Dell S6000: Fix reboot failure issue (#6656)

Reboot command in Dell S6000 failed to reboot the switch. Added retry mechanism and CPU reset.

device/dell/x86_64-dell_s6000_s1220-r0/platform_reboot

@@ -4,10 +4,11 @@ import sys
 import os
 import struct
 
+PORT_RES = '/dev/port'
 NVRAM_RES = '/dev/nvram'
 COLD_RESET = 0xE     # Cold Reset
 WARM_RESET = 0x6     # Warm Reset
-
+RESET_REG = 0xCF9
 
 def io_reg_write(resource, offset, val):
     fd = os.open(resource, os.O_RDWR)
@@ -23,39 +24,40 @@ def io_reg_write(resource, offset, val):
         return
     os.close(fd)
 
-
 def power_reset(val):
     with open('/sys/devices/platform/dell-s6000-cpld.0/power_reset', 'w') as p:
         p.write(str(int(val)) + '\n')
         p.flush()
 
-
 def gpio_direction(pin, direction):
     kernpath = '/sys/class/gpio/gpio'+str(pin)+'/direction'
     with open(('kernpath'), 'w') as p:
         p.write(str(direction) + '\n')
         p.flush()
 
-
 def gpio_set(pin, value):
     kernpath = '/sys/class/gpio/gpio'+str(pin)+'/value'
     with open(('kernpath'), 'w') as p:
         p.write(str(int(value)) + '\n')
         p.flush()
 
-
 def gpio_export(value):
     with open('/sys/class/gpio/export', 'w') as p:
         p.write(str(int(value)) + '\n')
         p.flush()
 
-
 if __name__ == "__main__":
+
+    retry_count = 0
     io_reg_write(NVRAM_RES, 0x49, COLD_RESET)
-    if not os.path.isdir("/sys/class/gpio/gpio10"):
-        gpio_export(10)
-    gpio_direction("10", "out")
-    # Toggle GPIO10 pin (to reset MUX)
-    gpio_set("10", 1)
-    gpio_set("10", 0)
-    power_reset(1)
+
+    while retry_count < 3:
+        if not os.path.isdir("/sys/class/gpio/gpio10"):
+            gpio_export(10)
+        gpio_direction("10", "out")
+        # Toggle GPIO10 pin (to reset MUX)
+        gpio_set("10", 1)
+        gpio_set("10", 0)
+        power_reset(1)
+        retry_count += 1
+    io_reg_write(PORT_RES, RESET_REG, COLD_RESET)