I2CEEBlockDevice.cpp

00001 /* Simple access class for I2C EEPROM chips like Microchip 24LC
00002  * Copyright (c) 2015 Robin Hourahane
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #include "I2CEEBlockDevice.h"
00017 #include "rtos/ThisThread.h"
00018 using namespace mbed;
00019 
00020 #define I2CEE_TIMEOUT 10000
00021 
00022 
00023 I2CEEBlockDevice::I2CEEBlockDevice(
00024     PinName sda, PinName scl, uint8_t addr,
00025     bd_size_t size, bd_size_t block, int freq)
00026     : _i2c_addr(addr), _size(size), _block(block)
00027 {
00028     _i2c = new (_i2c_buffer) I2C(sda, scl);
00029     _i2c->frequency(freq);
00030 }
00031 
00032 I2CEEBlockDevice::I2CEEBlockDevice(
00033     I2C *i2c_obj, uint8_t addr,
00034     bd_size_t size, bd_size_t block)
00035     : _i2c_addr(addr), _size(size), _block(block)
00036 {
00037     _i2c = i2c_obj;
00038 }
00039 I2CEEBlockDevice::~I2CEEBlockDevice()
00040 {
00041     if (_i2c == (I2C *)_i2c_buffer) {
00042         _i2c->~I2C();
00043     }
00044 }
00045 
00046 int I2CEEBlockDevice::init()
00047 {
00048     return _sync();
00049 }
00050 
00051 int I2CEEBlockDevice::deinit()
00052 {
00053     return 0;
00054 }
00055 
00056 int I2CEEBlockDevice::read(void *buffer, bd_addr_t addr, bd_size_t size)
00057 {
00058     // Check the address and size fit onto the chip.
00059     MBED_ASSERT(is_valid_read(addr, size));
00060 
00061     _i2c->start();
00062 
00063     if (!_i2c->write(_i2c_addr | 0) ||
00064             !_i2c->write((char)(addr >> 8)) ||
00065             !_i2c->write((char)(addr & 0xff))) {
00066         return BD_ERROR_DEVICE_ERROR;
00067     }
00068 
00069     _i2c->stop();
00070 
00071     if (_i2c->read(_i2c_addr, static_cast<char *>(buffer), size) < 0) {
00072         return BD_ERROR_DEVICE_ERROR;
00073     }
00074 
00075     return 0;
00076 }
00077 
00078 int I2CEEBlockDevice::program(const void *buffer, bd_addr_t addr, bd_size_t size)
00079 {
00080     // Check the addr and size fit onto the chip.
00081     MBED_ASSERT(is_valid_program(addr, size));
00082 
00083     // While we have some more data to write.
00084     while (size > 0) {
00085         uint32_t off = addr % _block;
00086         uint32_t chunk = (off + size < _block) ? size : (_block - off);
00087 
00088         _i2c->start();
00089 
00090         if (!_i2c->write(_i2c_addr | 0) ||
00091                 !_i2c->write((char)(addr >> 8)) ||
00092                 !_i2c->write((char)(addr & 0xff))) {
00093             return BD_ERROR_DEVICE_ERROR;
00094         }
00095 
00096         for (unsigned i = 0; i < chunk; i++) {
00097             _i2c->write(static_cast<const char *>(buffer)[i]);
00098         }
00099 
00100         _i2c->stop();
00101 
00102         int err = _sync();
00103 
00104         if (err) {
00105             return err;
00106         }
00107 
00108         addr += chunk;
00109         size -= chunk;
00110         buffer = static_cast<const char *>(buffer) + chunk;
00111     }
00112 
00113     return 0;
00114 }
00115 
00116 int I2CEEBlockDevice::erase(bd_addr_t addr, bd_size_t size)
00117 {
00118     // No erase needed
00119     return 0;
00120 }
00121 
00122 int I2CEEBlockDevice::_sync()
00123 {
00124     // The chip doesn't ACK while writing to the actual EEPROM
00125     // so loop trying to do a zero byte write until it is ACKed
00126     // by the chip.
00127     for (int i = 0; i < I2CEE_TIMEOUT; i++) {
00128         if (_i2c->write(_i2c_addr | 0, 0, 0) < 1) {
00129             return 0;
00130         }
00131 
00132         rtos::ThisThread::sleep_for(1);
00133     }
00134 
00135     return BD_ERROR_DEVICE_ERROR;
00136 }
00137 
00138 bd_size_t I2CEEBlockDevice::get_read_size() const
00139 {
00140     return 1;
00141 }
00142 
00143 bd_size_t I2CEEBlockDevice::get_program_size() const
00144 {
00145     return 1;
00146 }
00147 
00148 bd_size_t I2CEEBlockDevice::get_erase_size() const
00149 {
00150     return 1;
00151 }
00152 
00153 bd_size_t I2CEEBlockDevice::size() const
00154 {
00155     return _size;
00156 }
00157 
00158 const char *I2CEEBlockDevice::get_type() const
00159 {
00160     return "I2CEE";
00161 }