SPI: DUAL/QUAD support

[Gupta, Pekon]

> > [Pekon]: Does below generic framework for spianand, suit your driver?
> > http://lists.infradead.org/pipermail/linux-mtd/2013-July/047434.html
> >
> > you should be able to extend the generic spinand API for all
> > serial modes (SPI, Dual-SPI, Quad-SPI).
> > As QSPI and Dual-SPI devices should implicitly support SPI (MISO/MOSI)
> > So, you can do device probing using default SPI mode. And then based on
> > DT inputs and device support upgrade to QSPI / Dual-SPI mode.
> > And going forward extend it for direct memory-mapped device for XIP.
> 
> Not sure what you have in mind since NAND and NOR flash work very
> differently, and SPI vs. memory-mapped is also very different.
> 
[Pekon]:  Opps.. Sorry for NAND v/s NOR confusion,
But I found generic framework for SPINAND (not in mainline) helpful
for us, so I pointed that..
I'm not sure about your end use-case, but I our QSPI controller supports
direct memory-addressable cpu-side bus-interface which can be enabled
for XIP support. So pointed out that here as-well..


> But to add to the spinand review comments two things caught
> my eye on quick glance over the code:
> 
> > +#define mu_spi_nand_driver_version "Beagle-
> MTD_01.00_Linux2.6.33_20100507"
> 
> seems like an unused leftover?  if the version number is
> important then maybe better put it in commit message?
> 
> > +/bin/bash: 4: command not found
> 
> how did this get in there?
> 
[Pekon]: Thanks.. Sourav needs to clean this up lot more.

with regards, pekon