/* * Direct MTD block device access * * $Id: mtdblock.c,v 1.47 2001/10/02 15:05:11 dwmw2 Exp $ * * 02-nov-2000 Nicolas Pitre Added read-modify-write with cache */ #include #include #include #include #include #include #include #define MAJOR_NR MTD_BLOCK_MAJOR #define DEVICE_NAME "mtdblock" #define DEVICE_REQUEST mtdblock_request #define DEVICE_NR(device) (device) #define DEVICE_ON(device) #define DEVICE_OFF(device) #define DEVICE_NO_RANDOM #include /* for old kernels... */ #ifndef QUEUE_EMPTY #define QUEUE_EMPTY (!CURRENT) #endif #if LINUX_VERSION_CODE < 0x20300 #define QUEUE_PLUGGED (blk_dev[MAJOR_NR].plug_tq.sync) #else #define QUEUE_PLUGGED (blk_dev[MAJOR_NR].request_queue.plugged) #endif #ifdef CONFIG_DEVFS_FS #include static void mtd_notify_add(struct mtd_info* mtd); static void mtd_notify_remove(struct mtd_info* mtd); static struct mtd_notifier notifier = { mtd_notify_add, mtd_notify_remove, NULL }; static devfs_handle_t devfs_dir_handle = NULL; static devfs_handle_t devfs_rw_handle[MAX_MTD_DEVICES]; #endif static struct mtdblk_dev { struct mtd_info *mtd; /* Locked */ int count; struct semaphore cache_sem; unsigned char *cache_data; unsigned long cache_offset; unsigned int cache_size; enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state; } *mtdblks[MAX_MTD_DEVICES]; static spinlock_t mtdblks_lock; static int mtd_sizes[MAX_MTD_DEVICES]; static int mtd_blksizes[MAX_MTD_DEVICES]; /* * Cache stuff... * * Since typical flash erasable sectors are much larger than what Linux's * buffer cache can handle, we must implement read-modify-write on flash * sectors for each block write requests. To avoid over-erasing flash sectors * and to speed things up, we locally cache a whole flash sector while it is * being written to until a different sector is required. */ static void erase_callback(struct erase_info *done) { wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv; wake_up(wait_q); } static int erase_write (struct mtd_info *mtd, unsigned long pos, int len, const char *buf) { struct erase_info erase; DECLARE_WAITQUEUE(wait, current); wait_queue_head_t wait_q; size_t retlen; int ret; /* * First, let's erase the flash block. */ init_waitqueue_head(&wait_q); erase.mtd = mtd; erase.callback = erase_callback; erase.addr = pos; erase.len = len; erase.priv = (u_long)&wait_q; set_current_state(TASK_INTERRUPTIBLE); add_wait_queue(&wait_q, &wait); ret = MTD_ERASE(mtd, &erase); if (ret) { set_current_state(TASK_RUNNING); remove_wait_queue(&wait_q, &wait); printk (KERN_WARNING "mtdblock: erase of region [0x%lx, 0x%x] " "on \"%s\" failed\n", pos, len, mtd->name); return ret; } schedule(); /* Wait for erase to finish. */ remove_wait_queue(&wait_q, &wait); /* * Next, writhe data to flash. */ ret = MTD_WRITE (mtd, pos, len, &retlen, buf); if (ret) return ret; if (retlen != len) return -EIO; return 0; } static int write_cached_data (struct mtdblk_dev *mtdblk) { struct mtd_info *mtd = mtdblk->mtd; int ret; if (mtdblk->cache_state != STATE_DIRTY) return 0; DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: writing cached data for \"%s\" " "at 0x%lx, size 0x%x\n", mtd->name, mtdblk->cache_offset, mtdblk->cache_size); ret = erase_write (mtd, mtdblk->cache_offset, mtdblk->cache_size, mtdblk->cache_data); if (ret) return ret; /* * Here we could argably set the cache state to STATE_CLEAN. * However this could lead to inconsistency since we will not * be notified if this content is altered on the flash by other * means. Let's declare it empty and leave buffering tasks to * the buffer cache instead. */ mtdblk->cache_state = STATE_EMPTY; return 0; } static int do_cached_write (struct mtdblk_dev *mtdblk, unsigned long pos, int len, const char *buf) { struct mtd_info *mtd = mtdblk->mtd; unsigned int sect_size = mtdblk->cache_size; size_t retlen; int ret; DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: write on \"%s\" at 0x%lx, size 0x%x\n", mtd->name, pos, len); if (!sect_size) return MTD_WRITE (mtd, pos, len, &retlen, buf); while (len > 0) { unsigned long sect_start = (pos/sect_size)*sect_size; unsigned int offset = pos - sect_start; unsigned int size = sect_size - offset; if( size > len ) size = len; if (size == sect_size) { /* * We are covering a whole sector. Thus there is no * need to bother with the cache while it may still be * useful for other partial writes. */ ret = erase_write (mtd, pos, size, buf); if (ret) return ret; } else { /* Partial sector: need to use the cache */ if (mtdblk->cache_state == STATE_DIRTY && mtdblk->cache_offset != sect_start) { ret = write_cached_data(mtdblk); if (ret) return ret; } if (mtdblk->cache_state == STATE_EMPTY || mtdblk->cache_offset != sect_start) { /* fill the cache with the current sector */ mtdblk->cache_state = STATE_EMPTY; ret = MTD_READ(mtd, sect_start, sect_size, &retlen, mtdblk->cache_data); if (ret) return ret; if (retlen != sect_size) return -EIO; mtdblk->cache_offset = sect_start; mtdblk->cache_size = sect_size; mtdblk->cache_state = STATE_CLEAN; } /* write data to our local cache */ memcpy (mtdblk->cache_data + offset, buf, size); mtdblk->cache_state = STATE_DIRTY; } buf += size; pos += size; len -= size; } return 0; } static int do_cached_read (struct mtdblk_dev *mtdblk, unsigned long pos, int len, char *buf) { struct mtd_info *mtd = mtdblk->mtd; unsigned int sect_size = mtdblk->cache_size; size_t retlen; int ret; DEBUG(MTD_DEBUG_LEVEL2, "mtdblock: read on \"%s\" at 0x%lx, size 0x%x\n", mtd->name, pos, len); if (!sect_size) return MTD_READ (mtd, pos, len, &retlen, buf); while (len > 0) { unsigned long sect_start = (pos/sect_size)*sect_size; unsigned int offset = pos - sect_start; unsigned int size = sect_size - offset; if (size > len) size = len; /* * Check if the requested data is already cached * Read the requested amount of data from our internal cache if it * contains what we want, otherwise we read the data directly * from flash. */ if (mtdblk->cache_state != STATE_EMPTY && mtdblk->cache_offset == sect_start) { memcpy (buf, mtdblk->cache_data + offset, size); } else { ret = MTD_READ (mtd, pos, size, &retlen, buf); if (ret) return ret; if (retlen != size) return -EIO; } buf += size; pos += size; len -= size; } return 0; } static int mtdblock_open(struct inode *inode, struct file *file) { struct mtdblk_dev *mtdblk; struct mtd_info *mtd; int dev; DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n"); if (!inode) return -EINVAL; dev = MINOR(inode->i_rdev); if (dev >= MAX_MTD_DEVICES) return -EINVAL; mtd = get_mtd_device(NULL, dev); if (!mtd) return -ENODEV; if (MTD_ABSENT == mtd->type) { put_mtd_device(mtd); return -ENODEV; } spin_lock(&mtdblks_lock); /* If it's already open, no need to piss about. */ if (mtdblks[dev]) { mtdblks[dev]->count++; spin_unlock(&mtdblks_lock); return 0; } /* OK, it's not open. Try to find it */ /* First we have to drop the lock, because we have to to things which might sleep. */ spin_unlock(&mtdblks_lock); mtdblk = kmalloc(sizeof(struct mtdblk_dev), GFP_KERNEL); if (!mtdblk) { put_mtd_device(mtd); return -ENOMEM; } memset(mtdblk, 0, sizeof(*mtdblk)); mtdblk->count = 1; mtdblk->mtd = mtd; init_MUTEX (&mtdblk->cache_sem); mtdblk->cache_state = STATE_EMPTY; if ((mtdblk->mtd->flags & MTD_CAP_RAM) != MTD_CAP_RAM && mtdblk->mtd->erasesize) { mtdblk->cache_size = mtdblk->mtd->erasesize; mtdblk->cache_data = vmalloc(mtdblk->mtd->erasesize); if (!mtdblk->cache_data) { put_mtd_device(mtdblk->mtd); kfree(mtdblk); return -ENOMEM; } } /* OK, we've created a new one. Add it to the list. */ spin_lock(&mtdblks_lock); if (mtdblks[dev]) { /* Another CPU made one at the same time as us. */ mtdblks[dev]->count++; spin_unlock(&mtdblks_lock); put_mtd_device(mtdblk->mtd); vfree(mtdblk->cache_data); kfree(mtdblk); return 0; } mtdblks[dev] = mtdblk; mtd_sizes[dev] = mtdblk->mtd->size/1024; if (mtdblk->mtd->erasesize) mtd_blksizes[dev] = mtdblk->mtd->erasesize; if (mtd_blksizes[dev] > PAGE_SIZE) mtd_blksizes[dev] = PAGE_SIZE; set_device_ro (inode->i_rdev, !(mtdblk->mtd->flags & MTD_WRITEABLE)); spin_unlock(&mtdblks_lock); DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); return 0; } static release_t mtdblock_release(struct inode *inode, struct file *file) { int dev; struct mtdblk_dev *mtdblk; DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n"); if (inode == NULL) release_return(-ENODEV); invalidate_device(inode->i_rdev, 1); dev = MINOR(inode->i_rdev); mtdblk = mtdblks[dev]; down(&mtdblk->cache_sem); write_cached_data(mtdblk); up(&mtdblk->cache_sem); spin_lock(&mtdblks_lock); if (!--mtdblk->count) { /* It was the last usage. Free the device */ mtdblks[dev] = NULL; spin_unlock(&mtdblks_lock); if (mtdblk->mtd->sync) mtdblk->mtd->sync(mtdblk->mtd); put_mtd_device(mtdblk->mtd); vfree(mtdblk->cache_data); kfree(mtdblk); } else { spin_unlock(&mtdblks_lock); } DEBUG(MTD_DEBUG_LEVEL1, "ok\n"); release_return(0); } /* * This is a special request_fn because it is executed in a process context * to be able to sleep independently of the caller. The io_request_lock * is held upon entry and exit. * The head of our request queue is considered active so there is no need * to dequeue requests before we are done. */ static void handle_mtdblock_request(void) { struct request *req; struct mtdblk_dev *mtdblk; unsigned int res; for (;;) { INIT_REQUEST; req = CURRENT; spin_unlock_irq(&io_request_lock); mtdblk = mtdblks[MINOR(req->rq_dev)]; res = 0; if (MINOR(req->rq_dev) >= MAX_MTD_DEVICES) panic(__FUNCTION__": minor out of bound"); if ((req->sector + req->current_nr_sectors) > (mtdblk->mtd->size >> 9)) goto end_req; // Handle the request switch (req->cmd) { int err; case READ: down(&mtdblk->cache_sem); err = do_cached_read (mtdblk, req->sector << 9, req->current_nr_sectors << 9, req->buffer); up(&mtdblk->cache_sem); if (!err) res = 1; break; case WRITE: // Read only device if ( !(mtdblk->mtd->flags & MTD_WRITEABLE) ) break; // Do the write down(&mtdblk->cache_sem); err = do_cached_write (mtdblk, req->sector << 9, req->current_nr_sectors << 9, req->buffer); up(&mtdblk->cache_sem); if (!err) res = 1; break; } end_req: spin_lock_irq(&io_request_lock); end_request(res); } } static volatile int leaving = 0; static DECLARE_MUTEX_LOCKED(thread_sem); static DECLARE_WAIT_QUEUE_HEAD(thr_wq); int mtdblock_thread(void *dummy) { struct task_struct *tsk = current; DECLARE_WAITQUEUE(wait, tsk); tsk->session = 1; tsk->pgrp = 1; /* we might get involved when memory gets low, so use PF_MEMALLOC */ tsk->flags |= PF_MEMALLOC; strcpy(tsk->comm, "mtdblockd"); tsk->tty = NULL; spin_lock_irq(&tsk->sigmask_lock); sigfillset(&tsk->blocked); recalc_sigpending(tsk); spin_unlock_irq(&tsk->sigmask_lock); exit_mm(tsk); exit_files(tsk); exit_sighand(tsk); exit_fs(tsk); while (!leaving) { add_wait_queue(&thr_wq, &wait); set_current_state(TASK_INTERRUPTIBLE); spin_lock_irq(&io_request_lock); if (QUEUE_EMPTY || QUEUE_PLUGGED) { spin_unlock_irq(&io_request_lock); schedule(); remove_wait_queue(&thr_wq, &wait); } else { remove_wait_queue(&thr_wq, &wait); set_current_state(TASK_RUNNING); handle_mtdblock_request(); spin_unlock_irq(&io_request_lock); } } up(&thread_sem); return 0; } #if LINUX_VERSION_CODE < 0x20300 #define RQFUNC_ARG void #else #define RQFUNC_ARG request_queue_t *q #endif static void mtdblock_request(RQFUNC_ARG) { /* Don't do anything, except wake the thread if necessary */ wake_up(&thr_wq); } static int mtdblock_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg) { struct mtdblk_dev *mtdblk; mtdblk = mtdblks[MINOR(inode->i_rdev)]; #ifdef PARANOIA if (!mtdblk) BUG(); #endif switch (cmd) { case BLKGETSIZE: /* Return device size */ return put_user((mtdblk->mtd->size >> 9), (unsigned long *) arg); case BLKGETSIZE64: return put_user((u64)mtdblk->mtd->size, (u64 *)arg); case BLKFLSBUF: #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,2,0) if(!capable(CAP_SYS_ADMIN)) return -EACCES; #endif fsync_dev(inode->i_rdev); invalidate_buffers(inode->i_rdev); down(&mtdblk->cache_sem); write_cached_data(mtdblk); up(&mtdblk->cache_sem); if (mtdblk->mtd->sync) mtdblk->mtd->sync(mtdblk->mtd); return 0; default: return -EINVAL; } } #if LINUX_VERSION_CODE < 0x20326 static struct file_operations mtd_fops = { open: mtdblock_open, ioctl: mtdblock_ioctl, release: mtdblock_release, read: block_read, write: block_write }; #else static struct block_device_operations mtd_fops = { owner: THIS_MODULE, open: mtdblock_open, release: mtdblock_release, ioctl: mtdblock_ioctl }; #endif #ifdef CONFIG_DEVFS_FS /* Notification that a new device has been added. Create the devfs entry for * it. */ static void mtd_notify_add(struct mtd_info* mtd) { char name[8]; if (!mtd || mtd->type == MTD_ABSENT) return; sprintf(name, "%d", mtd->index); devfs_rw_handle[mtd->index] = devfs_register(devfs_dir_handle, name, DEVFS_FL_DEFAULT, MTD_BLOCK_MAJOR, mtd->index, S_IFBLK | S_IRUGO | S_IWUGO, &mtd_fops, NULL); } static void mtd_notify_remove(struct mtd_info* mtd) { if (!mtd || mtd->type == MTD_ABSENT) return; devfs_unregister(devfs_rw_handle[mtd->index]); } #endif int __init init_mtdblock(void) { int i; spin_lock_init(&mtdblks_lock); #ifdef CONFIG_DEVFS_FS if (devfs_register_blkdev(MTD_BLOCK_MAJOR, DEVICE_NAME, &mtd_fops)) { printk(KERN_NOTICE "Can't allocate major number %d for Memory Technology Devices.\n", MTD_BLOCK_MAJOR); return -EAGAIN; } devfs_dir_handle = devfs_mk_dir(NULL, DEVICE_NAME, NULL); register_mtd_user(¬ifier); #else if (register_blkdev(MAJOR_NR,DEVICE_NAME,&mtd_fops)) { printk(KERN_NOTICE "Can't allocate major number %d for Memory Technology Devices.\n", MTD_BLOCK_MAJOR); return -EAGAIN; } #endif /* We fill it in at open() time. */ for (i=0; i< MAX_MTD_DEVICES; i++) { mtd_sizes[i] = 0; mtd_blksizes[i] = BLOCK_SIZE; } init_waitqueue_head(&thr_wq); /* Allow the block size to default to BLOCK_SIZE. */ blksize_size[MAJOR_NR] = mtd_blksizes; blk_size[MAJOR_NR] = mtd_sizes; blk_init_queue(BLK_DEFAULT_QUEUE(MAJOR_NR), &mtdblock_request); kernel_thread (mtdblock_thread, NULL, CLONE_FS|CLONE_FILES|CLONE_SIGHAND); return 0; } static void __exit cleanup_mtdblock(void) { leaving = 1; wake_up(&thr_wq); down(&thread_sem); #ifdef CONFIG_DEVFS_FS unregister_mtd_user(¬ifier); devfs_unregister(devfs_dir_handle); devfs_unregister_blkdev(MTD_BLOCK_MAJOR, DEVICE_NAME); #else unregister_blkdev(MAJOR_NR,DEVICE_NAME); #endif blk_cleanup_queue(BLK_DEFAULT_QUEUE(MAJOR_NR)); blksize_size[MAJOR_NR] = NULL; blk_size[MAJOR_NR] = NULL; } module_init(init_mtdblock); module_exit(cleanup_mtdblock); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Nicolas Pitre et al."); MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");