From: Michael Walle michael@walle.cc
[ Upstream commit 388161ca45c911f566b71716bce5ff0119fb5522 ]
SPI NOR flashes will just ignore program commands if the OTP region is locked. Thus, a user might not notice that the intended write didn't end up in the flash. Return -EROFS to the user in this case. From what I can tell, chips/cfi_cmdset_0001.c also return this error code.
One could optimize spi_nor_mtd_otp_range_is_locked() to read the status register only once and not for every OTP region, but for that we would need some more invasive changes. Given that this is one-time-programmable memory and the normal access mode is reading, we just live with the small overhead.
By moving the code around a bit, we can just check the length before calling spi_nor_mtd_otp_range_is_locked() and avoid an underflow there if a len is 0. This way we don't need to take the lock either. We also skip the "*retlen = 0" assignment, mtdcore already takes care of that for us.
Fixes: 069089acf88b ("mtd: spi-nor: add OTP support") Signed-off-by: Michael Walle michael@walle.cc Signed-off-by: Vignesh Raghavendra vigneshr@ti.com Reviewed-by: Pratyush Yadav p.yadav@ti.com Reviewed-by: Tudor Ambarus tudor.ambarus@microchip.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mtd/spi-nor/otp.c | 41 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c index 5c51a2c9be61..d8e68120a4b1 100644 --- a/drivers/mtd/spi-nor/otp.c +++ b/drivers/mtd/spi-nor/otp.c @@ -238,6 +238,29 @@ out: return ret; }
+static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs, + size_t len) +{ + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; + unsigned int region; + int locked; + + /* + * If any of the affected OTP regions are locked the entire range is + * considered locked. + */ + for (region = spi_nor_otp_offset_to_region(nor, ofs); + region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1); + region++) { + locked = ops->is_locked(nor, region); + /* take the branch it is locked or in case of an error */ + if (locked) + return locked; + } + + return 0; +} + static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, size_t total_len, size_t *retlen, const u8 *buf, bool is_write) @@ -253,14 +276,26 @@ static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, if (ofs < 0 || ofs >= spi_nor_otp_size(nor)) return 0;
+ /* don't access beyond the end */ + total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); + + if (!total_len) + return 0; + ret = spi_nor_lock_and_prep(nor); if (ret) return ret;
- /* don't access beyond the end */ - total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); + if (is_write) { + ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len); + if (ret < 0) { + goto out; + } else if (ret) { + ret = -EROFS; + goto out; + } + }
- *retlen = 0; while (total_len) { /* * The OTP regions are mapped into a contiguous area starting