BlockDevice.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2017 ARM Limited
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 
00017 #ifndef MBED_BLOCK_DEVICE_H
00018 #define MBED_BLOCK_DEVICE_H
00019 
00020 #include <stdint.h>
00021 
00022 
00023 /** Enum of standard error codes
00024  *
00025  *  @enum bd_error
00026  */
00027 enum bd_error {
00028     BD_ERROR_OK                 = 0,     /*!< no error */
00029     BD_ERROR_DEVICE_ERROR       = -4001, /*!< device specific error */
00030 };
00031 
00032 /** Type representing the address of a specific block
00033  */
00034 typedef uint64_t bd_addr_t;
00035 
00036 /** Type representing a quantity of 8-bit bytes
00037  */
00038 typedef uint64_t bd_size_t;
00039 
00040 
00041 /** A hardware device capable of writing and reading blocks
00042  */
00043 class BlockDevice
00044 {
00045 public:
00046     /** Lifetime of a block device
00047      */
00048     virtual ~BlockDevice() {};
00049 
00050     /** Initialize a block device
00051      *
00052      *  @return         0 on success or a negative error code on failure
00053      */
00054     virtual int init() = 0;
00055 
00056     /** Deinitialize a block device
00057      *
00058      *  @return         0 on success or a negative error code on failure
00059      */
00060     virtual int deinit() = 0;
00061 
00062     /** Ensure data on storage is in sync with the driver
00063      *
00064      *  @return         0 on success or a negative error code on failure
00065      */
00066     virtual int sync()
00067     {
00068         return 0;
00069     }
00070 
00071     /** Read blocks from a block device
00072      *
00073      *  If a failure occurs, it is not possible to determine how many bytes succeeded
00074      *
00075      *  @param buffer   Buffer to write blocks to
00076      *  @param addr     Address of block to begin reading from
00077      *  @param size     Size to read in bytes, must be a multiple of read block size
00078      *  @return         0 on success, negative error code on failure
00079      */
00080     virtual int read(void *buffer, bd_addr_t addr, bd_size_t size) = 0;
00081 
00082     /** Program blocks to a block device
00083      *
00084      *  The blocks must have been erased prior to being programmed
00085      *
00086      *  If a failure occurs, it is not possible to determine how many bytes succeeded
00087      *
00088      *  @param buffer   Buffer of data to write to blocks
00089      *  @param addr     Address of block to begin writing to
00090      *  @param size     Size to write in bytes, must be a multiple of program block size
00091      *  @return         0 on success, negative error code on failure
00092      */
00093     virtual int program(const void *buffer, bd_addr_t addr, bd_size_t size) = 0;
00094 
00095     /** Erase blocks on a block device
00096      *
00097      *  The state of an erased block is undefined until it has been programmed,
00098      *  unless get_erase_value returns a non-negative byte value
00099      *
00100      *  @param addr     Address of block to begin erasing
00101      *  @param size     Size to erase in bytes, must be a multiple of erase block size
00102      *  @return         0 on success, negative error code on failure
00103      */
00104     virtual int erase(bd_addr_t addr, bd_size_t size)
00105     {
00106         return 0;
00107     }
00108 
00109     /** Mark blocks as no longer in use
00110      *
00111      *  This function provides a hint to the underlying block device that a region of blocks
00112      *  is no longer in use and may be erased without side effects. Erase must still be called
00113      *  before programming, but trimming allows flash-translation-layers to schedule erases when
00114      *  the device is not busy.
00115      *
00116      *  @param addr     Address of block to mark as unused
00117      *  @param size     Size to mark as unused in bytes, must be a multiple of erase block size
00118      *  @return         0 on success, negative error code on failure
00119      */
00120     virtual int trim(bd_addr_t addr, bd_size_t size)
00121     {
00122         return 0;
00123     }
00124 
00125     /** Get the size of a readable block
00126      *
00127      *  @return         Size of a readable block in bytes
00128      */
00129     virtual bd_size_t get_read_size() const = 0;
00130 
00131     /** Get the size of a programable block
00132      *
00133      *  @return         Size of a programable block in bytes
00134      *  @note Must be a multiple of the read size
00135      */
00136     virtual bd_size_t get_program_size() const = 0;
00137 
00138     /** Get the size of a eraseable block
00139      *
00140      *  @return         Size of a eraseable block in bytes
00141      *  @note Must be a multiple of the program size
00142      */
00143     virtual bd_size_t get_erase_size() const
00144     {
00145         return get_program_size();
00146     }
00147 
00148     /** Get the value of storage when erased
00149      *
00150      *  If get_erase_value returns a non-negative byte value, the underlying
00151      *  storage is set to that value when erased, and storage containing
00152      *  that value can be programmed without another erase.
00153      *
00154      *  @return         The value of storage when erased, or -1 if you can't
00155      *                  rely on the value of erased storage
00156      */
00157     virtual int get_erase_value() const
00158     {
00159         return -1;
00160     }
00161 
00162     /** Get the total size of the underlying device
00163      *
00164      *  @return         Size of the underlying device in bytes
00165      */
00166     virtual bd_size_t size() const = 0;
00167 
00168     /** Convenience function for checking block read validity
00169      *
00170      *  @param addr     Address of block to begin reading from
00171      *  @param size     Size to read in bytes
00172      *  @return         True if read is valid for underlying block device
00173      */
00174     bool is_valid_read(bd_addr_t addr, bd_size_t size) const
00175     {
00176         return (
00177             addr % get_read_size() == 0 &&
00178             size % get_read_size() == 0 &&
00179             addr + size <= this->size());
00180     }
00181 
00182     /** Convenience function for checking block program validity
00183      *
00184      *  @param addr     Address of block to begin writing to
00185      *  @param size     Size to write in bytes
00186      *  @return         True if program is valid for underlying block device
00187      */
00188     bool is_valid_program(bd_addr_t addr, bd_size_t size) const
00189     {
00190         return (
00191             addr % get_program_size() == 0 &&
00192             size % get_program_size() == 0 &&
00193             addr + size <= this->size());
00194     }
00195 
00196     /** Convenience function for checking block erase validity
00197      *
00198      *  @param addr     Address of block to begin erasing
00199      *  @param size     Size to erase in bytes
00200      *  @return         True if erase is valid for underlying block device
00201      */
00202     bool is_valid_erase(bd_addr_t addr, bd_size_t size) const
00203     {
00204         return (
00205             addr % get_erase_size() == 0 &&
00206             size % get_erase_size() == 0 &&
00207             addr + size <= this->size());
00208     }
00209 };
00210 
00211 
00212 #endif