Add sections about how to propose a new flash addition and about the minimum testing requirements. Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx> --- 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 + 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 -- 2.34.1