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# -*- coding: utf-8 -*-
#
# Driver for FPGA based PROFIBUS PHY.
#
# Copyright (c) 2019 Michael Buesch <m@bues.ch>
#
# Licensed under the terms of the GNU General Public License version 2,
# or (at your option) any later version.
#
from __future__ import division, absolute_import, print_function, unicode_literals
from pyprofibus.compat import *
from pyprofibus.phy_fpga_driver.exceptions import *
__all__ = [
"FpgaPhyMsg",
"FpgaPhyMsgCtrl",
]
class FpgaPhyMsg(object):
SPI_MS_MAGIC = 0xAA
SPI_SM_MAGIC = 0x55
PADDING = 0x00
PADDING_BYTE = bytes([PADDING])
SPI_FLG_START = 0
SPI_FLG_CTRL = 1
SPI_FLG_NEWSTAT = 2
SPI_FLG_RESET = 3
SPI_FLG_UNUSED4 = 4
SPI_FLG_UNUSED5 = 5
SPI_FLG_UNUSED7 = 6
SPI_FLG_PARITY = 7
LEN_UNKNOWN = -1
LEN_NEEDMORE = -2
LEN_ERROR = -3
CRC_POLYNOMIAL = 0x07
SD1 = 0x10
SD2 = 0x68
SD3 = 0xA2
SD4 = 0xDC
SC = 0xE5
@staticmethod
def crc8(dataBytes, crc=0xFF, P=CRC_POLYNOMIAL):
for data in dataBytes:
data ^= crc
for i in range(8):
data = ((data << 1) ^ (P if (data & 0x80) else 0)) & 0xFF
crc = data
return crc
@classmethod
def parity(cls, value):
"""Calculate odd parity on 8 bits.
"""
return ((value & 1) ^
((value >> 1) & 1) ^
((value >> 2) & 1) ^
((value >> 3) & 1) ^
((value >> 4) & 1) ^
((value >> 5) & 1) ^
((value >> 6) & 1) ^
((value >> 7) & 1) ^ 1)
@classmethod
def calcLen(cls, dataBytes):
dataBytesLen = len(dataBytes)
if dataBytesLen > 0:
firstByte = dataBytes[0]
if firstByte == cls.SC:
return 1
elif firstByte == cls.SD1:
return 6
elif firstByte == cls.SD2:
if dataBytesLen >= 4:
lenField = dataBytes[1]
if (lenField == dataBytes[2] and
lenField >= 4 and
lenField <= 249 and
dataBytes[3] == cls.SD2):
return lenField + 6
else:
return cls.LEN_ERROR
return cls.LEN_NEEDMORE
elif firstByte == cls.SD3:
return 14
elif firstByte == cls.SD4:
return 3
return cls.LEN_UNKNOWN
class FpgaPhyMsgCtrl(FpgaPhyMsg):
# SPI control message IDs.
SPICTRL_NOP = 0
SPICTRL_PING = 1
SPICTRL_PONG = 2
SPICTRL_SOFTRESET = 3
SPICTRL_GETSTATUS = 4
SPICTRL_STATUS = 5
SPICTRL_GETBAUD = 6
SPICTRL_BAUD = 7
# Status message data bits.
SPISTAT_PONRESET = 0
SPISTAT_HARDRESET = 1
SPISTAT_SOFTRESET = 2
SPISTAT_TXOVR = 3
SPISTAT_RXOVR = 4
SPISTAT_CTRLCRCERR = 5
CTRL_LEN = 8
def __init__(self, ctrl, ctrlData=0, flg=0):
self.flg = flg | (1 << self.SPI_FLG_CTRL)
self.ctrl = ctrl
self.ctrlData = ctrlData
def toBytes(self):
data = bytearray(8)
data[0] = self.SPI_MS_MAGIC
data[1] = 1 << self.SPI_FLG_CTRL
data[1] |= self.parity(data[1]) << self.SPI_FLG_PARITY
data[2] = self.ctrl & 0xFF
data[3] = (self.ctrlData >> 24) & 0xFF
data[4] = (self.ctrlData >> 16) & 0xFF
data[5] = (self.ctrlData >> 8) & 0xFF
data[6] = self.ctrlData & 0xFF
data[7] = self.crc8(data[2:7])
return data
@classmethod
def fromBytes(cls, data):
if data[0] != cls.SPI_SM_MAGIC:
raise FpgaPhyError("FPGA control message: "
"Invalid MAGC field.")
flg = data[1]
if cls.parity(flg):
raise FpgaPhyError("FPGA control message: "
"Invalid parity bit.")
if not (flg & (1 << cls.SPI_FLG_CTRL)):
raise FpgaPhyError("FPGA control message: "
"CTRL bit is not set.")
ctrl = data[2]
ctrlData = data[3] << 24
ctrlData |= data[4] << 16
ctrlData |= data[5] << 8
ctrlData |= data[6]
crc = data[7]
crcExpected = cls.crc8(data[2:7])
if crc != crcExpected:
raise FpgaPhyError("FPGA control message: "
"CRC error.")
return cls(ctrl, ctrlData, flg)
def __str__(self):
try:
name = {
self.SPICTRL_NOP : "NOP",
self.SPICTRL_PING : "PING",
self.SPICTRL_PONG : "PONG",
self.SPICTRL_SOFTRESET : "SOFTRESET",
self.SPICTRL_GETSTATUS : "GETSTATUS",
self.SPICTRL_STATUS : "STATUS",
self.SPICTRL_GETBAUD : "GETBAUD",
self.SPICTRL_BAUD : "BAUD",
}[self.ctrl]
except KeyError as e:
name = "%02X" % self.ctrl
return "PHYControl(%s, 0x%08X)" % (name, self.ctrlData)
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