1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Direct MTD block device access
5  * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
6  * Copyright © 2000-2003 Nicolas Pitre <nico@fluxnic.net>
18 #include <linux/mtd/mtd.h>
19 #include <linux/mtd/blktrans.h>
38  * buffer cache can handle, we must implement read-modify-write on flash
39  * sectors for each block write requests.  To avoid over-erasing flash sectors
44 static int erase_write (struct mtd_info *mtd, unsigned long pos,  in erase_write()  argument
57 	ret = mtd_erase(mtd, &erase);  in erase_write()
61 			pos, len, mtd->name);  in erase_write()
69 	ret = mtd_write(mtd, pos, len, &retlen, buf);  in erase_write()
73 		return -EIO;  in erase_write()
80 	struct mtd_info *mtd = mtdblk->mbd.mtd;  in write_cached_data()  local
83 	if (mtdblk->cache_state != STATE_DIRTY)  in write_cached_data()
87 			"at 0x%lx, size 0x%x\n", mtd->name,  in write_cached_data()
88 			mtdblk->cache_offset, mtdblk->cache_size);  in write_cached_data()
90 	ret = erase_write (mtd, mtdblk->cache_offset,  in write_cached_data()
91 			   mtdblk->cache_size, mtdblk->cache_data);  in write_cached_data()
104 	if (ret == 0 || ret == -EIO)  in write_cached_data()
105 		mtdblk->cache_state = STATE_EMPTY;  in write_cached_data()
113 	struct mtd_info *mtd = mtdblk->mbd.mtd;  in do_cached_write()  local
114 	unsigned int sect_size = mtdblk->cache_size;  in do_cached_write()
119 		mtd->name, pos, len);  in do_cached_write()
122 		return mtd_write(mtd, pos, len, &retlen, buf);  in do_cached_write()
126 		unsigned int offset = pos - sect_start;  in do_cached_write()
127 		unsigned int size = sect_size - offset;  in do_cached_write()
137 			ret = erase_write (mtd, pos, size, buf);  in do_cached_write()
143 			if (mtdblk->cache_state == STATE_DIRTY &&  in do_cached_write()
144 			    mtdblk->cache_offset != sect_start) {  in do_cached_write()
150 			if (mtdblk->cache_state == STATE_EMPTY ||  in do_cached_write()
151 			    mtdblk->cache_offset != sect_start) {  in do_cached_write()
153 				mtdblk->cache_state = STATE_EMPTY;  in do_cached_write()
154 				ret = mtd_read(mtd, sect_start, sect_size,  in do_cached_write()
155 					       &retlen, mtdblk->cache_data);  in do_cached_write()
159 					return -EIO;  in do_cached_write()
161 				mtdblk->cache_offset = sect_start;  in do_cached_write()
162 				mtdblk->cache_size = sect_size;  in do_cached_write()
163 				mtdblk->cache_state = STATE_CLEAN;  in do_cached_write()
167 			memcpy (mtdblk->cache_data + offset, buf, size);  in do_cached_write()
168 			mtdblk->cache_state = STATE_DIRTY;  in do_cached_write()
173 		len -= size;  in do_cached_write()
183 	struct mtd_info *mtd = mtdblk->mbd.mtd;  in do_cached_read()  local
184 	unsigned int sect_size = mtdblk->cache_size;  in do_cached_read()
189 			mtd->name, pos, len);  in do_cached_read()
192 		return mtd_read(mtd, pos, len, &retlen, buf);  in do_cached_read()
196 		unsigned int offset = pos - sect_start;  in do_cached_read()
197 		unsigned int size = sect_size - offset;  in do_cached_read()
207 		if (mtdblk->cache_state != STATE_EMPTY &&  in do_cached_read()
208 		    mtdblk->cache_offset == sect_start) {  in do_cached_read()
209 			memcpy (buf, mtdblk->cache_data + offset, size);  in do_cached_read()
211 			ret = mtd_read(mtd, pos, size, &retlen, buf);  in do_cached_read()
215 				return -EIO;  in do_cached_read()
220 		len -= size;  in do_cached_read()
237 	if (unlikely(!mtdblk->cache_data && mtdblk->cache_size)) {  in mtdblock_writesect()
238 		mtdblk->cache_data = vmalloc(mtdblk->mbd.mtd->erasesize);  in mtdblock_writesect()
239 		if (!mtdblk->cache_data)  in mtdblock_writesect()
240 			return -EINTR;  in mtdblock_writesect()
241 		/* -EINTR is not really correct, but it is the best match  in mtdblock_writesect()
243 		 * return -EAGAIN sometimes, but why bother?  in mtdblock_writesect()
255 	if (mtdblk->count) {  in mtdblock_open()
256 		mtdblk->count++;  in mtdblock_open()
260 	if (mtd_type_is_nand(mbd->mtd))  in mtdblock_open()
261 		pr_warn("%s: MTD device '%s' is NAND, please consider using UBI block devices instead.\n",  in mtdblock_open()
262 			mbd->tr->name, mbd->mtd->name);  in mtdblock_open()
265 	mtdblk->count = 1;  in mtdblock_open()
266 	mutex_init(&mtdblk->cache_mutex);  in mtdblock_open()
267 	mtdblk->cache_state = STATE_EMPTY;  in mtdblock_open()
268 	if (!(mbd->mtd->flags & MTD_NO_ERASE) && mbd->mtd->erasesize) {  in mtdblock_open()
269 		mtdblk->cache_size = mbd->mtd->erasesize;  in mtdblock_open()
270 		mtdblk->cache_data = NULL;  in mtdblock_open()
284 	mutex_lock(&mtdblk->cache_mutex);  in mtdblock_release()
286 	mutex_unlock(&mtdblk->cache_mutex);  in mtdblock_release()
288 	if (!--mtdblk->count) {  in mtdblock_release()
293 		if (mbd->file_mode & FMODE_WRITE)  in mtdblock_release()
294 			mtd_sync(mbd->mtd);  in mtdblock_release()
295 		vfree(mtdblk->cache_data);  in mtdblock_release()
306 	mutex_lock(&mtdblk->cache_mutex);  in mtdblock_flush()
308 	mutex_unlock(&mtdblk->cache_mutex);  in mtdblock_flush()
309 	mtd_sync(dev->mtd);  in mtdblock_flush()
313 static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)  in mtdblock_add_mtd()  argument
320 	dev->mbd.mtd = mtd;  in mtdblock_add_mtd()
321 	dev->mbd.devnum = mtd->index;  in mtdblock_add_mtd()
323 	dev->mbd.size = mtd->size >> 9;  in mtdblock_add_mtd()
324 	dev->mbd.tr = tr;  in mtdblock_add_mtd()
326 	if (!(mtd->flags & MTD_WRITEABLE))  in mtdblock_add_mtd()
327 		dev->mbd.readonly = 1;  in mtdblock_add_mtd()
329 	if (add_mtd_blktrans_dev(&dev->mbd))  in mtdblock_add_mtd()
339 	.name		= "mtdblock",
357 MODULE_DESCRIPTION("Caching read/erase/writeback block device emulation access to MTD devices");