mtd_dev.h

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/*
 * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
 * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
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 *    of conditions and the following disclaimer in the documentation and/or other materials
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#ifndef __MTD_DEV_H__
#define __MTD_DEV_H__
 
#include "los_typedef.h"
 
/**
 * @file mtd_dev.h
 * @verbatim
    MTD，Memory Technology Device即内存技术设备
    Linux系统中采用MTD来管理不同类型的Flash芯片，包括NandFlash和NorFlash
    NAND型和NOR型Flash在进行写入和擦除时都需要MTD（Memory Technology Drivers，MTD已集成在Flash芯片内部，
    它是对Flash进行操作的接口），这是它们的共同特点；但在NOR型Flash上运行代码不需要任何的软件支持，
    而在NAND型Flash上进行同样操作时，通常需要驱动程序，即内存技术驱动程序MTD。
 
    NOR型Flash采用的SRAM接口，提供足够的地址引脚来寻址，可以很容易的存取其片内的每一个字节；
    NAND型Flash使用复杂的I/O口来串行的存取数据，各个产品或厂商的方法可能各不相同，通常是采用8个I/O引脚
    来传送控制、地址、数据信息。
 
    NAND型Flash具有较高的单元密度，容量可以做得比较大，加之其生产过程更为简单，价格较低；NOR型Flash占据了容量
    为1～16MB闪存市场的大部分，而NAND型Flash只是用在8～128MB的产品中，这也说明NOR主要用在代码存储介质中，
    NAND适合数据存储。 
 * @endverbatim 
 * @brief 
 */
#define MTD_NORFLASH        3   ///< 存储空间一般比较小，但它可以不用初始化，可以在其内部运行程序，一般在其存储一些初始化内存的固件代码；
#define MTD_NANDFLASH       4
#define MTD_DATAFLASH       6
#define MTD_MLCNANDFLASH    8
 
/**
 * @brief
 * @verbatim
    扇区是对硬盘而言，而块是对文件系统而言
    文件系统不是一个扇区一个扇区的来读数据，一个扇区512个字节,太慢了，所以有了block（块）的概念，
    文件系统是一个块一个块的读取的，block才是文件存取的最小单位。
    一个block是4K，即:文件系统中1个块是由连续的8个扇区组成
 * @endverbatim  
 */
struct MtdNorDev {
    unsigned long blockSize;    ///< 块大小,不用猜也知道,是4K,和内存的页等同,如此方便置换
    unsigned long blockStart;   ///< 开始块索引
    unsigned long blockEnd;     ///< 结束块索引
};
 
/// flash MTD 层 描述符
struct MtdDev {
    VOID *priv;
    UINT32 type;
 
    UINT64 size;
    UINT32 eraseSize; ///< 4K, 跟PAGE_CACHE_SIZE对应
    
    int (*erase)(struct MtdDev *mtd, UINT64 start, UINT64 len, UINT64 *failAddr);///< 擦除flash操作
    int (*read)(struct MtdDev *mtd, UINT64 start, UINT64 len, const char *buf);  ///< 读操作
    int (*write)(struct MtdDev *mtd, UINT64 start, UINT64 len, const char *buf); ///< 写操作
};
 
 
#endif /* __MTD_DEV_H__ */