Re: [PATCH v5 2/3] mtd: spi-nor: sst: remove global protection flag

From: Tudor.Ambarus
Date: Tue Nov 24 2020 - 14:50:42 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 SST 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:
> - SST26VF016B
> - SST26WF016B
> - SST26VF064B
>
> 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:
> - none
>
> drivers/mtd/spi-nor/sst.c | 30 ++++++++++++------------------
> 1 file changed, 12 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/sst.c b/drivers/mtd/spi-nor/sst.c
> index e0af6d25d573..8b169fa4102a 100644
> --- a/drivers/mtd/spi-nor/sst.c
> +++ b/drivers/mtd/spi-nor/sst.c
> @@ -11,26 +11,26 @@
> static const struct flash_info sst_parts[] = {
> /* SST -- large erase sizes are "overlays", "sectors" are 4K */
> { "sst25vf040b", INFO(0xbf258d, 0, 64 * 1024, 8,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/DS20005051D.pdf
BP GENMASK(2, 5), volatile, after power up BP0-2 set to 1, BP3 set to 0.
BP3 is "don't care".
SR.BPL BIT(7) volatile, default to 0. When 1 - BPs are read-only bits,
when 0 - BPs are r/w

> { "sst25vf080b", INFO(0xbf258e, 0, 64 * 1024, 16,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/20005045C.pdf
same as in sst25vf040b

> { "sst25vf016b", INFO(0xbf2541, 0, 64 * 1024, 32,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/20005044C.pdf
same as in sst25vf040b


> { "sst25vf032b", INFO(0xbf254a, 0, 64 * 1024, 64,
> - SECT_4K | SST_WRITE) },
> - { "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/20005071B.pdf
same as in sst25vf040b

> + { "sst25vf064c", INFO(0xbf254b, 0, 64 * 1024, 128, SECT_4K | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/devicedoc/20005036c.pdf
BP GENMASK(2, 5), volatile, after power up all set to 1.
SR.BPL BIT(7) volatile, default to 0. When 1 - BPs are read-only bits,
when 0 - BPs are r/w

> { "sst25wf512", INFO(0xbf2501, 0, 64 * 1024, 1,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/20005016C.pdf
BP GENMASK(2, 4), volatile, after power up all set to 1.
SR.BPL BIT(7) volatile, default to 0. When 1 - BPs are read-only bits,
when 0 - BPs are r/w

> { "sst25wf010", INFO(0xbf2502, 0, 64 * 1024, 2,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

same datasheet and characteristics as in sst25wf512

> { "sst25wf020", INFO(0xbf2503, 0, 64 * 1024, 4,
> - SECT_4K | SST_WRITE) },
> - { "sst25wf020a", INFO(0x621612, 0, 64 * 1024, 4, SECT_4K) },
> - { "sst25wf040b", INFO(0x621613, 0, 64 * 1024, 8, SECT_4K) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

same datasheet and characteristics as in sst25wf512

> + { "sst25wf020a", INFO(0x621612, 0, 64 * 1024, 4, SECT_4K | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/20005139F.pdf
BP0 BIT(2), BP1 BIT(3), TB BIT(5), BPL BIT(7) all non-volatile
SR.BPL BIT(7): when 1 - BPs are read-only bits, when 0 - BPs are r/w

> + { "sst25wf040b", INFO(0x621613, 0, 64 * 1024, 8, SECT_4K | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/20005193D.pdf
BP0 BIT(2), BP1 BIT(3), BP2 BIT(4), TB BIT(5), BPL BIT(7) all non-volatile
SR.BPL BIT(7): when 1 - BPs are read-only bits, when 0 - BPs are r/w

> { "sst25wf040", INFO(0xbf2504, 0, 64 * 1024, 8,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

same datasheet and characteristics as in sst25wf512

> { "sst25wf080", INFO(0xbf2505, 0, 64 * 1024, 16,
> - SECT_4K | SST_WRITE) },
> + SECT_4K | SST_WRITE | SPI_NOR_HAS_LOCK) },

https://ww1.microchip.com/downloads/en/DeviceDoc/25024A.pdf
same as in sst25vf040b

> { "sst26wf016b", INFO(0xbf2651, 0, 64 * 1024, 32,

https://ww1.microchip.com/downloads/en/DeviceDoc/20005013D.pdf
OK. sst26wf016b, SST26VF016B, SST26VF064B support individual block protection
and global unlock command.

> SECT_4K | SPI_NOR_DUAL_READ |
> SPI_NOR_QUAD_READ) },
> @@ -127,11 +127,6 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
> return ret;
> }
>
> -static void sst_default_init(struct spi_nor *nor)
> -{
> - nor->flags |= SNOR_F_HAS_LOCK;
> -}
> -
> static void sst_post_sfdp_fixups(struct spi_nor *nor)
> {
> if (nor->info->flags & SST_WRITE)
> @@ -139,7 +134,6 @@ static void sst_post_sfdp_fixups(struct spi_nor *nor)
> }
>
> static const struct spi_nor_fixups sst_fixups = {
> - .default_init = sst_default_init,
> .post_sfdp = sst_post_sfdp_fixups,
> };
>
> --
> 2.20.1
>