[PATCH 06/58] mtd: rawnand: macronix: serialize OTP access with NAND operations

[James Hilliard]

The Macronix OTP callbacks select a target and issue feature and page
commands without taking the chip or controller locks. A retained OTP
handle can therefore issue commands after controller disconnection, and
normal NAND I/O can also interfere with the temporary OTP mode.

Take the common NAND operation locks around the entire OTP transaction,
including restoring normal mode. This also rejects operations on a
disconnected chip and waits for suspended chips using the normal NAND
rules.

Fixes: e87161321a40 ("mtd: rawnand: macronix: OTP access for MX30LFxG18AC")
Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
---
 drivers/mtd/nand/raw/internals.h     | 2 ++
 drivers/mtd/nand/raw/nand_base.c     | 4 ++--
 drivers/mtd/nand/raw/nand_macronix.c | 4 ++++
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/internals.h b/drivers/mtd/nand/raw/internals.h
index b8b29341b88c..dcd9536da449 100644
--- a/drivers/mtd/nand/raw/internals.h
+++ b/drivers/mtd/nand/raw/internals.h
@@ -81,6 +81,8 @@ extern const struct nand_manufacturer_ops toshiba_nand_manuf_ops;
 extern const struct mtd_pairing_scheme dist3_pairing_scheme;
 
 /* Core functions */
+int nand_get_device(struct nand_chip *chip);
+void nand_release_device(struct nand_chip *chip);
 const struct nand_manufacturer_desc *nand_get_manufacturer_desc(u8 id);
 int nand_bbm_get_next_page(struct nand_chip *chip, int page);
 int nand_markbad_bbm(struct nand_chip *chip, loff_t ofs);
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 8f7d2571e8d9..2667faf02a91 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -207,7 +207,7 @@ EXPORT_SYMBOL_GPL(nand_deselect_target);
  *
  * Release chip lock and wake up anyone waiting on the device.
  */
-static void nand_release_device(struct nand_chip *chip)
+void nand_release_device(struct nand_chip *chip)
 {
 	/* Release the controller and the chip */
 	mutex_unlock(&chip->controller->lock);
@@ -336,7 +336,7 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs)
  *
  * Lock the device and its controller for exclusive access
  */
-static int nand_get_device(struct nand_chip *chip)
+int nand_get_device(struct nand_chip *chip)
 {
 	/* Wait until the device is resumed. */
 	while (1) {
diff --git a/drivers/mtd/nand/raw/nand_macronix.c b/drivers/mtd/nand/raw/nand_macronix.c
index 03237310852c..1ffe2fc4943e 100644
--- a/drivers/mtd/nand/raw/nand_macronix.c
+++ b/drivers/mtd/nand/raw/nand_macronix.c
@@ -380,6 +380,9 @@ static int __macronix_30lfxg18ac_rw_otp(struct mtd_info *mtd,
 	int ret;
 
 	nand = mtd_to_nand(mtd);
+	ret = nand_get_device(nand);
+	if (ret)
+		return ret;
 	nand_select_target(nand, 0);
 
 	ret = macronix_30lfxg18ac_otp_enable(nand);
@@ -426,6 +429,7 @@ static int __macronix_30lfxg18ac_rw_otp(struct mtd_info *mtd,
 			write ? "write" : "read");
 
 	nand_deselect_target(nand);
+	nand_release_device(nand);
 
 	return ret;
 }

-- 
2.53.0