| /* |
| // Copyright (c) 2022 Equinix, Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| */ |
| |
| #pragma once |
| |
| #include <cstdint> |
| #include <cstdio> |
| #include <functional> |
| #include <map> |
| #include <optional> |
| #include <utility> |
| |
| extern "C" |
| { |
| // For I2C_SMBUS_BLOCK_MAX |
| #include <linux/i2c.h> |
| } |
| |
| // A function to read up to I2C_SMBUS_BLOCK_MAX bytes of FRU data. Returns |
| // negative on error, or the number of bytes read otherwise, which may be (but |
| // is not guaranteed to be) less than len if the read would go beyond the end |
| // of the FRU. |
| using ReadBlockFunc = |
| std::function<int64_t(off_t offset, size_t len, uint8_t* outbuf)>; |
| |
| // A caching wrapper around a ReadBlockFunc |
| class FRUReader |
| { |
| public: |
| explicit FRUReader(ReadBlockFunc readFunc) : readFunc(std::move(readFunc)) |
| {} |
| // The ::read() operation here is analogous to ReadBlockFunc (with the same |
| // return value semantics), but is not subject to SMBus block size |
| // limitations; it can read as much data as needed in a single call. |
| ssize_t read(off_t start, size_t len, uint8_t* outbuf); |
| |
| private: |
| static constexpr size_t cacheBlockSize = 32; |
| static_assert(cacheBlockSize <= I2C_SMBUS_BLOCK_MAX); |
| using CacheBlock = std::array<uint8_t, cacheBlockSize>; |
| |
| // indexed by block number (byte number / block size) |
| using Cache = std::map<uint32_t, CacheBlock>; |
| |
| ReadBlockFunc readFunc; |
| Cache cache; |
| |
| // byte offset of the end of the FRU (if readFunc has reported it) |
| std::optional<size_t> eof; |
| }; |