Qspi flash device driver - framework to use?

Qspi flash device driver - framework to use?

[Sourav Poddar]

Hi,

I am trying to work out a way to write a QSPI serial flash interface driver
for my IP. The idea is to have an execute in place usecase.

We have a configuration port from which the spi core can be configured and a
memory mapped port from which the data can be read/write from/to serial
flash device.

As far as I can understand, I dont think it will be correct/possible to 
write this
driver making use of the generice spi framework(drivers/spi/spi.c) as that
framework is more suited for generic spi use case, where in you can load
your Image from external SPI devices into DDR and then execute. ?

But for cases, where qspi is connected to serial flash device (XIP is 
needed) what
we might need is some framework which just passes the buffers and its 
length to
our driver which in turn will configure the qspi to initiate the transfer.

What can be the best framework to use for the above use case?

I saw a device(m25p80) using mtd framework for some similar usecase.
Is it the mtd which should be used? OR will it be a
good idea to go for a generic qspi framework(drivers/qspi) which can be
used by qspi flash devices having a memory mapped interface. ?

Thanks,
Sourav

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Re: Qspi flash device driver - framework to use?

[Santosh Shilimkar]

On Friday 10 May 2013 04:47 PM, Mark Brown wrote:
> On Fri, May 10, 2013 at 04:39:50PM +0530, Sourav Poddar wrote:
> 
>> I saw a device(m25p80) using mtd framework for some similar usecase.
>> Is it the mtd which should be used? OR will it be a
>> good idea to go for a generic qspi framework(drivers/qspi) which can be
>> used by qspi flash devices having a memory mapped interface. ?
> 
> MTD does seem like a much better fit here - if you're memory mapping
> things the whole goal is to make the fact that there's SPI involved
> totally transparent to the processor so there shouldn't really be
> anything for the SPI subsystem to do.
> 
+1 for MTD

Regards,
Santosh

------------------------------------------------------------------------------
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"Graph Databases" is the definitive new guide to graph databases and 
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leaders in the field. The early access version is available now. 
Download your free book today! http://p.sf.net/sfu/neotech_d2d_may

Re: Qspi flash device driver - framework to use?

[Sourav Poddar]

+ linux-mtd list
On Friday 10 May 2013 04:39 PM, Sourav Poddar wrote:
> Hi,
>
> I am trying to work out a way to write a QSPI serial flash interface 
> driver
> for my IP. The idea is to have an execute in place usecase.
>
> We have a configuration port from which the spi core can be configured 
> and a
> memory mapped port from which the data can be read/write from/to serial
> flash device.
>
> As far as I can understand, I dont think it will be correct/possible 
> to write this
> driver making use of the generice spi framework(drivers/spi/spi.c) as 
> that
> framework is more suited for generic spi use case, where in you can load
> your Image from external SPI devices into DDR and then execute. ?
>
> But for cases, where qspi is connected to serial flash device (XIP is 
> needed) what
> we might need is some framework which just passes the buffers and its 
> length to
> our driver which in turn will configure the qspi to initiate the 
> transfer.
>
> What can be the best framework to use for the above use case?
>
> I saw a device(m25p80) using mtd framework for some similar usecase.
> Is it the mtd which should be used? OR will it be a
> good idea to go for a generic qspi framework(drivers/qspi) which can be
> used by qspi flash devices having a memory mapped interface. ?
>
> Thanks,
> Sourav


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