主要是设置struct mtd_partition中的mask_flags标志位
具体含义为：
1. master MTD flags to mask out for this partition
2. contains flags that have to be masked (removed) from the
master MTD flag set for the corresponding MTD partition.
凡是置1的bit,相应属性将被惕掉,比如设置为MTD_WRITEABLE,那么表示剔出读写,
因此该mtd分区将只有读权限[luther.gliethttp].
static struct platform_driver pxa3xx_nand_driver = {
.driver = {
.name = “pxa3xx-nand”,
},
.probe = pxa3xx_nand_probe,
.remove = pxa3xx_nand_remove,
#ifdef CONFIG_PM
.suspend = pxa3xx_nand_suspend,
.resume = pxa3xx_nand_resume,
#endif
};
pxa3xx_nand_probe
==> add_mtd_partitions(mtd, , pdata->parts, pdata->nr_parts);
===> slave->mtd.flags = master->flags & ~parts[i].mask_flags; // 取反mask_flags做掩码操作
其中pdata->parts对应struct mtd_partition结构体
drivers/mtd/mtdblock.c
// 读写mtd的fops
static struct mtd_blktrans_ops mtdblock_tr = {
.name = “mtdblock”,
.major = 31,
.part_bits = 0,
.blksize = 512,
.open = mtdblock_open,
.flush = mtdblock_flush,
.release = mtdblock_release,
.readsect = mtdblock_readsect,
.writesect = mtdblock_writesect,
.add_mtd = mtdblock_add_mtd,
.remove_dev = mtdblock_remove_dev,
.owner = THIS_MODULE,
};
struct mtd_partition {
char *name; /* identifier string */
u_int32_t size; /* partition size */
u_int32_t offset; /* offset within the master MTD space */
u_int32_t mask_flags; /* master MTD flags to mask out for this partition */
struct nand_ecclayout *ecclayout; /* out of band layout for this partition (NAND only)*/
struct mtd_info **mtdp; /* pointer to store the MTD object */
};
// 如下即flash分区部分内容
static struct mtd_partition partition_info[] = {
{
name: “Bootloader”,
offset: 0,
mask_flags: MTD_WRITEABLE /* force read-only */ 去掉写权限
},{
name: “Kernel”,
size: 0x00200000,
mask_flags: MTD_WRITEABLE /* force read-only */ 去掉写权限
},{
name: “Filesystem”,
size: 0x05000000, /* only mount 48M fs */
}, {
name: “MassStorage”, 这里mask_flags为0,所以具有读写权限
size: 0x0, /* It will be set at probe function */
offset: MTDPART_OFS_APPEND /* Append after fs section */
},
……
};
0x00200000表示2M,即2097152
读mtd分区：dd if=/dev/mtdblock1 of=zImage bs=dd bs=2097152 count=1
写mtd分区：dd if=/gliethttp/zImage of=/dev/mtdblock1