[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 at 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