Commit 388161ca authored by Michael Walle's avatar Michael Walle Committed by Vignesh Raghavendra
Browse files

mtd: spi-nor: otp: return -EROFS if region is read-only 



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: 069089ac ("mtd: spi-nor: add OTP support")
Signed-off-by: default avatarMichael Walle <michael@walle.cc>
Signed-off-by: default avatarVignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: default avatarPratyush Yadav <p.yadav@ti.com>
Reviewed-by: default avatarTudor Ambarus <tudor.ambarus@microchip.com>
parent d5b813e4

drivers/mtd/spi-nor/otp.c

+38 −3
Original line number Diff line number Diff line
@@ -249,6 +249,29 @@ static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len, 
	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)
@@ -264,14 +287,26 @@ 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