[PATCH v2 3/4] staging: iio: ad5933: add ABI documentation

[Marcelo Schmitt <marcelo.schmitt1@gmail.com>]

Add an ABI documentation for the ad5933 driver.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
---
 .../ABI/testing/sysfs-bus-iio-ad5933          | 91 +++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-ad5933

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-ad5933 b/Documentation/ABI/testing/sysfs-bus-iio-ad5933
new file mode 100644
index 000000000000..81e3d3f6f724
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-ad5933
@@ -0,0 +1,91 @@
+What:/sys/bus/iio/devices/iio:deviceX/out_voltage0_scale
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The output peak-to-peak voltage range. Writting 0 sets range
+		to 2.0V p-p typical, 1 sets range to 200mV p-p typical, 2 sets
+		range to 400mV p-p typical, 3 sets range to 1.0V p-p typical.
+		The p-p value of the ac output exitation voltage scales with 
+		supply voltage according to the following formula:
+		Output Excitation Voltage (V p-p) = normalized_3v3 × [VDD/3.3]
+		where normalized_3v3 is one of the four voltage range above and
+		VDD is the supply voltage.
+
+What:/sys/bus/iio/devices/iio:deviceX/out_voltage0_scale_available
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:	
+		Prints available peak-to-peak voltage range to buffer.
+
+What:/sys/bus/iio/devices/iio:deviceX/out_voltage0_freq_start
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The start frequency. Set this to define de frequency point at
+		which the device should start the next frequency sweep. Default
+		start frequency point set to 10000Hz.
+
+What:/sys/bus/iio/devices/iio:deviceX/out_voltage0_freq_increment
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The frequency sweep increment. Set this to define at which rate
+		frequency sweep points are incremented. After the measurement at
+		a frequency point is completed, the next measurement will be 
+		made with a frequency 'frequency increment'Hz higher than the
+		previous point until the defined number of increments has been
+		made. Default frequency increment set to 200Hz.
+		
+
+What:/sys/bus/iio/devices/iio:deviceX/out_voltage0_freq_points
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The number of increments. This defines the number of frequency
+		points in the frequency sweep. Device stores a 9-bit integer
+		number in binary format for this so the maximum number of
+		increments that can be programmed is 511.
+
+What:/sys/bus/iio/devices/iio:deviceX/out_voltage0_settling_cycles
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Number of settling time cycles. This attribute is a 11 bit field
+		divided in two parts. The 9 least significant bit define the
+		number of output excitation cycles that are passed through the
+		unknown impedance, after the receipt of a start frequency sweep,
+		increment frequency, or repeat frequency command, before the ADC
+		is triggered to perform a conversion of the response signal. The
+		2 most significant bits define a multiplier for the number of
+		cycles obtained from de least significant bits. Let D10 and D9
+		be these two bits, the resulting multiplier is defined as
+		follows.
+		D10 D9 = 0 0 => No. of cycles x 1 (default)
+		D10 D9 = 0 1 => No. of cycles x 2
+		D10 D9 = 1 0 => Reserved
+		D10 D9 = 1 1 => No. of cycles x 4
+
+		See the datasheet for detailed information.
+
+What:/sys/bus/iio/devices/iio:deviceX/in_voltage0_scale
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The PGA gain amplifier for the response signal. Set this to 0
+		to gain the output of the current-to-voltage amplifier by a
+		factor of 5. Set to 1 (default) to amplify the response signal
+		into the ADC by a multiplication factor of x1.
+
+What:/sys/bus/iio/devices/iio:deviceX/in_voltage0_scale_available
+Date:		February 2019
+KernelVersion:	Kernel 4.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Prints available PGA gain amplifier to buffer.
-- 
2.20.1