[PATCH v2 00/27] mtd: spi-nor: Enhance software protection

[PATCH v2 00/27] mtd: spi-nor: Enhance software protection

[Miquel Raynal]

Hello,

As recently raised on the mailing-list (link below), it seems that the
"locking" support in SPI NOR could benefit from some enhancements. As I
myself had to dig into it recently, here is a proposal.

First issue that I see, the MEMLOCK ioctl is not behaving correctly
in some cases, as addressed in:

    mtd: spi-nor: swp: Improve locking user experience

Then there is no clear explanation of the shortcuts taken by the kernel
in terms of uAPI, so there is an attempt to list them in:

    mtd: spi-nor: swp: Explain the MEMLOCK ioctl implementation behaviour

Plus, Tudor also asked if we could cover locking in the testing
procedure, which is done in:

    mtd: spi-nor: Add steps for testing locking support

In order to simplify this procedure, and because it got very helpful
during my testing/development, I want to propose additions to the
debugfs output:

    mtd: spi-nor: debugfs: Add locking support TODO: make the captures again

Finally, I am providing an implementation for the complement (CMP)
feature in order to allow finer control of the regions locked. This
feature is for instance available on Winbond chips:

    [core] mtd: spi-nor: swp: Add support for the complement feature
    [doc]  mtd: spi-nor: Add steps for testing locking with CMP
    [use]  mtd: spi-nor: winbond: Add CMP locking support

Disclaimer: it was much less straightforward than I initially thought to
get the CMP feature working correctly. I tested it with as much focus as
I could, and I am improving the test coverage for the new cases, I am
also providing extra test cases in the metadata of the commit (which do
not make sense to test for chip additions, but may be sensible show when
making core additions like this one), but honestly there are so many
possibilities, I may still be missing corner cases. I hope this will
anyway be helpful to others!

All the other patches are misc improvements or style fixes which I faced
and fixed during my development.

Link: https://lore.kernel.org/linux-mtd/92e99a96-5582-48a5-a4f9-e9b33fcff171@linux.dev/

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Changes in v2:
- Collect tags.
- Add missing Fixes/Cc: stable tags.
- Add a comment explaining why can_be_top && can_be_bottom is a specific
  condition.
- Fix commit logs following Michael Walle's reviews.
- Amend the documentation following our discussion with Michael Walle as
  well.
- Cache the SR register for debugfs use.
- Create a locked sector map file instead of dumping it as part of the
  `params` file output.
- Improved greatly the output of the map as suggested by Michael.
- Add a patch fixing a duplicate dependency in Kconfig.
- Add an important comment in the doc about the small 4kiB erase size
  choice.
- Add test runs for each and every chip for which the CMP feature is
  added. This prove me that testing of each and every chip was needed,
  as some of them seem to feature a broken BFPT table which does not
  advertise a working 35h (Read CR) command.
- Added a condition on which the CMP feature is enabled: RDCR must be
  possible.
- Link to v1: https://lore.kernel.org/r/20251114-winbond-v6-18-rc1-spi-nor-swp-v1-0-487bc7129931@bootlin.com

---
Miquel Raynal (27):
      mtd: spi-nor: Drop duplicate Kconfig dependency
      mtd: spi-nor: debugfs: Fix the flags list
      mtd: spi-nor: swp: Improve locking user experience
      mtd: spi-nor: Improve opcodes documentation
      mtd: spi-nor: debugfs: Align variable access with the rest of the file
      mtd: spi-nor: debugfs: Enhance output
      mtd: spi-nor: swp: Explain the MEMLOCK ioctl implementation behaviour
      mtd: spi-nor: swp: Clarify a comment
      mtd: spi-nor: swp: Use a pointer for SR instead of a single byte
      mtd: spi-nor: swp: Create a helper that writes SR, CR and checks
      mtd: spi-nor: swp: Rename a mask
      mtd: spi-nor: swp: Create a TB intermediate variable
      mtd: spi-nor: swp: Create helpers for building the SR register
      mtd: spi-nor: swp: Simplify checking the locked/unlocked range
      mtd: spi-nor: swp: Cosmetic changes
      mtd: spi-nor: Create a local SR cache
      mtd: spi-nor: debugfs: Add locking support
      mtd: spi-nor: debugfs: Add a locked sectors map
      mtd: spi-nor: Add steps for testing locking support
      mtd: spi-nor: swp: Add support for the complement feature
      mtd: spi-nor: Add steps for testing locking with CMP
      mtd: spi-nor: winbond: Add W25H512NWxxAM CMP locking support
      mtd: spi-nor: winbond: Add W25H01NWxxAM CMP locking support
      mtd: spi-nor: winbond: Add W25H02NWxxAM CMP locking support
      mtd: spi-nor: winbond: Add W25H01NWxxIQ CMP locking support
      mtd: spi-nor: winbond: Add W25Q01NWxxIM CMP locking support
      mtd: spi-nor: winbond: Add W25Q02NWxxIM CMP locking support

 Documentation/driver-api/mtd/spi-nor.rst | 164 ++++++++++++++
 drivers/mtd/spi-nor/Kconfig              |   1 -
 drivers/mtd/spi-nor/core.c               |  74 ++++++-
 drivers/mtd/spi-nor/core.h               |  10 +
 drivers/mtd/spi-nor/debugfs.c            |  63 +++++-
 drivers/mtd/spi-nor/swp.c                | 359 ++++++++++++++++++++++++-------
 drivers/mtd/spi-nor/winbond.c            |  41 +++-
 include/linux/mtd/spi-nor.h              |   7 +-
 8 files changed, 631 insertions(+), 88 deletions(-)
---
base-commit: 99bb09369a9eaed5de0e647cc1aab215668ddc6f
change-id: 20251114-winbond-v6-18-rc1-spi-nor-swp-865d36f4f695

Best regards,
-- 
Miquel Raynal <miquel.raynal@bootlin.com>

[PATCH v2 01/27] mtd: spi-nor: Drop duplicate Kconfig dependency

[Miquel Raynal]

I do not think the MTD dependency is needed twice. This is likely a
duplicate coming from a former rebase when the spi-nor core got cleaned
up a while ago. Remove the extra line.

Fixes: b35b9a10362d ("mtd: spi-nor: Move m25p80 code in spi-nor.c")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
index 24cd25de2b8b..fd05a24d64a9 100644
--- a/drivers/mtd/spi-nor/Kconfig
+++ b/drivers/mtd/spi-nor/Kconfig
@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 menuconfig MTD_SPI_NOR
 	tristate "SPI NOR device support"
-	depends on MTD
 	depends on MTD && SPI_MASTER
 	select SPI_MEM
 	help

-- 
2.51.1

[PATCH v2 02/27] mtd: spi-nor: debugfs: Fix the flags list

[Miquel Raynal]

As mentioned above the spi_nor_option_flags enumeration in core.h, this
list should be kept in sync with the one in the core.

Add the missing flag.

Fixes: 6a42bc97ccda ("mtd: spi-nor: core: Allow specifying the byte order in Octal DTR mode")
Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/debugfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index fa6956144d2e..d700e0b27182 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -28,6 +28,7 @@ static const char *const snor_f_names[] = {
 	SNOR_F_NAME(RWW),
 	SNOR_F_NAME(ECC),
 	SNOR_F_NAME(NO_WP),
+	SNOR_F_NAME(SWAP16),
 };
 #undef SNOR_F_NAME
 

-- 
2.51.1

[PATCH v2 03/27] mtd: spi-nor: swp: Improve locking user experience

[Miquel Raynal]

In the case of the first block being locked (or the few first blocks),
if the user want to fully unlock the device it has two possibilities:
- either it asks to unlock the entire device, and this works;
- or it asks to unlock just the block(s) that are currently locked,
  which fails.

It fails because the conditions "can_be_top" and "can_be_bottom" are
true. Indeed, in this case, we unlock everything, so the TB bit does not
matter. However in the current implementation, use_top would be true (as
this is the favourite option) and lock_len, which in practice should be
reduced down to 0, is set to "nor->params->size - (ofs + len)" which is
a positive number. This is wrong.

An easy way is to simply add an extra condition. In the unlock() path,
if we can achieve the same result from both sides, it means we unlock
everything and lock_len must simply be 0. A comment is added to clarify
that logic.

Fixes: 3dd8012a8eeb ("mtd: spi-nor: add TB (Top/Bottom) protect support")
Cc: stable@kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 9b07f83aeac7..1d50db1ef1a0 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -280,8 +280,15 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	/* Prefer top, if both are valid */
 	use_top = can_be_top;
 
-	/* lock_len: length of region that should remain locked */
-	if (use_top)
+	/*
+	 * lock_len: length of region that should remain locked.
+	 *
+	 * When can_be_top and can_be_bottom booleans are true, both adjacent
+	 * regions are unlocked, thus the entire flash can be unlocked.
+	 */
+	if (can_be_top && can_be_bottom)
+		lock_len = 0;
+	else if (use_top)
 		lock_len = nor->params->size - (ofs + len);
 	else
 		lock_len = ofs;

-- 
2.51.1

[PATCH v2 04/27] mtd: spi-nor: Improve opcodes documentation

[Miquel Raynal]

There are two status registers, named 1 and 2. The current wording is
misleading as "1" may refer to the status register ID as well as the
number of bytes required (which, in this case can be 1 or 2).

Clarify the comments by aligning them on the same pattern:
"{read,write} status {1,2} register"

Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 include/linux/mtd/spi-nor.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index cdcfe0fd2e7d..90a0cf583512 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -21,8 +21,8 @@
 /* Flash opcodes. */
 #define SPINOR_OP_WRDI		0x04	/* Write disable */
 #define SPINOR_OP_WREN		0x06	/* Write enable */
-#define SPINOR_OP_RDSR		0x05	/* Read status register */
-#define SPINOR_OP_WRSR		0x01	/* Write status register 1 byte */
+#define SPINOR_OP_RDSR		0x05	/* Read status register 1 */
+#define SPINOR_OP_WRSR		0x01	/* Write status register 1 */
 #define SPINOR_OP_RDSR2		0x3f	/* Read status register 2 */
 #define SPINOR_OP_WRSR2		0x3e	/* Write status register 2 */
 #define SPINOR_OP_READ		0x03	/* Read data bytes (low frequency) */

-- 
2.51.1

[PATCH v2 05/27] mtd: spi-nor: debugfs: Align variable access with the rest of the file

[Miquel Raynal]

The "params" variable is used everywhere else, align this particular
line of the file to use "params" directly rather than the "nor" pointer.

Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index d700e0b27182..69830ad43990 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -139,7 +139,7 @@ static int spi_nor_params_show(struct seq_file *s, void *data)
 
 	if (!(nor->flags & SNOR_F_NO_OP_CHIP_ERASE)) {
 		string_get_size(params->size, 1, STRING_UNITS_2, buf, sizeof(buf));
-		seq_printf(s, " %02x (%s)\n", nor->params->die_erase_opcode, buf);
+		seq_printf(s, " %02x (%s)\n", params->die_erase_opcode, buf);
 	}
 
 	seq_puts(s, "\nsector map\n");

-- 
2.51.1

[PATCH v2 06/27] mtd: spi-nor: debugfs: Enhance output

[Miquel Raynal]

Align the number of dashes to the bigger column width (the title in this
case) to make the output more pleasant and aligned with what is done
in the "params" file output.

Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/debugfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index 69830ad43990..d0191eb9f879 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -144,7 +144,7 @@ static int spi_nor_params_show(struct seq_file *s, void *data)
 
 	seq_puts(s, "\nsector map\n");
 	seq_puts(s, " region (in hex)   | erase mask | overlaid\n");
-	seq_puts(s, " ------------------+------------+----------\n");
+	seq_puts(s, " ------------------+------------+---------\n");
 	for (i = 0; i < erase_map->n_regions; i++) {
 		u64 start = region[i].offset;
 		u64 end = start + region[i].size - 1;

-- 
2.51.1

[PATCH v2 07/27] mtd: spi-nor: swp: Explain the MEMLOCK ioctl implementation behaviour

[Miquel Raynal]

Add comments about how these requests are actually handled in the SPI
NOR core. Their behaviour was not entirely clear to me at first, and
explaining them in plain English sounds the way to go.

Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 1d50db1ef1a0..64a917543928 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -346,6 +346,14 @@ static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, u64 len)
 	return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]);
 }
 
+/*
+ * These ioctls behave according to the following rules:
+ * ->lock(): Never locks more than what is requested, ie. may lock less
+ * ->unlock(): Never unlocks more than what is requested, ie. may unlock less
+ * -is_locked(): Checks if the region is *fully* locked, returns false otherwise.
+ *               This feeback may be misleading because users may get an "unlocked"
+ *               status even though a subpart of the region is effectively locked.
+ */
 static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = {
 	.lock = spi_nor_sr_lock,
 	.unlock = spi_nor_sr_unlock,

-- 
2.51.1

[PATCH v2 08/27] mtd: spi-nor: swp: Clarify a comment

[Miquel Raynal]

The comment states that some power of two sizes are not supported. This
is very device dependent (based on the size), so modulate a bit the
sentence to make it more accurate.

Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 64a917543928..246f6d5ca8dd 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -303,7 +303,7 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
 			val = (val & ~SR_BP3) | SR_BP3_BIT6;
 
-		/* Some power-of-two sizes are not supported */
+		/* Some power-of-two sizes may not be supported */
 		if (val & ~mask)
 			return -EINVAL;
 	}

-- 
2.51.1

[PATCH v2 09/27] mtd: spi-nor: swp: Use a pointer for SR instead of a single byte

[Miquel Raynal]

At this stage, the Status Register is most often seen as a single
byte. This is subject to change when we will need to read the CMP bit
which is located in the Control Register (kind of secondary status
register). Both will need to be carried.

Change a few prototypes to carry a u8 pointer. This way it also makes it
very clear where we access the first register, and where we will access
the second.

There is no functional change.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 48 ++++++++++++++++++++++++-----------------------
 1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 246f6d5ca8dd..af6e577d9b42 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -53,13 +53,13 @@ static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
 		return sector_size;
 }
 
-static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
+static void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_t *ofs,
 					u64 *len)
 {
 	u64 min_prot_len;
 	u8 mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
-	u8 bp, val = sr & mask;
+	u8 bp, val = sr[0] & mask;
 
 	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
 		val = (val & ~SR_BP3_BIT6) | SR_BP3;
@@ -79,7 +79,7 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
 	if (*len > nor->params->size)
 		*len = nor->params->size;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB && sr & tb_mask)
+	if (nor->flags & SNOR_F_HAS_SR_TB && sr[0] & tb_mask)
 		*ofs = 0;
 	else
 		*ofs = nor->params->size - *len;
@@ -90,7 +90,7 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, u8 sr, loff_t *ofs,
  * (if @locked is false); false otherwise.
  */
 static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs,
-					 u64 len, u8 sr, bool locked)
+					 u64 len, const u8 *sr, bool locked)
 {
 	loff_t lock_offs, lock_offs_max, offs_max;
 	u64 lock_len;
@@ -111,13 +111,13 @@ static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs,
 		return (ofs >= lock_offs_max) || (offs_max <= lock_offs);
 }
 
-static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, u8 sr)
+static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, const u8 *sr)
 {
 	return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true);
 }
 
 static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, u64 len,
-				   u8 sr)
+				   const u8 *sr)
 {
 	return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false);
 }
@@ -158,7 +158,8 @@ static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, u64 len,
 static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 {
 	u64 min_prot_len;
-	int ret, status_old, status_new;
+	int ret;
+	u8 status_old[1] = {}, status_new[1] = {};
 	u8 mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
 	u8 pow, val;
@@ -170,7 +171,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (ret)
 		return ret;
 
-	status_old = nor->bouncebuf[0];
+	status_old[0] = nor->bouncebuf[0];
 
 	/* If nothing in our range is unlocked, we don't need to do anything */
 	if (spi_nor_is_locked_sr(nor, ofs, len, status_old))
@@ -215,7 +216,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 			return -EINVAL;
 	}
 
-	status_new = (status_old & ~mask & ~tb_mask) | val;
+	status_new[0] = (status_old[0] & ~mask & ~tb_mask) | val;
 
 	/*
 	 * Disallow further writes if WP# pin is neither left floating nor
@@ -223,20 +224,20 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	 * WP# pin hard strapped to GND can be a valid use case.
 	 */
 	if (!(nor->flags & SNOR_F_NO_WP))
-		status_new |= SR_SRWD;
+		status_new[0] |= SR_SRWD;
 
 	if (!use_top)
-		status_new |= tb_mask;
+		status_new[0] |= tb_mask;
 
 	/* Don't bother if they're the same */
-	if (status_new == status_old)
+	if (status_new[0] == status_old[0])
 		return 0;
 
 	/* Only modify protection if it will not unlock other areas */
-	if ((status_new & mask) < (status_old & mask))
+	if ((status_new[0] & mask) < (status_old[0] & mask))
 		return -EINVAL;
 
-	return spi_nor_write_sr_and_check(nor, status_new);
+	return spi_nor_write_sr_and_check(nor, status_new[0]);
 }
 
 /*
@@ -247,7 +248,8 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 {
 	u64 min_prot_len;
-	int ret, status_old, status_new;
+	int ret;
+	u8 status_old[1], status_new[1];
 	u8 mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
 	u8 pow, val;
@@ -259,7 +261,7 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (ret)
 		return ret;
 
-	status_old = nor->bouncebuf[0];
+	status_old[0] = nor->bouncebuf[0];
 
 	/* If nothing in our range is locked, we don't need to do anything */
 	if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old))
@@ -308,24 +310,24 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 			return -EINVAL;
 	}
 
-	status_new = (status_old & ~mask & ~tb_mask) | val;
+	status_new[0] = (status_old[0] & ~mask & ~tb_mask) | val;
 
 	/* Don't protect status register if we're fully unlocked */
 	if (lock_len == 0)
-		status_new &= ~SR_SRWD;
+		status_new[0] &= ~SR_SRWD;
 
 	if (!use_top)
-		status_new |= tb_mask;
+		status_new[0] |= tb_mask;
 
 	/* Don't bother if they're the same */
-	if (status_new == status_old)
+	if (status_new[0] == status_old[0])
 		return 0;
 
 	/* Only modify protection if it will not lock other areas */
-	if ((status_new & mask) > (status_old & mask))
+	if ((status_new[0] & mask) > (status_old[0] & mask))
 		return -EINVAL;
 
-	return spi_nor_write_sr_and_check(nor, status_new);
+	return spi_nor_write_sr_and_check(nor, status_new[0]);
 }
 
 /*
@@ -343,7 +345,7 @@ static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (ret)
 		return ret;
 
-	return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf[0]);
+	return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf);
 }
 
 /*

-- 
2.51.1

[PATCH v2 10/27] mtd: spi-nor: swp: Create a helper that writes SR, CR and checks

[Miquel Raynal]

There are many helpers already to either read and/or write SR and/or CR,
as well as sometimes check the returned values. In order to be able to
switch from a 1 byte status register to a 2 bytes status register while
keeping the same level of verification, let's introduce a new helper
that writes them both (atomically) and then reads them back (separated)
to compare the values.

In case 2 bytes registers are not supported, we still have the usual
fallback available in the helper being exported to the rest of the core.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/core.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++
 drivers/mtd/spi-nor/core.h |  1 +
 2 files changed, 66 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 8d91052cc21e..97da30d9f6c1 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -976,6 +976,54 @@ int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr)
 	return 0;
 }
 
+/**
+ * spi_nor_write_16bit_sr_cr_and_check() - Write the Status Register 1 and the
+ * Configuration Register in one shot. Ensure that the bytes written in both
+ * registers match the received value.
+ * @nor:	pointer to a 'struct spi_nor'.
+ * @regs:	two-byte array with values to be written to the status and
+ *		configuration registers.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_write_16bit_sr_cr_and_check(struct spi_nor *nor, const u8 *regs)
+{
+	u8 written_regs[2];
+	int ret;
+
+	written_regs[0] = regs[0];
+	written_regs[1] = regs[1];
+	nor->bouncebuf[0] = regs[0];
+	nor->bouncebuf[1] = regs[1];
+
+	ret = spi_nor_write_sr(nor, nor->bouncebuf, 2);
+	if (ret)
+		return ret;
+
+	ret = spi_nor_read_sr(nor, &nor->bouncebuf[0]);
+	if (ret)
+		return ret;
+
+	if (written_regs[0] != nor->bouncebuf[0]) {
+		dev_dbg(nor->dev, "SR: Read back test failed\n");
+		return -EIO;
+	}
+
+	if (nor->flags & SNOR_F_NO_READ_CR)
+		return 0;
+
+	ret = spi_nor_read_cr(nor, &nor->bouncebuf[1]);
+	if (ret)
+		return ret;
+
+	if (written_regs[1] != nor->bouncebuf[1]) {
+		dev_dbg(nor->dev, "CR: read back test failed\n");
+		return -EIO;
+	}
+
+	return 0;
+}
+
 /**
  * spi_nor_write_sr_and_check() - Write the Status Register 1 and ensure that
  * the byte written match the received value without affecting other bits in the
@@ -993,6 +1041,23 @@ int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1)
 	return spi_nor_write_sr1_and_check(nor, sr1);
 }
 
+/**
+ * spi_nor_write_sr_cr_and_check() - Write the Status Register 1 and ensure that
+ * the byte written match the received value. Same for the Control Register if
+ * available.
+ * @nor:	pointer to a 'struct spi_nor'.
+ * @regs:	byte array to be written to the registers.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+int spi_nor_write_sr_cr_and_check(struct spi_nor *nor, const u8 *regs)
+{
+	if (nor->flags & SNOR_F_HAS_16BIT_SR)
+		return spi_nor_write_16bit_sr_cr_and_check(nor, regs);
+
+	return spi_nor_write_sr1_and_check(nor, regs[0]);
+}
+
 /**
  * spi_nor_write_sr2() - Write the Status Register 2 using the
  * SPINOR_OP_WRSR2 (3eh) command.
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 16b382d4f04f..3dc9ba3bc6da 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -632,6 +632,7 @@ int spi_nor_read_cr(struct spi_nor *nor, u8 *cr);
 int spi_nor_write_sr(struct spi_nor *nor, const u8 *sr, size_t len);
 int spi_nor_write_sr_and_check(struct spi_nor *nor, u8 sr1);
 int spi_nor_write_16bit_cr_and_check(struct spi_nor *nor, u8 cr);
+int spi_nor_write_sr_cr_and_check(struct spi_nor *nor, const u8 *regs);
 
 ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
 			  u8 *buf);

-- 
2.51.1

[PATCH v2 11/27] mtd: spi-nor: swp: Rename a mask

[Miquel Raynal]

"mask" is not very descriptive when we already manipulate two masks, and
soon will manipulate three. Rename it "bp_mask" to align with the
existing "tb_mask" and soon "cmp_mask".

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index af6e577d9b42..66f85826ba0d 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -57,9 +57,9 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_
 					u64 *len)
 {
 	u64 min_prot_len;
-	u8 mask = spi_nor_get_sr_bp_mask(nor);
+	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
-	u8 bp, val = sr[0] & mask;
+	u8 bp, val = sr[0] & bp_mask;
 
 	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
 		val = (val & ~SR_BP3_BIT6) | SR_BP3;
@@ -160,7 +160,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	u64 min_prot_len;
 	int ret;
 	u8 status_old[1] = {}, status_new[1] = {};
-	u8 mask = spi_nor_get_sr_bp_mask(nor);
+	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
 	u8 pow, val;
 	loff_t lock_len;
@@ -199,7 +199,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 		lock_len = ofs + len;
 
 	if (lock_len == nor->params->size) {
-		val = mask;
+		val = bp_mask;
 	} else {
 		min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
@@ -208,15 +208,15 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
 			val = (val & ~SR_BP3) | SR_BP3_BIT6;
 
-		if (val & ~mask)
+		if (val & ~bp_mask)
 			return -EINVAL;
 
 		/* Don't "lock" with no region! */
-		if (!(val & mask))
+		if (!(val & bp_mask))
 			return -EINVAL;
 	}
 
-	status_new[0] = (status_old[0] & ~mask & ~tb_mask) | val;
+	status_new[0] = (status_old[0] & ~bp_mask & ~tb_mask) | val;
 
 	/*
 	 * Disallow further writes if WP# pin is neither left floating nor
@@ -234,7 +234,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 		return 0;
 
 	/* Only modify protection if it will not unlock other areas */
-	if ((status_new[0] & mask) < (status_old[0] & mask))
+	if ((status_new[0] & bp_mask) < (status_old[0] & bp_mask))
 		return -EINVAL;
 
 	return spi_nor_write_sr_and_check(nor, status_new[0]);
@@ -250,7 +250,7 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	u64 min_prot_len;
 	int ret;
 	u8 status_old[1], status_new[1];
-	u8 mask = spi_nor_get_sr_bp_mask(nor);
+	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
 	u8 pow, val;
 	loff_t lock_len;
@@ -306,11 +306,11 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 			val = (val & ~SR_BP3) | SR_BP3_BIT6;
 
 		/* Some power-of-two sizes may not be supported */
-		if (val & ~mask)
+		if (val & ~bp_mask)
 			return -EINVAL;
 	}
 
-	status_new[0] = (status_old[0] & ~mask & ~tb_mask) | val;
+	status_new[0] = (status_old[0] & ~bp_mask & ~tb_mask) | val;
 
 	/* Don't protect status register if we're fully unlocked */
 	if (lock_len == 0)
@@ -324,7 +324,7 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 		return 0;
 
 	/* Only modify protection if it will not lock other areas */
-	if ((status_new[0] & mask) > (status_old[0] & mask))
+	if ((status_new[0] & bp_mask) > (status_old[0] & bp_mask))
 		return -EINVAL;
 
 	return spi_nor_write_sr_and_check(nor, status_new[0]);

-- 
2.51.1

[PATCH v2 12/27] mtd: spi-nor: swp: Create a TB intermediate variable

[Miquel Raynal]

Ease the future reuse of the tb (Top/Bottom) boolean by creating an
intermediate variable.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 66f85826ba0d..f068cb9c8f6d 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -60,6 +60,7 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
 	u8 bp, val = sr[0] & bp_mask;
+	bool tb = (nor->flags & SNOR_F_HAS_SR_TB) ? sr[0] & tb_mask : 0;
 
 	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
 		val = (val & ~SR_BP3_BIT6) | SR_BP3;
@@ -79,7 +80,7 @@ static void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_
 	if (*len > nor->params->size)
 		*len = nor->params->size;
 
-	if (nor->flags & SNOR_F_HAS_SR_TB && sr[0] & tb_mask)
+	if (tb)
 		*ofs = 0;
 	else
 		*ofs = nor->params->size - *len;

-- 
2.51.1

[PATCH v2 13/27] mtd: spi-nor: swp: Create helpers for building the SR register

[Miquel Raynal]

The status register contains 3 or 4 BP (Block Protect) bits, 0 or 1
TB (Top/Bottom) bit, soon 0 or 1 CMP (Complement) bit. The last BP bit
and the TB bit locations change between vendors. The whole logic of
buildling the content of the status register based on some input
conditions is used two times and soon will be used 4 times.

Create dedicated helpers for these steps.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 83 +++++++++++++++++++++++++++++------------------
 1 file changed, 51 insertions(+), 32 deletions(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index f068cb9c8f6d..e2e423b20989 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -123,6 +123,43 @@ static bool spi_nor_is_unlocked_sr(struct spi_nor *nor, loff_t ofs, u64 len,
 	return spi_nor_check_lock_status_sr(nor, ofs, len, sr, false);
 }
 
+static int spi_nor_sr_set_bp_mask(struct spi_nor *nor, u8 *sr, u8 pow)
+{
+	u8 mask = spi_nor_get_sr_bp_mask(nor);
+	u8 val = pow << SR_BP_SHIFT;
+
+	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
+		val = (val & ~SR_BP3) | SR_BP3_BIT6;
+
+	if (val & ~mask)
+		return -EINVAL;
+
+	sr[0] = val;
+
+	return 0;
+}
+
+static int spi_nor_build_sr(struct spi_nor *nor, const u8 *old_sr, u8 *new_sr,
+			    u8 pow, bool use_top)
+{
+	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
+	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
+	int ret;
+
+	new_sr[0] = old_sr[0] & ~bp_mask & ~tb_mask;
+
+	/* Build BP field */
+	ret = spi_nor_sr_set_bp_mask(nor, &new_sr[0], pow);
+	if (ret)
+		return ret;
+
+	/* Build TB field */
+	if (!use_top)
+		new_sr[0] |= tb_mask;
+
+	return 0;
+}
+
 /*
  * Lock a region of the flash. Compatible with ST Micro and similar flash.
  * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status
@@ -162,11 +199,10 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	int ret;
 	u8 status_old[1] = {}, status_new[1] = {};
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
-	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
-	u8 pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
+	u8 pow;
 
 	ret = spi_nor_read_sr(nor, nor->bouncebuf);
 	if (ret)
@@ -200,24 +236,19 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 		lock_len = ofs + len;
 
 	if (lock_len == nor->params->size) {
-		val = bp_mask;
+		pow = (nor->flags & SNOR_F_HAS_4BIT_BP) ? GENMASK(3, 0) : GENMASK(2, 0);
 	} else {
 		min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
-		val = pow << SR_BP_SHIFT;
-
-		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
-			val = (val & ~SR_BP3) | SR_BP3_BIT6;
-
-		if (val & ~bp_mask)
-			return -EINVAL;
-
-		/* Don't "lock" with no region! */
-		if (!(val & bp_mask))
-			return -EINVAL;
 	}
 
-	status_new[0] = (status_old[0] & ~bp_mask & ~tb_mask) | val;
+	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top);
+	if (ret)
+		return ret;
+
+	/* Don't "lock" with no region! */
+	if (!(status_new[0] & bp_mask))
+		return -EINVAL;
 
 	/*
 	 * Disallow further writes if WP# pin is neither left floating nor
@@ -227,9 +258,6 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (!(nor->flags & SNOR_F_NO_WP))
 		status_new[0] |= SR_SRWD;
 
-	if (!use_top)
-		status_new[0] |= tb_mask;
-
 	/* Don't bother if they're the same */
 	if (status_new[0] == status_old[0])
 		return 0;
@@ -252,11 +280,10 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	int ret;
 	u8 status_old[1], status_new[1];
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
-	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
-	u8 pow, val;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
+	u8 pow;
 
 	ret = spi_nor_read_sr(nor, nor->bouncebuf);
 	if (ret)
@@ -297,29 +324,21 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 		lock_len = ofs;
 
 	if (lock_len == 0) {
-		val = 0; /* fully unlocked */
+		pow = 0; /* fully unlocked */
 	} else {
 		min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
-		val = pow << SR_BP_SHIFT;
 
-		if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3)
-			val = (val & ~SR_BP3) | SR_BP3_BIT6;
-
-		/* Some power-of-two sizes may not be supported */
-		if (val & ~bp_mask)
-			return -EINVAL;
 	}
 
-	status_new[0] = (status_old[0] & ~bp_mask & ~tb_mask) | val;
+	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top);
+	if (ret)
+		return ret;
 
 	/* Don't protect status register if we're fully unlocked */
 	if (lock_len == 0)
 		status_new[0] &= ~SR_SRWD;
 
-	if (!use_top)
-		status_new[0] |= tb_mask;
-
 	/* Don't bother if they're the same */
 	if (status_new[0] == status_old[0])
 		return 0;

-- 
2.51.1

[PATCH v2 14/27] mtd: spi-nor: swp: Simplify checking the locked/unlocked range

[Miquel Raynal]

In both the locking/unlocking steps, at the end we verify whether we do
not lock/unlock more than requested (in which case an error must be
returned).

While being possible to do that with very simple mask comparisons, it
does not scale when adding extra locking features such as the CMP
possibility. In order to make these checks slightly easier to read and
more future proof, use existing helpers to read the (future) status
register, extract the covered range, and compare it with very usual
algebric comparisons.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index e2e423b20989..c45a9ddd5788 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -198,7 +198,8 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	u64 min_prot_len;
 	int ret;
 	u8 status_old[1] = {}, status_new[1] = {};
-	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
+	loff_t ofs_old, ofs_new;
+	u64 len_old, len_new;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
@@ -246,10 +247,6 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (ret)
 		return ret;
 
-	/* Don't "lock" with no region! */
-	if (!(status_new[0] & bp_mask))
-		return -EINVAL;
-
 	/*
 	 * Disallow further writes if WP# pin is neither left floating nor
 	 * wrongly tied to GND (that includes internal pull-downs).
@@ -262,8 +259,16 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (status_new[0] == status_old[0])
 		return 0;
 
+	spi_nor_get_locked_range_sr(nor, status_old, &ofs_old, &len_old);
+	spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+
+	/* Don't "lock" with no region! */
+	if (!len_new)
+		return -EINVAL;
+
 	/* Only modify protection if it will not unlock other areas */
-	if ((status_new[0] & bp_mask) < (status_old[0] & bp_mask))
+	if (len_old &&
+	    (ofs_old < ofs_new || (ofs_new + len_new) < (ofs_old + len_old)))
 		return -EINVAL;
 
 	return spi_nor_write_sr_and_check(nor, status_new[0]);
@@ -279,7 +284,8 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	u64 min_prot_len;
 	int ret;
 	u8 status_old[1], status_new[1];
-	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
+	loff_t ofs_old, ofs_new;
+	u64 len_old, len_new;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
@@ -344,7 +350,10 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 		return 0;
 
 	/* Only modify protection if it will not lock other areas */
-	if ((status_new[0] & bp_mask) > (status_old[0] & bp_mask))
+	spi_nor_get_locked_range_sr(nor, status_old, &ofs_old, &len_old);
+	spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+	if (len_old && len_new &&
+	    (ofs_new < ofs_old || (ofs_old + len_old) < (ofs_new + len_new)))
 		return -EINVAL;
 
 	return spi_nor_write_sr_and_check(nor, status_new[0]);

-- 
2.51.1

[PATCH v2 15/27] mtd: spi-nor: swp: Cosmetic changes

[Miquel Raynal]

As a final preparation step for the introduction of CMP support, make
a few more cosmetic changes to simplify the reading of the diff when
adding the CMP feature. In particular, define "min_prot_len" earlier as
it will be reused and move the definition of the "ret" variable at the
end of the stack just because it looks better.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/swp.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index c45a9ddd5788..c3dbc8832025 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -195,14 +195,14 @@ static int spi_nor_build_sr(struct spi_nor *nor, const u8 *old_sr, u8 *new_sr,
  */
 static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 {
-	u64 min_prot_len;
-	int ret;
+	u64 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 	u8 status_old[1] = {}, status_new[1] = {};
 	loff_t ofs_old, ofs_new;
 	u64 len_old, len_new;
 	loff_t lock_len;
 	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
 	bool use_top;
+	int ret;
 	u8 pow;
 
 	ret = spi_nor_read_sr(nor, nor->bouncebuf);
@@ -236,12 +236,10 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	else
 		lock_len = ofs + len;
 
-	if (lock_len == nor->params->size) {
+	if (lock_len == nor->params->size)
 		pow = (nor->flags & SNOR_F_HAS_4BIT_BP) ? GENMASK(3, 0) : GENMASK(2, 0);
-	} else {
-		min_prot_len = spi_nor_get_min_prot_length_sr(nor);
+	else
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
-	}
 
 	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top);
 	if (ret)
@@ -281,7 +279,7 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
  */
 static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 {
-	u64 min_prot_len;
+	u64 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 	int ret;
 	u8 status_old[1], status_new[1];
 	loff_t ofs_old, ofs_new;
@@ -329,14 +327,11 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	else
 		lock_len = ofs;
 
-	if (lock_len == 0) {
+	if (lock_len == 0)
 		pow = 0; /* fully unlocked */
-	} else {
-		min_prot_len = spi_nor_get_min_prot_length_sr(nor);
+	else
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
 
-	}
-
 	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top);
 	if (ret)
 		return ret;

-- 
2.51.1

[PATCH v2 16/27] mtd: spi-nor: Create a local SR cache

[Miquel Raynal]

In order to be able to generate debugfs output without having to
actually reach the flash, create a SPI NOR local cache of the status
registers. What matters in our case are all the bits related to sector
locking. As such, in order to make it clear that this cache is not
intended to be used anywhere else, we zero the irrelevant bits.

The cache is initialized once during the early init, and then maintained
every time the write protection scheme is updated.

Suggested-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/core.c  |  6 +++++-
 drivers/mtd/spi-nor/core.h  |  1 +
 drivers/mtd/spi-nor/swp.c   | 35 +++++++++++++++++++++++++++++++++--
 include/linux/mtd/spi-nor.h |  2 ++
 4 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 97da30d9f6c1..ca497ea2228c 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3328,8 +3328,12 @@ static int spi_nor_init(struct spi_nor *nor)
 	 */
 	if (IS_ENABLED(CONFIG_MTD_SPI_NOR_SWP_DISABLE) ||
 	    (IS_ENABLED(CONFIG_MTD_SPI_NOR_SWP_DISABLE_ON_VOLATILE) &&
-	     nor->flags & SNOR_F_SWP_IS_VOLATILE))
+	     nor->flags & SNOR_F_SWP_IS_VOLATILE)) {
 		spi_nor_try_unlock_all(nor);
+	} else {
+		/* In the other cases, make sure the debugfs SR cache is up to date */
+		spi_nor_cache_sr_lock_bits(nor, NULL);
+	}
 
 	if (nor->addr_nbytes == 4 &&
 	    nor->read_proto != SNOR_PROTO_8_8_8_DTR &&
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 3dc9ba3bc6da..091eb934abe4 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -674,6 +674,7 @@ int spi_nor_post_bfpt_fixups(struct spi_nor *nor,
 
 void spi_nor_init_default_locking_ops(struct spi_nor *nor);
 void spi_nor_try_unlock_all(struct spi_nor *nor);
+void spi_nor_cache_sr_lock_bits(struct spi_nor *nor, u8 *sr);
 void spi_nor_set_mtd_locking_ops(struct spi_nor *nor);
 void spi_nor_set_mtd_otp_ops(struct spi_nor *nor);
 
diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index c3dbc8832025..7a6c2b8ef921 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -160,6 +160,25 @@ static int spi_nor_build_sr(struct spi_nor *nor, const u8 *old_sr, u8 *new_sr,
 	return 0;
 }
 
+/*
+ * Keep a local cache containing all lock-related bits for debugfs use only.
+ * This way, debugfs never needs to access the flash directly.
+ */
+void spi_nor_cache_sr_lock_bits(struct spi_nor *nor, u8 *sr)
+{
+	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
+	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
+
+	if (!sr) {
+		if (spi_nor_read_sr(nor, nor->bouncebuf))
+			return;
+
+		sr = nor->bouncebuf;
+	}
+
+	nor->dfs_sr_cache[0] = sr[0] & (bp_mask | tb_mask | SR_SRWD);
+}
+
 /*
  * Lock a region of the flash. Compatible with ST Micro and similar flash.
  * Supports the block protection bits BP{0,1,2}/BP{0,1,2,3} in the status
@@ -269,7 +288,13 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	    (ofs_old < ofs_new || (ofs_new + len_new) < (ofs_old + len_old)))
 		return -EINVAL;
 
-	return spi_nor_write_sr_and_check(nor, status_new[0]);
+	ret = spi_nor_write_sr_and_check(nor, status_new[0]);
+	if (ret)
+		return ret;
+
+	spi_nor_cache_sr_lock_bits(nor, status_new);
+
+	return 0;
 }
 
 /*
@@ -351,7 +376,13 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	    (ofs_new < ofs_old || (ofs_old + len_old) < (ofs_new + len_new)))
 		return -EINVAL;
 
-	return spi_nor_write_sr_and_check(nor, status_new[0]);
+	ret = spi_nor_write_sr_and_check(nor, status_new[0]);
+	if (ret)
+		return ret;
+
+	spi_nor_cache_sr_lock_bits(nor, status_new);
+
+	return 0;
 }
 
 /*
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 90a0cf583512..9ad77f9e76c2 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -371,6 +371,7 @@ struct spi_nor_flash_parameter;
  * @reg_proto:		the SPI protocol for read_reg/write_reg/erase operations
  * @sfdp:		the SFDP data of the flash
  * @debugfs_root:	pointer to the debugfs directory
+ * @dfs_sr_cache:	Status Register cached value for debugfs use only
  * @controller_ops:	SPI NOR controller driver specific operations.
  * @params:		[FLASH-SPECIFIC] SPI NOR flash parameters and settings.
  *                      The structure includes legacy flash parameters and
@@ -409,6 +410,7 @@ struct spi_nor {
 	enum spi_nor_cmd_ext	cmd_ext_type;
 	struct sfdp		*sfdp;
 	struct dentry		*debugfs_root;
+	u8			dfs_sr_cache[2];
 
 	const struct spi_nor_controller_ops *controller_ops;
 

-- 
2.51.1

[PATCH v2 17/27] mtd: spi-nor: debugfs: Add locking support

[Miquel Raynal]

The ioctl output may be counter intuitive in some cases. Asking for a
"locked status" over a region that is only partially locked will return
"unlocked" whereas in practice maybe the biggest part is actually
locked.

Knowing what is the real software locking state through debugfs would be
very convenient for development/debugging purposes, hence this proposal
for adding an extra block at the end of the file: a "locked sectors"
array which lists every section, if it is locked or not, showing both
the address ranges and the sizes in numbers of blocks.

Here is an example of output, what is after the "sector map" is new.

$ cat /sys/kernel/debug/spi-nor/spi0.0/params
name		(null)
id		ef a0 20 00 00 00
size		64.0 MiB
write size	1
page size	256
address nbytes	4
flags		HAS_SR_TB | 4B_OPCODES | HAS_4BAIT | HAS_LOCK | HAS_16BIT_SR | HAS_SR_TB_BIT6 | HAS_4BIT_BP | SOFT_RESET | NO_WP

opcodes
 read		0xec
  dummy cycles	6
 erase		0xdc
 program	0x34
 8D extension	none

protocols
 read		1S-4S-4S
 write		1S-1S-4S
 register	1S-1S-1S

erase commands
 21 (4.00 KiB) [1]
 dc (64.0 KiB) [3]
 c7 (64.0 MiB)

sector map
 region (in hex)   | erase mask | overlaid
 ------------------+------------+---------
 00000000-03ffffff |     [   3] | no

locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03ffffff | unlocked | 1024

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Here are below more examples of output with various situations. The full
output of the "params" content has been manually removed to only show
what has been added and how it behaves.

$ flash_lock -l /dev/mtd0 0x3f00000 16
$ cat /sys/kernel/debug/spi-nor/spi0.0/params
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03efffff | unlocked | 1008
 03f00000-03ffffff |   locked | 16
$
$ flash_lock -u /dev/mtd0 0x3f00000 8
$ cat /sys/kernel/debug/spi-nor/spi0.0/params
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03f7ffff | unlocked | 1016
 03f80000-03ffffff |   locked | 8
$
$ flash_lock -u /dev/mtd0
$ cat /sys/kernel/debug/spi-nor/spi0.0/params
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03ffffff | unlocked | 1024
$
$ flash_lock -l /dev/mtd0
$ cat /sys/kernel/debug/spi-nor/spi0.0/params
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03ffffff |   locked | 1024
$
$ flash_lock -u /dev/mtd0 0x20000 1022
$ cat /sys/kernel/debug/spi-nor/spi0.0/params
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff |   locked | 2
 00020000-03ffffff | unlocked | 1022
---
 drivers/mtd/spi-nor/core.h    |  4 ++++
 drivers/mtd/spi-nor/debugfs.c | 22 ++++++++++++++++++++++
 drivers/mtd/spi-nor/swp.c     | 11 +++++++----
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 091eb934abe4..99ed6c54b90f 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -707,6 +707,10 @@ static inline bool spi_nor_needs_sfdp(const struct spi_nor *nor)
 	return !nor->info->size;
 }
 
+u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor);
+void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_t *ofs, u64 *len);
+bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, const u8 *sr);
+
 #ifdef CONFIG_DEBUG_FS
 void spi_nor_debugfs_register(struct spi_nor *nor);
 void spi_nor_debugfs_shutdown(void);
diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index d0191eb9f879..821fbc9587dc 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -77,10 +77,12 @@ static void spi_nor_print_flags(struct seq_file *s, unsigned long flags,
 static int spi_nor_params_show(struct seq_file *s, void *data)
 {
 	struct spi_nor *nor = s->private;
+	unsigned int min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 	struct spi_nor_flash_parameter *params = nor->params;
 	struct spi_nor_erase_map *erase_map = &params->erase_map;
 	struct spi_nor_erase_region *region = erase_map->regions;
 	const struct flash_info *info = nor->info;
+	loff_t lock_start, lock_length;
 	char buf[16], *str;
 	unsigned int i;
 
@@ -159,6 +161,26 @@ static int spi_nor_params_show(struct seq_file *s, void *data)
 			   region[i].overlaid ? "yes" : "no");
 	}
 
+	seq_puts(s, "\nlocked sectors\n");
+	seq_puts(s, " region (in hex)   | status   | #blocks\n");
+	seq_puts(s, " ------------------+----------+--------\n");
+
+	spi_nor_get_locked_range_sr(nor, nor->dfs_sr_cache, &lock_start, &lock_length);
+	if (!lock_length || lock_length == params->size) {
+		seq_printf(s, " %08llx-%08llx | %s | %llu\n", 0ULL, params->size - 1,
+			   lock_length ? "  locked" : "unlocked", params->size / min_prot_len);
+	} else if (!lock_start) {
+		seq_printf(s, " %08llx-%08llx | %s | %llu\n", 0ULL, lock_length - 1,
+			   "  locked", lock_length / min_prot_len);
+		seq_printf(s, " %08llx-%08llx | %s | %llu\n", lock_length, params->size - 1,
+			   "unlocked", (params->size - lock_length) / min_prot_len);
+	} else {
+		seq_printf(s, " %08llx-%08llx | %s | %llu\n", 0ULL, lock_start - 1,
+			   "unlocked", lock_start / min_prot_len);
+		seq_printf(s, " %08llx-%08llx | %s | %llu\n", lock_start, params->size - 1,
+			   "  locked", lock_length / min_prot_len);
+	}
+
 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(spi_nor_params);
diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 7a6c2b8ef921..8de8459e8e90 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -32,7 +32,7 @@ static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor)
 		return SR_TB_BIT5;
 }
 
-static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
+u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
 {
 	unsigned int bp_slots, bp_slots_needed;
 	/*
@@ -53,8 +53,8 @@ static u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
 		return sector_size;
 }
 
-static void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_t *ofs,
-					u64 *len)
+void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_t *ofs,
+				 u64 *len)
 {
 	u64 min_prot_len;
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
@@ -112,7 +112,7 @@ static bool spi_nor_check_lock_status_sr(struct spi_nor *nor, loff_t ofs,
 		return (ofs >= lock_offs_max) || (offs_max <= lock_offs);
 }
 
-static bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, const u8 *sr)
+bool spi_nor_is_locked_sr(struct spi_nor *nor, loff_t ofs, u64 len, const u8 *sr)
 {
 	return spi_nor_check_lock_status_sr(nor, ofs, len, sr, true);
 }
@@ -410,6 +410,9 @@ static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, u64 len)
  * -is_locked(): Checks if the region is *fully* locked, returns false otherwise.
  *               This feeback may be misleading because users may get an "unlocked"
  *               status even though a subpart of the region is effectively locked.
+ *
+ * If in doubt during development, check-out the debugfs output which tries to
+ * be more user friendly.
  */
 static const struct spi_nor_locking_ops spi_nor_sr_locking_ops = {
 	.lock = spi_nor_sr_lock,

-- 
2.51.1

[PATCH v2 18/27] mtd: spi-nor: debugfs: Add a locked sectors map

[Miquel Raynal]

In order to get a very clear view of the sectors being locked, besides
the `params` output giving the ranges, we may want to see a proper map
of the sectors and for each of them, their status. Depending on the use
case, this map may be easier to parse by humans and gives a more acurate
feeling of the situation. At least myself, for the few locking-related
developments I recently went through, I found it very useful to get a
clearer mental model of what was locked/unlocked.

Here is an example of output:

$ cat /sys/kernel/debug/spi-nor/spi0.0/locked-sectors-map
Locked sectors map (x: locked, .: unlocked, unit: 64kiB)
 0x00000000 (#    0): ................ ................ ................ ................
 0x00400000 (#   64): ................ ................ ................ ................
 0x00800000 (#  128): ................ ................ ................ ................
 0x00c00000 (#  192): ................ ................ ................ ................
 0x01000000 (#  256): ................ ................ ................ ................
 0x01400000 (#  320): ................ ................ ................ ................
 0x01800000 (#  384): ................ ................ ................ ................
 0x01c00000 (#  448): ................ ................ ................ ................
 0x02000000 (#  512): ................ ................ ................ ................
 0x02400000 (#  576): ................ ................ ................ ................
 0x02800000 (#  640): ................ ................ ................ ................
 0x02c00000 (#  704): ................ ................ ................ ................
 0x03000000 (#  768): ................ ................ ................ ................
 0x03400000 (#  832): ................ ................ ................ ................
 0x03800000 (#  896): ................ ................ ................ ................
 0x03c00000 (#  960): ................ ................ ................ ..............xx

The output is wrapped at 64 sectors, spaces every 16 sectors are
improving the readability, every line starts by the first sector
offset (hex) and number (decimal).

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/debugfs.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index 821fbc9587dc..c290bfe20f73 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -185,6 +185,40 @@ static int spi_nor_params_show(struct seq_file *s, void *data)
 }
 DEFINE_SHOW_ATTRIBUTE(spi_nor_params);
 
+static int spi_nor_locked_sectors_map_show(struct seq_file *s, void *data)
+{
+	struct spi_nor *nor = s->private;
+	struct spi_nor_flash_parameter *params = nor->params;
+	unsigned int min_prot_len = spi_nor_get_min_prot_length_sr(nor);
+	unsigned int offset = 0, sector = 0;
+	bool locked;
+	int i;
+
+	seq_printf(s, "Locked sectors map (x: locked, .: unlocked, unit: %dkiB)\n",
+		   min_prot_len / 1024);
+	while (offset < params->size) {
+		seq_printf(s, " 0x%08x (#%5d): ", offset, sector);
+		for (i = 0; i < 64 && offset < params->size; i++) {
+			locked = spi_nor_is_locked_sr(nor, offset, min_prot_len,
+						      nor->dfs_sr_cache);
+			if (locked)
+				seq_puts(s, "x");
+			else
+				seq_puts(s, ".");
+
+			if (((i + 1) % 16) == 0)
+				seq_puts(s, " ");
+
+			offset += min_prot_len;
+			sector++;
+		}
+		seq_puts(s, "\n");
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(spi_nor_locked_sectors_map);
+
 static void spi_nor_print_read_cmd(struct seq_file *s, u32 cap,
 				   struct spi_nor_read_command *cmd)
 {
@@ -270,6 +304,7 @@ void spi_nor_debugfs_register(struct spi_nor *nor)
 	debugfs_create_file("params", 0444, d, nor, &spi_nor_params_fops);
 	debugfs_create_file("capabilities", 0444, d, nor,
 			    &spi_nor_capabilities_fops);
+	debugfs_create_file("locked-sectors-map", 0444, d, nor, &spi_nor_locked_sectors_map_fops);
 }
 
 void spi_nor_debugfs_shutdown(void)

-- 
2.51.1

[PATCH v2 19/27] mtd: spi-nor: Add steps for testing locking support

[Miquel Raynal]

As recently raised on the mailing list, it may be useful to propose a
list of steps to go through in order to proove the devices have been
described correctly, especially since all the block protection
information is not stored in any kind of table and is instead filled
manually by developpers.

Use the debugfs output to ease the comparison between expectations and
reality.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 Documentation/driver-api/mtd/spi-nor.rst | 128 +++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/Documentation/driver-api/mtd/spi-nor.rst b/Documentation/driver-api/mtd/spi-nor.rst
index 148fa4288760..4755eb75fe5e 100644
--- a/Documentation/driver-api/mtd/spi-nor.rst
+++ b/Documentation/driver-api/mtd/spi-nor.rst
@@ -203,3 +203,131 @@ section, after the ``---`` marker.
     mtd.writesize = 1
     mtd.oobsize = 0
     regions = 0
+
+5) If your flash supports locking, please go through the following test
+   procedure to make sure it correctly behaves. The below example
+   expects the typical situation where eraseblocks and lock sectors have
+   the same size. In case you enabled MTD_SPI_NOR_USE_4K_SECTORS, you
+   must adapt `bs` accordingly.
+
+   Warning: These tests may hard lock your device! Make sure:
+   - The device is not hard locked already (#WP strapped to low and
+     SR_SRWD bit set)
+   - If you have a WPn pin, you may want to set `no-wp` in your DT for
+     the time of the test, to only make use of software protection.
+     Otherwise, clearing the locking state depends on the WPn
+     signal and if it is tied to low, the flash will be permanently
+     locked.
+
+   Test full chip locking and make sure expectations, the MEMISLOCKED
+   ioctl output, the debugfs output and experimental results are all
+   aligned::
+
+    root@1:~# alias show_sectors='grep -A4 "locked sectors" /sys/kernel/debug/spi-nor/spi0.0/params'
+    root@1:~# flash_lock -u /dev/mtd0
+    root@1:~# flash_lock -i /dev/mtd0
+    Device: /dev/mtd0
+    Start: 0
+    Len: 0x4000000
+    Lock status: unlocked
+    Return code: 0
+    root@1:~# mtd_debug erase /dev/mtd0 0 2097152
+    Erased 2097152 bytes from address 0x00000000 in flash
+    root@1:~# mtd_debug write /dev/mtd0 0 2097152 spi_test
+    Copied 2097152 bytes from spi_test to address 0x00000000 in flash
+    root@1:~# mtd_debug read /dev/mtd0 0 2097152 spi_read
+    Copied 2097152 bytes from address 0x00000000 in flash to spi_read
+    root@1:~# sha256sum spi*
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_read
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_test
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-03ffffff | unlocked | 1024
+
+    root@1:~# flash_lock -l /dev/mtd0
+    root@1:~# flash_lock -i /dev/mtd0
+    Device: /dev/mtd0
+    Start: 0
+    Len: 0x4000000
+    Lock status: locked
+    Return code: 1
+    root@1:~# mtd_debug erase /dev/mtd0 0 2097152
+    Erased 2097152 bytes from address 0x00000000 in flash
+    root@1:~# mtd_debug read /dev/mtd0 0 2097152 spi_read
+    Copied 2097152 bytes from address 0x00000000 in flash to spi_read
+    root@1:~# sha256sum spi*
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_read
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_test
+    root@1:~# dd if=/dev/urandom of=./spi_test2 bs=1M count=2
+    2+0 records in
+    2+0 records out
+    root@1:~# mtd_debug write /dev/mtd0 0 2097152 spi_test2
+    Copied 2097152 bytes from spi_test to address 0x00000000 in flash
+    root@1:~# mtd_debug read /dev/mtd0 0 2097152 spi_read2
+    Copied 2097152 bytes from address 0x00000000 in flash to spi_read
+    root@1:~# sha256sum spi*
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_read
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_read2
+    c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8  spi_test
+    bea9334df51c620440f86751cba0799214a016329f1736f9456d40cf40efdc88  spi_test2
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-03ffffff |   locked | 1024
+
+   Once we trust the debugfs output we can use it to test various
+   situations. Check top locking/unlocking (end of the device)::
+
+    root@1:~# bs=$(cat /sys/class/mtd/mtd0/erasesize)
+    root@1:~# size=$(cat /sys/class/mtd/mtd0/size)
+
+    root@1:~# flash_lock -u /dev/mtd0
+    root@1:~# flash_lock -l /dev/mtd0 $(($size - (2 * $bs))) 2 # last two
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-03fdffff | unlocked | 1022
+     03fe0000-03ffffff |   locked | 2
+    root@1:~# flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # last one
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-03feffff | unlocked | 1023
+     03ff0000-03ffffff |   locked | 1
+
+   If the flash features 4 block protection bits (BP), we can protect
+   more than 4MB (typically 128 64kiB-blocks or more), with a finer
+   grain than locking the entire device::
+
+    root@1:~# flash_lock -u /dev/mtd0
+    root@1:~# flash_lock -l /dev/mtd0 $(($size - (2**7 * $bs))) $((2**7))
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-037fffff | unlocked | 896
+     03800000-03ffffff |   locked | 128
+
+   If the flash features a Top/Bottom (TB) bit, we can protect the
+   beginning of the flash::
+
+    root@1:~# flash_lock -u /dev/mtd0
+    root@1:~# flash_lock -l /dev/mtd0 0 2 # first two
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-0001ffff |   locked | 2
+     00020000-03ffffff | unlocked | 1022
+    root@1:~# flash_lock -u /dev/mtd0 $bs 1 # first one
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-0000ffff |   locked | 1
+     00010000-03ffffff | unlocked | 1023

-- 
2.51.1

[PATCH v2 20/27] mtd: spi-nor: swp: Add support for the complement feature

[Miquel Raynal]

The current locking implementation allows to select a power of two
number of blocks, which is going to be the protected amount, as well as
telling whether this is the data at the top (end of the device) or the
bottom (beginning of the device). This means at most we can cover half
of the device or the entire device, but nothing in between.

The complement feature allows a much finer grain of configuration, by
allowing to invert what is considered locked and unlocked.

Add support for this feature. The only known position for the CMP bit is
bit 6 of the configuration register.

The locking and unlocking logics are kept unchanged if the CMP bit is
unavailable. Otherwise, once the regular logic has been applied, we
check if we already found an optimal configuration. If not, we try with
the CMP bit set. If the coverage is closer to the request, we use it.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mtd/spi-nor/core.c    |   3 +
 drivers/mtd/spi-nor/core.h    |   4 +
 drivers/mtd/spi-nor/debugfs.c |   1 +
 drivers/mtd/spi-nor/swp.c     | 196 +++++++++++++++++++++++++++++++++++-------
 include/linux/mtd/spi-nor.h   |   1 +
 5 files changed, 173 insertions(+), 32 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index ca497ea2228c..93fd32d54c12 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2974,6 +2974,9 @@ static void spi_nor_init_flags(struct spi_nor *nor)
 			nor->flags |= SNOR_F_HAS_SR_BP3_BIT6;
 	}
 
+	if (flags & SPI_NOR_HAS_CMP)
+		nor->flags |= SNOR_F_HAS_SR2_CMP_BIT6;
+
 	if (flags & SPI_NOR_RWW && nor->params->n_banks > 1 &&
 	    !nor->controller_ops)
 		nor->flags |= SNOR_F_RWW;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 99ed6c54b90f..333786913ff1 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -141,6 +141,7 @@ enum spi_nor_option_flags {
 	SNOR_F_ECC		= BIT(15),
 	SNOR_F_NO_WP		= BIT(16),
 	SNOR_F_SWAP16		= BIT(17),
+	SNOR_F_HAS_SR2_CMP_BIT6	= BIT(18),
 };
 
 struct spi_nor_read_command {
@@ -483,6 +484,8 @@ struct spi_nor_id {
  *   SPI_NOR_NO_ERASE:        no erase command needed.
  *   SPI_NOR_QUAD_PP:         flash supports Quad Input Page Program.
  *   SPI_NOR_RWW:             flash supports reads while write.
+ *   SPI_NOR_HAS_CMP:         flash SR2 has complement (CMP) protect bit. Must
+ *                            be used with SPI_NOR_HAS_LOCK.
  *
  * @no_sfdp_flags:  flags that indicate support that can be discovered via SFDP.
  *                  Used when SFDP tables are not defined in the flash. These
@@ -531,6 +534,7 @@ struct flash_info {
 #define SPI_NOR_NO_ERASE		BIT(6)
 #define SPI_NOR_QUAD_PP			BIT(8)
 #define SPI_NOR_RWW			BIT(9)
+#define SPI_NOR_HAS_CMP			BIT(10)
 
 	u8 no_sfdp_flags;
 #define SPI_NOR_SKIP_SFDP		BIT(0)
diff --git a/drivers/mtd/spi-nor/debugfs.c b/drivers/mtd/spi-nor/debugfs.c
index c290bfe20f73..fb6240dbbfc6 100644
--- a/drivers/mtd/spi-nor/debugfs.c
+++ b/drivers/mtd/spi-nor/debugfs.c
@@ -29,6 +29,7 @@ static const char *const snor_f_names[] = {
 	SNOR_F_NAME(ECC),
 	SNOR_F_NAME(NO_WP),
 	SNOR_F_NAME(SWAP16),
+	SNOR_F_NAME(HAS_SR2_CMP_BIT6),
 };
 #undef SNOR_F_NAME
 
diff --git a/drivers/mtd/spi-nor/swp.c b/drivers/mtd/spi-nor/swp.c
index 8de8459e8e90..ac405b1daf96 100644
--- a/drivers/mtd/spi-nor/swp.c
+++ b/drivers/mtd/spi-nor/swp.c
@@ -32,6 +32,15 @@ static u8 spi_nor_get_sr_tb_mask(struct spi_nor *nor)
 		return SR_TB_BIT5;
 }
 
+static u8 spi_nor_get_sr_cmp_mask(struct spi_nor *nor)
+{
+	if (!(nor->flags & SNOR_F_NO_READ_CR) &&
+	    nor->flags & SNOR_F_HAS_SR2_CMP_BIT6)
+		return SR2_CMP_BIT6;
+	else
+		return 0;
+}
+
 u64 spi_nor_get_min_prot_length_sr(struct spi_nor *nor)
 {
 	unsigned int bp_slots, bp_slots_needed;
@@ -59,8 +68,10 @@ void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_t *ofs,
 	u64 min_prot_len;
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
+	u8 cmp_mask = spi_nor_get_sr_tb_mask(nor);
 	u8 bp, val = sr[0] & bp_mask;
 	bool tb = (nor->flags & SNOR_F_HAS_SR_TB) ? sr[0] & tb_mask : 0;
+	bool cmp = sr[1] & cmp_mask;
 
 	if (nor->flags & SNOR_F_HAS_SR_BP3_BIT6 && val & SR_BP3_BIT6)
 		val = (val & ~SR_BP3_BIT6) | SR_BP3;
@@ -68,22 +79,37 @@ void spi_nor_get_locked_range_sr(struct spi_nor *nor, const u8 *sr, loff_t *ofs,
 	bp = val >> SR_BP_SHIFT;
 
 	if (!bp) {
-		/* No protection */
-		*ofs = 0;
-		*len = 0;
-		return;
+		if (!cmp) {
+			/* No protection */
+			*ofs = 0;
+			*len = 0;
+			return;
+		} else {
+			/* Full protection */
+			*ofs = 0;
+			*len = nor->params->size;
+		}
 	}
 
 	min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 	*len = min_prot_len << (bp - 1);
-
 	if (*len > nor->params->size)
 		*len = nor->params->size;
 
-	if (tb)
-		*ofs = 0;
-	else
-		*ofs = nor->params->size - *len;
+	if (cmp)
+		*len = nor->params->size - *len;
+
+	if (!cmp) {
+		if (tb)
+			*ofs = 0;
+		else
+			*ofs = nor->params->size - *len;
+	} else {
+		if (tb)
+			*ofs = nor->params->size - *len;
+		else
+			*ofs = 0;
+	}
 }
 
 /*
@@ -140,13 +166,15 @@ static int spi_nor_sr_set_bp_mask(struct spi_nor *nor, u8 *sr, u8 pow)
 }
 
 static int spi_nor_build_sr(struct spi_nor *nor, const u8 *old_sr, u8 *new_sr,
-			    u8 pow, bool use_top)
+			    u8 pow, bool use_top, bool cmp)
 {
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
+	u8 cmp_mask = spi_nor_get_sr_cmp_mask(nor);
 	int ret;
 
 	new_sr[0] = old_sr[0] & ~bp_mask & ~tb_mask;
+	new_sr[1] = old_sr[1] & ~cmp_mask;
 
 	/* Build BP field */
 	ret = spi_nor_sr_set_bp_mask(nor, &new_sr[0], pow);
@@ -154,9 +182,13 @@ static int spi_nor_build_sr(struct spi_nor *nor, const u8 *old_sr, u8 *new_sr,
 		return ret;
 
 	/* Build TB field */
-	if (!use_top)
+	if ((!cmp && !use_top) || (cmp && use_top))
 		new_sr[0] |= tb_mask;
 
+	/* Build CMP field */
+	if (cmp)
+		new_sr[1] |= cmp_mask;
+
 	return 0;
 }
 
@@ -168,15 +200,22 @@ void spi_nor_cache_sr_lock_bits(struct spi_nor *nor, u8 *sr)
 {
 	u8 bp_mask = spi_nor_get_sr_bp_mask(nor);
 	u8 tb_mask = spi_nor_get_sr_tb_mask(nor);
+	u8 cmp_mask = spi_nor_get_sr_cmp_mask(nor);
 
 	if (!sr) {
 		if (spi_nor_read_sr(nor, nor->bouncebuf))
 			return;
 
+		if (!(nor->flags & SNOR_F_NO_READ_CR)) {
+			if (spi_nor_read_cr(nor, nor->bouncebuf + 1))
+				return;
+		}
+
 		sr = nor->bouncebuf;
 	}
 
 	nor->dfs_sr_cache[0] = sr[0] & (bp_mask | tb_mask | SR_SRWD);
+	nor->dfs_sr_cache[1] = sr[1] & cmp_mask;
 }
 
 /*
@@ -185,10 +224,11 @@ void spi_nor_cache_sr_lock_bits(struct spi_nor *nor, u8 *sr)
  * register
  * (SR). Does not support these features found in newer SR bitfields:
  *   - SEC: sector/block protect - only handle SEC=0 (block protect)
- *   - CMP: complement protect - only support CMP=0 (range is not complemented)
  *
  * Support for the following is provided conditionally for some flash:
  *   - TB: top/bottom protect
+ *   - CMP: complement protect (BP and TP describe the unlocked part, while
+ *          the reminder is locked)
  *
  * Sample table portion for 8MB flash (Winbond w25q64fw):
  *
@@ -215,11 +255,13 @@ void spi_nor_cache_sr_lock_bits(struct spi_nor *nor, u8 *sr)
 static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 {
 	u64 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
-	u8 status_old[1] = {}, status_new[1] = {};
-	loff_t ofs_old, ofs_new;
-	u64 len_old, len_new;
+	u8 status_old[2] = {}, status_new[2] = {}, status_new_cmp[2] = {};
+	u8 *best_status_new = status_new;
+	loff_t ofs_old, ofs_new, ofs_new_cmp;
+	u64 len_old, len_new, len_new_cmp;
 	loff_t lock_len;
-	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
+	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB,
+		can_be_cmp = spi_nor_get_sr_cmp_mask(nor);
 	bool use_top;
 	int ret;
 	u8 pow;
@@ -230,6 +272,14 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 
 	status_old[0] = nor->bouncebuf[0];
 
+	if (!(nor->flags & SNOR_F_NO_READ_CR)) {
+		ret = spi_nor_read_cr(nor, nor->bouncebuf + 1);
+		if (ret)
+			return ret;
+
+		status_old[1] = nor->bouncebuf[1];
+	}
+
 	/* If nothing in our range is unlocked, we don't need to do anything */
 	if (spi_nor_is_locked_sr(nor, ofs, len, status_old))
 		return 0;
@@ -260,24 +310,56 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	else
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
 
-	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top);
+	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top, false);
 	if (ret)
 		return ret;
 
+	/*
+	 * In case the region asked is not fully met, maybe we can try with the
+	 * complement feature
+	 */
+	spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+	if (can_be_cmp && len_new != lock_len) {
+		pow = ilog2(nor->params->size - lock_len) - ilog2(min_prot_len) + 1;
+		ret = spi_nor_build_sr(nor, status_old, status_new_cmp, pow, use_top, true);
+		if (ret)
+			return ret;
+
+		/*
+		 * ilog2() "floors" the result, which means in some cases we may have to
+		 * manually reduce the scope when the complement feature is used.
+		 * The uAPI is to never lock more than what is requested, but less is accepted.
+		 * Make sure we are not covering a too wide range, reduce it otherwise.
+		 */
+		spi_nor_get_locked_range_sr(nor, status_new_cmp, &ofs_new_cmp, &len_new_cmp);
+		if (len_new_cmp > lock_len) {
+			pow++;
+			ret = spi_nor_build_sr(nor, status_old, status_new_cmp, pow, use_top, true);
+			if (ret)
+				return ret;
+		}
+
+		/* Pick the CMP configuration if we cover a closer range */
+		spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+		spi_nor_get_locked_range_sr(nor, status_new_cmp, &ofs_new_cmp, &len_new_cmp);
+		if (len_new_cmp > len_new)
+			best_status_new = status_new_cmp;
+	}
+
 	/*
 	 * Disallow further writes if WP# pin is neither left floating nor
 	 * wrongly tied to GND (that includes internal pull-downs).
 	 * WP# pin hard strapped to GND can be a valid use case.
 	 */
 	if (!(nor->flags & SNOR_F_NO_WP))
-		status_new[0] |= SR_SRWD;
+		best_status_new[0] |= SR_SRWD;
 
 	/* Don't bother if they're the same */
-	if (status_new[0] == status_old[0])
+	if (best_status_new[0] == status_old[0] && best_status_new[1] == status_old[1])
 		return 0;
 
 	spi_nor_get_locked_range_sr(nor, status_old, &ofs_old, &len_old);
-	spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+	spi_nor_get_locked_range_sr(nor, best_status_new, &ofs_new, &len_new);
 
 	/* Don't "lock" with no region! */
 	if (!len_new)
@@ -288,11 +370,11 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, u64 len)
 	    (ofs_old < ofs_new || (ofs_new + len_new) < (ofs_old + len_old)))
 		return -EINVAL;
 
-	ret = spi_nor_write_sr_and_check(nor, status_new[0]);
+	ret = spi_nor_write_sr_cr_and_check(nor, best_status_new);
 	if (ret)
 		return ret;
 
-	spi_nor_cache_sr_lock_bits(nor, status_new);
+	spi_nor_cache_sr_lock_bits(nor, best_status_new);
 
 	return 0;
 }
@@ -306,11 +388,13 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 {
 	u64 min_prot_len = spi_nor_get_min_prot_length_sr(nor);
 	int ret;
-	u8 status_old[1], status_new[1];
-	loff_t ofs_old, ofs_new;
-	u64 len_old, len_new;
+	u8 status_old[2], status_new[2], status_new_cmp[2];
+	u8 *best_status_new = status_new;
+	loff_t ofs_old, ofs_new, ofs_new_cmp;
+	u64 len_old, len_new, len_new_cmp;
 	loff_t lock_len;
-	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB;
+	bool can_be_top = true, can_be_bottom = nor->flags & SNOR_F_HAS_SR_TB,
+		can_be_cmp = spi_nor_get_sr_cmp_mask(nor);
 	bool use_top;
 	u8 pow;
 
@@ -320,6 +404,14 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 
 	status_old[0] = nor->bouncebuf[0];
 
+	if (!(nor->flags & SNOR_F_NO_READ_CR)) {
+		ret = spi_nor_read_cr(nor, nor->bouncebuf + 1);
+		if (ret)
+			return ret;
+
+		status_old[1] = nor->bouncebuf[1];
+	}
+
 	/* If nothing in our range is locked, we don't need to do anything */
 	if (spi_nor_is_unlocked_sr(nor, ofs, len, status_old))
 		return 0;
@@ -357,30 +449,62 @@ static int spi_nor_sr_unlock(struct spi_nor *nor, loff_t ofs, u64 len)
 	else
 		pow = ilog2(lock_len) - ilog2(min_prot_len) + 1;
 
-	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top);
+	ret = spi_nor_build_sr(nor, status_old, status_new, pow, use_top, false);
 	if (ret)
 		return ret;
 
+	/*
+	 * In case the region asked is not fully met, maybe we can try with the
+	 * complement feature
+	 */
+	spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+	if (can_be_cmp && len_new != lock_len) {
+		pow = ilog2(nor->params->size - lock_len) - ilog2(min_prot_len) + 1;
+		ret = spi_nor_build_sr(nor, status_old, status_new_cmp, pow, use_top, true);
+		if (ret)
+			return ret;
+
+		/*
+		 * ilog2() "floors" the result, which means in some cases we may have to
+		 * manually reduce the scope when the complement feature is used.
+		 * The uAPI is to never unlock more than what is requested, but less is accepted.
+		 * Make sure we are not covering a too small range, increase it otherwise.
+		 */
+		spi_nor_get_locked_range_sr(nor, status_new_cmp, &ofs_new_cmp, &len_new_cmp);
+		if (len_new_cmp < lock_len) {
+			pow--;
+			ret = spi_nor_build_sr(nor, status_old, status_new_cmp, pow, use_top, true);
+			if (ret)
+				return ret;
+		}
+
+		/* Pick the CMP configuration if we cover a closer range */
+		spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+		spi_nor_get_locked_range_sr(nor, status_new_cmp, &ofs_new_cmp, &len_new_cmp);
+		if (len_new_cmp > len_new)
+			best_status_new = status_new_cmp;
+	}
+
 	/* Don't protect status register if we're fully unlocked */
 	if (lock_len == 0)
-		status_new[0] &= ~SR_SRWD;
+		best_status_new[0] &= ~SR_SRWD;
 
 	/* Don't bother if they're the same */
-	if (status_new[0] == status_old[0])
+	if (best_status_new[0] == status_old[0] && best_status_new[1] == status_old[1])
 		return 0;
 
 	/* Only modify protection if it will not lock other areas */
 	spi_nor_get_locked_range_sr(nor, status_old, &ofs_old, &len_old);
-	spi_nor_get_locked_range_sr(nor, status_new, &ofs_new, &len_new);
+	spi_nor_get_locked_range_sr(nor, best_status_new, &ofs_new, &len_new);
 	if (len_old && len_new &&
 	    (ofs_new < ofs_old || (ofs_old + len_old) < (ofs_new + len_new)))
 		return -EINVAL;
 
-	ret = spi_nor_write_sr_and_check(nor, status_new[0]);
+	ret = spi_nor_write_sr_cr_and_check(nor, best_status_new);
 	if (ret)
 		return ret;
 
-	spi_nor_cache_sr_lock_bits(nor, status_new);
+	spi_nor_cache_sr_lock_bits(nor, best_status_new);
 
 	return 0;
 }
@@ -400,6 +524,14 @@ static int spi_nor_sr_is_locked(struct spi_nor *nor, loff_t ofs, u64 len)
 	if (ret)
 		return ret;
 
+	if (!(nor->flags & SNOR_F_NO_READ_CR)) {
+		ret = spi_nor_read_cr(nor, nor->bouncebuf + 1);
+		if (ret)
+			return ret;
+	} else {
+		nor->bouncebuf[1] = 0;
+	}
+
 	return spi_nor_is_locked_sr(nor, ofs, len, nor->bouncebuf);
 }
 
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 9ad77f9e76c2..4b92494827b1 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -125,6 +125,7 @@
 #define SR2_LB1			BIT(3)	/* Security Register Lock Bit 1 */
 #define SR2_LB2			BIT(4)	/* Security Register Lock Bit 2 */
 #define SR2_LB3			BIT(5)	/* Security Register Lock Bit 3 */
+#define SR2_CMP_BIT6		BIT(6)
 #define SR2_QUAD_EN_BIT7	BIT(7)
 
 /* Supported SPI protocols */

-- 
2.51.1

[PATCH v2 21/27] mtd: spi-nor: Add steps for testing locking with CMP

[Miquel Raynal]

Extend the test coverage by giving guidelines to verify the CMP bit acts
according to our expectations.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
The instructions listed in this file target people adding support for
new chips, however here are below extra steps that I also ran with the
same W25H512NWxxAM chip. They are here to prove core correctness.

    $ flash_lock -u /dev/mtd0
    $ flash_lock -l /dev/mtd0 0 1008
    $ show_sectors
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03efffff |   locked | 1008
     03f00000-03ffffff | unlocked | 16
    $ flash_lock -l /dev/mtd0 0 1009
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03efffff |   locked | 1008
     03f00000-03ffffff | unlocked | 16
    $ flash_lock -l /dev/mtd0 0 1015
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03efffff |   locked | 1008
     03f00000-03ffffff | unlocked | 16
    $ flash_lock -l /dev/mtd0 0 1016
    $ show_sectors # should cover more
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03f7ffff |   locked | 1016
     03f80000-03ffffff | unlocked | 8
    $ flash_lock -u /dev/mtd0 $((1015 * $bs)) 1
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03f7ffff |   locked | 1016
     03f80000-03ffffff | unlocked | 8
    $ flash_lock -u /dev/mtd0 $((1009 * $bs)) 7
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03f7ffff |   locked | 1016
     03f80000-03ffffff | unlocked | 8
    $ flash_lock -u /dev/mtd0 $((1008 * $bs)) 8
    $ show_sectors # range should reduce down to initial value
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-03efffff |   locked | 1008
     03f00000-03ffffff | unlocked | 16

    [Similar situations, on the other side of the device]

    $ flash_lock -u /dev/mtd0
    $ flash_lock -l /dev/mtd0 $((16 * $bs)) 1008
    $ show_sectors
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-000fffff | unlocked | 16
     00100000-03ffffff |   locked | 1008
    $ flash_lock -l /dev/mtd0 $((15 * $bs)) 1009
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-000fffff | unlocked | 16
     00100000-03ffffff |   locked | 1008
    $ flash_lock -l /dev/mtd0 $((9 * $bs)) 1015
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-000fffff | unlocked | 16
     00100000-03ffffff |   locked | 1008
    $ flash_lock -l /dev/mtd0 $((8 * $bs)) 1016
    $ show_sectors # should cover more
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-0007ffff | unlocked | 8
     00080000-03ffffff |   locked | 1016
    $ flash_lock -u /dev/mtd0 $((8 * $bs)) 1
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-0007ffff | unlocked | 8
     00080000-03ffffff |   locked | 1016
    $ flash_lock -u /dev/mtd0 $((8 * $bs)) 7
    $ show_sectors # should not change
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-0007ffff | unlocked | 8
     00080000-03ffffff |   locked | 1016
    $ flash_lock -u /dev/mtd0 $((8 * $bs)) 8
    $ show_sectors # range should reduce down to initial value
    software locked sectors
     region (in hex)   | status   | #blocks
     ------------------+----------+--------
     00000000-000fffff | unlocked | 16
     00100000-03ffffff |   locked | 1008
---
 Documentation/driver-api/mtd/spi-nor.rst | 36 ++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/Documentation/driver-api/mtd/spi-nor.rst b/Documentation/driver-api/mtd/spi-nor.rst
index 4755eb75fe5e..ec46bba8297a 100644
--- a/Documentation/driver-api/mtd/spi-nor.rst
+++ b/Documentation/driver-api/mtd/spi-nor.rst
@@ -331,3 +331,39 @@ section, after the ``---`` marker.
      ------------------+----------+--------
      00000000-0000ffff |   locked | 1
      00010000-03ffffff | unlocked | 1023
+
+   If the flash features a Complement (CMP) bit, we can protect with
+   more granularity above half of the capacity. Let's lock all but one
+   block, then unlock one more block::
+
+    root@1:~# all_but_one=$((($size / $bs) - 1))
+    root@1:~# flash_lock -u /dev/mtd0
+    root@1:~# flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-0000ffff | unlocked | 1
+     00010000-03ffffff |   locked | 1023
+    root@1:~# flash_lock -u /dev/mtd0 $bs 1 # all but the two first
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-0001ffff | unlocked | 2
+     00020000-03ffffff |   locked | 1022
+    root@1:~# flash_lock -u /dev/mtd0
+    root@1:~# flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-03feffff |   locked | 1023
+     03ff0000-03ffffff | unlocked | 1
+    root@1:~# flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # all but two
+    root@1:~# show_sectors
+    software locked sectors
+     region (in hex)   | status   | #blocks
+     ------------------+----------+--------
+     00000000-03fdffff |   locked | 1022
+     03fe0000-03ffffff | unlocked | 2

-- 
2.51.1

[PATCH v2 22/27] mtd: spi-nor: winbond: Add W25H512NWxxAM CMP locking support

[Miquel Raynal]

This chip has support for the locking complement (CMP) feature. Add
the relevant bit to enable it.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Test run following the freshly written documentation:

$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0000ffff | unlocked | 1
 00010000-03ffffff |   locked | 1023
$ flash_lock -u /dev/mtd0 $bs 1 # all but the two first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff | unlocked | 2
 00020000-03ffffff |   locked | 1022
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03feffff |   locked | 1023
 03ff0000-03ffffff | unlocked | 1
$ flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # all but two
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-03fdffff |   locked | 1022
 03fe0000-03ffffff | unlocked | 2
---
 drivers/mtd/spi-nor/winbond.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index fb855fe44733..7609dcc768f0 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -358,7 +358,8 @@ static const struct flash_info winbond_nor_parts[] = {
 	}, {
 		/* W25H512NWxxAM */
 		.id = SNOR_ID(0xef, 0xa0, 0x20),
-		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 | SPI_NOR_4BIT_BP,
+		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 |
+			 SPI_NOR_4BIT_BP | SPI_NOR_HAS_CMP,
 	}, {
 		/* W25H01NWxxAM */
 		.id = SNOR_ID(0xef, 0xa0, 0x21),

-- 
2.51.1

[PATCH v2 23/27] mtd: spi-nor: winbond: Add W25H01NWxxAM CMP locking support

[Miquel Raynal]

This chip has support for the locking complement (CMP) feature. Add
the relevant bit to enable it.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Test run with W25H01NWxxAM:
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0000ffff | unlocked | 1
 00010000-07ffffff |   locked | 2047
$ flash_lock -u /dev/mtd0 $bs 1 # all but the two first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff | unlocked | 2
 00020000-07ffffff |   locked | 2046
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-07feffff |   locked | 2047
 07ff0000-07ffffff | unlocked | 1
$ flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # all but two
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-07fdffff |   locked | 2046
 07fe0000-07ffffff | unlocked | 2
---
 drivers/mtd/spi-nor/winbond.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 7609dcc768f0..1b9b0e9598ef 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -363,7 +363,8 @@ static const struct flash_info winbond_nor_parts[] = {
 	}, {
 		/* W25H01NWxxAM */
 		.id = SNOR_ID(0xef, 0xa0, 0x21),
-		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 | SPI_NOR_4BIT_BP,
+		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 |
+			 SPI_NOR_4BIT_BP | SPI_NOR_HAS_CMP,
 	}, {
 		/* W25H02NWxxAM */
 		.id = SNOR_ID(0xef, 0xa0, 0x22),

-- 
2.51.1

[PATCH v2 24/27] mtd: spi-nor: winbond: Add W25H02NWxxAM CMP locking support

[Miquel Raynal]

This chip has support for the locking complement (CMP) feature. Add
the relevant bit to enable it.

Unfortunately, this chip also comes with an incorrect BFPT table,
indicating the Control Register cannot be read back. This is wrong,
reading back the register works and has no (observed) side effect. The
datasheet clearly indicates supporting the 35h command and all bits from
the CR are marked readable. QE and CMP bits are inside, and can be
properly read back.

Add a fixup for this, otherwise it would defeat the use of the CMP
feature.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Test run with W25H02NWxxAM:
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0000ffff | unlocked | 1
 00010000-0fffffff |   locked | 4095
$ flash_lock -u /dev/mtd0 $bs 1 # all but the two first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff | unlocked | 2
 00020000-0fffffff |   locked | 4094
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0ffeffff |   locked | 4095
 0fff0000-0fffffff | unlocked | 1
$ flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # all but two
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0ffdffff |   locked | 4094
 0ffe0000-0fffffff | unlocked | 2
---
 drivers/mtd/spi-nor/winbond.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 1b9b0e9598ef..959fd4f46eb5 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -73,6 +73,26 @@ static const struct spi_nor_fixups w25q256_fixups = {
 	.post_bfpt = w25q256_post_bfpt_fixups,
 };
 
+static int
+winbond_rdcr_post_bfpt_fixup(struct spi_nor *nor,
+			     const struct sfdp_parameter_header *bfpt_header,
+			     const struct sfdp_bfpt *bfpt)
+{
+	/*
+	 * W25H02NW, unlike its W25H512NW nor W25H01NW cousins, improperly sets
+	 * the QE BFPT configuration bits, indicating a non readable CR. This is
+	 * both incorrect and impractical, as the chip features a CMP bit for its
+	 * locking scheme that lays in the Control Register, and needs to be read.
+	 */
+	nor->flags &= ~SNOR_F_NO_READ_CR;
+
+	return 0;
+}
+
+static const struct spi_nor_fixups winbond_rdcr_fixup = {
+	.post_bfpt = winbond_rdcr_post_bfpt_fixup,
+};
+
 /**
  * winbond_nor_select_die() - Set active die.
  * @nor:	pointer to 'struct spi_nor'.
@@ -368,7 +388,9 @@ static const struct flash_info winbond_nor_parts[] = {
 	}, {
 		/* W25H02NWxxAM */
 		.id = SNOR_ID(0xef, 0xa0, 0x22),
-		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 | SPI_NOR_4BIT_BP,
+		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 |
+			 SPI_NOR_4BIT_BP | SPI_NOR_HAS_CMP,
+		.fixups = &winbond_rdcr_fixup,
 	},
 };
 

-- 
2.51.1

[PATCH v2 25/27] mtd: spi-nor: winbond: Add W25H01NWxxIQ CMP locking support

[Miquel Raynal]

This chip has support for the locking complement (CMP) feature. Add
the relevant bit to enable it.

Unfortunately, this chip also comes with an incorrect BFPT table,
indicating the Control Register cannot be read back. This is wrong,
reading back the register works and has no (observed) side effect. The
datasheet clearly indicates supporting the 35h command and all bits from
the CR are marked readable. QE and CMP bits are inside, and can be
properly read back.

Add a fixup for this, otherwise it would defeat the use of the CMP
feature.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Test run with W25H01NWxxIQ:
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0000ffff | unlocked | 1
 00010000-07ffffff |   locked | 2047
$ flash_lock -u /dev/mtd0 $bs 1 # all but the two first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff | unlocked | 2
 00020000-07ffffff |   locked | 2046
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-07feffff |   locked | 2047
 07ff0000-07ffffff | unlocked | 1
$ flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # alll but two
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-07fdffff |   locked | 2046
 07fe0000-07ffffff | unlocked | 2
---
 drivers/mtd/spi-nor/winbond.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 959fd4f46eb5..373c0af9daa2 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -366,7 +366,9 @@ static const struct flash_info winbond_nor_parts[] = {
 	}, {
 		/* W25Q01NWxxIQ */
 		.id = SNOR_ID(0xef, 0x60, 0x21),
-		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 | SPI_NOR_4BIT_BP,
+		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 |
+			 SPI_NOR_4BIT_BP | SPI_NOR_HAS_CMP,
+		.fixups = &winbond_rdcr_fixup,
 	}, {
 		/* W25Q01NWxxIM */
 		.id = SNOR_ID(0xef, 0x80, 0x21),

-- 
2.51.1

[PATCH v2 26/27] mtd: spi-nor: winbond: Add W25Q01NWxxIM CMP locking support

[Miquel Raynal]

This chip has support for the locking complement (CMP) feature. Add
the relevant bit to enable it.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Test run with W25Q01NWxxIM:
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0000ffff | unlocked | 1
 00010000-0fffffff |   locked | 4095
$ flash_lock -u /dev/mtd0 $bs 1 # all but the two first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff | unlocked | 2
 00020000-0fffffff |   locked | 4094
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0ffeffff |   locked | 4095
 0fff0000-0fffffff | unlocked | 1
$ flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # all but two
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0ffdffff |   locked | 4094
 0ffe0000-0fffffff | unlocked | 2
---
 drivers/mtd/spi-nor/winbond.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 373c0af9daa2..72053a4505f9 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -372,7 +372,8 @@ static const struct flash_info winbond_nor_parts[] = {
 	}, {
 		/* W25Q01NWxxIM */
 		.id = SNOR_ID(0xef, 0x80, 0x21),
-		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 | SPI_NOR_4BIT_BP,
+		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 |
+			 SPI_NOR_4BIT_BP | SPI_NOR_HAS_CMP,
 	}, {
 		/* W25Q02NWxxIM */
 		.id = SNOR_ID(0xef, 0x80, 0x22),

-- 
2.51.1

[PATCH v2 27/27] mtd: spi-nor: winbond: Add W25Q02NWxxIM CMP locking support

[Miquel Raynal]

This chip has support for the locking complement (CMP) feature. Add
the relevant bit to enable it.

Unfortunately, this chip also comes with an incorrect BFPT table,
indicating the Control Register cannot be read back. This is wrong,
reading back the register works and has no (observed) side effect. The
datasheet clearly indicates supporting the 35h command and all bits from
the CR are marked readable. QE and CMP bits are inside, and can be
properly read back.

Add a fixup for this, otherwise it would defeat the use of the CMP
feature.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
Test run with W25Q02NWxxIM:
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 $bs $all_but_one # all but the first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0000ffff | unlocked | 1
 00010000-0fffffff |   locked | 4095
$ flash_lock -u /dev/mtd0 $bs 1 # all but the two first
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0001ffff | unlocked | 2
 00020000-0fffffff |   locked | 4094
$ flash_lock -u /dev/mtd0
$ flash_lock -l /dev/mtd0 0 $all_but_one # same from the other side
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0ffeffff |   locked | 4095
 0fff0000-0fffffff | unlocked | 1
$ flash_lock -u /dev/mtd0 $(($size - (2 * $bs))) 1 # all but two
$ show_sectors
locked sectors
 region (in hex)   | status   | #blocks
 ------------------+----------+--------
 00000000-0ffdffff |   locked | 4094
 0ffe0000-0fffffff | unlocked | 2
---
 drivers/mtd/spi-nor/winbond.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 72053a4505f9..639d72f48769 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -377,7 +377,9 @@ static const struct flash_info winbond_nor_parts[] = {
 	}, {
 		/* W25Q02NWxxIM */
 		.id = SNOR_ID(0xef, 0x80, 0x22),
-		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 | SPI_NOR_4BIT_BP,
+		.flags = SPI_NOR_HAS_LOCK | SPI_NOR_HAS_TB | SPI_NOR_TB_SR_BIT6 |
+			 SPI_NOR_4BIT_BP | SPI_NOR_HAS_CMP,
+		.fixups = &winbond_rdcr_fixup,
 	}, {
 		/* W25H512NWxxAM */
 		.id = SNOR_ID(0xef, 0xa0, 0x20),

-- 
2.51.1

Re: [PATCH v2 01/27] mtd: spi-nor: Drop duplicate Kconfig dependency

[Michael Walle]

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On Thu Jan 8, 2026 at 5:57 PM CET, Miquel Raynal wrote:
> I do not think the MTD dependency is needed twice. This is likely a
> duplicate coming from a former rebase when the spi-nor core got cleaned
> up a while ago. Remove the extra line.
>
> Fixes: b35b9a10362d ("mtd: spi-nor: Move m25p80 code in spi-nor.c")
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Reviewed-by: Michael Walle <mwalle@kernel.org>

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Re: [PATCH v2 03/27] mtd: spi-nor: swp: Improve locking user experience

[Michael Walle]

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On Thu Jan 8, 2026 at 5:57 PM CET, Miquel Raynal wrote:
> In the case of the first block being locked (or the few first blocks),
> if the user want to fully unlock the device it has two possibilities:
> - either it asks to unlock the entire device, and this works;
> - or it asks to unlock just the block(s) that are currently locked,
>   which fails.
>
> It fails because the conditions "can_be_top" and "can_be_bottom" are
> true. Indeed, in this case, we unlock everything, so the TB bit does not
> matter. However in the current implementation, use_top would be true (as
> this is the favourite option) and lock_len, which in practice should be
> reduced down to 0, is set to "nor->params->size - (ofs + len)" which is
> a positive number. This is wrong.
>
> An easy way is to simply add an extra condition. In the unlock() path,
> if we can achieve the same result from both sides, it means we unlock
> everything and lock_len must simply be 0. A comment is added to clarify
> that logic.
>
> Fixes: 3dd8012a8eeb ("mtd: spi-nor: add TB (Top/Bottom) protect support")
> Cc: stable@kernel.org
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Reviewed-by: Michael Walle <mwalle@kernel.org>

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