#!/bin/bash
###############################################################################
#                                                                             #
# IPFire.org - A linux based firewall                                         #
# Copyright (C) 2016  IPFire Network Development Team                         #
#                                                                             #
# This program is free software: you can redistribute it and/or modify        #
# it under the terms of the GNU General Public License as published by        #
# the Free Software Foundation, either version 3 of the License, or           #
# (at your option) any later version.                                         #
#                                                                             #
# This program is distributed in the hope that it will be useful,             #
# but WITHOUT ANY WARRANTY; without even the implied warranty of              #
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
# GNU General Public License for more details.                                #
#                                                                             #
# You should have received a copy of the GNU General Public License           #
# along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
#                                                                             #
###############################################################################

interrupts_list() {
	local interrupt
	for interrupt in list_directory "/proc/irq"; do
		if interrupt_exists "${interrupt}"; then
			print "${interrupt}"
		fi
	done
}

interrupt_exists() {
	local interrupt="${1}"

	[ -d "/proc/irq/${interrupt}" ]
}

interrupt_use_smp_affinity() {
	local processors=$(system_get_processors)

	# There is no point in this feature when there is only one processor
	[ ${processors} -eq 1 ] && return ${EXIT_FALSE}

	return ${EXIT_TRUE}
}

__interrupts_for() {
	local path=${1}

	local f
	for f in ${path}; do
		[ -d "${f}" ] || continue

		local interrupt=$(dirname ${f})
		basename ${interrupt}
	done
}

interrupts_for_device() {
	assert [ $# -eq 1 ]

	local device=${1}

	__interrupts_for "/proc/irq/*/${device}"
}

interrupts_for_device_queue() {
	assert [ $# -eq 2 ]

	local device="${1}"
	local queue="${2}"

	__interrupts_for "/proc/irq/*/${device}-[rt]x${queue}"
}

interrupt_get_smp_affinity() {
	assert [ $# -eq 1 ]

	local interrupt=${1}

	local path="/proc/irq/${interrupt}/smp_affinity"
	assert [ -r "${path}" ]

	# Convert bitmap to list of processors
	__bitmap_to_processor_ids $(<${path})
}

__bitmap_to_processor_ids() {
	local bitmap=${1}

	# This function shifts the bit map to the right
	# and if the least significant bit equals one
	# the index of that bit is returned.

	local id=0
	while [ $(( 0x${bitmap} )) -gt 0 ]; do
		if [ $(( 0x${bitmap} & 0x1 )) -eq 1 ]; then
			print "${id}"
		fi

		bitmap=$(( 0x${bitmap} >> 1 ))
		((id++))
	done
}

__processor_id_to_bitmap() {
	hex $(( 1 << $@ ))
}

interrupt_set_smp_affinity() {
	assert [ $# -eq 2 ]

	local interrupt=${1}
	local processor=${2}

	# Processor ID must be greater or equal than zero
	# and not larger than the highest processor index
	local num_processors=$(system_get_processors)
	if [ ${processor} -ge ${num_processors} ]; then
		error "Invalid processor ID ${processor}"
		return ${EXIT_ERROR}
	fi

	local path="/proc/irq/${interrupt}/smp_affinity"
	assert [ -w "${path}" ]

	log DEBUG "Setting SMP affinity for interrupt ${interrupt} to processor ${processor}"

	# Write processor ID as hex value
	__processor_id_to_bitmap ${processor} > ${path}
}

interrupt_choose_least_busy_processor() {
	local processors=$(system_get_processors)
	local -a interrupts

	# Create an array with the number of interrupts
	# already handled by each processor

	local i
	for i in $(range ${processors}); do
		interrupts[${i}]=0
	done

	local processor interrupt
	for interrupt in $(interrupts_list); do
		for processor in $(interrupt_get_smp_affinity ${interrupt}); do
			interrupts[${processor}]=$(( ${interrupts[${processor}]} + 1 ))
		done
	done

	# Walk through that map and find the first processor with the
	# smallest number of interrupts handled so far

	local least_busy_index=0
	for i in $(range ${processors}); do
		if [ ${interrupts[${least_busy_index}]} -gt ${interrupts[${i}]} ]; then
			least_busy_index=${i}
		fi
	done

	print "${least_busy_index}"
}