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/periph_manager/n3xx_periphs.py b/mpm/python/usrp_mpm/periph_manager/n3xx_periphs.py
index ef2372e62..bcff03c8e 100644
--- a/mpm/python/usrp_mpm/periph_manager/n3xx_periphs.py
+++ b/mpm/python/usrp_mpm/periph_manager/n3xx_periphs.py
@@ -195,6 +195,8 @@ class MboardRegsControl(MboardRegsCommon):
         """set driver for front panel GPIO
         Arguments:
             value {unsigned} -- value is a single bit bit mask of 12 pins GPIO
+           0: means the pin is driven by PL
+           1: means the pin is driven by PS
         """
         with self.regs:
             return self.poke32(self.MB_GPIO_MASTER, value)
@@ -211,7 +213,7 @@ class MboardRegsControl(MboardRegsCommon):
     def set_fp_gpio_radio_src(self, value):
         """set driver for front panel GPIO
         Arguments:
-            value {unsigned} -- value is 2-bit bit mask of 12 pins GPIO
+            value {unsigned} -- value is 2x12 bits, two bits per GPIO pin
            00: means the pin is driven by radio 0
            01: means the pin is driven by radio 1
            10: means the pin is driven by radio 2