This driver supports 14-bits and 16-bits devices. All of them have a 14-bit
configuration registers. All SPI trasfers, for reading AD conversion
results and for writing the configuration register, fit in two bytes.
The driver always uses 4-bytes xfers which seems at least pointless (maybe
even harmful). This patch trims the SPI xfer len and the buffer size to
two bytes.
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The device could be configured to spit out also the configuration word
while reading the AD result value (in the same SPI xfer) - this is called
"readback" in the device datasheet.
The driver checks if readback is enabled and it eventually adjusts the SPI
xfer length and it applies proper shifts to still get the data, discarding
the configuration word.
The readback option is actually never enabled (the driver disables it), so
the said checks do not serve for any purpose.
Since enabling the readback option seems not to provide any advantage (the
driver entirely sets the configuration word without relying on any default
value), just kill the said, unused, code.
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Compatible with AD7682 and AD7689 chips.
It is a Analog Devices ADC driver 14/16 bits 4/8 channels
with SPI protocol
Datasheet of the device:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD7949.pdf
Signed-off-by: Charles-Antoine Couret <charles-antoine.couret@essensium.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
