From: Michael Walle <michael@xxxxxxxx>
[ 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@xxxxxxxx>
Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
Reviewed-by: Pratyush Yadav <p.yadav@xxxxxx>
Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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
--
2.30.2
