/* * block2mtd.c - create an mtd from a block device * * Copyright (C) 2001,2002 Simon Evans * Copyright (C) 2004-2006 Joern Engel * * Licence: GPL */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt /* * When the first attempt at device initialization fails, we may need to * wait a little bit and retry. This timeout, by default 3 seconds, gives * device time to start up. Required on BCM2708 and a few other chipsets. */ #define MTD_DEFAULT_TIMEOUT 3 #include #include #include #include #include #include #include #include #include #include #include #include #include /* Info for the block device */ struct block2mtd_dev { struct list_head list; struct block_device *blkdev; struct mtd_info mtd; struct mutex write_mutex; }; /* Static info about the MTD, used in cleanup_module */ static LIST_HEAD(blkmtd_device_list); static struct page *page_read(struct address_space *mapping, int index) { return read_mapping_page(mapping, index, NULL); } /* erase a specified part of the device */ static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len) { struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; struct page *page; int index = to >> PAGE_SHIFT; // page index int pages = len >> PAGE_SHIFT; u_long *p; u_long *max; while (pages) { page = page_read(mapping, index); if (IS_ERR(page)) return PTR_ERR(page); max = page_address(page) + PAGE_SIZE; for (p=page_address(page); ppriv; size_t from = instr->addr; size_t len = instr->len; int err; instr->state = MTD_ERASING; mutex_lock(&dev->write_mutex); err = _block2mtd_erase(dev, from, len); mutex_unlock(&dev->write_mutex); if (err) { pr_err("erase failed err = %d\n", err); instr->state = MTD_ERASE_FAILED; } else instr->state = MTD_ERASE_DONE; mtd_erase_callback(instr); return err; } static int block2mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf) { struct block2mtd_dev *dev = mtd->priv; struct page *page; int index = from >> PAGE_SHIFT; int offset = from & (PAGE_SIZE-1); int cpylen; while (len) { if ((offset + len) > PAGE_SIZE) cpylen = PAGE_SIZE - offset; // multiple pages else cpylen = len; // this page len = len - cpylen; page = page_read(dev->blkdev->bd_inode->i_mapping, index); if (IS_ERR(page)) return PTR_ERR(page); memcpy(buf, page_address(page) + offset, cpylen); page_cache_release(page); if (retlen) *retlen += cpylen; buf += cpylen; offset = 0; index++; } return 0; } /* write data to the underlying device */ static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf, loff_t to, size_t len, size_t *retlen) { struct page *page; struct address_space *mapping = dev->blkdev->bd_inode->i_mapping; int index = to >> PAGE_SHIFT; // page index int offset = to & ~PAGE_MASK; // page offset int cpylen; while (len) { if ((offset+len) > PAGE_SIZE) cpylen = PAGE_SIZE - offset; // multiple pages else cpylen = len; // this page len = len - cpylen; page = page_read(mapping, index); if (IS_ERR(page)) return PTR_ERR(page); if (memcmp(page_address(page)+offset, buf, cpylen)) { lock_page(page); memcpy(page_address(page) + offset, buf, cpylen); set_page_dirty(page); unlock_page(page); balance_dirty_pages_ratelimited(mapping); } page_cache_release(page); if (retlen) *retlen += cpylen; buf += cpylen; offset = 0; index++; } return 0; } static int block2mtd_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf) { struct block2mtd_dev *dev = mtd->priv; int err; mutex_lock(&dev->write_mutex); err = _block2mtd_write(dev, buf, to, len, retlen); mutex_unlock(&dev->write_mutex); if (err > 0) err = 0; return err; } /*