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

On Fri, Jan 17, 2014 at 7:32 AM, Huang Shijie [off-list ref] wrote:

On Thu, Jan 16, 2014 at 03:09:13PM +0530, Jagan Teki wrote:

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

Just for looking on your new framework, is that above link correct.
I guess it should be MTD -- m25p80 -- spi-nor -- spi bus driver -- SPI NOR chip

I do not think so.
The spi-nor layer does not contact with the spi bus driver directly.

Yes - now I understand the flow from seeing the code.
With your new framework
1. not an exact spi-nor
    have one controller driver at drivers/spi/* will register to spi core.
    have m25p80.c will scan the flash details from
drivers/mtd/spi-nor/spi-nor.c and
    m25p80 will register the MTD core and for transfer calls m25p80
will calls spi core.
2. spi-nor style
    have  one controller driver at drivers/mtd/spi-nor/fsl-quadspi.c
will register MTD core
    and scan the flash details from drivers/mtd/spi-nor/spi-nor.c and
for transfer will calls
    through direct writel and readl with cmd+data fashion.

Correct me If my understanding was wrong.

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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.

My basic question is like I have a qspi spi controller in my SOC and I
designed two boards B1 and B2

okay.

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B1 with quad spi controller connected with non-flash as a slave and B2
with quad spi controller connected
with quad flash as a slave.

You can use the framework for B2. But for B1, you should not use the framework,
since this framework is just for the SPI-NOR. If you do not connected with
a NOR, i think it's better to code another driver for your controller.

Means we have two separate controller drivers for same controller one
with spi-nor and
another with spi is it?

Do you think this is a good idea, I understand you have a complete and
well guided new
spi-nor framework.

-- 
Thanks,
Jagan.