[sonic-platform-modules-dell] Graceful platform reboot (#2912)

The following commit addresses the graceful unmounting of file
system and graceful shutdown of dockers before calling a
cold reboot which will cause a power cycle of SSD. This ensures
orderly shutdown and no corruption of files systems because
of the power cycle to SSD.
This commit will use the existing systemd-reboot service scripts
and override the configuration to do cold reboot for S6100 and
Z9100.
Unit tested the fix and graceful shutdown of file system and
dockers are done with cold reboot.

Signed-off-by: Harish Venkatraman <harish_venkatraman@dell.com>

platform/broadcom/sonic-platform-modules-dell/debian/platform-modules-s6100.install

@@ -2,8 +2,9 @@ s6100/scripts/iom_power_*.sh usr/local/bin
 s6100/scripts/s6100_platform.sh usr/local/bin
 common/dell_i2c_utils.sh usr/local/bin
 common/io_rd_wr.py usr/local/bin
+s6100/scripts/platform_reboot_override usr/share/sonic/device/x86_64-dell_s6100_c2538-r0
+s6100/scripts/override.conf /etc/systemd/system/systemd-reboot.service.d
 common/dell_lpc_mon.sh usr/local/bin
-common/platform_reboot usr/share/sonic/device/x86_64-dell_s6100_c2538-r0
 s6100/scripts/platform_sensors.py usr/local/bin
 s6100/modules/sonic_platform-1.0-py2-none-any.whl usr/share/sonic/device/x86_64-dell_s6100_c2538-r0
 s6100/scripts/platform_watchdog_enable.sh usr/local/bin

platform/broadcom/sonic-platform-modules-dell/debian/platform-modules-z9100.install

@@ -3,7 +3,8 @@ z9100/scripts/z9100_platform.sh usr/local/bin
 common/dell_i2c_utils.sh usr/local/bin
 common/dell_lpc_mon.sh usr/local/bin
 common/io_rd_wr.py usr/local/bin
-common/platform_reboot usr/share/sonic/device/x86_64-dell_z9100_c2538-r0
+z9100/scripts/platform_reboot_override usr/share/sonic/device/x86_64-dell_z9100_c2538-r0
+z9100/scripts/override.conf /etc/systemd/system/systemd-reboot.service.d
 z9100/scripts/platform_sensors.py usr/local/bin
 z9100/scripts/sensors usr/bin
 z9100/modules/sonic_platform-1.0-py2-none-any.whl usr/share/sonic/device/x86_64-dell_z9100_c2538-r0

platform/broadcom/sonic-platform-modules-dell/s6100/scripts/override.conf

@@ -0,0 +1,3 @@
+[Service]
+ExecStart=
+ExecStart=/usr/share/sonic/device/x86_64-dell_s6100_c2538-r0/platform_reboot_override

platform/broadcom/sonic-platform-modules-dell/s6100/scripts/platform_reboot_override

@@ -0,0 +1,25 @@
+#!/usr/bin/python
+import sys
+import os
+import struct
+
+PORT_RES = '/dev/port'
+
+
+def portio_reg_write(resource, offset, val):
+    fd = os.open(resource, os.O_RDWR)
+    if(fd < 0):
+        print 'file open failed %s" % resource'
+        return
+    if(os.lseek(fd, offset, os.SEEK_SET) != offset):
+        print 'lseek failed on %s' % resource
+        return
+    ret = os.write(fd, struct.pack('B', val))
+    if(ret != 1):
+        print 'write failed %d' % ret
+        return
+    os.close(fd)
+
+if __name__ == "__main__":
+    portio_reg_write(PORT_RES, 0xcf9, 0xe)
+

platform/broadcom/sonic-platform-modules-dell/z9100/scripts/override.conf

@@ -0,0 +1,3 @@
+[Service]
+ExecStart=
+ExecStart=/usr/share/sonic/device/x86_64-dell_z9100_c2538-r0/platform_reboot_override

platform/broadcom/sonic-platform-modules-dell/z9100/scripts/platform_reboot_override

@@ -0,0 +1,25 @@
+#!/usr/bin/python
+import sys
+import os
+import struct
+
+PORT_RES = '/dev/port'
+
+
+def portio_reg_write(resource, offset, val):
+    fd = os.open(resource, os.O_RDWR)
+    if(fd < 0):
+        print 'file open failed %s" % resource'
+        return
+    if(os.lseek(fd, offset, os.SEEK_SET) != offset):
+        print 'lseek failed on %s' % resource
+        return
+    ret = os.write(fd, struct.pack('B', val))
+    if(ret != 1):
+        print 'write failed %d' % ret
+        return
+    os.close(fd)
+
+if __name__ == "__main__":
+    portio_reg_write(PORT_RES, 0xcf9, 0xe)
+