From: Marcelo Schmitt Date: Thu, 27 Mar 2025 21:25:12 +0000 (-0300) Subject: Documentation: iio: ad4000: Add IIO Device characteristics section X-Git-Tag: v6.16-rc1~30^2~4^2~165 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=d66b2c84fb675b6ac2ffe285bf447b18badf6e4b;p=linux-block.git Documentation: iio: ad4000: Add IIO Device characteristics section Complement ad4000 IIO driver documentation with considerations about ``_scale_available`` attribute and table of typical channel attributes. Reviewed-by: David Lechner Signed-off-by: Marcelo Schmitt Link: https://patch.msgid.link/6c8fe68d7d413ffdd33b154ba45600c7ce7013da.1743110188.git.marcelo.schmitt@analog.com Signed-off-by: Jonathan Cameron --- diff --git a/Documentation/iio/ad4000.rst b/Documentation/iio/ad4000.rst index 5578a9cfd9d5..468d30dc9214 100644 --- a/Documentation/iio/ad4000.rst +++ b/Documentation/iio/ad4000.rst @@ -144,3 +144,50 @@ Set ``adi,sdi-pin`` to ``"cs"`` to select this mode. ^ | | +--------------------| SCLK | +-------------+ + +IIO Device characteristics +========================== + +The AD4000 series driver supports differential and pseudo-differential ADCs. + +The span compression feature available in AD4000 series devices can be +enabled/disabled by changing the ``_scale_available`` attribute of the voltage +channel. Note that span compression configuration requires writing to AD4000 +configuration register, which is only possible when the ADC is wired in 3-wire +turbo mode, and the SPI controller is ``SPI_MOSI_IDLE_HIGH`` capable. If those +conditions are not met, no ``_scale_available`` attribute is provided. + +Besides that, differential and pseudo-differential voltage channels present +slightly different sysfs interfaces. + +Pseudo-differential ADCs +------------------------ + +Typical voltage channel attributes of a pseudo-differential AD4000 series device: + ++-------------------------------------------+------------------------------------------+ +| Voltage Channel Attributes | Description | ++===========================================+==========================================+ +| ``in_voltage0_raw`` | Raw ADC output code. | ++-------------------------------------------+------------------------------------------+ +| ``in_voltage0_offset`` | Offset to convert raw value to mV. | ++-------------------------------------------+------------------------------------------+ +| ``in_voltage0_scale`` | Scale factor to convert raw value to mV. | ++-------------------------------------------+------------------------------------------+ +| ``in_voltage0_scale_available`` | Toggles input span compression | ++-------------------------------------------+------------------------------------------+ + +Differential ADCs +----------------- + +Typical voltage channel attributes of a differential AD4000 series device: + ++-------------------------------------------+------------------------------------------+ +| Voltage Channel Attributes | Description | ++===========================================+==========================================+ +| ``in_voltage0-voltage1_raw`` | Raw ADC output code. | ++-------------------------------------------+------------------------------------------+ +| ``in_voltage0-voltage1_scale`` | Scale factor to convert raw value to mV. | ++-------------------------------------------+------------------------------------------+ +| ``in_voltage0-voltage1_scale_available`` | Toggles input span compression | ++-------------------------------------------+------------------------------------------+