diff options
| author | NeilBrown <neil@brown.name> | 2018-04-21 01:54:40 +0300 |
|---|---|---|
| committer | Boris Brezillon <boris.brezillon@bootlin.com> | 2018-04-21 11:05:23 +0300 |
| commit | f134fbbb4ff813dd227c9ce40b5c0b2078a77b07 (patch) | |
| tree | 610eab8a466e1c8a507d39505c982111f5181772 /include/linux/mtd | |
| parent | ce5013ff3bec05cf2a8a05c75fcd520d9914d92b (diff) | |
| download | linux-f134fbbb4ff813dd227c9ce40b5c0b2078a77b07.tar.xz | |
mtd: spi-nor: clear Winbond Extended Address Reg on switch to 3-byte addressing.
Winbond spi-nor flash 32MB and larger have an 'Extended Address
Register' as one option for addressing beyond 16MB (Macronix
has the same concept, Spansion has EXTADD bits in the Bank Address
Register).
According to section
8.2.7 Write Extended Address Register (C5h)
of the Winbond W25Q256FV data sheet (256M-BIT SPI flash)
The Extended Address Register is only effective when the device is
in the 3-Byte Address Mode. When the device operates in the 4-Byte
Address Mode (ADS=1), any command with address input of A31-A24
will replace the Extended Address Register values. It is
recommended to check and update the Extended Address Register if
necessary when the device is switched from 4-Byte to 3-Byte Address
Mode.
So the documentation suggests clearing the EAR after switching to
3-byte mode. Experimentation shows that the EAR is *always* one after
the switch to 3-byte mode, so clearing the EAR is mandatory at
shutdown for a subsequent 3-byte-addressed reboot to work.
Note that some SOCs (e.g. MT7621) do not assert a reset line at normal
reboot, so we cannot rely on hardware reset. The MT7621 does assert a
reset line at watchdog-reset.
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Diffstat (limited to 'include/linux/mtd')
| -rw-r--r-- | include/linux/mtd/spi-nor.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h index de36969eb359..e60da0d34cc1 100644 --- a/include/linux/mtd/spi-nor.h +++ b/include/linux/mtd/spi-nor.h @@ -62,6 +62,8 @@ #define SPINOR_OP_RDCR 0x35 /* Read configuration register */ #define SPINOR_OP_RDFSR 0x70 /* Read flag status register */ #define SPINOR_OP_CLFSR 0x50 /* Clear flag status register */ +#define SPINOR_OP_RDEAR 0xc8 /* Read Extended Address Register */ +#define SPINOR_OP_WREAR 0xc5 /* Write Extended Address Register */ /* 4-byte address opcodes - used on Spansion and some Macronix flashes. */ #define SPINOR_OP_READ_4B 0x13 /* Read data bytes (low frequency) */ |