Re: [PATCH v5 1/3] mtd: spi-nor: atmel: remove global protection flag

From: Tudor.Ambarus
Date: Tue Nov 24 2020 - 14:09:35 EST

On 10/3/20 6:32 PM, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> This is considered bad for the following reasons:
> (1) We only support the block protection with BPn bits for write
> protection. Not all Atmel parts support this.
> (2) Newly added flash chip will automatically inherit the "has
> locking" support and thus needs to explicitly tested. Better
> be opt-in instead of opt-out.
> (3) There are already supported flashes which doesn't support
> the locking scheme. So I assume this wasn't properly tested
> before adding that chip; which enforces my previous argument
> that locking support should be an opt-in.
>
> Remove the global flag and add individual flags to all flashes which
> supports BP locking. In particular the following flashes don't support
> the BP scheme:
> - AT26F004
> - AT25SL321
> - AT45DB081D
>
> Please note, that some flashes which are marked as SPI_NOR_HAS_LOCK just
> support Global Protection, i.e. not our supported block protection
> locking scheme. This is to keep backwards compatibility with the
> current "unlock all at boot" mechanism. In particular the following
> flashes doesn't have BP bits:
> - AT25DF041A
> - AT25DF321
> - AT25DF321A
> - AT25DF641
> - AT26DF081A
> - AT26DF161A
> - AT26DF321
>
> Signed-off-by: Michael Walle <michael@xxxxxxxx>

Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>

> ---
> 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.

Upon device power-up or after a device reset, each Sector Protection
Register will default to the logical “1” state indicating that all
sectors are protected and cannot be programmed or erased.


> + { "at25df321", INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K | SPI_NOR_HAS_LOCK) },

https://datasheetspdf.com/pdf-file/609207/ATMELCorporation/AT25DF321/1
Global Protect/Unprotect same as in at25df041a.

> + { "at25df321a", INFO(0x1f4701, 0, 64 * 1024, 64, SECT_4K | SPI_NOR_HAS_LOCK) },

https://datasheetspdf.com/pdf-file/829669/Adesto/AT25DF321A/1
Global Protect/Unprotect same as in at25df041a.

> + { "at25df641", INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K | SPI_NOR_HAS_LOCK) },

https://www.adestotech.com/wp-content/uploads/doc3680.pdf
Global Protect/Unprotect same as in at25df041a.

>
> { "at25sl321", INFO(0x1f4216, 0, 64 * 1024, 64,
> SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },

https://www.adestotech.com/wp-content/uploads/AT25SL321_112.pdf
Ok, just hw write protection.

>
> { "at26f004", INFO(0x1f0400, 0, 64 * 1024, 8, SECT_4K) },

https://cdn.sos.sk/productdata/08/5e/c7c8063e/at-26-f004-ssu.pdf
OK, never worked, just Individual Sector Protection for Program/Erase Protection

> - { "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K) },
> - { "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K) },
> - { "at26df321", INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K) },
> + { "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K | SPI_NOR_HAS_LOCK) },

https://www.adestotech.com/wp-content/uploads/doc3600.pdf
Global Protect/Unprotect same as in at25df041a.

> + { "at26df161a", INFO(0x1f4601, 0, 64 * 1024, 32, SECT_4K | SPI_NOR_HAS_LOCK) },

https://datasheetspdf.com/pdf-file/562306/ATMELCorporation/AT26DF161/1
Global Protect/Unprotect same as in at25df041a.

> + { "at26df321", INFO(0x1f4700, 0, 64 * 1024, 64, SECT_4K | SPI_NOR_HAS_LOCK) },

https://datasheetspdf.com/pdf-file/609208/ATMELCorporation/AT26DF321/1
Global Protect/Unprotect same as in at25df041a.

>
> { "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },

https://datasheetspdf.com/pdf-file/856198/Adesto/AT45DB081D/1
OK. Individual sector protection.

> };
>
> -static void atmel_default_init(struct spi_nor *nor)
> -{
> - nor->flags |= SNOR_F_HAS_LOCK;
> -}
> -
> -static const struct spi_nor_fixups atmel_fixups = {
> - .default_init = atmel_default_init,
> -};
> -
> const struct spi_nor_manufacturer spi_nor_atmel = {
> .name = "atmel",
> .parts = atmel_parts,
> .nparts = ARRAY_SIZE(atmel_parts),
> - .fixups = &atmel_fixups,
> };
> --
> 2.20.1
>