| # Copyright (c) 2013 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. |
| """Driver for board config controls pca95xx. |
| |
| Either: |
| tca6416 compatible: |
| PCA9534 -- 4bit GPIO expander |
| PCA9537 -- 8bit GPIO expander |
| pca9500 compatible: |
| PCA9500 -- 8bit GPIO expander + EEPROM |
| """ |
| import pca9500 |
| import pca9537 |
| |
| def pca95xx(interface, params): |
| """Method to determine real driver object to instantiate. |
| |
| Returns: |
| pca95xx instance that has inherited from either pc9500 or pca9537 driver. |
| """ |
| |
| def determine_device(interface, slave): |
| """Determine which i2c device is present. |
| |
| There are number of these I2c->GPIO expanders that all share similar |
| functionality and unfortunately slave addresses. Two such are the pca9500 |
| (NXP) and pca953x (TI) devices. They don't have any ID registers to |
| formally distiguish them but the pca9500 does have an EEPROM at + 0x30 from |
| the base slave address which serves as a reasonable identifier. |
| |
| TODO(crbug.com/233747): In case of I2c interface via ftdi (libftdii2c.so) |
| there is no simple way inside python to disable stdout if it is being |
| printed from libc. For that reason, when pca9537 device is encountered |
| you'll see the following benign error during hwinit: |
| -E- :: Slave 0x56 failed wr_rd with fic->error:0 err:2 |
| |
| Returns: |
| driver object pca9500 if EEPROM identified else pca9537. |
| """ |
| eeprom_slave = 0x30 + slave |
| |
| try: |
| interface.wr_rd(eeprom_slave, [], 1) |
| base = pca9500.pca9500 |
| except Exception: |
| base = pca9537.pca9537 |
| |
| return base |
| |
| slave = int(params['slv'], 0) |
| base = determine_device(interface, slave) |
| |
| return base(interface, params) |
