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simple spi (#2461)

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(cherry picked from commit 835e4c31d9514f9d06c341479237c35349e75136)
This commit is contained in:
Adeeb Shihadeh
2026-10-14 07:58:12 -07:00
committed by firestar5683
parent a0c5371835
commit 0ddd3f254f
10 changed files with 391 additions and 502 deletions
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panda/python/__init__.py
+3 -8
View File
@@ -251,10 +251,10 @@ class Panda:
return isinstance(self._handle, PandaSpiHandle)
@classmethod
def spi_connect(cls, serial, ignore_version=False):
def spi_connect(cls, serial):
try:
handle = PandaSpiHandle()
dat = handle.get_protocol_version()
dat = handle.get_info()
except PandaSpiException:
return None, None, None, False
@@ -263,16 +263,11 @@ class Panda:
if pid not in (0xcc, 0xee):
raise PandaProtocolMismatch(f"invalid bootstub status ({pid=}). reflash panda")
bootstub = pid == 0xee
spi_version = dat[14]
# did we get the right panda?
if serial is not None and spi_serial != serial:
return None, None, None, False
# ensure our protocol version matches the panda
if (not ignore_version) and spi_version != handle.PROTOCOL_VERSION:
raise PandaProtocolMismatch(f"panda protocol mismatch: expected {handle.PROTOCOL_VERSION}, got {spi_version}. reflash panda")
# got a device and all good
return None, handle, spi_serial, bootstub
@@ -350,7 +345,7 @@ class Panda:
@classmethod
def spi_list(cls):
_, _, serial, _ = cls.spi_connect(None, ignore_version=True)
_, _, serial, _ = cls.spi_connect(None)
if serial is not None:
return [serial, ]
return []
panda/python/jungle.py
+1 -1
View File
@@ -33,7 +33,7 @@ class PandaJungle(Panda):
HARNESS_ORIENTATION_2 = 2
@classmethod
def spi_connect(cls, serial, ignore_version=False):
def spi_connect(cls, serial):
return None, None, None, None
def flash(self, fn=None, code=None, reconnect=True):
panda/python/spi.py
+97 -156
View File
@@ -9,39 +9,32 @@ from contextlib import contextmanager
from functools import reduce
from .base import BaseHandle, BaseSTBootloaderHandle, TIMEOUT
from .constants import McuType, MCU_TYPE_BY_IDCODE, USBPACKET_MAX_SIZE
from .constants import McuType, MCU_TYPE_BY_IDCODE
from .utils import logger
# Constants
SYNC = 0x5A
HACK = 0x79
DACK = 0x85
NACK = 0x1F
CHECKSUM_START = 0xAB
# Protocol, see board/drivers/spi.h
SLAVE_READY = 0x3C
ACK = 0xC3
NACK = 0x5A
INFO_ENDPOINT = 0xF0
MIN_ACK_TIMEOUT_MS = 100
MAX_XFER_RETRY_COUNT = 5
REQ_HEADER = struct.Struct("<BIHH") # endpoint, id, tx_len, rx_len
RESP_HEADER = struct.Struct("<BIH") # status, id, len
CRC = struct.Struct("<I")
RESP_OVERHEAD = RESP_HEADER.size + CRC.size
POLL = 0xFF # filler while reading the response, never a valid request
SPI_BUF_SIZE = 4096 # from panda/board/drivers/spi.h
MIN_TIMEOUT_MS = 100
SILENT_TIMEOUT = 1.0 # seconds, longer than the slowest request takes on the panda
MAX_XFER_RETRY_COUNT = 5 # ST bootloader
SPI_BUF_SIZE = 4096 # from panda/board/drivers/drivers.h
XFER_SIZE = SPI_BUF_SIZE - 0x40 # give some room for SPI protocol overhead
FIRST_READ_SIZE = 1024 - RESP_OVERHEAD # reads are usually small, start small
DEV_PATH = "/dev/spidev0.0"
def crc8(data):
crc = 0xFF # standard init value
poly = 0xD5 # standard crc8: x8+x7+x6+x4+x2+1
size = len(data)
for i in range(size - 1, -1, -1):
crc ^= data[i]
for _ in range(8):
if ((crc & 0x80) != 0):
crc = ((crc << 1) ^ poly) & 0xFF
else:
crc <<= 1
return crc
class PandaSpiException(Exception):
pass
@@ -57,12 +50,6 @@ class PandaSpiNackResponse(PandaSpiException):
class PandaSpiMissingAck(PandaSpiException):
pass
class PandaSpiBadChecksum(PandaSpiException):
pass
class PandaSpiTransferFailed(PandaSpiException):
pass
SPI_LOCK = threading.Lock()
SPI_DEVICES = {}
@@ -166,140 +153,93 @@ class PandaSpiHandle(BaseHandle):
A class that mimics a libusb1 handle for panda SPI communications.
"""
PROTOCOL_VERSION = 2
HEADER = struct.Struct("<BBHH")
def __init__(self) -> None:
self.dev = SpiDevice()
self.no_retry = "NO_RETRY" in os.environ
# helpers
def _calc_checksum(self, data: bytes) -> int:
cksum = CHECKSUM_START
for b in data:
cksum ^= b
return cksum
def _transfer_spidev(self, spi, endpoint: int, req_id: int, data, deadline: float, max_rx_len: int, expect_disconnect: bool) -> bytes | None:
"""One request and its response. Retries until the panda got the request and we got its response, or the deadline.
Returns None if the panda went quiet, so the caller can let go of the bus for a bit."""
# the response is always read in one transfer of rx_len
rx_len = max_rx_len + RESP_OVERHEAD
packet = REQ_HEADER.pack(endpoint, req_id, len(data), rx_len) + bytes(data)
packet += CRC.pack(binascii.crc32(packet))
poll = bytes([POLL, ]) * rx_len
def _wait_for_ack(self, spi, ack_val: int, timeout: int, tx: int, length: int = 1) -> bytes:
timeout_s = max(MIN_ACK_TIMEOUT_MS, timeout) * 1e-3
# when the panda last showed it's there
alive = time.monotonic()
while True:
# send the request, until the panda was ready for it
if spi.xfer2(packet)[0] == SLAVE_READY:
alive = time.monotonic()
if expect_disconnect:
return b""
start = time.monotonic()
while (timeout == 0) or ((time.monotonic() - start) < timeout_s):
dat = spi.xfer2([tx, ] * length)
if dat[0] == ack_val:
return bytes(dat)
elif dat[0] == NACK:
raise PandaSpiNackResponse
raise PandaSpiMissingAck
def _transfer_spidev(self, spi, endpoint: int, data, timeout: int, max_rx_len: int = 1000, expect_disconnect: bool = False) -> bytes:
max_rx_len = max(USBPACKET_MAX_SIZE, max_rx_len)
logger.debug("- send header")
packet = self.HEADER.pack(SYNC, endpoint, len(data), max_rx_len)
packet += bytes([self._calc_checksum(packet), ])
spi.xfer2(packet)
logger.debug("- waiting for header ACK")
self._wait_for_ack(spi, HACK, MIN_ACK_TIMEOUT_MS, 0x11)
logger.debug("- sending data")
packet = bytes([*data, self._calc_checksum(data)])
spi.xfer2(packet)
if expect_disconnect:
logger.debug("- expecting disconnect, returning")
return b""
else:
logger.debug("- waiting for data ACK")
preread_len = USBPACKET_MAX_SIZE + 1 # read enough for a controlRead
dat = self._wait_for_ack(spi, DACK, timeout, 0x13, length=3 + preread_len)
# get response length, then response
response_len = struct.unpack("<H", dat[1:3])[0]
if response_len > max_rx_len:
raise PandaSpiException(f"response length greater than max ({max_rx_len} {response_len})")
# read rest
remaining = (response_len + 1) - preread_len
if remaining > 0:
dat += bytes(spi.readbytes(remaining))
dat = dat[:3 + response_len + 1]
if self._calc_checksum(dat) != 0:
raise PandaSpiBadChecksum
return dat[3:-1]
def _transfer(self, endpoint: int, data, timeout: int, max_rx_len: int = 1000, expect_disconnect: bool = False) -> bytes:
logger.debug("starting transfer: endpoint=%d, max_rx_len=%d", endpoint, max_rx_len)
logger.debug("==============================================")
n = 0
start_time = time.monotonic()
exc = PandaSpiException()
while (timeout == 0) or (time.monotonic() - start_time) < timeout*1e-3:
n += 1
logger.debug("\ntry #%d", n)
with self.dev.acquire() as spi:
try:
return self._transfer_spidev(spi, endpoint, data, timeout, max_rx_len, expect_disconnect)
except PandaSpiException as e:
exc = e
logger.debug("SPI transfer failed, retrying", exc_info=True)
if self.no_retry:
# read until the response. if the panda is ready again, it never got the request
while True:
dat = spi.xfer(poll)
if dat[0] == SLAVE_READY:
alive = time.monotonic()
break
# ensure slave is in a consistent state and ready for the next transfer
# (e.g. slave TX buffer isn't stuck full)
nack_cnt = 0
attempts = 5
while (nack_cnt <= 3) and (attempts > 0):
attempts -= 1
try:
self._wait_for_ack(spi, NACK, MIN_ACK_TIMEOUT_MS, 0x11, length=XFER_SIZE//2)
nack_cnt += 1
except PandaSpiException:
nack_cnt = 0
# a response that got cut off or corrupted isn't one, keep reading
status, resp_id, response_len = RESP_HEADER.unpack_from(dat)
end = RESP_HEADER.size + response_len
if status in (ACK, NACK) and response_len <= max_rx_len and CRC.unpack_from(dat, end)[0] == binascii.crc32(dat[:end]):
# otherwise it's the response to an old request, and we send ours again
if resp_id == req_id:
if status == NACK:
raise PandaSpiNackResponse
return dat[RESP_HEADER.size:end]
alive = time.monotonic()
break
raise exc
if time.monotonic() > min(deadline, alive + SILENT_TIMEOUT):
break
def get_protocol_version(self) -> bytes:
vers_str = b"VERSION"
def _get_version(spi) -> bytes:
spi.writebytes(vers_str)
if time.monotonic() > deadline:
raise PandaSpiMissingAck
if time.monotonic() > alive + SILENT_TIMEOUT:
return None
logger.debug("- waiting for echo")
start = time.monotonic()
while True:
version_bytes = spi.readbytes(len(vers_str) + 2)
if bytes(version_bytes).startswith(vers_str):
break
if (time.monotonic() - start) > 0.001:
raise PandaSpiMissingAck
def _transfer(self, endpoint: int, data, timeout: int, max_rx_len: int = 0, expect_disconnect: bool = False) -> bytes:
logger.debug("transfer: endpoint=%d, max_rx_len=%d", endpoint, max_rx_len)
rlen = struct.unpack("<H", bytes(version_bytes[-2:]))[0]
if rlen > 1000:
raise PandaSpiException("response length greater than max")
# timeout of 0 means forever
deadline = time.monotonic() + (max(MIN_TIMEOUT_MS, timeout) * 1e-3 if timeout != 0 else math.inf)
nack = None
nack_count = 0
# random, so it's never the same as another request the panda just handled, even from another client.
# it stays the same when we send the request again, so the panda never runs it twice
req_id = int.from_bytes(os.urandom(4), "little")
while True:
try:
with self.dev.acquire() as spi:
dat = self._transfer_spidev(spi, endpoint, req_id, data, deadline, max_rx_len, expect_disconnect)
if dat is not None:
return dat
# the panda went quiet. let go of the bus for a bit, someone else might need it
logger.warning("SPI: panda isn't responding")
time.sleep(0.01)
except PandaSpiNackResponse as e:
# the panda NACKs while its CAN TX buffers are full, don't busy wait on it
if time.monotonic() > deadline:
raise
# a new id, since the panda would answer the same id with the same NACK
req_id = int.from_bytes(os.urandom(4), "little")
nack = e
nack_count += 1
if nack_count > 3:
time.sleep(min(max(nack_count * 10, 200), 2000) * 1e-6)
except PandaSpiMissingAck:
# only raised once the deadline passed. if the panda was refusing, that's why
if nack is not None:
raise nack from None
raise
# get response
dat = spi.readbytes(rlen + 1)
resp = dat[:-1]
calculated_crc = crc8(bytes(version_bytes + resp))
if calculated_crc != dat[-1]:
raise PandaSpiBadChecksum
return bytes(resp)
exc = PandaSpiException()
with self.dev.acquire() as spi:
for _ in range(10):
try:
return _get_version(spi)
except PandaSpiException as e:
exc = e
logger.debug("SPI get protocol version failed, retrying", exc_info=True)
raise exc
def get_info(self) -> bytes:
# serial, HW type, bootstub
return self._transfer(INFO_ENDPOINT, b"", MIN_TIMEOUT_MS, max_rx_len=14)
# libusb1 functions
def close(self):
@@ -313,16 +253,17 @@ class PandaSpiHandle(BaseHandle):
def bulkWrite(self, endpoint: int, data: bytes, timeout: int = TIMEOUT) -> int:
mv = memoryview(data)
for x in range(math.ceil(len(data) / XFER_SIZE)):
self._transfer(endpoint, mv[XFER_SIZE*x:XFER_SIZE*(x+1)], timeout)
for x in range(0, len(data), XFER_SIZE):
self._transfer(endpoint, mv[x:x+XFER_SIZE], timeout)
return len(data)
def bulkRead(self, endpoint: int, length: int, timeout: int = TIMEOUT) -> bytes:
ret = b""
for _ in range(math.ceil(length / XFER_SIZE)):
d = self._transfer(endpoint, [], timeout, max_rx_len=XFER_SIZE)
while len(ret) < length:
to_read = min(XFER_SIZE if len(ret) else FIRST_READ_SIZE, length - len(ret))
d = self._transfer(endpoint, b"", timeout, max_rx_len=to_read)
ret += d
if len(d) < XFER_SIZE:
if len(d) < to_read:
break
return ret