Using (pci) device id to identify the ASIC on sai_switch_create (#4705)

* Update to sonic_cfggen and utilities to populate the (pci) device id in the "asic_id" field in the DEVICE_METADATA. This Id is parsed from the file "asic.conf" file in the device/<platform> dir. The format of entries are  eg:  for a 2 ASIC platform.
DEV_ID_ASIC_0=03:00.0
DEV_ID_ASIC_1=04:00.0
 
Going forward will use this device id as the asic instance ID passed to syncd/sai while doing create_switch. Current support is limited, supports only one TD2 platform.

src/sonic-config-engine/sonic-cfggen

@@ -43,6 +43,7 @@ from sonic_device_util import get_machine_info
 from sonic_device_util import get_platform_info
 from sonic_device_util import get_system_mac
 from sonic_device_util import get_npu_id_from_name
+from sonic_device_util import get_npu_device_id
 from config_samples import generate_sample_config
 from config_samples import get_available_config
 from swsssdk import SonicV2Connector, ConfigDBConnector, SonicDBConfig 
@@ -304,7 +305,12 @@ def main():
             }}}
         # The ID needs to be passed to the SAI to identify the asic.
         if asic_name is not None:
-            hardware_data['DEVICE_METADATA']['localhost'].update(asic_id=asic_id)
+            device_id = get_npu_device_id(asic_id)
+            # if the device_id obtained is None, exit with error
+            if device_id is None:
+                print('Failed to get device ID for', asic_name, file=sys.stderr)
+                sys.exit(1)
+            hardware_data['DEVICE_METADATA']['localhost'].update(asic_id=device_id)
         deep_update(data, hardware_data)
 
     if args.template is not None:

src/sonic-config-engine/sonic_device_util.py

@@ -44,6 +44,32 @@ def get_npu_id_from_name(npu_name):
     else:
         return None
 
+def get_npu_device_id(npu_id):
+    platform = get_platform_info(get_machine_info())
+    if not platform:
+        return None
+
+    asic_conf_file_path = os.path.join(SONIC_DEVICE_PATH, platform, ASIC_CONF_FILENAME)
+    if not os.path.isfile(asic_conf_file_path):
+        return None
+
+    # In a multi-npu device we need to have the file "asic.conf" updated with the asic instance
+    # and the corresponding device id which could be pci_id. Below is an eg: for a 2 ASIC platform/sku.
+    # DEV_ID_ASIC_0=03:00.0
+    # DEV_ID_ASIC_1=04:00.0
+    device_str = "DEV_ID_ASIC_{}".format(npu_id)
+
+    with open(asic_conf_file_path) as asic_conf_file:
+        for line in asic_conf_file:
+            tokens = line.split('=')
+            if len(tokens) < 2:
+               continue
+            if tokens[0] == device_str:
+                device_id = tokens[1].strip()
+                return device_id
+
+    return None
+
 def get_num_npus():
     platform = get_platform_info(get_machine_info())
     if not platform: