Re: [PATCH v4 0/7] mtd: spi-nor: add a new framework for SPI NOR

于 2014年01月16日 03:15, Jagan Teki 写道:

Hi,

On Wed, Dec 25, 2013 at 11:20 AM, Huang Shijie[off-list ref]  wrote:

quoted

1.) Why add a new framework for SPI NOR?
   The SPI-NOR controller such as Freescale's Quadspi controller is working
   in a different way from the SPI bus. It should knows the NOR commands to
   find the right LUT sequence. Unfortunately, the current code can not meet
   this requirement.

2.) How does this patch set do?
    This patch set adds a new spi-nor layer.
    Before this patch, the layer is like:

                    MTD
          ------------------------
                   m25p80
          ------------------------
                spi bus driver
          ------------------------
                 SPI NOR chip

    After this patch, the layer is like:
                    MTD
          ------------------------
                   spi-nor
          ------------------------
                   m25p80
          ------------------------
                spi bus driver
          ------------------------
                SPI NOR chip

   With the spi-nor controller driver(Freescale Quadspi), it looks like:
                    MTD
          ------------------------
                   spi-nor
          ------------------------
                 fsl-quadspi
          ------------------------
                SPI NOR chip

I'm new to this thread, may be I'll ask basic questions.
1) what does m25p80 contains with your new framework - will excludes
quad stuff if they add

sorry, i do not understand your meaning.

do you think the m25p80 can not support the quad read after this patch set?

2) I didn't understand why the controller driver fsl-quadspi will be
in mtd becuase as it's (q)spi driver
may does flash or non-flash functionalities if ie, the case should be
part of drivers/spi/*

Please read this thread, Mark though it should be spi nor driver:

http://marc.info/?l=linux-arm-kernel&m=137782885415953&w=2

3) Can you explain your framework precisely take an example of like
spi_controller_A with spi_flash_A
and qspi_controller_B and qspi_flash_B - how will this new framework operates.

The framework is just cloned from the m25p80.c, and extract the common 
code, and provides more
hooks such as

@prepare/unpreare: used to do some work before or after the
              read/write/erase/lock/unlock.
     @read_xfer/write_xfer: We can use these two hooks to code all
              the following hooks if the driver tries to implement them
              by itself.
     @read_reg: used to read the registers, such as read status register,
              read configure register.
     @write_reg: used to write the registers, such as write enable,
              erase sector.
     @read_id: read out the ID info.
     @wait_till_ready: wait till the NOR becomes ready.
     @read: read out the data from the NOR.
     @write: write data to the NOR.
     @erase: erase a sector of the NOR.



The drivers can implement these hooks.

thanks
Huang Shijie






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