Staging: IIO: Direct digital synthesis abi documentation

Changes since RFC/v1:
IIO: Apply list review feedback:

Apply list review feedback:
	Restructure documentation according to list feedback.
	Rename attributes to fit IIO convention used in other drivers.
	Fix typos.
	Provide ddsX_out_enable as opposed to ddsX_out_disable

Changes since v2:
IIO: sysfs-bus-iio-dds: Apply more list review feedback

	Fix mixture of X and [n] notation for indices.
	Fix some wording in the descriptions.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 93 insertions, 0 deletions

diff --git a/drivers/staging/iio/Documentation/sysfs-bus-iio-dds b/drivers/staging/iio/Documentation/sysfs-bus-iio-dds
new file mode 100644
index 00000000000..ffdd5478a35
--- /dev/null
+++ b/drivers/staging/iio/Documentation/sysfs-bus-iio-dds
@@ -0,0 +1,93 @@
+
+What:           /sys/bus/iio/devices/.../ddsX_freqY
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Stores frequency into tuning word Y.
+                There will be more than one ddsX_freqY file, which allows for
+                pin controlled FSK Frequency Shift Keying
+                (ddsX_pincontrol_freq_en is active) or the user can control
+                the desired active tuning word by writing Y to the
+                ddsX_freqsymbol file.
+
+What:           /sys/bus/iio/devices/.../ddsX_freqY_scale
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Scale to be applied to ddsX_freqY in order to obtain the
+                desired value in Hz. If shared across all frequency registers
+                Y is not present. It is also possible X is not present if
+                shared across all channels.
+
+What:           /sys/bus/iio/devices/.../ddsX_freqsymbol
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Specifies the active output frequency tuning word. The value
+                corresponds to the Y in ddsX_freqY. To exit this mode the user
+                can write ddsX_pincontrol_freq_en or ddsX_out_enable file.
+
+What:           /sys/bus/iio/devices/.../ddsX_phaseY
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Stores phase into Y.
+                There will be more than one ddsX_phaseY file, which allows for
+                pin controlled PSK Phase Shift Keying
+                (ddsX_pincontrol_phase_en is active) or the user can
+                control the desired phase Y which is added to the phase
+                accumulator output by writing Y to the en_phase file.
+
+What:           /sys/bus/iio/devices/.../ddsX_phaseY_scale
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Scale to be applied to ddsX_phaseY in order to obtain the
+                desired value in rad. If shared across all phase registers
+                Y is not present. It is also possible X is not present if
+                shared across all channels.
+
+What:           /sys/bus/iio/devices/.../ddsX_phasesymbol
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Specifies the active phase Y which is added to the phase
+                accumulator output. The value corresponds to the Y in
+                ddsX_phaseY. To exit this mode the user can write
+                ddsX_pincontrol_phase_en or disable file.
+
+What:           /sys/bus/iio/devices/.../ddsX_pincontrol_en
+What:           /sys/bus/iio/devices/.../ddsX_pincontrol_freq_en
+What:           /sys/bus/iio/devices/.../ddsX_pincontrol_phase_en
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                ddsX_pincontrol_en: Both, the active frequency and phase is
+                controlled by the respective phase and frequency control inputs.
+                In case the device in question allows to independent controls,
+                then there are dedicated files (ddsX_pincontrol_freq_en,
+                ddsX_pincontrol_phase_en).
+
+What:           /sys/bus/iio/devices/.../ddsX_out_enable
+What:           /sys/bus/iio/devices/.../ddsX_outY_enable
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                ddsX_outY_enable controls signal generation on output Y of
+                channel X. Y may be suppressed if all channels are
+                controlled together.
+
+What:           /sys/bus/iio/devices/.../ddsX_outY_wavetype
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Specifies the output waveform.
+                (sine, triangle, ramp, square, ...)
+                For a list of available output waveform options read
+                available_output_modes.
+
+What:           /sys/bus/iio/devices/.../ddsX_outY_wavetype_available
+KernelVersion:  2.6.37
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Lists all available output waveform options.