SPI NAND

SPI NAND 是挂载在 SPI 总线上的 MTD 设备，初始化 probe 在 MTD 设备第一次被使用时触发。 调用 mtd_probe_devices() 是对 MTD 设备驱动初始化的常用方式。

mtd_probe_devices(void)
|-> mtd_probe_uclass_mtd_devs(void) // drivers/mtd/mtd_uboot.c
    |   // 通过 while 循环，逐个 UCLASS_MTD 设备 find
    |-> uclass_find_device(UCLASS_MTD, idx, &dev)
    |-> mtd_probe(dev)
        |-> device_probe(dev)
            |-> spinand_probe(dev) // drivers/mtd/nand/spi/core.c
                |   // spinand = dev_get_priv(dev);
                |   // slave = dev_get_parent_priv(dev);
                |   // mtd = dev_get_uclass_priv(dev);
                |   // nand = &spinand->base;
                |   //
                |   // spinand->slave = slave;
                |
                |-> spinand_init(spinand);
                |   |-> spinand_detect(spinand);
                |   |   |-> spinand_manufacturer_detect(spinand);
                |   |       |                 // drivers/mtd/nand/spi/core.c
                |   |       |-> spinand_manufacturers[i]->ops->detect(spinand);
                |   |           // 尝试厂商的 detect 函数
                |   |
                |   |-> spinand_manufacturer_init(spinand);
                |   |-> nanddev_init(nand, &spinand_ops, THIS_MODULE);
                |   |   |                         // drivers/mtd/nand/core.c
                |   |   |   // mtd->type = memorg->bits_per_cell == 1 ?
                |   |   |   //          MTD_NANDFLASH : MTD_MLCNANDFLASH;
                |   |   |
                |   |   |-> nanddev_bbt_init(nand) // drivers/mtd/nand/bbt.c
                |   |       // 此处仅申请标记坏块的 Cache 空间，不做坏块检查
                |   |
                |   |-> // mtd = spinand->base.mtd
                |       //
                |       // mtd->_read_oob = spinand_mtd_read;
                |       // mtd->_write_oob = spinand_mtd_write;
                |       // mtd->_block_isbad = spinand_mtd_block_isbad;
                |       // mtd->_block_markbad = spinand_mtd_block_markbad;
                |       // mtd->_block_isreserved = spinand_mtd_block_isreserved;
                |       // mtd->_erase = spinand_mtd_erase;
                |       //
                |       // 此处完成 mtd 的初始化
                |
                |-> add_mtd_device(mtd);
                    |-> idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
                            // 添加到 mtd_idr 列表中

NAND 存储设备在访问前，通常要做一次坏块检查。U-Boot 中在添加分区的时候进行检查坏块：

do_mtd_list();  // cmd/mtd.c
|-> mtd_probe_devices(); // drivers/mtd/mtd_uboot.c
    |-> add_mtd_partitions(); // drivers/mtd/mtdpart.c
        |-> allocate_partition(); // drivers/mtd/mtdpart.c
        |   |   // 这里做坏块统计
        |   |-> mtd_block_isbad(); // drivers/mtd/mtdcore.c
        |       |-> mtd->_block_isbad(mtd, ofs);
        |           spinand_mtd_block_isbad(); // drivers/mtd/nand/spi/core.c
        |           |-> nanddev_isbad(); // drivers/mtd/nand/core.c
        |               |-> spinand_isbad(); // drivers/mtd/nand/spi/core.c
        |                   |-> spinand_read_page();
        |
        |-> add_mtd_device(slave); // drivers/mtd/mtdcore.c

上层应用，如 mtd 命令和 UBI，通过 mtd_read / mtd_write API 进行读写等操作。

mtd_read
|-> mtd->_read_oob(mtd, from, &ops);
    part_read_oob(mtd, from, &ops); // drivers/mtd/mtdpart.c
    |-> mtd->parent->_read_oob(mtd->parent, from + mtd->offset, ops);
        spinand_mtd_read(mtd, from, &ops); // drivers/mtd/nand/spi/core.c
        |-> spinand_read_page(spinand, &iter.req, enable_ecc);
            |-> spinand_load_page_op(spinand, req);
            |   |-> spi_mem_exec_op(spinand->slave, &op); // drivers/spi/spi-mem.c
            |       |-> ops->mem_ops->exec_op(slave, op);
            |           aic_spi_mem_exec_op(slave, op);
            |           // drivers/spi/artinchip_spi.c
            |
            |-> spinand_read_from_cache_op(spinand, req);
                |-> spi_mem_exec_op(spinand->slave, &op);
                    |-> ops->mem_ops->exec_op(slave, op);
                        aic_spi_mem_exec_op(slave, op);
                        // drivers/spi/artinchip_spi.c

mtd_write
|-> mtd->_write_oob(mtd, to, &ops);
    part_write_oob(mtd, to, &ops); // drivers/mtd/mtdpart.c
    |-> mtd->parent->_write_oob(mtd->parent, to + mtd->offset, ops);
        spinand_mtd_write(mtd, to, &ops);
        |-> spinand_write_page(spinand, &iter.req);
            |-> spinand_write_enable_op(spinand);
            |-> spinand_write_to_cache_op(spinand, req);
            |-> spinand_program_op(spinand, req);
                |-> spi_mem_exec_op(spinand->slave, &op); // drivers/spi/spi-mem.c
                    |-> ops->mem_ops->exec_op(slave, op);
                        aic_spi_mem_exec_op(slave, op);
                        // drivers/spi/artinchip_spi.c