mpm/mpmd: Expose APIs to drive GPIO sources

The N310 has a feature that allows the front panel GPIOs to be driven by
various sources: The PS, or any of the radio channels. The MPM-based
APIs did not expose any way to change that.

Changes:
- Add MPM APIs to PeripheralManagerBase and n3xx classes
- Improve comments and explanations
- Add host-side hooks into these new APIs in mpmd_mb_controller
- Implement these APIs for N3xx

The N3xx devices will have the option to set the GPIO source to "PS", or
to one of "RF0", "RF1", "RF2", "RF3" (if there are four channels; the
N300 and N320 can only go up to RF1).

Note: The N310 radio does not have separate FP-GPIO banks for channels
0 and 1, which needs to be fixed in a separate commit.

1 files changed, 3 insertions, 1 deletions

diff --git a/mpm/python/usrp_mpm/bist.py b/mpm/python/usrp_mpm/bist.py
index e26d6d36c..b20020e1f 100644
--- a/mpm/python/usrp_mpm/bist.py
+++ b/mpm/python/usrp_mpm/bist.py
@@ -246,7 +246,9 @@ def get_tpm_caps_info():
     return result
 
 def gpio_set_all(gpio_bank, value, gpio_size, ddr_mask):
-    """Helper function for set gpio.
+    """
+    Helper function to set GPIOs
+
     What this function do is take decimal value and convert to a binary string
     then try to set those individual bits to the gpio_bank.
     Arguments: