[DELL][S6000] Platform 2.0 TransceiverChange Support (#3414)

Implemented remaining APIs in s6100,z9100,s6000
Removed soft link in s6100,s6000,z9100 and implemented seperately
Implemented get_transceiver_change_event in S6000

platform/broadcom/sonic-platform-modules-dell/s6000/sonic_platform/chassis.py

@@ -9,6 +9,8 @@
 
 try:
     import os
+    import time
+    import datetime
     from sonic_platform_base.chassis_base import ChassisBase
     from sonic_platform.sfp import Sfp
 except ImportError as e:
@@ -22,29 +24,36 @@ class Chassis(ChassisBase):
 
     MAILBOX_DIR = "/sys/devices/platform/dell-s6000-cpld.0"
 
+    sfp_control = ""
+    PORT_START = 0
+    PORT_END = 0
     reset_reason_dict = {}
     reset_reason_dict[0xe] = ChassisBase.REBOOT_CAUSE_NON_HARDWARE
     reset_reason_dict[0x6] = ChassisBase.REBOOT_CAUSE_NON_HARDWARE
 
     def __init__(self):
         # Initialize SFP list
-        PORT_START = 0
-        PORT_END = 31
+        self.PORT_START = 0
+        self.PORT_END = 31
         EEPROM_OFFSET = 20
-        PORTS_IN_BLOCK = (PORT_END + 1)
+        PORTS_IN_BLOCK = (self.PORT_END + 1)
 
         # sfp.py will read eeprom contents and retrive the eeprom data.
         # It will also provide support sfp controls like reset and setting
         # low power mode.
         # We pass the eeprom path and sfp control path from chassis.py
         # So that sfp.py implementation can be generic to all platforms
         eeprom_base = "/sys/class/i2c-adapter/i2c-{0}/{0}-0050/eeprom"
-        sfp_control = "/sys/devices/platform/dell-s6000-cpld.0/"
+        self.sfp_control = "/sys/devices/platform/dell-s6000-cpld.0/"
+
         for index in range(0, PORTS_IN_BLOCK):
             eeprom_path = eeprom_base.format(index + EEPROM_OFFSET)
-            sfp_node = Sfp(index, 'QSFP', eeprom_path, sfp_control, index)
+            sfp_node = Sfp(index, 'QSFP', eeprom_path, self.sfp_control, index)
             self._sfp_list.append(sfp_node)
 
+        # Get Transceiver status
+        self.modprs_register = self._get_transceiver_status()
+
     def get_register(self, reg_name):
         rv = 'ERR'
         mb_reg_file = self.MAILBOX_DIR+'/'+reg_name
@@ -76,3 +85,69 @@ def get_reboot_cause(self):
 
         return (ChassisBase.REBOOT_CAUSE_HARDWARE_OTHER, "Invalid Reason")
 
+    def _get_transceiver_status(self):
+        presence_ctrl = self.sfp_control + 'qsfp_modprs'
+        try:
+            reg_file = open(presence_ctrl)
+
+        except IOError as e:
+            return False
+
+        content = reg_file.readline().rstrip()
+        reg_file.close()
+
+        return int(content, 16)
+
+    def get_transceiver_change_event(self, timeout=0):
+        """
+        Returns a dictionary containing sfp changes which have
+        experienced a change at chassis level
+        """
+        start_time = time.time()
+        port_dict = {}
+        port = self.PORT_START
+        forever = False
+
+        if timeout == 0:
+            forever = True
+        elif timeout > 0:
+            timeout = timeout / float(1000) # Convert to secs
+        else:
+            return False, {}
+        end_time = start_time + timeout
+
+        if (start_time > end_time):
+            return False, {} # Time wrap or possibly incorrect timeout
+
+        while (timeout >= 0):
+            # Check for OIR events and return updated port_dict
+            reg_value = self._get_transceiver_status()
+            if (reg_value != self.modprs_register):
+                changed_ports = (self.modprs_register ^ reg_value)
+                while (port >= self.PORT_START and port <= self.PORT_END):
+                    # Mask off the bit corresponding to our port
+                    mask = (1 << port)
+                    if (changed_ports & mask):
+                        # ModPrsL is active low
+                        if reg_value & mask == 0:
+                            port_dict[port] = '1'
+                        else:
+                            port_dict[port] = '0'
+                    port += 1
+
+                # Update reg value
+                self.modprs_register = reg_value
+                return True, port_dict
+
+            if forever:
+                time.sleep(1)
+            else:
+                timeout = end_time - time.time()
+                if timeout >= 1:
+                    time.sleep(1) # We poll at 1 second granularity
+                else:
+                    if timeout > 0:
+                        time.sleep(timeout)
+                    return True, {}
+        return False, {}
+