Am 2020-11-24 20:09, schrieb [email protected]:
On 10/3/20 6:32 PM, Michael Walle wrote:
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This is considered bad for the following reasons:
(1) We only support the block protection with BPn bits for write
protection. Not all Atmel parts support this.
(2) Newly added flash chip will automatically inherit the "has
locking" support and thus needs to explicitly tested. Better
be opt-in instead of opt-out.
(3) There are already supported flashes which doesn't support
the locking scheme. So I assume this wasn't properly tested
before adding that chip; which enforces my previous argument
that locking support should be an opt-in.
Remove the global flag and add individual flags to all flashes which
supports BP locking. In particular the following flashes don't support
the BP scheme:
- AT26F004
- AT25SL321
- AT45DB081D
Please note, that some flashes which are marked as SPI_NOR_HAS_LOCK
just
support Global Protection, i.e. not our supported block protection
locking scheme. This is to keep backwards compatibility with the
current "unlock all at boot" mechanism. In particular the following
flashes doesn't have BP bits:
- AT25DF041A
- AT25DF321
- AT25DF321A
- AT25DF641
- AT26DF081A
- AT26DF161A
- AT26DF321
Signed-off-by: Michael Walle <[email protected]>
Reviewed-by: Tudor Ambarus <[email protected]>
---
changes since v4:
- none
changes since v3/v2/v1:
- there was no such version because this patch was bundled with
another
patch
changes since RFC:
- mention the flashes which just support the "Global Unprotect" in
the
commit message
drivers/mtd/spi-nor/atmel.c | 28 +++++++++-------------------
1 file changed, 9 insertions(+), 19 deletions(-)
diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
index 3f5f21a473a6..49d392c6c8bc 100644
--- a/drivers/mtd/spi-nor/atmel.c
+++ b/drivers/mtd/spi-nor/atmel.c
@@ -10,37 +10,27 @@
static const struct flash_info atmel_parts[] = {
/* Atmel -- some are (confusingly) marketed as "DataFlash" */
- { "at25fs010", INFO(0x1f6601, 0, 32 * 1024, 4, SECT_4K) },
- { "at25fs040", INFO(0x1f6604, 0, 64 * 1024, 8, SECT_4K) },
+ { "at25fs010", INFO(0x1f6601, 0, 32 * 1024, 4, SECT_4K |
SPI_NOR_HAS_LOCK) },
https://datasheetspdf.com/pdf-file/587164/ATMELCorporation/AT25FS010/1
BP bits are at bit 2, 3, 5 and 6.
BP0, BP1, BP3, BP4 and WPEN, are nonvolatile cells
+ { "at25fs040", INFO(0x1f6604, 0, 64 * 1024, 8, SECT_4K |
SPI_NOR_HAS_LOCK) },
https://datasheetspdf.com/pdf-file/587165/ATMELCorporation/AT25FS040/1
BP bits are at bit 2, 3, 4, 5, and 6.
BP0, BP1, BP2, BP3, BP4 are nonvolatile cells
- { "at25df041a", INFO(0x1f4401, 0, 64 * 1024, 8, SECT_4K) },
- { "at25df321", INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K) },
- { "at25df321a", INFO(0x1f4701, 0, 64 * 1024, 64, SECT_4K) },
- { "at25df641", INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },
+ { "at25df041a", INFO(0x1f4401, 0, 64 * 1024, 8, SECT_4K |
SPI_NOR_HAS_LOCK) },
https://datasheetspdf.com/pdf-file/975331/Adesto/AT25DF041A/1
Global Protect/Unprotect using Write SR command:
Global Unlock: write 0x00 to SR
Global Lock: Read SR. If SR.SPRL is 1 write 0xff to SR, else write
0x7f.
That is not my understanding. Quote:
To perform a Global Protect, the appropriate WP pin and SPRL
conditions must be met, and the system must write a logical “1”
to bits 5, 4, 3, and 2 of the Status Register.
And
Conversely, to per-form a Global Unprotect, the same WP and SPRL
conditions must be met but the system must write a logical “0” to
bits 5, 4, 3, and 2 of the Status Register
Keep in mind that bit 5, 4, 3 and 2 is exactly the
ATMEL_SR_GLOBAL_PROTECT_MASK. The SPRL bit is handled in the unlock()
function. Accoring to table 9.2 you also have to first disable the SPRL
bit and then write the BP bits to zero.
-michael
