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author | Tudor Ambarus <tudor.ambarus@linaro.org> | 2023-11-24 19:49:01 +0100 |
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committer | Tudor Ambarus <tudor.ambarus@linaro.org> | 2023-11-24 21:11:13 +0100 |
commit | bb1f9e39c1bf7349405a48d2c77087dff6cea32b (patch) | |
tree | fc22be219a48019429286ef1aae08d3d4265dd18 | |
parent | MAINTAINERS: spi-nor: add myself as maintainer (diff) | |
download | linux-bb1f9e39c1bf7349405a48d2c77087dff6cea32b.tar.xz linux-bb1f9e39c1bf7349405a48d2c77087dff6cea32b.zip |
docs: mtd: spi-nor: add sections about flash additions and testing
Add sections about how to propose a new flash addition and about the
minimum testing requirements.
Reviewed-by: Michael Walle <michael@walle.cc>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://lore.kernel.org/r/20231124184902.1194235-2-tudor.ambarus@linaro.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
-rw-r--r-- | Documentation/driver-api/mtd/spi-nor.rst | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/Documentation/driver-api/mtd/spi-nor.rst b/Documentation/driver-api/mtd/spi-nor.rst index c22f8c0f7950..628096e578c7 100644 --- a/Documentation/driver-api/mtd/spi-nor.rst +++ b/Documentation/driver-api/mtd/spi-nor.rst @@ -63,3 +63,205 @@ 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/spi0.0/spi-nor/partname + sst26vf064b + root@1:~# cat /sys/bus/spi/devices/spi0.0/spi-nor/jedec_id + bf2643 + root@1:~# cat /sys/bus/spi/devices/spi0.0/spi-nor/manufacturer + sst + root@1:~# xxd -p /sys/bus/spi/devices/spi0.0/spi-nor/sfdp + 53464450060102ff00060110300000ff81000106000100ffbf0001180002 + 0001fffffffffffffffffffffffffffffffffd20f1ffffffff0344eb086b + 083b80bbfeffffffffff00ffffff440b0c200dd80fd810d820914824806f + 1d81ed0f773830b030b0f7ffffff29c25cfff030c080ffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffff0004fff37f0000f57f0000f9ff + 7d00f57f0000f37f0000ffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff + ffffbf2643ffb95ffdff30f260f332ff0a122346ff0f19320f1919ffffff + ffffffff00669938ff05013506040232b03072428de89888a585c09faf5a + ffff06ec060c0003080bffffffffff07ffff0202ff060300fdfd040700fc + 0300fefe0202070e + root@1:~# sha256sum /sys/bus/spi/devices/spi0.0/spi-nor/sfdp + 428f34d0461876f189ac97f93e68a05fa6428c6650b3b7baf736a921e5898ed1 /sys/bus/spi/devices/spi0.0/spi-nor/sfdp + + Please dump the SFDP tables using ``xxd -p``. It enables us to do + the reverse operation and convert the hexdump to binary with + ``xxd -rp``. Dumping the SFDP data with ``hexdump -Cv`` is accepted, + but less desirable. + +3) Dump debugfs data:: + + root@1:~# cat /sys/kernel/debug/spi-nor/spi0.0/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/spi0.0/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:: + + 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 + + root@1:~# mtd_debug erase /dev/mtd0 0 2097152 + Erased 2097152 bytes from address 0x00000000 in flash + + root@1:~# mtd_debug read /dev/mtd0 0 2097152 spi_read + Copied 2097152 bytes from address 0x00000000 in flash to spi_read + + root@1:~# hexdump spi_read + 0000000 ffff ffff ffff ffff ffff ffff ffff ffff + * + 0200000 + + root@1:~# sha256sum spi_read + 4bda3a28f4ffe603c0ec1258c0034d65a1a0d35ab7bd523a834608adabf03cc5 spi_read + + root@1:~# mtd_debug write /dev/mtd0 0 2097152 spi_test + Copied 2097152 bytes from spi_test to address 0x00000000 in flash + + root@1:~# mtd_debug read /dev/mtd0 0 2097152 spi_read + Copied 2097152 bytes from address 0x00000000 in flash to spi_read + + root@1:~# sha256sum spi* + c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8 spi_read + c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8 spi_test + + If the flash comes erased by default and the previous erase was ignored, + we won't catch it, thus test the erase again:: + + root@1:~# mtd_debug erase /dev/mtd0 0 2097152 + Erased 2097152 bytes from address 0x00000000 in flash + + root@1:~# mtd_debug read /dev/mtd0 0 2097152 spi_read + Copied 2097152 bytes from address 0x00000000 in flash to spi_read + + root@1:~# sha256sum spi* + 4bda3a28f4ffe603c0ec1258c0034d65a1a0d35ab7bd523a834608adabf03cc5 spi_read + c444216a6ba2a4a66cccd60a0dd062bce4b865dd52b200ef5e21838c4b899ac8 spi_test + + Dump some other relevant data:: + + root@1:~# mtd_debug info /dev/mtd0 + 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 |