bladerf: implement options for clock configuration

Since firmware 2016.01-rc1 bladeRF has the ability to lock to an
external reference as well as produce arbitrary frequency signal
(25 MHz here) on its clock output.

Use gr-osmosdr source with the following arguments to produce 25
MHz on the SMB connector:

osmocom_fft -a bladerf,smb=25e6

smb=25e6

To lock the bladeRF itself to an external GPSDO reference, use
additional arguments tamer=external for 10MHz or tamer=external_1pps for
1PPS GPSDO signals.

osmocom_fft -a bladerf,smb=25e6,tamer=external

tamer={internal,external_1pps,external}

The described method requires https://github.com/Nuand/bladeRF/releases/
tag/2016.01-rc1

Carefully *read the instructions for external reference locking*
(especially max allowed voltage levels) on Nuand's blog https://
www.nuand.com/blog/2016-01-rc1-release/

1 files changed, 15 insertions, 0 deletions

diff --git a/lib/bladerf/bladerf_source_c.cc b/lib/bladerf/bladerf_source_c.cc
index b4afcb2..ac002db 100644
--- a/lib/bladerf/bladerf_source_c.cc
+++ b/lib/bladerf/bladerf_source_c.cc
@@ -537,3 +537,18 @@ osmosdr::freq_range_t bladerf_source_c::get_bandwidth_range( size_t chan )
 {
   return filter_bandwidths();
 }
+
+void bladerf_source_c::set_clock_source(const std::string &source, const size_t mboard)
+{
+  bladerf_common::set_clock_source(source, mboard);
+}
+
+std::string bladerf_source_c::get_clock_source(const size_t mboard)
+{
+  return bladerf_common::get_clock_source(mboard);
+}
+
+std::vector<std::string> bladerf_source_c::get_clock_sources(const size_t mboard)
+{
+  return bladerf_common::get_clock_sources(mboard);
+}