diff options
Diffstat (limited to 'meta-facebook/meta-wedge/recipes-wedge/fbutils/files/at93c46.py')
| -rw-r--r-- | meta-facebook/meta-wedge/recipes-wedge/fbutils/files/at93c46.py | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/meta-facebook/meta-wedge/recipes-wedge/fbutils/files/at93c46.py b/meta-facebook/meta-wedge/recipes-wedge/fbutils/files/at93c46.py new file mode 100644 index 0000000..368b807 --- /dev/null +++ b/meta-facebook/meta-wedge/recipes-wedge/fbutils/files/at93c46.py @@ -0,0 +1,260 @@ +# Copyright 2004-present Facebook. All rights reserved. + +import subprocess +import struct +import sys + +class VerboseLogger: + def __init__(self, verbose=False): + self.verbose = verbose + + def _verbose_print(self, caption, bytestream=None): + ''' + Print a bytestream to stdout if verbose is enabled. + ''' + if self.verbose: + if bytestream is not None: + sys.stderr.write("{}: {}\n".format(caption, " ".join(['{:02X}'.format(ord(x)) for x in bytestream]))) + else: + sys.stderr.write("{}\n".format(caption)) + +class AT93C46SPI(VerboseLogger): + '''The class to access AT93C46 through SPI intf''' + SPI_CMD = 'spi-bb' + + def __init__(self, bus_width, gpio_cs, gpio_ck, gpio_do, gpio_di, + verbose=False): + if bus_width != 8 and bus_width != 16: + raise Exception("Invalid bus width for AT93C46!") + + self.bus_width = bus_width + self.gpio_cs = gpio_cs + self.gpio_ck = gpio_ck + self.gpio_do = gpio_do + self.gpio_di = gpio_di + self.verbose = verbose + + self.addr_bits = 6 if self.bus_width == 16 else 7 + self.addr_mask = 0x3F if self.bus_width == 16 else 0x7F + + def __shift(self, bytestream, value): + ''' + Shift an entire byte stream by value bits. + ''' + binary = "".join(['{:08b}'.format(ord(x)) for x in bytestream]) + if value > 0: + binary = binary[value:] + '0' * value + else: + binary = '0' * (-value) + binary[:value] + return "".join([chr(int(binary[x:x+8],2)) for x in range(0, len(binary), 8)]) + + def __io(self, op, addr, data=None): + ''' + Perform an IO operation against the EEPROM + ''' + write_bits = self.addr_bits + 3 + if data is not None: + # If giving data, we are doing a write command so + # no need to read any data. + write_bits = write_bits + self.bus_width + read_bits = 0 + else: + # If not giving data, we are doing either a read + # command or a set command, so read the result. + # We pad with an extra bit due to a dummy bit introduced + # by a delay for address decoding on chip. + read_bits = self.addr_bits + 4 + self.bus_width + + # Format the command itself + cmd_loc = 6 if self.bus_width == 16 else 7 + instruction = addr & self.addr_mask + instruction = instruction | ((0x4 | (op & 0x3)) << cmd_loc) + if data is not None: + if self.bus_width == 16: + write_data = struct.pack(">HH", instruction, data & 0xFFFF) + else: + write_data = struct.pack(">HB", instruction, data & 0xFF) + else: + write_data = struct.pack(">H", instruction) + write_data = self.__shift(write_data, 16 - (cmd_loc + 3)) + + self._verbose_print("Write data", write_data) + + # Run the command with the bitbang driver + if read_bits > 0: + data_portion = "-r {} -w {}".format(read_bits, write_bits) + else: + data_portion = "-w {}".format(write_bits) + + cmd = "{} -s {} -c {} -o {} -i {} -b {}".format( + self.SPI_CMD, self.gpio_cs, self.gpio_ck, self.gpio_do, + self.gpio_di, data_portion + ) + + self._verbose_print("Command: {}".format(cmd)) + + out = subprocess.Popen(cmd.split(), + stdout=subprocess.PIPE, + stdin = subprocess.PIPE)\ + .communicate(input=write_data) + + # Format the response + read_data = self.__shift(out[0], cmd_loc + 4) + if self.bus_width == 16: + read_data = read_data[:2] + self._verbose_print("Read data", read_data) + return struct.unpack(">H", read_data)[0] + else: + read_data = read_data[:1] + self._verbose_print("Read data", read_data) + return struct.unpack(">B", read_data)[0] + + def read(self, addr): + return self.__io(0x2, addr) + + def ewen(self): + self.__io(0x0, 0x3 << (self.addr_bits - 2)) + + def erase(self, addr): + self.__io(0x3, addr) + + def write(self, addr, data): + self.__io(0x1, addr, data) + + def eral(self): + self.__io(0x0, 0x2 << (self.addr_bits - 2)) + + def wral(self, data): + self.__io(0x0, 0x1 << (self.addr_bits - 2), data) + + def ewds(self): + self.__io(0x0, 0x0) + +class AT93C46(VerboseLogger): + ''' + The class which handles accessing memory on the AT93C46 chip. + ''' + AT93C46_MEMORY_SIZE = 128 + + def __init__(self, bus_width, gpio_cs, gpio_ck, gpio_do, gpio_di, + byte_swap, verbose=False): + self.bus_width = bus_width + self.verbose = verbose + self.byte_swap = byte_swap + + self.spi = AT93C46SPI(bus_width=bus_width, gpio_cs=gpio_cs, + gpio_ck=gpio_ck, gpio_do=gpio_do, + gpio_di=gpio_di, verbose=verbose) + + def __swap(self, value): + ''' + Swap bytes for a 16-bit integer if instructed to do so. + ''' + if self.bus_width == 16: + if self.byte_swap: + return ((value >> 8) & 0xFF) | ((value << 8) & 0xFF00) + else: + return value + else: + return value + + def erase(self, offset=None, limit=None): + ''' + Erase the chip. + ''' + if offset is None: + offset = 0 + if limit is None: + limit = self.AT93C46_MEMORY_SIZE + + if offset < 0 or offset + limit > self.AT93C46_MEMORY_SIZE: + raise Exception("Erase would be out of bounds!") + if self.bus_width == 16 and \ + ((offset & 1) != 0 or ((offset + limit) & 1) != 0): + raise Exception("Erase can't start or end on odd boundary in 16-bit mode!") + + if offset == 0 and limit == self.AT93C46_MEMORY_SIZE: + # Special case when we are erasing the entire chip + self.spi.ewen() + self.spi.eral() + self.spi.ewds() + + self._verbose_print("Erased entire chip") + else: + # Regular case + if self.bus_width == 16: + real_offset = offset / 2 + real_limit = limit / 2 + else: + real_offset = offset + real_limit = limit + + self.spi.ewen() + for addr in range(real_offset, real_offset + real_limit): + self.spi.erase(addr) + self.spi.ewds() + + self._verbose_print("Erased {} bytes from offset {}".format(limit, offset)) + + def read(self, offset=None, limit=None): + ''' + Read the chip into a memory buffer. + ''' + if offset is None: + offset = 0 + if limit is None: + limit = self.AT93C46_MEMORY_SIZE + + if offset < 0 or offset + limit > self.AT93C46_MEMORY_SIZE: + raise Exception("Read would be out of bounds!") + if self.bus_width == 16 and \ + ((offset & 1) != 0 or ((offset + limit) & 1) != 0): + raise Exception("Read can't start or end on odd boundary in 16-bit mode!") + + output = "" + if self.bus_width == 16: + real_offset = offset / 2 + real_limit = limit / 2 + pack_instruction = "=H" + else: + real_offset = offset + real_offset + pack_instruction = "=B" + + for addr in range(real_offset, real_offset + real_limit): + output = output + struct.pack(pack_instruction, self.__swap(self.spi.read(addr))) + + self._verbose_print("Read {} bytes from offset {}".format(limit, offset), output) + + return output + + def write(self, data, offset=None): + ''' + Write a memory buffer to the chip. + ''' + if offset is None: + offset = 0 + + if offset < 0 or offset + len(data) > self.AT93C46_MEMORY_SIZE: + raise Exception("Write would be out of bounds!") + if self.bus_width == 16 and \ + ((offset & 1) != 0 or ((offset + len(data)) & 1) != 0): + raise Exception("Write can't start or end on odd boundary in 16-bit mode!") + + if self.bus_width == 16: + offset_divisor = 2 + pack_instruction = "=H" + else: + offset_divisor = 1 + pack_instruction = "=B" + + self.spi.ewen() + for addr in range(offset, offset + len(data), offset_divisor): + actual_addr = addr / offset_divisor + value = self.__swap(struct.unpack(pack_instruction, data[(addr - offset):(addr - offset) + offset_divisor])[0]) + + self.spi.erase(actual_addr) + self.spi.write(actual_addr, value) + self.spi.ewds() + + self._verbose_print("Wrote {} bytes from offset {}".format(len(data), offset), data) |
