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Message-ID: <7194991f6f307a84356e18543f27cf49@walle.cc>
Date: Thu, 23 Nov 2023 17:14:51 +0100
From: Michael Walle <michael@...le.cc>
To: Tudor Ambarus <tudor.ambarus@...aro.org>
Cc: pratyush@...nel.org, linux-mtd@...ts.infradead.org,
linux-doc@...r.kernel.org, corbet@....net,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] docs: mtd: spi-nor: add sections about flash
additions and testing
Hi Tudor,
> Add sections about how to propose a new flash addition and about the
> minimum testing requirements.
Thanks for doing this :)
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
> ---
> Documentation/driver-api/mtd/spi-nor.rst | 189 +++++++++++++++++++++++
> 1 file changed, 189 insertions(+)
>
> diff --git a/Documentation/driver-api/mtd/spi-nor.rst
> b/Documentation/driver-api/mtd/spi-nor.rst
> index c22f8c0f7950..cc8e81e09544 100644
> --- a/Documentation/driver-api/mtd/spi-nor.rst
> +++ b/Documentation/driver-api/mtd/spi-nor.rst
> @@ -63,3 +63,192 @@ The main API is spi_nor_scan(). Before you call the
> hook, a driver should
> initialize the necessary fields for spi_nor{}. Please see
> drivers/mtd/spi-nor/spi-nor.c for detail. Please also refer to
> spi-fsl-qspi.c
> when you want to write a new driver for a SPI NOR controller.
> +
> +How to propose a new flash addition
> +-----------------------------------
> +
> +Most SPI NOR flashes comply with the JEDEC JESD216
> +Serial Flash Discoverable Parameter (SFDP) standard. SFDP describes
> +the functional and feature capabilities of serial flash devices in a
> +standard set of internal read-only parameter tables.
> +
> +The SPI NOR driver queries the SFDP tables in order to determine the
> +flash's parameters and settings. If the flash defines the SFDP tables
> +it's likely that you won't need a flash entry at all, and instead
> +rely on the generic flash driver which probes the flash solely based
> +on its SFDP data. All one has to do is to specify the "jedec,spi-nor"
> +compatible in the device tree.
> +
> +There are cases however where you need to define an explicit flash
> +entry. This typically happens when the flash has settings or support
> +that is not covered by the SFDP tables (e.g. Block Protection), or
> +when the flash contains mangled SFDP data. If the later, one needs
> +to implement the ``spi_nor_fixups`` hooks in order to amend the SFDP
> +parameters with the correct values.
> +
> +Minimum testing requirements
> +-----------------------------
> +
> +Do all the tests from below and paste them in the commit's comments
> +section, after the ``---`` marker.
> +
> +1/ Specify the controller that you used to test the flash and specify
> +the frequency at which the flash was operated::
> +
> + E.g. This flash is populated on the X board and was tested at Y
> + frequency using the Z (put compatible) SPI controller.
> +
> +2/ Dump the sysfs entries and print the md5/sha1/sha256 SFDP
> checksum::
> +
> + root@1:~# cat /sys/bus/spi/devices/spi1.0/spi-nor/partname
> + sst26vf064b
> + root@1:~# cat /sys/bus/spi/devices/spi1.0/spi-nor/jedec_id
> + bf2643
> + root@1:~# cat /sys/bus/spi/devices/spi1.0/spi-nor/manufacturer
> + sst
> + root@1:~# hexdump -C /sys/bus/spi/devices/spi1.0/spi-nor/sfdp
Please use "xxd -p" (and maybe mention that if xxd is not available,
"hexdump -Cv" could be used instead). With xxd one can just use "xxd
-rp"
to generate a binary again.
Otherwise looks good. So with the above fixed:
Reviewed-by: Michael Walle <michael@...le.cc>
> + 00000000 53 46 44 50 06 01 02 ff 00 06 01 10 30 00 00 ff
> |SFDP........0...|
> + 00000010 81 00 01 06 00 01 00 ff bf 00 01 18 00 02 00 01
> |................|
> + 00000020 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> |................|
> + 00000030 fd 20 f1 ff ff ff ff 03 44 eb 08 6b 08 3b 80 bb |.
> ......D..k.;..|
> + 00000040 fe ff ff ff ff ff 00 ff ff ff 44 0b 0c 20 0d d8
> |..........D.. ..|
> + 00000050 0f d8 10 d8 20 91 48 24 80 6f 1d 81 ed 0f 77 38 |....
> .H$.o....w8|
> + 00000060 30 b0 30 b0 f7 ff ff ff 29 c2 5c ff f0 30 c0 80
> |0.0.....).\..0..|
> + 00000070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> |................|
> + *
> + 00000100 ff 00 04 ff f3 7f 00 00 f5 7f 00 00 f9 ff 7d 00
> |..............}.|
> + 00000110 f5 7f 00 00 f3 7f 00 00 ff ff ff ff ff ff ff ff
> |................|
> + 00000120 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> |................|
> + *
> + 00000200 bf 26 43 ff b9 5f fd ff 30 f2 60 f3 32 ff 0a 12
> |.&C.._..0.`.2...|
> + 00000210 23 46 ff 0f 19 32 0f 19 19 ff ff ff ff ff ff ff
> |#F...2..........|
> + 00000220 00 66 99 38 ff 05 01 35 06 04 02 32 b0 30 72 42
> |.f.8...5...2.0rB|
> + 00000230 8d e8 98 88 a5 85 c0 9f af 5a ff ff 06 ec 06 0c
> |.........Z......|
> + 00000240 00 03 08 0b ff ff ff ff ff 07 ff ff 02 02 ff 06
> |................|
> + 00000250 03 00 fd fd 04 07 00 fc 03 00 fe fe 02 02 07 0e
> |................|
> + 00000260
> + root@1:~# sha256sum /sys/bus/spi/devices/spi1.0/spi-nor/sfdp
> + 428f34d0461876f189ac97f93e68a05fa6428c6650b3b7baf736a921e5898ed1
> /sys/bus/spi/devices/spi1.0/spi-nor/sfdp
> +
> +3/ Dump debugfs data::
> +
> + root@1:~# cat /sys/kernel/debug/spi-nor/spi1.0/capabilities
> + Supported read modes by the flash
> + 1S-1S-1S
> + opcode 0x03
> + mode cycles 0
> + dummy cycles 0
> + 1S-1S-1S (fast read)
> + opcode 0x0b
> + mode cycles 0
> + dummy cycles 8
> + 1S-1S-2S
> + opcode 0x3b
> + mode cycles 0
> + dummy cycles 8
> + 1S-2S-2S
> + opcode 0xbb
> + mode cycles 4
> + dummy cycles 0
> + 1S-1S-4S
> + opcode 0x6b
> + mode cycles 0
> + dummy cycles 8
> + 1S-4S-4S
> + opcode 0xeb
> + mode cycles 2
> + dummy cycles 4
> + 4S-4S-4S
> + opcode 0x0b
> + mode cycles 2
> + dummy cycles 4
> +
> + Supported page program modes by the flash
> + 1S-1S-1S
> + opcode 0x02
> +
> + root@1:~# cat /sys/kernel/debug/spi-nor/spi1.0/params
> + name sst26vf064b
> + id bf 26 43 bf 26 43
> + size 8.00 MiB
> + write size 1
> + page size 256
> + address nbytes 3
> + flags HAS_LOCK | HAS_16BIT_SR | SOFT_RESET | SWP_IS_VOLATILE
> +
> + opcodes
> + read 0xeb
> + dummy cycles 6
> + erase 0x20
> + program 0x02
> + 8D extension none
> +
> + protocols
> + read 1S-4S-4S
> + write 1S-1S-1S
> + register 1S-1S-1S
> +
> + erase commands
> + 20 (4.00 KiB) [0]
> + d8 (8.00 KiB) [1]
> + d8 (32.0 KiB) [2]
> + d8 (64.0 KiB) [3]
> + c7 (8.00 MiB)
> +
> + sector map
> + region (in hex) | erase mask | flags
> + ------------------+------------+----------
> + 00000000-00007fff | [01 ] |
> + 00008000-0000ffff | [0 2 ] |
> + 00010000-007effff | [0 3] |
> + 007f0000-007f7fff | [0 2 ] |
> + 007f8000-007fffff | [01 ] |
> +
> +4/ Use `mtd-utils <https://git.infradead.org/mtd-utils.git>`__
> +and verify that erase, read and page program operations work fine.
> +
> +a/ Generate a 2 MB file::
> +
> + root@1:~# dd if=/dev/urandom of=./spi_test bs=1M count=2
> + 2+0 records in
> + 2+0 records out
> + 2097152 bytes (2.1 MB, 2.0 MiB) copied, 0.848566 s, 2.5 MB/s
> +
> +b/ Verify erase::
> +
> + root@1:~# mtd_debug write /dev/mtd1 0 2097152 spi_test
> + Copied 2097152 bytes from spi_test to address 0x00000000 in flash
> +
> + root@1:~# mtd_debug erase /dev/mtd1 0 2097152
> + Erased 2097152 bytes from address 0x00000000 in flash
> +
> + root@1:~# mtd_debug read /dev/mtd1 0 2097152 spi_read
> + Copied 2097152 bytes from address 0x00000000 in flash to spi_read
> +
> + root@1:~# hexdump -C spi_read
> + 00000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> |................|
> + *
> + 00200000
> +
> +c/ Write, read back and compare::
> +
> + root@1:~# mtd_debug write /dev/mtd1 0 2097152 spi_test
> + Copied 2097152 bytes from spi_test to address 0x00000000 in flash
> +
> + root@1:~# mtd_debug read /dev/mtd1 0 2097152 spi_read
> + Copied 2097152 bytes from address 0x00000000 in flash to spi_read
> +
> + root@1:~# sha1sum spi_*
> + 51eeddc316a4121cf96e76e526d94d638283ec22 spi_read
> + 51eeddc316a4121cf96e76e526d94d638283ec22 spi_test
> +
> +d/ Dump mtd_info data::
> +
> + root@1:~# mtd_debug info /dev/mtd1
> + mtd.type = MTD_NORFLASH
> + mtd.flags = MTD_CAP_NORFLASH
> + mtd.size = 8388608 (8M)
> + mtd.erasesize = 4096 (4K)
> + mtd.writesize = 1
> + mtd.oobsize = 0
> + regions = 0
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