mbed-os/features/storage/blockdevice/ExhaustibleBlockDevice.h

/*
 * Copyright (c) 2018-2019, Arm Limited and affiliates.
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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.
 */

/** \addtogroup storage */
/** @{*/

#ifndef MBED_EXHAUSTIBLE_BLOCK_DEVICE_H
#define MBED_EXHAUSTIBLE_BLOCK_DEVICE_H

#include "BlockDevice.h"

namespace mbed {

/** Heap backed block device which simulates failures
 *
 * Similar to heap block device but sectors wear out and are no longer programmable
 * after a configurable number of cycles.
 *
 */
class ExhaustibleBlockDevice : public BlockDevice {
public:
    /** Lifetime of the block device
     *
     * @param bd            Block device to back the ExhaustibleBlockDevice
     * @param erase_cycles  Number of erase cycles before failure
     */
    ExhaustibleBlockDevice(BlockDevice *bd, uint32_t erase_cycles);
    virtual ~ExhaustibleBlockDevice();

    /**
     * Get the number of erase cycles remaining on a block
     *
     * @param addr      Any address in the block being queried for erase cycles
     * @return          Number of erase cycles remaining
     */
    uint32_t get_erase_cycles(bd_addr_t addr) const;

    /**
     * Set the number of erase cycles before failure
     *
     * @param addr      Any address in the block being queried for erase cycles
     * @param cycles    Erase cycles before the block malfunctions
     */
    void set_erase_cycles(bd_addr_t addr, uint32_t cycles);

    /** Initialize a block device
     *
     *  @return         0 on success or a negative error code on failure
     */
    virtual int init();

    /** Deinitialize a block device
     *
     *  @return         0 on success or a negative error code on failure
     */
    virtual int deinit();

    /** Ensure data on storage is in sync with the driver
     *
     *  @return         0 on success or a negative error code on failure
     */
    virtual int sync();

    /** Read blocks from a block device
     *
     *  @param buffer   Buffer to read blocks into
     *  @param addr     Address of block to begin reading from
     *  @param size     Size to read in bytes, must be a multiple of read block size
     *  @return         0 on success, negative error code on failure
     */
    virtual int read(void *buffer, bd_addr_t addr, bd_size_t size);

    /** Program blocks to a block device
     *
     *  The blocks must have been erased prior to being programmed
     *
     *  @param buffer   Buffer of data to write to blocks
     *  @param addr     Address of block to begin writing to
     *  @param size     Size to write in bytes, must be a multiple of program block size
     *  @return         0 on success, negative error code on failure
     */
    virtual int program(const void *buffer, bd_addr_t addr, bd_size_t size);

    /** Erase blocks on a block device
     *
     *  The state of an erased block is undefined until it has been programmed,
     *  unless get_erase_value returns a non-negative byte value
     *
     *  @param addr     Address of block to begin erasing
     *  @param size     Size to erase in bytes, must be a multiple of erase block size
     *  @return         0 on success, negative error code on failure
     */
    virtual int erase(bd_addr_t addr, bd_size_t size);

    /** Get the size of a readable block
     *
     *  @return         Size of a readable block in bytes
     */
    virtual bd_size_t get_read_size() const;

    /** Get the size of a programmable block
     *
     *  @return         Size of a programmable block in bytes
     */
    virtual bd_size_t get_program_size() const;

    /** Get the size of an erasable block
     *
     *  @return         Size of an erasable block in bytes
     */
    virtual bd_size_t get_erase_size() const;

    /** Get the size of an erasable block given address
     *
     *  @param addr     Address within the erasable block
     *  @return         Size of an erasable block in bytes
     *  @note Must be a multiple of the program size
     */
    virtual bd_size_t get_erase_size(bd_addr_t addr) const;

    /** Get the value of storage when erased
     *
     *  If get_erase_value returns a non-negative byte value, the underlying
     *  storage is set to that value when erased, and storage containing
     *  that value can be programmed without another erase.
     *
     *  @return         The value of storage when erased, or -1 if you can't
     *                  rely on the value of erased storage
     */
    virtual int get_erase_value() const;

    /** Get the total size of the underlying device
     *
     *  @return         Size of the underlying device in bytes
     */
    virtual bd_size_t size() const;

    /** Get the BlockDevice class type.
     *
     *  @return         A string represent the BlockDevice class type.
     */
    virtual const char *get_type() const;

private:
    BlockDevice *_bd;
    uint32_t *_erase_array;
    uint32_t _erase_cycles;
    uint32_t _init_ref_count;
    bool _is_initialized;
};

} // namespace mbed

// Added "using" for backwards compatibility
#ifndef MBED_NO_GLOBAL_USING_DIRECTIVE
using mbed::ExhaustibleBlockDevice;
#endif

#endif

/** @}*/