Linux塊裝置方式的nvram驅動例項

一般可以通過字元裝置驅動的方式訪問nvram，在這裡，通過塊裝置驅動方式去驅動nvram，以了解和熟悉塊裝置驅動編寫。

測試系統：fedora7

nvram總可接大小：8k x 64頁 x 8片 = 4 m 位元組

測試硬體：intel板卡

#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define nvram_name "board_nvram"
#define nvram_size 0x80000
#define nvram_blocksize 512
struct nvram_dev_t;
struct nvram_dev_t nvram_dev;
static
int hardsect=nvram_blocksize;
static
int major=224;
static
int minor = 0; 
static
int iobaadr = 0x300; //板卡io空間基位址
static
unsigned
long membaadr=0xdc000; //記憶體空間基位址
static
unsigned
long mem_len=8192; //頁對映長度bytes
char* preg;
void selectpage(unsigned page)
static
void nvram_transfer(struct nvram_dev_t *dev, unsigned
long sector, unsigned
long nsect, char *buffer, int write)
offset=(sector * hardsect) & (mem_len-1); 
index= (sector* hardsect)>>13; 
rdptr = preg+ offset; 
r_size=nbytes; 
if(r_size>(mem_len-offset))else 
time=1;
if (write) //write
while(time) 
else
//read
while(time)
}static
int nvram_xfer_bio(struct nvram_dev_t *dev, struct bio *bio)
return
0; /* always "succeed" */
}static
int nvram_make_request(request_queue_t *queue,struct bio *bio)
int nvram_open(struct inode *inode, struct file *filp) 
int nvram_release(struct inode *inode, struct file *filp) 
int nvram_ioctl (struct inode *inode, struct file *filp,
unsigned
int cmd, unsigned
long arg)
return -enotty; /* unknown command */
}struct block_device_operations nvram_bdops =; 
static
void __exit nvram_exit(void)
if (nvram_dev.queue) 
unregister_blkdev(major, "nvram");
unregister_chrdev_region(mkdev(major,minor), 1); 
release_region(iobaadr, 13);
release_mem_region(membaadr, mem_len);
iounmap(preg);
printk("board nvram driver unloaded\n");
}static
int nvram_init(void)
nvram_dev.disk= alloc_disk(1);
if (!nvram_dev.disk)
nvram_dev.queue= blk_alloc_queue(gfp_kernel);
if (!nvram_dev.queue) 
if (register_blkdev(major, "nvram")) 
if (null == request_region(iobaadr, 13, nvram_name))
if (null == request_mem_region(membaadr, mem_len, nvram_name)) 
preg= ioremap(membaadr,mem_len);
disk= nvram_dev.disk;
blk_queue_make_request(nvram_dev.queue,&nvram_make_request);
blk_queue_hardsect_size(nvram_dev.queue, hardsect);
/* rd_size is given in kb */
disk->major = major;
disk->first_minor = 0;
disk->fops = &nvram_bdops;
disk->queue = nvram_dev.queue;
sprintf(disk->disk_name, "nvram%d", 0);
set_capacity(disk, 1024);
add_disk(disk);
outb_p(0x55,iobaadr+9); //nvram 片選使能
printk("nvram is initialized\n");
return
0; out:
unregister_chrdev_region(devno, 1); 
put_disk(nvram_dev.disk);
blk_cleanup_queue(nvram_dev.queue);
return err;
}module_init(nvram_init);
module_exit(nvram_exit);
module_license("dual bsd/gpl");

insmod board_nvram.ko

mkfs.ext2 /dev/nvram0

mount /dev/nvram0 /mnt

linux的塊裝置層

ll rw block 是塊裝置驅動層，向上提供按block讀寫塊裝置到某個記憶體位址的 是以page為目標單位 方法 bread 是塊裝置緩衝層，磁碟上的block用頁快取 先從這個快取裡找，找不到再呼叫ll rw block 讀進來 各個檔案系統，要向vfs層提供read inode 這樣的介面...

Linux塊裝置驅動

塊裝置提供塊裝置提供裝置的訪問，裝置的訪問，可以隨機的以固定大小的塊傳輸資料，例如我們最為常見的磁碟裝置，當然塊裝置和字元裝置有較大差別，塊裝置有自己的驅動介面。簡單來說，核心決定乙個塊是固定的4096 位元組，當然該值可以隨著依賴檔案系統的變化而改變。塊裝置驅動採用register blkdev向...

Linux塊裝置驅動之記憶體模擬塊裝置

用記憶體代替塊裝置的總結,相對來簡單得多，對記憶體操作想必大家都很熟悉，直接分配一塊記憶體就可以直接讀寫操作了 參考 drivers block xd.c drivers block z2ram.c define ramblock size 1024 1024 乙個扇區是512位元組 static ...