/**
* nor_erase_prepare - prepare a NOR flash PEB for erasure.
* @ubi: UBI device description object
* @pnum: physical eraseblock number to prepare
*
* NOR flash, or at least some of them, have peculiar embedded PEB erasure
* algorithm: the PEB is first filled with zeroes, then it is erased. And
* filling with zeroes starts from the end of the PEB. This was observed with
* Spansion S29GL512N NOR flash.
*
* This means that in case of a power cut we may end up with intact data at the
* beginning of the PEB, and all zeroes at the end of PEB. In other words, the
* EC and VID headers are OK, but a large chunk of data at the end of PEB is
* zeroed. This makes UBI mistakenly treat this PEB as used and associate it
* with an LEB, which leads to subsequent failures (e.g., UBIFS fails).
*
* This function is called before erasing NOR PEBs and it zeroes out EC and VID
* magic numbers in order to invalidate them and prevent the failures. Returns
* zero in case of success and a negative error code in case of failure.
*/
static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
{
int err;
size_t written;
loff_t addr;
uint32_t data = 0;
struct ubi_ec_hdr ec_hdr;
struct ubi_vid_io_buf vidb;
/*
* Note, we cannot generally define VID header buffers on stack,
* because of the way we deal with these buffers (see the header
* comment in this file). But we know this is a NOR-specific piece of
* code, so we can do this. But yes, this is error-prone and we should
* (pre-)allocate VID header buffer instead.
*/
struct ubi_vid_hdr vid_hdr;
/*
* If VID or EC is valid, we have to corrupt them before erasing.
* It is important to first invalidate the EC header, and then the VID
* header. Otherwise a power cut may lead to valid EC header and
* invalid VID header, in which case UBI will treat this PEB as
* corrupted and will try to preserve it, and print scary warnings.
*/
addr = (loff_t)pnum * ubi->peb_size;
err = ubi_io_read_ec_hdr(ubi, pnum, &ec_hdr, 0);
if (err != UBI_IO_BAD_HDR_EBADMSG && err != UBI_IO_BAD_HDR &&
err != UBI_IO_FF){
err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
if(err)
goto error;
}
ubi_init_vid_buf(ubi, &vidb, &vid_hdr);
ubi_assert(&vid_hdr == ubi_get_vid_hdr(&vidb));
err = ubi_io_read_vid_hdr(ubi, pnum, &vidb, 0);
if (err != UBI_IO_BAD_HDR_EBADMSG && err != UBI_IO_BAD_HDR &&
err != UBI_IO_FF){
addr += ubi->vid_hdr_aloffset;
err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
if (err)
goto error;
}
return 0;
error:
/*
* The PEB contains a valid VID or EC header, but we cannot invalidate
* it. Supposedly the flash media or the driver is screwed up, so
* return an error.
*/
ubi_err(ubi, "cannot invalidate PEB %d, write returned %d", pnum, err);
ubi_dump_flash(ubi, pnum, 0, ubi->peb_size);
return -EIO;
}
/**
* ubi_io_write - write data to a physical eraseblock.
* @ubi: UBI device description object
* @buf: buffer with the data to write
* @pnum: physical eraseblock number to write to
* @offset: offset within the physical eraseblock where to write
* @len: how many bytes to write
*
* This function writes @len bytes of data from buffer @buf to offset @offset
* of physical eraseblock @pnum. If all the data were successfully written,
* zero is returned. If an error occurred, this function returns a negative
* error code. If %-EIO is returned, the physical eraseblock most probably went
* bad.
*
* Note, in case of an error, it is possible that something was still written
* to the flash media, but may be some garbage.
*/
int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
int len)
{
int err;
size_t written;
loff_t addr;
dbg_io("write %d bytes to PEB %d:%d", len, pnum, offset);
ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
ubi_assert(offset % ubi->hdrs_min_io_size == 0);
ubi_assert(len > 0 && len % ubi->hdrs_min_io_size == 0);
if (ubi->ro_mode) {
ubi_err(ubi, "read-only mode");
return -EROFS;
}
err = self_check_not_bad(ubi, pnum);
if (err)
return err;
/* The area we are writing to has to contain all 0xFF bytes */
err = ubi_self_check_all_ff(ubi, pnum, offset, len);
if (err)
return err;
if (offset >= ubi->leb_start) {
/*
* We write to the data area of the physical eraseblock. Make
* sure it has valid EC and VID headers.
*/
err = self_check_peb_ec_hdr(ubi, pnum);
if (err)
return err;
err = self_check_peb_vid_hdr(ubi, pnum);
if (err)
return err;
}
if (ubi_dbg_is_write_failure(ubi)) {
ubi_err(ubi, "cannot write %d bytes to PEB %d:%d (emulated)",
len, pnum, offset);
dump_stack();
return -EIO;
}
addr = (loff_t)pnum * ubi->peb_size + offset;
err = mtd_write(ubi->mtd, addr, len, &written, buf);
if (err) {
ubi_err(ubi, "error %d while writing %d bytes to PEB %d:%d, written %zd bytes",
err, len, pnum, offset, written);
dump_stack();
ubi_dump_flash(ubi, pnum, offset, len);
} else
ubi_assert(written == len);
if (!err) {
err = self_check_write(ubi, buf, pnum, offset, len);
if (err)
return err;
/*
* Since we always write sequentially, the rest of the PEB has
* to contain only 0xFF bytes.
*/
offset += len;
len = ubi->peb_size - offset;
if (len)
err = ubi_self_check_all_ff(ubi, pnum, offset, len);
}
return err;
}
/**
* nor_erase_prepare - prepare a NOR flash PEB for erasure.
* @ubi: UBI device description object
* @pnum: physical eraseblock number to prepare
*
* NOR flash, or at least some of them, have peculiar embedded PEB erasure
* algorithm: the PEB is first filled with zeroes, then it is erased. And
* filling with zeroes starts from the end of the PEB. This was observed with
* Spansion S29GL512N NOR flash.
*
* This means that in case of a power cut we may end up with intact data at the
* beginning of the PEB, and all zeroes at the end of PEB. In other words, the
* EC and VID headers are OK, but a large chunk of data at the end of PEB is
* zeroed. This makes UBI mistakenly treat this PEB as used and associate it
* with an LEB, which leads to subsequent failures (e.g., UBIFS fails).
*
* This function is called before erasing NOR PEBs and it zeroes out EC and VID
* magic numbers in order to invalidate them and prevent the failures. Returns
* zero in case of success and a negative error code in case of failure.
*/
static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
{
int err, err1;
size_t written;
loff_t addr;
uint32_t data = 0;
/*
* Note, we cannot generally define VID header buffers on stack,
* because of the way we deal with these buffers (see the header
* comment in this file). But we know this is a NOR-specific piece of
* code, so we can do this. But yes, this is error-prone and we should
* (pre-)allocate VID header buffer instead.
*/
struct ubi_vid_hdr vid_hdr;
/*
* It is important to first invalidate the EC header, and then the VID
* header. Otherwise a power cut may lead to valid EC header and
* invalid VID header, in which case UBI will treat this PEB as
* corrupted and will try to preserve it, and print scary warnings.
*/
addr = (loff_t)pnum * ubi->peb_size;
err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
if (!err) {
addr += ubi->vid_hdr_aloffset;
err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
if (!err)
return 0;
}
/*
* We failed to write to the media. This was observed with Spansion
* S29GL512N NOR flash. Most probably the previously eraseblock erasure
* was interrupted at a very inappropriate moment, so it became
* unwritable. In this case we probably anyway have garbage in this
* PEB.
*/
err1 = ubi_io_read_vid_hdr(ubi, pnum, &vid_hdr, 0);
if (err1 == UBI_IO_BAD_HDR_EBADMSG || err1 == UBI_IO_BAD_HDR ||
err1 == UBI_IO_FF) {
struct ubi_ec_hdr ec_hdr;
err1 = ubi_io_read_ec_hdr(ubi, pnum, &ec_hdr, 0);
if (err1 == UBI_IO_BAD_HDR_EBADMSG || err1 == UBI_IO_BAD_HDR ||
err1 == UBI_IO_FF)
/*
* Both VID and EC headers are corrupted, so we can
* safely erase this PEB and not afraid that it will be
* treated as a valid PEB in case of an unclean reboot.
*/
return 0;
}
/*
* The PEB contains a valid VID header, but we cannot invalidate it.
* Supposedly the flash media or the driver is screwed up, so return an
* error.
*/
ubi_err("cannot invalidate PEB %d, write returned %d read returned %d",
pnum, err, err1);
ubi_dump_flash(ubi, pnum, 0, ubi->peb_size);
return -EIO;
}
