[PATCH v4 0/3] mtd: spi-nor: keep lock bits if they are non-volatile

[PATCH v4 0/3] mtd: spi-nor: keep lock bits if they are non-volatile

[Michael Walle]

I bundled this as a series, because otherwise there will be conflicts
because the "remove global protection flag" patches modify the same lines
as the main patch.

See invdividual patches for the version history.

Michael Walle (3):
  mtd: spi-nor: atmel: remove global protection flag
  mtd: spi-nor: sst: remove global protection flag
  mtd: spi-nor: keep lock bits if they are non-volatile

 drivers/mtd/spi-nor/Kconfig |  42 ++++++++++++
 drivers/mtd/spi-nor/atmel.c | 129 ++++++++++++++++++++++++++++++------
 drivers/mtd/spi-nor/core.c  |  36 +++++++---
 drivers/mtd/spi-nor/core.h  |   8 +++
 drivers/mtd/spi-nor/esmt.c  |   8 ++-
 drivers/mtd/spi-nor/intel.c |   6 +-
 drivers/mtd/spi-nor/sst.c   |  31 ++++-----
 7 files changed, 206 insertions(+), 54 deletions(-)

-- 
2.20.1


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[PATCH v4 1/3] mtd: spi-nor: atmel: remove global protection flag

[Michael Walle]

This is considered bad for the following reasons:
 (1) We only support the block protection with BPn bits for write
     protection. Not all Atmel parts support this.
 (2) Newly added flash chip will automatically inherit the "has
     locking" support and thus needs to explicitly tested. Better
     be opt-in instead of opt-out.
 (3) There are already supported flashes which doesn't support
     the locking scheme. So I assume this wasn't properly tested
     before adding that chip; which enforces my previous argument
     that locking support should be an opt-in.

Remove the global flag and add individual flags to all flashes which
supports BP locking. In particular the following flashes don't support
the BP scheme:
 - AT26F004
 - AT25SL321
 - AT45DB081D

Please note, that some flashes which are marked as SPI_NOR_HAS_LOCK just
support Global Protection, i.e. not our supported block protection
locking scheme. This is to keep backwards compatibility with the
current "unlock all at boot" mechanism. In particular the following
flashes doesn't have BP bits:
 - AT25DF041A
 - AT25DF321
 - AT25DF321A
 - AT25DF641
 - AT26DF081A
 - AT26DF161A
 - AT26DF321

Signed-off-by: Michael Walle <michael@walle.cc>
---
changes since RFC:
 - mention the flashes which just support the "Global Unprotect" in the
   commit message

 drivers/mtd/spi-nor/atmel.c | 28 +++++++++-------------------
 1 file changed, 9 insertions(+), 19 deletions(-)

diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
index 3f5f21a473a6..49d392c6c8bc 100644
--- a/drivers/mtd/spi-nor/atmel.c
+++ b/drivers/mtd/spi-nor/atmel.c
@@ -10,37 +10,27 @@
 
 static const struct flash_info atmel_parts[] = {
 	/* Atmel -- some are (confusingly) marketed as "DataFlash" */
-	{ "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K) },
-	{ "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K) },
+	{ "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK) },
 
-	{ "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K) },
-	{ "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64, SECT_4K) },
-	{ "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K) },
-	{ "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },
+	{ "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K | SPI_NOR_HAS_LOCK) },
 
 	{ "at25sl321",	INFO(0x1f4216, 0, 64 * 1024, 64,
 			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 
 	{ "at26f004",   INFO(0x1f0400, 0, 64 * 1024,  8, SECT_4K) },
-	{ "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K) },
-	{ "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K) },
-	{ "at26df321",  INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K) },
+	{ "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at26df321",  INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K | SPI_NOR_HAS_LOCK) },
 
 	{ "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },
 };
 
-static void atmel_default_init(struct spi_nor *nor)
-{
-	nor->flags |= SNOR_F_HAS_LOCK;
-}
-
-static const struct spi_nor_fixups atmel_fixups = {
-	.default_init = atmel_default_init,
-};
-
 const struct spi_nor_manufacturer spi_nor_atmel = {
 	.name = "atmel",
 	.parts = atmel_parts,
 	.nparts = ARRAY_SIZE(atmel_parts),
-	.fixups = &atmel_fixups,
 };
-- 
2.20.1


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[PATCH v4 2/3] mtd: spi-nor: sst: remove global protection flag

[Michael Walle]

This is considered bad for the following reasons:
 (1) We only support the block protection with BPn bits for write
     protection. Not all SST parts support this.
 (2) Newly added flash chip will automatically inherit the "has
     locking" support and thus needs to explicitly tested. Better
     be opt-in instead of opt-out.
 (3) There are already supported flashes which doesn't support
     the locking scheme. So I assume this wasn't properly tested
     before adding that chip; which enforces my previous argument
     that locking support should be an opt-in.

Remove the global flag and add individual flags to all flashes
which supports BP locking. In particular the following flashes
don't support the BP scheme:
 - SST26VF016B
 - SST26WF016B
 - SST26VF064B

Signed-off-by: Michael Walle <michael@walle.cc>
---
changes since RFC:
 - none

 drivers/mtd/spi-nor/sst.c | 30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/drivers/mtd/spi-nor/sst.c b/drivers/mtd/spi-nor/sst.c
index e0af6d25d573..8b169fa4102a 100644
--- a/drivers/mtd/spi-nor/sst.c
+++ b/drivers/mtd/spi-nor/sst.c
@@ -11,26 +11,26 @@
 static const struct flash_info sst_parts[] = {
 	/* SST -- large erase sizes are "overlays", "sectors" are 4K */
 	{ "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024,  8,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst25vf080b", INFO(0xbf258e, 0, 64 * 1024, 16,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst25vf016b", INFO(0xbf2541, 0, 64 * 1024, 32,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst25vf032b", INFO(0xbf254a, 0, 64 * 1024, 64,
-			      SECT_4K | SST_WRITE) },
-	{ "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+	{ "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf512",  INFO(0xbf2501, 0, 64 * 1024,  1,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf010",  INFO(0xbf2502, 0, 64 * 1024,  2,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf020",  INFO(0xbf2503, 0, 64 * 1024,  4,
-			      SECT_4K | SST_WRITE) },
-	{ "sst25wf020a", INFO(0x621612, 0, 64 * 1024,  4, SECT_4K) },
-	{ "sst25wf040b", INFO(0x621613, 0, 64 * 1024,  8, SECT_4K) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+	{ "sst25wf020a", INFO(0x621612, 0, 64 * 1024,  4, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "sst25wf040b", INFO(0x621613, 0, 64 * 1024,  8, SECT_4K | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf040",  INFO(0xbf2504, 0, 64 * 1024,  8,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf080",  INFO(0xbf2505, 0, 64 * 1024, 16,
-			      SECT_4K | SST_WRITE) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
 	{ "sst26wf016b", INFO(0xbf2651, 0, 64 * 1024, 32,
 			      SECT_4K | SPI_NOR_DUAL_READ |
 			      SPI_NOR_QUAD_READ) },
@@ -127,11 +127,6 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
 	return ret;
 }
 
-static void sst_default_init(struct spi_nor *nor)
-{
-	nor->flags |= SNOR_F_HAS_LOCK;
-}
-
 static void sst_post_sfdp_fixups(struct spi_nor *nor)
 {
 	if (nor->info->flags & SST_WRITE)
@@ -139,7 +134,6 @@ static void sst_post_sfdp_fixups(struct spi_nor *nor)
 }
 
 static const struct spi_nor_fixups sst_fixups = {
-	.default_init = sst_default_init,
 	.post_sfdp = sst_post_sfdp_fixups,
 };
 
-- 
2.20.1


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[PATCH v4 3/3] mtd: spi-nor: keep lock bits if they are non-volatile

[Michael Walle]

Traditionally, linux unlocks the whole flash because there are legacy
devices which has the write protections bits set by default at startup.
If you actually want to use the flash protection bits, eg. because there
is a read-only part for a bootloader, this automatic unlocking is
harmful. If there is no hardware write protection in place (usually
called WP#), a startup of the kernel just discards this protection.

I've gone through the datasheets of all the flashes (except the Intel
ones where I could not find any datasheet nor reference) which supports
the unlocking feature and looked how the sector protection was
implemented. The currently supported flashes can be divided into the
following two categories:
 (1) block protection bits are non-volatile. Thus they keep their values
     at reset and power-cycle
 (2) flashes where these bits are volatile. After reset or power-cycle,
     the whole memory array is protected.
     (a) some devices needs a special "Global Unprotect" command, eg.
         the Atmel AT25DF041A.
     (b) some devices require to clear the BPn bits in the status
         register.

Due to the reasons above, we do not want to clear the bits for flashes
which belong to category (1). Fortunately for us, only Atmel flashes
fall into category (2a). Implement the "Global Protect" and "Global
Unprotect" commands for these. For (2b) we can use normal block
protection locking scheme.

This patch adds a new flag to indicate the case (2). Only if we have
such a flash we unlock the whole flash array. To be backwards compatible
it also introduces a kernel configuration option which restores the
complete legacy behavior ("Disable write protection on any flashes").
Hopefully, this will clean up "unlock the entire flash for legacy
devices" once and for all.

For reference here are the actually commits which introduced the legacy
behaviour (and extended the behaviour to other chip manufacturers):

commit f80e521c916cb ("mtd: m25p80: add support for the Intel/Numonyx {16,32,64}0S33B SPI flash chips")
commit ea60658a08f8f ("mtd: m25p80: disable SST software protection bits by default")
commit 7228982442365 ("[MTD] m25p80: fix bug - ATmel spi flash fails to be copied to")

Actually, this might also fix handling of the Atmel AT25DF flashes,
because the original commit 7228982442365 ("[MTD] m25p80: fix bug -
ATmel spi flash fails to be copied to") was writing a 0 to the status
register, which is a "Global Unprotect". This might not be the case in
the current code which only handles the block protection bits BP2, BP1
and BP0. Thus, it depends on the current contents of the status register
if this unlock actually corresponds to a "Global Unprotect" command. In
the worst case, the current code might leave the AT25DF flashes in a
write protected state.

The commit 191f5c2ed4b6f ("mtd: spi-nor: use 16-bit WRR command when QE
is set on spansion flashes") changed that behaviour by just clearing BP2
to BP0 instead of writing a 0 to the status register.

Further, the commit 3e0930f109e76 ("mtd: spi-nor: Rework the disabling
of block write protection") expanded the unlock_all() feature to ANY
flash which supports locking.

Signed-off-by: Michael Walle <michael@walle.cc>
---
changes since v3:
 - now defaulting to MTD_SPI_NOR_WP_DISABLE_ON_VOLATILE, suggested by Vignesh
 - restored the original spi_nor_unlock_all(), instead add individual
   locking ops for the "Global Protect" scheme in atmel.c. This was tested
   partly with the AT25SL321 (for the test I added the fixups to this
   flash).
 - renamed SPI_NOR_UNPROTECT to SPI_NOR_WP_IS_VOLATILE. Suggested by
   Vingesh, although I've renamed it to a more general "WP_IS_VOLATILE"
   because either the BP bits or the individual sector locks might be
   volatile.
 - add mention of both block protection bits and "Global Unprotect" command
   in the Kconfig help text.

changes since v2:
 - add Kconfig option to be able to retain legacy behaviour
 - rebased the patch due to the spi-nor rewrite
 - dropped the Fixes: tag, it doens't make sense after the spi-nor rewrite
 - mention commit 3e0930f109e76 which further modified the unlock
   behaviour.

changes since v1:
 - completely rewrote patch, the first version used a device tree flag

 drivers/mtd/spi-nor/Kconfig |  42 ++++++++++++++
 drivers/mtd/spi-nor/atmel.c | 111 +++++++++++++++++++++++++++++++++---
 drivers/mtd/spi-nor/core.c  |  36 ++++++++----
 drivers/mtd/spi-nor/core.h  |   8 +++
 drivers/mtd/spi-nor/esmt.c  |   8 ++-
 drivers/mtd/spi-nor/intel.c |   6 +-
 drivers/mtd/spi-nor/sst.c   |  21 +++----
 7 files changed, 199 insertions(+), 33 deletions(-)

diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
index ffc4b380f2b1..11e6658ee85d 100644
--- a/drivers/mtd/spi-nor/Kconfig
+++ b/drivers/mtd/spi-nor/Kconfig
@@ -24,6 +24,48 @@ config MTD_SPI_NOR_USE_4K_SECTORS
 	  Please note that some tools/drivers/filesystems may not work with
 	  4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).
 
+choice
+	prompt "Write protection at boot"
+	default MTD_SPI_NOR_WP_DISABLE_ON_VOLATILE
+
+config MTD_SPI_NOR_WP_DISABLE
+	bool "Disable WP on any flashes (legacy behaviour)"
+	help
+	  This option disables the write protection on any SPI flashes at
+	  boot-up.
+
+	  Depending on the flash chip this either clears the block protection
+	  bits or does a "Global Unprotect" command.
+
+	  Don't use this if you intent to use the write protection of your
+	  SPI flash. This is only to keep backwards compatibility.
+
+config MTD_SPI_NOR_WP_DISABLE_ON_VOLATILE
+	bool "Disable WP on flashes w/ volatile protection bits"
+	help
+	  Some SPI flashes have volatile block protection bits, ie. after a
+	  power-up or a reset the flash is write protected by default.
+
+	  This option disables the write protection for these kind of flashes
+	  while keeping it enabled for any other SPI flashes which have
+	  non-volatile write protection bits.
+
+	  If the write protection will be disabled depending on the flash
+	  either the block protection bits are cleared or a "Global Unprotect"
+	  command is issued.
+
+	  If you are unsure, select this option.
+
+config MTD_SPI_NOR_WP_KEEP
+	bool "Keep write protection as is"
+	help
+	  If you select this option the write protection of any SPI flashes
+	  will not be changed. If your flash is write protected or will be
+	  automatically write protected after power-up you have to manually
+	  unlock it before you are able to write to it.
+
+endchoice
+
 source "drivers/mtd/spi-nor/controllers/Kconfig"
 
 endif # MTD_SPI_NOR
diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
index 49d392c6c8bc..9c3bd391cb32 100644
--- a/drivers/mtd/spi-nor/atmel.c
+++ b/drivers/mtd/spi-nor/atmel.c
@@ -8,23 +8,120 @@
 
 #include "core.h"
 
+#define ATMEL_SR_GLOBAL_PROTECT_MASK GENMASK(5, 2)
+
+/**
+ * atmel_set_global_protection - Do a Global Protect or Unprotect command
+ * @nor:	pointer to 'struct spi_nor'
+ * @ofs:	offset in bytes
+ * @len:	len in bytes
+ * @is_protect:	if true do a Global Protect otherwise it is a Global Unprotect
+ *
+ * Return: 0 on success, -error otherwise.
+ */
+static int atmel_set_global_protection(struct spi_nor *nor, loff_t ofs,
+				       uint64_t len, bool is_protect)
+{
+	int ret;
+	u8 sr;
+
+	/* We only support locking the whole flash array */
+	if (ofs || len != nor->params->size)
+		return -EINVAL;
+
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+	sr = nor->bouncebuf[0];
+
+	/* SRWD bit needs to be cleared, otherwise the protection doesn't change */
+	if (sr & SR_SRWD) {
+		sr &= ~SR_SRWD;
+		ret = spi_nor_write_sr_and_check(nor, sr);
+		if (ret) {
+			dev_err(nor->dev, "unable to clear SRWD bit, WP# asserted?\n");
+			return ret;
+		}
+	}
+
+	if (is_protect)
+		sr |= ATMEL_SR_GLOBAL_PROTECT_MASK;
+	else
+		sr &= ~ATMEL_SR_GLOBAL_PROTECT_MASK;
+
+	return spi_nor_write_sr_and_check(nor, sr);
+}
+
+static int atmel_global_protect(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+	return atmel_set_global_protection(nor, ofs, len, true);
+}
+
+static int atmel_global_unprotect(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+	return atmel_set_global_protection(nor, ofs, len, false);
+}
+
+static int atmel_is_global_protected(struct spi_nor *nor, loff_t ofs, uint64_t len)
+{
+	int ret;
+
+	if (ofs >= nor->params->size || (ofs + len) > nor->params->size)
+		return -EINVAL;
+
+	ret = spi_nor_read_sr(nor, nor->bouncebuf);
+	if (ret)
+		return ret;
+
+	return ((nor->bouncebuf[0] & ATMEL_SR_GLOBAL_PROTECT_MASK) == ATMEL_SR_GLOBAL_PROTECT_MASK);
+}
+
+static const struct spi_nor_locking_ops atmel_global_protection_ops = {
+	.lock = atmel_global_protect,
+	.unlock = atmel_global_unprotect,
+	.is_locked = atmel_is_global_protected,
+};
+
+void atmel_global_protection_default_init(struct spi_nor *nor)
+{
+	nor->params->locking_ops = &atmel_global_protection_ops;
+}
+
+static const struct spi_nor_fixups atmel_global_protection_fixups = {
+	.default_init = atmel_global_protection_default_init,
+};
+
 static const struct flash_info atmel_parts[] = {
 	/* Atmel -- some are (confusingly) marketed as "DataFlash" */
 	{ "at25fs010",  INFO(0x1f6601, 0, 32 * 1024,   4, SECT_4K | SPI_NOR_HAS_LOCK) },
 	{ "at25fs040",  INFO(0x1f6604, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK) },
 
-	{ "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8, SECT_4K | SPI_NOR_HAS_LOCK) },
-	{ "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64, SECT_4K | SPI_NOR_HAS_LOCK) },
-	{ "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64, SECT_4K | SPI_NOR_HAS_LOCK) },
-	{ "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at25df041a", INFO(0x1f4401, 0, 64 * 1024,   8,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
+	{ "at25df321",  INFO(0x1f4700, 0, 64 * 1024,  64,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
+	{ "at25df321a", INFO(0x1f4701, 0, 64 * 1024,  64,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
+	{ "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
 
 	{ "at25sl321",	INFO(0x1f4216, 0, 64 * 1024, 64,
 			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 
 	{ "at26f004",   INFO(0x1f0400, 0, 64 * 1024,  8, SECT_4K) },
-	{ "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K | SPI_NOR_HAS_LOCK) },
-	{ "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K | SPI_NOR_HAS_LOCK) },
-	{ "at26df321",  INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K | SPI_NOR_HAS_LOCK) },
+	{ "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
+	{ "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
+	{ "at26df321",  INFO(0x1f4700, 0, 64 * 1024, 64,
+			     SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE)
+			.fixups = &atmel_global_protection_fixups },
 
 	{ "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },
 };
diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 2add4a01fce2..c40a7c1490d7 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -276,7 +276,7 @@ int spi_nor_write_disable(struct spi_nor *nor)
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
+int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
 {
 	int ret;
 
@@ -906,7 +906,7 @@ static int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
  *
  * Return: 0 on success, -errno otherwise.
  */
-static int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
+int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
 {
 	if (nor->flags & SNOR_F_HAS_16BIT_SR)
 		return spi_nor_write_16bit_sr_and_check(nor, sr1);
@@ -2919,15 +2919,14 @@ static int spi_nor_quad_enable(struct spi_nor *nor)
  * spi_nor_unlock_all() - Unlocks the entire flash memory array.
  * @nor:	pointer to a 'struct spi_nor'.
  *
- * Some SPI NOR flashes are write protected by default after a power-on reset
- * cycle, in order to avoid inadvertent writes during power-up. Backward
- * compatibility imposes to unlock the entire flash memory array at power-up
- * by default.
+ * Return: 0 on success, -errno otherwise.
  */
 static int spi_nor_unlock_all(struct spi_nor *nor)
 {
-	if (nor->flags & SNOR_F_HAS_LOCK)
+	if (nor->flags & SNOR_F_HAS_LOCK) {
+		dev_dbg(nor->dev, "unprotecting entire flash\n");
 		return spi_nor_unlock(&nor->mtd, 0, nor->params->size);
+	}
 
 	return 0;
 }
@@ -2942,10 +2941,23 @@ static int spi_nor_init(struct spi_nor *nor)
 		return err;
 	}
 
-	err = spi_nor_unlock_all(nor);
-	if (err) {
-		dev_dbg(nor->dev, "Failed to unlock the entire flash memory array\n");
-		return err;
+	/*
+	 * Some SPI NOR flashes are write protected by default after a power-on
+	 * reset cycle, in order to avoid inadvertent writes during power-up.
+	 * Backward compatibility imposes to unlock the entire flash memory
+	 * array at power-up by default. Depending on the kernel configuration
+	 * (1) we do nothing, (2) we unlock the entire flash in any case or (3)
+	 * just do it actually powers up write-protected. The latter is
+	 * indicated by SNOR_F_WP_IS_VOLATILE.
+	 */
+	if (IS_ENABLED(CONFIG_MTD_SPI_NOR_WP_DISABLE) ||
+	    (IS_ENABLED(CONFIG_MTD_SPI_NOR_WP_DISABLE_ON_VOLATILE) &&
+	     nor->flags & SNOR_F_WP_IS_VOLATILE)) {
+		err = spi_nor_unlock_all(nor);
+		if (err) {
+			dev_err(nor->dev, "Failed to unlock the entire flash memory array\n");
+			return err;
+		}
 	}
 
 	if (nor->addr_width == 4 && !(nor->flags & SNOR_F_4B_OPCODES)) {
@@ -3170,6 +3182,8 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 		nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
 	if (info->flags & USE_CLSR)
 		nor->flags |= SNOR_F_USE_CLSR;
+	if (info->flags & SPI_NOR_WP_IS_VOLATILE)
+		nor->flags |= SNOR_F_WP_IS_VOLATILE;
 
 	if (info->flags & SPI_NOR_4BIT_BP) {
 		nor->flags |= SNOR_F_HAS_4BIT_BP;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 6f2f6b27173f..99dd2e14142a 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -26,6 +26,7 @@ enum spi_nor_option_flags {
 	SNOR_F_HAS_SR_TB_BIT6	= BIT(11),
 	SNOR_F_HAS_4BIT_BP      = BIT(12),
 	SNOR_F_HAS_SR_BP3_BIT6  = BIT(13),
+	SNOR_F_WP_IS_VOLATILE	= BIT(14),
 };
 
 struct spi_nor_read_command {
@@ -311,6 +312,11 @@ struct flash_info {
 					 * BP3 is bit 6 of status register.
 					 * Must be used with SPI_NOR_4BIT_BP.
 					 */
+#define SPI_NOR_WP_IS_VOLATILE	BIT(19)	/*
+					 * Flash has volatile write protection
+					 * bits. Usually these will power-up in
+					 * a write-protected state.
+					 */
 
 	/* Part specific fixup hooks. */
 	const struct spi_nor_fixups *fixups;
@@ -409,6 +415,8 @@ void spi_nor_unlock_and_unprep(struct spi_nor *nor);
 int spi_nor_sr1_bit6_quad_enable(struct spi_nor *nor);
 int spi_nor_sr2_bit1_quad_enable(struct spi_nor *nor);
 int spi_nor_sr2_bit7_quad_enable(struct spi_nor *nor);
+int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1);
+int spi_nor_read_sr(struct spi_nor *nor, u8 *sr);
 
 int spi_nor_xread_sr(struct spi_nor *nor, u8 *sr);
 ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
diff --git a/drivers/mtd/spi-nor/esmt.c b/drivers/mtd/spi-nor/esmt.c
index c93170008118..c2ebf29d95f2 100644
--- a/drivers/mtd/spi-nor/esmt.c
+++ b/drivers/mtd/spi-nor/esmt.c
@@ -11,9 +11,13 @@
 static const struct flash_info esmt_parts[] = {
 	/* ESMT */
 	{ "f25l32pa", INFO(0x8c2016, 0, 64 * 1024, 64,
-			   SECT_4K | SPI_NOR_HAS_LOCK) },
+			   SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "f25l32qa", INFO(0x8c4116, 0, 64 * 1024, 64,
-			   SECT_4K | SPI_NOR_HAS_LOCK) },
+			   SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
+	/*
+	 * According to the datasheet the BPn bits are non-volatile, whereas
+	 * they are volatile for the smaller f25l32qa.
+	 */
 	{ "f25l64qa", INFO(0x8c4117, 0, 64 * 1024, 128,
 			   SECT_4K | SPI_NOR_HAS_LOCK) },
 };
diff --git a/drivers/mtd/spi-nor/intel.c b/drivers/mtd/spi-nor/intel.c
index d8196f101368..c45ea0ad01f0 100644
--- a/drivers/mtd/spi-nor/intel.c
+++ b/drivers/mtd/spi-nor/intel.c
@@ -10,9 +10,9 @@
 
 static const struct flash_info intel_parts[] = {
 	/* Intel/Numonyx -- xxxs33b */
-	{ "160s33b",  INFO(0x898911, 0, 64 * 1024,  32, 0) },
-	{ "320s33b",  INFO(0x898912, 0, 64 * 1024,  64, 0) },
-	{ "640s33b",  INFO(0x898913, 0, 64 * 1024, 128, 0) },
+	{ "160s33b",  INFO(0x898911, 0, 64 * 1024,  32, SPI_NOR_WP_IS_VOLATILE) },
+	{ "320s33b",  INFO(0x898912, 0, 64 * 1024,  64, SPI_NOR_WP_IS_VOLATILE) },
+	{ "640s33b",  INFO(0x898913, 0, 64 * 1024, 128, SPI_NOR_WP_IS_VOLATILE) },
 };
 
 static void intel_default_init(struct spi_nor *nor)
diff --git a/drivers/mtd/spi-nor/sst.c b/drivers/mtd/spi-nor/sst.c
index 8b169fa4102a..5e4450877d66 100644
--- a/drivers/mtd/spi-nor/sst.c
+++ b/drivers/mtd/spi-nor/sst.c
@@ -11,26 +11,27 @@
 static const struct flash_info sst_parts[] = {
 	/* SST -- large erase sizes are "overlays", "sectors" are 4K */
 	{ "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024,  8,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25vf080b", INFO(0xbf258e, 0, 64 * 1024, 16,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25vf016b", INFO(0xbf2541, 0, 64 * 1024, 32,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25vf032b", INFO(0xbf254a, 0, 64 * 1024, 64,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
-	{ "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
+	{ "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128,
+			      SECT_4K | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25wf512",  INFO(0xbf2501, 0, 64 * 1024,  1,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25wf010",  INFO(0xbf2502, 0, 64 * 1024,  2,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25wf020",  INFO(0xbf2503, 0, 64 * 1024,  4,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25wf020a", INFO(0x621612, 0, 64 * 1024,  4, SECT_4K | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf040b", INFO(0x621613, 0, 64 * 1024,  8, SECT_4K | SPI_NOR_HAS_LOCK) },
 	{ "sst25wf040",  INFO(0xbf2504, 0, 64 * 1024,  8,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst25wf080",  INFO(0xbf2505, 0, 64 * 1024, 16,
-			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },
+			      SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK | SPI_NOR_WP_IS_VOLATILE) },
 	{ "sst26wf016b", INFO(0xbf2651, 0, 64 * 1024, 32,
 			      SECT_4K | SPI_NOR_DUAL_READ |
 			      SPI_NOR_QUAD_READ) },
-- 
2.20.1


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