name)
> > > + const char *name, int irq)
> > > {
> > > struct adxl355_data *data;
> > > struct iio_dev *indio_dev;
> > > @@ -560,6 +645,7 @@ int adxl355_core_probe(struct device *dev, struct regmap *regmap,
> > > data = iio_priv(indio_dev);
> > > data->regmap = regmap;
> > > data->dev = dev;
> > > + data->irq = irq;
> > > data->op_mode = ADXL355_STANDBY;
> > > mutex_init(&data->lock);
> > >
> > > @@ -568,6 +654,7 @@ int adxl355_core_probe(struct device *dev, struct regmap *regmap,
> > > indio_dev->modes = INDIO_DIRECT_MODE;
> > > indio_dev->channels = adxl355_channels;
> > > indio_dev->num_channels = ARRAY_SIZE(adxl355_channels);
> > > + indio_dev->available_scan_masks = adxl355_avail_scan_masks;
> > >
> > > ret = adxl355_setup(data);
> > > if (ret < 0) {
> > > @@ -575,6 +662,17 @@ int adxl355_core_probe(struct device *dev, struct regmap *regmap,
> > > return ret;
> > > }
> > >
> > > + ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
> > > + &iio_pollfunc_store_time,
> > > + &adxl355_trigger_handler, NULL);
> > > + if (ret < 0)
> >
> > if (ret) preferred, because it is more consistent with returning devm_iio_device_register()
> > below (where we are assuming negative or 0 only)
> >
> > > + return dev_err_probe(dev, ret,
> > > + "iio triggered buffer setup failed\n");
> > > +
> > > + ret = adxl355_probe_trigger(indio_dev);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > return devm_iio_device_register(dev, indio_dev);
> > > }
> > > EXPORT_SYMBOL_GPL(adxl355_core_probe);
> > > diff --git a/drivers/iio/accel/adxl355_i2c.c b/drivers/iio/accel/adxl355_i2c.c
> > > index e3070ee81..c18521819 100644
> > > --- a/drivers/iio/accel/adxl355_i2c.c
> > > +++ b/drivers/iio/accel/adxl355_i2c.c
> > > @@ -31,7 +31,8 @@ static int adxl355_i2c_probe(struct i2c_client *client)
> > > return PTR_ERR(regmap);
> > > }
> > >
> > > - return adxl355_core_probe(&client->dev, regmap, client->name);
> > > + return adxl355_core_probe(&client->dev, regmap, client->name,
> > > + client->irq);
> >
> > We can't just use the first interrupt (which this corresponds to) because
> > the device supports 3 and who knows if this is the right one?
> >
> > Now to solve this, we run into a 'fun' issue. We want to use the generic
> > firmware property interfaces (include/linux/property.h) but that doesn't
> > include a fwnode_irq_get_by_name()
> >
> > We've had some recent discussion about this:
> > https://lore.kernel.org/linux-iio/20210724190614.3593dcd1@jic23-huawei/
> >
> > If it is something you would like to take on, that would be great.
> > If not, for now use the of_irq_get_byname() method but add a comment
> > saying it would good to move to a generic version.
I really want to work on fwnode_irq_get_by_name() but I am short on
time, I will work on it next month.
this would be a nice project for me, btw.
> >
> > > }
> > >
> > > static const struct i2c_device_id adxl355_i2c_id[] = {
> > > diff --git a/drivers/iio/accel/adxl355_spi.c b/drivers/iio/accel/adxl355_spi.c
> > > index a16bd1407..f9ba153f6 100644
> > > --- a/drivers/iio/accel/adxl355_spi.c
> > > +++ b/drivers/iio/accel/adxl355_spi.c
> > > @@ -34,7 +34,7 @@ static int adxl355_spi_probe(struct spi_device *spi)
> > > return PTR_ERR(regmap);
> > > }
> > >
> > > - return adxl355_core_probe(&spi->dev, regmap, id->name);
> > > + return adxl355_core_probe(&spi->dev, regmap, id->name, spi->irq);
> > > }
> > >
> > > static const struct spi_device_id adxl355_spi_id[] = {
> >
>
--
Thanks and Regards
Yours Truly,
Puranjay Mohan