mpm: Add i2c_dev lookup using sys_name

Add i2c_dev adapter device lookup which uses a the sys_name value
instead of OF_NAME to find the adapter. OF_NAME is not unique for some
i2c device nodes. The logic for finding the adapter from the parent
node was pulled into a helper function and is shared across both
lookup functions.

Co-authored-by: Michael Auchter <michael.auchter@ni.com>
Co-authored-by: Toni Jones <toni.jones@ni.com>

1 files changed, 51 insertions, 7 deletions

diff --git a/mpm/python/usrp_mpm/sys_utils/i2c_dev.py b/mpm/python/usrp_mpm/sys_utils/i2c_dev.py
index 7da5177f8..b84086e55 100644
--- a/mpm/python/usrp_mpm/sys_utils/i2c_dev.py
+++ b/mpm/python/usrp_mpm/sys_utils/i2c_dev.py
@@ -8,6 +8,21 @@ Utilities for i2c lookups
 """
 
 import pyudev
+from usrp_mpm.sys_utils.udev import get_device_from_dt_symbol
+
+def _get_i2c_adapter_from_parent(parent, context):
+    """
+    Helper to get the i2c adapter from a given parent device.
+    This logic is common for different device lookup methods.
+    """
+    if not parent:
+        return None
+    devices = list(context.list_devices(parent=parent, subsystem="i2c-dev"))
+    properties = [dict(d.properties) for d in devices]
+    # The i2c-adapter will have the lowest minor number
+    # FIXME: This likely isn't API--It just happens to work as of this writing
+    chosen = min([(int(p['MINOR']), p['DEVNAME']) for p in properties])
+    return chosen[1]
 
 def of_get_i2c_adapter(of_name):
     """
@@ -26,11 +41,40 @@ def of_get_i2c_adapter(of_name):
     if len(parents) == 0:
         return None
     parent = parents[0]
-    if not parent:
+    return _get_i2c_adapter_from_parent(parent, context)
+
+
+def dt_symbol_get_i2c_bus(symbol):
+    """
+    Return i2c bus associated with the given device tree symbol
+
+    The return value is a string, e.g. '/dev/i2c-0'. If nothing is found, it'll
+    return None.
+    """
+    context = pyudev.Context()
+    parent = get_device_from_dt_symbol(symbol, subsystem='i2c', context=context)
+    return _get_i2c_adapter_from_parent(parent, context)
+
+
+def sysname_get_i2c_adapter(sys_name):
+    """
+    Return bus adapter device for given device tree sys_name.
+
+    The return value is a string, e.g. '/dev/i2c-0'. If nothing is found, it'll
+    return None.
+    """
+    parent = sysname_get_i2c_parent(sys_name)
+    return _get_i2c_adapter_from_parent(parent, pyudev.Context())
+
+def sysname_get_i2c_parent(sys_name):
+    """
+    Returns the parent of an i2c adapter found by sys_name
+    """
+    # If has i2c-dev, follow to grab i2c-%d node
+    context = pyudev.Context()
+    parents = list(context.list_devices(subsystem="i2c-adapter", sys_name=sys_name))
+    if len(parents) > 1:
+        raise RuntimeError("Non-unique sys_name when getting i2c bus id")
+    if len(parents) == 0:
         return None
-    devices = list(context.list_devices(parent=parent, subsystem="i2c-dev"))
-    properties = [dict(d.properties) for d in devices]
-    # The i2c-adapter will have the lowest minor number
-    # FIXME: This likely isn't API--It just happens to work as of this writing
-    chosen = min([(int(p['MINOR']), p['DEVNAME']) for p in properties])
-    return chosen[1]
+    return parents[0]