iio: frequency: New driver for Analog Devices ADF4350/ADF4351 Wideband Synthesizers

Changes since V1:
Apply Jonathan's review feedback:
    Introduce and use IIO_ALTVOLTAGE.
    Fix up comments and documentation.
    Remove dead code.
    Reorder some code fragments.
    Add missing iio_device_free.

Convert to new API.
Fix-up out of staging includes.
Removed pll_locked attribute.

Changes since V2:
Use module_spi_driver.
adf4350_remove: move gpio_free after regulator.
target patch to drivers/iio

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-frequency-adf4350 b/Documentation/ABI/testing/sysfs-bus-iio-frequency-adf4350
new file mode 100644
index 000000000000..d89aded01c5a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-frequency-adf4350
@@ -0,0 +1,21 @@
+What:           /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_frequency_resolution
+KernelVersion:  3.4.0
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Stores channel Y frequency resolution/channel spacing in Hz.
+                The value given directly influences the MODULUS used by
+                the fractional-N PLL. It is assumed that the algorithm
+                that is used to compute the various dividers, is able to
+                generate proper values for multiples of channel spacing.
+
+What:           /sys/bus/iio/devices/iio:deviceX/out_altvoltageY_refin_frequency
+KernelVersion:  3.4.0
+Contact:        linux-iio@vger.kernel.org
+Description:
+                Sets channel Y REFin frequency in Hz. In some clock chained
+                applications, the reference frequency used by the PLL may
+                change during runtime. This attribute allows the user to
+                adjust the reference frequency accordingly.
+                The value written has no effect until out_altvoltageY_frequency
+                is updated. Consider to use out_altvoltageY_powerdown to power
+                down the PLL and it's RFOut buffers during REFin changes.