# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""A Python library to interact with PCA9555 module for TPM testing.
Background
- PCA9555 is one of two modules on TTCI board
- This library provides methods to interact with PCA9555 programmatically
Dependency
- This library depends on a new C shared library called "libsmogcheck.so".
- In order to run test cases built using this API, one needs a TTCI board
Notes:
- An exception is raised if it doesn't make logical sense to continue program
flow (e.g. I/O error prevents test case from executing)
- An exception is caught and then converted to an error code if the caller
expects to check for error code per API definition
"""
import logging
from autotest_lib.client.common_lib import i2c_slave
# I2C constants
PCA9555_SLV = 0x27 # I2C slave address of PCA9555
# PCA9555 registers
PCA_REG = {
'IN0': 0, # Input Port 0
'IN1': 1, # Input Port 1
'OUT0': 2, # Output Port 0
'OUT1': 3, # Output Port 1
'PI0': 4, # Polarity Inversion 0
'PI1': 5, # Polarity Inversion 1
'CONF0': 6, # Configuration 0
'CONF1': 7, # Configuration 1
}
# Each '1' represents turning on corresponding LED via writing to PCA9555
# Output Port Registers
PCA_BIT_ONE = {
'unalloc_0': 0x01,
'unalloc_1': 0x02,
'unalloc_2': 0x04,
'tpm_i2c': 0x08,
'yellow_led': 0x10,
'main_power': 0x10,
'red_led': 0x20,
'backup_power': 0x20,
'reset': 0x40,
'pp': 0x80,
}
# Constants used to initialize PCA registers
# TODO(tgao): document these bits after stevenh replies
PCA_OUT0_INIT_VAL = 0xff7f
PCA_CONF0_INIT_VAL = 0xc007
class PcaError(Exception):
"""Base class for all errors in this module."""
class PcaController(i2c_slave.I2cSlave):
"""Object to control PCA9555 module on TTCI board."""
def __init__(self):
"""Initialize PCA9555 module on the TTCI board.
Raises:
PcaError: if error initializing PCA9555 module.
"""
super(PcaController, self).__init__()
logging.info('Attempt to initialize PCA9555 module')
try:
self.setSlaveAddress(PCA9555_SLV)
self.writeWord(PCA_REG['OUT0'], PCA_OUT0_INIT_VAL)
self.writeWord(PCA_REG['PI0'], 0)
self.writeWord(PCA_REG['CONF0'], PCA_CONF0_INIT_VAL)
except PcaError, e:
raise PcaError('Error initializing PCA9555: %s' % e)
def setPCAcontrol(self, key, turn_on):
"""Sets specific bit value in Output Port 0 of PCA9555.
Args:
key: a string, valid dict keys in PCA_BIT_ONE.
turn_on: a boolean, true = set bit value to 1.
Returns:
an integer, 0 for success and -1 for error.
"""
logging.info('Attempt to set %r bit to %r', key, turn_on)
try:
byte_read = self.readByte(PCA_REG['OUT0'])
if turn_on:
write_byte = byte_read | PCA_BIT_ONE[key]
else:
write_byte = byte_read & ~PCA_BIT_ONE[key]
self.writeByte(PCA_REG['OUT0'], write_byte)
return 0
except PcaError, e:
logging.error('Error setting PCA9555 Output Port 0: %s', e)
return -1
def _computeLEDmask(self, bit_value, failure, warning):
"""Computes proper bit mask to set LED values.
Args:
<see docstring for TTCI_Set_LEDs()>
Returns:
an integer, 8-bit mask.
Raises:
PcaError: if bit value is out of range.
"""
bit_mask = 0
if bit_value < 0 or bit_value > 15:
raise PcaError('Error: bit_value out of range [0, 15]')
bit_mask = bit_value
if failure:
bit_mask |= 0x20
if warning:
bit_mask |= 0x10
return bit_mask
def getPCAbitStatus(self, key):
"""Gets specific bit value from Output Port 0 of PCA9555.
Args:
key: a string, valid dict keys in PCA_BIT_ONE.
Returns:
an integer, 0 for success and -1 for error.
status: a boolean, True if bit value is '1' and False if bit value
is '0'.
"""
status = False
try:
if PCA_BIT_ONE[key] & self.readByte(PCA_REG['OUT0']):
status = True
return (0, status)
except PcaError, e:
logging.error('Error reading from PCA9555 Output Port 0: %s', e)
return (-1, status)
def setLEDs(self, bit_value, failure, warning):
"""De/activate PCA9555 LEDs.
Mapping of LED to bit values in Output Port 1 (register 3)
(default bit value = 1 <--> LED OFF)
LED 0 (GREEN): O1.0 (mask = 0x01)
LED 1 (GREEN): O1.1 (mask = 0x02)
LED 2 (GREEN): O1.2 (mask = 0x04)
LED 3 (GREEN): O1.3 (mask = 0x08)
LED 4 (YELLOW): O1.4 (mask = 0x10)
LED 5 (RED): O1.5 (mask = 0x20)
To change LED bit values:
1) read byte value from register 3
2) set all 6 lower bits to 1 (LED OFF) by logical OR with 0x3f
3) set appropriate bits to 0 (LED ON) by logical XOR with proper mask
4) write updated byte value to register 3
An example: bit_value=9, failure=False, warning=True
1) read back, say, 0x96, or 1001 0110 (LEDs 0, 3, 5 ON)
2) 0x96 | 0x3f = 0xbf (all LEDs OFF)
3) bit_value=9 -> turn on LEDs 1, 2
failure=False -> keep LED 5 off
warning=True -> turn on LED 4
proper mask = 0001 0110, or 0x16
0xbf ^ 0x16 = 0xa9, or 1010 1001 (LEDs 1, 2, 4 ON)
4) write 0xa9 to register 3
Args:
bit_value: an integer between 0 and 15, representing 4-bit binary
value for green LEDs (i.e. 0~3).
failure: a boolean, true = set red LED value to 0.
warning: a boolean, true = set yellow LED value to 0.
Returns:
an integer, 0 for success and -1 for error.
"""
logging.info('Attempt to set LED values: bit_value=%r, failure=%r, '
'warning=%r', bit_value, failure, warning)
try:
byte_read = self.readByte(PCA_REG['OUT1'])
reset_low6 = byte_read | 0x3f
bit_mask = self._computeLEDmask(bit_value, failure, warning)
write_byte = reset_low6 ^ bit_mask
logging.debug('byte_read = 0x%x, reset_low6 = 0x%x, '
'bit_mask = 0x%x, write_byte = 0x%x',
byte_read, reset_low6, bit_mask, write_byte)
self.writeByte(PCA_REG['OUT1'], write_byte)
return 0
except PcaError, e:
logging.error('Error setting PCA9555 Output Port 0: %s', e)
return -1
def getSwitchStatus(self):
"""Checks status of DIP Switches (2-bit).
Returns:
ret: an integer, error code. 0 = no error.
status: an integer, valid value in range [0, 3].
"""
logging.info('Attempt to read DIP switch status')
ret = -1
status = -1
try:
byte_read = self.readByte(PCA_REG['IN1'])
# Right shift 6-bit to get 2 high-order bits
status = byte_read >> 6
logging.info('DIP switch status = 0x%x', status)
ret = 0
except PcaError, e:
logging.error('No byte read from PCA9555 Input Port 1: %s', e)
return (ret, status)
def getLEDstatus(self):
"""Checks LED status.
Returns:
ret: an integer, 0 for success and -1 for error.
bit_value: an integer between 0 and 15, representing 4-bit binary
value for green LEDs (i.e. 0~3). Default: -1.
failure: a boolean, true = red LED has value 0. Default: False.
warning: a boolean, true = yellow LED has value 0. Default: False.
"""
ret = -1
bit_value = -1
failure = False
warning = False
try:
byte_read = self.readByte(PCA_REG['OUT1'])
if not (byte_read | PCA_BIT_ONE['red_led']):
failure = True
if not (byte_read | PCA_BIT_ONE['yellow_led']):
warning = True
bit_value = byte_read & 0xf # Get lower 4-bit value
logging.info('LED bit_value = %r, failure = %r, warning = %r',
bit_value, failure, warning)
ret = 0
except PcaError, e:
logging.error('No byte read from PCA9555 Output Port 1: %s', e)
return (ret, bit_value, failure, warning)