Add burst_max_len to `adis_burst`. This is useful for devices which
support different burst modes with different sizes. The buffer to be
used in the spi transfer is allocated with this variable making sure
that has space for all burst modes. The spi transfer length should hold
the "real" burst length depending on the current burst mode configured
in the device.

Moreover, `extra_len` in `adis_burst` is made const and it should
contain the smallest extra length necessary for a burst transfer. In
`struct adis` was added a new `burst_extra_len` that should hold the
extra bytes needed depending on the device instance being used.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This patch adds a `regmap_update_bits()` like API to the ADIS library.
It provides locked and unlocked variant.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

There are some ADIS devices that can configure the data ready pin
polarity. Hence, we cannot hardcode our IRQ mask as IRQF_TRIGGER_RISING
since we might want to have it as IRQF_TRIGGER_FALLING.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This patch adds support for a managed device version of
adis_setup_buffer_and_trigger. It works exactly as the original
one but it calls all the devm_iio_* functions to setup an iio
buffer and trigger. Hence we do not need to care about cleaning those
and we do not need to support a remove() callback for every driver using
the adis library.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

The 'state_lock' mutex was renamed from 'txrx_lock' in a previous patch and
is intended to be used by ADIS drivers to protect the state of devices
during consecutive R/W ops.
The initial patch that introduced this change did not do a good [well, any]
job at explaining this. This patch adds a comment to the 'state_lock'
better explaining it's use.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

The doc-string has been neglected over time.
This change updates it with all the missing info.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This change adds a doc-string for the 'adis' struct. It details the fields
and their roles.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Each driver/chip that wants to validate it's product id, can now
specify a 'prod_id_reg' and an expected 'prod_id' value.
The 'prod_id' value is intentionally left 0 (uninitialized). There aren't
(yet) any product IDs with value 0; this enforces that both 'prod_id_reg'
and 'prod_id' are specified.

At the very least, this routine validates that the SPI connection to the
ADIS chip[s] works well.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This patch adds a dedicated self_test_reg variable. This is also a step
to let new drivers make use of `adis_initial_startup()`. Some devices
use MSG_CTRL reg to request a self_test command while others use the
GLOB_CMD register.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

This change splits the __adis_initial_startup() away from
adis_initial_startup(). The unlocked version can be used in certain calls
during probe, where races won't happen since the ADIS driver may not be
registered yet with IIO.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>