## ## This file is part of the libsigrokdecode project. ## ## Copyright (C) 2012 Uwe Hermann ## ## 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)