#!/bin/bash

# PFR Boot Time Detection
#
# The Platform Firmware Recovery system is designed to confirm the server is
# running valid images. The server boot process is controlled with a
# programmable device. The programmable device prevents the system, and the
# BMC from booting until after it has confirmed the firmware images match a
# known checksum. Two reset controls are asserted while the checksum
# calculation is being performed. One prevents the BMC from booting, the other
# (RSMRST_N) prevents the main processors from leaving reset.
#
# If the BMC FW checksum is correct the BMC is allowed to boot.
# If the BIOS checksum fails the BIOS is not allowed to boot.
# In this condition the BMC will boot believing the NCSI NIC is functional.
# This will not be the case when RMSRST_N is asserted. The BIOS will not
# configure the shared NIC. The BMC will not be able to send or receive
# network traffic via the shared NIC. This becomes a problem depending on how
# the NCSI channel is configured.
#
# When the NCSI channel is configured using DHCP the BMC is unable to
# communicate to a DHCP server. Unable to acquire a valid IP state, the NCSI
# NIC is left DOWN.
# The problem that occurs is when the NIC is configured with a static
# address. The BMC is unable to determine the configuration state of the NCSI
# NIC, and behaves as if everything is working. The problem is the network
# routing table will, in most cases, be left in a state that prevents traffic
# from being sent/received from the dedicated NIC. This prevents network
# access to the BMC, which in turn leaves the system unrecoverable.
#
# The purpose of this script is to check for the assertion of the RSMRST_N
# control at BMC boot time. It will perform this test once. In the event the
# RSMRST_N is found to be asserted, the BMC will take the NCSI NIC down. No
# logic for detecting the deassertion will be performed. Once the new image
# for the BIOS has been transferred, and the checksum confirmed, the BMC will
# be reset by the programmable device. The programmable device will confirm
# the checksums, and release both the BMC and the BIOS to boot normally.
#
# Flow:
# The service will be a one-shot that waits for the network.target, as is done
# by BMCWeb.
# During a normal boot the RSMRST_N will not be asserted, and this script will
# not perform an action.
# When RSMRST_N is asserted the NCSI channel will be given a link down
# command. This regardless of static or DHCP configuration mode.

GPIOFIND=/usr/bin/gpiofind
GPIOGET=/usr/bin/gpioget
RSMRST="RSMRST_N"

# Read the assertion state from the RSMRST_N input
function get_rsmrst_state {
    local __resultVal=$1
    local gpioFound=$($GPIOFIND $RSMRST)
    # Test to see if the RSMRST_N input exists. This test does not cover the
    # case where an input is already owned by another service/process.
    if [ -z "$gpioFound" ]
    then
        return 1
    fi
    local gpio_state=$($GPIOGET $gpioFound)
    eval $__resultVal="'$gpio_state'"
    return 0
}

get_rsmrst_state rsmrst_val
if [[ $? == 0 && $rsmrst_val -eq 0 ]]
then
    echo "RSMRST_N is asserted, take eth1 down"
    ip link set down dev eth1
fi