+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Angus Gratton <gus@projectgus.com>
+##
+## 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
+##
+
+import sigrokdecode as srd
+import re, traceback
+
+'''
+OUTPUT_PYTHON format:
+
+Packet:
+[<ptype>, <pdata>]
+
+<ptype>:
+ - 'AP_READ' (AP read)
+ - 'DP_READ' (DP read)
+ - 'AP_WRITE' (AP write)
+ - 'DP_WRITE' (DP write)
+ - 'LINE_RESET' (line reset sequence)
+
+<pdata>:
+ - tuple of address, ack state, data for the given sequence
+'''
+
+swd_states = [
+ 'IDLE', # Idle/unknown
+ 'REQUEST', # Request phase (first 8 bits)
+ 'ACK', # Ack phase (next 3 bits)
+ 'READ', # Reading phase (next 32 bits for reads)
+ 'WRITE', # Writing phase (next 32 bits for write)
+ 'DPARITY', # Data parity phase
+]
+
+# Regexes for matching SWD data out of bitstring ('1' / '0' characters) format
+RE_SWDSWITCH = re.compile(bin(0xE79E)[:1:-1] + '$')
+RE_SWDREQ = re.compile(r'1(?P<apdp>.)(?P<rw>.)(?P<addr>..)(?P<parity>.)01$')
+RE_IDLE = re.compile('0' * 50 + '$')
+
+# Sample edges
+RISING = 1
+FALLING = 0
+
+ADDR_DP_SELECT = 0x8
+ADDR_DP_CTRLSTAT = 0x4
+
+BIT_SELECT_CTRLSEL = 1
+BIT_CTRLSTAT_ORUNDETECT = 1
+
+ANNOTATIONS = ['reset', 'enable', 'read', 'write', 'ack', 'data', 'parity']
+
+class Decoder(srd.Decoder):
+ api_version = 2
+ id = 'swd'
+ name = 'SWD'
+ longname = 'Serial Wire Debug'
+ desc = 'Two-wire protocol for debug access to ARM CPUs.'
+ license = 'gplv2+'
+ inputs = ['logic']
+ outputs = ['swd']
+ channels = (
+ {'id': 'swclk', 'name': 'SWCLK', 'desc': 'Master clock'},
+ {'id': 'swdio', 'name': 'SWDIO', 'desc': 'Data input/output'},
+ )
+ options = (
+ {'id': 'strict_start',
+ 'desc': 'Wait for a line reset before starting to decode',
+ 'default': 'no', 'values': ('yes', 'no')},
+ )
+ annotations = (
+ ('reset', 'RESET'),
+ ('enable', 'ENABLE'),
+ ('read', 'READ'),
+ ('write', 'WRITE'),
+ ('ack', 'ACK'),
+ ('data', 'DATA'),
+ ('parity', 'PARITY'),
+ )
+
+ def __init__(self, **kwargs):
+ # SWD data/clock state
+ self.state = 'UNKNOWN'
+ self.oldclk = -1
+ self.sample_edge = RISING
+ self.ack = None # Ack state of the current phase
+ self.ss_req = 0 # Start sample of current req
+ self.turnaround = 0 # Number of turnaround edges to ignore before continuing
+ self.bits = '' # Bits from SWDIO are accumulated here, matched against expected sequences
+ self.samplenums = [] # Sample numbers that correspond to the samples in self.bits
+ self.linereset_count = 0
+
+ # SWD debug port state
+ self.data = None
+ self.addr = None
+ self.rw = None # Are we inside an SWD read or a write?
+ self.ctrlsel = 0 # 'ctrlsel' is bit 0 in the SELECT register.
+ self.orundetect = 0 # 'orundetect' is bit 0 in the CTRLSTAT register.
+
+ def start(self):
+ self.out_ann = self.register(srd.OUTPUT_ANN)
+ self.out_python = self.register(srd.OUTPUT_PYTHON)
+ if self.options['strict_start'] == 'no':
+ self.state = 'REQ' # No need to wait for a LINE RESET.
+
+ def putx(self, ann, length, data):
+ '''Output annotated data.'''
+ ann = ANNOTATIONS.index(ann)
+ try:
+ ss = self.samplenums[-length]
+ except IndexError:
+ ss = self.samplenums[0]
+ if self.state == 'REQ':
+ self.ss_req = ss
+ es = self.samplenum
+ self.put(ss, es, self.out_ann, [ann, [data]])
+
+ def putp(self, ptype, pdata):
+ self.put(self.ss_req, self.samplenum, self.out_python, [ptype, pdata])
+
+ def put_python_data(self):
+ '''Emit Python data item based on current SWD packet contents.'''
+ ptype = {
+ ('AP', 'R'): 'AP_READ',
+ ('AP', 'W'): 'AP_WRITE',
+ ('DP', 'R'): 'DP_READ',
+ ('DP', 'W'): 'DP_WRITE',
+ }[(self.apdp, self.rw)]
+ self.putp(ptype, (self.addr, self.data, self.ack))
+
+ def decode(self, ss, es, data):
+ try:
+ return self._decode(ss, es, data)
+ except:
+ traceback.print_exc()
+ raise
+
+ def _decode(self, ss, es, data):
+ for (self.samplenum, (clk, dio)) in data:
+ if clk == self.oldclk:
+ continue # Not a clock edge.
+ self.oldclk = clk
+
+ # Count rising edges with DIO held high,
+ # as a line reset (50+ high edges) can happen from any state.
+ if clk == RISING:
+ if dio == 1:
+ self.linereset_count += 1
+ else:
+ if self.linereset_count >= 50:
+ self.putx('reset', self.linereset_count, 'LINERESET')
+ self.putp('LINE_RESET', None)
+ self.reset_state()
+ self.linereset_count = 0
+
+ # Otherwise, we only care about either rising or falling edges
+ # (depending on sample_edge, set according to current state).
+ if clk != self.sample_edge:
+ continue
+
+ # Turnaround bits get skipped.
+ if self.turnaround > 0:
+ self.turnaround -= 1
+ continue
+
+ self.bits += str(dio)
+ self.samplenums.append(self.samplenum)
+ {
+ 'UNKNOWN': self.handle_unknown_edge,
+ 'REQ': self.handle_req_edge,
+ 'ACK': self.handle_ack_edge,
+ 'DATA': self.handle_data_edge,
+ 'DPARITY': self.handle_dparity_edge,
+ }[self.state]()
+
+ def next_state(self):
+ '''Step to the next SWD state, reset internal counters accordingly.'''
+ self.bits = ''
+ self.samplenums = []
+ self.linereset_count = 0
+ if self.state == 'UNKNOWN':
+ self.state = 'REQ'
+ self.sample_edge = RISING
+ self.turnaround = 0
+ elif self.state == 'REQ':
+ self.state = 'ACK'
+ self.sample_edge = FALLING
+ self.turnaround = 1
+ elif self.state == 'ACK':
+ self.state = 'DATA'
+ self.sample_edge = RISING if self.rw == 'W' else FALLING
+ self.turnaround = 0 if self.rw == 'R' else 2
+ elif self.state == 'DATA':
+ self.state = 'DPARITY'
+ elif self.state == 'DPARITY':
+ self.put_python_data()
+ self.state = 'REQ'
+ self.sample_edge = RISING
+ self.turnaround = 1 if self.rw == 'R' else 0
+
+ def reset_state(self):
+ '''Line reset (or equivalent), wait for a new pending SWD request.'''
+ if self.state != 'REQ': # Emit a Python data item.
+ self.put_python_data()
+ # Clear state.
+ self.bits = ''
+ self.samplenums = []
+ self.linereset_count = 0
+ self.turnaround = 0
+ self.sample_edge = RISING
+ self.data = ''
+ self.ack = None
+ self.state = 'REQ'
+
+ def handle_unknown_edge(self):
+ '''
+ Clock edge in the UNKNOWN state.
+ In the unknown state, clock edges get ignored until we see a line
+ reset (which is detected in the decode method, not here.)
+ '''
+ pass
+
+ def handle_req_edge(self):
+ '''Clock edge in the REQ state (waiting for SWD r/w request).'''
+ # Check for a JTAG->SWD enable sequence.
+ m = re.search(RE_SWDSWITCH, self.bits)
+ if m is not None:
+ self.putx('enable', 16, 'JTAG->SWD')
+ self.reset_state()
+ return
+
+ # Or a valid SWD Request packet.
+ m = re.search(RE_SWDREQ, self.bits)
+ if m is not None:
+ calc_parity = sum([int(x) for x in m.group('rw') + m.group('apdp') + m.group('addr')]) % 2
+ parity = '' if str(calc_parity) == m.group('parity') else 'E'
+ self.rw = 'R' if m.group('rw') == '1' else 'W'
+ self.apdp = 'AP' if m.group('apdp') == '1' else 'DP'
+ self.addr = int(m.group('addr')[::-1], 2) << 2
+ self.putx('read' if self.rw == 'R' else 'write', 8, self.get_address_description())
+ self.next_state()
+ return
+
+ def handle_ack_edge(self):
+ '''Clock edge in the ACK state (waiting for complete ACK sequence).'''
+ if len(self.bits) < 3:
+ return
+ if self.bits == '100':
+ self.putx('ack', 3, 'OK')
+ self.ack = 'OK'
+ self.next_state()
+ elif self.bits == '001':
+ self.putx('ack', 3, 'FAULT')
+ self.ack = 'FAULT'
+ if self.orundetect == 1:
+ self.next_state()
+ else:
+ self.reset_state()
+ self.turnaround = 1
+ elif self.bits == '010':
+ self.putx('ack', 3, 'WAIT')
+ self.ack = 'WAIT'
+ if self.orundetect == 1:
+ self.next_state()
+ else:
+ self.reset_state()
+ self.turnaround = 1
+ elif self.bits == '111':
+ self.putx('ack', 3, 'NOREPLY')
+ self.ack = 'NOREPLY'
+ self.reset_state()
+ else:
+ self.putx('ack', 3, 'ERROR')
+ self.ack = 'ERROR'
+ self.reset_state()
+
+ def handle_data_edge(self):
+ '''Clock edge in the DATA state (waiting for 32 bits to clock past).'''
+ if len(self.bits) < 32:
+ return
+ self.data = 0
+ self.dparity = 0
+ for x in range(32):
+ if self.bits[x] == '1':
+ self.data += (1 << x)
+ self.dparity += 1
+ self.dparity = self.dparity % 2
+
+ self.putx('data', 32, '0x%08x' % self.data)
+ self.next_state()
+
+ def handle_dparity_edge(self):
+ '''Clock edge in the DPARITY state (clocking in parity bit).'''
+ if str(self.dparity) != self.bits:
+ self.putx('parity', 1, str(self.dparity) + self.bits) # PARITY ERROR
+ elif self.rw == 'W':
+ self.handle_completed_write()
+ self.next_state()
+
+ def handle_completed_write(self):
+ '''
+ Update internal state of the debug port based on a completed
+ write operation.
+ '''
+ if self.apdp != 'DP':
+ return
+ elif self.addr == ADDR_DP_SELECT:
+ self.ctrlsel = self.data & BIT_SELECT_CTRLSEL
+ elif self.addr == ADDR_DP_CTRLSTAT and self.ctrlsel == 0:
+ self.orundetect = self.data & BIT_CTRLSTAT_ORUNDETECT
+
+ def get_address_description(self):
+ '''
+ Return a human-readable description of the currently selected address,
+ for annotated results.
+ '''
+ if self.apdp == 'DP':
+ if self.rw == 'R':
+ # Tables 2-4 & 2-5 in ADIv5.2 spec ARM document IHI 0031C
+ return {
+ 0: 'IDCODE',
+ 0x4: 'R CTRL/STAT' if self.ctrlsel == 0 else 'R DLCR',
+ 0x8: 'RESEND',
+ 0xC: 'RDBUFF'
+ }[self.addr]
+ elif self.rw == 'W':
+ # Tables 2-4 & 2-5 in ADIv5.2 spec ARM document IHI 0031C
+ return {
+ 0: 'W ABORT',
+ 0x4: 'W CTRL/STAT' if self.ctrlsel == 0 else 'W DLCR',
+ 0x8: 'W SELECT',
+ 0xC: 'W RESERVED'
+ }[self.addr]
+ elif self.apdp == 'AP':
+ if self.rw == 'R':
+ return 'W AP%x' % self.addr
+ elif self.rw == 'W':
+ return 'W AP%x' % self.addr
+
+ # Any legitimate operations shouldn't fall through to here, probably
+ # a decoder bug.
+ return '? %s%s%x' % (self.rw, self.apdp, self.addr)
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