##
## This file is part of the sigrok project.
##
## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
##
## 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 2 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, write to the Free Software
## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
##
# LPC protocol decoder
import sigrokdecode as srd
# ...
fields = {
# START field (indicates start or stop of a transaction)
'START': {
0b0000: 'Start of cycle for a target',
0b0001: 'Reserved',
0b0010: 'Grant for bus master 0',
0b0011: 'Grant for bus master 1',
0b0100: 'Reserved',
0b0101: 'Reserved',
0b0110: 'Reserved',
0b0111: 'Reserved',
0b1000: 'Reserved',
0b1001: 'Reserved',
0b1010: 'Reserved',
0b1011: 'Reserved',
0b1100: 'Reserved',
0b1101: 'Start of cycle for a Firmware Memory Read cycle',
0b1110: 'Start of cycle for a Firmware Memory Write cycle',
0b1111: 'Stop/abort (end of a cycle for a target)',
},
# Cycle type / direction field
# Bit 0 (LAD[0]) is unused, should always be 0.
# Neither host nor peripheral are allowed to drive 0b11x0.
'CT_DR': {
0b0000: 'I/O read',
0b0010: 'I/O write',
0b0100: 'Memory read',
0b0110: 'Memory write',
0b1000: 'DMA read',
0b1010: 'DMA write',
0b1100: 'Reserved / not allowed',
0b1110: 'Reserved / not allowed',
},
# SIZE field (determines how many bytes are to be transferred)
# Bits[3:2] are reserved, must be driven to 0b00.
# Neither host nor peripheral are allowed to drive 0b0010.
'SIZE': {
0b0000: '8 bits (1 byte)',
0b0001: '16 bits (2 bytes)',
0b0010: 'Reserved / not allowed',
0b0011: '32 bits (4 bytes)',
},
# CHANNEL field (bits[2:0] contain the DMA channel number)
'CHANNEL': {
0b0000: '0',
0b0001: '1',
0b0010: '2',
0b0011: '3',
0b0100: '4',
0b0101: '5',
0b0110: '6',
0b0111: '7',
},
# SYNC field (used to add wait states)
'SYNC': {
0b0000: 'Ready',
0b0001: 'Reserved',
0b0010: 'Reserved',
0b0011: 'Reserved',
0b0100: 'Reserved',
0b0101: 'Short wait',
0b0110: 'Long wait',
0b0111: 'Reserved',
0b1000: 'Reserved',
0b1001: 'Ready more (DMA only)',
0b1010: 'Error',
0b1011: 'Reserved',
0b1100: 'Reserved',
0b1101: 'Reserved',
0b1110: 'Reserved',
0b1111: 'Reserved',
},
}
class Decoder(srd.Decoder):
api_version = 1
id = 'lpc'
name = 'LPC'
longname = 'Low-Pin-Count'
desc = 'Protocol for low-bandwidth devices on PC mainboards.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['lpc']
probes = [
{'id': 'lframe', 'name': 'LFRAME#', 'desc': 'TODO'},
{'id': 'lreset', 'name': 'LRESET#', 'desc': 'TODO'},
{'id': 'lclk', 'name': 'LCLK', 'desc': 'TODO'},
{'id': 'lad0', 'name': 'LAD[0]', 'desc': 'TODO'},
{'id': 'lad1', 'name': 'LAD[1]', 'desc': 'TODO'},
{'id': 'lad2', 'name': 'LAD[2]', 'desc': 'TODO'},
{'id': 'lad3', 'name': 'LAD[3]', 'desc': 'TODO'},
]
optional_probes = [
{'id': 'ldrq', 'name': 'LDRQ#', 'desc': 'TODO'},
{'id': 'serirq', 'name': 'SERIRQ', 'desc': 'TODO'},
{'id': 'clkrun', 'name': 'CLKRUN#', 'desc': 'TODO'},
{'id': 'lpme', 'name': 'LPME#', 'desc': 'TODO'},
{'id': 'lpcpd', 'name': 'LPCPD#', 'desc': 'TODO'},
{'id': 'lsmi', 'name': 'LSMI#', 'desc': 'TODO'},
]
options = {}
annotations = [
['Text', 'Human-readable text'],
]
def __init__(self, **kwargs):
self.state = 'IDLE'
self.oldlclk = -1
self.samplenum = 0
self.clocknum = 0
self.lad = -1
self.addr = 0
self.cur_nibble = 0
self.cycle_type = -1
self.oldpins = (-1, -1, -1, -1, -1, -1, -1)
def start(self, metadata):
self.out_proto = self.add(srd.OUTPUT_PROTO, 'lpc')
self.out_ann = self.add(srd.OUTPUT_ANN, 'lpc')
def report(self):
pass
def handle_get_start(self, lad, lframe):
# LAD[3:0]: START field (1 clock cycle).
# The last value of LAD[3:0] before LFRAME# gets de-asserted is what
# the peripherals must use. However, the host can keep LFRAME# asserted
# multiple clocks, and we output all START fields that occur, even
# though the peripherals are supposed to ignore all but the last one.
s = fields['START'][lad]
self.put(0, 0, self.out_ann, [0, [s]])
# Output a warning if LAD[3:0] changes while LFRAME# is low.
# TODO
if (self.lad != -1 and self.lad != lad):
self.put(0, 0, self.out_ann,
[0, ['Warning: LAD[3:0] changed while '
'LFRAME# was asserted']])
# LFRAME# is asserted (low). Wait until it gets de-asserted again
# (the host is allowed to keep it asserted multiple clocks).
if lframe != 1:
return
self.start_field = self.lad
self.state = 'GET CT/DR'
def handle_get_ct_dr(self, lad, lad_bits):
# LAD[3:0]: Cycle type / direction field (1 clock cycle).
self.cycle_type = fields['CT_DR'][lad]
# TODO: Warning/error on invalid cycle types.
if self.cycle_type == 'Reserved':
self.put(0, 0, self.out_ann,
[0, ['Warning: Invalid cycle type (%s)' % lad_bits]])
# ...
self.put(0, 0, self.out_ann, [0, ['Cycle type: %s' % self.cycle_type]])
self.state = 'GET ADDR'
self.addr = 0
self.cur_nibble = 0
def handle_get_addr(self, lad, lad_bits):
# LAD[3:0]: ADDR field (4/8/0 clock cycles).
# I/O cycles: 4 ADDR clocks. Memory cycles: 8 ADDR clocks.
# DMA cycles: no ADDR clocks at all.
if self.cycle_type in ('I/O read', 'I/O write'):
addr_nibbles = 4 # Address is 16bits.
elif self.cycle_type in ('Memory read', 'Memory write'):
addr_nibbles = 8 # Address is 32bits.
else:
addr_nibbles = 0 # TODO: How to handle later on?
# Data is driven MSN-first.
offset = ((addr_nibbles - 1) - self.cur_nibble) * 4
self.addr |= (lad << offset)
# Continue if we haven't seen all ADDR cycles, yet.
# TODO: Off-by-one?
if (self.cur_nibble < addr_nibbles - 1):
self.cur_nibble += 1
return
self.put(0, 0, self.out_ann, [0, ['Address: %s' % hex(self.addr)]])
self.state = 'GET TAR'
self.tar_count = 0
def handle_get_tar(self, lad, lad_bits):
# LAD[3:0]: First TAR (turn-around) field (2 clock cycles).
self.put(0, 0, self.out_ann, [0, ['TAR, cycle %d: %s'
% (self.tarcount, lad_bits)]])
# On the first TAR clock cycle LAD[3:0] is driven to 1111 by
# either the host or peripheral. On the second clock cycle,
# the host or peripheral tri-states LAD[3:0], but its value
# should still be 1111, due to pull-ups on the LAD lines.
if lad_bits != '1111':
self.put(0, 0, self.out_ann,
[0, ['Warning: TAR, cycle %d: %s (expected 1111)'
% (self.tarcount, lad_bits)]])
if (self.tarcount != 2):
self.tarcount += 1
return
self.state = 'GET SYNC'
def handle_get_sync(self, lad, lad_bits):
# LAD[3:0]: SYNC field (1-n clock cycles).
self.sync_val = lad_bits
self.cycle_type = fields['SYNC'][lad]
# TODO: Warnings if reserved value are seen?
if self.cycle_type == 'Reserved':
self.put(0, 0, self.out_ann, [0, ['Warning: SYNC, cycle %d: %s '
'(reserved value)' % (self.synccount, self.sync_val)]])
self.put(0, 0, self.out_ann, [0, ['SYNC, cycle %d: %s'
% (self.synccount, self.sync_val)]])
# TODO
self.state = 'GET DATA'
self.cycle_count = 0
def handle_get_data(self, lad, lad_bits):
# LAD[3:0]: DATA field (2 clock cycles).
if (self.cycle_count == 0):
self.databyte = lad
elif (self.cycle_count == 1):
self.databyte |= (lad << 4)
else:
pass # TODO: Error?
if (self.cycle_count != 2):
self.cycle_count += 1
return
self.put(0, 0, self.out_ann, [0, ['DATA: %s' % hex(self.databyte)]])
self.state = 'GET TAR2'
def handle_get_tar2(self, lad, lad_bits):
# LAD[3:0]: Second TAR field (2 clock cycles).
self.put(0, 0, self.out_ann, [0, ['TAR, cycle %d: %s'
% (self.tarcount, lad_bits)]])
# On the first TAR clock cycle LAD[3:0] is driven to 1111 by
# either the host or peripheral. On the second clock cycle,
# the host or peripheral tri-states LAD[3:0], but its value
# should still be 1111, due to pull-ups on the LAD lines.
if lad_bits != '1111':
self.put(0, 0, self.out_ann,
[0, ['Warning: TAR, cycle %d: %s (expected 1111)'
% (self.tarcount, lad_bits)]])
if (self.tarcount != 2):
self.tarcount += 1
return
self.state = 'GET SYNC'
# TODO: At which edge of the clock is data latched? Falling?
def decode(self, ss, es, data):
for (samplenum, pins) in data:
# If none of the pins changed, there's nothing to do.
if self.oldpins == pins:
continue
# Store current pin values for the next round.
self.oldpins = pins
# Get individual pin values into local variables.
# TODO: Handle optional pins.
(lframe, lreset, lclk, lad0, lad1, lad2, lad3) = pins
# Only look at the signals upon falling LCLK edges.
# TODO: Rising?
## if not (self.oldlclk == 1 and lclk == 0)
## self.oldlclk = lclk
## continue
# Store LAD[3:0] bit values (one nibble) in local variables.
# Most (but not all) states need this.
if self.state != 'IDLE':
lad = (lad3 << 3) | (lad2 << 2) | (lad1 << 1) | lad0
lad_bits = bin(lad)[2:]
# State machine
if self.state == 'IDLE':
# A valid LPC cycle starts with LFRAME# being asserted (low).
# TODO?
if lframe != 0:
continue
self.state = 'GET START'
self.lad = -1
# self.clocknum = 0
elif self.state == 'GET START':
handle_get_start(lad, lad_bits, lframe)
elif self.state == 'GET CT/DR':
handle_get_ct_dr(lad, lad_bits)
elif self.state == 'GET ADDR':
handle_get_addr(lad, lad_bits)
elif self.state == 'GET TAR':
handle_get_tar(lad, lad_bits)
elif self.state == 'GET SYNC':
handle_get_sync(lad, lad_bits)
elif self.state == 'GET DATA':
handle_get_data(lad, lad_bits)
elif self.state == 'GET TAR2':
handle_get_tar2(lad, lad_bits)
else:
raise Exception('Invalid state: %s' % self.state)