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| author | Tudor Ambarus <tudor.ambarus@linaro.org> | 2023-11-24 19:49:02 +0100 |
|---|---|---|
| committer | Tudor Ambarus <tudor.ambarus@linaro.org> | 2023-11-24 21:11:19 +0100 |
| commit | 9b3eae3486c86304e047829cfe0073b66dc02b36 (patch) | |
| tree | d3fdc1a031cccd4dc864ea54f00692c2f7c37216 /Documentation/driver-api | |
| parent | docs: mtd: spi-nor: add sections about flash additions and testing (diff) | |
| download | linux-9b3eae3486c86304e047829cfe0073b66dc02b36.tar.xz linux-9b3eae3486c86304e047829cfe0073b66dc02b36.zip | |
docs: mtd: spi-nor: drop obsolete info
The architecture description is obsolete, it no longer applies to
the current SPI NOR framework state, remove it.
Reviewed-by: Michael Walle <michael@walle.cc>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://lore.kernel.org/r/20231124184902.1194235-3-tudor.ambarus@linaro.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/mtd/spi-nor.rst | 62 |
1 files changed, 0 insertions, 62 deletions
diff --git a/Documentation/driver-api/mtd/spi-nor.rst b/Documentation/driver-api/mtd/spi-nor.rst index 628096e578c7..148fa4288760 100644 --- a/Documentation/driver-api/mtd/spi-nor.rst +++ b/Documentation/driver-api/mtd/spi-nor.rst @@ -2,68 +2,6 @@ SPI NOR framework ================= -Part I - Why do we need this framework? ---------------------------------------- - -SPI bus controllers (drivers/spi/) only deal with streams of bytes; the bus -controller operates agnostic of the specific device attached. However, some -controllers (such as Freescale's QuadSPI controller) cannot easily handle -arbitrary streams of bytes, but rather are designed specifically for SPI NOR. - -In particular, Freescale's QuadSPI controller must know the NOR commands to -find the right LUT sequence. Unfortunately, the SPI subsystem has no notion of -opcodes, addresses, or data payloads; a SPI controller simply knows to send or -receive bytes (Tx and Rx). Therefore, we must define a new layering scheme under -which the controller driver is aware of the opcodes, addressing, and other -details of the SPI NOR protocol. - -Part II - How does the framework work? --------------------------------------- - -This framework just adds a new layer between the MTD and the SPI bus driver. -With this new layer, the SPI NOR controller driver does not depend on the -m25p80 code anymore. - -Before this framework, the layer is like:: - - MTD - ------------------------ - m25p80 - ------------------------ - SPI bus driver - ------------------------ - SPI NOR chip - -After this framework, the layer is like:: - - MTD - ------------------------ - SPI NOR framework - ------------------------ - m25p80 - ------------------------ - SPI bus driver - ------------------------ - SPI NOR chip - -With the SPI NOR controller driver (Freescale QuadSPI), it looks like:: - - MTD - ------------------------ - SPI NOR framework - ------------------------ - fsl-quadSPI - ------------------------ - SPI NOR chip - -Part III - How can drivers use the framework? ---------------------------------------------- - -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 ----------------------------------- |